Yesterday i dyno'd a baseline static pull of 213.5hp@hub on my RotoTest. Next i switched to a mix of 70% Shell 99 and 30% E85 with no premix. I was hoping for some 5-7 hp in upper range but was dissapointed as the output was lower on all revs. I lost about 2-4 hp even though i mapped between fat lambda 0.84 and lean lambda 0.88-0.90. I did map in 1+ ignition and saw for 1-2 sec 10kw more power but then the knocksensor override it and i went back to lower than before hp. Any suggestions and comments is appriciated!

/Lasse

 

try taking away timing - 6000 through to redline .
I ended up with minus 6 deg for best power once fuel was re-dialed in.
Let us know what happens ...

were you running premix for the first test ? what ratio ?

 

I will try that! I have never used Pre-mix. Of course i will let the RX-8 club know when i have dyno'd again!

/Lasse

 

try premix at 80:1 as per Racing Beat

 

What type of fuel did you dyno with?

/Lasse

 

You shouldn't be surprised at your power DECLINING when using a higher ratio of ethanol. I'm assuming you did this, since you said you "switched to" a fairly high ethanol blended mix. Ethanol fuel has approximately 10% less bang per ounce than gasoline. If you want more power, stay as far away from ethanol as you can. It will reduce your fuel economy and power.

 

+1

Ethanol can help increase power in piston engines by allowing an increase to the compression ratio, but for a fixed CR rotary, its best to stick to gasoline. In small amounts, it can be used to increase the octane rating of the fuel, but that doesn't increase power at all unless you increase timing or CR.

Same thing goes for 99 octane gas- no extra power in the gas, only in what it allows you to do.

It's usefulness changes when you add forced induction, though....

 

The only way I know of to get more power with ethanol is through forced induction and even then only because boost can be raised due to a higher octane. A higher compression ratio on a naturally aspirated engine could offset the power loss somewhat but I still don't see it gaining power in the end. At best I see it breaking even if the motor was built around it. It would still have much worse gas mileage though. My opinion on the fuel is that if you aren't using it for forced induction track use, save it for the Vodka bottle.

 

I agree with your post. The only thing is you have to remember outside of the US octane is rated differently. U.S. is RON + MON/2. I don't know exactly how sweeden does it but I'm pretty sure its not the average like it is here.

 

That is a common misconception brought out in todays society of hap-hazardly put together "Flex-Fuel" engines.

You can easily get more power and more efficiency from ethanol. In order to do it though you must take advantage of one or both of ethanols property advantages over gasoline...

a) Higher octane rating - you need to run: more boost, higher compression, and/or more aggresive timing (up until the point your no longer increasing performance). On a NA RENESIS the first two are not options at all and the third (bumping up timing) is a subject that needs to be carefully experimented to work well on a rotary engine.

b) Evaporative cooling effects - ethanol will cool the air/fuel charge dramatically when done correctly... too bad for us (currently) direct injection is the best way to harnass that advantage.

 

95 octane which is 91 in US . we have 91 95 & 98 here .
The lower octane gas has shown good results in US and I ran 91 for ages but decided not to risk it after I had bad detonation after idling around one hot day .

 

I have tried E85 today. I must say that the amount of alcohol being injected in the engine was bigger than i expected. On the Interceptor values of 35,50 and up to 90 were used in the cells, and it's very difficult to tune to! Lambda readings were fluctuating. I added 8 deg of more ignition to the ignition map but can't if that,s the optimum. Anyway did a 5000 rpm pull and made 142hp@wheels comparing to 134.5hp@wheels with gasoline. Many hours is left on tuning the E85 beast!

/Lasse

 

E85 in a Renesis is certainly possible, but the first place I would start would be the injectors - the stockers would JUST do the job, but if you intend to tune for MORE than stock power, they are totally inadequate.

If the injector capacity is exceeded, you go lean, and that leads to short apex seal life.

(I'm not sure I would trust a normal wideband sensor in E85 service - it may get confused by the oxygen inherent in the fuel....)

S

 

I have not dyno test any more with E85 since October but i have bought 4 bigger injectors from Mazsport. I will probably test more with E85 this spring.

/Lasse