LT1 11:1 Street?

[zgeezer]

Ok, here's the scenario. The JY shipped me a '96 LT1 out of a Caprice in place of an F-Body. After a few letters, he shipped me a set of Aluminum angle plug heads off of a "95 Z28". They look good. I understand that although the iron heads installed on Caprices have a larger volume combusion chamber than the aluminum F body heads, they have the same installed compression ratio of 10.5:1. This is so, according to the Impala web sites, because the iron head's head gasket is very thin. The NHRA blue printing site seems to back this up as it lists a thinner head gasket for 260hp LT1 than for the 275/285/300 hp aluminum headed LT1s. If a thin gasket is worth .5 compression points on iron heads, can it be used with aluminum heads for 11:00 cr? Please some thoughts. I expect to be running the LT1 fi, LT1 edit for the computer and one of Chevy's HOT cams [something compatible with the automatic], and headers.

 

"If a little is good, more is better, and too much is just about right".

 

gw

[Guest DRK]

Here is a link to TPIS. They sell a head gasket that is .010" thinner than a stock head gasket that yeilds 0.5 point more compression:

 

http://www.tpis.com/

 

Click on the 'TPIS Catalog' button, then on the left of the screen click on the 'gaskets and gasket sets' button.

[Guest Anonymous]

zgeezer,

I have a 93 lt-1 with the lt4 heads and hot cam, using the "thin" head gasket. I run the motor on 93 octane. Have had the car on the scanner doing 0-100 runs with no timing being pulled out by the computer. It works great for me should work great for you to. Mark

[zgeezer]

Thanks a lot for the posts. I still flinch at the idea of running something close to 11:1 on gas on the street. Mark, you must be running well on the other side of 11:1 b/c the LT4 heads were nominally 10.8:1. I'll go down to my Chevy agency Tuesday buy a set.

 

GW

[Guest Anonymous]

I drive a car everyday that has 11:1...it's a RSX-S though and the computer yanks gobs of timing when it gets above 95 deg outside.

[grumpyvette]

static compression means very little, the piston compresses nothing until the valves close. its the cam you use that will mostly determine the DYNAMIC COMPRESSION RATIO, thats important.

IM RUNNING A 11:1 COMPRESSION 383 ON THE STREET NOW, the ignition timeing, engine ECU that controlls the injectours and cam timeing allow it to run just fine

[pparaska]

Agreed. Check out Pat Kelley's Dynamic CR page/tool: http://cochise.uia.net/pkelley2/DynamicCR.html

[Guest JAMIE T]

I have the same set-up as Mark above. But, I'm getting timing pulled out with the scanner attached. I have Hooker Long tubes on my Z28, with the stock knock mudule. Right now I have the knock sensor bypassed though. I made it so it's easy to switch between knock sensor, and no knock sensor. BTW, I made 341 RWHP a few weeks ago

[Mudge]

I ran Impy head gaskets (.026" steel) on .010" shaved LT1 heads on 91 octane CALIFORNIAN gas just fine.

 

http://docmudge.tripod.com/dynorun030902/index.html

 

Alot of long tube users report false knock with LT1s on the FBody, I haven't heard the same be true of Impy guys though, so its a little bit of a mystery.

[quicker240]

This may be a little too simple but here we go.When putting together my first v-8 z engine,I was gifted a set of trw dome pistons.Being forwarned by all the goofy naysayers(you cant run those with pump gas!).But my old school engine builder expert said screw em'.His reply was that in a 2500 lb Z car,the engine would never really get lugged down like if it were in a 4500 lb pick-up truck so dont worry about it.I ran that 11:1 327 for 5 years ,autocrossing and all with no problems.I say go with it man,It'll work,and you will haul better booty!appx 15 hp per point of compression on a typical sbc.

[Mudge]

That is another good point too, timing will be different based on the weight of the vehicle and to some extent AF at WOT as well.