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yet people on here want to discount the guy with a stellar 40 year rotary engine motorsport background who was hired by and built special projects for Mazda including use of the Renesis engine, and easily can bury anyone elses claim to Renesis engine/dyno experience.
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Not at all . I'm sure he builds a great engine . I'm not so sure he makes 30whp more than other good engine builders though
And what you have shown us so far doesn't prove that he does ...not in my mind anyway.
In this case peak torque that it showing is actually the tip in blip at the start of the run. So they didn't make 90 more torque. But it looks just about 25kgm or 180lbft.
It looks like they were doing this in 5th btw, if using stock gears and final drive.
[edit] counting the dots it looks closer to 20kgm, so 144lbft? So at 5252 rpm torque = horsepower on any engine. Around there they have about a 7-10hp gain, so logically torque should be higher as well. So either 144 is the original torque and they didn't care to plot the new one (would be weird) or the new torque is 144 and it was worse before. Or they completely goofed their dyno ratios and none of this means anything.
In this case peak torque that it showing is actually the tip in blip at the start of the run. So they didn't make 90 more torque. But it looks just about 25kgm or 180lbft.
It looks like they were doing this in 5th btw, if using stock gears and final drive.
[edit] counting the dots it looks closer to 20kgm, so 144lbft? So at 5252 rpm torque = horsepower on any engine. Around there they have about a 7-10hp gain, so logically torque should be higher as well. So either 144 is the original torque and they didn't care to plot the new one (would be weird) or the new torque is 144 and it was worse before. Or they completely goofed their dyno ratios and none of this means anything.
(Edit): "Peak torque at initial blip" ... Ah, I see that now. Just looked at peak #s initially. Well, as it stands.. not quite as impressive. Juice seems only worth the squeeze in specific cases. 🤔... 😂
One not insignificant detail, its using the OEM cat.
i do beleive they got 30 to 40whp over stock. An RX-8 with the same engine is running on time attack and posting near identical times to tuned S2000s so the power is there considering the rx-8 is heavier than the S2000.
They clearly know their stuff.
there are many variables why one car may be equal or faster than another on a track, Id be more interested in seeing a 1/4 mile trap speed near sea level with total weight as a more effective measure of hp
they have a higher flowing S OE cat converter option in Japan. Which 220 whp on an unported engine with high flowing cat is not so uncommon
I actually said the opposite; the same max output results have been claimed in Japan; 270-280 PS, just that I never saw anything to back it up. Which also again, the numbers are backed up over way more engines and dynos than everything on this forum combined; all the Renesis engines for the Pro Formula Mazda race series up until 2013. Theyre all spec engines, blueprinted and balanced, broken in and verified on a Superflow engine dyno.
Its also with an open exhaust, which is always going to produce the best results. That was the other thing that had me question their results, which again the way the engine sounds and accelerates doesnt jive with my own experience. It seems more like a decent street RX8.
The baseline is an issue for me too. Its like claiming the usual 175 - 185 whp most street RX8s pull on here is a baseline. A used engine of unknown condition and OE tune is not a proper baseline against a new hand built engine tuned with mods. It will definitely make an impression if youre trying to merchandise the situation though.
but if somebody can reproduce what theyre doing and post impressive results, Im open to seeing that. To me its not any different that whats transpired here for the last 17 years. Theres no shortage of claims of everything under the sun.
I don't see where you got this "S" cat thing in Japan. I have mine, which I took out, looks exactly the same as all the catalyzers i've seen here on pictures. I doubt Mazda would go to the trouble of making a JDM specific cat, remember this was a 32.000 usd car in Japan when new. Different tune, maybe, but that is way more cost effective.
Also, unless you are in direct contact with actual owners from RX-8s here in Japan, I haven't seen anything on your posts that supports all your theories.
I've seen a few dyno posts here in Japan, most with oem tune are between 170 to 180 whp (metric PS) actually, a tuned one with a header 190 something, same dyno (as it is the most popular here in Japan). They all run cat's, most OEM (this is one of the cheapest used sports cars here so people don't really see the point on spending 1/3rd of the car's used price on a sports cat).
As for trap speeds, in Suzuka, this RX-8 runs about 2min21s an S2000 might run 2min20 in the same state of tune. This is a high speed circuit.
By the way, people are not really into HP wars, more into handling or grip as they call it, they don't go around posting what HP they got or whatever, their real measure is lap times on time attack.
Also, the amemiya porting seems to be mostly on the auxiliary ports, extending their timing, where air velocity is highest at high rpms.
260ps crank with all these mods and cat seem completely possible to me. This guy with a high flow sports cat got 270ps on the same tune, I saw the graph, well actually, here is the link. Use google chrome to have the page translated. I know him, ran on the circuit with him, have seen his car. GWOH̃p[`FbN&ZbeBOGCgIRX-8(GCg)͐EBBBiGCgARX-8 blog)
because I can order it and a variety of other higher performance JDM RX8 “S” parts through Mazda Motorsports here in America. However, I only see it in the parts list and it says higher flow. That may be relative to the US spec cat. I never bought one and can’t really say. So it might just be the standard JDM part and my conclusion was wrong in that sense.
I think what you’re missing is that 270 BHP is possible on stock ports. When they first started building them in 2005 it was only 250 BHP. Then progressively build that up over time through various tips and mistakes learned over the years. A lot of the porting things that came out over the years were already done and tried long before anyone here ever saw them. They never saw more than 10 BHP modifying the ports and the determination was the exhaust port was the limiting factor.
The only way to get more air in is to get more air out. So no matter how much you hog out the intake, the exhaust port is going to limit what can be done. The limitations were discussed and illustrated earlier in the thread. Due to the water jacket positioning and the eccentricity limitation of the seal paths, it’s simply not possible to get any big improvement out of the exhaust ports. What amount you can get will impact side seal life and limit how long the engine will operate there before losing what was gained and more.
A good example is the Renesis bridgeport nonsense. When I showed and discussed that, the comment was it was too small to benefit flow much, but it wouldn’t really matter much due to the exhaust port limitation. In essence, all it really does is introduce exhaust gases early into the intake ports resulting in lost power. Of course this isn’t what they’re doing in that porting exercise, I just point it out as people trying to apply past 13B techniques to a Renesis without fully understanding the difference between the two. Yet they all swore all the brapping meant more power. Nope.
The same shop builds true 13B & 20B race motors and is familiar with all that stuff. I have some pics of their 350hp 13B PP engine somewhere. The same 20B is 480+ hp. I realize other shops in the world can do that too. It’s not just some guy talking crap in his home garage and never proving anything is all.
Just read your edit because you pointed it to me, thanks, would have missed it otherwise. I have to view again a best motoring video testing the Mazdaspeed RX-8, they list the modifications. When I went to the dealer to install the second oil cooler here, I had a look at their motorsports catalogue, they had a bigger radiator and a high flow cat as options, but I think it was an aftermarket one, I know you can have dealer installed Autoexe parts at Mazda dealers here as an option so it might be that one or something.
As for the engine building, I can only talk about what i've seen, but given the amount of engines around the world, i'm sure amemiya and other local tuners in Japan are not the only ones to have achieved it. On the porting, I agree with you that bridge ports are useless on the renesis, if you look at their porting in the video, they seemed to have maximized what they can do with the exhaust ports and the intake porting done was to have the auxiliary ports open for longer, probably looking to achieve a higher VE at high rpms. It's definetely not just the porting but a combination of parts for sure, plus proper seal clearance, still that power over what you usually see stock on a healthy compression engine here is pretty good.
part of the issue is we have no understanding of the numerical value being applied between WHP and PS. If you assume that there’s a 15% drivetrain loss then this dyno equates to 267 BHP = 271 PS
2020
We have several strong engine dynos on here that you can then apply the same percentage to (BHP x 0.85), but it assumes that the tune is equal between what was used on the engine dyno vs in the vehicle pcm
Yes, you have to change those to metric, PS, really good numbers, the engine dynos I assume are with no anciliaries? The one with the 226 whp, any details on the setup? Just trying to compare apples to apples.
It was E85, those other Superflow engine dynos are all Drummond builds, 100 octane race gas. All stock port. Engine dynos are Motec pcm, same as used on the Formula Mazda cars with OE coils, open exhaust, cold race plugs, increased oil pressure, blueprinted & balanced to within 0.0002 oz-inches, pretty much most things are OE otherwise. Think the first one is Adaptronic modular. You can get pretty much close to the same out of a tuned Mazda pcm, except there are certain conditions; at least for USDM pcms, that can cut back power and create some other difficulties. That’s the main reason to use an aftermarket pcm, and a few other minor strategies. The Pro Formula engines run the Motorsport dry sump front cover/system too with premix.
The other longstanding myth on here is that the engine runs better on low octane fuel; maybe on a low compression Renesis, but not on a good sealing one fully tuned. Ideally you want to machine the rotors for deeper RX7 apex seals and run Iannetti ceramic version for the best best long term wear and sealing on the rotor housings and rotors, but some racing classes don’t allow for that. Or porting either, but I don’t fret over anyone doing it because they’re likely causing more harm than good going there. Trying to port the LIM can also screw up things real fast too. Just smoothing rough spots & polishing is all that should be done.
The shapes & volumes in the intake flow paths are fairly critical. Even on my modified UIM where I removed the 22 deg bend at the throttle body so it points straight forward to the front air inlet opening, I was careful to maintain the same ID and same tract length. All the resonance tuning occurs in the intake, the exhaust has none due to zero-overlap. Even if it had overlap and relocated intake ports, the split exhaust ports and siamese port configuration are going to dilute pulse strength and make negligible any attempt to resonance tune the exhaust. People still argue over that though even with no overlap due to lacking a full understanding of the dynamics involved.
I see, I see some differences on the setup that would explain some of the differences, here high octane fuel is 99.8 RON minimum, most over 100 octane though. It seems their porting makes up for the restrictions on a road system.
I see, I see some differences on the setup that would explain some of the differences, here high octane fuel is 99.8 RON minimum, most over 100 octane though. It seems their porting makes up for the restrictions on a road system.
It’s not a significant difference; it’s (RON + MON)/2 here.
Addressing the specific comment though; perhaps you should ask yourself how that’s possible given the limitations discussion? I’m not saying they didn’t gain anything, but what did they really gain over a stock port engine otherwise freshly built & tuned identically to the modified port engine?
That’s what the max 10 BHP figure was determined against. What’s at question is the magnitude and how relative it is. We’re talking about a shop that has many of that kind of baseline engine build to compare their porting experience directly against. A shop that’s intimately familiar with every rotary porting technique and port type likely to have ever been used.
Because the exhaust port is limited by the inner/outer seal paths and water jacket before it will result in overlap/bleed exhaust gas into the early-opening intake tracts. Which even the final port shown doesn’t match the artistic attempt penned in at the start. I suspect they threw more than the one iron plate away that was shown in the video. I’m also betting they had a few new builds that were duds too for the reasons stated.
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Its not a significant difference; its (RON + MON)/2 here.
Addressing the specific comment though; perhaps you should ask yourself how thats possible given the limitations discussion? Im not saying they didnt gain anything, but what did they really gain over a stock port engine otherwise freshly built & tuned identically to the modified port engine?
Thats what the max 10 BHP figure was determined against. Whats at question is the magnitude and how relative it is. Were talking about a shop that has many of that kind of baseline engine build to compare their porting experience directly against. A shop thats intimately familiar with every rotary porting technique and port type likely to have ever been used.
Because the exhaust port is limited by the inner/outer seal paths and water jacket before it will result in overlap/bleed exhaust gas into the early-opening intake tracts. Which even the final port shown doesnt match the artistic attempt penned in at the start. I suspect they threw more than the one iron plate away that was shown in the video. Im also betting they had a few new builds that were duds too for the reasons stated.
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With the way those ports looked, and the amount of timing that appears to be added to both intake and exhaust, I am surprised they did not lose a lot of power, that would bee seen on the dyno trace.
Also, on my stock tune rx8, I have never seen a knock event running 87 octane fuel, even while testing for this in 115 degree weather. It does not have low compression. With a real tune, then yes, maybe so, but the difference in how the car performs on 87 vs 91 octane is very noticeable. We all shouldn't just torpedo that notion for this car in my opinion. Also, there are many accounts of rotary racers in a series with a fixed fuel type adding premix (alot) to drastically lower octane to get a quicker burn and more power on the track. This goes back many years. Granted, the Renesis is different, and the dynamic compression ratio is also likely higher than the difference in the static compression ratio would indicate vs earlier rotaries, but again, a stock car can run 87 in my opinion without issue, and the car seems to run better on it. I believe Mazda's recommendation for premium fuel had more to do with detergency and burn quality than with octane. (Tier1,etc)
Comparing performance on high octane pump gas vs high octane race gas is not direct. Most racing fuel that I am familiar with adds power everywhere, in just about any engine type, regardless of the octane needs of the engine in question. So comparing low octane pump gas, high octane pump gas, and high octane race gas, is not an A-B comparison, but rather an A-B-C comparison.
except RE-A focused on the area away from the water jacket and doing it by hand that way is more effective. CNC provides consistency, but at the expense of max benefit because it has to account for casting tolerances and variances.
Most people never knew that all this was done a long time ago, way before these and other people posted it up. You’ll never get that from Mazda though, due to it creating much dirtier exhaust emissions. You can see how limited it is too; about 10 BHP is the max peak benefit.
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you know I’m your brother in Christ and won’t deny you of anything, but especially the truth as I understand it.
A similar response was made earlier on this subject and my tongue held back, but your insistence to only hear and see what you want to believe based on a false premise cannot continue to go unanswered. Your response lacks any validity. To glory in it is to only compound upon and increase the error thereof.
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you know Im your brother in Christ and wont deny you of anything, but especially the truth as I understand it.
A similar response was made earlier on this subject and my tongue held back, but your insistence to only hear and see what you want to believe based on a false premise cannot continue to go unanswered. Your response lacks any validity. To glory in it is to only compound upon and increase the error thereof.
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Well,
I think if I explain further, we will find we agree more than we disagree. I am not sure you understand my position based on your response.
I was surprised by the increase in intake port duration used in the REA example did not upset the 13bmsp intake tuning more, and the engine making much less power than stock. I believe that a stock port engine would make similar power to this one,(maybe more) when tuned the same/ and same bolt-ons . And, the peak HP increase, if any, would not be worth the lower torque elsewhere.
When I used to port 2 strokes, (or try) a highly factory developed cylinder would get a very light touch. The very last thing I would try on such a cylinder was modifying port timing. Most of the time there was no gain to be had, and usually any change at all resulted in an instant loss. Almost the same with 4 stroke heads. Too much intake port volume and you would have what I called an "air-bog motor" where the intake port was too big for good velocity at mid rpm, and only had good cylinder filling at very high rpm, when intake velocity was high enough to offset the damage you did to the port. I recall some engines were even a bit like this from the factory, when manufacturers were in a HP war. The engines I ported incorrectly were failures, as the peak HP number was good, but torque was actually down over stock until the final 1000 rpm or so. So, a slower car or bike resulted. I have ported somewhere close to 30 different engines over my lifetime, but many more if counting the same engine multiple times. Some of the "porting" jobs, as I got wiser, were almost nothing. Like the Renesis is in my opinion.
Also, I get what you are saying about the sound of the REA engine. It sounds off, kind of like an "air-bog" motor to me. Its not "crisp" . With intake port timing that radical, I would be led to believe the oscillating pulses and air columns in the manifold are both mis-timed and softened. So, the manifold will not work properly, resulting in loss throughout the rpm range until high rpm.
11-18-2020, 10:22 PM
