Re: Headers & exhaust
 

Corsa w/headers, sans cats has absolutely no resonance but is LOUD. The sound is different (subjective observation). I had this system but grew weary of the LOUD (i.e. I could no longer drive around my small town without attracting a LOT of unwanted attention; resonance was never an issue.

My current solution is headers, no cats, and an LT-4 stock exhaust from the collectors back. No resonance and sounds stock in the cabin, but somewhat louder outside. Without a dyno comparison I can't comment on HP loss but in real-world driving it doesn't seem that I lost much, if any, and it "feels" like I picked up a little torque. Again, without a dyno that doesn't really mean anything but I'm reasonably happy with the system ... for now.

I haven't heard this setup yet but this might be my next direction should I want to change the exhaust again.

Re: Headers & exhaust
 

What's the FBI set-up consist of?

Re: Headers & exhaust
 

Marc favors the Corsa cat-back, but what Pete and others are using with success (in a fashion) is a "work in progress", but this may come pretty close as of now:

• SW or Watson headers,
• 3" pipes throughout,
• sans cats and resonator,
• SW or B&B type X pipe*,
• Dynamax 17228 or B&B muffs 3" in, twin 2" out
• NPP** valve on one of each twin outlet, OR cut-out valve at the differential
• B&B or C6 Z06 tips.

* Bob G is using what could be described as an X "box"
**NPP valves are controlled by simply supplying vacuum from the plenum to the valves, or manually electrically activated.

http://i185.photobucket.com/albums/x...s2001Large.jpg

Note: The simple vacuum system works well in relatively flat terrain. However, in mountainous areas, the simple plenum vacuum approach results in the valves being open "too much". The fix is what I was alluding to in the next HOTB.

P.

Re: Headers & exhaust
 

Pretty sure the 17228 mufflers are 2.5" dual outlets. Not 2"

FYI

Re: Headers & exhaust
 

What did you end up doing there Tomz?

Take any snappics? Did you pull the FlowMasters on there now?

I'm about to put on OBX's + PE pipes, and looking for more shots of the work...

Re: Headers & exhaust
 

George, this is exactly what I went through. Primarily Corsas over the years but just got tired of the Loud. I have headers, no cats and last year had Marc reinstall my stock '95 system from the headers back. The only difference is I had him add electric QTP cutouts and I installed a rocker switch hidden under the carpet on the right side of the console. The only issue is I had to sacrifice the spare tire carrier. On longer trips away from home I carry the spare in the back. I added small tips to direct the exhaust to the side. So far I like the setup a lot. It is stock quiet when I want and when open I can scare children and pets and set off car alarms. I normally run slightly open for a little rumble.--Bob

Re: Headers & exhaust
 

Hey schrade,ordered flowmaster catback actually yesterday took a while to find them cause they were discontinued but I found them,will figure out how to post pics when done installing them,headers will be next what's difference between obx & sw? Is it sound,looks I know thers big price difference . Thanks ill keep you posted.

Re: Headers & exhaust
 

I don't know much about the differences - when I said I know less than most on the boards, I was meaning exactly that...

Cliff [Dynomite] has one method step-by-step for uploading snappics here. You can practice a few carshots upload before the hardware gets here... Learning stuff like that has application in how some of the Z diagnostic stuff works too - promise.

Work shots are good in MANY ways - it forces you to take your time (always good), gives you more time to see where stuff is, good for re-assembly reference, feedback from others, if you ever sell, you got photo-doc'ed proof, you 'learn' the stuff better (I will NEVER forget steps involved in the Top End Resto thread ('til tomorrow anyway :mrgreen: )

Re: Headers & exhaust
 

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

Re: Headers & exhaust
 

Hi Ed, i got lucky typed 17115 flowmaster and bunch of company's popped up called every one,and all but one said nope don't have discontinued,finally one company said I have one on shelf,holy crap ill take it!!! So if you can't find something don't give up its out there somewhere.

Re: Headers & exhaust
 

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

Re: Headers & exhaust
 

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?

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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.

Re: Headers & exhaust
 

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

Re: Headers & exhaust
 

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.

Re: Headers & exhaust
 

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

(and INSIDE TOO http://www.zr1.net/forum/images/icons/icon14.gif ; 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)

Re: Headers & exhaust
 

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

Re: Headers & exhaust
 

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?

Re: Headers & exhaust
 

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.

Re: Headers & exhaust
 

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.

Re: Headers & exhaust
 

To each his own. seems to me that there is a reason why GM did not run 3 inch exhaust in the zr1. they probably thought they would have tons of complaints from the customers of the new zr1's complaining as to why the lt1's were smoking them off the line and why they had to rev up like a ricer to make power. My experience with too big of an exhaust proved it to me. In the end, I wound up selling that sweet 1971 mulsanne blue big block coupe because I just was not getting the torque I should have been getting from a healthy 468 big block. I didnt want to spend another 2500 for new smaller diameter side pipes so I sold it. I wish I kinda had it back again. That car was completely restored and won lots of trophies. After that car I stopped being a waxer owner and became just a regular owner.

ed ramos #3028

Re: Headers & exhaust
 

my black 90 has run 119.47 in the 1/4 with a 21/2 in drgas system and spin tech mufflers . the car only has plenum and injector housing porting headers, and a tune. wish I had the time to switch it to the 92 and see what the difference is.it has a 3 in system with a xpipe and super turbo mufflers callaway porting which is suppose to inc the heads and has only run 118.10 as the best mile an hr .both run about the same et.makes one wonder what is the best way to go ???????

Re: Headers & exhaust
 

So do we!!! That would be VALUABLE info.

Unless Ed has before and after dyno graph info here....................

Does Marc have dyno graphs on his site? I haven't see any info there...

Re: Headers & exhaust
 

no i dont have dyno graph info on my corvette or my old fox mustang. where i really noticed it was with my big block 71 corvette going to the super-competition hooker sidemounts killed low end torque in a torque monster like a 468 hydraulic cam big block coupe. I did have supertrapp mufflers on my fox mustang and I had something like 20 spacers just to drive around on the street but when I would go racing I would remove all spacers and the cap and run wide open exhaust. my exhaust was 2.5 at the header flange into a 4 inch pipe then into 5 inch super trap mufflers. but at 1200 hp it needed that. My big block corvette definitely felt like it had more torque before the header install. I am not surprised that bradley's 90 ran such a good mile an hour with 2.5 inch exhaust. If he had 3 inch he would probably have a slower 60 time unless he drops the hammer at 5k rpm which would only blow the tires away or chew up some u-joints.

I know that the ex-owner of my car said the few times he went to a track day that a buddy of his who had a 368 lt5 stroker, could not pull away from him on the straights at all and that surprised him. the only time his buddy would pull away a little is when they were coming out of a turn because his friend had 4.10 gears in his z and he had the stock 3.45. Sometimes these cars are like fine wine, some just have the right tweaks and runs like a bat out of hell while some have the wrong combination of tweaks and runs normally but not like one anticipates it to run. On another note, we know that each of these z's were dyno tested before leaving bowling green and I am sure, for whatever unexplained reason, some cars ran better than others which is why they wont release those dyno sheets.

Re: Headers & exhaust
 

I agree with Ed I think 2-1/2 is perfect for the z just wondering if I will lose any torque with headers? I know everyone saying you will get around 20 hp

Re: Headers & exhaust
 

That's why I went with those discontinued hard to find flowmasters force11,plus love the look & I'm sure they'll sound awsome!!!!!

Re: Headers & exhaust
 

you will not lose torque with the headers. your 2.5 inch exhaust system will have just the right back pressure to insure your torque stays around to do its work. its those big pipe systems that will not supply enough back pressure and the engine having to rev more to produce the backpressure it needs to have the torque. headers and flowmasters without cats and the resonator is perfect. It will last forever and the sound will be great when you are on it and nice when you are just cruising. no tinny sound out of the flowmaster system.

Re: Headers & exhaust
 

I will post pics when done,as for headers can't find anyone to install them here in Michigan once I get em.any one know of anyone in Michigan ?

Re: Headers & exhaust
 

I know what you guys are thinking ,install them your self ,hell no it looks like a pain in the azz,not going to start something that i can't finish.

Re: Headers & exhaust
 

got my exhaust,they look awsome!!!!!!!!:-D

Re: Headers & exhaust
 

I think you can do this with 1 hand. If you we're gonna' do the PS hoses, you can do the pipes...

Re: Headers & exhaust
 

they look great!! You will love these and they will tuck in nicely under your car. Congratulations on your purchase.

ed ramos #3028

Re: Headers & exhaust
 

If you don’t mind me asking... what diameter is the y-pipe where it goes into the resonator ?

Re: Headers & exhaust
 

Don't know, I'll measure & let know

Re: Headers & exhaust
 

thank you sir

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11inches

Re: Headers & exhaust
 

thank you very much :cheers:

Re: Headers & exhaust
 

This what is inside of your stock mufflers. Just in case you or anybody else was wondering. 2.75" shrinks down to 2.25" at the outlet. No wonder muffler swap gains good power improvement. I'm doing the same mod with my B&Bs.
http://i69.photobucket.com/albums/i6...ps25a6482c.jpg

Re: Headers & exhaust
 

How large is the inlet pipe where the two pipes meet and enter the resonator... 3.5"??? Can't be 11"

Re: Headers & exhaust
 

Just checked mine, 3.5" across, 11" if you wrap the tape around the pipe.