Odd Ball TT Question

Gravy · 10-12-2007

Talking at work with a few guys today, one of them asked why i was going to do two larger turbo's on the car, when i could keep one smaller, and one larger so the small spools up quick, and the larger keeps the top end running strong and happy. As i remember something with this set up doesn't allow the set up to work, either the smaller turbo pushes on the larger one making it spool up much slower, or for some reason it doesn't work. I remember getting into this on another forum a long time ago... but now i can't remember what the verdict was.

Could someone help set me straight so this stops bugging me.

**scheides** · 10-13-2007

The smaller turbo becomes a restriction at high rpm and holds back power.

Just slap on two Evo3 16G's and show him what fast is!

turbotalon1g · 10-13-2007

I think that you should just sell the car, or do a SHIT TON OF READING before you touch anything on that car.

Gravy · 10-13-2007

I've done my reading, i know enough about it. But i still plan on going dual 14b's to start, but i couldn't remember there was a reason not to do it. Something mechanically didn't work out.

Something i thought made the set up bad, or impossible. But, this was probably 2-3 years ago, and i hadn't thought twice about it. One 14b is already bought, and the second will be picked up in the months to come. By spring i'll have 14b's, FMIC, 255lph fuel pump, FPR, gm MAF and 450cc injectors. Not looking to put huge numbers down... but i'm gona see what she runs like with some TLC. Along with the regular stuff that needs to be done, should be a nice fun ride when all is said and done. Have to get use to 4k spool up on the 14b's. That's why i started thinking about the larger//smaller set up.

turbotalon1g · 10-13-2007

I am sorry to be mean, but look at the fucking motor and follow the pipes, then just think for a second how they work.
Each turbo works on half of the motor, it is not set up sequential like the (i believe) the stock 3rd gen Rx7s are.
Come on man, i know that not everyone has the same abillity, but you got an awesome platform to begin with don't fuck it up, if not pay the money and let someone else do it. 14bs will spool before 4k.
Did u join 3si yet?

sleepydsm · 10-13-2007

Those cars aren't that great (I'm not saying DSMs are amazing either). And why not just do a big single?

Gravy · 10-14-2007

Quote:

Originally Posted by turbotalon1g

I am sorry to be mean, but look at the fucking motor and follow the pipes, then just think for a second how they work.
Each turbo works on half of the motor, it is not set up sequential like the (i believe) the stock 3rd gen Rx7s are.
Come on man, i know that not everyone has the same abillity, but you got an awesome platform to begin with don't fuck it up, if not pay the money and let someone else do it. 14bs will spool before 4k.
Did u join 3si yet?

I havn't joined, but i visit daily and read what's on there.

For the record, i HAVE looked at the motor. Both turbo's start with their own piping, come into one large pipe going into the intake manifold, then the single boost source, aka everything, goes through the throttle body. Then, the intake is divided between the different runners into the engine. So how is this different then doing a single large set up? Then i'd have one boost source having to feed the motor. Picture should explain my stand point some:

Still going dual 14b's, and i've got a friend doing the welding, and another getting the plates to weld onto the piping for the 14b's. I'm just talking about the IDEA of doing two different sized turbo's. In theory, it should work though.

Most people that have done 14b's actually spool up around 3k or so, but seeing as these come on at around 1.5k rpm's on the DSM's, and your dealing with .5l smaller engine, will take a little while longer.

Andrew7dg · 10-14-2007

Quote:

Originally Posted by turbotalon1g

I am sorry to be mean, but look at the fucking motor and follow the pipes, then just think for a second how they work.
Each turbo works on half of the motor, it is not set up sequential like the (i believe) the stock 3rd gen Rx7s are.

Ha!!

Most of the RX-7s just go to a big single anyway...

Andrew7dg · 10-14-2007

Quote:

Originally Posted by Gravy

I havn't joined, but i visit daily and read what's on there.

For the record, i HAVE looked at the motor. Both turbo's start with their own piping, come into one large pipe going into the intake manifold, then the single boost source, aka everything, goes through the throttle body. Then, the intake is divided between the different runners into the engine. So how is this different then doing a single large set up? Then i'd have one boost source having to feed the motor. Picture should explain my stand point some:

Still going dual 14b's, and i've got a friend doing the welding, and another getting the plates to weld onto the piping for the 14b's. I'm just talking about the IDEA of doing two different sized turbo's. In theory, it should work though.

Most people that have done 14b's actually spool up around 3k or so, but seeing as these come on at around 1.5k rpm's on the DSM's, and your dealing with .5l smaller engine, will take a little while longer.

In theory it should work... It did for the RX-7

However you have 3 cylinders pushing one turbo

If you went to this small/big setup you would have 4 turbos all together, two for each exhaust route

This is unless you went to a big collector in the exhaust to push that one (or two if you want to use the big small setup)

A lot of repiping needs to be done. then figure out where to put the turbos

I don't know if people have done it with 3S... All I know is people usually upgrade the 2 turbos...

Gravy · 10-14-2007

Yeah it would take a lot of work to get it done, i think Aaron is a little mad at me though. Not sure why, i'm just saying in "Theory" it should work. But i was trying to figure out why i thought this would work.

In the new VW Iroc they are, or were, doing a SC and turbo set up. They had an electronically controlled valve from what i read, when the engine was at lower rpm's, and the turbo was making no boost, the SC would push air in to give the engine a boost. Then when the turbo is supplying boost the sc(clutch driven) shuts off, and a one way valve closes. Allowing the turbo to supply the boost. At least that's what i remember from the first release on this long time ago.

curt_gendron · 10-15-2007

On a 3/S, half the engine feeds one turbo and the other half of the engine feeds the other turbo. If you put different sized turbos on each side, the smaller turbo becomes the restriction and you can't run much more boost than what the smaller turbo can handle. If you do, you'll just make the smaller turbo run super hot and not really gain any more power.

I have seen a few 3/Ses put a 13g on the front and leave the 9b in the rear. This is good for a minor upgrade. But its really only a small upgrade from stock, and really not the best way to go about it.

Supras and RX7s feed one smaller turbo into a larger turbo. That is probably what your co-worker is thinking about. The turbos feed off of the same header and go into the same intake track. Very different plumbing from a 3/S.

later,
Curt