I put on a GReddy 2 mill headgasket...

Compression readings are

#1 130
#2 125
#3 120
#4 140

I'm within the 28 recommended variance, but I'd like some opinions on these numbers...is this the correct drop in compression for a thicker head gasket?

 

man I wouldnt drop compression at all on your motor. It seems like a 1.6 with low compression would be really sluggish?? However, that looks about right.

 

reason for dropping compression is so I can increase boost to 10 to 12 psi (it is currently at 7psi)...once that is done I should have an overall gain in WHP (from 170 to 200)...at least in theory. And, this is better on the engine as the compression is lowered.

Any opinions on this????? I'd like to hear 'em.


[Modified by greyzone, 8:11 PM 6/17/2001]

 

I had the same setup as you. Lowered the compression with a Greddy 2mm headgasket. I was boosting 15 lbs daily w/ occasionally boost spikes of 18lbs. Not the slightest bit of detonation. When before, with stock compression I detonated at like 8 - 9 lbs. I ran a 13.7 with street tires on my SOHC setup @ 15 lbs here in Vegas (2600 ft above sea level).

Forget boosting only 12lbs. Boost 14-15lbs at the track and have fun with that ****. The stock internals can take up to 250 hp.

It didn't even feel that bad after the install of the head gasket when out of boost. Wasn't even that much difference in power.

 

what does that gasket bring compression down to? Couldnt you make the same power with stock compression and less boost with the right fuel and timing? I dont know, I usually dont like the idea of using headgaskets to adjust compression, same with milling heads. although I used to know a guy with a SOHC boosting 15 psi with FMAX kit, he put out 236 hp, and it's still going for over 3 years.

 

Its a safety issue, for higher boost pressure, the lower the base compression in the engine block the higher you can SAFELY boost with (mostly) stock internals.

So, (check my compression numbers above) it much safer to boost 14 psi with my compression numbers than to even try and do it wiht stock compression of 175-180. That would be kindof insane and probably blow the engine before too long.

Remember, a LOT of experienced people will tell you NOT to boost past 6 or 7 psi on a strickly stock engine...but block gaurd, 2 mill headgasket (to lower compression) and ARP headstuds can get you safely to 225WHP and possibly (see post above) even higher. Of course, you also need intercooler, boost controller and SHOULD have MSD BTM ignition (for kick *** low end AND retarded boost)...

its so cool when you do it right, and so expensive and frustrating when you dont!


[Modified by greyzone, 11:13 PM 6/17/2001]