TheBadazz

Batazz LOL. Well it is, if your single mufflers flow is not enough. With duals coming out you can use two mufflers and each bank shares the flow. Two 900cfm mufflers can support more hp than one. That makes up the zero hp loss and great sound control. Best of both worlds.

mw66nova

hmm...i'm currently running a single 3.5" dynomax bullit. sorry badazz....got that spelling all messed up there...

skinny z

Uncork the headers on your car and those short little collectors will have your engine falling on it's face. Don't need to prove it, just try it. All that bottom end torque you had with the exhaust bolted up goes out the window because the tuning has gone for a sh*t. Just like the sub woofer you tune with a cabinet, headers without SOME sort of extention on the collector won't work very well unless of course you've built an engine that wants really short secondaries, like a top fuel engine that has NO collectors.
The point of the "magic box" is to provide the engine with what it believes is an open exhaust with the proper spec secondary. That secondary length is extremely important.
You like a sleeper? Show up with open header performance (and not just uncorked headers) with a relatively quiet exhaust and get plenty of suckers.
Incidentaly, if you run true duals and have a couple of glass packs, it's possible that you've hit upon a resonance that giving you exactly what you need it terms of exhaust.

Science is freakin' wonderful!

Rayzor32

cooool

skinny z

Removing your stock manifolds and single exhaust and installing headers with dual exhaust will give you more horsepower won't it?
No way!
If you think or know it does, then apply that same thinking to the next step in improving your exhaust. Open headers are a heat score.

TheBadazz

That's ok, what kind of power are you making. With a 3.5" bullit you should be ok, loud but ok.

1989GTATransAm

Just for giggles, when I run my car on DynoSim the difference between open collectors(termination box) and mufflers is over 30hp.

TheBadazz

That's about right with tunning. A non-thought out exhaust system will cost you a lot of hp/trq just like the wrong cam or intake. But some people don't mind that i guess.

mw66nova

well...that's a good question. my 305 has been 12.38 @ 108mph in the quarter at 3230lbs. raceweight...which by use of my magical online horsepower calculators equals ~ 327rwhp, but i think that might be high because my car is incredibly efficient. i'm not looking for optimal hp numbers necessarily, but rather the best combo for all out drag racing.

it is loud. right now it's unbareable as a street car because it dumps right in front of the rearend. i'm planning to take it all the way out the back and dump out by the bumper ala mufflex system. i want it quieter in the car, but i still want a loud sick nasty sound outside of the car. i'm no longer looking for a sleeper necessarily. new combo will be a manual transmission and i'm looking for ~450+rwhp...n/a.

ssean92

I hear ya on the loudness Matt, I havent ridin in the new exhaust setup but I couldn't imagine how load it is

__________________

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new best 12.1@114
Lt1 383 All forged Splayed caps,complete 4th gen Swap

TheBadazz

That sounds like a mean combo. 12.38 with a 305 that's real good. If it wasn't so loud you would make a lot of money around here. (Mudstain guys don't give the 305 any respect)

skinny z

And I find that worth pursuing.
Just not now......

skinny z

Hey Orr,
I checked out your start up vid.
How about some pics of the finished exhaust?

Orr89RocZ

well thats the thing, its not 100% finished yet. I dont like how low it sits and not sure i like how loud it is

I'll try to post up a pic of what i got so far and what changes i plan to make

skinny z

Cool.

Orr89RocZ

Updating:

Final pics of my setup for now It will change if i swap to a T56 or something over winter or fall, depending. Still low but gives me enough clearance to do what i have to do with this car, even tho clearance is about 2 inches...its scraping pulling into the garage haha but on the roads and with the new tires i have it should be closer to 2.5 inches total clearance









Kinda feel bad that after this LONG thread about good exhaust building ideas, i didnt fully go thru with the main idea of this thread. BUT this is the starting point for this motor. It can all change later if i dont like how it works. But I have tried the Split Flow by Dynatech and it was louder than i liked. I know sport the Dynomax ultraflo round 6inch case and i like it. it was loud too at first but did quiet down some with the tail pipes finally added.

I'm happy with what i have so far, its just a starting point for this motor. Its not the prettiest job nor the cleanest welds/install, but it is more than enough for me at this time

1989GTATransAm

Hi Orr

Good to see you are making progress and thanks for posting your update. Remember it took me about nine months to get mine all sorted out trying to figure out what the heck was going on with the motor. These thing can take some time.

Orr89RocZ

yep i think i have a trans problem and now a bad lifter noise it sounds like...so i hope one of the lifters didnt go bad already.

gonna change oil tomorrow and see what happens

Rayzor32

wow thats pretty low, you cant put a jack under there and try and bend that pipe up some more??

Orr89RocZ

already tried that and it didnt really move... it is very low but for some reason on teh street it kinda works good

skinny z

Good work.
I hope you still intend to pursue the tuned exhaust idea.
You have a chance to develop what you've got and expand from there.
Wish I could have stopped in on my way back from Virginia, but the scheduling was really tight.

Orr89RocZ

i think that would be beneficial... i'd love to do some open header tuning/testing with proper length collectors just to see how it goes over my current system.. Maybe i'll do that on the dyno someday but we'll see

Z THANG

I have long tube Hooker Super Comps on my 383 and ran dual 3" back to two chamber Flowmasters dumping at the rear axle. The shop flattened the pipe a tad that runs under and around my crossmember for clearance and we beat up the floor where the mufflers hang, gave them good clearance after that. The lowest thing on my car is the crossmember for my Southside Machine bars.

I had to put tail pipes running out to the rear of the car when I was hauling my kids around and it killed the motor.

1989GTATransAm

Hey Orr did you see the post on the Corvette forum where the guy made 475rwhp with a similiar combination to what you are doing? It was a very impressive performance. Nothing wild about the combination and the heads are very similiar to the ones you are using.

Orr89RocZ

his heads flowed like 286 and are comp ported 210's to my standard 195's. BUT the bench they used showed stock LT4 heads to flow 234cfm when most show near 250 so i bet those 210's flow closer to 300-305cfm easily

My cam is similar, slightly less lift but more exhaust duration and more cubes to my motor. i dont expect 475whp but atleast near 420 would be nice Thing that worries me is that he made that power on open headers i believe to my full exhaust theres that tuning thing

And my car doesnt idle that nasty like some cammed cars and so far it drives too tame to be a 400+whp car haha. even on base tune its driveable as can be and that worries me that its not making near the power i expect...we'll see tho

Rayzor32

im running a similiar setup on a 355, im thinking about going carb cos the fuel injection just doesnt have the power but im not going to give up on it yet gonna try some more until i want to throw it at the wall then ill go carb. With my combo im supposed to have like 400hp, doesn't feel like it.