LLT Max Boost

[MagnumForceGB]

What do you think the most boost the LLT can handle before it does an oil change in the middle of the road? I'm at 13 PSI on a cool day, thinking of going to 15 PSI now with Methanol as a secondary fuel.

[M0dnar]

Just out of curiosity what else have you done to strengthen the motor? I'm sitting at 11 PSI right now and I'm scared to go higher.

[HP Turbine]

Your effective compression ratio will be 23:1 Which is up there. I'm not sure how much methanol helps with that though.

[GretchenGotGrowl]

Here is a pretty handy calculator. Remember, this is static compression ratio, your dynamic ratio will depend on the timing of valve events and the actual volume of air in the cylinder at TDC. Different setups flow different amounts of air for a given PSI.

https://www.rbracing-rsr.com/compression.htm

On stock pistons and rods, I'd try to stay around 20:1 or lower for static compression ratio. It can probably handle more, but you will need to be spot on with the tune and make sure you have plenty of octane.

[MagnumForceGB]

Still stock internals.

Thanks for the info Gretchen, looks like I run 21 right now, 15 psi would put me at 22. Now that I have my methanol spraying the correct way I'm running around 25 degrees of timing at full boost, keep reading that you shouldn't increase timing with methanol but increase boost.

[JantzenOKC]

By that calculator I'm at 22 give or take a little.

[GretchenGotGrowl]

By the way, I don't really follow my own advice. I'm at about 23.5:1, but we did play with the valve timing a lot to keep the dynamic ratio down. I also have forged pistons and rods, so that helps, too.

[MagnumForceGB]

Originally Posted by GretchenGotGrowl

By the way, I don't really follow my own advice. I'm at about 23.5:1, but we did play with the valve timing a lot to keep the dynamic ratio down. I also have forged pistons and rods, so that helps, too.

I can also lower my shift RPM, I'm revving to 7200 right now, adding an extra psi. I just need more boost at 5000 RPM's, at 6 right now after a shift.

Do you know where I can find the stock cam specs? What degree the valves start opening at parked position. I know the duration is 220 degrees but nothing else.

[GretchenGotGrowl]

Originally Posted by MagnumForceGB

I can also lower my shift RPM, I'm revving to 7200 right now, adding an extra psi. I just need more boost at 5000 RPM's, at 6 right now after a shift.

Do you know where I can find the stock cam specs? What degree the valves start opening at parked position. I know the duration is 220 degrees but nothing else.

I'll have to look, but I think it is 21 degrees full advanced/retarded with no actuation. I'll try to find that tonight.

Edit
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Okay, I did a quick search and I'm seeing numbers between 20 and 22 degrees. At idle the intake is fully retarded and exhaust is fully advanced. One place said that when actuated (full oil pressure applied) the cams are at 0 degrees and another and another said the opposite. I really thing intake is fully retarded and exhaust is fully advanced until pressure is added, then you can move them toward zero with the actuators.

[djrasras]

Where is the best place to get forged rods and pistons for an LLT?

[hunterv6]

At 12 psi I am at 20.52:1


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[MagnumForceGB]

Originally Posted by GretchenGotGrowl

I'll have to look, but I think it is 21 degrees full advanced/retarded with no actuation. I'll try to find that tonight.

Edit
------------------------------
Okay, I did a quick search and I'm seeing numbers between 20 and 22 degrees. At idle the intake is fully retarded and exhaust is fully advanced. One place said that when actuated (full oil pressure applied) the cams are at 0 degrees and another and another said the opposite. I really thing intake is fully retarded and exhaust is fully advanced until pressure is added, then you can move them toward zero with the actuators.

Thank you, can visualize what I'm doing with the camshafts easier now. The tables say 7 degrees for intake, 15 for exhaust in park, but really don't say if it is opening or closing startstop.

Think I'm going to do 24 PSI of boost and a 200 shot of nitrous, take out every car within 20 miles of mine.

[MagnumForceGB]

Also, the tables in HP Tuners could also be degrees when the valves come unseated, so 21 degrees could be the point of contact with the 15 degrees being the unseat degrees. For exhaust side, 21 degrees before BDC and the 15 degrees that HP Tuners has is after BDC.

Going to get this LLT into the 11's, could do it now with a torque converter and drag radials, but want to try without. More boost will help and having a ton of overlap on the cam timing will bleed off the excess boost but one problem is I'm running methanol, don't think that is a good idea.