XLR8R

Why is no oil pressure on startup a problem in a Garrett BB turbo? They don't require a hydrodynamic film to spin on like a journal bearing needs - besides, I know oil restrictors are supposed to be used with the BBs for high pressure oil pumps like the CTD has.

Even so, an Accusump (or hydraulic accumulator equivalent) could be easily used to fill the Garrett's bearings with oil prior to startup....

HOHN

I'm not even sure that it *IS* a concern-- just that I read something about oil pressure wrt BB turbos.

Garrett addresses this issue on their website, so I suspect that it was perhaps an issue once upon a time, but no longer is. Garrett seems to be trying to make the point that it's not a concern for their turbos.

As for Turbonetics and others, I have no idea. Garretts seem to have a pretty decent reliability record, and even die hard Turbonetics and Precison fans often acknowledge that Garrett is the leader and primary innovator in turbos.

The accumulator would be an easy fix, but I don't think it's even needed.

BB turbos don't need hydrodynamic film, but they DO need oil.


Apparently, they also need the water cooling, because there's so little oil flowing that the oil provides little to no cooling.

JH

Mike Holmen

Hohn, have you spent any time investigating if the holset VG turbo would work in your fantasy twin set-up? How where you planning on setting up your wastegates? Both have turbos have internal wastegates. I wanted bigger garretts 42 and 45 series set-up. The cost and durablity issue turned me off.

Tiger Rag

Hohn, just an observance from another side of things, what are the economics of a set up like you are theorizing? I've never looked deep into the Garrett turbo's but my perception is that they are a little on the pricey side. Just for the 2 turbo's from Garrett, what would you expect to spend on them? I know there are a lot of other considerations with the plumbing, wastegating, and your water to air intercooler, but I was just curious on the turbo's themselves.....ballpark? I like the idea of trying something new to see if you could greatly improve on traditional compound turbo setups. I guess my only fear is that you could spend twice the traditional setups, not to mention the headache of getting the plumbing right. You'd definitely have to have your PHD in patience in a new and untried setup in my opinion. Might be worth it once you get it ironed out though. I also like your nothing ventured, nothing gained process of innovating a new setup. I hope you are able to make it happen. Good luck, Matt

signature600

Well, the GT3788R kit is around $2000 IIRC...I might be a bit low!

A GT4088R can be had for under that if you want to go larger...but more custom!

A GT4202R will be around $2500

A GT4508 will be just under $3000...I have about $300 in mine which is just a CHRA!

Chris

RowJ

Just a quick question for Justin!
What's a 02.9 CTD? Noticed your signature and am not familiar with this model?
Heck, I may have one and not even know it!

RJ

HOHN

It's just a reference to that late build- July 2002. My truck was built within the last two weeks of the 02 production run. It was built at that mexican plant that they close after the 2nd gen run, so it was one of the last at that plant...

HOHN

I'm not aware of any VG controller that I could adapt to this application, or a VGT would be at the top of the list. Most VGTs are ecm-controlled, and I have no idea how to adapt that to an application where it wasn't factory.

Perhaps Banks could shed some light on it for me? Wasn't it an HY55 VGT they used on the Sidewinder Dakota?

Durability of the BB setup doesn't worry me all that much.

But dang are they expensive!

NoSeeUm

A supercharger would be nice for fast boost build-up. If it could efficiently get out of the way at higher flows and boosts.

Keep in mind that at the flow and pressure Hohn has in mind that the compressor(s) alone (just off the top of my head) would require some where in the neighborhood of 250-300 Hp. With a turbo system, as long as the drive pressure ratio stays around 1.0, this Hp comes virtually free to the engine. A blower would require this same if not more Hp as it runs at a lower efficiencty. Which means Hohn would have to increase his boost number to get the same net engine Hp. That would require still higher blower Hp. The engine would burn 250 - 350 Hp more in fuel to reach 500 Hp than if the engine were turbocharged. A vicoius circle at best to that route only if you care about fuel economy.

Three things you have not really calculated Hohn, IMO.

1) 500 Hp @ 2000 rpm @ what EGT? Might be a shame to buy it, build it, test it, and have it not perform. For towing, EGT is king.

2) At 500 Hp steady state the engines cooling system is undersized on its own. Throw in a CAC that is dumping allot of heat in front of your radiator and the problem gets worse. The air to water CIC will add still more heat load. You need to calculate a heat balance to properly size your cooling system. A second or larger single radiator, the cooling fan flow requirements and possibly a larger water pump.

3) What are you going to find to tow that needs 500 Hp?

The Garret stuff seems very exciting.

Jim