twin and single turbo

[jdmhagen]

what is the difference between twin and single turbo on the 2jz motors(besides the number of turbos) because i've heard of ppl converting their twin to single...can u get more power out of a single turbo? what are the pros and cons between the two?

[TcmaBoy]

The reason that people run a big single is simple. Singles are cheaper, you are only buying one turbo instead of two. They are also simpler to set up. One turbo, one inlet, one exhaust, one waste gate, etc. In terms of peak power there is no difference. The idea behind running twins is a slightly faster spool time. Two smaller turbos have less mass to get moving so they are supposed to be slightly more responsive. The thing is that you only have half the cyl driving the turbo, so the quicker response is diminished. If you are going for big power then there is really no advantage to running twins.

The only advantage twins give is with a sequential set up. With sequential turbos you have a small turbo and a big turbo. At low RPM all the exhaust is driving the small turbo, as RPM rises and you exceed the small turbo a valve diverts exhaust to the bigger turbo. The big turbo takes over for the small turbo. This gives the low end response of a small turbo and the big power potential of a big turbo. The problem is that a sequential setup is more complicated and more expensive. The stock set up on the 2JZGTE is a sequential set up. This is what makes it nice and responsive.

Be aware that going for big power means a big turbo. Big turbos are not responsive. They have a high boost threshold, which means that you will not see boost until over 3K RPM. In terms of drivability this means the car will be a slug on the street. Big power is more for race cars and dyno queens. If you drive the car on a regular basis I would stay down in the 400 HP range for drivability and reliability reasons.

[jdmhagen]

thanks tcma boy, that clears it up perfectly