My mods are in my sig. I'm running Patriot stage 2 heads 64cc. I can mill the heads and/or use a thinner gasket. What cc can I go down to and still be able to run the 93 octane gas? How much more horsepower and torque will I pick up? I'm probably at 10:5/1 at the moment give or take. The current head gaskets are stock LS6 gaskets. Id like to add around 30-40 hp and torque. Possible??



Thanks,


Matt

 

Use the search dude this topic has been thrashed out many times recently. Its down to your dcr, temps, quench etc.

 

Searched, but found nothing

 

rule of thumb is 2-3% increase in power for a full point in compression increase, (ie: going from 10:1 to 11:1); so if you are making 400 crank hp at 10:1 and go to 11:1 you might see 8-12hp. again this is a rule of thumb only.

 

I am at 11 to 1 compression and have had no issues at all with Michigan fuels. I liked how she ran before they switched over to the Summer Blend. This fall the fuel changes back again. I only use Mobil 93 or BP's Amoco Ultimate 93. Runs bad on Sunoco 94 or 93. Horrible gas mileage, and reduced performance in my opinion.

 

What if I went to 59 cc heads?

 

It is mostly relative to DCR, not as much SCR.
Tight quench helps fight detonation.

I run 11.7x with 8.6x DCR on 94 with no issues. .040 quench and TR6 plugs (1 step colder gapped .040)
I run 26* advance timing, I saw no increase in power by going higher.

 

i did run 11:7 scr,around 9:0 dcr on 93 with gm mls gaskets but that was in the spring.i will have 11:9 scr now but i'm going to a bigger cam so dcr will be around 8:7 or so but dcr is where it's at.of course different motor combos will act differently also.

 

Like some of the others said, its DCR that matters, not SCR.

Bigger cube motors take a bigger cam which usually cuts down DCR. Thats why you can see strokers running 12:1 on pump gas.

While you may not pick up a ton of HP, the low end torque will definately be be bolstered a bit. It will really help eliminate any mushiness from down low.

 

Im running 11:1 here in hot texas on 93 just fine! New dyno numbers coming soon. if it matters!

 

I live in MI. also. I don't use Sunoco either. It has 10% alcohol. Less power and worst fuel mileage.

 

I'm in the same boat and doing the same as you. I'm looking to pick up a little bit of low end throttle response / power. I've decided to take a three step approach to this:

1. I started to do custom, part throttle tuning since previously I had just WOT / dyno mailorder tuning. So I did notice a nice performance and drivability increase.

2. I have a couple header bolts stripped, so I'm pulling both heads and having them helicoiled, while they are off, I'm swapping the stock gaskets (0.056") with a thinner (0.040") cometic and increasing my dynamic compression, and decreasing my quench. This has been reported to help increase low end torque and actually reduce the tendency to detonate.

3. I'm still running a stock pulley, so I'll swap over to at least an underdrive pulley, and maybe a lighter one as well.

I figure doing these three things won't cost me too much money, since I can do the labor myself, and none of it will impact drivability but rather add more power where I drive the most, below 3500 rpm.

 

Wow thats complete BS! Many cars come from the factory with similar SCR. FROM THE FACTORY!

 

Another thread with all of you luck A**holes that get 93 octane!!!!!! Down with California!!!!!!! 91 blows.

 

Well, I think the point that is trying to be made is that you can't make a general statement about what a car can/can't run based on one particular setup that is having issues. The bottom line is that DCR, heat, quench, cam specs, etc all play a role in what you can run without getting detonation. Right now, I'm running 11.6:1 SCR with a DCR of around 8.0:1, a quench of .032, and a lazy *** cam that bleeds off a good amount of compression, and I'm getting knock retard from possible detonation on 93 pump gas. Many people run higher SCR and DCR on 93 octane with no issues at all, so it's a case by case basis.

 

It really depends on the whole combination as to what octane you can/cannot run on.

FWIW. On my 408... with 11.3:1 SCR, my car will run on 87 octane with no knock retard anywhere with timing at 38ish when cruising and 27-28 at WOT. This is due entirely to the 248/254 114lsa cam having a TON of overlap and bleeding off craploads of compression (DCR is down at about 7.7:1) Car still makes 475+ through exhaust on 87 octane gas... in the Texas summer heat/humidity.

 

Actually I thought I read where Brian Tooley did a bunch of testing on heads and found that a stock set of heads that had been milled to produce a full point higher compression ratio actually made as much power as a high end ported set of heads that were at 10.1:1 compression ratio. I'll find the post later, but with all his testing, a higher compression always yeilded better results while using the same cam, headers, intake manifold etc.

I wouldn't be so quick to discount the benefits of a higher dcr/scr with our style heads. I guess that's why some guys have better results than others based on how much they mill their heads and how tight they get their quench.

 

+1, higher compression will generally always yield better results. The name of the game is to run as much SCR/DCR/timing as you can get away with on the gas you want to run.

 

Ahhhh....

When you are wrong result to name calling... very mature.


I never said your car was not detonating... I said nothing about you or your car. Please re-read my response.

It is funny you mention DCR now... when you said nothing about it in your first response. Sounds like you made a "oh ****, I made a fool of my self, let me search the forums so I can actually figure out what I am talking about."

You said "The max you can go is 11.3:1 on 93 octane gas." Which is WRONG!

How can you say that is an opinion... You stated the above as a fact... which it is not.

I run 12.33:1 SCR and 8.75:1 DCR on 93 octane with OUT detenation...

So isn't that prrof you are wrong? As already said DCR plays a bigger role than SCR

So your statment of "The max you can go is 11.3:1 on 93 octane gas." IS BS!

And everyone on these forums will back me up on that.