I have a 92 Z 350 tpi, has anyone noticed if their is a real difference in performance compairing shorty headers to full length headers. which would be best for my motor. I have duel cats with straight pipes and duel turbo tips. also not having a muffler and just the cat's(which are stock) is this hurting my performance. would I be better off with the flowmaster and get rid of the tips. It sounds great even with stock manifolds. and could I use the tips and flowmaster together or would this be too much back pressure. need headers but dont have to be smog legal.

 

One of the problems coming up with such a comparison is other changes that would naturally occur when changing from short to long tubes, for instance. But, perhaps someone actually has a comparison.

FWIW, I don't recall reading anything to that effect. Theoretically, the long tubes work better for scavaging because the pulses are better tuned to the engine speed. In reality, though, there probably isn't enough difference to warrant the extra things you have to do to make long tubes work, especially on a mildly-modified TPI.

For reference, a buddy here runs a highly modified ZZ4 TPI engine with the dual cat system, through port-matched LO3 cast manifolds. His sea-level corrected times are in the 13.4-range. He's got shorties in his near-term plans, which will probably get him a little closer to 13 flat. I doubt the improvement from shorties to long tubes would be greater than the improvement from cast to shorties.

As for you muffler/no muffler question, it's probably moot by the time the exhaust gets back there. Flowmaster w/tips I'm sure would be just fine.

 

I've read numerous places that shorts are good for upper RPM and longs are good for low RPM torque. I'm sure it's due to the scavenging effect of the longer tubes, like you said five7kid.

Unless you are a diehard modification guy, short tubes are WAY more practical for our cars. Mainly due to ground clearance, as well as the starter, oil filter, etc.

I know a few people on here have done it, and that's cool as hell. There's nothing like squeezing that few extra ft/lbs. of torque out of an engine. But you make a few sacrifices in our cars.

AJ

 

I was trying to stay away form the full length headers because of how low my car is and the room to work on the starter and so on. does any one make a shorty kit with y-pipe for the duel cats. and do the flowmaster mufflers realy make a difference. I real like my turbo tips they sound and look

 

If you lowered your car, then forget about Long Tubes. But to end the discussion on whether long tubes give you more HP over shorties, then yes there is a noticeable difference between the two. If you go over to the cz28.com LT1 forum, you'll see that almost every car with headers there has installed Hooker LTs or FLP Long tube headers. Why? Because they give about 10 rwhp difference over shorties on the dynoon about stock cars. Plus these headers sound bad ***, lol! The gap between the headers widen when you have more stout mods to the car...there's this one guy on there with ported stock heads and Hot cam that gained 23rwhp switching from SLP shorties to Hooker Super Comp full length headers. I run Hooker LTs on my IROC because it allowed me to get my own bad *** custom exhaust.

 

Remember that usually when you read about comparisons between short and long tube headers, they're usually talking about equal length headers too, not the bastardized things we use on our cars.

 

Bringing 4th gens into the discussion is moot. They've got better stuff available to them, like the aforementioned equal-length LT, and the LT1-LS6 engines are, well... real engines, don't 'cha know.

 

There's no comparison, Bluegrassz! I've got Hooker Super Comp LT's dumping into a 2.5" X-Pipe with Hooker Tuned Megs just before the axle on my '89 GTA. The shorties are better than stock, but unless you have cam and head mods to take advantage of the rpm power of the short tubes, you would be wasting your time. LT's are for torque! That's what 3rd Gens are made for. And for those who think duals are too hard, I can tell you from experience, they're a breeze.

 

Do you all think there is a significant differeance between the equal length and the unequal lenght? How much more ground clearance do the LTs give up over the SLP's. Any exact measurements by chance? Thanks

 

Equal length primary tubes is almost as big a myth as "backpressure". If our engine's had the "perfect" firing order (which doesn't exist) then it MIGHT make a difference.

Think of it this way. The firing order of a SBC is 1-8-4-3-6-5-7-2, with the exception of the LS1. How is that gonna take advantage of equal length primaries? The pulse widths are way to eratic for any real advantage of equal length.

A bigger benefit would be to make all the primaries of different lengths so that the pulses of each cylinder would reach the collector just before another one. But then you still have the problem of the firing order. Some of the tubes would have to be way too long to fit into any car.

AJ

 

With equal length tubes even though we can't do anything about what happens past the collectors, at least each cylinder experiences the same scavenging at the same RPM from the pulse moving through the primary.

And if you're really worried about it, you can go ahead and try to find some way to fit a 180^o header under your car.

 

Double post

 

I also thought about going with the full length hedman headers, with the duels two flowmasters and turning them down just past the rear end. By the way I also seen a true duel 3" exhaust on a 86 ta with a 406 and a 5 speed. The pipes were tight over the rear and had plates tack welded ever so often to run the pipes parallel with a little space between them . The plates keep the pipes from rattling. The car also had full length headers. I just wasnt sure if I was just throwing money away for the shorties.

 

How do the headman headers compare to the Hooker headers (performance, clearance, etc.)? I know the headman's are alot cheaper but would last just as long with the coating. Thanks

 

Bluegrassz

Hedman's can be used just as well as Hooker's, but Hooker's go through a better manufacturing process. Better fit, better quality. But if you're on a tight budget go with the hedmans. They're still lt's. With the proper install, the header collector will be the lowest part of the exhaust system unless you use rectangular mufflers(such as flow's). They cause clearance problems which can be overcome. But try the megs or bullets(easy fit). However, don't give yourself the headache of trying to go over the axle, dump before the axle. BTW, 3" is just as easy as 2.5". I went 2.5 because there is no need for 3. I want to keep velocity.

 

will the exhaust fumes get into the car if I dont run it all the way out or turn them out in front of the tires. Im gona try to get rid of the duel cats and replace them with muffler I thought that would be a good place for them. what cha think!

 

Bluegrassz, exhaust fumes will not be a problem. I have an '81 Camaro and an 89 GTA that runs the same exhaust setup. No problems. However, clearance could be a problem if you try to go out by the rear tires. I just turn down and dump at the center of the rear axle.

 

what kind of mufflers did you use, and did you put them where the cats where? and what size pipes did you run?

 

Yeah, and they're in real ugly cars too... actually I like the vettes, so I can't go there though.