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Originally posted by Monaroman68

Woz my son is a fabricator by trade so its possible for him to make just need to no what style sizes and lenghts etc , was just looking for a quick fix here thinking someone my have a set of custom pipes to do the job. My engine guy suggested 4 into 1 with 34" primaries at 1"5/8 but i'm herein that that could be to small he also suggested a merge collector like the ones used in nascar usac etc any help would be very appreciated.
Cheers Dave

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I would stay away from 4-1 items full stop. 4-2-1 items done correctly are the way to go in my opinion. There is a small gain in peak H/p using the 4-1, but the sacrifice in low-mid torque is fairly dramatic.

Because I don't know what went into the internals of your engine it is very hard to comment on what you need regarding length and diameter, this is something you would need to trial and error on your engine on a dyno.

There are formulas to calculate runner lengths and diameters, so thats probably a good place to start.

What I can say though is that I have found that being slightly on the small side can work better than being on the large side in alot of cases. And with a 4-2-1 it is very important to collect 1 and 4 together, and 2 and 3 together.

Making your own is time consuming, but if your son is a fabricator you could have a play around. If you're serious about it making the best power (which it sounds like you are) it is well worth the effort though, and done correctly they will last for years.

Woz

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Originally posted by danny m

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Originally posted by Wozzah

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Originally posted by danny m

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Originally posted by Wozzah

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Originally posted by danny m

Hey Warren how large is larger and roughly how long

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Hi Danny,

Off the top of my head:-
4-2-1 design
Primary: 1 5/8" diameter, 17-19" long
Secondary: 1 7/8" diameter, 20-22" long
Outlet: 2"

Cheers
Warren

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That small!
Ick!
I think you guys will find there are no off the shelf pipes period that will allow you to makea genuine 200hp

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As I stated, for of the shelf ones they are the best you will get. I wouldn't call them small, but Agreed on the horsepower, the best I've had out of a set of the pacemakers is 195hp.

If you want any better monaroman, you'll have to have them made.

Woz

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Hey Warren that would be GoPower hp wouldn't it?
Those sizes will strangle you to the mid 170hp to go any more you need to be using an 1&7/8" primary at 15" long


Danny

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That figure is using a chassis dyno with a Motec program which I have been using for years. 128kw (171.52hp) @ wheels. The loss factor calculated (around 12%) equates to around 192hp. My std manual AU XR8 made 151kw on the same dyno.

Regardless of the size, the pacemakers have proven to work very well, and custom made similar configurations have worked equally as well.

Warren

There is a bloke called Gonzo (??) who makes pipes that people seem to rave about. Not sure why his are any better than others though. Wish I had a pipe bender, would rather like to play around and make a set.