Supra Forums banner

1 - 7 of 7 Posts

·
Registered
Joined
·
257 Posts
Discussion Starter #1
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.:(
 

·
boost is good
Joined
·
772 Posts
with my t78, in first when you get boost tires are just pounded, i spin all through 2nd gear. i would guess unless you have slicks, and/or are a very good driver then for stop light and track races you are gonna want a smaller turbo. also a t78 would suck on the road course. unless there was long strait aways then it would be hard to boost much without spinning sideways
 

·
NFA Pimp
Joined
·
2,735 Posts
How about racing from a roll?? I mean shouldnt you just be able to drop it down to the correct gear and be able to punch it and not have any lag at all with a bigger turbo like the T78 and the T88? How about a auto with bigger stall? Shouldnt I be able to mash on the gas let the car downshitf and then stall up, wouldnt that put alot of load on the motor and spool up the turbos alot sooner then that on a singled car with no converter. I know that on the autos you can spool the turbos up at the line.
 

·
Registered
Joined
·
286 Posts
Lag is there no matter how you step on it...... With a smaller single, the boost would come on quicker and hit max boost quicker.....For example. With a big turbo like a T78....you start spooling around 4000 rpm...but you dont hit max boost (lets say 22 psi) until 5500 rpms. With a smaller street turbo, it comes online earlier (3500 rpms) and hits high boost faster (4500 rpm) and will stay there until you hit rev limiter....obviously this is just a tiny example of what a small single and big single react like.
SH
 
A

·
Guest
Joined
·
0 Posts
HoustonSC300: That's not right. I start making boost at 3500RPM and hit full boost by 4500RPM with my T78.
 

·
Registered
Joined
·
2,913 Posts
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.:(
 

·
Registered
Joined
·
342 Posts
I am surprise how responsive the T-78 is on my 6-speed. I get good power on low end too. Comparng to the stock turbos in twin mode, I think this has more power even below 4k rpm. I think is one of the best all around single kits.
 
1 - 7 of 7 Posts
Top