4" Downpipe & Exhaust, any such animal 4 the 6.5td?

[DA BIG ONE]

See some statements that people are running 4" turbo/back systems on 6.5td's. I can't find anything other than 3" downpipe w/transition to 4" back, any full 4" systems out there, or?

[dieseldummy]

I don't think that anyone manufactures bigger than 3" for the down pipe then 4" the rest of the way. I built my own out of 3.5" mandrel bends, I personally don't see 4" fitting without major rubbing. My 3.5" is bad enough.

[DennisG01]

Ditto what DD said above - actually I'm surprised he even got a 3.5" downpipe to fit! 3" downpipe is pretty much the standard. I wonder if a bigger downpipe would even show any legitimate gains? The biggest factor is probably having the pipes mandrel bent.

[DA BIG ONE]

I'm diggin deep into this and going to somehow fab an oval 4" downpipe to clear chassis and motor. I already have a 3" inside diameter turbine housing connector for a downpipe and thinking a 3" round to 4" oval transition will work using oval pipe for downpipe then back to a 4" round outlet for rest of exhaust.

What I'm seeing is restriction at turbine housing going to outlet, porting and a larger 4" diameter downpipe would work wonders for the 6.5td.

The following link will give ya an idea of parts that can be used.
http://www.spintechmufflers.com/spintech/spintechindex.asp

[Bnave95]

Getting the bends in it for a down pipe would be interesting:)
Can they be bent? Maybe by getting the pipe cherry red where the bend needs to be?

[dieseldummy]

IMO, 3" is plenty big enough with the GM turbo. No matter what it is still the biggest restriction in the system. Bigger can't hurt though. Another thing to consider is how well does oval tubing flow?

[Bnave95]

I say use the oval pipes for running boards and EX. into them. Now that's COOL! Slash cut the ends. NASCAR style:)

[DA BIG ONE]

IMO, 3" is plenty big enough with the GM turbo. No matter what it is still the biggest restriction in the system. Bigger can't hurt though. Another thing to consider is how well does oval tubing flow?

Been thinking about the oval tube flow and thinking it's a non issue on a turbo motor that likes rapid expansion of gasses after turbine a 3" 14ga pipe has 6.33 sq inches, a 4" 16ga pipe has 11.76 sq inches.

The cost of the oval & bent tubes is excessive so thinking of splitting a downpipe and welding in flat panels to make it oval.

[stingthieves]

I already have a 3" inside diameter turbine housing connector for a downpipe and thinking a 3" round to 4" oval transition will work using oval pipe for downpipe then back to a 4" round outlet for rest of exhaust.

Building an Oval Downpipe that is. Does that mean you will be using the new downpipe you just got? Thats ok - Ill just stop anguishing for the UPS man to stop at my door with it! Rick

[DA BIG ONE]

Building an Oval Downpipe that is. Does that mean you will be using the new downpipe you just got? Thats ok - Ill just stop anguishing for the UPS man to stop at my door with it! Rick

NOPE, That pipe is different and yours, however, after checking it's sitting all packed up for shipping in the back of my son's truck when it is supposed to be on it's way to you, SORRY!