GT6152 Boost

[bad V6]

I'm trying to get together a what kind of a tune I should be working towards when the track reopens come Spring. What kind of boost does the GT6152 seem to produce the best results?

I haven't had a chance to dial the car in this past year, and only made it to the track a couple of times. The car seems to be running good the way it is set up for on the street: 110 octane, 22# boost and FP@43#. The best time thus far is a 1.929 60', 8.001@87.43 1/8, 12.49@110.06 1/4, leaving @ 3# on BFG drag radials @ 18#. Tried leaving @ 5# and the tires went up in smoke. Come Spring there will be a set of M/T radials out back. There should be a lot left in the car, I just need some help extracting it. Any advice would be greatly appreciated.

Thanks,
Pat

 

[RUQWKNF]

The 6152 turbo, with the E cover typically likes to be run in the 18-26psi range. With your combo, race gas and race chip I would crank the boost up to around 24-25. This should net you a minimum of 2-3 mph through the traps. You definitely need to work on your short times. If you were able to improve your 60fts to the 1.60 range, this theoretically should put your ET in the high 11s. With the E cover 3" inlet 2" discharge, then I wouldn't push the turbo past 26psi (unless you were running alky, due to the excess heat created at this level), but if you have the S cover, you could push it to 28psi. I have attached the comp map of the 61mm comp wheel, this is from Garretts website. FYI 2.5-3.0 PR (or Pressure Ratio) is close to 24-30psi. Corrected Air Flow is in lbs per min, if you take the lbs per min and multiply X 10 you get flywheel hp. So at around 2.5 pr, this wheel is at around 70-72% efficient and is flowing 58-60 lbs per min of air flow. (580-610 fwhp) Other things will play an important factor such as cam selection, head work and exhaust setup. Obviously with cam and head work, you will be able to run lower boost levels to make more power. Don (don3d) learned this first hand when he was running this turbo on his GN.
Hope this helps.
Patrick

 

[bad V6]

RUQWKNF, thanks for the insight into what I should be expecting. I agree that I do need to work on my short times, I just haven't had a chance to spend much time at the track. I realize that getting the 60' time down will net a big improvement in the 1/4 ET, and that the car is capable of atleast a high 11 second timeslip. Thus far it has been picking up around .2-.25 in the 1/4 per every .1 gained in the 60', does this seem on target with what I should be picking up? The turbo does have the E-cover. The timing was at 21 in 1 & 2, 19 in 3 & 4. The car seemed to be running fat down low, and really came alive at about 30-40 feet out of the hole, slightly breaking the tires loose. For this reason I am adding a Gen2 to help lean the bottom out a little bit, and the ability to adjust the timing. The engine is currently a 78,000 mile unopened long block with only bolt-ons. I've thought about a set of heads, but decided against it until it is time to do a complete rebuild.

 

[RUQWKNF]

Yep, your 60ft vs ET improvements seem about right. If it's taking longer to spool up, your converter might be too tight. Typically if the Vigi is rated to 3200 stall speed, this would be what it should easily foot brake too, however it might only flash to around 2900-3000. The 6152E with a .63 A/R PTE housing really likes to have a converter that will flash stall to around 3200 (foot brake 3400-3500). I've known a lot of people who have had to have their 9.5 Vigis re-stalled in order to make foot braking a lot easier. Another thing with regards to timing and race gas, I've always had the best luck running 20* timing in all gears when running 100 octane and 26* timing in all gears when running straight C-16.
Here is a link to help understand compressor maps.
TurboByGarrett.com - Turbo Tech103

HTH
Patrick

 

[bad V6]

RUQWKNF, thank you for giving me a better understanding of what I should be looking for and trying to achieve.

I was mistaken about the timing, after pulling up the DS file it showed 19/17. I was having trouble pushing through the beams while trying to build boost at the line, seems the previous owner had backed the off rear brakes. The converter does seem a little tight, probably does flash at 2900-3000. I've only had the opportunity to make two passes in the car since going through the front and rear brakes and installing a line lock. It's amazing what a good set of pads, shoes, and rotors can do for a vehicle. Now I can foot brake the car with ease, but was limited to how hard I could leave due to poor track prep (street cars running) during T&T session, last day of the season.

I would hate to think about pulling the converter for a restall after just installing it less than 300 miles ago. The car will break the BFG drag radials loose up around 30 MPH. It runs real good out on the street, just a little turbo lag. Is there anything I can do to help compensate for the converter flashing to low, that would help lower my 60' time.

Thanks,
Pat