exhaust mod opinions

[dohcfiend]

i am surprised i haven't thought of this be4. would having the crossover pipe remade out of mandrel bent piping add anything by itself or with a high flowing exhaust and a set or ported manifolds?

[Syn]

Re: exhaust mod opinions

i am surprised i haven't thought of this be4. would having the crossover pipe remade out of mandrel bent piping add anything by itself or with a high flowing exhaust and a set or ported manifolds?

try it out and let us know how it works

[Mach10]

I don't know what you're driving, but the 3.4 out of a 92 Olds cutlass auto had what definitely appeared to be a mandrel-bent crossover.

To be perfectly honest, I can't but help wondering if the best possible mod for pre 95 3.4s might in fact be to use two front manifolds and running a NEW crossover with a collector-style merge-point. The only problem with this style is that it is very hard to place the O2 sensor to where it'll "fire" properly (too far down line?).

This is how I run in my Fiero. Truth be told, I couldn't say if there was any gain 'cos the only time I drove this motor outside the Fiero was in a 2000lb heavier automatic cutlass.

[dohcfiend]

well, it will be a while b/c the motor in question is a 97. so running 2 fronts isn't an option for me.

i haven't had a chance to take off the shielding but i highly doubt gm would splurge for mendrel bent piping on a wbody.

every1 knows exhaust flow is a problem with these motors(or so i have been led to believe) as it is for most opposed Vee dohc motors. and i think one should take what they can get.

hmmm, my personal opinon would be there is something to be had from it but not by itself. heck, me and a buddy could probably make it from mandrel bent pieces. but i may have a pro do it if it isn't too high.

[Husky]

I have the sheilding off while I'm working on my turbo crossover... I'm 99percent sure it's mandrel bent. And it's got a flex joint in it.

[RedZMonte]

stock x-over is mandrel and does have a flex in the center of it. have had a couple of them apart. there is a little bit of power to be found in the exhaust manifolds. Look inside one of them, it gets very restrictive, and for a well breathing DOHC motor to blow threw them is definaly a restriction. well designed headers will be a great answer.


S

[Mach10]

well, it will be a while b/c the motor in question is a 97. so running 2 fronts isn't an option for me.

Sure it is. Grab 2 fronts, cut the flange off FLUSH with the runners, flip it over, have that surface ground flat and have it TIG welded back together.

[tijuana_no]

stock x-over is mandrel and does have a flex in the center of it. have had a couple of them apart. there is a little bit of power to be found in the exhaust manifolds. Look inside one of them, it gets very restrictive, and for a well breathing DOHC motor to blow threw them is definaly a restriction. well designed headers will be a great answer.


S

yeap! a well designed heaters will be the answer ,but no one has come up with heaters for owr engines and dyno to probe the gains.there is a few (i or 2 that i seen ),but there is always quetions about the product ,and the price to pay is huge.....i just hope someone come up with something good.

[Fierobsessed]

heaters? I think you mean headers...

But anyway. If you want to use two 96-97 front manifolds, other then what had already been suggested... what about an adaptor plate that bolts to the rear head, and has studs, or bolt holes in it. That way you could bolt up a front manifold to the rear. Other then ease of mounting on a Fiero, I don't think that it would yield much improvment over the stock rear manifold. That piece is actually pretty decent, even compared to the front manifold. Headers is the way to go IMO...

[dohcfiend]

i agree ultimately, b/c the cost probably would not be justified for such a mod. i am surprised there are no 91-95 headers yet as they are way more popular applications than the 96-97's

[HayesPerformance]

One note for all

One small tip to for all the buddies here. One thing that DOES give smaller reasonable gains through out the RPM range is WRAPING YOUR EXHUAST. One Product line our performance shop uses is DEI exhaust wrap. I would recommend HIGHLY that you use a Ultra High Temp Silicone Exhaust Sealant. It seals the wrap so moisture don't harm it or cause it to get soaked and rust of the exhaust, many toward the rear of the car. UNLESS you use Stainless Tubing OR if you make sure you TAKE CARE OF IT wash off any salt if you drive it in the winter, otherwise it won't cause you problems IF you use the coating I said to use.

WHY DOES WRAPING THE EXHAUST INCREASE EXHAUST EFFECIENCY???

Simple: Hot air LOSES Velocity as it cools

The wrap keeps the exhaust gases from cooling so rapidly, giving some gains to be had. It does work! Its just ONE THING in a list of things.

I have a list that I recieved from BANKS on all different areas WHERE ANY ENGINE LOSES HP. It is VERY interesting. I'll show it here some time.

Best to All,
David Hayes

[Husky]

Show away! With this motor, we could use every single "Free" pony we can get!

[tijuana_no]

hayes,would you recomend using the wraping method vs. using headers(thanx fieroblessed) that might not even be built right for this engines and expensive.

[HayesPerformance]

If you can afford it both.

[size=6]Well for ones that can afford both would be best, BUT I do realize that Headers are VERY expensive so far for our engines. So If you want to make the exhaust better for the least amount of money, then just clean the inside of the factory exhaust manifolds and good as you can, removing and metal flashing or casting lines. This WILL help a bit.
For the Exhaust wrap.
IF you only drive it in the summer then knock youself out and NEATLY and EVENLY wrap the exhaust.
OR
If you drive it year round, myself I would not use it on an exhaust thats got rust here and there, UNLESS you clean it PERFECTLY and first spray a few even coats of the HIGH TEMP SILICONE spray and then wrap it followed by another couple coats on the wrap.
AND KEEP THE SALT OFF OF IT.

Really though I would not put it on a stock exhaust. Sure it will help some, BUT It is a waste if you are going to be puting on a new exahust system.


A new exhaust design that I had be seriously looking into is doing an Exhaust on the front like my SHO, It had a performance exhaust on it that was VERY good at the front for a cross mounted engine.
The exhaust header faced down and went into a 2 1/2" round pipe that was mandrel bent and FLATENED TO a wide oval shaped that was very wide but only like a 3/4" high and ran UNDER THE WHOLE ENGINE BAY AND TURNED UP AND WENT FULL ROUND INTO A "Y" Connector where the REAR exhaust came down from the engine.
This would work on our cars BUT I would build a strong steel shield so that IF you hit your front frame area on a low driveway for exmaple it wouldn't press it totally flat.[/size]

Regards,
David Hayes
@ HAYES PERFORMANCE PLUS