Is there a larger "center mount" turbo available??

[7.4 VORTEC]

Good Day All,

Is there a larger and or better turbo to replace the stock unit on the center mount trucks (like the 6.5TD vans and Hummers)? Are there "stock" turbos that have updated or better bearings, vanes, etc. Anyone actually blueprint these things commercially?

Any info anyone can throw my way would be appreciated. Big problem I have is the high rpms my truck cruises at. Added other power boosters (re-programmed ecu, intercooler, exhaust, etc) seem to work well on the 6.5 at pick up truck rpms, but not as efficient in the 2500 to 2800 rpm range with the stock turbo.

Thanks,
George

[Robyn]

There are no GM updates but one can get creative and adapt other turbos to the task at hand.

Someone will chime in here soon and give you some advice as to what might be the best choice.

Robyn

[j_k_auto]

The only thing I can ad to this is the best gm stock turbo is a gm 8. That is the newest design for the 6.5 if I am correct. It flows better on the exhaust side.

[7.4 VORTEC]

Silly question, is the center mount GM unit also a GM-8?? I was hoping someone had an idea of a turbo that could be "swapped" in with minor mods to provide a little more airflow at the higher rpms I cruise at.

I've got friends with the 7.3 powerstroke that have soooo many options, it makes me jelous. One of them is building up a monster 7.3 PS. He actually had one side of the turbo ceramic coated and the other side polished (for looks). The ceramic coated side was suppose to help keep the heat in and the turbo rpms spun up. I'll find out which side he had ceramic coated (I'm assuming the exhaust side)

Cheers,
George

[j_k_auto]

I was doing my normal searching around and did see that some guys used a hy35 and a hx 35. They are starting to pop up more and more.

[7.4 VORTEC]

Thanks J K Auto,

Do you have a brand name to look under? I'll google the models you listed.

Any other info would be appreciated.

Cheers,
George

[1999GMC]

HX and HY's are Holeset turbos. They run them in the Dodges with the Cummins.

[john8662]

There are no upgrades tried for the center mount turbos found on vans and Hummers.


This turbo is a GM-6 turbo, the GM-8 is for C/K chassis with the turbo mounted on the passenger's side of the engine.


But, as most things go, it's always possible to upgrade the turbo back there with some creative adapting.


I've often thought that the turbo and related hardware could be removed from one of these engines and another Turbo flange welded onto a 3" Y pipe so that you could then plumb the rest of the exhaust around and have a custom turbo setup...

So, Hummer or Van?


J

[7.4 VORTEC]

1999 H1 Hummer with the 6.5TD

Big problem is the gearing and the constant high rpm which I feel falls outside the stock turbos effeciency "sweet spot" can really can create higher IAT's, etc. The high IAT's don't help the engine temps either. If I'm towing in overdrive at 60 to 65 mph is 2500 or more rpm. Thats with 37" tall tires! Kinda rpm high compared to the pickups with the same engine and transmission. The drop down portal axles almost doubles the final gear ratio.

Is there anything that can be done to a stock turbo to make it more efficient, run cooler, etc. Bearings, changing vanes, etc?? I'll have to start looking at some of the holeset units and see what it takes to match them up.

Thanks,
George

[DA BIG ONE]

RJ has an ongoing turbo project that gets bumped back to front page of this forum. Perhaps, he can update us on this and comment on a retro for rear mounted unit too?

The GM-8 is ok within its limited range, we all need an upgrade that will work.

[john8662]

1999 Hummer H1?

I've thought up a solution for you guys with the rear mounted turbo.

Banks had an aftermarket Turbo Kit for the H1 Hummers with the 6.5 in them from 94-95 when they were NON-Turbo Models.

This setup ain't bad at all, it mounts a turbo under the hood similar to the way that the truck's had the turbo mounted.

This would give you the ability to adapt any turbo to your engine, including a turbo that RJ is working on. It comes Standard with an MHI-TE06H wastegated turbo already, which by itself is an Improvment over the BW turbo on it now.

I don't really mean to alarm but the rear mounted turbo setup used on 6.5's is a large contributor to why those engines fail in ways the truck engines don't see.

Things like cracked cylinder walls on the back cylinders, head bolt holes cracking into the bores and in turn blowing the head gasket.

In reality, there is just TOO much heat back in that part of the engine. The truck 6.5 already has cooling problems at the rear of the engine. I've measured the different between temps on the back of the engine verses the front. What I found is that there really IS a cooling problem that made GM allow for more cylinder to bore clearance back there. This range swings between 10 - 15 degrees hotter, depending on whether the thermostat is open or not.

Add exhaust routing on the back of the heads in an already too hot zone, and put the turbo in the HOTTEST portion of any "V" engine, in the valley, and you got the recipe for crispy 6.5L.

The problem with the GM-X turbo's is the

1) Tiny Exhaust housing and Turbine Wheel

2) inefficient compressor wheel.

There is a distinct reason why Cummins and Powerstroke engines are way more powerful and durable than the 6.5, they have an appropriatly sized turbocharger.

Take away the Holset off the Cummins engine and you have an engine that can't make the power the 6.2 makes. It's the turbo.

Put that same or similar turbo on a 6.2, and you have a nice combination (with intercooler).

RJ has made comments of the benefits of his Hybrid Holset in the positive, and his results from the previous year's pull off speak for that fact.

Anyways, back to H1.

This is really your main option, adapt another setup.

I've got this very setup on hand, so pictures can be taken. I'll see about scrounging up some images of an installed setup I downloaded a year ago when I first knew of the setup.

You could potentially adapt this setup to your existing heads, etc.

But, I'd recommend changing to the truck heads, and intake manifold.

Surely, if you can afford an H1, you can afford a different turbo setup ;)

late

J

[7.4 VORTEC]

Thanks for the info on the Banks system...I don't think they make it anymore but I'll check. You do see them pop up for sale on ebay, etc. Most hummer owners that had it on the previous generation trucks had positive comments on them. Since my truck is a total OBDII compliant system, I'd really like to get away from the pdm, etc and go entirely with a mechanical injection system.

Actually, the Hummer is one of my least expensive buys of late. Most people don't realize that you can by a 1999-2002 H1 Hummer wagon for less than a fully loaded Dodge Caravan minivan. I gotta tell you, the difference between driving a Hummer H1 and a minivan is like the difference between being Arnold versus Pee Wee Herman. I own a built Jeep Scrambler, a built up Suburban with way too much done to it, a 05 Excursion 6.0 and an 07' F350 Crewcab with a 6.0. Everything is 4wd and the absolute funnest truck is the Hummer. Thats why I'm spending so much time researching upgrades, etc. With another 75 reliable horsepower, this thing would be sooo much fun.

Interesting point you made about the heat differential from front to back. I have friends that have measured a 20 degree difference. I honestly didn't think that was enough to matter. I do feel that since we don't have intercoolers on Hummers (stock, at least) that the small and ineffecient turbo really shoots up the IAT's a ton (I've monitored it with my Scangauge while driving). This in turn is really causing the engine to run warm. Add to that the crappy cooling stack and radiator fan setup and you've got a recipe for disaster. With a better turbo and some sort of intercooling, I think that the Hummer would actually run cooler, even with the center mount issue. The truck has a lot of parasitic drag due to the aerodynamics (a brick is probably better), the portal axles, aggressive tires, etc. When coming off the freeway, you can pretty much coast to the stop sign at the end of the off ramp, often times without having to use your brakes. Imagine downshifting from OD, to 2nd, to 1st with a 6.5TD pickup....thats what the Hummer feels like just coasting in OD.

Lastly, I do think there is enough market demand from the 6.5TD guys (mainly pickup guys) to warrant a manufacturer looking a an upgraded turbo for the 6.5's. Obviously it's an engine that has a very devout following. Maybe an existing turbo can be made to work with some sort of an "adapter kit" that will allow for a more bolt in replacement. Who do we start bothering to have them look at this potential market segment.

If you want to post any pics of your setup, that would be cool.

Thanks again,
George