Headers & exhaust

[edram454]

man u lucky dog. I think its the best system out there. I have had flowmasters in various cars and its always been a good product. I love the sound and the lack of drone. dont use the cats if you dont need too. Just the resonator and mufflers and you will love the sound. I dont need a new exhaust system or anything just the thought that you cant get any more makes me want to buy another spare. The pipes are galvanized steel so they will last a very, very long time. Good luck and enjoy your new flowmaster exhaust.

ed ramos #3028

[Schrade]

Originally Posted by edram454

Tom,

where did you find them?? I have flowmaster force II system and they are discontinued so I thought. Are they making them on a custom order method or did you just get lucky and find an old set somewhere?

ed ramos #3028

Who DID have 'em there Tomz? We might be able to get more parts from 'em...

Did you get some snappics of the car uploaded there?

[TomZR1]

Got them from tko performance .com guys name is Ed ,as for pics I'm working on it wright now hopefully I can post them.

[TomZR1]

Here's the exhaust I have on it right now looks hacked up

[TomZR1]

I will post more pictures when exhaust is done and car is detailed. The car is a mess right now and the garage in under construction.

[Schrade]

Originally Posted by TomZR1

I will post more pictures when exhaust is done and car is detailed. The car is a mess right now and the garage in under construction.

What's wrong with the car? Looks pretty good to me...

(and INSIDE TOO ; if it was my setup, the sleeping bag and toothbrush would be near the car - I can't hack under 40' - to easy to drop bolts with cold digits)

[edram454]

About exhaust systems in general. When I was racing the quarter mile, we did many test on exhaust systems. We discovered that the biggest exhaust system is not always the best system as far as making power. 3 inch dual exhaust system is for cars making tons of power.. lets say 600 hp or more. big inch pipes will move more exhaust out but if you dont have the power, it will kill your torque numbers too. LT5's are not known for there torque so cars that are not stroked to a bigger size or heavily modified will suffer in the low end big time. I had a 468 cube Corvette that I decided to put full competition side mount headers on it and even after a fresh rebuild I lost torque compared to my stock exhaust manifolds. I should have bought the regular competition header which were smaller and created some back pressure to maintain good torque numbers. I finally decided, since those exhaust cost me so much money, to change the rear gear to a 3.55 from a 3.08 diff to try to make up for the torque that I was losing.

On the other hand, on my 1200 hp mustang I had 4 inch exhaust dumping to 5 inch supertrapp mufflers. That car had to have that kind of exhaust but I dont think our zr1's will benefit much with 3 inch exhaust and will lose a certain amount of torque. I would imagine that on big inch 415 cube lt5's it would work good but on the rest I would bet it would not work as good as 2.5 inch exhaust. Of course if you put cats on anything you are destroying top end and torque numbers. If all you require is a visual the hollow out the cats. One 3 inch pipe flows more than 2 2 inch pipes for example. 2 2.5 inch pipes is just what the doctor ordered on most of our torqueless cars. Our cars are rpm horsepower makers and everybody knows that torque always wins on the street. I would not sacrifice any of my torque just to put a bigger pipe and maybe some more peak horsepower. By the time you get to your peak power at 7200 rpm... the race is over.

fyi.

ed ramos #3028

[Schrade]

I think I've read that bigger pipes allow the gasses to cool quicker. And cooler gasses are heavier.

If so, more 'power' is needed to push the heavier mass to the rear.

Is there some additional theory here?

Turbulence? Laminar flow?

Header wrap to retain the gasses' heat?

At what point is the resonator restriction inlet of '90 overcome with bigger pipes? What size???

ed.:
How much torque did you lose on those machines there Ed? Did you ever get dyno graphs before and after?

[mike100]

Originally Posted by edram454

...3" pipe discussion...

The LT5 defies convention... 3" pipes seem to work very well along with the oblong 2" primary header diameter. I would like to try out a 1-7/8 set of longtubes, but seeing as how that's about the same size as stock, it is obvious that this engine is a little unique on tried and true hot-rodder dogma doesn't strictly apply.

Given that, I'd probably prefer to run the metric sized stock pipe which is right at about 2.7" diameter (which in itself is a clue that GM knew 2.5" was too small). My 5.0 mustang and LS3 cars both have pipes smaller than that and make similar power at similar revs, but the LT5 just seems to like the big pipes and i can't totally explain it. If anything, it moderates the torque at and below 3500 rpm making it a little less likely to spin off the rear tires on the roll. Also, the ZR-1 has never been the king of 60 ft times - it's all about the top end and not having to shift as much.

[XfireZ51]

I agree w you there Mike. As an FYI, my stock block uses 1 7/8" primary tube Watson headers. Not sure the collector is even 3" but it all dumps into 3" pipes, no cats, from there to the 2 outlet DynoMax muffs. My torque peak, 402SAErwtq/411 actual, peaks at 5200rpm. Of course we are talking about a stock block 5.7L but ported heads, TB, and top end using both intake and exhaust cams. I think the "lack" of low end torque has more to do w the characteristics of 4V motors and less to do w the exhaust system diameter. For me, I'd rather trade that low end grunt for what happens once the car gets beyond the 1/8th mile.