What is the stock compression on the 91 l98 vs the 92 lt1?

And how much comp would you go if you used premium fuel only?
And what about vavle to piston clearence?

Thanks...

 

L98 compression in 91 was 10 to 1. LT1 in 92 was 10.5 to 1. I personally wouldn't go higher than 10.5. Much higher and you start looking at 95+ octane to keep from detonating

 

An LT1 can safely run in the 11:1 or low 12:1 range without problems on good quality pump gas. Gotta love reverse flow cooling :cheers:

 

An LT1 can safely run in the 11:1 or low 12:1 range without problems on good quality pump gas. Gotta love reverse flow cooling :cheers: [/QUOTE]

Good point. I forgot about that.

 

The premium fuel here in Sweden is 98 octane.
Is it ok to mill 1mm of the alu heads? Whan about piston to cylinder clearnce?

 

1mm? What is this you speak of?

Over here heads are milled using a measurement of thousandths of an inch. Something that is milled 30 thousandths is cut down .03 of one inch. So if we calculate it out what do we get.

There are 10 millimeters in one centimeter and there are 2.54 centimeters in an inch. Check my math here because it's early in the morning yet. That would mean that one inch is 25.4 millimeters? So therefore .03 of an inch = .762mm's ?

Milling an entire millimeter would be .039 inches, or approx 40 thousandths. You CAN mill them that much but I wouldn't really recommend it. Once the more you mill them the more it's gonna screw up your intake alignment. It will be possible that it would leak unless you get the intake milled as well. Piston to valve clearance SHOULDN'T be a problem but I can't promise it. Also you will want to pay real close attention, some heads can't be milled that much because it will mill into the valve seat.

Your best bet would be to mill them very little at a time until you have a clean smooth surface, mill them both the same. Then if you want higher compression you might try a thinner head gasket. :cheers:

 

ok thanks :)

 

Hej Devilfish

You can’t compare our Swedish 98 octane with the Americans 98 octane. We have different measurement systems.

In Sweden we measure in RON (research Octane) That is a value you get with static ignition and not so much heat.

MON is another measurement. Then you use variable ignition and more heat. It will knock easier and will give you a lower number.

USA uses a mean value of both. (RON+MON)/2

If you compare the Swedish gasoline with the American we can in Sweden find at best 93.75 (RON+MON)/2 (Shells 98 octane).
:cheers:

 

ahhh :) news to me... thanks :cheers:

 

Always glad if I can help someone :)
:cheers:

 

my 388 will be 11.5 compression. designed to run off 93 octane, but ill be using 94 anyways. Theres a whole deal on dynamic compression, static compression... so many little things to consider about detonation.