All,

I'm trying to figure out how to configure my exhaust. Seems like there will be a trade off no matter how I go. I currently have factory cast SBC manifolds and factory sidepipes. I like the look of the factory sidepipe covers and would prefer to go with an option that keeps the covers. My engine is a built 383 with the following:

CAM: Dur @ .050 230/236, lift .510/.520
Intake: Edlebrock RPM air gap
Heads: Dart alum pro 200cc runners
Compression: 10.25:1

Here are the options I am considering:

1. Block-hugger shorty headers with a crossover and classic chambered pipes. This gives me the crossover, but shorty headers will reduce any high rpm scavenging.
2. Hedman sidepipe headers. These give me longer tubes, but are not tuned. Probably would give me some high rpm scavenging. I don't think the configuration would allow a crossover though.
3. Blow off the stock look completely and go with something like the Hooker system.

Would appreciate any comments on the options from the group - or any other suggestions.

TIA
Greg

 

if indeed you are going to campaign the car with open headers is one thing. however, once you hook up headers to mufflers, it negates most of the gain the headers give you.
ported stock manifolds may be the way to go. you will probably gain hp with headers over the stockers, but how much could be minimal if you are doing mostly street driving...jmo....good luck....

 

I guess I forgot to mention that I would go with something like classic chambered to open up the exhaust with the headers. So, you think that the headers don't really buy anything even if lose the stock pipes and go with something less restrictive, but not completely open?

 

I have under car exhaust but i installed Hedman 68306 headers on my car and i am very pleased with them

You will have a gain in power and since they are ceramic coated it was quite a difference in heat inside the car when i swapped from regular headers to Hedman ceramic coated headers
When the weather gets nice and warm i will take off the exhaust and have the 2,5" stainless steel exhaust pipes ceramic coated as well

I am sure you get these headers for sidepipes as well

 

im' sure the headers will "buy" you something but how much, i don't know
maybe there is some research on a dyno with what you are asking?...hopefully not by a header manufacturer but independent study?
could be there are some c/f members that had that done, try a post.
whether or not the issues with headers make it worth while as far as leaks and heat etc. could offset the gain depending on how much you run un capped....jmo.....

 

Headers are a complete waste of money on the street and most of them hang too low. Just how much are you going to be spinning your engine above 6k to gain any top end advantage? Port match your stock manifolds or go to something like McJacks......i know i'm going to get some flack from the tuned long tube header crowd but that's for the track imo.

 

My understanding is that chambered exhausts are very restrictive.

1.62" long tube headers with H pipe close to collectors (or better yet an X pipe if it will fit) and full 2.5" exhaust with low restriction mufflers. Note that loud does not = low restriction, do your homework.

You can probably even go with 1.75" primary tubes in your CI range, though that will hurt the low end somewhat.

Two empty resonator cans about 12" behind the collectors will make the headers think they are open. 6" by 12" long is ideal, shorter and narrower will work, but not as well. The inlet and outlet pipe to the cans should extend into the can about 1".

Doug

 

I have those too and love them. Especially nice is the ball at the end. No leaks like the good ole days. Once I put on the crossover, it became my favorite sound.

 

Talk to Dennis Beck. He has a ZZ383 engine in his vette using shorty headers and he says his car runs like a BEAST.

http://forums.corvetteforum.com/memb...nnis-beck.html

 

Greg,

I have a 383, Dart Heads, Lunati roller cam, 11:1 compression (a little on high side) with RPM Air gap intake, with hedman coated side pipe headers and with 2.5" Classic Chambered side pipes, 5-speed & 3:73. All my suspension and driveline are fresh and my car runs like a beast. Oh, I am at 7K of altitude in CSprings too. Can't imagine what it will be like to get down to sea level...will probably have to put on something other thn stock sized tires to keep me on the road.

I have had two 383s and the one I mentioned above isnt as nasty as the last one I had BUT, a good flowing 2.5 inch or 3" (if you want to fight getting it to fit) exhaust. Personally, porting exhaust manifolds seems like too much work..coated headers are relatively cheap...I think I paid 350 bucks for my set of SB Hedman side pipe coated headers. Personally, I prefer coated headers because they really cut down on the heat/more civilized...cleaner look; you'll be real happy with them.

I have had both undercar and side pipe setups always using coated headers...I like the look of the side pipes on my 67 better than under car...others may think different and thats fine.

The side pipes do rattle my brain, but I don't drive the car that much and when I do I like IT!!

Cheers,

Frank

 

Thanks Frank. Based on pictures of seen of this install, it does not look like there is room for a crossover pipe after the collector. What do you think?

 

Do you have any pics of your setup?

 

Ahh..apologies, I missed the crossover piece of your question...

I have seen a form member who added a crossover on a set of factory side pipes. I thought about adding a crossover to my current setup but never applied any brain bites to "how". Like anything else, I suppose a crossover could be fabbed up when using a set of coated side pipe headers but probably not worth the effort/practical.

I have always heard good things about exhaust crossovers but no personal experience.

So, I would say that if a crossover is a priority then I'd say the side pipe with header option is probably "out".

Undercar is probably the best way to get headers and the crossover. I have seen pics recently on this forum of a restomod (I think) with under car exhaust and a custom shaped (read "flattened) section where a crossover was integrated. The system was tucked under the rear and looked killer, for sure. I have also seen a crossover done on a more traditional under car exhaust set up and it looked fine. I have no idea what the performance "claims" are in either of these configurations.

Cheers,

Frank

 

Here is an example of what I have seen with the shorty headers. It includes a crossover. My fundamental question is whether this setup would be better or the longer tube headers without a crossover. As Frank said, I can't imagine how you would get a crossover in with the longer sidepipe Hedmans. Anyone else with a different setup feel free to jump in.

 

The only pics that I currently have would be from the top of the engine so it looks pretty normal as far as headers go. My system is out the back and the cross over pipe is right near the end of the transmission. I also have the 2.5" chambered exhaust and a little less cam than you. I have posted the sound on other posts, but here it is:

 

Hedman long tubes with 2 and a half pipes to the back, and Walker turbo 14in. mufflers with short tail pipes (maybe a foot). Big gain in street performance over Hooker sidepipes. And sounded really great.

 

It sounds like you have the XR282HR cam as those specs match mine exactly..

In another thread I have going I have the Headman side exhaust headers and Sweet Thunder pipes.

Pretty bad **** sounding..

http://forums.corvetteforum.com/c1-a...r-install.html

 

It looks like you modified the collectors and removed the flanges. Is there room for a 2" crossover connecting where the bung is?

 

I'm sure that you could, but you end up reducing your ground clearance from when I looked at it while it was on the lift.

David

 

I have been thinking of adding a x pipe to the under car exhaust

Any here that have the x pipe?