is it worth it to turbo/sc
09-17-2006, 01:31 PM
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is it worth it to turbo/sc
heres my question: ALl in all is it worth the money,hp gains,work,tuning to make an rx-8 turbo/sc if you want to have a lot of speed or is it better to just mildy tune the 8 have it is a daily driver and get sumthin else to really get alot of power out of(by alot of power im meaning around 500hp.) just want some opinions on this/proof if possible that it is or isnt worth it.and lets not bash each 
other i wanna see both sides to the argument.
other i wanna see both sides to the argument.
09-17-2006, 02:02 PM
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Depends how you value your money and time, also on what you want out of your vehicle. If you have the extra cash laying around then I would say it's worth it. But if you don't and you're barley making meets end then no.
09-17-2006, 02:11 PM
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09-17-2006, 02:39 PM
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First, Mazda has done about the best they could given what they have to work with in terms of emissions, fuel availability, and durability. So anything that changes, changes the factors above.
If you want 500 HP buy something else.
For reference sake say the 238HP claimed is accurate. I know wheel dynos show 180HP, and most cars only lose about 15% of their power to drivetrain losses so in theory it really only has about 210 HP anyway. But I'll use 238 HP for reference.
A turbo at 5 PSI could boost that to about 280 HP, but the powerband will change. You'll lose top end, about 1500 RPM, and gain some bottom end, just not nearly as wide of a powerband. At least if you go by the dyno sheets provided and "recalibrate" for the claimed 238 HP. Fuel mileage will go to hell, and you'll find new little problems appear with time such as air and oil leaks. It is possible to make mods to see as much as 12PSI and even more, but not without creating more problems at a much faster rate. Simply put the candle that burns twice as bright only lasts half as long. And this candle likes to throw a lof heat away so expect pathetic fuel consumption.
Now there are a few altenatives that don't cost nearly as much but give pretty decent results.
From most accounts the RB Airbox does a good job at improving some of the throttle repsonse and adds a couple ponies at peak, and supposedly more off peak. Iv'e built a Mazdaspeed CAI clone and it definately adds more at 4000 RPM then 8000 RPM.
If emissions aren't a concern, the cat bypass pipe is probably one of the best solutions, if you can get past the CEL warnings. I think there are one or two little black boxes that may work for that, and at $350 or so it's said to be worth about 20 HP. Just a bit louder if you can stand for that. I'm surprised no one has added a glasspack as a resonator for that yet.
That gets you to about 260 HP.
Now if you really want some cheap HP get some real fuel.
Phillips TT105 is best at 110 octane and 2.7% oxygenation.
Phillips Race Fuels
TT101 is pretty good stuff too.
What makes these fuels work better then pump gas is the following;
1) They contain oxygen. 2.7% by weight goes a long way - and it will take several start-from-cold cycles for the ECU to figure out you need a richer mixture. Typically on the 2 stroke stuff we've done a lot of dyno testing on, 2.7% adds about 10-15% more power across the powerband. Say 24HP on a mazda although I haven't done any dyno testing on the Mazda to confirm that.
2) They have a higher heat of transformation. In simple terms vaporization results in a cooler charge (more density) - and from the 2 stroke testing thats another 5% over pump fuel - add another 12 HP.
3) Higher octane. That in itself won't give you any more power unless you alter the timing, and frankly I don't have a clue what some careful tuning can give you there.
That translates to another 36HP, in addition to the 260 HP from the intake & exhaust. 296 HP - compared to the 280 HP from a turbo.
Not bad - although the fuel runs about $5.50 a gallon by the 55 gallon bbl. On the other hand, skip the $3500 you'll spend on a turbo and buy race fuel, and you'll get it for about $4.50 a gallon - about 15 bbls or 825 gallons of gas. Hey ya gotta buy gas anyway.
Finally if you want a real treat add a lightweight flywheel. On an inetria dyno these seem to show anywere from 5%-15% gains in acceleration HP depending on the gear you're in. better yet they don't take away from durability of fuel mileage.
That gets you into the 300HP range without really sacrificing durability although you will spend more on fuel.
If you want 500 HP buy something else.
For reference sake say the 238HP claimed is accurate. I know wheel dynos show 180HP, and most cars only lose about 15% of their power to drivetrain losses so in theory it really only has about 210 HP anyway. But I'll use 238 HP for reference.
A turbo at 5 PSI could boost that to about 280 HP, but the powerband will change. You'll lose top end, about 1500 RPM, and gain some bottom end, just not nearly as wide of a powerband. At least if you go by the dyno sheets provided and "recalibrate" for the claimed 238 HP. Fuel mileage will go to hell, and you'll find new little problems appear with time such as air and oil leaks. It is possible to make mods to see as much as 12PSI and even more, but not without creating more problems at a much faster rate. Simply put the candle that burns twice as bright only lasts half as long. And this candle likes to throw a lof heat away so expect pathetic fuel consumption.
Now there are a few altenatives that don't cost nearly as much but give pretty decent results.
From most accounts the RB Airbox does a good job at improving some of the throttle repsonse and adds a couple ponies at peak, and supposedly more off peak. Iv'e built a Mazdaspeed CAI clone and it definately adds more at 4000 RPM then 8000 RPM.
If emissions aren't a concern, the cat bypass pipe is probably one of the best solutions, if you can get past the CEL warnings. I think there are one or two little black boxes that may work for that, and at $350 or so it's said to be worth about 20 HP. Just a bit louder if you can stand for that. I'm surprised no one has added a glasspack as a resonator for that yet.
That gets you to about 260 HP.
Now if you really want some cheap HP get some real fuel.
Phillips TT105 is best at 110 octane and 2.7% oxygenation.
Phillips Race Fuels
TT101 is pretty good stuff too.
What makes these fuels work better then pump gas is the following;
1) They contain oxygen. 2.7% by weight goes a long way - and it will take several start-from-cold cycles for the ECU to figure out you need a richer mixture. Typically on the 2 stroke stuff we've done a lot of dyno testing on, 2.7% adds about 10-15% more power across the powerband. Say 24HP on a mazda although I haven't done any dyno testing on the Mazda to confirm that.
2) They have a higher heat of transformation. In simple terms vaporization results in a cooler charge (more density) - and from the 2 stroke testing thats another 5% over pump fuel - add another 12 HP.
3) Higher octane. That in itself won't give you any more power unless you alter the timing, and frankly I don't have a clue what some careful tuning can give you there.
That translates to another 36HP, in addition to the 260 HP from the intake & exhaust. 296 HP - compared to the 280 HP from a turbo.
Not bad - although the fuel runs about $5.50 a gallon by the 55 gallon bbl. On the other hand, skip the $3500 you'll spend on a turbo and buy race fuel, and you'll get it for about $4.50 a gallon - about 15 bbls or 825 gallons of gas. Hey ya gotta buy gas anyway.
Finally if you want a real treat add a lightweight flywheel. On an inetria dyno these seem to show anywere from 5%-15% gains in acceleration HP depending on the gear you're in. better yet they don't take away from durability of fuel mileage.
That gets you into the 300HP range without really sacrificing durability although you will spend more on fuel.
09-17-2006, 02:50 PM
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wow thanks alot for the info kartweb sounds like ya know your stuff.after reading it tho im pretty sure im not goin to go with a turbo setup on the 8 maybe just the flywheel and intake exhaust parts, so thx again for the help with that.id still like to hear what anyone else thinks though.
09-17-2006, 03:28 PM
#8
Yeah, unfortunately Kartweb's speculation on all that is completely incorrect.
Nice try, though.
Race fuel does not produce any more power on its own under any circumstances.
A mid-pipe produces absolutely minimal gains by itself. Same goes for exhaust.
CAIs, for the most part, actually lose power on the RX-8.
The only way to get the RX-8 into the range of 300 RWHP is via forced induction. The other "mods" as indicated then start to have a cumulative effect that is measurable.
However, all of those mods in addition to some fairly extreme engine work could get you close, I suppose. Porting and some decent engine management could work, but you would loose your flat torque curve.
BTW - the turbo does NOT sacrifice the torque curve - it simply amplifies it. There is no power lost up top or anywhere else. It is all in the tuning.
Nice try, though.
Race fuel does not produce any more power on its own under any circumstances.
A mid-pipe produces absolutely minimal gains by itself. Same goes for exhaust.
CAIs, for the most part, actually lose power on the RX-8.
The only way to get the RX-8 into the range of 300 RWHP is via forced induction. The other "mods" as indicated then start to have a cumulative effect that is measurable.
However, all of those mods in addition to some fairly extreme engine work could get you close, I suppose. Porting and some decent engine management could work, but you would loose your flat torque curve.
BTW - the turbo does NOT sacrifice the torque curve - it simply amplifies it. There is no power lost up top or anywhere else. It is all in the tuning.
09-17-2006, 04:09 PM
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Obviously none of doubting Thomas's have ever worked with fuels let alone mixing their own motor cocktails using Benzene, Toulene, Acetone, Propylene Oxide, and few random free-radical oxygenates to boot. I've spent a couple hundred hours dyno testing fuels - granted on 2 strokes, but I've got experience at it just the same.
Here is just a small sample of what I've published on fuel over the last ten years;
2 Stroke Fuel Summary
I'm not new to rotaries either. This just happens to be the first one thats not mounted in a tube frame chassis and has a license plate. My first rotary was in chassis #07 in 1983.
Here is just a small sample of what I've published on fuel over the last ten years;
2 Stroke Fuel Summary
I'm not new to rotaries either. This just happens to be the first one thats not mounted in a tube frame chassis and has a license plate. My first rotary was in chassis #07 in 1983.
Last edited by kartweb; 09-17-2006 at 04:12 PM.
09-17-2006, 04:20 PM
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Originally Posted by MazdaManiac
Porting and some decent engine management could work, but you would loose your flat torque curve.
BTW - the turbo does NOT sacrifice the torque curve - it simply amplifies it.
BTW - the turbo does NOT sacrifice the torque curve - it simply amplifies it.
09-17-2006, 04:28 PM
#12
I think what truste is asking for is real world driving impressions of turbo powered 8s vs stock & what compromises you have to make to achieve those power levels.
I think I have done as much as anyone here as far as N/A mods go and can say the car is definately more fun to drive without any real compromises (although LW fly does make it a bit harder to drive smoothly).
However , it is probably quite tame when compared to a FI 8 & if you want that kind of a buzz - FI is the only way you will get it . If you read a few turbo threads you will find its not all plain sailing though .
I think I have done as much as anyone here as far as N/A mods go and can say the car is definately more fun to drive without any real compromises (although LW fly does make it a bit harder to drive smoothly).
However , it is probably quite tame when compared to a FI 8 & if you want that kind of a buzz - FI is the only way you will get it . If you read a few turbo threads you will find its not all plain sailing though .
09-17-2006, 05:17 PM
#15
Originally Posted by kartweb
That gets you into the 300HP range without really sacrificing durability although you will spend more on fuel.
Most of us here HAVE gone the CAI, catless midpipe, aftermarket catback, fuel management, etc. route, and while the car is a little quicker, the total gains usually brings you to around 200 whp area, a far cry from 300 whp. After a while, everyone here reaches the same conclusion - you must go FI if you want gains with the RX-8. It was designed really well from the factory and the usual methods for hp are dead ends when NA.
09-17-2006, 06:17 PM
#16
Originally Posted by kartweb
Obviously none of doubting Thomas's have ever worked with fuels let alone mixing their own motor cocktails using Benzene, Toulene, Acetone, Propylene Oxide, and few random free-radical oxygenates to boot.
Originally Posted by kartweb
Well, make your mind up. It either does or doesn't.
However, all of those mods in addition to some fairly extreme engine work could get you close, I suppose. Porting and some decent engine management could work, but you would loose your flat torque curve.
BTW - the turbo does NOT sacrifice the torque curve - it simply amplifies it.
BTW - the turbo does NOT sacrifice the torque curve - it simply amplifies it.
Originally Posted by Razz1
Ja, but Super Charger are the way to go:
Just wait until Seven Stock.
You'll see what I mean.
Just wait until Seven Stock.
You'll see what I mean.
Originally Posted by kartweb
I've spent a couple hundred hours dyno testing fuels - granted on 2 strokes, but I've got experience at it just the same.
Now, if you want to setup a Renesis to run on an alternative fuel, you can use nitromethane or something with a higher caloric output. However, on gasoline, you will not derive enough thermal advantage on any formulation that can be utilized by a normal RX-8.
Even with engine management, there is a limit to how much more power is available with extreme ignition timing. That is what I was discussing in the other thread, but you didn't understand that one either.
BTW - if you want a real education on gasoline, read the gasoline FAQ on my page that was written by Bruce Hamilton.
Yet another page-topper for me. That makes two dozen in a month!
Last edited by MazdaManiac; 09-17-2006 at 06:22 PM.
09-17-2006, 07:16 PM
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Originally Posted by mysql101
Most of us here HAVE gone the CAI, catless midpipe, aftermarket catback, fuel management, etc. route, and while the car is a little quicker, the total gains usually brings you to around 200 whp area, a far cry from 300 whp.
For reference sake say the 238HP claimed is accurate. I know wheel dynos show 180HP, and most cars only lose about 15% of their power to drivetrain losses so in theory it really only has about 210 HP anyway. But I'll use 238 HP for reference.
What I find surprising is how little the "hot rod" minds of today know about fuel. While I'm not an advocate of Nitromethane, ask any experienced drag racer just how much power Nitro adds over pump gas. Just where do you think 3500 HP comes from in a 500 cubic inch motor that produces 5500 HP?
Feed the motor more oxygen. The typical stuff like MBTE or alky doesn't go very far - maybe .2-.3% O2 when mixed to the limit with gas. Some race gas has oxygenation, some doesn't. What I spec'd does.
Most of the "hot rod" heads barely know anything about gasoline. They think it's all about octane. 3/4's of them think higher octane "slows" combustion. It doesn't slow combustion. It merely raises the point at which spontaneous combustion occurs.
Heat of transformation is one that loses just about every non-technical hot rod head. When a liquid turns to a vapor there is an exchange of heat and the vapor cools things off. Pour some pump gas in a bowl put in a thermometer and let it evaporate. After a while the temp drops a few degrees. Now try it with one of the two fuels I spec'd - and the temp drops by about double. I've done some flow tests with Keihn carbs and where pump gas will drop the air-fuel temp by about 25° F, T105 drops it by about 60°F. Any hot rod heads care to tell us why they intercool turbos? If you answered CHARGE DENSITY you'll get a blue star.
Now back to O2 a moment;
NITROBENZENE C6H5NO2 is an inflammable, yellow, oily liquid with a strong odor of almonds. Kind of explains the sweet smell of this stuff. You'll find that in T101/5. Can any of you hot rod heads earn another blue star by telling us what the content by weight O2 is in this stuff?
By contrast;
NITROMETHANE CH3NO2 is an inflammable water-clear liquid with a mild odor, containing approximately 53% by weight of oxygen. Water will mix with nitromethane to the extent of 2.5% only, by volume. You won't find nitro in T101/5.
Now lets talk turbos a moment. How much extra O2 is in 5 lbs of boost? Well if it's the same temperature you could say about 30% - but it's not the same temp. It's a good bit hotter - add 100° temp and it's about 20%. Whats more is you've just added the equivalent of about 3 mufflers in series for the attendant increase in back pressure. But thats just the surface - how much detonation does it create? That depends on the length of time under WOT. Give it a couple dyno pulls and you're still somewhat safe providing you have good fuel and retarded ignition. A single drag run, and you're still probably OK. Now try a few laps on a road course - with maybe a 3000+ foot straight like Road Atlanta - detonation city. Honda makes a nifty det counter for GP bikes, I've got 2 of them. Or you can use a Mychron Plug T-Couple - just wait untl plug body temp sudddenly jumps from 215° to 240° in about 4-5 seconds - thats detonation.
Turbos are great when the SYSTEM is designed for them. The RX8 system is sort of cobbled together with most turbo kits, and no question they make power - but for how long?
I don't have anything against turbos. The original question came from someone who was looking for 500 HP. I gave him an answer that few of you were prepared to hear.
BTW, anyone who wants to drag race me on an 1/8th mile is welcome to; I'll bring my 8 cubic inches and you bring your car.
09-17-2006, 07:38 PM
#20
Originally Posted by kartweb
Read carefully;
Does that say Wheel HP ?
What I find surprising is how little the "hot rod" minds of today know about fuel.
Does that say Wheel HP ?
What I find surprising is how little the "hot rod" minds of today know about fuel.
I'm probably not going to spend any time right now explaining all of the little mistakes you made in that post - or any of the larger misconceptions either. There is just too much misdirection.
Really, they all go in one direction - missing the point.
I appreciate that you have done your chemistry homework, but the fact is none of it is useful on the street in a normal application.
I especially like it whe you say things like this:
Originally Posted by kartweb
anyone who wants to drag race me on an 1/8th mile is welcome to; I'll bring my 8 cubic inches and you bring your car.
Stop bringing up oranges in an apple orchard.
Originally Posted by kartweb
The original question came from someone who was looking for 500 HP. I gave him an answer that few of you were prepared to hear.
Last edited by MazdaManiac; 09-17-2006 at 07:41 PM.
09-17-2006, 11:02 PM
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Originally Posted by MazdaManiac
I appreciate that you have done your chemistry homework, but the fact is none of it is useful on the street in a normal application.
As far as being practical for the street what would you recommend I run in a 396 that came from the factory in 1966 with 11:1 compression? Usually I run Phillips T111. But i only drive it about 300 miles a year too. (My neighbor calls it "Corvette Perfume" - the nitrobenzene smells really sweet - and not a spec of sulphur in the fuel.)
I think it's pretty comical to see folks who want to own something different like a rotary yet can't deal with something they have no knowledge and experience with like fuel chemistry. If you take my laughter as anger then you may be a little confused. It really doesn't matter whose papers you post on your own website, the question is how many have you written and published on your own? How many subscribers are willing to pay to get access to the technical content on your website?
How about we make it a 1/4 mile and you strap on an extra 2200 lbs on that sled to make it even?
How about I add 3000 lbs and 384 cubic inches? BTW, both of them turn the same times in a 1/4 mile - one gets to 100 MPH a whole lot faster though.
Persoanlly I like my RX8 like it is.
09-17-2006, 11:29 PM
#22
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Fuel aside, there is no way that changes in the exhaust could yield you 20+ hp. Racing Beat dyno'd the car with no exhaust and it yielded 8 hp. No matter what you put on there, it's only going to lose hp from that point. A N/A intake will never yield more than a couple horsepower on this engine. So mayybee just maybe you could get 10 hp with intake+exhaust, putting you at a theoretical 242 at the crank (using the 232 advertised by mazda).
To say that you can add 36 horsepower by using special gas is just silly.
To say that you can add 36 horsepower by using special gas is just silly.
