exhaust size

[duo-stripe]

Hey guys,
I've got a question about exhaust tube-sizing: in my 69Runner I am running a stroked 440 ( now 496 ) with Ross pistons, Isky cam ( pretty stout but dunno the specs ) standard, non-ported 906 heads. Stock exhaust manifolds and an Edelbrock TM-7 singleplane intake.
Would 2,5 inch diameter all the way would be big enough or should it be at least 3 inch in diameter? I am also thinking about removing the flowmasters ( 40-series with deltaflow ) and replacing them with glasspacks...
Does anyone have any answers on this matter?
thanks,
Marcel
the Netherlands

[is_it_EVER_done?]

For street performance use, a "cheap" header with 1-7/8 inch tubes will deliver better performance. For race, you may gain a fraction with 2 inch tube, 3 to 3-1/2 inch collector headers, but even on a stroker motor, you will give up a bit of torque with race type headers.

As for mufflers, a glasspack will cost you a significant amount of power over any other type of muffler. They are 'low and loud' as far as sound goes, but a chambered or reverse flow muffler will give you a noticeable improvement in performance while not being obnoxiously loud.

[duo-stripe]

hmm, so 1 7/8 headers it is. Would Flowmaster 40-series WITHOUT Deltaflow do best? And wouldn't the standard heads won't be a problem?

[is_it_EVER_done?]

First, I meant to type 1-3/4 to 1-7/8 inch headers, not JUST 1-7/8 inch. I doubt you would notice any difference with either size.

As for the Flowmasters, they have never been considered a true performance muffler, as many others will produce more power with less sound volume. Personally, I love them, but brands such as Dynomax, and others will give a couple extra HP, and be a little quieter.

What are you trying to achieve as far as sound and performance? I assume you have Delta 40's already and are not happy with them. If that's the case, what are you wanting to change/improve?

[duo-stripe]

I now have the 40s with Delta. The exhaust that is now under the car wasn't fixed properly and looks like *&& so this has to go. As far as performance, I drive the car on sunny days so it doesn't have to become a dragracer, but I really want a performance sound and especially a brutal sound at idle. I never run the engine beyond the 5500 rpm range ( i even don't know if it can make this kinda rpm..)

[is_it_EVER_done?]

Since maximum performance isn't what you are after, I (my opinion) would go with 1-3/4 inch headers, and the glasspacks that you initially asked about. That will give you a deep/loud sound, and if you don't plan on revving your engine to high RPM's, you will probably never notice any difference in performance, and may even gain a bit off the line/low RPM.

If you don't like your Delta's, you probably won't be happy with the non Delta's, since there is not allot of difference.

[duo-stripe]

I've phoned a friend of mine today, he has a few old glasspacks and old headers so we're gonna try that stuff this weekend, if it works I m gonna buy some new stuff.
Thanks for the info, and i will keep you informed,

[firefighter3931]

A 17/8in header is the smallest you want to run on a 500ci motor. A 3in exhaust system with an x-pipe and a true "flow thru" muffler works way better than the chambered flowmaster junk. For mufflers look at magnaflow or dynomax ultraflows. 

Ron

[duo-stripe]

Hey Ron, I still run the standard 906 heads...won't that give me any trouble? They have the original porting size.

[firefighter3931]

Naw, the 17/8in headers are fine with a stock iron head. If you're thinking about aluminum heads in the future you might want to purchase a header that is compatible. The hooker 17/8 COMPS (not Supercomps) will work with an angled plug head but you'll have to place a few dings on #2 & #8 tubes. Of course the TTI's will fit flawlessly.

The thing to remember about headers is that the tube diameter will influence the engine's behavior. The smaller the diameter, the lower the torque will come in. On a 440, the 13/4in header brings peak tq in at approx 3000 rpm so on a stroker it would be even lower...probably closer to 2500 or so. You don't want the header dictating where the engine's powerband will come in.....

Even with stock heads that 496 will be close to 500hp if not slightly more. The big dog needs to breathe 

Ron

[duo-stripe]

hmm, so headers it will be; I looked on the websites of dynomax and magnaflow last night so I am now figuring out which kinda mufflers I will take. Now I have to see in some headerwork. But 500 horse..darn..that is enough. I used to have a 318 68 Charger automatic, this 4speed runner is something else.
I must look into the specs of the cam, Ron, and will let you know. It is maybe interesting for you to have some more info on this..
thanks

[firefighter3931]

The Dynomax Ultraflow is a fantastic muffler....moves lots of air and isn't restrictive like a flowmaster. Nice rumble at idle and sounds hardcore when you jump on it. 

When ya dig up the cam specs... post them. The intake manifold is descent as well....i like the TM7; it performed just as well on my 446 as the Holley Street Dominator. You just need to work on getting the exhaust out of the engine at this point. 

Ron

[duo-stripe]

Ron,
Got this from my buddy who gave me the cam:

TW 81G

ISKENDERIAN

2P  08

280HL   HYD

1651

Grtz Marcel

[duo-stripe]

found something I think:
High Performance use, lopey idle. 2500 stall, 3.70-4.11 gears, Up to 750 cfm, 9.5 CR.
RPM range 2500 tot 6500. .465 lift int/exh, 280 gr. duration, 108 lobe center.

[firefighter3931]

Looks like you found the cam info.  That is actually a pretty small cam for 500ci, but it will make killer torque.  The advertised power range applies to a 440 engine. The stroker motor will absorb a lot of that duration and tame it (the cam) down. You need headers with a cam like this, the lsa is 108* which is tight for a restricted exhaust system (manifolds).

What kind of fuel are you using with this combo ? What's the compression ratio ?

Ron