Question for 3uz-fe

[LS430 Driver]

I saw the thread about the twin turbo'd SC430, and i know that the 2005 LS430 and the SC430 share the same motor and tranny or so i've been told. Now twin turboing would in theroy be possible correct? now whould it be smarter to run a twin turbo set up or a single turbo set up. I'm thinking a single would create more lag and spool at high rpm's but would be a dyno queen. A twin turbo setup would allow lower rpm spooling but less power, am i right?

and what would you do

 

[Lextreme II]

Single and Twin has not to do with spooling. Its has to do with sizing...... I dont think your car will run very well with twin T88. However, with a GT35R, your car will run very well. Please dont get confuse with twin and single. Think of it as proper combination.

 

[LS430 Driver]

Single and Twin has not to do with spooling. Its has to do with sizing...... I dont think your car will run very well with twin T88. However, with a GT35R, your car will run very well. Please dont get confuse with twin and single. Think of it as proper combination.

i was just wondering, because if you take an MKIV for example. People convert the twin turbo 2JZ to a single correct? Well then dont they do that for the power gains? And wouldn't having a bigger single turbo rather than smaller twin turbo's create alot more lag than twin turbo?

 

[Lextreme II]

i was just wondering, because if you take an MKIV for example. People convert the twin turbo 2JZ to a single correct? Well then dont they do that for the power gains? And wouldn't having a bigger single turbo rather than smaller twin turbo's create alot more lag than twin turbo?

Anything big will create lag regardless of number of turbos. Same apply to any engine. If a Supra owner put in Twin T88, the car might not run too well. However, if he put twin HKS 2835 or similar it will run great. I think people get stuck with the concept of single vs. twin.

 

[chrisman]

sizing is very important in chosing turbos.. but, figuring out what would make you happiest is a tough thing to figure out. a large single turbo can make big numbers, but so can twins..it all depends on having a realistic expectation on what you truly would like better..making big numbers on a dyno, or having a car with a useful-streetable- power band..
on the mk IV supra, toyota tried to have the best of both worlds by making a kind of "sequential" twin turbo system.. one would come on before the other.. i think anyway,, i have never worked on a mk IV, but i think we had a thread all about it on lextreme somewhere.. a properly sized sequential turbo system would probably be the best for a streetable aplication..--imo..

 

[TOBES]

Sizing the turbo('s) to the airflow requirements of the engine to produce the boost levels required in the rev range required is the most important factor. Similar to choosing a cam in principal. Get it right and the car will be a pleasure to live with on the street and a hell of a lot of fun....

In the power stakes there is no difference between single or twin. There are simply too many variables to make an accurate comparison. Exhaust manifolds, turbo position, intake piping, intercooling, wastegate and blow off valve sizing, control and positioning, throttle bodies, etc are different making any comparison apples and oranges.
Produce the boost and reap the power...

Spool times are a different story...
There is a law of physics called 'The radius of gyration', I think, that states that an object twice the size of another requires four times the force to accelerate rotationally. In other words the big single will spool slower than twins as, although it has twice the exhaust flow, it would require four times the flow to spool at the same rate...
Makes no difference to the ultimate power level achieved but a significant difference to your throttle response...

 

[Lextreme II]

for the 4.30 liter i would pick single GT35R for daily application. Single would be much easier to manage. One turbo, one wastegate, one oil inlet and outlet line and so on. The less it is.. the less potential problem you have....

 

[TOBES]

Dunno Lex... Pretty much 6 of one and a half dozen of the other...

With twins the intake piping is more complicated but you trade that off against simpler exhaust manifolding...
Intercooling is similar using the twin bottom entry/single top outlet you have designed...
On the street use internal wastegates as you would never notice the difference...
Oil lines are only two Tee fittings and some hose...
Overall the difference is negligible...

I read an interesting article in 'Zoom' on this subject, written by Martin Donnan, and he concluded that twins were the best on a street motor as he rated throtle response and driveability above everything else...

Power wise he also noted that the current 'HP Hero's' dyno queen uses twins to produce well over 1100kw from a stroked 5.0L Holden motor...