Twin turbo setup... different psi from turbos possible?

[peachpuff]

What would happen in a twin turbo setup if the large turbo is pushing 30psi and the small one 15psi. Would the airflow from the large turbo basically go back through the y-pipe that connects the two and choke the small turbo due to there being less pressure coming from the small turbo?

A friend is about to attempt to run a gt35r up front and a 16g mounted in the back but the varying pressure he plans to run from both turbos didn't sound right to me.

 

[tsi1991awd]

I don't know a whole lot about the bi-turbo setup...there was someone on here doing a bi-turbo setup and if I remember correctly, the idea was to use the smaller turbo to spool the bigger turbo faster or something....not a large turbo up front and small one in the back. That doesn't make much sense.

 

[asrdave]

the turbo setup i think you are referring to is 99gst_racer's he is running a compund setup with a 16g then to a 60-1 i think, if you search for it it'll come up, very nice project he did

 

[XiKeiyaZI]

Compound Turbo Setup

Basically you use the smaller turbo to spool the larger turbo faster.

Just look in the Fabrication Section. 99gst_racer has covered pretty much every inch of this/

 

[LiquidX]

I believe twin turbo would be one turbo blowing air into x cylinders and the other turbo blowing air into y cylinders. You would mainly see twin turbo setups on 6 cylinder and up as one turbo would only blow into half the motor and the other into the other half.

 

[abaum565]

I believe twin turbo would be one turbo blowing air into x cylinders and the other turbo blowing air into y cylinders. You would mainly see twin turbo setups on 6 cylinder and up as one turbo would only blow into half the motor and the other into the other half.

On a twin turbo setup it will more than likely be exhaust gases "from" x cylinder blowing "into" turbo 1, and exhaust gases "from" y cylinders blowing "into" turbo 2. From there the turbos are generally joined at the intercooler or some sort of y pipe and they both go into one intake manifold. You wouldn't see each turbo separated on the exhaust and intake on a 6 - 8 cylinder application.

There are a few types of multiple turbo setups; compound, sequential, twin. It would be nice to know what you plan on running and selecting turbos from there.

 

[ramsack]

the 1990's 300zx are the only car i know of that divides each turbo completely by banks of cylinders. other cars that are twin turbo 6-cylinder tend to join them on the intake side and they usually end up not running the same psi and one has to work way harder than the other, and one usually dies a lot faster than the other.

 

[DSMDriver69]

the 1990's 300zx are the only car i know of that divides each turbo completely by banks of cylinders. other cars that are twin turbo 6-cylinder tend to join them on the intake side and they usually end up not running the same psi and one has to work way harder than the other, and one usually dies a lot faster than the other.

Isn't the mk4 supra the same way as the 300zx? And I think the fd rx7 is the same, but I could be wrong.

 

[ramsack]

the fd rx7 is sequential, and has 1tb, and the mkiv supra is sequential, so 1tb, so no. the 300zx has 2 throttle bodies, 2 intake manifolds, etc.

 

[noavgjoe]

Have your friend take a look at this build. It may help even though the turbo's are in the reverse order. http://www.dsmtuners.com/forums/custom-fabrication/336541-my-compound-turbo-set-up.html

 

[black_gst]

I know the rx7 is a rotary smart ass, which yes means there is no pistions.

My point was since its a rotary it has only one TB like the mk4 where we were talking about the 300zx that has two TB's and keeps each turbo seprate completly and since you know the FD is a rotary you would know it wouldent be possible for it to be like the 300zx... but of course you already knew that

 

[XiKeiyaZI]

;P Chill... otherwise the great and powerful mods will come to smite you.

The best way that I've seen to do this is in the link above.

 

[black_gst]

it wouldent be the 1st time... anyway if they dont like that smiley they shouldent have it

 

[dsmdeliveryboy]

YouTube - 99GSTracer's Channel

 

[viperlp01]

Pauls (99gst_racer) uses different atmospheric pressures to make the boost he makes. The LARGER one feeds the SMALLER one. The larger one raises the atmospheric pressure that the 16g sees and then the 16g multiplies it so the 16g doesn't have to work that hard to make 40psi. He has a great explanation on how compounds work in his thread and unless you went with a compound any other twin turbo set up is just stupid on our cars.

 

[rlacasse1]

I am going to have to agree with Viper on this. The Compound setup like Pauls is the only sensible thing that should be done.

 

[peachpuff]

Pauls (99gst_racer) uses different atmospheric pressures to make the boost he makes. The LARGER one feeds the SMALLER one.

My friends isn't a compound setup though, its simply a twin turbo one with different sized turbo's, problem is(imo at least) one is running at half the pressure... what will happen in that y-pipe that connects the two since you have different pressures coming from the turbo's. Normally twin turbo setups run the same pressure on both turbo's so there's no issues.

 

[Zdrummer15]

Is this even on a DSM? I don't see there being too many ways other then the mentioned compound set-up to benefit or even run 2 turbos at all on a DSM.

 

[delta448]

It seems as if your friend is ignorant about how a turbo works.

He will get little to no spool from either turbo unless they are compounded or sequential and the exhaust is also thoughtfully wastegated. If they are set up in parallel, the 16G won't come online until the 35r's turbine creates enough backpressure to route exhaust flow through the smaller more restrictive TD05H turbine. The 35r also won't reach a good compressor rpm speed due to the exhaust leak which is created by simulataneously feeding exhaust energy to the 16G's turbine. I'd expect to see spool up at 5500+ and less than 2 bar maximum compressor output pressure.

 

[Choch1]

Tell your friend to go for it, then sit back and enjoy the show. Clearly he knows little to nothing about what he is doing....

 

[AK Maniak]

Tell your friend to go for it, then sit back and enjoy the show. Clearly he knows little to nothing about what he is doing....

unless your a total dick don't do that.

Point him towards this thread so he can read the opinions of multiple people that are very well educated about this stuff.

 

[peachpuff]

Is this even on a DSM?

No its not a dsm, there's simply not enough turbo knowledge on the forum's we frequent on so i figured i'd ask here since i had a dsm before and ya'll know turbos very well.

It seems as if your friend is ignorant about how a turbo works.

He will get little to no spool from either turbo unless they are compounded or sequential and the exhaust is also thoughtfully wastegated. If they are set up in parallel, the 16G won't come online until the 35r's turbine creates enough backpressure to route exhaust flow through the smaller more restrictive TD05H turbine. The 35r also won't reach a good compressor rpm speed due to the exhaust leak which is created by simulataneously feeding exhaust energy to the 16G's turbine. I'd expect to see spool up at 5500+ and less than 2 bar maximum compressor output pressure.

The turbine sections are in a way compounded just not the compressor side, the exhaust outlet from the gt35r goes all the way to the back of the car and connects to the 16g's turbine inlet. But the compressor sides are connected with a y-pipe before the intercooler... and this is where my concern is. 30psi from one turbo meets 15psi from the smaller turbo in the y-pipe, what will happen here? Will the air from the smaller turbo basically hit a wall and choke since theres twice as much pressure in the y-pipe its connected to?
Maybe he should compound them, but with the distance from the front turbo to the back turbo the exhaust gases would loose all their heat and make the whole thing kinda moot. There's no room to put two turbo's up front so the rear mounted one is the only solution it seems.

 

[ramsack]

nope, they have 2 y-pipe that joins the inlets and outlets. they do have 2 intercoolers, though. i suppose the turbos fighting each other wouldn't be a huge diffference between the 2, since the wastegates will open at the same boost. this would only spin them equally if the exhaust flow is perfectly the same between banks and other things flowed the same.

if i was building a 3000gt i would personally go single turbo, and run 2 fuel pumps, 2 fuel lines, 2 afpr's, etc. if i was going to keep it twin turbo i would still go with doing that fuel stuff. they have the crappiest fuel system and i think it's why they tend to blow so easily, even stock.

 

[Nati0nalxCrisis]

if i was building a 3000gt i would personally go single turbo, and run 2 fuel pumps, 2 fuel lines, 2 afpr's, etc. if i was going to keep it twin turbo i would still go with doing that fuel stuff. they have the crappiest fuel system and i think it's why they tend to blow so easily, even stock.

Personally as much as I like the look of a 3000gt Vr4, there just seems to be no room at all to work on anything in there. That motor is just CRAMMED in there. 4g63's on the other hand, such a breeze.

I agree on that being part of the reason of them blowing as well.

 

[tallywacker]

YouTube - 99GSTracer's Channel

The comments on his channel are hilarious.