It's kinda boost related but kinda not.
I need to measure the difference between different thickness headgaskets.
Cometic only has .43 thick in the HP version and I didn't know that so now I have this thick *** gasket... stock is .29?
Well the new motor has 9:1 pistons in it.
How do I figure this out? I heard C speed is inaccurate?

 

You can use high school math to figure this out.

1. Figure out the total displacement for one cylinder.
2. Guess until you find the total cylinder volume (add the displacement to a variable that you are using for the volume of the combustion chamber at TDC) that yields a compression ration of what has been previously determined (9:1 in your case)
3. Subtract the volume calculated from multiplying the bore times the difference in thickness between the current gasket and the one you are thinking about using from the combustion chamber volume.
4. Keeping the same displacement, calculate the compression ration using the now smaller combustion chamber.

Confused yet?

 

Oh I left out a part, in step 2. the number you are guessing to find is the combustion chamber volume and to get the compression ratio you compare the total cylinder displacement (cylinder volume plus combustion chamber volume) to just the combustion chamber volume.

 

??? i always sucked at math.
isnt there like an accruate calulator or somethng ?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by itr206 &raquo;</TD></TR><TR><TD CLASS="quote">??? i always sucked at math.
isnt there like an accruate calulator or somethng ?
</TD></TR></TABLE>

I've got a book somewhere with the combustion chamber volume, and will give it a shot tomorrow morning (if I find it by then).

I wouldn't really worry about the compression ratio unless you really want that "number".

 

the prob is is i need to make big power. i dont wanna make it on 45psi , ok im being extreme, but i didint want toeven go as low as 9:1, let alone dip i the 8's
i dunno the guy who had the block built said the Je's were custom and 9.3 dome volume. he said he sent the specs to larry Endyne and guestimated it at 9.3:1 now?
he made 390whp on 10.5 psi on this block , but it seems sooo weird on such low compression , he dynoed on this same headgasket might i add.
i guess main thinh this comes down to is does Cometic make the HP gaskets in thinner styles? i coulda sworn after i returned the .43 alst time i got the HP in the .30

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by itr206 &raquo;</TD></TR><TR><TD CLASS="quote">... he made 390whp on 10.5 psi on this block , but it seems sooo weird on such low compression , he dynoed on this same headgasket might i add.</TD></TR></TABLE>

390 @ 10.5 psi seems damn impressive, and I'm wondering why it took Steve 20 psi to get ~389hp and 289 lb/ft out of my setup (on a quick hondata tune).

I'm jealous and pissed at the same time! (sort of)
I don't see the 390 @ 10.5 psi on a 9ish to 1 motor of ~ 1.8 liters of displacement.

As nice as it would be ....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dc231 &raquo;</TD></TR><TR><TD CLASS="quote">
2. Guess until you find the total cylinder volume </TD></TR></TABLE>

lmao, they call it algebra

 

algebra, whats that? I never heard of that word before

 

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

390 @ 10.5 psi seems damn impressive, and I'm wondering why it took Steve 20 psi to get ~389hp and 289 lb/ft out of my setup (on a quick hondata tune).

I'm jealous and pissed at the same time! (sort of)
I don't see the 390 @ 10.5 psi on a 9ish to 1 motor of ~ 1.8 liters of displacement.

As nice as it would be .... </TD></TR></TABLE>
not really a 1.8 anymore clsoe though .it was overbored to 84mm . his head was done up though too , not sure how much that had into affect

i called Cometic though a little bit ago , they do in deed have the HP in .30 i tohught i had one before , but for some reason they keep sending me .43's . i should have a new one MOn im assuming


Modified by itr206 at 7:03 AM 11/20/2003

 

Hey man, give me your bore and stroke, Your CR is 9.3 correct? and you are running the .43 gasket? I'll see what I can come up with here in the next few days.

 

Bore and stroke are needed because I don't know if they have been changed.

 

This link can prolly help you out.

http://www.c-speedracing.com/h...c.php