The One RX-8

Well I'm glad to hear the rating is down by Mazda because it wasn't pretty. On 91 octane, California gas.



and



Next time I'll try 100 octane.

revhappy

That equals from 202 - 209 Crank HP assuming a 17% drivetrain loss. Using Mazda's figure of 238 HP that would be about a 27%-30% drivetrain loss. The difference between this and many of the others (done at 93 octane I think) is about 5- 10 WHP, which seems to make sense.

There is no way this engine is spitting 238 HP at the flywheel or that carbon fiber drivetrain was one big waste of money!! These numbers all seem to be consistent with my view that the RX8 felt about as fast, if not a bit slower than the RSX Type S and Celica GTS.

Lensman

That's horrendous!
Can we assume that Mazda's 238bhp announcement is simply a diversionary tactic to stall the outcry and perhaps head it off. Perhaps the forum should put as much effort into pushing for an answer to the 'where is the stated 238bhp' question as it did for the 'where is the stated 247bhp' question. Something is VERY wrong here.

jerzeydevil

Granted I haven't been reading the other threads on this topic in depth and don't claim to be an auto mechanic in anyway, but according to these graphs and others I've seen....isn't it a bit suspicious that when the 3rd intake opens nothing much happens except that you lose power for a second? Their is no significant gain from only 2 inlet ports.

I would expect this graph to continue on upward to the annouced HP numbers (- drivetrain loss) from Mazda once that 3rd port opened....wasn't that the point of it? This falls right in line with what some people are experiencing with the lack of (expetected) punch above 6500rpm and/or the inability to rev easily past that point...this is clearly visible on this graph.

revhappy

I guess the Renesis will not outdo the F20C in terms of linear torque curves? BTW..did the International Engine of the Year award only consider new engines because I can't see how they could have picked it over the F20C, given the Renesis's current performance.

Kuf

Is that an AT or MT?

TinkySD

What's up guys. I'm actually a TSX owner and admin at acura-tsx.com and have been following the the RX8 and this interesting HP saga. I know a lot of you have very poor impressions of the TSX power plant and car in general. I'm not being a troll but wanted to post this tsx dyno as a comparison as I know a lot of you have very poor impressions of it.




This is one of our users with the 6mt on a dyno jet, about 1500 miles on his car. Honda seemed to underate this motor, it's more like 205 hp or so and 180lbft.(we have another dyno showing 179hp but it's from a mag so I dont' know how believable it is)

revhappy

It looks like another great Honda powerplant.

RX-Nut

Looking the same........ how many miles on each car?

TinkySD

Honda seems to have made a bit of a compromise on performance with this engine. They gave it a lot of low end(relatively) at the expense of some top end hp. So far it seems to respond well to mods. Anyway like i said i don't want to hijack or be a troll. Just for comparison purposes. The car is heavier +fwd so it's not going to be as quick. We have one user all sock hit 15.5 @90.xxmph. (stock tsx tires are touring allseason)

rotarynews.com

Actually, next time try 87 octane on one...

rx8racer

Trying a lower octane may help. It seems to give my car a couple extra horsepower and more importantly it seems to lessen the dips during the intake port switching. I posted some "dyno" tests here:
https://www.rx8club.com/series-i-tech-garage-22/more-g-tech-dyno-results-9402/

What was the temperature during the dyno runs? Even when I am running 93 octane, my car seems to dislike the heat. On a very hot day my car will lose over 10WHP due to the weather. I imagine it would be even worse on a dyno without air circulation of the car in motion. I'm waiting for a nice 50 degree night to do a cold weather test.

zoom44

thanks Dan as i was questioning the same thing. The One RX-8, what exactly makes you think 100 octane would help here? you dont seem to understand the differences between octanes.

TinkySD

How eactly does octane work with rotary motors?

It's a trueism that lower octane fuel is less refined and thus has more potential power in it. With a piston motor what higher octane does is require a highe rcompression to be ignited. this lets you adjust ignition timing for more gain, but not because the fuel itself has more energy in it.

The One RX-8

Both cars had around 1500 miles. Both were 6MT's.

No temp data while on the dyno. I know while driving underhood temps have reached the 170F near the the throttle body. Where the air is drawn from however is close to ambient, right under 90 degrees. I couldn't get the IAT's due to the CAN system that Mazda/Ford uses.

I will try 87 octane as well.

The One RX-8

I am testing on claims only. 95 is the recommended octane. 100 octane is my next closest choice.

The One RX-8

Outside temps are noted on the dynograph. The first car was run in the afternoon and the other at 8 am. These cars seem to have one of the most heat generating engine bays that I've worked with.

brownchiro

Do you think we should be using 87 octane. This is my first rotary and I have been using the Premium. 15-19 mpg. Thanks

rx8racer

I noticed that the charts seemed a little wavy after the 7200 rpm dip. This may have been the ECU backing off the timing due to detonation in the heat. I'm just taking a guess but it would explain the low numbers in the heat. I'm going to try my car on some 87 octane in the 85 degree heat in about an hour today. We'll see what it does.

TinkySD

if you are getting detonation isn't higher octane the way to go? Or is that a difference in piston vs. rotary. Intuitively does't seem so as higher octane requires higher heat/pressure to combust.

Quick_lude

Damn those numbers are low.. My Prelude dyno'ed around 168whp with a few basic mods..

At around 7400rpms the hp/tq take a big dip and never seem to recover after that.

NashuaCLS

Exactly my thought!, A Car Mag complained that the third stage intake ports are stuck and thus there was a loss of power. Mazda found out that this is the case, and instead of recalling all engines, it just gave out rebate/buy back deals... That totally sucks!!

I would expect the Torque curve to stay above 125 lbft all the way to redline. It seem that the 3rd stage is not working.

We saw a drop of 25 WHP on the Acura CL-S when the 2nd stage intake valave was faulty !!

Nashua.

zoom44

it was SCC on a pre-production car before any production cars even in japan were on the road. the stuck port was found to be a manufacturing problem from the parts supplier and was fixed before production. there have been no reports of any stuck tertiary ports in any production car in Japan or the US.

1stRX8

After all the HP saga, all the guessing and speculation. Mazda's admittance of lower than stated power, etc, etc. I dynoed my car at 1050 miles 5 weeks ago and averaged 180whp... bla, bla, bla..

Today, I got spanked [actually about even] by a Toyota Solara V6 AT. It's 225hp and 3241lbs. Without any technical explainations - the RX-8 should NOT trail behind a Solara!!!! It's 13hp less and 241lbs heavier with an auto tranny.

Yes, the RX-8 is fun but it's NOT fast. Zippy. Weee. Where is the Zoom Zoom?

Mazda is LYING about the 9hp. It's WAY more than that. A $21,000 family car can pull on my $30+k "sporty" car.

FYI: Mine is a 6MT with 2700 miles, only me in the car and a half tank of gas.

NashuaCLS

That sucks big time. I just came from short test drive of the RX-8 6-speed. At 180 WHP SAE that is some 210 HP at the crank give or take couple HPs. That is a loss of 40 HP from that 247-250 HP claim. Mazda should Supercharged all RX-8 to get to 250 HP or 210 WHP! That is a 25 lbft at the wheels and 30 WHP lost...!!

My CLS will do 14.6s in the 1/4 in the 90F 85%Humidity summer heat. My CLS is so heavy like... at 3495 with me at 185lbs. I dynoed at 238 WHP Acutual and 226 SAE WHP.

I believe if the RX can lay down 135 lbft and 210 WHP at 8500 rpms it should hit low 14s and hi 13s...

Ah... Mazda is scewing us all.

Nashua.

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