Twin turbo manifolds??

[OneJoeZee]

In fact, you yourself stated:



Your opinion as stated above clearly implies that there exists “good reasons” under some circumstances to use a twin turbo set-up. If twins were “retarded” or “a waste of money” how could there be “some good reason to do so”?.

You speak as if I have contradicted myself or something. I never said twins were retarded or a waste of money. Feel free to show me where I said that in this thread. Why would I say that? I have a Blitz TT setup in my own Supra. Don't confuse my posts with other's.

This statement is just flat wrong . The reason is:

Because although one turbocharger is more efficient than two turbochargers, a smaller turbo takes less energy to spool than a larger one of same design.. (Stay with me here for a second and I’ll get to the point.). And yes, one turbo per cylinder bank is optimum (with regard to the tendency for two turbos to cause scavenging of exhaust gasses between the two exhaust valves that would be simultaneously open, thereby causing them to have both uneven enthalpy and virtually unpredictable pulse pressures at the turbochrger’s inlet.

This uneven pressure in constant variation (pulses) would affect both of the turbochargers speed and make it near impossible to get even levels of boost out of them (again, we’re talking about one bank of cylinders).

But this is only applicable when two turbochargers are run in parallel.

The car I used as an example (300ZX) is a sequential twin turbo, as are most twin turbos used on an inline engine. You neglected to address the physics of one turbo vs. two turbos in any context other than parallel. The smaller turbos used on sequential forced intake systems are smaller and therefore more efficient when viewed individually.

This is significant because:

Since they are spooled up individually with the second turbo effectively off-line until the first is spooled up and boosting, and then using that pressure to spool up the second turbo, you have more than made up for any efficiency deficit that would cause the two turbos to “lag” more than a big single turbo.

If fact the whole reason for two turbos on a single bank of cylinders when used sequentially, is to attain greater boost levels at significantly lower rpm. And this it does quite effectively, resulting in an engine that has boost (i.e. power) at much lower rpm’s (the assertion that a single turbo would have a wider useable power band is absurd), with the trade-off being a small loss of top-end boost (this is where the efficiency of a single is an advantage).

My statement about the nature of twins is not wrong. Read the posts I referenced again and look at the graph of the twin 28RS turbos versus the single 40R turbo. The 28RSs spool later but have a more linear curve. The 40R spools earlier and the curve is not as linear. The 40R has a wider powerband. Again, my own setup behaves in a similar manner with twins. Full boost comes on later but the power delivery is very linear compared to single turbos that tend to hit much harder.

Why are you mentioning sequential turbos and I6 engines in the same sentence as the 300ZX as if the car had either? The 300ZX is powered by a V6 with parallel twins. So there goes that out the door for you.

No one is even talking about sequential setups anyway. We are talking about Supras and aftermarket twin turbo kits because that is what is available. Do you know of any sequential turbo kits for the 1JZ?

 

[OneJoeZee]

http://www.supraforums.com/forum/showthread.php?t=265570&highlight=suprawood

 

[suprabad]

You speak as if I have contradicted myself or something. I never said twins were retarded or a waste of money. Feel free to show me where I said that in this thread. Why would I say that? I have a Blitz TT setup in my own Supra. Don't confuse my posts with other's.





My statement about the nature of twins is not wrong. Read the posts I referenced again and look at the graph of the twin 28RS turbos versus the single 40R turbo. The 28RSs spool later but have a more linear curve. The 40R spools earlier and the curve is not as linear. The 40R has a wider powerband. Again, my own setup behaves in a similar manner with twins. Full boost comes on later but the power delivery is very linear compared to single turbos that tend to hit much harder.

Why are you mentioning sequential turbos and I6 engines in the same sentence as the 300ZX as if the car had either? The 300ZX is powered by a V6 with parallel twins. So there goes that out the door for you.

No one is even talking about sequential setups anyway. We are talking about Supras and aftermarket twin turbo kits because that is what is available. Do you know of any sequential turbo kits for the 1JZ?

I never quoted you as saying twin turbos are retarded. I only quoted it as being said in this thread.

Also, I did not say you contridicted yourself, I said that you only addressed the physics of efficiency as it relates to twin turbocharges in parallel. Sequential is clearly the arrangement of choice for OEM's, and therefore relevent.

I mentioned the 300ZX because while it is a V6, and does not have sequential turbochargers, it does have two turbos, and since they are on seperate cylinder banks it fairly mimics some of the properties of a sequentrial, in both quantity and delivery of power. Maybe it wasn't the greatest example apples for apples, but it still illustrates the point I originally was making which is that twins are not retarded or useless. And yes, I misspoke when I said the 300ZX was sequential. My apologies.

And while full boost may come on later for twins (there are some variables in this area also), I think you would agree that two smaller turbos (sequential or not) start boosting at a lower rpm, which is why I asssert that this set-up creates more "useable" power than one huge turbo. So, in fact it doesn't "go out the door for me ".

I hope I've addressed all your concerns. I tried not to do it in a manner that you would interpret as a personal attack. FWIW.

 

[OneJoeZee]

Well, I don't want to make anymore general statements. There's alot of factors and variables to consider that I don't want to continue elaborating on. Apples to apples comparisons aren't easy. It's late and I'm going to sleep.

 

[suprabad]

Well, I don't want to make anymore general statements. There's alot of factors and variables to consider that I don't want to continue elaborating on. Apples to apples comparisons aren't easy. It's late and I'm going to sleep.

Agreed, me either.

ditto on the sleep

 

[Rich]

Not addressed to anybody specific, but try thinking in air mass flow in stead of boost. Boost does not tell all when making power or spooling up.

Then when thinking in air mass flow compare one big turbo and two smaller ones which together make the same power as the big single. Then take into consideration all you know about thermodynamics, physics and VE of turbo's and draw your own conclusion.

Don't compare real life set-ups because that is always apples to pears, there's too many factors that play a role to make a sensitive comparisment.

 

[tlo86]

i want 6 turbos

 

[suprabad]

Don't compare real life set-ups because that is always apples to pears, there's too many factors that play a role to make a sensitive comparisment.

I guess you're right about that. To debate theory, it makes sense that reffering to different set-ups would make for an uneven playing field. Never really thought about it that way.

But you got to admit, it's hard not to think in terms of practical application, at least for me, as I tend to be a pragmatist.

Good point though.:icon_bigg

 

[RacerXJ220]

Twins aren't really worth it unless you have some good reason to do so.

Yo momma.

 

[meet07]

so what about building the valve train to wistand maybe 8 grand. I just looked at this magazine yesterday that had a 2jz reving t 7900rpms with twin t3/t4's making a hair over 1000whp. If the twins spool up later would it not hit harder with 2 large turbo's than one large turbo??

 

[RacerXJ220]

Stock 1J valve train will support 8K already for the most part. I'm not saying you can blindly run high lift cams or anything.

Power wise, the stock cams will hold you back high rpm.

I'm sure the 2J you're talking about, has had more money dumped into the head than most good condition MKIII's sell for. Ferrea everything, OS valves, full port/polish + labor, with some HKS 280 cams or custom grinds. That head can probably spin to 10,000rpms and ingest birds.

Depending on the size of the twins yeah. Take the flow chart of a smaller turbo where it peaks, add it up, then compare it to a single turbo's flow chart is and you'll have an idea of the lag by looking at that larger single turbo's dyno's. I read on SF about SP's new 2J Sequential Twin kit, two 58mm's are similar to a single 78.xmm. Of course, taking into account which .AR, CHRA's, and shizz is confusing so yeah.... If you want to go twins, just buy a kit, they're twice as fun to install/uninstall and dyno time costs the same regardless!!!

 

[meet07]

Yes these guys did spend a bunch of money on the head as well as a rebuilt bottom end but at 10psi they where making 500whp. I just recently read about them and there setup in some mag that I have in the car(to lazy to go see what it is right now)Thats got to tell ya something. I was just curious of who made a twin manifold. Im probably going single turbo anyways. But thanx for all the debating. I got a lil education.

http://www.youtube.com/watch?v=PO5vt3QMX1w
http://www.youtube.com/watch?v=_MsqA-C3vGI
http://www.youtube.com/watch?v=13gGQC5fha8
http://www.youtube.com/watch?v=VGup8ABckrw


Thanx to all

 

[RacerXJ220]

http://www.supraforums.com/forum/showthread.php?t=455869&page=8

Twin kits are still in R&D. It makes me happy.

This kit, is sex.

And true sequential.

 

[meet07]

why is the wastegate in the DP??

 

[Freshmaker]

why is the wastegate in the DP??

They use 4 valves in the entire system. That one is part of the sequential system :icon_evil

 

[RacerXJ220]

It's a sequential twin kit, one comes on first, then the other one.

 

[bloodasp90]

well i know theres a few people out there that have told me not to go twin, but i am going twins myself, just waiting on a few more things to come in before i start my own twin build thread