Federighi

iTrader: (7)

I'm very surprised that 8 was able to keep up with the MPS / Speed3 on track (which looked like a street car with light mods imo). I will say that from my experience, the Speed3 is rather difficult to drive 'spiritedly' due to its' prevalent torque steer and heavy near 3300lb curb weight from the factory. I found the factory inputs too soft for my tastes but the triple solid motor / trans mounts in 80 durometer along with some other practical suspension mods really changed the character of the vehicle for the best; given you can handle some NVH.

By comparison, I say the Speed3 is like a hammer where the 8 is the scalpel. Driving the 8 is effortless and I'm very much looking forward to getting both my cars on a dual track day but I'm pretty sure the 8 has no chance until I get the G30 going.

TeamRX8

iTrader: (25)

well again there are variables/assumptions in those observations, which is why I’m focusing on indicated speed vs time and speed relative to non-moving objects and points. And on the straights or near straights, not from turn in to exit through the turns.

Because as I stated earlier, if you go watch vids in the race/track forum area there are plenty of faster RX8s on here. Member dallasreed’s RX8 is way, way faster, but I know he has a lot of weight removal mods. Aero too, so obviously he’s way faster not just on the straights but through the turns as well, but he also has to accelerate against that aero loading from corner exit to corner entry i.e. the straight sections. There are other less modified RX8s on here that appear faster imo too, but they do have some weight removal and how they compare in total car+occupant weight of this car is the one thing I’m not sure of that could be impacting my observations.

I suppose I’m not really surprised about the different perspectives though.
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Federighi

iTrader: (7)

The 8 appears to be well sorted and I agree there are many variables present but imo, any 'prepped' track car (whether owned or sponsored by a team) shouldn't have any problem dismissing a common street car. Maybe this was just a poor showing? Not sure, but certainly not a great representation of their work / driving / the platform imo. All cars have the potential to be 'fast' when driven properly. I'm not sure what the gripe is here other than a bruised rx8 ego.

And I think some praise might be in order for the Speed3 driver, no? The Speed3 is a juggernaut and not to be underestimated. The car is infinitely more difficult to drive fast and the driver did a reasonable job doing so. I've had the pleasure of driving my local tracks which sometimes host practice days for national clubs and my particular Speed fits in real well with the ST4 guys. Speed's do require a lot of work to be track friendly / worthy but it is nice being able to load up and drive away at the end of a long day.

TeamRX8

iTrader: (25)

that’s as expected, seeing as how most everybody except Brettus fails to recognize why it doesn’t measure up to a stock port Renesis

I don’t bruise so easy; next time try sticks and stones rather than nerf *****.

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Federighi

iTrader: (7)

Ha! Nerf *****! It wasn't directed at you Team, I know you don't chafe easily. I love my little rx8 too

Not to beat a dead horse, but entry speed / track line / brake zone are not lost in my observations and imo, comparing what I'd assume was a sub -2700lb 'race car' to a +3200lb 'street car' is a very, very unfair matchup. Race cars are meant to be light (like 2200lbs light) and heavy cars are less than ideal for track performance (I know you know this); physics and all that. Also worth mentioning that FF vs FR cars have very different driving styles (duh) and generally take different lines on track. I'd personally like to know what tires they both were driving because that's one of the most important variables to consider when making unfair comparisons like this. Is this info known / shared somewhere? The Speed is thoroughly outclassed in this particular environment and I still say did quite well for itself. Although I ultimately suppose it boils down to how one value's 'different characteristics of a vehicle's performance' on track and therefore, makes different evaluations. And imo, anything beyond 'having a good time' on track is an ego trip imo.

Not to mention the MZR consumed what I'd estimate was half the amount of fuel the rotary did over the course of the day.

blackmount

Something to keep in mind, turbo cars, especially factory turbo cars, and poorly setup aftermarket turbo cars like every Turbo Renesis build ever, and majority of Turbo Rotary builds in general, often with massive, but heavily inefficient intercooler setups Will lose 20% of their power or more after 1-2 laps around your average race track, especially a track like Sepang where in the dead of night it's still 70-90*F. Assuming they are actually tuned well, and will adjust to the heat, rather then just grenade... So chances are that MazdaSpeed 3 was already down on power quite a bit from the heat...

Significant Power Loss due to Heat is always a battle on a forced induction car, even when talking full fledged racecars with massive development budgets, and thousands of hours in testing, which is one of the biggest advantages to a Naturally Aspirated engine, besides also being significantly less in weight...

Brettus

iTrader: (2)

On a hot (over 30c day) maybe. Not so much in moderate climates though.
I'm on my 4th or 5th IC iteration and gone from it being pretty hopeless to honestly say it's very efficient now.

blackmount

Give it to me and let me torture it on the dyno, I bet i can make it lose more then 20% power...or just cause it to blow it up..... probably the latter given its a turbo Renesis.... Every keyboard warrior thinks their cars cooling is sufficient enough until it actually gets pushed beyond a single 3rd or 4th gear pull.

Ricky SE3P

iTrader: (10)

uhh.... Brettus doesnt only dyno his 8, he tracks his 8 and logs it.. sounds like youre the keyboard warrior

blackmount

And it sounds like you can't read....

Brettus

iTrader: (2)

Dyno is not the track ...no matter how big your fandango is, you'll always get better cooling on the road than the dyno.

blackmount

Right to an extent, its hard to throw drastic altitude, and massive temperature changes into the mix on the dyno I agree with that... but 99% of people with any sort of controversial setup talk a big game but never actually push their setup to the limit to see when it will actually break on the street.... They will never try to see how the car handles back to back Zero to Reasonable Top Speed pulls in -30*F Temps, and then again in 110*F Temps, or run it up a mountain like Pikes Peak.


Usually someone pushing their car, especially the people always putting 110% of their effort on peak horse power numbers, instead of real world usable horsepower, is just rowing 1st-3rd down an onramp and logging it, then manipulating the numbers in VD and bragging on the forums about how much power their car made, while it makes 60% less power then a stock version across 80% of its Power band.

Slawekn1

It would be foolish to compare a dyno session with compromised airflow to a track session. I run a turbo Miata NA that is notorious for heat issues above 250WHP on track and all my heat issues basically disappeared with e85 conversion. I can run a steady 185 Coolant and 190F oil for 30 minutes of a track session in 95F ambient.

TeamRX8

iTrader: (25)

I keep waiting for California to slide off into the Pacific Ocean the way this thread slid off into a deep sea of silly, off-topic nonsense …
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Jose Zuma

Whether it performs better or not, in my opinion having a peripheral exhaust port will help to reduce the port temperatures during track time. I doubt the side exhaust will do/last better.
Also, that car measured 220whp in a Mustang dyno, Mustangs usually read a lower than other ones (depends of many factors). This figure seems good to me.

TeamRX8

iTrader: (25)

except as commented on youboob, Renesis engines don’t last long at higher revs

and also going to take exception to the exhaust temperature comment; the peri exhaust has traditionally run hotter than the side port exhaust. Note the the peri exhaust port opens sooner than the Renesis side ports, so the combustion is still burning strong when it flows out the port.

and finally, my 220 whp Mustang dyno graph from 2008 is posted on the forum, and that was the original factory Mazda Renesis engine as a pre-production beta tester for the Cobb AP. There is no benefit to this engine over a Renesis that can make more torque and power at lower peak rpm points.

yet again, as expected …
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Jose Zuma

I haven't seen any housing shrinking close to the exhaust port as the Renesis does in the iron around the exhaust port area, not to mention the coolant seals getting toasted in that area. Temperature-wise you might be right, I formulated a wrong point.

Powerwise it might be similar, so similar to prove that the added overlap doesn't seem to be affecting the power output of the build. While on a N/A this makes less sense (except for being more reliable during track times), with a forced induction engine the heat gets worse and the iron is even more prone to shrink. Not the mention, the extra exhaust helps the engine to flow better.

TeamRX8

iTrader: (25)

in comparison to what though?

I’m not aware of you posting up any results for an assessment against the alternatives.
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Jose Zuma

The guy who did the track video that you are talking about posted the dyno result: I mentioned the numbers earlier.

Now, the stock renesis in a mustang dyno, that's your call. Although, it will be more useful to compare apples to apples, a Bridgeport Renesis vs the Bridgeport Hybrid Rene of that guy.
Choosing a stock renesis dyno result to show how more low end power it makes in comparison with a bridgeported it makes no sense👀 .
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peloponisios

It makes some sense when the stock port can make the same top end power with this hybrid bp iteration, as stated many times.

TeamRX8

iTrader: (25)

Just confused by your commentary; thought you were referring to your own turbo project. First, you’re the person who opted to bring “Mustang dyno result” into it. So don’t pin that on me. If you’re referring to that particular engine, how did you acquire the data to reach those previous conclusions? Because your comment cleary is phrased as direct, intimate knowledge of the data.

I’m not really surprised that you can’t see why that’s all wrong on multiple levels though. It essentially makes less whp and tq than what a stock port Renesis is capable of achieving at lower peak rpm points. This hybrid engine just happens to carry enough of that lower tq output to a higher rpm to achieve what it did is all. That’s not only less performance without a true benefit, it’s going to result in lower performance sooner once the the accelerated wear takes it’s toll.

There are some very good reasons a stock port NA Renesis achieves what it does compared to other NA 13B engines. All that happened here is the peak hp shift point is moved to a higher rpm, but at the expense of lower overall performance to get there. Based on my Renesis knowledge and experience, I’m confident engine life/durability is going to be compromised by it.

In the end it didn’t generate enough performance in the higher rpm range to offset what it lost in comparison to what a stock port Renesis can achieve. That’s not what a strong 13B BP engine does, just the opposite. My position has always been that the extra costs involved won’t provide the results to justify itself.

As much as you might wish in your heart that it did, this result doesn’t disprove that. This was not a cheap build in any respect and the result has come up short.
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Brettus

iTrader: (2)

At least you now acknowledge that it is making more up top .....
Looking at the dyno , it looks at least on par with a good stock port from 5000 on up . So yeah ...it will be quicker than a stock port on track, no question ...just not by much.

TeamRX8

iTrader: (25)

No, it absolutely doesn’t match the best stock port Renesis engines. That’s maybe just the perspective of someone who never had one, or saw one, or forgot.

What I acknowledged is that it still makes less tq and whp than the strongest stock port Renesis engines, with a loss in overall performance, and the tq and hp peaks shifted higher. It’s a lose-lose to anyone who understands how to assess it properly.

As stated in the copied reply; it shifted performance higher, but without sufficient gains to offset the losses required to get there. It’s really not any different than hogging out the intake manifold and losing more everywhere else than where it ends up at. Which I’ve repeatedly warned on the forum about not doing that.

I really don’t get what people don’t understand about it has less power than a strong stock port Renesis does at a lower rpm. 220whp at 9200 rpm does not trump even the same number at low-mid 8000 rpm, let alone a higher output there. Because it took a higher torque value to achieve it at a lower rpm. Once it crosses over the 5250 rpm point and higher, that matters. That’s what everybody wooting this up seems to be missing. On top of that, it costs more to go this route too.

This hybrid engine needs a lot more than it has just to keep up, which it won’t keep up.
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Jose Zuma

Same as a stock port usually makes more power than Renesis BP.... If you want to compare stock port, then compare it with a stock port, too many variables when porting an engine...

Jose Zuma

Choosing one of the best stock port dyno sheets (out of many in this forum which doesn't even pass 200whp) isn't fair when you can only choose 1 hybrid renesis dyno sheet out of one. It's easy to pick up the best result when you have a lot of data. As stated earlier, porting can go wrong or good in a hybrid as in a Renesis. If you want to really compare both then do it under the same circumstances! Otherwise its pointless.

Build price, I don't know where do you live Team... At least where I live a GSL housing is way cheaper than RX8 housing. The only extra cost will be the exhaust manifold and machining the rotors. Now, in my opinion this setup makes no sense in a street car that doesn't see the track or it isn't turbocharged. A stock Renesis is great as a street na engine, hands down.