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PostPosted: Sun Aug 19, 2018 7:30 am 
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Joined: Fri Dec 23, 2011 6:59 am
Posts: 1094
Location: Spring Hill, FL.
This may not be relevant to the Prod racers. I thought it would be an easy find for dyno runs with pure gas vs E10. Street 87 octane . I am still looking for back to back testing with 10% vs pure gas in a stock street type of engine with no tune changes.
I have found some theories. The E 10 has a little O2 but fewer BTU. Fuel burn is definitely greater with E10. The Ethanol may cool the intake charge a little and produce more power for more time in the 30 min races.
Others say that pure gas has more BTU and thus makes more power.

I dont know . And so far I cant find a definite answer. It may even be close enough to the same power that the pure gas may allow running at 5# lighter and thus show better lap times for the race duration.
The car in question is a Nissan Micra with 109 HP and post race weight of 2410#. The weight makes a difference. 10# shows up on the data. and lap times.
Thanks for any insight and esp actual dyno pulls.

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Mike Ogren/Protech Racing, http://www.FWDracingguide.com http://www.ogren-engineering.com/ 352.428-8983 mogren@tampabay.rr.com


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PostPosted: Sun Aug 19, 2018 7:52 am 
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I can't cite any tests, but E10 should - at ideal mixture in both cases - make a tad more power at the expense of a little more fuel burn, due to the sum of all the factors that you cite.

The ethanol's cooling effect should allow a bit more charge and possibly allow a tad more timing if you are knock limited. The lower btu content of ethanol (assuming correct mixture in both cases) won't decrease power as "correct mixture" implies extra fuel delivery in the case of E10.

A really valid back to back test isn't easy to do since things need tweaking (mixture and maybe timing) to optimize for each fuel, and the difference is likely small enough to be lost in the noise. Simply leaving things the same and switching fuels may show a difference but what is really being measured is which fuel better suits the exact setup of the car / engine in question. If everything is "right" on one, the other will test worse, unless the ECU is (using some combination of fuel sensing and wideband O2 control at WOT) compensating for the fuel change.


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PostPosted: Sun Aug 19, 2018 11:54 am 
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Joined: Mon Sep 09, 2002 1:57 pm
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Location: Hubertus, WI
Grassroots Motorsports published a test where they ran and tuned a car on a dyno using various fuels.

https://grassrootsmotorsports.com/articles/fuel-truth/

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(The other Damn Honda)
2011 H-Production National Champ


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PostPosted: Mon Aug 20, 2018 6:18 am 
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Greg Gauper wrote:
Grassroots Motorsports published a test where they ran and tuned a car on a dyno using various fuels.

https://grassrootsmotorsports.com/articles/fuel-truth/



This^^

93 E10 made the most power/tq.

93 E0 made less power and used 2% less fuel.


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PostPosted: Mon Aug 20, 2018 6:34 am 
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Joined: Fri Dec 23, 2011 6:59 am
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Location: Spring Hill, FL.
Thanks. That's exactly what I was looking for. I hope that it correlates to a stock engine with no adjustments.

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Mike Ogren/Protech Racing, http://www.FWDracingguide.com http://www.ogren-engineering.com/ 352.428-8983 mogren@tampabay.rr.com


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PostPosted: Mon Aug 20, 2018 7:14 am 
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Did a few google searches, but could not find the compression ratio of the car that was tested in the article.

Anyone know that detail of an autocross CSP?

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David Bednarz
FP Miata
Ann Arbor, MI


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PostPosted: Mon Aug 20, 2018 7:36 am 
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It must be relatively stock as it ran on 87 with only a degree less timing.


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PostPosted: Mon Aug 20, 2018 7:48 am 
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DavidBednarz wrote:
Did a few google searches, but could not find the compression ratio of the car that was tested in the article.

Anyone know that detail of an autocross CSP?


No porting. Stock cams. Stock rods and crank. Stock compression. +1mm bore.
Any throttle body and intake manifold. Any exhaust.

Csp miatas run the 2001 vvt heads and hogged out intake manifolds. Around 170rwhp last I looked.


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