Boosted lt1, high compression and timing

[anniversaryss]

I'm have 97 LT1 with a D1SC and twin intercoolers.
I'm currently running 11 to 1 compression and 13 psi.
24x ignition
The motor has forged internals. Wasnt originally intended to be boosted but here we are.
It's also set up to run e85. It has the sensor to flex.
I'm currently running on 93 and running e85 soon after.
My questions is mostly about timing with high compression.
I understand that there are tons of variables, I'm just looking for a good refence.
That being said what would I expect to see in as far as timing on 93? I'm currently at 14?.
What about timing on e85?
The flex table is currently set to add 6?.

I appreciate any and all help.
Thank you

[Ben Charles]

9.1 CR on my setup at 18lbs on e50 and high I’m about 30 degrees.. 93 I’m around 24…

At 11.1 CR I would say 93 around 17-19 degrees and 24 on e85 be about right on that setup

[Alvin]

Typically very deep into the 20's if not low 30's for most GEN 2 LT1 boosted applications. Remember NA some will take up to 42 degrees.

[Bandit_Z28]

I'm in the low 11's on compression too. I've thought about going turbo or supercharger as well. Are you running a p59 ecm?

[anniversaryss]

Thank you guys. I figured I'd go up a few degrees at a time. Watch knock. I was thinking 20 degrees was the point of no return with the compression I have.
So that being said if I'm still good at 20 degrees which is 6 degree difference is that good for roughly 100 hp? I've read people making 25hp/2 degrees.
I figured timing is what's keeping me low on power for 93. 14 degrees didnt seem right to me from my research.

[anniversaryss]

I'm in the low 11's on compression too. I've thought about going turbo or supercharger as well. Are you running a p59 ecm?

I'm running a P01 with the 2 bar flex OS from an 02 Tahoe

[07GTS]

work out your dynamic compression based on your engine and camshaft is best, u can run alot of static compression if the IVC is later

[DrLoch]

My setup is closer to Ben Charles, Camshaft is a older comp 224/236, my compression ratio is 8.7. I'm around 29 with boost at 17 non intercooled with meth injection ahead of the TB and at inlet of ProCharger.

[anniversaryss]

10 online calculators gave me roughly 9.95:1 dynamic compression and 9.8ish at my elevation which is only 600 foot.
Now im not terribly understanding what to do with that. Lol

[DrLoch]

Are your knock sensors telling you anything? What are your IAT's?

[Alvin]

Just be very careful on the knock sensors. All of the torquehead and EFIconnection swap cars iv'e done have had knock sensors that would not report. I've heard on another post that a 350 SBC express van knock sensors would get them working. But I don't have personal experience.

[anniversaryss]

I've seen knock with my cammed setup. Although I do share the concern of not detecting knock correctly as I've seen it before. My IAT on 93 were above 140. I was hoping that would change in open fresh cool air l.

[anniversaryss]

Just be very careful on the knock sensors. All of the torquehead and EFIconnection swap cars iv'e done have had knock sensors that would not report. I've heard on another post that a 350 SBC express van knock sensors would get them working. But I don't have personal experience.

I've seen knock on my cammed car but I'll check out the van numbers. I believe my sensor sensitively was less than the van tho.


EDIT: checked my knock sensor settings vs the van setting and looks like I'm using the van settings already.

Checked against the ls1 setting the ls1 setting are def less sensitive than the van setting. Maybe bc if knock sensor location or block material idk. Or bc the Van's had cast ironheads?

Either way I'm not against making my sensors more sensitive to test them out

[Alvin]

I've seen knock on my cammed car but I'll check out the van numbers. I believe my sensor sensitively was less than the van tho.


EDIT: checked my knock sensor settings vs the van setting and looks like I'm using the van settings already.

Checked against the ls1 setting the ls1 setting are def less sensitive than the van setting. Maybe bc if knock sensor location or block material idk. Or bc the Van's had cast ironheads?

Either way I'm not against making my sensors more sensitive to test them out

This is more of a physical knock sensor difference rather than settings in the tune. From college I know that knock frequency (as in the sound it produces) depends on things like the speed of sound and bore size.. combustion chamber shape, mixture density.. etc . Your basically listening for that particular echo. I don't have any proof of this but I suspect knock sensors are tuned for picking up knock in the engine they are meant for.. Else they would pick up random noises etc.

I would expect a LSX knock sensor would work reasonably close between LSX engines but a SBC / LT1 is so different I don't know if that would be the case.

[anniversaryss]

This is more of a physical knock sensor difference rather than settings in the tune. From college I know that knock frequency (as in the sound it produces) depends on things like the speed of sound and bore size.. combustion chamber shape, mixture density.. etc . Your basically listening for that particular echo. I don't have any proof of this but I suspect knock sensors are tuned for picking up knock in the engine they are meant for.. Else they would pick up random noises etc.

I would expect a LSX knock sensor would work reasonably close between LSX engines but a SBC / LT1 is so different I don't know if that would be the case.

Ah ok I missed the part about the physical sensor. I read it as if you meant the tune.

I'll look into it

[Alvin]

Ah ok I missed the part about the physical sensor. I read it as if you meant the tune.

I'll look into it

Note.. I don't have proof of this or anything.. It's just in my experience EFIconnection and torquehead swaps seem to have consistently unreliable knock sensors

I've heard the SBC Express vans that used a 411 are good knock sensors to use.

[anniversaryss]

Note.. I don't have proof of this or anything.. It's just in my experience EFIconnection and torquehead swaps seem to have consistently unreliable knock sensors

I've heard the SBC Express vans that used a 411 are good knock sensors to use.

Its interesting you bring up torqhead. I talk to the owner all the time. The pre 96 kits from torqhead come with the Van sensors. So the knock sensor stuff is still up in the air for me. I guess I'll just have to see what happens. A little bit at a time.

[anniversaryss]

Note.. I don't have proof of this or anything.. It's just in my experience EFIconnection and torquehead swaps seem to have consistently unreliable knock sensors

I've heard the SBC Express vans that used a 411 are good knock sensors to use.

I did some digging and the knock sensor stuff is odd.

02 Express 5.0 uses KS2
97 LT1 (mine) KS2
02 Express 5.7 KS7

I compared the 02 5.0 (KS2) to the 02 5.7 (KS7) with efi live. Efi has sensor sensitivity settings as well. Either way both tuned were EXACTLY the same for knock sensitivity settings . So its possible to say the KS2/KS7 sensors should interchange.

O well. Its been a while. I haven't had a chance to get out. I'm going to try 16 degrees and work from there.

[Alvin]

Have you actually seen the knock sensors report anything? I still haven't had a eficonnection or torquehead swap report any knock at all.

[Fast4.7]

Have you actually seen the knock sensors report anything? I still haven't had a eficonnection or torquehead swap report any knock at all.

My 24x L31 reported knock just fine. My 383 SBC runs on the L31 knock sensor calibration without any false knock as well and it has Rhoads V-Max lifters, 1.7 full roller rockers, hardened pushrods and guide plates and forged pistons with more piston to bore clearence.