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Target Static compession on E85?

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Old Nov 6, 2007 | 04:51 PM
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Default Target Static compession on E85?

Thinking about going "on the corn" with a 408 CI LSX, using either LQ9 heads that I have now or switching to L92 heads and the GMPP single plane.
What seems to be the ideal compression ratio when running E85? Do you want to have a higher compression ratio when going to E85 or stick with 8.2-8.7 static and turn up the boost???
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Old Nov 6, 2007 | 05:35 PM
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We usually use 9.0 compression up to 28-35 psi (on small import engines).

I really recommend E85, more power then VP csp and other racefuels..
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Old Nov 6, 2007 | 06:50 PM
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Is it true about you have to move more volume with E85?
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Old Nov 6, 2007 | 07:24 PM
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ya i would do 9.0-9.7 but i havent run it yet and am just guessing
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Old Nov 6, 2007 | 08:20 PM
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a wide band doesn't go down that low. How would you know?
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Old Nov 6, 2007 | 08:22 PM
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is that also all you would change with the tune?
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Old Nov 6, 2007 | 08:57 PM
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Originally Posted by 02SSLE
a wide band doesn't go down that low. How would you know?
A wideband doesn't care about ratio, only Lambda. Tuning for 14.7:1 AFR (lambda 1.00) on gas and then switching to E85 will still net you a stociometric mixture (lambda 1.00).

Widebands don't care what the fuel source is.

If I run 11.0:1 AFR on gas and then go e85 and still use the same wideband, I'd still target 11.0:1 AFR on the wideband and it would be the correct mixture. The wideband would just be displaying an incorrect AFR for the fuel but would still be correct because the lambda is the same.
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Old Nov 6, 2007 | 09:05 PM
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Originally Posted by Zombie
A wideband doesn't care about ratio, only Lambda. Tuning for 14.7:1 AFR (lambda 1.00) on gas and then switching to E85 will still net you a stociometric mixture (lambda 1.00).

Widebands don't care what the fuel source is.

If I run 11.0:1 AFR on gas and then go e85 and still use the same wideband, I'd still target 11.0:1 AFR on the wideband and it would be the correct mixture. The wideband would just be displaying an incorrect AFR for the fuel but would still be correct because the lambda is the same.
what is lambda?
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Old Nov 6, 2007 | 09:07 PM
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Originally Posted by 02SSLE
Is it true about you have to move more volume with E85?
yes...you must add about 30% more fuel to the injector tables.
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Old Nov 6, 2007 | 09:12 PM
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Originally Posted by MECHAM
yes...you must add about 30% more fuel to the injector tables.
So do you know this first hand or are you quoting something that you read?
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Old Nov 6, 2007 | 09:19 PM
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9.7 Here and yes AFR gauges do go that low you just need to set it up for the right fuel. Just off the top of my head gas/14.7=E85/9.0
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Old Nov 6, 2007 | 09:19 PM
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Originally Posted by 02SSLE
So do you know this first hand or are you quoting something that you read?

https://ls1tech.com/forums/showthrea...&highlight=e85

read the negatives...have seen other non ls1 tuned...but imports with low impedance injectors. 1000+ cc's so they have enough injector to run it and high boost
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Old Nov 7, 2007 | 02:24 AM
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I will have 8pcs 160lb on my LSX engine..
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Old Nov 7, 2007 | 06:23 AM
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i thought we are talking about setting up the compression ratio for the engine, not the AFR
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Old Nov 7, 2007 | 07:47 AM
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Originally Posted by smokinHawk
i thought we are talking about setting up the compression ratio for the engine, not the AFR
Yes... back to topic.
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Old Nov 7, 2007 | 07:48 AM
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In general with NA applications, you have to run a lot more compression with ethanol than gas to achieve the same power level on similar setups. If you are going to run about 15psi, you can pretty easily run 10:1 static compression. That is the beauty of ethanol, is that it is highly resistant to pre-combustion detention.

Of course there is the down side in that you will have to run a lot more fuel. Gas requires 14.7 oxygen molecules to burn one, while ethanol is around 9 I believe.

Keith
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Old Nov 7, 2007 | 08:02 AM
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NA engine gives ~ 10% more power with E85 then pumpfuel. With the same compression..
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Old Nov 7, 2007 | 10:50 AM
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I am aware of the added fuel delivery needed, and ~30% seems to be the magic number. IE BIG pump, lines and 160# Injectors....... I got that.

What I am after, is knowing that E85 will support, and works best with big compression (NA for example 14-15 to 1) Is it benifical to raise the static compression on a boosted application, or leave it low IE 8.5 to one and run more boost???

Just FYI there is a good thread in the Fueling section of this board dealing with the ins and outs of E85
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Old Nov 7, 2007 | 01:10 PM
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You don´t need to raise the compression with turbo. Just boost a little more..
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Old Nov 7, 2007 | 01:32 PM
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Originally Posted by camaroandreas
NA engine gives ~ 10% more power with E85 then pumpfuel. With the same compression..
My experience is a little lower around 5%... But i might be wrong.
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