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 Post subject: Re: E85??
 Post Posted: Sun Nov 20, 2011 3:25 pm 
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Ah, Scott's engine is single carb. Mine is presently on 2 750s on a sheetmetal intake. :-k

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 Post subject: Re: E85??
 Post Posted: Sun Nov 20, 2011 4:28 pm 
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Location: Montgomery, Alabama
shrinker just to make sure we are on the same page my Combo is a 421" (3.675 x 4.165) SB2 with 46cc chambers and a flat top piston at just about zero deck.
Cam is 279/288 @ 110 ground on a 112 LSA.
Pumps 235 cranking compression.
Single carb and cast intake.


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 Post subject: Re: E85??
 Post Posted: Thu Nov 24, 2011 6:10 pm 
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Location: Adelaide Australia
Hi Scott, 235 lbs is not much cranking pressure for alcohol fuel to handle. Your compression ratio might be 15.3 etc but your not trapping much air. The cam is bleeding off a lot of air before the valve closes. I would see no problems running that engine on E85. In fact I think the problems would be reversed, it doesnt have enough compression to run 105 MON fuel unless the fuel is completely vaporized. I think you have this situation, your firing time has to be retarded because the chemicals present at that time are the wrong ones for the lean AFR that exists at firing. Some time after firing the AFR will go much richer due to the heat from the burn vaporizing the higher distillation chemicals. What your fighting is lack of heat transfer time to vaporize the chemicals that you need, Shut the valve earlier, and it will be a totally different engine.
SB-2 heads flow a lot of air and can fill that size cylinder basically as its going down, they wont need much bottom fill time. You have pretty good stuff there so you'll likely have lots of valve lift say over .800" If thats the case then it not going to need a long bottom fill time like your cam is giving it.
Your cam is 2 degrees advanced I suppose it goes better that way, thats because its too long on the bottom fill. 15.3 Compression ratio should pump around 280+ PSI.
But thats just my thoughts.


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 Post subject: Re: E85??
 Post Posted: Thu Nov 24, 2011 10:57 pm 
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Scott Smith wrote:
shrinker just to make sure we are on the same page my Combo is a 421" (3.675 x 4.165) SB2 with 46cc chambers and a flat top piston at just about zero deck.


Umm isnt that a 400


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 Post subject: Re: E85??
 Post Posted: Thu Nov 24, 2011 11:28 pm 
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I think he mistyped, should be 3.875 stroke.


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 Post subject: Re: E85??
 Post Posted: Thu Nov 24, 2011 11:38 pm 
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Fair enough then.
So its trapping air like its shut the valve at 93 ABDC.


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 Post subject: Re: E85??
 Post Posted: Fri Nov 25, 2011 11:28 am 
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Quote:
Compression ratio should pump around 280+ PSI.


If it was 280 @ cranking it would need Diesel fuel.
Even Pro Stock shoots for 220 to 240 cranking compression.


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 Post subject: Re: E85??
 Post Posted: Fri Nov 25, 2011 1:14 pm 
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Hi Scott, for example our engine cranks 275 with the 14.8 compression ratio that it has at the moment. It pumps 190 on the first pump and 275 second pump. The gauge is the screw in type with the hose.
Times before it had 15.3 and also 15.8 and it cranked 285 and 300 psi. It runs C14+ and we have run it on Roo16, C16, C25, Q16. There is no detonation and the knock sensor doesnt detect any. It runs typically 29 to 32 degrees on any fuel without detonation. It runs at 12.8 to 13.1AFR on any fuel. I have tested the cranking pressure with electronic sensors to verify gauges and data logged the pressure on oscilloscopes. Its accurate information.
My sons 308 holden cranks 200 psi on the first pump and 240psi on the second pump and nails it on the second. It runs street unleaded with no detonation.
We raced a Mitsubishi V6 on methanol with 240 psi cranking compression with no issues.

These cranking pressures can definitely be run however you have to have vaporization and homogenization to run them successfully.
Lots of people run higher octane fuel than what they really need to prevent detonation caused by lean burning at the early stages of the burn caused by lack of vaporization.


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 Post subject: Re: E85??
 Post Posted: Mon Nov 28, 2011 1:23 am 
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Location: Jefferson City, Missouri
Scott, I did a single Dom for an ex Steve Schmidt Pro stock engine that was around 499ci and 16:1, it had a fabed up single carb hogan intake on it....yours should work.

I feel your SB2 would be fine.....and your 2 circuit calibration is not far off from the Q16.

a customer that runs 8.60s wot and stops his car down to a 10.90 was running Q16.....he reported that he picked up ET (into the high 8.40s)....but lost mph = .3

important thing to remember....try and stage the car warmer than normal....I try to go to the beams at 170.....usually see about 177-179 in the 1/4 traps.

Ethanol does not turn to vapor until it hits about 173*.


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