Okay. Simple question for the pro engine builders. What is the highest compression possible in a LS6 with no worries of type of fuel. This is not about running on street gas. If you were to start with a LS6 block what would you do to the components to get the highest possible compression?

 

Mid-high 11s should be ok with 93 pump gas, anything past that and youre pushing it.

 

Dome pistons, larger stroke crank, small chamber heads.

 

I should clarify. It could be any gas; methanol, alcohol, nitro, this doesn't matter.

What I'm looking for is the physical limits of this motor for high compression.

So if it's longer stroke, smaller cc heads, domed pistons give me the specifics. What stroke crank, make and size of heads, make and size of pistons. I'm looking for the combination of these parts, and have them have the clearance and ability to have a long duration cam with high lift, say .500 to .600 lift. With all this what would I end up with for my compression, making it as high as physically possible.

Hard question that you don't hear often.

Any experts with the answers?

 

I think you should read a little more...

Here is a CR calculator, have fun with it.. The fuels u stated are all different and run at different CR's for the most part.

http://www.csgnetwork.com/compcalc.html

 

Quick and easy one. 4.185 bore (requires sleeves) 4.125 stroke. (requires clearancing) with flat tops -.008 deck height, Stock C5R head (30 cc) .040 head gasket. = almost 26/1 cr ratio.
You just built a diesel! With a proper diesel conversion it might even run...
But not for long probably...
Bet you can order all this stuff tomorrow if you wanted...

But why do you ask?
What is the purpose of this thread?

You could acheive even higher ratios by milling the C5Rs or ordering special domed pistons but no one even thinks about that.
It's just silly...

 

One of my friends is running an ls1 with 14:1 compression on race gas....has been for years

 

for the ""best" burn you can run a slightly fished piston and have the head chambers welded up for a super small chamber....this will put the most force on the center of the pistons instead of out on the rings like a dome piston.


What is the point of your question? Just trying to find the ls1 breaking point?

 

I've seen 14:1 also on a full drag car with 317 heads.

 

Just doing some preliminary research on a engine rebuild. Thinking of approaching this from a different angle though.

What I've seen so far in my early research is that I could get a fuel to approach 120-125 octane by taking premium pump gas and adding pure methanol with an injection system before the intake manifold. Hypothetically this is easily within reach. So with this high octane fuel, as I understand it, I should be able to run somewhere between 15:1 and 16.5:1. I just was not sure if it was physically possible to get these high compression ratios with an LS6 and still have all of the components work together in harmony.

Really like the idea of getting 700+ HP from a NA engine and have the feel of a high compression motor. No turbo lag or heat sink issues that comes with forced air (not to mention the cost) or NOX bottles that do not last a whole day of lapping around a road course.

Also as a possible future benefit, the opportunity to switch to Hydrogen for fuel which runs best at high compression. This is more "out there in the future" and would be totally reliant on future fuel sources. So let's leave that one off the table for this discussion.

Interesting, isn't it?

 

I think the proper question should be, "what compression do i NEED for XXX amount of HP."

Compression isint everything. Nothing interesting about this question or build. and honestly it sounds kinda ignorant. building your engine around a desired compression ratio will get you nowhere. you dont need 16:1 compression to acheive 700hp, that can be done very easily with 11.5:1 in a 408 and a properly spec'd cam and a killer set of heads, all matched accordingly of course.

 

Now I would have no problem at all with this high compression IF you went with=
Forged crank
Forged pistons (slight dish)
H beam rods
I'd get the higher compression from a super small chamber head....weld the chambers up, them mill the chambers back to the desired cc...or as said above the CR5 heads have around a 30cc chamber to begin with.

Also since your talking so much higher pressures I'd go with an iron 6.0l (only 87lbs heavier than the aluminum one)

Third I'd ditch the ls style intake in favor of the Edelbrock proflo xt (like I run now), or ITB intake like the Harrop (if you have the $6000+ for it)

Fourth huge cam and spin the motor all the way up close to 9-10,000 rpms.

That's how I'd do it any way

 

You planning on using this motor in a trailer car or on the street?

Want 700+ reliable street power NA.
https://ls1tech.com/forums/generatio...ker-ready.html

You aversion to forced induction is short sighted...
Especially when meth is in the picture and "cost" is a factor.

What is your background?

Give us 100 words about your automotive experience.

 

48 hours, no reply...

Figures...

 

Sounds like a writing assignment......

 

I think he's a kid....

Probably used to it anyway!

 

You have got to be kidding me. Look, Techninja, I was upfront and direct with my question. I'm only looking for opinions from engine builders with the professional level of expertise to give a direct answer to a straight forward question. I do not want you to be trying to turn my thread into some personal attack on me or my intentions for my car. BTW, look at my car, it's right next to my username. And where is your car? Thought so. If you don't have something constructive to say, don't say it. Didn't your mommy teach you that? As far as who I respond to and how long that takes that's none of your F-ing business. I work for a living and that takes precedence over being on a forum. I get on here when I can, which is also none of your business. Grow up.

As for the rest of you that have responded in a mature fashion, I thank you for the input. It has got me looking in a direction that is showing promise of the possibilities of doing an engine with high HP through forged components, sleeved block, aggressive cam, good heads, and yes, high compression (15:1). The trick I see is controlling the pre-ignition through a separate fuel injector system dedicated to a water/methanol solution. This would have to be controlled by a computer that is using input from the engine sensors and a complete engine tune would be incorporated with this system. Still researching that part.

Just a reminder. This is very preliminary research and I'm exploring this as an option for a future rebuild. Thank you all once again for the input that adds to the exploration of a different way to achieve high performance in our cars.