C5 stock manifolds or shorty headers?

greg75vette

The Traffic Baron
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Jun 9, 2009
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Lindenhurst, LI, NY
Hey guys, I'm doing and LS1 swap in my '75 and I've been told C5 exhaust manifolds work really well for fit. However, I figure since they would fit well, so would shorty headers. Which leads to the question if shorty headers show any real benefit. I would be buying used either way.

So do the shorty headers offer any real performance benefit to the stock cast manifolds? There should be some improvement, but is it significant?
 
Why not get longtubes From the looks of it the LS conversion headers for F bodies may very well fit a C3.
 
The C5 shorties with the tubes stacked next to each other have a really good rep for high performance. I doubt they will work with the stock z-bar clutch setup but I think you are going to do the T-56 anyway, not a problem.
 
Why not get longtubes From the looks of it the LS conversion headers for F bodies may very well fit a C3.

I could actually get LT's that fit the swap perfectly, but they cost $750 coated and new. I'm not really looking to spend over $250 for two reasons: 1) this is a budget swap and the engine will be left stock for now 2) I plan on turbocharging the engine down the road so whatever headers I get now would most likely be useless in a few years.

Looks like I can get C5 stock mani's for under $100 and still get decent flow or possibly get better flow for some shorty's off ebay (I have a pair in mind) for about $250.
 
Would this be them, BBshark? TT, these are the ones I had in mind.

And yes, I'm running a hydraulic clutch. Oddly enough though, the stock C5 mani's do clear a Zbar setup with the swap plates I'm using.
 
Stock headers off a 99 and later Fbody are stainless, they're cheap, they fit and you can find them on junkyards. Try to get the first few inches of the stock Y-pipe with the two header flanges so you can weld your exhaust pipe to that pipe stub. Some Fbody models have the catalytic converter flanged to the header so you might have to cut the flange off the converter. Many take that stock stuff off and use off road Ypipes, you should be able to find two stock manifolds (headers) for under 50 bux
 
Stock headers off a 99 and later Fbody are stainless, they're cheap, they fit and you can find them on junkyards. Try to get the first few inches of the stock Y-pipe with the two header flanges so you can weld your exhaust pipe to that pipe stub. Some Fbody models have the catalytic converter flanged to the header so you might have to cut the flange off the converter. Many take that stock stuff off and use off road Ypipes, you should be able to find two stock manifolds (headers) for under 50 bux

I actually have those already. My LS1 is out of a '00 'bird. I was hoping to not use them because the C5 ones seem to line up better and get a little more performance. Also, the C5 mani's have both O2 bungs built in as where the Fbody's don't (passenger is after the exhaust flange). I believe they are also lacking EGR (or AIR). I haven't completely ruled the Fbody's out, but I didn't think they were stainless. They certainly don't look it, haha. I figure for a budget the C5 stock mani's or shorties will be a decent upgrade.
 
The Ebay manifilds look like a nice setup. If you can get those reasonably, that would be a steal.
 
I agree with Arthur, The F-body manifolds are stainless, 400 series (dirty stainless)... it turns brown and ugly but doesn't rust.
A handheld programmer like the Predator is all you need to turn off EGR and AIR....
The C5 manifolds might be a little better for performance but it's a Corvette part....means it's at least twice as expensive as a "normal" part.... I also doubt you really 'feel' the difference on a otherwise stock LS1.
Don't get me wrong, the stock LS1 is a great engine, I had a '99 Z28 for 7 years and the only thing I never complained about was the engine. I doubt you can tell the difference between the two manifolds, maybe it's measurable on the dyno but I doubt you feel the difference other than $200 more or less in your wallet.... now long tubes is a different story... Summit sells longtubes for LS1 conversions that I think are 304 stainless....
 
I had a look at the BB shorty headers on Ebay, these are great if you can get them at a reasonable price. Shipping is $40 which is quiet a bit considering the size and weight of these shorties (compare to four A-arms)...haha

If you want to install a supercharger and LTs in the future I'd try to go the cheap way for now...
 
I agree with Arthur, The F-body manifolds are stainless, 400 series (dirty stainless)... it turns brown and ugly but doesn't rust.
A handheld programmer like the Predator is all you need to turn off EGR and AIR....
The C5 manifolds might be a little better for performance but it's a Corvette part....means it's at least twice as expensive as a "normal" part.... I also doubt you really 'feel' the difference on a otherwise stock LS1.
Don't get me wrong, the stock LS1 is a great engine, I had a '99 Z28 for 7 years and the only thing I never complained about was the engine. I doubt you can tell the difference between the two manifolds, maybe it's measurable on the dyno but I doubt you feel the difference other than $200 more or less in your wallet.... now long tubes is a different story... Summit sells longtubes for LS1 conversions that I think are 304 stainless....

I agree about the corvette tax. I did find a pair on ebay that look good for $30 starting bid, $30 shipping. I figured I wouldn't get much more than the stock Fbody mani's in terms of performance (should have stated in the beginning I have them), but uses C5's would clean up the engine bay a bit not having unused bosses and block off plates. That what I was getting at with the EGR and AIR systems.

400 series stainless does explain the rust look. I think LT's are out of the question for now since I'm not sure what manifold's/headers I will need in the future. But you pretty much state that below.

I had a look at the BB shorty headers on Ebay, these are great if you can get them at a reasonable price. Shipping is $40 which is quiet a bit considering the size and weight of these shorties (compare to four A-arms)...haha

If you want to install a supercharger and LTs in the future I'd try to go the cheap way for now...

Cheap is good in my book. I knew the shipping was a little high (good example, haha) and also the cast mani's are only requiring $30 shipping. If I go for them, I'll talk to the seller about it, but I doubt he will care...

The Ebay manifilds look like a nice setup. If you can get those reasonably, that would be a steal.

Kinda what I was thinking. I wouldn't go crazy bidding for them either. If it happens, it happens.

So in the long run, maybe I should just stick with what I got, but shorties have such a pull with a decent price and some extra hp would be nice. I hate being indecisive...
 
C5's would clean up the engine bay a bit not having unused bosses and block off plates. That what I was getting at with the EGR and AIR systems.

If you're that concerned about the bosses send them down here and I'll cut and weld those bosses shut... got some 422SS wire on the shelf :D

I got rid of AIR and EGR on my Z28 to clean up the engine bay and remove all those useless hoses and that noisy pump....

The Predator is the single best purchase you can make if your engine is somewhat stock. It gets rid of this emission junk and the "performance tune" gives you a few HP.... it also eliminates this annoying 1-4 shift which by itself is worth $200 for a used Predator.
 
I didn't think you could weld cast? Or is it just cast iron that can't, or is at least tough to, weld. In all serious though, I guess I'll see if I can grab those headers and if not, I'll stick with what I got. What's your rate for welding, Karsten :D?

I didn't know the Predator could remove the emissions junk! Can it read codes as well? How about removing VATS? I tried to do some research in LS1tech about programmers (handhelds and full suites), but I couldn't find much on what the hand helds give you or allow you to do. May have to revisit this subject.

I also found a few nightmares on people buying used predators (and others) and couldn't tune their car because the VIN of the previous tune didn't match their car. I believe if the previous owner removed the 'predator tune' prior to selling it, it will be ok.

As for the skip shift, I was going to use a resistor and plug into the harness :1st: Apparently if you unplug the harness at the solenoid, insert a resistor into the plug (forget the size off-hand), then finally tape up the connections. The computers will read the solenoid as connected (and will still turn on the dash light), but since the solenoid is disconnected it will obviously not activate.

But if I can do it through a hand held, even better. God bless technology.
 
The stock C5 manifolds are cast, the camaro ones too. They have a steel (aluminuzed?) heat shield but they are heavy cast pieces for sure.
 
Nice. I wonder if they are any good. Any reason you picked that year range (98-99)? I found ones that are for the 00-02 which seem a better fit to my engine (2000) or at least possibly better. Seems like the 00-02 have one less flange on the header. I searched for shorty headers for the Fbodies yesterday and didn't come across these. I must have glanced over them. They seem to have some in SS and others in ceramic coat. I plan on wrapping my exhaust, but is one better than the other? I would assume SS would be best.

Oddly enough, their shipping is coming up as $44 for me so maybe that other guy isn't too far off, haha.

With our little metallurgical discussion, I thought you could cast stainless. I'm not positive on that, I don't really deal with casting much, mostly tubing. my stock manifolds seem very cast to me, but I have been wrong about other things before.

I'll have to look into the programmers. If they can do the things I want them to do, I will definitely be buying one.

Thanks for the help.
 
This is a LS3 manifold - this is definitely cast:

ls3.jpg

Below is a LS1 Camaro manifold - the heat shield is silver (aluminized?) and the tubes look like discolored 400 series stainless.

IMG_0803LargeSmall.jpg
 
That looks like a 409 set indeed, humm... I'm going to do a search hold on....
 
You're right....I never looked at them real close from a quick glance in an engine bay and seeing the rust and the heat shields, I figured they were cast like the vette LS1 manifolds but indeed they are 409.
 
Alright, I need some clarification.

When you guys say cast, do you mean cast iron or any metal part that has been cast?

Also, the predator sight doesn't seem to describe the features all that well. The forum doesn't seem to have the info either (need to know what I can delete). Off to LS1tech again...
 
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