BIGBOS

My heads were sent out to get the CC's measured...

Stock 5.7L heads are 67cc's

Mine measured out to be 61.6cc's...

which means they are milled to about .030" right??

11:1 compression... <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />

And these heads were supposed to be stock compression... <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" />

Fly By

11:1 + Boost = <img border="0" alt="[bomb]" title="" src="graemlins/gr_bomb.gif" />

BIGBOS

Yea, I experienced this...

TTT on this..

Fly By

just build the bottom end on that thing. Some nice Diamond slugs <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

Or go to a thicker HG from cometic, but you will only gain 20 thou from that. <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

BIGBOS

Diamond slugs are almost 1000 bucks...

I would rather sell the heads, get 6.0L, and just get boost pistons...and still have a safe C/R

ZYA_LTR

Bos Diamond pistons can be had for much less than a grand, i got my custom made pistons for 800 bucks, if you buy there off the shelf dished boost pistons, you are only in it for around 600.

Sears

That sucks BOS. <img border="0" title="" alt="[Frown]" src="gr_sad.gif" /> Good excuse for a low compression motor built for boost now eh? <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

Stock 6.0L heads, diamond boost pistons, stock rods, ARP rod bolts, and new bearings would be what I would do on a budget.

Justin

VINCE

iTrader: (1)

Yep, that really sucks..

BIGBOS

Whats the C/R on the off the shelf boost pistons?

Anyone know?

JF WS6

Bos,

Saw your car on Saturday. I'd think if you didn't damage your bottom end you might be able to get away w/ a set of stock CR 6.0 heads?

I think the dished Diamond's are supposed to be around 9.5 CR. Would probably be lower with the larger chamber LS1 heads. You'd really be able to crank up the boost with those.

Good luck w/ your Hawk.

LS1derfull

BigBos, have you considered keeping hi compression and running boost anyway? The more compression the less boost motor will be able to accept. This way driveability is good in non boost driving and full throttle out put shoulkd be great also. Yes this will require proper timing and tuning to work good but why not run it like this? Anyone try this?

BIGBOS

Well these heads are anywhere from 10.7:1 compression to 11:1 compression which is high...

So...

If I did go with low compression pistons, how low (C/R wise with the piston) would I have to go to get at a safe level, if I can't sell the heads, this is what I'm doing..

I8COBRA

iTrader: (56)

I'd think you should be safe with 10.0 compression, thats what Jim is running now with the 9lb pulley. Anything under 10 is extra insurance I'd say. Personally, for a daily driver and something that I wouldnt want to rebuild anytime soon I'd go 9.5 at most.

NoGo

iTrader: (2)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by LS1derfull:
<strong> BigBos, have you considered keeping hi compression and running boost anyway? The more compression the less boost motor will be able to accept. This way driveability is good in non boost driving and full throttle out put shoulkd be great also. Yes this will require proper timing and tuning to work good but why not run it like this? Anyone try this? </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">11:1 is a pretty high bench mark to start with boost. He would have to keep the boost so low that it would make FI negligable

3 psi = 13.0
4 psi = 14.0
6 psi = 15.5

Now, if he was building an all-out race motor, then I would agree to keep the compression high. But unless he has a 110 octane pump in his backyard.....

Just my .02

NoGo

iTrader: (2)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by BIGBOS:
<strong> Well these heads are anywhere from 10.7:1 compression to 11:1 compression which is high...

So...

If I did go with low compression pistons, how low (C/R wise with the piston) would I have to go to get at a safe level, if I can't sell the heads, this is what I'm doing.. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">You are going to have to run at least a 15 cc dish piston to bring the compression down to 9.5. Here are some dish sizes to get you started.

10cc = 10:1
12cc = 9.7:1
14cc = 9.5:1 (minumum)
16cc = 9.3:1
18cc = 9.1:1

These are all for a stock motor with 61 CC heads.

Good Luck,
Kevin

BIGBOS

Isn't the stock chamber on a 5.7L head 67CC's?

NoGo

iTrader: (2)

Right around 67 cc.

The above numbers are for your engine with the milled heads that you have on it, 61.6 cc.

BIGBOS

Ah, ok, thanks.. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

JimmyKash

sell your heads, buy some replacements, do minor port work in the chamber and the bowl, slap them on.

cheapest and fastest solution in my head anyway

AP-Engineering

BIGBOS - I can get you pistons for less than $1000.00.

Custom flat tops with pins - $727.00 for the set
Custom domes with pins - $777.00 for the set
Custom dish with pins - $757.00 for the set

The prices above are with the good H13 tool steel wrist pins also.

Let me know if there is anything I can do for you.

Thanks,
Chris Gelineau
Diamond Pistons
877-552-2112 toll free