Realistically, how reliable are turbos on LS1s?

On my long search for an LS1, I have looked at many mods. Heads and Cam is a good N/A setup. Prochargers look sweet, too. However, I am pretty clueless about turbocharged V8s. Since the LS1 is a pretty high compression motor, I'm guessing you can't run that much boost. Am i correct? Would 8 psi be pushing it? How much could you piece a turbocharger system together for including installation and proper tuning, and what would you expect to run in the quarter mile? What could you safely boost it up to? How reliable is the system; will it be dead reliable or will parts break left and right? Thank-you! :)

I just had the turbolocity twin turbo set up installed on my 2001 z28 and so far the cars reliability hasn't been affected. Granted it has only been about a 1000 miles since I have had the car back, however, I am running 7.5 lbs of boost on a completely stock motor with out any issues. If you do turbos make sure you have a reliable shop do the tuning that knows turbo systems. As far as cost that will vary to what you want to do and if you can do any of the fabrication yourself.

check out ls1tech and go to the FI sec.some of those guys are running sick times with turbos.some are on stock bottom end and some are even on stock heads and cam and making serious power.

The ls1 shortblock is pretty strong. Many peole have taken it to 600rwhp with a blower,juice, or a big heads and cam setup(not 600rwhp for H/C) but it does a hell of a lot better than the lt1's. You can find kits out for the ls1, pieceing it together is going to be hard if you have never built a tubro kit. The 1/4 time would be a second less if you running 6-7psi. If you kept at low boost levels for everyday driving and ran 100+ octane at the track on 10psi you could have you fun and a daily driver. I think that would last a while if you could be nice to it.

I think the record is 9.86 at around 137 for a forced induction stock bottom end LS1. The guy changed the heads to 6 litre heads though to lower the compression. The strength is there, you just need to keep it out of detonation and you'll be fine.


If you're pretty clueless about forced induction V8s like you said you were I would recommend buying a kit as opposed to attempting to fabricate your own kit as there are a few different kits out there on the market.

With respect to forced induction, etc. I don't see any reason to think the LS1 bottom end is any stronger, or strong enough, etc. The piston is the big weak point, and I believe the LS1 piston even has a smaller ring land than the lt1, as well as still being a hypereutectic piston.

I really wouldn't do a FI kit without a rotating assembly built for it - but at a minimum make *sure* you can afford to do a rebuild.


Chris

Originally posted by Chris B
With respect to forced induction, etc. I don't see any reason to think the LS1 bottom end is any stronger, or strong enough, etc. The piston is the big weak point, and I believe the LS1 piston even has a smaller ring land than the lt1, as well as still being a hypereutectic piston.

I really wouldn't do a FI kit without a rotating assembly built for it - but at a minimum make *sure* you can afford to do a rebuild.


Chris

It does have 6 bolt mains, and a half a point less compression than an LT1, and it being all aluminum may make it easier to run more boost in the stock motor because it sinks heat away better allowing less chance for detonation. just a thought.

Bill

Originally posted by Chris B
With respect to forced induction, etc. I don't see any reason to think the LS1 bottom end is any stronger, or strong enough, etc. The piston is the big weak point, and I believe the LS1 piston even has a smaller ring land than the lt1, as well as still being a hypereutectic piston.

I really wouldn't do a FI kit without a rotating assembly built for it - but at a minimum make *sure* you can afford to do a rebuild.


Chris

You mean the fact that people have already pushed 650rwhp+ and 9's on the stock engine isn't reason enough? What exactly do you want? Ask an LT1 guy how long his engine will go on 9psi.

Originally posted by Mikael
You mean the fact that people have already pushed 650rwhp+ and 9's on the stock engine isn't reason enough? What exactly do you want? Ask an LT1 guy how long his engine will go on 9psi.


i like how ive read over and over ls1s fall apart under high boost with stock internals when that just isnt the case.yes theres limitations and you need a good tune but they make awesome power reliably.

It does have 6 bolt mains, and a half a point less compression than an LT1, and it being all aluminum may make it easier to run more boost in the stock motor because it sinks heat away better allowing less chance for detonation. just a thought.


True it has six bolt mains, but I don't think that is a weak point (as was pointed out). In a FI setup it's basically the pistons that die (crack a ring land). And yes, the compression ratio is just under half a point different, which helps some - but I don't think that it makes a huge difference. Also I think the thinner ring land counteracts any of that advantage

You mean the fact that people have already pushed 650rwhp+ and 9's on the stock engine isn't reason enough? What exactly do you want? Ask an LT1 guy how long his engine will go on 9psi.

I did just under 600rwhp on nitrous on my stock bottom end (587 was the best value) and it didn't blow up either (LT1). That said, you can find anecdotal evidence to support almost anything. There is only one stock bottom end FI car I am aware of making the power/times you mention, so I wouldn't think that really proves anything. There are also quite a few people who had their card die under boost also (or lift the heads, so it can go both ways).


I think we can agree that the pistons are the weak part of the stock bottom end with respect to a FI setup, correct? So given that the ls1 pistons are the same hypereutectic construction, and actually have a thinner ring land, I am wondering where this extra strength comes from?

Again, not trying to "disparage" any motor, etc - just trying to be realistic. FI on a stock bottom end is just a matter of time until it blows up (if you are driving it with any kind of regularity (mine's a daily driver)) - now if you just drive it for 10 miles on the weekends things are a little different.


Chris

Originally posted by Chris B
With respect to forced induction, etc. I don't see any reason to think the LS1 bottom end is any stronger, or strong enough, etc. The piston is the big weak point, and I believe the LS1 piston even has a smaller ring land than the lt1, as well as still being a hypereutectic piston.

I really wouldn't do a FI kit without a rotating assembly built for it - but at a minimum make *sure* you can afford to do a rebuild.


Chris

I agree with Chris. The bottom line is that forged pistons are recommended with any kind of forced induction. And that includes the accompanying rings and gaps.
When the lt1 supercharging got big, this was also the argument.
I ran 9 pounds of boost and it was fun for awhile. It eventually broke though. It never ran good with that high compression anyway. The lower compression helped a lot.
So if you do FI on a stock motor which was never engineered for FI in the first place, there is a risk factor involved. :)

I have the STS kit at 5psi, 7psi soon :), and has been running strong with no probs. I do agree with everyone that it is only a matter of time if you are up in that 7+psi range on a stock bottom end.
Reliable if you are happy with a moderate psi.

Originally posted by Whistler
I think the record is 9.86 at around 137 for a forced induction stock bottom end LS1. The guy changed the heads to 6 litre heads though to lower the compression. The strength is there, you just need to keep it out of detonation and you'll be fine.

Seen it on the dyno, at the track... Stock bottom end, 10 psi, 590rwhp/590rwtq, TT CE TA (http://www.dieseldigital.net/media/cofba_drags101703/imagepages/image107.html)

:bow:

The reasons the ls1's can take the boost and not have a piston failure is because the ringlands are much stronger. The motor justs flat out holds up better. Look at the numbers, any stock bottom end lt1 with 6-8psi will last for a while if you treat it nice, run high octane, and always keep a watchful eye on you a/f ratio and detention. It will be at 400-450rwhp. The ls1's run 10lbs and throw down numbers in the 500's that is a big difference. Even the hypercrap pistons and rods are better than the lt1's. Not to mention the heads

the ringlands are much stronger

Based on what? The ringlands are actually thinner than on LT1's.


Chris

you can make either one last even with higher boost...boost doesn't kill pistons/rings, detonation does. If you wanted you could possibly run 12-14psi on a stock bottom end, but you would need good race gas, retarded timing, and probably alky injection to do it, and it would have to be WELL tuned to not blow it up.

There are some guys in GN's running 30+psi pressures on stock style cast pistons...they aren't hypereutectic, but they aren't forged either...they tune the CRAP out of them.

my stock motor has survived since this past summer just fine. my qmp kit has been super.

I guess this turned into another turbo LT1 vs turbo LS1 but FWIW...

Perhaps the reason an LS1 holds up better at higher boost/HP level is a combination of these things

1 Lower compression
2 Better PCM with dual central mounted knock sensors keeps a better handle on preignition, which is the reaper for either of these engines.
3 Better flowing heads which skews the boost comparision. An LT1 with 7 lbs of backpressure(boost) in the intake isn't getting the same CFM flowing through it as an LS1 with 7 lbs.

All that said if you're going to FI the LS1 with a stock bottom end the best thing you can do is pick up a set of the cheap and readily available 6 litre aluminum truck heads. These combined with a little thicker head gasket will get you close to 9:1 and flow even better than the regular 5.7 heads.

Originally posted by Whistler
These combined with a little thicker head gasket will get you close to 9:1 and flow even better than the regular 5.7 heads.


FWIW, compression should never be dropped by use of a thicker head gasket.

In theory no, but lots of people do it and it works.

I ran 15 PSI and over 600 RWHP for 2 years on a stock ZZ3 350 bottom end with big chamber AFRs and a double thickness head gasket to get the compression lower.

You can get cometic MLS gaskets for LS1 in just about any thickness you want. I wouldn't do too thick, say over .070