We just finished our Black project car and we managed to get 326 at the wheels on a Dyno Dynamics.And 240 ft/lbs of torque to boot.Seehow flat the torque curve is :ylsuper: Here is the dyno chart.http://www.speedforceracing.com/images/products/mazda/rx8/tubokit/rx8_1_6.jpg

WOW, IT SEEMS TO BE ...... PRetty IMPRESSIVE !

but , may I ask what kind of equipment u guys have ?

looking good.

Nice. Also isn't the dyno dynamics usually register even lower hp then even Mustang dynoes.

Just visited your homepage 7500 for the kit :Eyecrazy:

The car is equipped with the SFR turbo system(non ball-bearing).SFR testpipe and a Borla 3" cat-back. Thats it. Nothing else. Running at 9 psi of boost.

Torque Monster for sure

but as I can see in the picture, gotta relocate some of the stuff (battery, for example)

Hmm .... pretty costly, but ahh if it adds like more than 100 hp/tq .... I guess .. hmmm

but as I can see in the picture, gotta relocate some of the stuff (battery, for example)

Hmm .... pretty costly, but ahh if it adds like more than 100 hp/tq .... I guess .. hmmm

The battery relocation kit comes with the system.We make a super nice aluminum battery box that mounts in the trunk and then we supply you with new ground and power cables.The test car dynoed at 175hp and 125 ft/lbs at the wheels so we added 151 horsepower and 115 ft/lbs of torque at the wheels.We also have an even bigger intercooler and turbo option that we havent tested as of yet :Eyecrazy:

Nice numbers man. I bet it's a quick SOB :).

headsnapper for sure...nice...just for kicks...why a non-ball bearing..i'm guessing a T04b?..those like lower oil pressures and less oiling...that the main reason?...or just it's overall scalability? I mean don't get me wrong..i think it's great i'm just wondering your reasons behind putting one in...

$7500 seems like a lot to put out all at once, and no way I could have saved up enough to drop that kind of dough, but really I think its fairly reasonable. Assuming they're using a standalone EMS. If they're still using the emanage, then it is a bit expensive.

Over time I've spent over that on mods for my 8 and still don't have that kinda hp. If you look at turbo kits for other cars its really an average price for a good kit. The price of the Greddy turbo has just spoiled us. But I don't think the Greddy kit is as good quality as this kit, and definitely won't make this kinda power. Its my experience that if you want that kind of power, you're going to have to spend that kind of money (except maybe if you go the NOS route). Unless you own a Mustang and can get 20hp from a set of headers. But it all depends on what you want.

My only complaint is that its not a ball bearing turbo.

SFR could we get some more details about the turbo your using? What kind is it and what's the trim? Also, what kind of engine management are you using?

doesn't the car rev to 9k+ rpm? You seem to be missing ~1150 RPM

Detonation or just lifted early?

EDIT: Just realized this was a :repost: with a picture and that the question was answered already.

SFR could we get some more details about the turbo your using? What kind is it and what's the trim? Also, what kind of engine management are you using?



It is a Turbonetics turbo. TO4E with a 57 trim. The hotside specs is our little secret :yesnod: The engine management is from Injection Perfection and it is basically a TSI unit.The same thing Ric Shaw uses.It controls timing,fuel,boost,it can control NOS,etc....It controls the injectors and ignition timing directly without using the Mass-air sensor to do your fueling corrections.It has a 22 psi MAP sensor in it for accurate pressure measurements.Very nice system and it is as close to stand alone as you can get without having to build a harness,rewire the car,etc.......

Because it does so much , it costs alot which is why the price ofthe turbo kit is up there.But hey if you want to run your own EMS system and figure out your fueling requirements, then you can save alot of money and buy a tuner kit.
:shocking:

What is the price for the tuner kit?

It's on the website

Dang nice gains. Do you planning to take that 8 to a track...it wold be cool for the customer to not only see a dyno but the real world application on a track. Just...so we could hear and see what those numbers could do.

By the way, anyone know what type of whp Adrian-1 is hitting? He just got a 13.1 in the 1/4 mile and we could use his greddy turbo to estimate/guestimate what the SFR Turbo could do.

we could use his greddy turbo to estimate/guestimate what the SFR Turbo could do.
There are so many different variables involved... i would think its just better to wait till an SFR turbo kit owner shows 1/4 mile times.

OR... just for kicks, you could use this
http://www.rx7.com/accel_calculator.html

-hS

Cool...that looks pretty fun, now is that whp or flywheel?

...and what do they mean shifts vs gear?

Like...how many shifts to 60mph and what gear....I don't understand that part??

Yeah, why not rev it all the way up?

There are so many different variables involved... i would think its just better to wait till an SFR turbo kit owner shows 1/4 mile times.

OR... just for kicks, you could use this
http://www.rx7.com/accel_calculator.html

-hS
Just to piggy back on this, with such a big difference in power, I'm sure the car would be at least from 0.4-0.7 sec faster, but traction would be the biggest problem. Traction for a tuned GReddy turbo'd car is bad enough, I can't imagine what it would be like with this sucker.

Ya, but there's things that can be done to help with that. Stickier tires would be the biggest. Vivid also makes some traction bars, but I don't know how well they work.

Yes, I am a novice in rotary engine technology...
I don't understand why the HP/Torque peaks at 7200 and then peters out...
So really, from 7200 to 9500 is pretty much useless.... is this correct?
They've turned our rotary into "acting like" a piston engine,
except there's no appreciable grunt off the line...

I don't get it (stupid is as stupid does)?!

"peters out"???

WTF. Its still putting down 320HP when the dyno chart ends. I wish I "petered out" above 300whp.

haha, Dont we all!

Whao, and this is actually for sale. Interesting.

Yes, I am a novice in rotary engine technology...
I don't understand why the HP/Torque peaks at 7200 and then peters out...
So really, from 7200 to 9500 is pretty much useless.... is this correct?
They've turned our rotary into "acting like" a piston engine,
except there's no appreciable grunt off the line...

I don't get it (stupid is as stupid does)?!

I imagine its gotta be difficult to size a turbo to work at maximum efficiency throughout such a wide rev range. On any engine, if you want it to spool fast and give lots of low end torque, you usually have to sacrafice some up top. If you want lots up top, then you have to sacrifice spool time and low end torque. With modern turbo's this effect can be greatly mitigated, but it will be somewhat magnified in a rotary since it has such a large cfm range.

So if you want it to hold power till 9krpms stick a bigger turbo on there, but realize your not going to spool up to full boost until 4,5,6... k rpms.

I think I soiled myself

If you got this kit with the Inter-X you still would save $500...so why are we getting your EMS again?

No offense, thank you for working on this and making a product for the RX8!!!!

Also...did I miss it or did you explain why you messured this at 7.2K? I would think you could make more power at a higher RPM or is there a huge drop off or something?

Please explain...us newbs need to know.

If you got this kit with the Inter-X you still would save $500...so why are we getting your EMS again?


For starters.......you could have already had this kit a year ago if you bought a tuner kit.The big problem is everybody and there brother said this kit doesnt make power,we are lying about our claims,we dont know what we are doing,we are idiots,Greddy is the best,etc...........So now we make the power and all of a sudden,hey you can buy this kit and use interceptor X.Why didnt anybody do it sooner? Actually there were quite a few guys that did because they realized the potential of this system right away.Unfortunately, the majority of the masses thought it was impossible to do what we did and provide a real dyno chart.One of our customers seen similiar results with an Emanage but his Emanage is not working right so he is not gettng the smooth idle and drivability that we have.

If you do the math you wont be saving $500 because you still need to get injectors with the interceptor X because we dont provide injectors with the tuner kit.Then add in a boost control solenoid and I dont think you will save anything.On top of that the EMS we supply you is tuned for this application.Sure you might need a little fine tuning for your particular mods but you dont have to tune from scratch so you will save money on dyno time too.



No offense, thank you for working on this and making a product for the RX8!!!!

Also...did I miss it or did you explain why you messured this at 7.2K? I would think you could make more power at a higher RPM or is there a huge drop off or something?



Well you can see that the power starts to drop off at 7850.If I remember correctly at 8500 rpm it is below 290WHP so there is really no use revving it any higher because you are out of the powerband.It is not uncommon for most cars to make peak power before redline and this car is no different.I think some of it has to do with the butterfly system and the fact that this rotary is not as efficient at 9000 rpms.To summarize........if we are making really good power without revving the crap out of the motor, then it means there will be more reliability to the end user.The stress on the motor at 9000 and 10,000 rpms is much greater then at 8000 rpms. :angel: :angel:

if we are making really good power without revving the crap out of the motor, then it means there will be more reliability to the end user.The stress on the motor at 9000 and 10,000 rpms is much greater then at 8000 rpms.

and less stress on the tranny :)

If you do the math you wont be saving $500 because you still need to get injectors with the interceptor X because we dont provide injectors with the tuner kit.

I see...my mistake, thanks.

SFR...OK, I understand now...thanks. (about the 7.2K thing).

Thanks for the hard work...at 9psi that's pretty dang impressive.

Nice results.

What is the larger turbo you guys are going with? I'm assuming that would be to continue climbing with power towards redline?

Does you EMS function like the Interceptor? Or does it manipulate the code like the Emanage? If it functions like the Interceptor, I'm curious how it doesn't trip the "too rich" CEL.

Cool...that looks pretty fun, now is that whp or flywheel?

...and what do they mean shifts vs gear?

Like...how many shifts to 60mph and what gear....I don't understand that part??
I'm pretty sure that is Wheel Horse Power.

Shifts (i believe) is referring to the number of shits in your 1/4 mile - essentially this reflects gear ratios. I am pretty sure on our car it should be around 4 shifts

Gear is referring to weather or not its a 5 or 6 or 7 speed transmission.

If you want a definete answer, you can just call Rotary Performance and ask them for yourself. Their phone number should be up on the website.
-hS

I imagine its gotta be difficult to size a turbo to work at maximum efficiency throughout such a wide rev range. On any engine, if you want it to spool fast and give lots of low end torque, you usually have to sacrafice some up top. If you want lots up top, then you have to sacrifice spool time and low end torque. With modern turbo's this effect can be greatly mitigated, but it will be somewhat magnified in a rotary since it has such a large cfm range.

So if you want it to hold power till 9krpms stick a bigger turbo on there, but realize your not going to spool up to full boost until 4,5,6... k rpms.


Unless you do like Porsche in the new 911 Turbo and use variable turbine geometry system to improve flexibility... http://www.roadandtrack.com/article.asp?section_id=9&article_id=3253

Thanks rkostolni for your helpful explaination, now I don't feel like such a
"rotary retard" :Eyecrazy:
Al

Yes, I am a novice in rotary engine technology...
I don't understand why the HP/Torque peaks at 7200 and then peters out...
So really, from 7200 to 9500 is pretty much useless.... is this correct?
They've turned our rotary into "acting like" a piston engine,
except there's no appreciable grunt off the line...

I don't get it (stupid is as stupid does)?!


I imagine its gotta be difficult to size a turbo to work at maximum efficiency throughout such a wide rev range. On any engine, if you want it to spool fast and give lots of low end torque, you usually have to sacrafice some up top. If you want lots up top, then you have to sacrifice spool time and low end torque. With modern turbo's this effect can be greatly mitigated, but it will be somewhat magnified in a rotary since it has such a large cfm range.

So if you want it to hold power till 9krpms stick a bigger turbo on there, but realize your not going to spool up to full boost until 4,5,6... k rpms.

very interesting. good job SFR.

dd sends...

I'm pretty sure that is Wheel Horse Power.

Shifts (i believe) is referring to the number of shits in your 1/4 mile - essentially this reflects gear ratios. I am pretty sure on our car it should be around 4 shifts

Gear is referring to weather or not its a 5 or 6 or 7 speed transmission.

If you want a definete answer, you can just call Rotary Performance and ask them for yourself. Their phone number should be up on the website.

Thanks! I re-did it and that calculator looks pretty dang accurate.

It "looks like" your setup on an 8 would get us into the mid 12's which is just amazing. I know I know, there are alot of factors (driver, grip, reaction time, weather , modded 8 weight, etc etc) but my goal of 300whp for the RX8 would honestly be more than enough for me.

Gearing - I don't think they are talking about how many your vehicle has - a 4 spd can have the same gear ratios as a 5spd or 6 spd...they are more likely referring to your final drive gear ratio...the RX-8 is 4.44.

Unfortunately, there's a lot of history with SFR and the forum. Most of it is water under the bridge now. But, you're right. There are a lot of doubters here.

Low 13's is pretty easily attainable nowadays. While I haven't gotten a time slip yet, I'd be willing to bet I'm almost there. STi's are supposed to run mid to low 13's and I'm beating them - even though they are really tough to beat off the line with that AWD.

AMEN Charles, I agree 100%!

It's so cool how people doubted the RX8 and now it's making huge power gains and it's also lovely to see the aftermarket for the RX8 blossom into what we have today. No...not perfect and honestly still pricy for me but once my 8 is paid off I'm glad there will be several options to make the 8 faster and better overall.

I think there has been a turning point on this fourm. Ever since the interceptor has produced power gains it seemed to open the flood gates in the minds of the people on this forum. Power is possible and we now know that 300+ whp is much more attainable then we believed 6 months ago. Now the next obsicle is to make the general tuner population to realize what we are slowly realizing, meaning that the 8 is a fast car. I like the idea that we wont have to stay in the twisties to win anything. We now can have some grunt and as of this moment this is the most powerful kit we can buy.

How big is the piping on this kit?

No...not perfect and honestly still pricy for me but once my 8 is paid off I'm glad there will be several options to make the 8 faster and better overall.
That won't be for a while for some of us. (Dang trade-in roll over)!!!

Congrats SFR. Now go to the track and scare people.

Congrats SFR. Now go to the track and scare people.I second that!!!:rock:

To further hijack...Charles, how much does the OEM PPF weigh?

Charles...keep up the good work.

....and NOW...back...to yada yada yada

Charles, do you have access to finite element analysis software, or would that even help? We have AlGor at work, and things are fairly slow for the moment.

Thanks Charles for your support.I feel your pain since we have been through it on these boards just like you.The piping for the RX-8 turbo system is 3" intake. 2" turbo to intercooler and 2.5" to 3" intercooler to throttlebody.

Lemme guess, the "Machinery's Handbook"? ;)

Yeah, it's probably the additional cost of aluminum, the additional cost of welding (or is there any welding, I don't know), etc. Mazda designs cars with a price point in mind just like everyone else, and if you've gotta carry more weight to save money, the bottom center of the car is probably the best place to do it.

If you have an autocad model of your 3 proposed designs, I could analyze them and you could see the weak spots like this, then change materials or design until you reduce the stress to an acceptable level.

http://img58.imageshack.us/img58/349/socketl6ow.gif (http://imageshack.us)

We use algor for huge ball valves, but we've also done steel brackets. The president of the company has waterfront property and needed some special kind of brackets for his bulkhead. :P

Of course, if your designs need to remain classified, that's cool too. :)

Tim, do you have and pictures of the battery relocation box you spoke about?

Tim, do you have and pictures of the battery relocation box you spoke about?



I will take some and post them as soon as I can.




Tim

that is one hell of a peaky powercurve - I'm willin to bet with a ball bearing / smaller turbo you could get a MUCH nicer powercurve at the sacrifice of some peak power.

my GReddy torque curve is absolutely flat from start to finish - that's the way I like my cars to behave.

I am very interested in getting this kit asap. i just still have a few questions. One thing i was wandering is why this kit and the ssr-engineering kit look so much a like. of all the components the only difference i see is the ssr states it comes with a emanage and it states it comes with a fuel pump but the turbo, bov, wg, fmic, piping, air filter, and all the acc. and hardware are exactly the same

and also turbokits.com sells a turbo kit for the RX-8 listed as the "SSR" kit but the picture they are using is the exact same as the picture on your site

SSR/SFR is basically the same kit.

then why is there a $1000 difference

and is the sfr having the tsi ems rather than the greddy emanage worth the extra 1k

then why is there a $1000 difference

and is the sfr having the tsi ems rather than the greddy emanage worth the extra 1k



If you want it pretuned and ready to go right of the box then it might be worth the extra money.

I am very interested in getting this kit asap. i just still have a few questions. One thing i was wandering is why this kit and the ssr-engineering kit look so much a like. of all the components the only difference i see is the ssr states it comes with a emanage and it states it comes with a fuel pump but the turbo, bov, wg, fmic, piping, air filter, and all the acc. and hardware are exactly the same

and also turbokits.com sells a turbo kit for the RX-8 listed as the "SSR" kit but the picture they are using is the exact same as the picture on your site




SSR resells these kits.However they have not spent the time or money that we have on dyno tuning the TSI ECU.So...........if you buy it with an Emanage, you will be spending a good amount of time and money to get it tuned correctly and we cannot guarantee the same results that we have seen with the TSI ECU.

Id be more towerds buying it and using an interceptor, I mean, Hybrid got 310 whp using the greddy turbo, I imagine you could probably achieve a good amount higher with this bigger turbo.

Id be more towerds buying it and using an interceptor, I mean, Hybrid got 310 whp using the greddy turbo, I imagine you could probably achieve a good amount higher with this bigger turbo.



The TSI is very similiar to the interceptor.It controls the ignition and injectors directly without tricking the ECU.Our tune is as good as it is gonna get while being safe and conservative.We only ran 9psi too.The Greddy car is running 13 psi which will probably not last too long even if the tune is perfect.13psi is alot of boost on a high compression rotary.Now if we run 13 psi,look out 400WHP.But again,the motor wont last long at those boost levels.



Tim

Does your ecu have the ability to hold more than one map and be able to switch between them? If so, why not have an insanely high power (like 13psi) and a normal everyday tune to keep the motor in one piece?

If it uses a map sensor like the interceptor does, you don't need to hold different maps for different boost levels. You can change the boost without altering the map, as long as you don't exceed the limits of your tuning.

Also, that is not an accurate statement saying the Renesis will not last as long at 13psi as at 9psi. The Greddy mass flow at 13psi is less than your turbo at 9psi. Inidicated by the power levels. In this particular instance, what matters is cylinder pressure. That is determined by the torque. I suspect that your turbo is outputing more torque, and hence really the motor will last less time with yours.

If it uses a map sensor like the interceptor does, you don't need to hold different maps for different boost levels. You can change the boost without altering the map, as long as you don't exceed the limits of your tuning.

Also, that is not an accurate statement saying the Renesis will not last as long at 13psi as at 9psi. The Greddy mass flow at 13psi is less than your turbo at 9psi. Inidicated by the power levels. In this particular instance, what matters is cylinder pressure. That is determined by the torque. I suspect that your turbo is outputing more torque, and hence really the motor will last less time with yours.



Actually, it is a correct statement.There is one factor that you did not take into consideration....... temperature! At the same boost level, the charge air of the big T4 turbo we are using is going to be alot less then that of a smaller T3 turbo.Somewhere along the lines of 100F! Now add to that the extra 4 psi of boost that the Greddy turbo needs to make 16 less horsepower then we did and the charge air temp is skyrocketing.Somewhere in the enighborhood of 150F higher then the charge air temp from our turbo. So your motor will not last as long at these boost levels as it would at lower boost levels becasause the charge air temp is much greater.




Tim

High charge temperatures are more likely to cause detonation, but they do not contribute significantly to Mean cylinder pressure. MEP is found from MEP=F/A, and Force=torque/D. Clearly cylinder pressure is a function directly related to torque. Any good automotive book will tell you engine wear is related to thermal stress, cylinder pressure, and intertial loads. Cylinder pressure being the operative term here.

Thermal stress can be raised due to high intake temps, but not significantly, especially if you're running proper AFR and timing. I say this because intake air temps are virtually negligible when compared to combustion temperatures. The effect of intake temps on combustion temps is minimal, and is far more dependent on tuning.

So as long as you can avoid detonation, running the higher psi of the Greddy kit will still cause less wear than running 9psi at your kit, since you are making more torque. Nothing wrong with that, just if you want more power, you gotta put more wear and tear on your motor.

High charge temperatures are more likely to cause detonation, but they do not contribute significantly to Mean cylinder pressure. MEP is found from MEP=F/A, and Force=torque/D. Clearly cylinder pressure is a function directly related to torque. Any good automotive book will tell you engine wear is related to thermal stress, cylinder pressure, and intertial loads. Cylinder pressure being the operative term here.

Thermal stress can be raised due to high intake temps, but not significantly, especially if you're running proper AFR and timing. So as long as you can avoid detonation through tuning, running the higher psi of the Greddy kit will still cause less wear than running 9psi at your kit, since you are making more torque. Nothing wrong with that, just if you want more power, you gotta put more wear and tear on your motor.


With increased charge temps comes increased thermal loads which has a direct impact on coolant temperatures as well as oil temperatures.So now we are talking about higher charge air temps,increased coolant temps and increased oil temps. Increased oil temperature should be a concern for any rotary owner.Once the the temps climb to high........oil breaks down and looses viscosity which means increased wear on the internals. From this standpoint, I think my statement still holds some merit about the engines lifespan.

With increased charge temps comes increased thermal loads which has a direct impact on coolant temperatures as well as oil temperatures.So now we are talking about higher charge air temps,increased coolant temps and increased oil temps. Increased oil temperature should be a concern for any rotary owner.Once the the temps climb to high........oil breaks down and looses viscosity which means increased wear on the internals. From this standpoint, I think my statement still holds some merit about the engines lifespan.

Tim,

Do you guys sell this kit with a Ball bearing turbo? If so, what is the price difference?

Thanks,

Shane

Tim,

Do you guys sell this kit with a Ball bearing turbo? If so, what is the price difference?

Thanks,

Shane

According to their website $600.

http://www.speedforceracing.com/productsmazda_rx8turbokit.php

will the pre tune work with r flash or does it not matter because its a stane alone. im new to turbo but i plan a turbo kit soon

Tim,

Do you guys sell this kit with a Ball bearing turbo? If so, what is the price difference?

Thanks,

Shane


It is $450 more.We lowered the price :yumyum:

will the pre tune work with r flash or does it not matter because its a stane alone. im new to turbo but i plan a turbo kit soon


The TSI will take control of fuel and timing so the r-flash is basically useless.

What type fuel does the initial tuning come with? How much is your dyno tuning to get the most out of this kit?

Also, that is not an accurate statement saying the Renesis will not last as long at 13psi as at 9psi. The Greddy mass flow at 13psi is less than your turbo at 9psi. Inidicated by the power levels. In this particular instance, what matters is cylinder pressure. That is determined by the torque. I suspect that your turbo is outputing more torque, and hence really the motor will last less time with yours.
More torque doesn't necessarily mean more cylinder pressure. In this particular case cylinder pressure might be the same but the Greddy set up suffers from very high backpressure (= torque reduction).

Cylinder pressure can be changed with tuning, octane, boost, rpm, etc, etc, etc... There's alot to it.

Actually I was refering to the correlation between torque and cylinderpressure and not the correlation between cylinderpressure and cylinderpressure.

All of those will change cylinder pressure, but they also will change the torque. Cylinder pressure is directly related to flywheel torque. No question about it. If one goes up, the other will go up.

Here's the formula relating them:

bmep = 2 x Pi x Torque / (Swept Volume)

It's not that simple:
A 4 cycle engine has 4 and not just 1 cycle.
And each cycle adds or substracts torque at the flywheel.

If backpressure is increased, torque will be reduced.

Torque is only added during 1 cycle. The power stroke. That is the only one of interest for this discussion.

If backpressure increases the MEP will decrease. Why? Because there is less fuel and O2 in the chamber. If you look at an Otto cycle pressure diagram you will see the pressure from compression alone is virtually insignificant when compared to the pressure created from combustion. So if you have exhaust back pressure, since it is at a higher pressure than the intake charge, it will result in an increased cylinder pressure up until combustion takes place. During and after combustion, the cylinder pressure will be lower due to the exhaust charge contamination using space that would otherwise be occupied by O2 and fuel. In other words, the combustion of fuel will create far more pressure than the existance of exhaust gasses in the chamber. So the MEP will be down as will torque.

I'm sorry, but this is the very interest of this discussion:

4 cycles and each cycle adds or substracts torque:
1. Intake subtracts torque
2. Compression subtracts torque
3. Combustion adds torque
4. Exhaust subtracts torque

Backpressure is driving the turbo and not some imp. And the piston or in this case the rotor has to work against this backpressure. If the rotor has to work against this pressure it needs torque and it takes this torque from the flywheel.

This is why 2 engines with the same MEP but different backpressure can have different torque figures.

Besides the Renesis does not have port overlap, which means backpressure cannot displace intake air to the level it could if it had overlap.

how many mpg?

I'm sorry, but this is the very interest of this discussion:

4 cycles and each cycle adds or substracts torque:
1. Intake subtracts torque
2. Compression subtracts torque
3. Combustion adds torque
4. Exhaust subtracts torque


I know this, but what does it have to do with anything. We are discussing the torque shown on a dyno chart versus cylinder pressure. That torque is only created during the combustion cycle.


Backpressure is driving the turbo and not some imp. And the piston or in this case the rotor has to work against this backpressure. If the rotor has to work against this pressure it needs torque and it takes this torque from the flywheel.

This is why 2 engines with the same MEP but different backpressure can have different torque figures.


How do you know this? When have you had access to equipment capable of measuring the MEP on two identical engines and where able to vary just backpressure?


Besides the Renesis does not have port overlap, which means backpressure cannot displace intake air to the level it could if it had overlap.

Not sure what this has to do with our discussion on the relationship between torque and CP. This is a general relationship and not Renesis specific.

I quoted the formula for computing torque from MEP above. Did you see any variable in that formula accounting for backpressure? No, because the relationship between the two is not dependent on it.

I know this, but what does it have to do with anything. We are discussing the torque shown on a dyno chart versus cylinder pressure. That torque is only created during the combustion cycle.

Obviously you still do not understand. Again there is a reason why it is called a 4 cycle engine and not a 1 cycle engine. Torque shown on your dyno chart is a result of:
Comubstion cycle
minus intake cycle
minus compression cycle
minus exhaust cycle

If you increase backpressure you reduce torque shown on your dyno chart.


How do you know this? When have you had access to equipment capable of measuring the MEP on two identical engines and where able to vary just backpressure?
This is basics. Are you seriously claiming that you don't believe that backpressure does have an influence on torque and power? If you don't believe it, I suggest to put a Banana in your exhaust and see what happens. The banana will increase backpressure and reduce torque.


I quoted the formula for computing torque from MEP above. Did you see any variable in that formula accounting for backpressure?
This formula is an approximation for a naturally aspirated engines. If it was all that simple we wouldn't have expensive engine simulation software and of course engine test labs wouldn't need pressure sensors measuring the pressure in the combustion chamber. R&D could save millions, if they could just use your formula.

smarty pants...

Turbo= GUD!! :cwm27:

I honestly don't even think you read my post.

I completely agree that increased backpressure will result in less torque, as I stated here:

So the MEP will be down as will torque.

I don't think you understand what I'm trying to state. I'm not stating you can calculate the exact torque if you knew the instantaneous cylinder pressure. I'm saying that one is proportional to the other. The expensive simulation software gives actual approximated values for those.

Seriously, I don't even know why I'm having this conversation. How would torque not be proportional to cylinder pressure? What else would push the piston down? If you can describe some other significant force that's involved besides the force from combustion, I would be very interested. If you have more force pushing down the piston, then you will have more torque, if you have less force pushing down on the piston then you will have less torque. I don't know how you're going to argue with this.

Take 5 min and do a google search on MEP vs torque. Find me 1 reference stating you are right.

Here's my list of references:
http://www.google.com/search?hl=en&q=mep+vs+torque

Pick one.

I completely agree that increased backpressure will result in less torque
Yes but are also claiming that increased backpressure will result in less MEP and that's why it is producing less torque. They do not simply go hand in hand. And even if they did increased backpressure will ALWAYS reduce torque regardless whether MEP is the same or not.


I still don't know what you're trying to say? I know this, as I've already said. I don't care about any of those other cycles. The torque is created, or the positive addition, or the perceived torque, or however you want me to word it is only added during combustion. Can you explain why you keep mentioning this.
Since we want to increase actual torque shown on the dyno or perceived on the wheels, we have to be concerned about factors that lead to torque reduction as well.

The question was whether this Turbo has more MEP than the Greddy, because torque is higher. And I'm saying that this is not necessarily the case because backpressure of the Greddy set up might easily be double than on this set up.
The Greddy set up at this high boost pressure and efficiency range might easily require 50 HP to generate that boost level at this airflow (Power=p*V). Keep in mind the overall efficiency of a turbo (turbine and compressor) is barely 50% at its optimal operating point.
These 50 HPs are coming from the engine in the form of backpressure and directly lead to a power reduction at the flywheel.

How would torque not be proportional to cylinder pressure?
No one claims that torque ist not proportional to cylinder pressure on a given engine, but AGAIN it is not the only factor. There are 4 cycles and NOT just one. And each cycle affects torque measured at the flywheel. And this is not even the whole story. Internal friction, oil pump, water pump, alternator and what not do also reduce torque measured at the flywheel. I don't need references to know that cylinder pressure is not the only parameter affecting torque.
I'm sorry, but this is really far too basic to even have a debate about.

If backpressure would not affect torque it would mean that backpressure can be had for free and is therefore not relevant. And in this case turbo efficiency would not matter either.

No one claims that torque ist not proportional to cylinder pressure on a given engine, but AGAIN it is not the only factor. There are 4 cycles and NOT just one. And each cycle affects torque measured at the flywheel. And this is not even the whole story. Internal friction, oil pump, water pump, alternator and what not do also reduce torque measured at the flywheel. I don't need references to know that cylinder pressure is not the only parameter affecting torque.

I'm not saying that MEP is the only factor by any means. I'm just saying in general if MEP goes up, torque will go up. Much like the conversion from flywheel hp to wheel hp. There are many thing affecting that conversion (friction, intertia..), but in general the two are proportional. If flywheel HP goes up, wheel HP goes up.

Backpressure is a misused word in the context of engine performance. This may or may not be in the context of this discussion but I'll deal with it anyways since the term was mentioned. You never want backpressure. Here's why. You want velocity. A certain velocity of air will help pull a chamber clean, charge an intake, or spin a turbocharger. The term backpressure is commonly used but it is really a misinterpretation of what is going on. For any given load or rpm, there is a certain optimum air velocity. The perfect velocity for 3000 rpm is no good for anything above this point as is true with any other rpm. If we had a pipe sized for max velocity at 3000 rpm, that rpm would be good but we would introduce backpressure above this point which can only hurt performance. Backpressure is bad. So we say we want less backpressure. Want less where? There is an rpm where you don't have any for any given sized pipe. The terms backpressure and velocity are all based on a world of compromise. You don't size something for 8000 rpm but expect it to be optimum at 3000. Sure you'd have "no backpressure" down there but you also have no velocity and that's what counts. You want as little backpressure as possible while still retaining high velocity needed for optimum performance. This applies from everything from intake design, exhaust design, to turbocharger sizing. When most people say they need to add backpressure, they really mean they have too little velocity and need to add it at that spot. Of course above that point will suffer somewhat. It's all a tradeoff.

A turbocharger does not run off of backpressure. It runs off of flow. It doesn't even run off of heat. A turbocharger does introduce backpressure into the exhaust manifold and engine though since it is a restriction. At the flow level it isn't a restriction, it also isn't spooling. Restrictions in the exhaust raise the combustion temperatures of the engine and also raise the likelyhood of detonation. The key to turbo sizing is to get an exhaust housing sized so that it spools up faily quick but at the same time doesn't choke off the motor on the top end any more than neccessary.

To understand the pressures inside a turbo exhaust housing is as easy as just thinking about how air flows through it. The housings takes a certain volume of exhaust area and chokes it down. This speeds up the flow through the turbo to get the wheel moving. Remember the wheel moves based on flow, not pressure. Faster flow is faster spool. What pressure it is at is nearly irrelevant. What happens when you speed air up as is happening inside the exhaust housing? You lower it's pressure. This means you create a high pressure at the entrance to the turbo which in turn affects the flow of gasses out of the engine as well as tries to keep some in it.

I understand you guys are talking about MEP vs torque but I wanted to get the backpressure thing cleared up.

But flow is proportional to pressure. (More pressure difference = more flow or no pressure difference = no flow).

pressure = density/2*velocity^2 (according to Bernoulli).

That's understood. Flow is proportional to pressure but pressure is not proportional to flow which is why many get them messed up. My air compressor tank in my garage is sitting at 120 psi. There is no flow. It isn't pressure doing the work, it's flow. It is understood that you can't have flow without pressure but that only works one way. You can have pressure without flow. Just because you added pressure does not mean you added flow.

In the case of the turbine massflow does work and in case of a piston pressure times Volume does work. (At least that's how we apply these models, since one model works better for one application and vice versa).

But at the end work is work. Work = pressure*Volume = mass/2 *velocity^2.

You are correct, the amount of work being done is something that you can figure out that way. What you can't determine based on that is how much you are getting for all the effort. You can show how much work an engine is doing to push air out of a pipe but you can't show how much power it is making based on that or the efficiency of it. Once you hit an average (not peak) airspeed velocity of .6 mach throught the system, efficiency falls off the planet. You can show how much work is being done to a turbo based on exhaust flow through it but you can't show how the turbo is responding to it.

If all you are interested is how much work it takes to do something then that's fine. You should be able to tell how much power it takes to run a turbo or a supercharger this way. That is good information to know. You just can't show how much they are producing based on it alone without knowing alot of other things.

That is a very good formula to know though.

Which also means that a turbo run over its operating point might even create more harming backpressure not just because the turbine is past its efficiency range but the whole set up including housing cannot convert that pressure and temperature into mechanical work (and heats housing and header instead).

326 hp eh..... more than enough power for drifting.... >_< .... lately its been raining here and i get of work at 3am and just drift every right/left turns at intersections.... so beautiful.... oh yeah anyway, how fast is the 1/4 time for that?

Attention people in a 10mile radius of the above poster. Make sure to be in your home and off the road by 2:45am.

Seriously though, you'll be in brothervoodoo's gallery soon enough.

I don't like the curve of the power..I have seen alot more straigh lines..I ll put my graph soon from which you will be amazed but i don't have so many hps..I just want you to see what i mean with the "straight" line..

Although very good numbers..Keep it up..

In the case of the turbine massflow does work and in case of a piston pressure times Volume does work. (At least that's how we apply these models, since one model works better for one application and vice versa).

But at the end work is work. Work = pressure*Volume = mass/2 *velocity^2.

Ummm... Your formulae aren't technically correct. You are confusing work and energy. Work done is equal to a change in energy. P*V is a measure of potential energy. 1/2mv^2 is kinetic energy.

You've got a point. Actually, I should have said power instead of work or energy.

Power=p*V=m*v^2
and with Volume and mass per time unit. (Meaning a point above V and a point above m).

um wat can i contribute to this... u guys r hella smart i am just tuning in and learning all this crazy talk of physics... :Eyecrazy:

I don't like the curve of the power..I have seen alot more straigh lines..I ll put my graph soon from which you will be amazed but i don't have so many hps..I just want you to see what i mean with the "straight" line..

Although very good numbers..Keep it up..


You cant have your cake and eat it too.If you use a larger turbo that makes more horsepower, your power and torque curves shift to the right. A ball-bearing turbo will help give you the best of both worlds but still expect some compromise when you are dealing with a turbocharger this large.


Tim

Attention people in a 10mile radius of the above poster. Make sure to be in your home and off the road by 2:45am.

Seriously though, you'll be in brothervoodoo's gallery soon enough.http://www.rx8club.com/attachment.php?attachmentid=73856&stc=1

:bootyshak

LMAO. Glad im not there!

Haha...classic.

Mazda North America is just barely off that map by literally a couple of blocks.

The radius of the "DRIFT ZONE" is only about 4 miles in my map. If i did the full 10mi that Moostafa suggested, many people would have been in danger.

No thanks,I'll stay in Vegas

Yup, I'll have to go to sleep early at the next sevenstock.