Originally Posted by 18psi
(Post 1351976)
12.5 or more if you can find the pistons
Originally Posted by nitrodann
(Post 1351995)
Ive got 2 builds at just under 12:1 at over 25psi.
Both are awesome and not even close to knock. Dann Dann, how much over 25psi? 26, 30, more? |
Originally Posted by 18psi
(Post 1352254)
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+ https://cimg1.ibsrv.net/gimg/www.mia...b7c32f415b.png |
Much better.
|
Originally Posted by patsmx5
(Post 1352291)
Thanks. I was thinking around 12:1 or so if I make the switch.
Dann, how much over 25psi? 26, 30, more? I didnt get to the tuning laptop today also guys |
Originally Posted by nitrodann
(Post 1352415)
Yeah 26-27
I didnt get to the tuning laptop today also guys |
Maybe, Im just picking numbers by memory.
Ill show you the exact map. Dann |
Yep better, and make sure your AFR's aren't dipping below 11.8 or you might get misfires from that too. You've still room for more advance too, this is on the conservative side
|
Originally Posted by 18psi
(Post 1352437)
Yep better, and make sure your AFR's aren't dipping below 11.8 or you might get misfires from that too. You've still room for more advance too, this is on the conservative side
|
nah it's probably fine at 11.8, but once you start dippin lower by too much, you'll start losing spark. you're pumping ~30% more of the stuff into your cylinders, it overwhelms the spark
|
Even while running boss d585 coils and a reasonable spark plug gap?
|
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 |
Pat I think you're capable enough that I can remind you to disregard static, and focus on dynamic compression ratio. If you fuck up and end up with too much static, so you have to pull so much spark it makes less power fix it is just a cam timing adjustment away.
|
Originally Posted by Leafy
(Post 1352674)
Pat I think you're capable enough that I can remind you to disregard static, and focus on dynamic compression ratio. If you fuck up and end up with too much static, so you have to pull so much spark it makes less power fix it is just a cam timing adjustment away.
I run 17* @ 38 PSI with no knock. Not going higher till I get it on a dyno. |
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. :eek3: |
YES!! do it for science.
Although a local buddy of mine is running 12:1 already on a miata that traps 132mph currently. So you gotta go higher to blaze new trails :likecat: |
Originally Posted by 18psi
(Post 1437840)
YES!! do it for science.
Although a local buddy of mine is running 12:1 already on a miata that traps 132mph currently. So you gotta go higher to blaze new trails :likecat: I am tempted to go higher. |
Yes, Yes, cornjuice of course. It's been at least a year and I wann say a couple dozen passes? I'll ask him to chime in or at least fwd me the details. but he beats on it like a redheaded stepchild very very often. this is by no means a garage queen
|
Originally Posted by 18psi
(Post 1437844)
Yes, Yes, cornjuice of course. It's been at least a year and I wann say a couple dozen passes? I'll ask him to chime in or at least fwd me the details. but he beats on it like a redheaded stepchild very very often. this is by no means a garage queen
|
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! |
Originally Posted by k24madness
(Post 1437936)
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! 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. |
All times are GMT -4. The time now is 07:56 AM. |
© 2024 MH Sub I, LLC dba Internet Brands