With a well-chosen single capable of 650-700 RWHP, the boost threshold is plenty low, IMO. I don't even notice my T-64 making boost later than the sequential twins, even though the T-64 is a few hundred RPM later to make, say, 6 PSI. However, by the time the stock twins will make 10 PSI, the T-64 has caught up with them and in fact is smoking them both in terms of boost pressure at a given RPM and power production. (I made a matrix of boost pressures at given RPMs in various gears on the stock twins and the T-64 on stock cams. I need to complete the matrix with the T-64 on the 264 cams and send it to Andi or someone so they can put it up on their site.)
Andi posted a dyno chart with the twins in sequential mode overlaid on a T-64 chart. The spool was identical until the T-64 blew the twins away at higher power levels. Maybe someone recalls the link to that chart. I'm sure you can find it on Andi's site,
www.boostaholic.com, I think.
I'll assure you (particularly if you have a 6-speed) that if you go with a turbo with a compressor inducer in the 63-64 mm range and a .70 exhaust housing, and the car is decently tuned, you'll never have a second thought about lag.
This may even be true with larger turbos, but that begins to depend more upon the individual as some people feel that the larger turbos are a bit laggy while others feel that it isn't an issue at all.
Steve
les said:
I hear a lot of people talking about the amount of lag with a big single that can blow 650-800rwhp. My question is for street and road racing is the lag unbearable is it streetable. Is it easy to overwhelm the supra's traction at low rpm (1500-3500) or does this only occur at 4500rpm or more . I'm trying to get an impression on whether its worthwhile to upgrade to over 500rwhp. Basically is the power usable only at high rev's. Will I lose street starts.
