what head gaskets for Comp. ratio & PTV?
12-30-2007, 03:28 AM
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what head gaskets for Comp. ratio & PTV? I've been readin and searchin and searching and reading for a month now...
can quite seem to find anyone with the same setup.
My setup is:
from what i've researched it looks like that would put me at around 11.5:1
am I wrong? can I run that with 91 octane? will I be kissin my pistons?
I don't want to flycut so should I use thicker cometic gaskets? or will the GM MLS's work?
...and just for info I'm not too worried about cali smog, or daily drivability as the car just sits most of the time anyhow...
thanks so much in advance
Brian
can quite seem to find anyone with the same setup.
My setup is:
- stock '98 shortblock
- GTP stage 2.5 5.3L heads
- 2.055/1.60 valves, milled to 58cc, crane 835 dual springs
- MS3 cam 237/242 .603/.609 113 LSA
- all supporting bolt on's LT's, Ported LS2 intake, UMI 90mm TB, LM1 exhaust, etc
from what i've researched it looks like that would put me at around 11.5:1
am I wrong? can I run that with 91 octane? will I be kissin my pistons?
I don't want to flycut so should I use thicker cometic gaskets? or will the GM MLS's work?
...and just for info I'm not too worried about cali smog, or daily drivability as the car just sits most of the time anyhow...
thanks so much in advance
Brian
12-31-2007, 03:10 PM
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Definitely check your clearances. With the 5.3 heads running big valves and 58cc chambers, IMO you are cutting it pretty close. My cam is a bit smaller than yours, (232-236/.595/.601 on 114+4 lobe) and I have the same size valves in 243 heads milled to 58cc, and I had to fly cut to insure enough clearance. (went .080=2cc) and that is with a stock GM gasket. HTH
As long as your tune is spot-on, the 91 octane gas won't be a problem,,,,mine runs fine on it here with 11.5 to 1 scr
Jimbo
As long as your tune is spot-on, the 91 octane gas won't be a problem,,,,mine runs fine on it here with 11.5 to 1 scr
Jimbo
12-31-2007, 03:25 PM
#4
You need to read more. Read about quench distance, this shouldn't be more than .045 IMO thicker head gaskets increase quench distance.
Get the tools and learn how to measure your combustion chamber volume, this way you're not guessing at compression.
Thicker gasket just so you don't have to flycut....not the way to build an engine.
Sure you can run 11.5:1 static, but you need to know what your dynamic CR is, it's not always a guaranteed figure but if you have 11.5:1 SCR and 9.5:1 DCR it's never going to run right on 91 octane to say the least.
Get the tools and learn how to measure your combustion chamber volume, this way you're not guessing at compression.
Thicker gasket just so you don't have to flycut....not the way to build an engine.
Sure you can run 11.5:1 static, but you need to know what your dynamic CR is, it's not always a guaranteed figure but if you have 11.5:1 SCR and 9.5:1 DCR it's never going to run right on 91 octane to say the least.