n076720

The feedback from various forum members earlier this year was my 383 stroker should have a 3" exhaust all the way to the back. Seems no one actually sells these and magnaflow doesn't have mufflers at 3"'s either. So how do you folks out there that have Hooker super comp full length headers finish the exhaust system all the way to the rear and maintain 3 inches?

Gordonm

What kind of power are you making and what rpm do you spin it to. I ran my 500+ HP 383 to 7000 rpm with a 2.5 inch system. It was right on the edge of needing a 3 inch but the 2.5 made very good power.

n076720

500 hp and the torque should come in pretty close to that as well and the rev limiter will be set at 6500. What carb were you or are you running on that setup? If our power plants are similar how did you determined that you were on the edge of needing a 3" exhaust? The advice I received in May from various members was go with the 3" so I was trying to figure out how exactly one would do that since there doesn't seem to be pre-made stuff that fits.

Gordonm

At one point I was running an 825 Mighty Demon. I then switched to fuel injection. The motor is sold to another forum member still running the fuel injection.

I remember reading the flow of 2.5 to 3 inch pipes and the amount of air they flowed and the HP they could support. I know mufflers also have to figure into this also but my recollection is 2.5 will support a 383 to around 525 HP.

Can't go wrong with 3 inch just the fitting it is a little more difficult

n076720

But that is what I am looking for help with. I can't seem to find 3 inch exhaust components. Do people have this stuff custom made? What do people do about mufflers?

setty7

muffler shops can weld in either an interm pipe or "spacers" to make up for the loss of the diameters

n076720

So then any suggestion of a true end to end 3" exhaust is not really accurate. At some point, and it seems like the muffler, you have to reduce it down.

setty7

3" catbacks are hard to find for some reason. u actually might come out cheaper going with mandrel bent piping or if you go with a muffler shop im sure they have 3" piping as well. 3" mufflers themselves are definitely out there. just make sure you get the right offsets so everything will line up. hope i helped some.

cv67

My 383 is probably in the 550-580 range and recently went to all 3"

I think its too big, a mandrel 2.5 with a straight through muff probably would have been ideal (and quiete not to mention 3" systems are heavy!!!!). Maybe at the track this might make a tad more power...maybe. But 90% of the driving I doubt there would be a difference by going seat of the pants. Think most look at these online cfm formulas, max this max that and get sucked in, I admit I did even after going back and forth forever not wanting the "bottom of the page" pieces and I did lol.
Hope this helps.

drwet

Bigger is always better but I don't think its going to be worth the hassle you're going to have fabricating and fitting a 3" exhaust system. If you're willing to use a 2 1/2" system you can basically just buy it and bolt it on.

merc49

you will have to have the 3 in. exhaust made.ive never seen a system you could buy in premade pieces to install yourself.especially a vette.i have 2 1/2 in.and have the electric cutouts for racing,they are nice but too loud for the street.there is a new company i just saw in street rodder that is making 3 in. oval pipe which looks pretty neat but since its new its probably expensive.it flows like a true round 3 in. but being oval its still 2 1/2 in from top to bottom as installed.if you have a welder you could use elbows and such to fab it any way you want.

Danish Shark

If a small block 383 needs a 3'' exhaust what would a 502+ big block "need"?

gkull

Any quality muffler shop can do a 3 inch system. I also went with 3.5 inch in and out mufflers to keep back pressure down

Ironcross

this is correct!

including 4", except you will have to dig up the back yard to find the right tin can with all the money......those fancy exhausts are not cheap and really unnecessary unless there's some bragging rights that go along with them for the local cruises..........

63mako

Right. A 500 HP street 383 will do fine with 2 1/2" exhaust.

cv67

Heaviest exhaust trophy

I tell ya the full 2.5" system I pulled off my A body I bet weighed less than 50 lbs....the new 3" shipping weight was over 80. Ouch. Muffs almost half of that

2Quickrides

A 2 1/2" mandrel bent system with free flow mufflers will feed your 383 just fine. Until you're over 550 hp the price and hassle isn't worth the difference it'll make.

gkull

My friend has an oval 4 inch pipe setup on his injected 508 ci 1969 ProStreet Camero with 4 inch in and out race mufflers to get it down to the required Db level when he goes to the drag strip.

My idea is that if you are going to pay for a custom exhaust system the difference in price between 2.5 and 3.0 inch is neglegible. The 3 inch system will produce more power than a 2.5 Years ago when I was drag racing my 355 ci Vette i would uncap my headers by unbolting my 2.5 inch exhaust and install 14 inch collector extensions at the track. I had my jetting figured out depending on ADA. I don't remember the exact numbers, but my times were faster with header extensions. Later on I went to full length 3 inch and the times were close to uncapped so I just never unhooked it again

63mako

If you have a solid tappet cam and plan on 7000 + RPM shifts and or lots of dragstrip time where every hundreth matters go 3". For your typical hydraulic roller street 383 I don't think it is worth the extra effort and time. Might give up as much or more bottom end torque as you gain top end power.

n076720

Ah the beauty of this site where you get informed views and opinions from real world implementations. Seems we are pretty close to evenly split between 3 inch and 2.5 inch where the difference mainly comes from "if you are willing to spend the $$ then go with 3 inch but the performance of a mandrel bent 2.5 will probably be quite acceptable and a hell of alot easier to install". Thanks everyone for your replies and insight.