Peripheral Port Renesis dyno's
 

This is just what it sounds like. This is a Renesis that has had peripheral ports cut into it. The side intake ports are no longer used. The side exhaust port configuration is retained. We've been curious about it. Here it is.

The results are very interesting. As predicted, power does go up. However it isn't anywhere near what a peripheral intake and exhaust engines can do. It is interesting to note how much the powerband changes between 19" in length and 22" in length. Look at what rpm it makes more power than the stock engine.

http://www.rotaryeng.net/RX8PPB-Stock-RX8.jpg

http://www.rotaryeng.net/RX8PP264a-Stock-RX8.jpg

Here's how they built it:

http://www.rotaryeng.net/Welded-steel-p-port.html

263 for PP? well, the graph does make more power, much faster than the stock even if the peak hp is a little disappointing

It should be pointed out that the most powerful periperpheral ported engines make their peak power up over 9K so this may actually not be that bad.

The 19" runner graph shows power being greater than stock above 6100 rpm. That's pretty high. If you look at the extreme left though it implies more power below 5000 rpm as well. If the tuning trend could be extended down lower, it would probably make more power between about 3500-5000 rpm as well. That is assuming that these runs didn't just start at 5K but rather the graph does.

Here's a dyno of a conventional all peripheral port (non Renesis) engine with 24.5" long runners. A shorter runner setup should be more powerful. This shows a peak power level of about 245 hp which is more than the shorter (22") intake runner p-port Renesis.

http://www.rotaryeng.net/Weber58-24....yno-curve2.jpg

This implies that the peripheral exhaust port is still superior when used with a peripheral intake port. I'd tend to agree as you need to have similar timing characteristics between intake and exhaust port to get full potential.

Here it is on the dyno at Mazdatrix:

http://www.rotaryeng.net/Idle3.wmv

http://www.rotaryeng.net/Standoff3.wmv

????? You are contradicting yourself.

Wow, that's a lot of work for 60 HP.
Does it idle?

You just said those sheets are wrong then you said you trust it far more than others.

Thanks for the post RG! I'd never actualy seen a peripheral port before :)

It's idling around 1300 rpm. Here in Texas your car needs to idle below 1000 rpm to pass inspection. This engine is also using a carb and not fuel injection so there is probably some power to be had and a lower idle that could be obtained.

I +1 on that

and from what I've read on here, PP renny = not safe with turbo.......so......wtf

Actually they do cross at 5252. The stock dyno lines are hand drawn in for rough reference only.

its the problem with the graphing not the results. they are not scaled the same, ray.. we see that allot with dyno plots

dang... hp goes up but so does tq. for someone who isn't rolling in cash, this is well worth it if u already have the engine out or replacing one... but to pay for labor for all that mmm~

not to mention that some renesis' with just a smart rebuild and masterful tuning have seen 262 on an engine dyno. so the Pport seems hardly worth it

Good luck trying to make this work with the stock ecu. I guess it could be done. You would need a new intake manifold though. It's not something I'd do to my engine. I'm still convinced that the all side port rotary is the perfect street combination.

well it's BS from the sense that the PP exhaust was modified extensively in other areas, so it's hardly a relative comparison to a bone stock Renesis for the point at hand

How are you still convinced??? It makes very little power when modified in N/A form (compared to previous gen) and it doesn't run any better than the old 13b's. :lol:

Look at it again. It doesn't have a peripheral port exhaust. It's all side port exhaust. Only the intake ports are peripheral.

Keep in mind this engine isn't for a car. It's for an airplane. He only cares about what it does at 1 particular rpm and doesn't need a big powerband.

I always thought the exhaust ports were more of a restriction than the intake ports? I understand that there is power to be had by improving the intake ports but couldn't we see a larger increase in power from exhaust porting?

Forgive me as I am not well versed in porting and its pros and cons...

They are. There's more to power than pure static flow numbers. Many people don't understand this.

aaack, my bad, guess I don't see any need for doing such on the intake as opposed to the exhaust

sideways oval would be better than a round port IMO, harder to make though

I know who he is and what he's doing, not impressive at all considering those are flywheel #s :dunno:

Those peak power numbers aren't impressive if all you are looking at is the peak. Look at what rpm those peaks occur at though compared to engines that make more power and it really isn't bad.

And its not very good for the kind of port that was done.

How many other peripheral intake, side exhaust port engines have you seen? I stated earlier that it was lower in power compared to an all p-port engine. It should be. The exhaust port timing is all wrong in relation to the intake timing.

How are the corner and apex seals dealing with the perip port? Are OEM seals being used?

My apologizes I missed that statement.

I know of only 1 other one but it didn't hold up. The owner switched to 13brew PP config and now making 340 rwhp @ 9500rpm lol.

That's what is so incredible about these little engines!

I'd be curious to see how much power he was making at 7500 and compare it to what this engine made there.

Would be nice but I'm sure the 16x makes more in factory trim. lol :lol:

Displacement is a good thing.

it better, if not mazda will fall

Well the 16x should be an improvement without any doubt just based on the displacement increase alone without Direct Injection or the Larger Ports. (assuming emissions are met) Now include DI and LP along with better fuel economy ...how can Failure even cross your mind? RX8 sold solely on marketing so improve it in all areas a bit and why would it not sell well again?

If your referring to the RX7 well that is a different story, they have so many directions they can take the car but which will they choose. I'm sure R&D will figure it out and lets hope its not the way of the new Miata. :lol:

i was merely saying that the 16X BETTER be better, if not mazda would be failing big time because of all the reasons you listed

i highly doubt it would though, but still, I highly doubted mazda rx8 sales could have gotten any lower and here we are now

Not exactly a business major, are you?

Kind of makes you wonder why mazda doesn't just make a new small suv and stuff a 4 rotor in it.

1) would get around emissions laws for sedans/coupes
2) could be easily swapped into the 8 or 7 or whatever

Interesting they used 87 Octane...

87 makes the highest power on a N/A rotary

Really? Any proof of this? Why is it recommended to put in 91 or higher.

Mazsport Scott tuned the N/A for 91 93 87 and 89, he found that 87 made more power than higher octane gases.

91 is used to combat the high temps the engine experiences in stop and go daily driving and fouling of the plugs, etc.

Naturally aspirated rotaries have always loved low octane fuel. The only reason the Renesis doesn't doesn't have anything to do with the engine. It has everything to do with the tuning. Retune a Renesis and it would love low octane too.

PP on demand
 

I've always wondered whether a PP + side intake rotary would work.
That is, at low speeds a butterfly valve in the PP intake runner is shut and the engine works just like a regular side intake engine, then above a certain point the valve opens and the PP starts doing its dirty job... It could possibly be used instead of the aux side intake port.

I know that a similar setup was used many years ago for a racing engine (possibly a 12A), but would it be feasible for a road engine?
Also, would a similar butterfly valve controlled exhaust Peripherial port be possible? I've been thinking about it for a while, and while carbon deposits may be an issue, the actuators could be instructed to flip the valve 180° every time the engine goes to deceleration fuel cut-off, so that the valve "sweeps" its seat and keeps it clean. Any thoughts?

Ain't that the truth. The engine is a dynamic environment -- it's not about how big you can make a port or whether or not you can cut it so big that you can shove a lemon through it. Bigger isn't better and frequently it produces negative, back-peddling results. The largest aspect is velocity -- how fast can the charge (air and fuel combination prior to compression) move and swim through your intake into the compression stroke. The second thing is the utilization of reversion -- when the rotor closes the intake port/when the intake valve on a piston motor is shut the charge slams into it and reverts its way backwards (all fluids and gasses take the path of least resistance) creating an effect called reversion which, when changing intake runner diameter and length, can have a positive effect on higher RPM engine operation.

MazaManiac, it's not about peak power; it's not about spending (x) dollars on a setup to "get 60hp". It's about the torque and horsepower band, it's about when torque begins to rise and how quickly it rises per (x) RPM, and it's about peak torque and horsepower. Not to mention it's a nice experiment that gives some very useful data that's worth much more than the money spent to do it.

B

I understand what you're saying Staticlag, but I wouldn't think of it in terms of "combating" but instead consider it more as a part (not only a part but a critical part) of a system with several parts that have to be "well-balanced" concerning the goal of the system (creating (x) power or producing (x) load).

Fuel is a funny thing. It's the catalyst that allows for the combustion of O2 molecules. Along with charge density and air/fuel mixture, it determines the rate of deflagration (speed of the flame front). It can have a positive effect on pulling heat out of the chamber overall. It dictates when the spark plug can be fired and how strong that spark must be. It also dictates not only what kind of spark plugs must be used (in terms of heat range) but also what effective compression ratio can be used in the motor.

In terms of the use of a non-turbocharged motor like the stock 10:1 Renesis, of course a lower octane fuel will yield more power. One of the greatest misconceptions the unsuspecting public has is that 91-93 octane fuel, which is more expensive at the pump, is somehow more powerful and better to use in their grocery-getter, putter-putter cars. Infact, it's not, even though there may be certain additives and detergents added to that higher octane fuel that may lend towards longer engine life (depending on the manufacturer and vendor). Octane rating in a nutshell is an established measurement of an engine's resiliency to engine knock, be it pre-ignition or detonation, depending on the circumstance. The lower the octane rating, the more volatile and easily lit the fuel is. Lower octane fuel yields greater power per stroke (in the form of BTU's; heat energy). In the case of the Renesis N/A motor, like the older non-turbocharged 13B's preceeding it, a more volatile fuel is perfectly fine to use, will produce more power, and will cost alot less too. Boosted is a different story however in that not only will intake air temperatures (IAT's) be higher but also the load on the motor will be more severe in that the density of the charge is greater, requiring a more stable fuel due to the fact that once the denser charge fires, it will burn with more rapidity.

The things that determine a fuel's efficacy as a heat exchanger in a combustion chamber is its latent heat of evapouration (how much heat it draws when it flashes from a fluid to a gas) and its specific heat (how much heat it can "hold" prior to heating up itself. Lower octane fuels usually have lesser of both of these. Gasoline in general isn't high on the list at all. Infact, it's low and is comparatively-speaking a very poor heat exchanger. Alcohol fuels are the anti-thesis of all that is bad about using fuel as an anti-knock agent. Methyl and ethyl alcohol fuels are through the roof on latent heat. Water, although not a fuel, is amazing on the specific heat index. The main deterrant to knock for a fuel will be its auto-ignition temperature which is challenged in its fullest fury just prior to TDC (during the end of the compression stroke) and thereafter once the charge is fired and when both pressure and temperature rise. Gasoline fuels range from mid 400*F to mid-high 600*F. Alcohols are in the high 700*F's to low 800*F's.

Hope this helps elucidate some of this sometimes-complicated topic. On a side note, once you understand all of this, you'll also understand why E85 is such a bad idea for any heavily non-FI'd vehicle. ;)

B

How is fuel a catalyst that allows for combustion of O2 molecules?

Why is a low octane fuel more volatile than a high octane fuel?

How does lower octane generate more power per stroke?

How does this specific heat work?

why is E85 such a bad choice for non-heavily FI'ed vehicle, isn't it cheap?

Higher octane fuels take more energy to light and burn more slowly. Higher octane fuels are more stable and can therefore be used with higher loads or hotter environments. Higher octane fuels, all else remaining the same, produces less torque per stroke due to its lesser volatility.

http://en.wikipedia.org/wiki/Deflagration

It's a more volatile fuel. Takes less energy typically to light and start burning. It burns more quickly, so each punch of energy that's produced is stronger. It's more ferocious than a higher octane fuel. Think of it that way.

Try a peek at this:
http://hyperphysics.phy-astr.gsu.edu...ermo/spht.html

Gasoline fuel's specific heat sucks, IMO, where alcohol and water far excel. The reason why it's common for tuners to run such rich air/fuel ratios while under boost (for example: 12psi of boost running 11.5:1 AFR) is because the extra fuel in the charge, making the chamber awash, is used as a heat exchanger to pull heat out of the chamber that's being created because of running boost (high loads) in the first place.

Per volume, it produces nowhere near the amount of power per stroke that straight gasoline does. It might be cheap, but you need alot more of it per stroke to make the same power. Ever wonder why you need more (and/or larger) fuel injectors and pump on the back-end for it? E85 is 85% ethyl alcohol (ethanol) and 15% gasoline (not sure what octane or kind). E85 takes more energy to produce than what it outputs. It's also a drain on the economy in that it's made primarily from corn which raises the cost of most other food but that's a different discussion altogether. Don't get me wrong; I think it's great for a very boosted setup simply because it's almost all alcohol. I just don't think it's practical for your every-day, daily driver car that's not like what we're doing.

B

Hey Brian....how's the Alky Control thread going...missed your updates :)

I wish I were able to load-tune the car but I can't because the clutch is finally starting to slip. I've got an ACT un-sprung 6-puck disc that I bought and installed in August of '99. I've had it in there for over 8 years and it's finally starting to see sunset. I can't load the car out past about 9-10psi of boost because it begins to slip off. Oh well. I'll replace the disc soon (got a good deal) and get back to load tuning. I hope to break 500 to the wheels with this new turbo and methanol.

B

I really love Wikipedia, Ray. http://en.wikipedia.org/wiki/Combustion

I hope I'm not ruining this thread. :(

B

Sounds like a good X-mas day project :lol: I told my wife that what I wanted for Christmas was NO hassles about putting the engine back in my car before dinner:)

Brian - I applaud you for answering this stuff.
I didn't have it in me to do it again.
And again.
And again.

I think this is a sticky somewhere, isn't it? Oh, that's right:
https://www.rx8club.com/series-i-aftermarket-performance-modifications-23/so-you-wanna-tuner-100333/