There are a number of ways this could be done. For clarity, I'm not talking about a 3-stage setup using small, medium, and large turbos.

Rather, I'm talking about using two small secondary turbos and a traditionally large primary like a K31, Ht3b, GT4202, etc.

The biggest and most obvious drawback is that it would require a custom manifold be fabbed. You'd essentially have two separate manifolds each connecting to three cylinders. So this is a challenge.

Another challenge is the packaging. The most obvious packaging challenge I see is the oil filter location, which could easily be relocated using a dual remote setup like Amsoil sells.

Why would a person want to consider a system like this, with all the added complexity?

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I have to think that fabbing two smaller 3cyl manifolds is much simpler than fabbing one larger 6cyl manifold that has to feed a T3 or T4 flange.


We previously mentioned something about this in passing (I think it was Artsi_L's thread about "two small turbos better than one big one?").

But I didn't realize that the small turbos were so affordable and so compact-- both of which make this much more doable than I previously estimated.

This is beyond the fabrication skill many of us have available or within budget.

But to those who aren't in that situation, it might be an intriguing option to pursue.



As a P.S., I'll add the BMW is doing two small parallel turbos on its 300hp 3.2L I-6. There must be some merit to the dos ninos, imo

Justin

 

I did this on a pulling tractor I used two to4 as primary's and a large I think s400 for the secondary its been awhile at 160 lbs of boost it put the crank on the ground however in that situation triviality wasn't important. I if I can Scan the pics Ill post them.

 

I thought about doing this when i was building my custom header at the time i had a couple smaller wastgated turbos they were a/r 's ... i would think it would work very well especialy for a tow rig .... i think it would be pretty tight on a 2nd gen ... 1st gens have alot more room ...

 

would 2 3bt manifolds work? i think they made a 3bt, i have seen a 12v in a ranger with 2 hx 35's and a mondo supercharger.

 

Yeah, hohn's post got me thinking of that ranger too.

 

woodruff diesel built a set of triples for someone i think it is still on their website

 

yup, I just checked their site out. Its still on there, and looks like they'll still build a set for anyone that wants them.

 

The Woodruff kit is very different than what I had in mind. Those turbos are WAY too big to be small secondaries.

Instead, I think they are doing dual PRIMARIES with a stock sized secondary.

IMO, that's backwards.

jmo

 

Too tired to type it all up tonight, but I've got some things to say and I'll be back in about 8 hours to say 'em

 

I still like the supercharger and twin turbo idea.

 

Bracing of the manifold seems like it would be an issue. If what I'm visualizing is correct, each manifold (which only bolts to 3 of the cylinders, correct?) is being asked to hold two turbos. Some serious bracing would be required, otherwise I would venture a guess to say we could actually rip the studs/bolts out of the head.

I say that, because I'm not sure if we use studs or bolts on our trucks. Haven't had the pleasure of dropping one.....yet.

Next, how would the exhaust be routed? Two smaller turbos would be feeding the big guy, but wouldn't the exhaust pulses from each turbo fight each other? Path of least resistance, yada yada yada. The factory puts a divider in the manifold for a reason....So fabbing one of those into your hot pipes would be a must.

That's all I've got for now. I'll be back in a few cups of coffee.

 

Justin, didn't the BMW system feed the small turbo first then everything else went to the second, larger turbo?

 

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i dont think it would pulse to bad it would be devided into 3cyl just like the stock manifold,and wouldent the pulses help spool up the primary. when we buy aftermarket manifolds they are a pulse design. but im no turbo wizard

 

Would a blower not work better than a turbo

 

You could use eg 2 GT2259 as secondaries, mounting them in a way that the front one has the compressor to the front, the rear one to the back, with the manifold facing slightly upwards, so that the turbos sit a little higher than the stock HX35-
Since the turbine exhausts meet in the center of the head you could use a 90deg downward neck on each one to enter into a divided housing. This should place the primary almost into stock position.
I will have to look into that since at my altitude the spoolup with a tight TC isn't too nice and I would love to have quicker spool and just enough air up in the revs.

Just my 2c

AlpineRAM