Reverse rotation turbos

I have been brainstorming a twin turbo V8 for years and it has always driven me nuts that the turbos just don't "fit".

Notice that the turbos don't fit symmetrically in the engine bay due to being identical instead of mirror image. Just today I found out that reverse rotation turbos do exist, I just don't have a clue where to get them. Anyone here have ideas for GRM sources for a turbo and its mirror image counterpart?

The new Powerstroke has sort of a reverse rotation turbo. It has two compressors (and two turbines) on the same shaft. The compressors are back to back and are mirror images of each other. The inlet for one is on the bearing side.

Not helpful in the least, but it's full of awesome.

I can't help you any (no surprise, huh?) but that is an incredibly good looking engine bay shot. Wow! What kind of car is it?

Ask Garrett. I'll bet they know.

Before Cummins bought Holset they made their own turbos that were reverse rotation. Pre-75 or so. They just don't have the nice geometry of today.

They made these backwards beasts because they didn't want someone going to the store and replacing the unit with a competitors unit. You could do it, but there would be a bunch of piping work.

Now... There are two brother turbos, currently made by Cummins Turbo Technologies. One is a BHT3B and the other is a HT3B. One is a reverse rotation modern equivalent to the old "cummins turbo" One is just a normal rotation turbo. I cannot remember which is which is which.

They are big.

edit: btw.. They're really big. I just want make that clear.

Only ones I've seen are from Nelson Racing Engines. They have machined-billet symmetrical housings as seen on their "Sano" 1984 Camaro:

And on a big block chebby:

I can't begin to imagine what they would cost you, though...

Seems like a lot of trouble and expense, never mind the very limited offerings, likely forcing the use of inappropriate-sized housings. Then there's trying to get it serviced; what happens if the one and only source of these goes away? Doesn't seem worth it just to get "mad propz" at car shows.

In reply to kb58:

yup, that is cubic dollars to fix a purely aesthetic problem.

It isn't always purely aesthetic. Look at the routing the intercooler tubing will have to follow in the first pic compared to the routing with the nelson racing engine. There are many occasions where flipped outlet would make things easier and the flow path much less complicated.

Iggy-How big?

Edit-found it. 5" exhaust outlet.

How about BMW's current N63 twin-turbo V8 with the turbos mounted in the V? V8 pics Not symmetrical but all the "ugly" stuff is hidden when the motor is fully dressed.

what about forward facing outlets, still not symmetrical but you can get the flow path out from the turbo symmetrical by clocking the housing...

The engine compartment isn't symmetrical, you have only 1 alternator, a steering shaft and usually AC compressors and brake boosters sitting in there. All of them will make you compromise the inter cooler piping.

This is Nelson's signature...these are more than just show car engines too, their engines make some serious power. Fantastic craftsmanship, but you pay for it!!!

Bryce

problemaddict wrote:

Does this look like Cthulhu to anyone else?

ReverendDexter wrote: Does this look like Cthulhu to anyone else?

Knurled wrote: The new Powerstroke has sort of a reverse rotation turbo. It has two compressors (and two turbines) on the same shaft. The compressors are back to back and are mirror images of each other. The inlet for one is on the bearing side. Not helpful in the least, but it's full of awesome.

Actually it only has one turbine (and it is a standard turbine wheel, not double-sided like the compressor wheel). It does have two turbine inlets (one from each bank) but they drive the same wheel, resulting in a slight increase in efficiency over a single inlet and easier packaging/service in the truck (you don't have to remove the cab to remove the turbo).

Another crazy thing on the new Powerstroke turbo is that it has a wastegate as well as a variable geometry turbine. It's the only turbo Garrett makes that has that, I believe.

Garrett has many reverse rotation turbos, but those were only done for packaging purposes for OEM applications. I don't know if there's a list available to the public that would identify a reverse rotation turbo. I can't remember off the top of my head what letter in a Garrett ID number corresponds to reverse rotation (ex in a GT2860RS, the r = ball bearing) but if I remember I'll look it up when I get home tonight, that could make your search easier if you ever decide to turbo a V8 (and I strongly hope you do - that would kick ass). I don't know much about other manufacturers, but I'm guessing they are probably the same, with only doing reverse rotation for packaging reasons. I also have no idea how the "standard" rotation was originally chosen or why it became the standard.

Bob

let me get this straight ,, you would spend around $5000. just to make it look right,, you must be loaded.

Nissan 300ZX TT used a pair of T-22 that were different, not sure if they are mirrors though. If so, maybe get 4 of them, two on each bank?