Hello all RX-8 lovers! I'm new to this forum but have 100 posts on the RX-7 club. I own a 2004 RX-8 here in Sweden and have done some small improvements on it on a SUN rolling road with the latest software. Last year in November i dyno it baseline with Swedish oil company OK 95 octane unleaded result 217,2 hp@8800 rpm torque 192,2 Nm@6440 rpm. The rear wheel hp was 146 and drag loss 57 hp. I was pretty dissapointed with this result so i change the fuel to Shell V-Power 99 unleaded. This fuel is a co operation with Shell and Ferrari! It burns really fast which should give results to the rotary engine and it did! 231,6 hp@8990 rpmwheel hp 162,4. Torque now 195,7Nm@6490 rpm what a difference Since then i have added a 1-cell race kat and a 2.5" middle silencer and i pick up only 3,5 hp. Ihave tested it with a G-Tech Pro and recorded a 0-62 mph of 6,82s- 104m. 1/4 mile is 14,82s-95,2 mph. I will write here more about my modifications to the Renesis engine.

/Lasse

 

you have a higher octane fuel that is burning faster??? that is contrary to how octane works.

and a 2.5" mide pipe is going to do almost nothing as you have found..


beers

 

<= Noob guess

Perhaps he was getting better compression and thus getting more hp?

 

Oh really....

 

Easy guys. There could be a translation problem here.

Lasse,

Thanks for your data and welcome to the forum. Did you "dyno" these fuels a year apart? Was the first with a real dyno and the second with a g-tech pro?

-Mr. Wigggles

 

Thanks for the inputs guys! I dynoed the same day with OK 95 unleaded and Shell V-Power 99 octane unleaded. The V-power gained 14 hp over OK 95 octane fuel. Yesterday i dynoed again, same dyno same dyno operator. This time i had mount a OBX Racing header (bought from E-bay) on my car. Result -minus! 5 hp @9100 rpm! Quite dissapointing. Unfortanately i can,t compare the power and torque under 9100 rpm until next week. Second and last test for the day was a mix of 70% Shell fuel and 30% of Statoil E-85 that is 85% Ethanol and 15 % gasoline. What about this:+plus 9 hp@9200 rpm! Lambda went from0.81 to 0.89 a nice lean out situation. That make my day!! My goal is 250 hp dynoed hp with out mapping.

/Lasse

 

I have a hard time with this test. First we don't know the correction factors or if there were any. Next the numbers in Europe are regularly converted to flywheel HP from WHP. This is a false assumption. There is no way to get that conversion even close. You have to measure it directly.

Next, fast burn is the reason we have problems with low octane fuel. The mixture burns faster then the cycle requires and puts too much pressure in the chamber before you get to TDC. The lowest octane fuel you can run without detonation will make the most power.

Next just because Ferrari developed the fuel doesn't mean it will work better for a rotary. The small compact chamber of the four valve hi compression engine is alot different then the "non-chamber" in the rotary. I don't have the knowlage to tell you what or if the difference is way out of the envelope for whatever fuel but I know enough not to think they are the same.

Consider this, the oil companys blend different fuels for the F1 teams for every different track they run at. So we know how hard they work at these things. Yet I gotta believe that the selling of this branded fuel is much more advertising then reality.

If your G-meter is telling you a difference under normal driving conditions then if they are true A/B tests I believe you have an improvement. But your numbers seem to be off of what we see here in the US. 162 whp is a number we might see here depending on what type of dyno it was run on. My own car made something like 150 WHP when new and we played with everything we could, even took it to Mazda USA. At later times it finally made 170 with no explanaition as to why. The only reason we still feel there is something wrong is that the curve is different then others.

But it does show that these cars are not repeatable unless you can hold everything in perfect order around your testing. I know for a fact that engine dyno numbers using the stock ECU and exhast they make between 212 and 219. On what flash this was I do not know. But the top HP probably does not change with the flash. At WOT and peak RPM there there is no EPA test so there is no reason for Mazda to hold back power there.

 

no it is not that is a misconception i am trying to erase

http://www.faqs.org/faqs/autos/gasoline-faq/part3/

read 6.2 and 6.3 especially

 

Lasse, do you have a 6speed transmission or a 5speed transmission?

 

I have a 6 speed. I'm loosing 76 hp in the drive train according to the Sun computer. Besides a Opel 2.4 litre engine with WEber 45 mm carbs dynoed 197 hp@6065 rpm and had only 49 hp in drivetrain loss but that was with a straight cut Quaife 5 speed dogbox gearbox. I put down 158,3 hp at rear wheels. The hp norm is DIN. I have some friends that also uses V-Power and they reported hp gain. Shell fuel is 99% Formula 1 gasoline and i have been told that the remaining 1 % the teams make for them self and can be of great gain hp wise.

Best Regards: Lasse

 

Please tell me how the dyno knows anything about what happens before the wheels. As far as I know the only thing that is hooked to the dyno are the tires.
Now if they put a strain gauge on the engine attached to the frame you might get a reading but there are still things attached to it that throw the reading off. And your losing something in the tires to rollers so it's not fair as an engine reading.

If they are using some sort of formula that is bogus. How does it know the difference between your gearbox and that other car with the race box. Do you tell it? Does it know if you are in direct gear or not and do you tell it if you are independent rear or swing?

 

Huh... It's difficult for me to answer your questions but i will try to come in contact with Sun Sweden and ask them! Anyway when i dyno it was in 5 th gear. And when the engine reach maximum rpm the dyno man depress the clutch and let it roll to zero which takes about 1 minute. I see here on my dyno paper that the rotating total mass is 360 kg and rotating test stand mass is 300 kg at last the rotating wehicle mass is 60 kg. Hope this helps a little bit!?

/Lasse

 

Europe dyno tests shouldn't be compare with US...

 

Also is this RON standard ? A 95 RON octane standard would be equal to a 90 octane US, and 99 RON = 94 US octane. I could see where the engine is retarding the timing a little bit as the engine is supposed to run on 91 octane, and might advance the timing a bit on 94 octane fuel. Not huge but maybe a bit. I had pointed out an article done by Car & Driver a while back where they put 87 octane in an M3 (high compression engine) and they lost approximately 12% performance vs. the 91 octane car.

 

great read!!

thanks.

beers

 

I know that launching has a lot to do with good 0-100km/hr times but I have had better results on my Gtech on my absolute worst launches .
No mods other than cat delete.
@ 15deg C with 1/2 tank of gas
average of three runs 6.4s worst 6.7 best 6.33

tried two different fuels :91 & 95 octane (RON) & got almost identical times

 

Nice article the only thing it's missing is the part about how Infra-Red energy contributes to the spontaneous ignition ahead of the flame kernal.

Combustion velocity and octane are two totally seperate elements. For the most part combustion velocity won't change by a lot so you'll get the same effect by changing the timing slightly.