Opel GT Forum banner

1 - 10 of 10 Posts

·
Life Long Opeler
Joined
·
692 Posts
Discussion Starter #1
Hey, what are the advantages of using headers vs. the normal manifold that is on the GT? More Power or something? The headers I see look as if all four pipes extend down further and then go into one pipe, where as mine converge into two pipes instead of staying separate and then down to one.
 

·
Member
Joined
·
315 Posts
There are good headers, and there are bad headers. There is one header for the GT on the market that only costs about $150... and it will LOOSE HP. LENK used to make a good 4-2-1 header, but it now costs over $800. The LENK header would make more HP on just about everything, but the pipe diameters are really too big for everything but super HP ("built") engines. Another problem with the LENK header is that it was really designed for use with dual side-draft Webers, so there's bad interference with the stock manifold.

So... what to do... what to do. The low cost answer is to go to a cast manifold from one of the '75 and later FI engines. This will give you a little bit of HP increase. (I don't know how much they go for these days... check with your favorite Opel supplier.) The second answer is a "mid-cost" answer. We make (special order) a 4-2-1 that is "similar" to the LENK", but uses smaller tubes (1 3/8 or 1 1/2 depending on application). It makes better HP than either the FI manifold or LENK for most street applications. It costs $ 420 so I guess "mid-cost" is a relative term. Last, we make a 4-1 header with a "merge" collector. This makes more HP than all the above... but it is expensive $940.... so either you are a racer (and want to win) or you have to be really serious about HP for this one. This header is custom built to match your engine specifications (carb, cam, compression, etc.)
 

·
Life Long Opeler
Joined
·
692 Posts
Discussion Starter #3
Great Answer......Thanks!!!

What to do........??? Hmmm. I know. My birthday is in May. You could give me............. ;) Just kidding. (not really)

Well, my brother-in-law builds race cars, has a pipe bender, a welder, and owns an Opel GT. Think there is some potential here? I'm going to call and see if he can make me a pair. (Fat chance, but it's worth a call)
 
  • Like
Reactions: The Cub

·
Member
Joined
·
315 Posts
Not knowing what you will end up with for an engine, here is my recommendation on what to have your brother-in-law build for your birthday. First, a 4-1 with a Burns stainless steel merge collector http://www.burnsstainless.com/MergeCollectors/mergecollectors.html Use the burns computer program to determine the correct dimensions of the collector ... the computer program is free when you buy a merge collector. (you did say it was your birthday)

The primary tubes should probably be 1 3/8" tubes... that will give you the best all around street performance. Go to 1 1/2" tubes for more top end HP (above 5000 RPM). The primary tubes should be 36" long... now here's an important part... all tubes should be (within 1/2" max) the same length.

And since it's your birthday, a two stage header would be really "trick". The first section of primary should be 1 3/8" tubes about 18" long (all 4 the same again), and the second section of the primary should be 1 1/2" tubes about 15" long. If you "build" your engine, increase the diameters one tube size.

The diameters and lengths biven here will vary a little from engine to engine, and according to engine specs (carb, cam, valves, porting, etc), but this will work well 95% of the time on 95% of the engines. For all out racing, contact me.

By the way, I suspect that Rally Bob may have a little bit different numbers that are valid. That's the way it is with engine builders... different folks use different "tricks". Hopefully, Rally Bob will give you some more insight.

Happy Birthday:D
 

·
Life Long Opeler
Joined
·
692 Posts
Discussion Starter #5 (Edited)
e-mail the link

Hey, thanks so so so much!!! I see you're an engineer. Thats what my brother-in-law does too. I swear...you engineers and racing. Here's his site. http://www.psci.net/hughes/

I couldnt get that link to work. Could you e-mail me the link?

[email protected]

Thanks
 

·
Member
Joined
·
315 Posts
I forgot to put it in the last post... the Burns site has a number of good tech articles that explain the principals of header design. Check out: http://www.burnsstainless.com/TechArticles/Theory/theory.html

If you're really into this stuff and an engineer, buy the book they recommend: ‘The Scientific Design of Exhaust and Intake Systems' by Phillip H. Smith’. It is the best book on the subject I have ever read. I think most of the Burns "computer program" formulas probably came from this book. If you're a programmer type you could probably write your own program from this book.
 

·
Life Long Opeler
Joined
·
692 Posts
Discussion Starter #8
Perfect!!!! Thanks a lot

My bro-in-law is racing in Bristol, TN this weekend. Actually going up against the daughter of John Force in Super Comp series. This hour....... Holy cow!!!!

I'll talk to him on Monday and send him to this site. Ity's perfect!!! Thanks again for your help.

If I had the money, I'd just buy some from you, but I have a laundry list of things I need to get just to get my car road worthy again. You know how it is!!!
 

·
Member
Joined
·
315 Posts
The reality is that our "full tilt" header is not worth the money to anyone but a full tilt "racer" or some one who is a fanatic, with too much money and has bought everything else that can be bought. Spend your money on building a sound reliable engine. And if your brother-in-law doesn't "fess-up" for your birthday this year, maybe your wife will next year... that is if you're not sleeping with your Opel by next year:D
 

·
Administrator
Joined
·
10,080 Posts
TGSI Racing said:
Sorry about the link... I don't know how to fix it up, but I'm sure Garry "the wizard" will get it fixed. In the mean time here is the base link to the Burns site: http://www.burnsstainless.com/index.htm

Give that a try

There was a period at the end of the link that confused the browsers. All set now. ;)
 
1 - 10 of 10 Posts
Top