I know two small turbos will spool faster than one large one, but in reality what would the actual difference be? Twins take more plumbing in the front, but it seems easier for exhaust purposes to design. I like the flipped shorty idea because it allows you to mount where you need or want to, not where some of these ebay headers make you put it.
So mainly if each of you were to do your own kit, would you do single or twins and why? I am open for either but I want to get it right the first time. I want GOOD power with stock stuff but even better with addition of heads and supporting components.
Pope- do you think a T-70 is optimum for what I want? or will it have a lot of lag and not make power until high rpms?
I am by no means the most informed individual on this topic, I will help where I can.
I went with a single on my first kit, and I am going with a single now on my second as well.
single vs. dual: (my reasons)
1. single the exhaust comes together, spins the turbo, and usually exits out of the right side (passenger) of the engine bay where it it is generally open. Whereas with twins one exhaust pipe usually snakes between the engine and the master cylinder, and I did not want to deal with it, and of-course there is the added complications of the compressor side as well.
2. spool time. I have heard no reasonable explanation why two properly sized turbos should spool any faster than one properly sized turbo. rotational mass of one vs. rotational mass of two, combined exhaust flow vs. divided, etc... I am lead to believe that differences in spool time are the result of proper vs. improper sizing and piping design.
3. One oil supply and oil drain vs. two.
4. One turbo to fail vs. two.
5. Cost of one new turbo vs. two new turbos (moot point if using JY turbos)
A Master Power T70 w/ .68 a/r p trim turbine is said to be good for spool from ~2,800 - 5,700 rpm. and .81 a/r and .96 a/r turbine housings open up the option of higher rpm usage or larger displacement engines. I can not speak directly to the accuracy of this information, as my T70 is going on the kit I am building this winter, but it is based on these figures that I went with the MP T70. Also, from my understanding, the MP T70 compressor would generate a compressor map that is more a cross between a T72 and T70 than a true T70, but that is merely rumor that I can not confirm seeing as finding MP compressor maps is impossible. A T70 might be slightly large, but w/ a .68 a/r p trim lag should not be an issue.