E85 and boost, what compression ratio could I run?
#22
Yeah, you can run way more.
19kpa cruise should be 40*
taper to
100kpa should be at least 27-30*
taper to
230kpa 16* is ok but should not be dropping, should be ramping up to redline, to at least 20*
Assuming built engine, competent setup, and at least e70 actual in tank, preferably 80+
19kpa cruise should be 40*
taper to
100kpa should be at least 27-30*
taper to
230kpa 16* is ok but should not be dropping, should be ramping up to redline, to at least 20*
Assuming built engine, competent setup, and at least e70 actual in tank, preferably 80+
#28
Really? Damn e85 must really be some magical unicorn gizz. It only takes 11.8 to be rich enough to misfire? I figured it was closer to 11. Because it's definitely dropping below 11.8 at some points. It's already pulling much cleaner and harder so I'll keep playing with it. I'd still like to see what other people are running
#31
with those you're likely fine, but I'd still run 12:1 on the dot cause it should be a wee bit faster and waste less fuel.
On Ryan's built 1.6 we could only go up to 21-22psi due to weak spark, but we still ran 20* midrange tapering up to 30* up top. that car put down 360whp on a 1.6 and a log manifold and a chinacharger. we've done BP4W's similarly and it was over 400whp.
the stuff is pretty nuts
On Ryan's built 1.6 we could only go up to 21-22psi due to weak spark, but we still ran 20* midrange tapering up to 30* up top. that car put down 360whp on a 1.6 and a log manifold and a chinacharger. we've done BP4W's similarly and it was over 400whp.
the stuff is pretty nuts
#33
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I run 17* @ 38 PSI with no knock. Not going higher till I get it on a dyno.
#34
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Year long bump. I searched the forum to see if anyone is running high compression + boost, and found my own thread discussing this...
Getting bored, thinking of putting together a new shortblock to experiment with some things. One being high compression. Current thought is to try AT LEAST 12:1 with E85/Boost. Actually thinking about going to 13:1 or even 14:1 and see what happens. Would have to get custom pistons made to do this, looking into that now.
Getting bored, thinking of putting together a new shortblock to experiment with some things. One being high compression. Current thought is to try AT LEAST 12:1 with E85/Boost. Actually thinking about going to 13:1 or even 14:1 and see what happens. Would have to get custom pistons made to do this, looking into that now.
#39
I run 11:1 with 9psi with a Rotrex on E85. The cams have shorter seat timing than stock further bumping static compression, Not extreme but it is a track car that gets flogged hard!
I suggest you start from the top and work your way backwards. Determine whatever you plan to run (15-20-25psi) to meet your HP goals and then fill in the compression that keeps your dynamic numbers sane. Somewhere around 18:1 is what I shoot for. I have another marque I build using the same formula. Been running 10+ years strong on the street with some track days sprinkled in.
This is a pretty good tool to help you play with some numbers. Wallace Racing: Dynamic Compression Ratio Calculator
The extra compression buys you more HP per PSI of boost. The motor tends to be much more lively in transient phases and just rips WOT. Good Luck Pat!
I suggest you start from the top and work your way backwards. Determine whatever you plan to run (15-20-25psi) to meet your HP goals and then fill in the compression that keeps your dynamic numbers sane. Somewhere around 18:1 is what I shoot for. I have another marque I build using the same formula. Been running 10+ years strong on the street with some track days sprinkled in.
This is a pretty good tool to help you play with some numbers. Wallace Racing: Dynamic Compression Ratio Calculator
The extra compression buys you more HP per PSI of boost. The motor tends to be much more lively in transient phases and just rips WOT. Good Luck Pat!
#40
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I run 11:1 with 9psi with a Rotrex on E85. The cams have shorter seat timing than stock further bumping static compression, Not extreme but it is a track car that gets flogged hard!
I suggest you start from the top and work your way backwards. Determine whatever you plan to run (15-20-25psi) to meet your HP goals and then fill in the compression that keeps your dynamic numbers sane. Somewhere around 18:1 is what I shoot for. I have another marque I build using the same formula. Been running 10+ years strong on the street with some track days sprinkled in.
This is a pretty good tool to help you play with some numbers. Wallace Racing: Dynamic Compression Ratio Calculator
The extra compression buys you more HP per PSI of boost. The motor tends to be much more lively in transient phases and just rips WOT. Good Luck Pat!
I suggest you start from the top and work your way backwards. Determine whatever you plan to run (15-20-25psi) to meet your HP goals and then fill in the compression that keeps your dynamic numbers sane. Somewhere around 18:1 is what I shoot for. I have another marque I build using the same formula. Been running 10+ years strong on the street with some track days sprinkled in.
This is a pretty good tool to help you play with some numbers. Wallace Racing: Dynamic Compression Ratio Calculator
The extra compression buys you more HP per PSI of boost. The motor tends to be much more lively in transient phases and just rips WOT. Good Luck Pat!
7.96 dynamic compression ratio
29.62 effective boost compression ratio.
That is already significantly over your 18:1 sane numbers.
If I ran 12:1 and 35 PSI boost:
10.57:1 dynamic compression ratio
35.74:1 effective boost compression ratio.