OK, I've got an LS1 so don't flame me too bad. I asked this on the LS1 boards but the LS1 has only been out since 1997 and turbo info on them is pretty limited, so I thought I'd ask over here.
Right now I have a 1999 LS1 with a turbo technologies single turbo kit. The turbo is a T66. My goal is, and has always been, 450 RWHP. Right now I managed that with 5.5 psi and a tune by yours truly with LS1 edit. I have 24 degree's of timing at WOT.
If I back the timing down to 18 degree's I need 7 psi to make my 450 RWHP.
Which way would be the least detrimental to engine life? Assuming all other things are equal (driving habits, track time, etc...).
Thanks guys! ;)
well first off the ls1 engine is not a turbo engine but people have done turbos and nitrous. and the ls1 engine is notorious for head gaskets and pushrods to break so i would get them stronger. i would stick with the 18 deg and 7 psi but i would beef up the bottom end to take the abouse for a long time because it will blow up, though the engine will hold up for a while our turbo blocks are alot thicker than non turbo engines for this purpose.
Take the timing - way more low end torque and that will also help spool the turbo faster.
To set the record straight on the LS1: The bottom end does have six bolt mains as opposed to the two bolts of a Buick (it could use some forged pistons, though,). People bend pushrods because they float the valves with stock cam and valvesprings. Head gaskets have the same life on a Buick as an LS1 - if you keep the knock down you will be fine. Just for the record, how much boost does it take to make 450 RWHP on a Buick? I guess that tells you which motor breathes better (boost is a measure of restriction, not air flow).
For the record I have one of each.
-Geoff
Thanks guys, keep em' coming. ;)
You find two different Buick Camps when it comes to Boost/Timing.
Camp 1 - Runs low timing 19º-21º and runs High Boost 26PSI+(they usually run smaller cams too)
Camp 2 - Runs Higher Timing usually around 26º and a little less boost. 20-25 PSI.
I have tried both and currently I run 26º timing and 22 PSI boost (basically the same turbo TE-66)and made just shy of 500 RWHP.
Geoff to answer your question it doesn't take any boost to make 450 RWHP in a Buick. Well in a 455 Buick that is. It is not a fair comparision considering the LS1 has an extra 2 cyclinders and a lot more displacement. While boost is not a measure of air flow nor is it really a measure of restriction either. It is a measure of the unused air that the turbo produces. In other words the airflow that 20 PSI boost from a 66 produces on a stock headed car with weak valve springs will be a lot less than the same 20 PSI boost on a car with GN1R AL heads with big valves.
I am sure this makes everything clear as mud Josh, but I think you will find people running both ways. The best way is whichever way makes the most horsepower with the least amount of detonation. Doesn't matter if you make the 450 with boost or timing, it's the detonation that beats the bearings to death and sends headgaskets out the sides of the head.
HTH
Sully
Thanks for the input. In my case the best is not which will make the most power, I can meet my power goals with either combination. I am mostly wondering if one way is easier on the bottom end. I guess less timing would be because the propensity for detonation is be less, but I dunno.
Thanks again! ;)
It seems to me that if you are making 450HP both ways, without detonation, that the force, either way, through the crank must be the same. As far as I know, the bottom end on the LS6 is exactly the same. The bottom end is not your problem! Take Steve and Geoff's advice. It is right on! Read the current GM Hi-Tech Performance about a rev kit for the LS1. That's your weak spot.
I don't really have a desire to rev the motor past about 5,500. RPM breaks parts. The wear is literally exponential as the RPM's climb. The rev kit in GMHTP is really cool, but I think pertains more to an NA motor that has to rev to the moon to make its power. As far as the bottom end goes, my rod bolts will prolly go first. The 6 bolt mains do a great job of keeping the crank in one place, but the rods and pistons attached to it could use some work for someone who plans to run FI.
This is my driver so reliability, not extreme power, is what I am looking for. I.e, the most reliable way to make 450 RWHP.
I would of went with a good heads and cam combo, but I live about 5,000 ft. above sea level. To achieve anything near 450 RWHP (uncorrected) turbo is the only way to fly.
So the concensus is to pull some timing and run a bit more boost?
Here's an educational link (IMO anyway):
http://www.kb-silvolite.com/page14.htm
On the surface you might think that this page is not worth much to us, since it is targeted specifically to nitrous engines, but I think that the cylinder pressure and ignition advance discussion is directly applicable to a forced induction engine.
John