~11.5CR & ~8.5DCR running on 87*
~11.5CR & ~8.5DCR running on 87* Ok, I'm a little confused here because everything I've read and been told was this combo should not be able to run on reg 87*.
Here is my engine setup;
05' LQ9 (ARP mains & Katech Rods)
Patriot lvl 1 243's (64CC)
Cometic .040" gaskets
TR230/224
Exhaust system is completly stock
I ran all the numbers and it came out to about 11.5 CR and about 8.5 DCR. For the longest time I've been running on 93* without a problem but wanted to see how bad 87* was and to my surprise it ran just fine, maybe even a little smoother.
The most I could pull from 93* was about 25* timing. Right now I'm at 22* running 87* with no detonation.
Here is my engine setup;
05' LQ9 (ARP mains & Katech Rods)
Patriot lvl 1 243's (64CC)
Cometic .040" gaskets
TR230/224
Exhaust system is completly stock
I ran all the numbers and it came out to about 11.5 CR and about 8.5 DCR. For the longest time I've been running on 93* without a problem but wanted to see how bad 87* was and to my surprise it ran just fine, maybe even a little smoother.
The most I could pull from 93* was about 25* timing. Right now I'm at 22* running 87* with no detonation.
I'm far from an expert but I thought the 64cc heads only gave you 10.8-11.0 SCR on an LS1 motor...not sure how different the LQ9's are but I think they're the same. That would explain your ability to run 87, since you'd be closer to 8:1 DCR.
Originally Posted by Billdog350
I'm far from an expert but I thought the 64cc heads only gave you 10.8-11.0 SCR on an LS1 motor...not sure how different the LQ9's are but I think they're the same. That would explain your ability to run 87, since you'd be closer to 8:1 DCR.
Also the DCR is changed now do to the cam, which running a DCR calculator I got 8.5.
This is possible where I made a mistake. I was told the deck height on a LQ9 should be -.007-.008 which put the DCR at 8.5. But if I put in a positive .007 it will come out to 8.1 DCR.
Last edited by Zick; Nov 1, 2006 at 05:28 PM.
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bigger cubes tend to be able to handle higher compression. Partially this is due to the lower DCR of a bigger cam, but i feel it goes further than that. More cubes just take more compression.
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Originally Posted by PREDATOR-Z
Try to bump up the timing to what it was on 93 Octane and see what happens 
You lowered octane and lowered advance, so why wouldn't it work?
You lowered octane and lowered advance, so why wouldn't it work?
I understand that I lowered the octane and lowered the timing(only by 3*). What I'd like to know is whether or not my figures are wrong or why is everyone saying that you have to run at least 93 octane if your DCR is 8.5+?
Originally Posted by allngn_c5
Did you do this so you wouldn't have to pay for premium fuel?? Anyways as long as you are happy that's all that matters.
