First off, I don't have a 3rd gen car but I have a 3rd gen engine. Its a 383 HSR with AFR heads in a 1990 C1500 truck.. I currently have 1 5/8" full length headers made by Hedman and I am wanting to run 1 3/4" headers. However, the hooker supercomps are the only one's in a 1 3/4" primary but I have tried to fit these on my truck with no success. I was thinking about custom making some but I have no experience making headers....I did build my exhaust though.

What is better....a 1 3/4" shorty/mid length with a nice long smooth transition collector with equal size tubes or a full length 1 3/4' with a short collector and 3-5" close tubes?

Or if you know of something that might work to exit toward the rear of the engine instead...let me know b/c my 1 5/8" headers are killing me above 5400 rpms.

 

You may want to get a hold of Dyno Don on here. He makes custom headers for our thirdgens and he may have some ideas for you.

 

Thanks. I sent him a PM before I posted and he said he doesn't do anything but f-bodies but hopefully he can give me some info.

 

Between shorty, mid-length, and long tubes?
In theory a long tube should make more power....however, what about all of the factors in the thread so far?
Primary size?
Collector size?
Primary lengths?

Primary size effects the powerband. Collector size and shape effects scavenging and the ability to pull exhaust out of the exhaust....merge collectors are to be shown best at this. Primary lengths.....the equal the pipes are to each other, the most power would be made. However, what would make more power between a set of long tube headers(1 3/4") with non-equal length primaries with a 3" standard collector vs. long tube headers with non-equal length primaries(1 3/4") with a 3" merge collectors vs. mid-length headers with equal(with 1-2" of each other) with a 3" merge collectors?

If those were your options for a power range of idle to 6500 rpms? Or is there a better way of thinking....obviously long tubes with equal primaries would be better but not everyone has the room to make custom equal length long tubes.

 

Here is what Larry Meaux of PipeMax fame and also an excellent head porter has to say about exhaust systems. Here is his list of the most important items regarding the exhaust and in order.

1. Collector length
2. Collector diameter
3. Primary pipe diameter
4. Primary pipe length(least important)

I have exhanged posts with Larry on the subject of long tube headers versus short tube headers. He has been involved with hundreds of dyno pulls and has aquired a ton of data.

Anyways his experience is that a well constructed set of short tube headers can approach the power of long tube headers. So if you can get the first 3 items on the list correct you will probably be 90% of the efficiency of long tubes. I think it can be said that a well constructed set of short tube headers will be better than a poorly constucted set of long tube headers.

Anyways my two cents on the subject.

By the way on my motor I'm using Dyno Don's 1 3/4" shorty headers with air for passing smog and making 1.3 horsepower per cubic inch. I plan on upping that to 1.4 horsepower per cubic inch on my next build and again with Dyno Don's 1 3/4" shorty headers. I bet I would not gain over 10 horsepower going to long tubes.

 

Thanks. Well, my 1 5/8" headers covers up the corners of my AFR exhaust ports. So, I was going to switch to a 1 3/4" to unveil the rest of the exhaust port and that by itself would free up power. Then while I was at it...it would require a custom set anyhow to accomplish this, so I was going to work with a mid-length design with a merge collector style.

Is there a special formula to figure out the collector length?

 

I use Larry Meaux's PipeMax program for my exhaust specifications. Sounds like you are on the right track for the custom headers.

 

I was going to pick up the collector and header piece that attaches to the head that is all ready done so that I would just have to follow/think about the design of the pipes/follow my long tube pipes from my 1 5/8" headers.