dailydriver

What does the average set of 16 gauge, 304 stainless long tubes weigh, vs. the stock iron manifolds and down pipes??

Dropping weight off of the nose would be my only motivation for using LTs, but then having to de-tune the car/use a very weak cam to meet NASA power level requirements.

redtan

iTrader: (5)

[QUOTE]IMO a stock cam with LTs would be my choice over an aftermarket cam and stock manifolds.

Less weight, more torque, softer lobes, less engine heat (if you have them coated).

Shorties are a good way to drop weight (even over LTs) but not add much power in order to stay within a certain power limit.

Steve91T

But LT's and stock cam won't make enough power. Do you mean use the LS6 cam?

Steve91T

So let's say I do stick with stock manifolds, what cam should be used?

redtan

iTrader: (5)

With LT headers either cam will get you there.

Remember the LS6 came with 400hp at the flywheel stock, which is like 340rwhp already. With the LS1 cam you will needs LTs, with the LS6 cam you probably won't.

Steve91T

Did some digging. The iron manifolds weight 28-31 lbs combined. Add some weight for the Y pipe. I have no idea what LT's weight, but it can't be a huge difference.

Redtan, if a stock ls6 makes 340 to the ground stock, then how is my LS1 with LS1 heads and an ls6 cam going to make more power than that? I won't have the ls6 heads which make more power than the ls1 heads.

This is why I'm getting confused. From my searching, the 01-02 ls1's came with an ls6 intake. They had better flowing exhaust manifolds than the 98-00's. The cam changed as well. So, if I pick up an 01-02 ls1, I will have decent flowing manifolds, an ls6 intake, and that's it. I can add an ls6 cam but I won't have ls6 heads. So my power to the ground will be less than a true ls6, right?

dailydriver

[QUOTE=redtan;19198964]
TOTALLY AGREE!!

But, decent shorties for our cars (in even 400 series stainless ) are getting harder and harder to find, as many companies which used to make them have now stopped.

Of course, they are a dime a dozen for the 5th gen LS3s/L99s.

dailydriver

I'm also going to guess that given the insane demand for (and the TOP DOLLAR$$ they are getting for) the LS6 intakes, that most selling a latter, '01-'02 LS1 take the intake off an sell it on it's own.

Probably the same even for a used LS6 as well.

redtan

iTrader: (5)

I was talking with LT headers on the LS1 combo. Those are rated at around 350 flywheel so with the LS6 cam and headers it will probably make just a bit more than the stock LS6. I mean it's all real close, but at least you have few different options of getting there with a 5.7 based shortblock and then all the combinations you can make out of the OEM top end of those engines.

I'd say your choice is between the true LS6 with some shorties/manifolds or the LS1 with LS6 intake, cam and LTs. Tuning will be the determining factor to get you to the final number that you need to make for your class. Just in the tune alone you can change some 10-15rwhp, so that is your buffer.

Me personally I would do the true LS6 if you can afford it. The block is slightly stronger and the LS6 heads have the lighter valves and are better at oil control. Or do the LS1 block with the LS6 heads so you still get those benefits.

Steve91T

I agree a true LS6 would be ideal but I doubt I'll be able to find/afford one. Plus I like the idea of running an LS1 with a cam because if I blow it up, it'll be cheaper to replace.


The more I think about it, the more I like the idea of running 01-02 manifolds. I'll try to find an 01-02 LS1 which should already have an LS6 intake, and use some sort of cam that's a little more aggressive than the LS6 cam.

If I use stock manifolds, I'll be able to use a stock Y pipe that uses oval piping for ground clearance. I will probably have the stock cats cut out and have high flow cats welded in (still need to see if that's worth it). Then I can use the stock mid pipe, and even the over the axle section. After that, I'll have the rest cut off and my straight through Borla muffler welded on, exiting straight out the right side under the rear bumper.

I already have the over the axle section off my parts car, I just need the Y pipe. I'd bet I could pick one up for next to nothing from the same place that I'm getting my ls1 from (hawksthirdgen).

Since the manifolds are the limiting factor, the rest of the exhaust (except for muffler and possibly cats) will be just fine. It'll be dirt cheap and will give me the ground clearance I need.

I just need to talk to someone who really knows their stuff and have them pick out a cam that'll do what I need it to do.

dailydriver

Yes, true, as there are very few on here who understand the power needs/demands of road racing, and are just used to suggesting cams which will make max peak dyno power for the top end of the 1/4 mile.

Steve91T

Ha. Yeah I that came out wrong.

In my defense I have asked a couple of times what came to use with stock manifolds.

Martin Smallwood

iTrader: (2)

The short pipes/tubes and horrendous collectors on a factory manifold metaphorically (not literally) suck. They do not scavenge until very very high RPM's whereas your average LS engine long tube header starts to scavenge around 2000-2500rpm depending on cam profile.

You will make more bottom end and mid-range torque with a stock cam and long tubes than you will with factory manifolds and an aftermarket camshaft.

Personally I'd do the long tubes and then add a small aftermarket camshaft to really benefit from the scavenging effects of the long tube headers, but it might put you past your needed power/weight ratio.

Steve91T

Thanks for the reply. I'd really like to try to use stock manifolds if I can. My car is pretty low. The frame rails are just under 4" to the ground. I'm afraid if I use LT's, I won't even be able to get it on and off a trailer. I had LT's on my old LT1 back when the car sat higher and they were a pain in the ***. I had to use blocks to get it on the trailer and I absolutely couldn't get anywhere near a speed bump. Plus it will be considerably cheaper to use a stock exhaust.

As much as I'd like to maximize my power under the curve, I'm not sure it's worth the headache of having no ground clearance.

I can't overshoot my power to weight. If I do, it'll bump me to TT2, requiring me to have like 430 rwhp.

So what do you think? LS6 cam? GM Hot cam?

gagliano7

How about some Ls7 manifolds? I have read they flow the best out of the stock ones.

MuhThugga

LS7 manifolds are a good middle ground so long as they fit the chassis.

Steve91T

I think I remember reading they don't fit.

DavidBoren

Shorty or mid-length headers do not have the same ground clearance issues. Even the tubular LS9 manifolds would be better than factory cast manifolds. LS7 manifolds require extra parts, like whatever the oval-to-round elbow is called.

Any sort real exhaust will be beneficial. Probably more beneficial than a custom cam with a shitty exhaust. An LS6 cam, shorty headers, and true duals is probably all you need to achieve your goals. And it will have a better, more useful powerband than a custom cam trying to breath through cast manifolds, a Y-pipe, and single exhaust.

dailydriver

Will the LS9 manifolds even fit, because IF they do, then ALL of those LS3/L99 5th gen shorties will fit as well.

Martin Smallwood

iTrader: (2)

I wouldn't use any camshaft with stock manifolds, or shorties that had more than -6 degrees of overlap@.050 on a LS1 engine. Any more than this will create a very large loss in torque under 3500-4000rpm due to the manifolds and shorty headers inability to scavenge spent exhaust gasses and pull fresh intake charge into the cylinder during the overlap event. Thus the longer the overlap event is with these style exhaust systems, the more power will be lost until piston speed can start to create enough depression in the cylinder to bring the engine into tune.