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Discussion Starter · #1 ·
Ok on 93 octane I am ~18.5psi and either 16 or 17 degrees timing if I remember correctly. Switching to E85 will I be better adding timing, adding boost or a mix of the two? What would be the optimum combo on E85 and a 2.8LH Kenne Bell?
 

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05 BOSS 302
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There shouldn't be anything stopping you from from upping the boost AND increasing timing with E85. Just make sure you are working with full summer blend E85 to get all the benefits from it.
 

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Discussion Starter · #3 ·
Ok. Any ideas how far I can go. This is southeren SC so we have the best stuff most of the year.
 

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05 BOSS 302
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I'd just ease up on the tune and see what the car likes. My combo is a bit different being a 3v and a Procharger, but my car made great power with 23 degrees of timing and 27psi of boost as an example.
 

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Ok on 93 octane I am ~18.5psi and either 16 or 17 degrees timing if I remember correctly. Switching to E85 will I be better adding timing, adding boost or a mix of the two? What would be the optimum combo on E85 and a 2.8LH Kenne Bell?
I would imagine the 2.8 KB is going to want to see alot more than 18.5 psi before it really hits its sweet spot, so you'll definitely need to crank up the boost. Then you can experiment with what kind of timing the car likes.
 

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Discussion Starter · #6 ·
I would imagine the 2.8 KB is going to want to see alot more than 18.5 psi before it really hits its sweet spot, so you'll definitely need to crank up the boost. Then you can experiment with what kind of timing the car likes.
The problem is I am pulleyed for 25psi but cams, stroking, and other things only see 18.5 or so.
 

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05 BOSS 302
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Sounds like you need a 3.6LC then!
 

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The problem is I am pulleyed for 25psi but cams, stroking, and other things only see 18.5 or so.
What kind of pulley combo are you running? I have cams (fairly tame though), headers, and Stage 2 ported heads and I'm hoping a 4 lb. lower, 3.65 upper gives me 22-23 psi with E85.
 

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3.75/6lb = 18.5 and at the very end will hit a little over 19.
:hmm: Perhaps the stroker motor is the real culprit. The 3.75 upper is pretty large, what about going to a smaller upper?

I have a 6 lb lower I could use to replace the 4lb I have on there and a 3.40 upper to replace the 3.65, but hopefully neither will be required for me.
 

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Discussion Starter · #12 ·
Right now I am seeing 15,773 blower rpms at 6500 rpms and the blower is only rated to 16000 rpms. So I may be out of room with this blower and may only be able to add timing. I would like the E85 swap to be worth it but if I can only run maybe 20psi max that may suck.
 

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05 BOSS 302
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The increased timing you are able to run vs. pump gas will be golden. Combine that with the evaporative cooling properties of E85 and you can also reduce the amount of timing pulled based on intake temp as well from what I have seen on my car with much increased knock tolerance than for instance, a 105 octane unleaded race fuel.
 

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The increased timing you are able to run vs. pump gas will be golden. Combine that with the evaporative cooling properties of E85 and you can also reduce the amount of timing pulled based on intake temp as well from what I have seen on my car with much increased knock tolerance than for instance, a 105 octane unleaded race fuel.
Are you mixing your own E85 or are you getting summer blend from the pump?
 

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I'm getting it straight from the pump, but I measure the ethanol content of every tank so I know what I'm dealing with.
 

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What kind of consistency are you seeing?
 

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I've been seeing anywhere from 80 to 90% alcohol content here in NorthEast Indiana.
 

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As we all know, boost increases the amount (mass) of air ingested, which means the engine can burn more fuel. Increasing spark timing further towards MBTT on the other hand, improves the so-called, thermal-conversion efficiency of the motor, (which is defined as the amount of work done over the cycle divided by the heat input from the fuel. Don't let anyone tell you that increasing timing closer to MBTT reduces efficiency, BTW. Yes...I've seen it posted.) As a general rule, the energy released by simply burning more fuel is going to "win" over efficiency gains from improved timing, at a given knock limit. That's why one can still make more power by increasing boost, while pulling timing at the same time. Just thought I'd add my thoughts.
 
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