I'm getting together some ideas for an exhaust system on my '78 Malibu bracket racer. I'll be welding up a system this spring. This is a 95% strip/5% street car (gotta make a few cruise-in's with it) car. I've heard some good things about Doctor Gas pipes, anyone have a link?

All help appreciated!

Here's the motor:

-1974 454 cid 2 bolt block .060 over
-GM forged steel crank
-GM forged steel rods, 3/8 ARP rod bolts
-SRP forged billet pistons, 12.7:1
-SRP chrome moly rings
-Lunati solid 292/301, 259/267 (@ .050), .625/.625, 110 LSA, 3500-7200 rpm’s
-Cloyes true roller timing chain
-Edelbrock Victor Jr. rectangular intake
-Moroso seven quart oilpan
Moroso high volume oil pump
-SFI approved dampner
-SFI approved flex plate
-GMPP Signature Series rectangular heads
-2.19/1.88 Manley Severe Duty race valves, 11/32 stem
-Crane Gold roller tipped rockers
Crane one piece pushrods
-Crane guide plates

Make some holes on the fenders, weld up some pipes to the headers and let them stick out the sides of the car tongue.gif :D

You looking to have dumps? Come out in front of the tires? All the way back?

http://drgas.com/

Sounds like a kick ass motor! graemlins/thumbsup.gif

Well...I was thinking collector, x-pipe, muffler, dump, which would put it somewhere in the area of just in front of the rear wheels. I was hoping some bracket racers would chime in and give me a good combination that works. The only thing I've ever raced was my Chevelle with a full exhaust, so I'm not savy on all this high speed racing stuff.

Sean,

3" mandrel with straight through mufflers like a Dynomax or Straightline, etc.

I didn't find that a crossover did anything in the way of an ET slip. It did smooth and change the exhaust tone and quiet the car down some though.

personally, i don't like loud, so i'd want it to be as quiet as possible, but it makes it hard to concentrate on what you're doing when you're up against some loud-ass bracket car with open headers. so i would second the notion by "dragracer".
if you want "savy, high speed" advice, you might have better luck getting it from a heads up racer, not a bracket racer. most bracket cars around here are over-tired, and under-powered. not all of them are like that, but most of them are.

Originally posted by m71:

if you want "savy, high speed" advice, you might have better luck getting it from a heads up racer, not a bracket racer. most bracket cars around here are over-tired, and under-powered. not all of them are like that, but most of them are. Ouch! :D

For a race car, Pipemax recommends:

2.03 x 37.4" primaries, including the port length
3.79 x 20.5" collectors

Best wave performance from 5000 to 6800 rpm.

Anyone else wanna chime in?

For headers I think a set of 1 7/8" or 2" primary tubes with Flowmasters "Pulse-Tech" 4-2-1 collectors. (3.5")

For an exhaust system a good 3" mandrel bent X-pipe (Dr. Gas) and a set of Dynomax UltraFlo's with either turn downs or tail pipes. graemlins/thumbsup.gif

Sean,
The 78 Malibu I just picked up has a 12:1 406 SBC and runs the same ET/MPH with open headers or the exhaust. 1 7/8 Super Comps, 3 1/2 pipe w/ crossover to Cherry Bomb mufflers set as far back as possible and dumps at the axle but angled/turned to aim outward past the rear of the tire. These aren't the Cherry Bomb glass packs I'm familiar with from the 70's, they look like any other straight thru muffler.

I don't like the open headers, too much noise and I want to hear whatever else the car is doing.

With your compression and RPM you will be turning I believe 2" or slightly larger headers will be best. All of the bracket cars at my track running high comp. BBC use 2 1/8 or larger and usually no mufflers, just dumps.

Good luck with your project.
Gary

oops double post!

Maybe I should have clarified. I have Hooker SuperComp #2241's already, 2"x3.5" Very few headers will fit a bbc swap into a Malibu. Hedman makes a p/n, and I believe there's one other, like Schone.

Sean, your Hooker's are close enough to onovakind's recommendation to "fit".

Dr. Gas is EXPENSIVE. I beleive you'll be able to find a 3.5" X 3" X-pipe from another manufactuer, cheaper IF you choose to go X pipe. Another , seemingly parallel solution, is to weld the scavenging collectors onto the Hookers and then JetHot the whole assembly.

As saidbefore, I would use a straight-through type design. I know many bracket guys have been recommending the Dynomax race mufflers. Run some searches on them.

Use dumps before the axle for sure, else you'll have to weld a second set of flanges into your X pipe system for tranny R&R, etc.

Wouldn't bother with an H crossover, as it doens't seem to gain ET, while an X might give a barely measureable gain. ( It won't with scavenging collectors in place). I find the X helps with low end torque/driveability on a big tube, big port, small rat, but that won't be an issue for your bracket car at all.

You might consider the scavenging collectors and a simple headpipe/muffler behind them. See what the racers tell you.

I vote for using the Dynomax welded Ultraflow mufflers in the 3" in/out size. Nice tone, not too loud and flow extremely well. I'll shoot you some pics of my system this afternoon.

Originally posted by 427L88:
weld the scavenging collectors onto the Hookers and then JetHot the whole assembly.
This is what I did with my 2" Comp Hookers. Had a welder at work fab this up for me. Worked out pretty nice. graemlins/hurray.gif

Check this place out http://www.pypesexhaust.com/sys-chevelle.html I have heard good things about their fit and quality. I believe they also let you substitute mufflers.
Just throwin another one out there for ya!

Thanks for the suggestions, guys. I've got some planning to do now. :D