that makes me feel a lot better!! saves me some loot thanks griff!!

Good info, thank you.

Over 700hp what do you recommend on size and windage screen set up (in pan on caps)?

Ok came across a set of rods and Pistons, that I can use but the rods are 6.358"not the original 6.135" and the Piston compression height is 1.365" not the original 1.645"

​​​​​​What would be the positives and negatives of running the shorter compression height (top ring land is .400 down so top ring is not a concern) with the longer rod vs the stock set up.?

What changes to the power curve & engine longevity would this set up make?

And would I need to change any of the machining, clearances etc if I go this route?

Ok we'll see if this gets any traction :sport009:

​​​​​​Finalising the rods and Pistons so I need to decide on how I'm setting up the heads and static compression ratio. I'm heavily leaning towards the EQ320 and with the 177 spun at 2.44:1 and a super chiller which eats 2lbs boost. (According the the weiand chart that puts me at 9.4lbs -2 for chiller = 7.4lbs boost =effective of 12.5:1), SO based on piston & rod selection I'm going to be .010 in the hole and 8.51:1 static.

If I'm going with iron heads is this a little high to run on pump 89 gas?

I was thinking of running a .060 mls instead of a .040 with the taller quench to help stop detonation...OR is it better to try and get the compression ratio down to 8.0:1 or 8.25:1 with piston selection rather than running a taller quench?


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Get it lower with the pistons or by enlarging the chambers on the heads.
Increasing the quench beyond about .060 will actually increase the risk of detonation.
Adverse effects of too much quench? - Yellow Bullet Forums

Thanks Griff, I understand quench and it basic effects, I have a high HP 2 stroke and it's squish and squish band in that head, which is the basic equivalent to quench in this car motor.

From what I've read the top end of pump 91 (which is max I can get in suck-a-fornia), is 12.0:1 ??

If I wanted to run 89, what effective compression ratio is about the max i could run with a flat top with 2-3cc valve reliefs, .010 below the deck, and a .038 compressed MLS, with non ported EQ320 heads?

Thanks

If youre using a flat top, a .040 gasket, and a 119cc chamber head with the piston .010 below, you should end up at 8.25 or so, maybe even lower.

i wouldnt worry about the quench issue on a blower motor. Guys are running with pistons way further down the hole these days.

being 89 octane, id prob keep the boost to about 5-6lbs max, and have a good timing curve , and not locked timing. Jmo.

I've ran the numbers here Compression Ratio Calculator | Tools | Diamond Racing Pistons and it comes out to 8.51:1 with the 6.385 and the 1.395 comp height.

... So what's about the max effective compression ratio to run 89?

are you entering plus 2 or 3cc, or minus 2 or 3cc for the valve relief in the calculator

You're right MT, I misplaced the decimal on the head gasket bore diameter and now that I've corrected it I'm at 8.0:1, so with 7.0-7.5lbs boost post chiller that puts me right at 12.0:1 effective or just a hair under.

So what's the upper compression limit on 89 octane?