Does anyone make a good 4” turbo back turbo exhaust?

[TOBASH]

Does anyone make a good 4 inch exhaust extending from the turbo charger all the way back?

If not, has anyone made one and does anyone have any tips regarding routing of the pipes?

Finally, does anyone have a good source for stainless steel 4 inch tubing with mandrel bent 90 and 45° and 180° bends suitable for TIG welding?

This would not be for the ECV I just purchased. This would actually be for my civilian unit with a P 400

 

[Mogman]

I would be surprised, that motor does not flow nearly enough to require a 4" exhaust, it would be for looks only with no practical application.
EDIT, I did the Duramax conversion with a 3" and the ECM is very happy with it, nearly matching the factory 3 1/2" but without all the "other" stuff in line.

 

[Karl kostman]

Tobash have you modded the engine in ways that your thing it could actually need a 4" exhaust? If stock that engine was just plain happy as a clam with 3" tubing. If your just doing it to be cool then just cut the existing pipe and weld you bigger pipe to that.

 

[TOBASH]

If you guys don't know or don't have a source, then please don't comment.

I don't need snide remarks

 

[Maxjeep1]

Summit Racing, Jeg’s and other places online have builder kits and v-bands and whatever else you need. Google exhaust tubing kits and you will have many options.

 

[diesel_dave]

Just a useless anecdote but I put a 4" on my 95 6.5 pickup when I was a kid and I felt like it did do at least a little something to help the responsiveness and it definitely sounded 100x better than the factory exhaust. I didn't dyno it or anything to prove it made a difference but it definitely felt a little more powerful. The factory exhaust on the pickups was god awful though so probably not an apples to apples comparison but if you want to do it, definitely go for it!

 

[Mogman]

I'm sorry, one of the first things I learned about this forum is if you do not want comments do not post, you BTW make snide remarks all the time!
A 4" exhaust takes up MUCH more room than a 3" on a vehicle that does not have enough "room" as it is, you cannot expect folks not to comment on the absurd.
And yes DD to a teenager louder means faster, actually still does at 64 LOL

 

[TOBASH]

On the civilian units there are several 4" advocates on other sites like The Hummer NetworkForums and TruckStop. I know some of these guys, and on the P400's with turbos they swear that there are significant benefits. I am NOT looking to place a 4 inch on my ECV or A0.

Regarding the overpriced 4" units I have seen, I would prefer to use a TIG welder to make my exhaust rather than spend.

RubberDuck has a 3 1/2 inch unit and feels the 4" takes up too much space BUT Uvora makes a 4" that fits BUT has clamp loosening issues. Uvora is too pricy. RubberDuck units are affordable. My vehicle has a 2" lift to offset some of the clearance concerns.

The engine I will be placing willbe a turbocharged P400 with water/meth injection I am replacing the Whipple Supercharged 6.5 with a brand new p400 at some point, so I need to collect parts and such for the swap.

Mogman... I would be interested to know more about your 6 speed tranny swap

As far as your comments Mogman, I posted here to get additional feedback from DIY'ers like you. Hummer H1 forums have many members who prefer to just send their vehicles out to be worked on rather that DIY. I like and respect your opinions BUT anythingliked by "springer1981" is suspect. Sadly, he and I are not "fans".

 

[Mogman]

I am curious, does your OEM engine have a DB2 (mechanical) or a DB4 (PMD) IP pump?
The P400 is just a GEP turbo with 12V dress, not sure which IP they normally come with, I would assume the DB4.
As I understand the only real difference is the DB4 was required to meet emission standards, all the ECM does is control timing if my sources are correct.
That Whipple 6.5L should make more HP with lower EGTs than the P400 turbo if it can stay together.

 

[TOBASH]

There are some other interesting differences about the P400. The underside has an integrated ladder cage that prevents flexing under high stress situations. I’m told that the alloy is also slightly different (more nickel) and I’m told that the cooling jackets in the heads are also slightly different.

GEP blocks kick ass. Don’t get me wrong.

My 1995 Hummer H1 truck thankfully has DB2.

 

[Maxjeep1]

There are some other interesting differences about the P400. The underside has an integrated ladder cage that prevents flexing under high stress situations. I’m told that the alloy is also slightly different (more nickel) and I’m told that the cooling jackets in the heads are also slightly different.

GEP blocks kick ass. Don’t get me wrong.

My 1995 Hummer H1 truck thankfully has DB2.View attachment 864614

1995 didn’t come with a turbo. I thought 96 was the first year for the turbo? I’m probably not remembering right. I was looking for one awhile back. Maybe 1995 was the first year? Hahaha I can’t remember what I had for breakfast

 

[TOBASH]

1995 didn’t come with a turbo. I thought 96 was the first year for the turbo? I’m probably not remembering right. I was looking for one awhile back. Maybe 1995 was the first year? Hahaha I can’t remember what I had for breakfast

CORECT, this P400 is new to the truck. That is why I am getting ready for the exhaust system now.

The P400 is a purchase to replace the original engine. I need to adapt and bend pieces for the lower oil pan and rearward turbo. While I'm at it I will place a new rear exhaust.

 

[Mogman]

All GEP engines have the high nickle block and heads as well as beefed up main gurdles and main caps, cannot speak of the rest, I have asked the factory for clarification.

 

[Maxjeep1]

All GEP engines have the high nickle block and heads as well as beefed up main gurdles and main caps, cannot speak of the rest, I have asked the factory for clarification.

P400 has a flat oil pan and the bottom of the block is reinforced compared to others. It’s the most robust option I believe.

 

[Mogman]

P400 has a flat oil pan and the bottom of the block is reinforced compared to others. It’s the most robust option I believe.

I think you are pretty correct here is the response I got from 6-5Liter dot com.
Hi Craig,
The P400 is/was made by GEP for the up-armored HMMWV variants.

The only difference between the P400 and regular Optimizer engine is the added girdle on the bottom end.
Thank You,
Jeff Aiello
Bostic Motors Inc.


It seemed to be he is saying the HMMWV is a P400, I will see if I can get clarification

 

[MattNC]

I just finished the BMI kit matched up to the bowtie 700r4. The exhaust routing is something I’ll fix in the future but the 3” pipes with the turned up DB2 is about as fast as I want! Definitely hitting the limits of a flying brick! 70 mph on the highway makes me feel like Jeff Bezos shooting into orbit. I have aftermarket wheels and nitto ridge grapplers and my next mod is going to be getting the camber and caster dialed in to make the steering a little less touchy at speed.

I guess what I’m saying is my experience so far the turbo with 3” pipes is plenty happy. It really flies now and on hills pulling third gear just before the upshift it’s at 11psi with the waste gate open and 825F on the egt. I think the exhaust is flowing just fine at 3”. And I spent a ton of time looking where in the world a better route for the exhaust is and I do think 4” would not only be a challenge, but also will be tough to give enough space so it doesn’t cook the other lines present.

All that said we live in the land of the free and I won’t shoot any negativity on your plans!

 

[patracy]

Not a snide remark, but just sharing some advice. A single 3" exhaust will flow ~750cfm alone. That can support 350hp no problem.

My experience with diesels in general has been that the exhaust diameter really doesn't matter provided that there's nothing to impede the flow. I had ran a 5.9 cummins for a while with nothing more than a 3" glasspack over the stock exhaust (minus the cat). I went up to a 5" exhaust. Because everyone was. It spooled slower after that. And with the exhaust I gained only 3hp on the top end. Now it did make sense later on when I went to a different turbo setup and even larger injectors. But even with just fueling added to stock injectors it did nothing. Apples to oranges comparison but something to consider.

I have a BMI turbo setup on my HMMWV. I changed how the exhaust was routed, but still kept it at 3" diameter. My EGTs are just fine. I can't give a before/after of course. But I also have a 6.5 turbo setup on my CUCV. I've only got a 3" exhaust there as well. Again with only ~200hp or so, there's not much to gain.

I would however completely agree with changing the muffler for a straight through/open design. Outside of that I think you're going to end up having to weld up your own exhaust.

 

[Maxjeep1]

I would do a 3.5” if I was building one for my m1165 and ditch the muffler and anything else that restricts. 3.5” should make everyone happy! Lol

 

[Mogman]

The P400 is easy enough to spot, never seen one in a HMMWV although BMI says some up armored trucks got them, the only difference is the girdle, guess I will have to take my chances with a plain ol GEP turbo, BMI says you can't get to the power level that would require a girdle with the DB2 pump anyway.

 

[MattNC]

has anybody run a turbo and straight piped it with no exhaust? Is it annoyingly loud?