Recently checked my piston to deck clearances, and my pistons are .005 above the deck. I think from the factory, honda's pistons are .015 below the deck or in the hole (correct me if I'm wrong). Considering that oem headgaskets are .027 thick + .015= .043 is the amount of clearance in an oem block. Would it be wise to purchase a headgasket that has a thickness of .048? (.048-.005) This way my clearance will equal .043. However, I've heard rumors not to get a headgasket that's any thicker than .036. Any reasons for this?

 

Lower compression ratio, other than that I don't know of any problems with a thicker headgasket. BTW, what do you drive I'm in the Vandalia area might have seen you around.

 

all these will determine:

bore
static compression
need to know if stock rods and rod bolts
how high you revving motor

from these things you can determine the safe clearance.


Greg

 

Thats a good question, honestly though. I dont think its a good idea to use a thicker head gasket to increase a deck height. You might have head gasket problems. good luck either way though.

 

you shouldn't have any problem running thicker head gasket. there are lots of boosted guys running .05+ head gasket and pushing 300+ hp with no problem. i ran cometic .053 on my boosted b16 and had no problems at all. just make sure you have a set of cam gears to zero out the cam timing.

 

Correct me if im wrong but I thought one problem with using a thicker headgasket is that it decreases the efficiency of the quench area on the cylinder head making the engine more prone to detonation.


Modified by wiseman at 12:45 PM 3/9/2005


Modified by wiseman at 1:05 PM 3/9/2005

 

wow - something i never considered - if anyone can expand on this "quench area" topic, i'd be really interested in learning....

 

cheetah: bore is 84.5mm, eagle rods with arp rod bolts, motor will be built to rev to 9. Static Compression- hmm, not sure. I wanted the thicker head gasket to make up for what they took off the deck so I thought optimally I should keep clearances close to stock (.043), and I'm looking to have adequate piston to valve clearances for dialing in the cam gears. Plus I don't want the c/r to be above 12.5-1. Any suggestions?

b16sellout: I actually live in Troy, now, I have a white DA w/ white rims. What city do u live in?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nissanjon &raquo;</TD></TR><TR><TD CLASS="quote">wow - something i never considered - if anyone can expand on this "quench area" topic, i'd be really interested in learning....</TD></TR></TABLE>

Even though using a thick head gasket is a cheap and easy way to lower compression it is more likley to blow out because there is more surface area around the bore.

As for the "quech zone" the cylinder head has an area that is designed to promote complete burn of the a/f mixture. The quench zone (the flat area of the combustion chamber) comes into to play when the piston is at TDC, because the quench increases the turbulance of the a/f mix by forcing it towards the sparkplug and away from the flat area of the chamber. When u increase the volume of the quench u decrease its effectiveness of controlling the burn.

 

Im not saying that thicker head gaskets can not be used succesfully, because they can. They should be used carefully. For example if a thick head gasket is used to lower the compression to 8.5:1 it may have a detonation threshold of 9:1 because of the loss of the quench efficiency.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Nisif &raquo;</TD></TR><TR><TD CLASS="quote">cheetah: bore is 84.5mm, eagle rods with arp rod bolts, motor will be built to rev to 9. Static Compression- hmm, not sure. I wanted the thicker head gasket to make up for what they took off the deck so I thought optimally I should keep clearances close to stock (.043), and I'm looking to have adequate piston to valve clearances for dialing in the cam gears. Plus I don't want the c/r to be above 12.5-1. Any suggestions?
</TD></TR></TABLE>

use a 043 gasket, assuming you have the 3/8" arp rod bolts ... even at 9k rpm they dont stretch too much. 84.5mm bore pistons are not too heavy, cause that makes all the difference in the world when the motor spinning and how the whole assembly goes towards the head.

Use some arp head studs and torque down an extra 5-7 ft-lbs as well.


Greg

 

how come p72 heads have quech area on the combustion chamber and pr3 heads don't, yet pr3 heads are used for type R engines. just curious.

 

cheetah, thanx for the advice

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rice4life &raquo;</TD></TR><TR><TD CLASS="quote">how come p72 heads have quech area on the combustion chamber and pr3 heads don't, yet pr3 heads are used for type R engines. just curious. </TD></TR></TABLE>

The pr3 head does have quench areas they are just shaped differently then the gsr head.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by wiseman &raquo;</TD></TR><TR><TD CLASS="quote">

The pr3 head does have quench areas they are just shaped differently then the gsr head.</TD></TR></TABLE>
just bump the comp up on the motor a little bit, caues they have a smaller combustion chamber...