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1 7/8 header to big on 408

5K views 19 replies 8 participants last post by  TWNWHR 
#1 ·
gonna be making my turbo exhaust. are 1 7/8 to big or just right? it's going on a fordstrokers dart 408 9.0.1comp w/ afr 225 58cc and bw480s turbo. looking to make 900+ rwhp through a th400. gonna have dual tial mvs 38mm wastegates, 83lbs, super vic efi, accufab 4 barrel throttlebody and prob a/w under dash intercooler. all this on a aem ems. what size cross pipe should i run 2 1/2'', 3''?
 
#5 ·
i got a box of 1 7/8''mistake bent tubes, header flanges and collectors for $365 shipped to my house from stahl. i think i can't go wrong for that price
 
#6 ·
A 15/8 header on AFR225 exhaust port dont think that is gone to work real well. I would put no smaller pipe then the port size. But thats me.
 
#8 ·
X2 on that..

I read a very long thread on Yellowbullet and the consensus by people smarter and more experienced than I is that you want to run a header primary size that would be the minimum for what you'd want naturally aspirated. On your combo, Id say about 1-3/4", but you got a deal on 1-7/8" pipe, that'll probably be just fine.
Primary size should match the port size. Id be curious to see the drive pressure and reversion that was going on in Snipes TFS-R heads with 1-5/8" headers.

As for the cross over, Id probably stick to 2-1/2. You can get to a pretty high power level with that. Depends on the radius of your bends too though and how youre placing the turbo.

The concern I see is the S480. A 408 is pretty big for that turbo, I hope you have a large turbine and a large A/R. You may want to step up those 38mm W/G's to something larger or you may run into drive pressure/over speed issues..

Just my .02, but I only know what Ive read.. Id be real interested in seeing how it works out. Good luck!
 
#7 ·
I had TFS TW-R heads with a ton of work to them and huge ports. I insisted that I needed headers with tubes big enough to clear them but no one at the time made any off the shelf ones. Finally after I talked to some very experience and reputable turbo kit builders I opted for 1 5/8 like they said would work. That car with a 347 made around 1200fwhp which also was the limit of the turbos and fuel system.
 
#10 ·
Didn't say they would not work just. Just not what I would do the exhaust hits a big enough block when it hits the turbo.
 
#9 ·
Actually.. I just remembered you can get two turbine wheels (that I know of) on the S480, an 83mm or a 96mm... Do you know which you have?

The 96mm would probably work out ok..
 
#13 ·
^^^ agreed. Understand what you are saying. Just not the way I would do it LOL..
 
#14 ·
i have the 96mm wheel and 1.32 AR. i just hope the twin 38 mvs gates will be enough. this setup should be pretty badass if it comes out like i want it. but it won't be done till nxt season. i plan on making a build thread
 
#20 ·
Sweeeet, Im very curious how this works out. I have a 10 to 1 427 and Id like to put an 88 on it to do some local 275 races.
If you happen remember, shoot me a PM with a link to your build thread, Id really appreciate it.

Good luck!
 
#16 ·
I just had a custom turbo kit built for my car and its a 427W with ported Victor Jr. heads, 9.2:1 and will be running a Precision 101 with 66mm wastegate and its 2 inch primary and 3 inch cross over. Im wanting to make a little more power than 900 though. This is what was said would be best. Id say the 1 3/4 inch would work perfect.
 
#17 ·
my min goal is 900rwhp. hopefully i can break the 4 digits w/o a problem. turbo is good up to 1250hp. so what about x-over pipe. someone said 2 1/2 and another 3. will my 83lbs be enough for 1000hp otherwise i'll have to searching for bigger.
 
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