11/18/2023 0 Comments B8 holding boost at psi stockThe target air/fuel ratio at WOT on pump gas was 11.5:1, with a 0.46 BSFC (brake-specific fuel consumption) number. Along with our 300hp, 250ci stipulations, for the purposes of the exercise, Garrett engineer Rob Symonds assumed a 3,000-rpm midrange torque peak, a 5,200-rpm power peak, no intercooler, pump gas, and Torrance, California (near sea level) ambient conditions. For the Chevy six, we asked Garrett to do a full engineering analysis, just as if it were specing a turbo for a factory job. But it also has an aftermarket division, Turbo By Garrett, that sells through performance-oriented distributors. I've done over a dozen launches at the track back to back to back within minutes of each other with no issues, and I'm pushing north of 300 ft lbs of torque at the wheels.Industry giant Garrett supplies massive quantities of turbos for OE factory applications. Just don't do it at every stoplight every day and you'll be fine. Unless you have preexisting transmission problems, a few torques and launches won't kill anything. I wouldn't worry so much about hurting your transmission. Then when the green light hits I jump off the brake as fast as I can and basically just hold on for dear life. With the tree lights I have 1.5 seconds after the first light comes on to when the green light comes on and I'm good to go, so I've found that that's the perfect amount of time for my revs to climb enough to spool up my turbo but not go too far and cause my car to bog down. Then when the first lights come on I gun it. Then I do a small preliminary rev and hold it at about 1.2-1.5k. What I've found works best at the track after I'm staged is I jam down the brakes, pumping them a bit along the way to get them as far down as I can. On the other hand if you don't do it long enough, you won't be spooling up your turbo at all and you won't be doing anything. If you're doing it too long I believe there is some kind of electronic/software protection mechanism in our cars because they seem to automatically cut out if the torque converter heats up too much and it'll drop your RPMs big time, again killing your launch. A few times I've either gotten it too high or didn't have my brakes pressed hard enough so I started to inch forward and that killed my launch. I believe I get it up to around 2500 - 3k or so but I'm honestly not sure as I don't take videos of my tach and I'm too busy paying attention to the road/lights/tree and am just going off of feel/instinct. I would like to get some nice launches though :-)Basically you have to get the RPMs high enough to get to where you'll start making boost. I can see a difference in the launch.Ĭan you try to explain the most difficult part, and how to get the car to launch well without bogging? Maybe I am not getting the rpm high enough, as I don't really enjoy the feeling of loading up the drivetrain but holding it all back with the brakes. Perhaps this weekend I will hookup the Vagcom (and research how to log boost) to see what kind of readings I get. My car has 87000km, I thought she was healthy. I don't like brake torquing, feels so bad for the drivetrain. It feels just as quick starting from idle (without brake torque). Maybe by a few tenths, but I can feel the car kind of bog down when I release the brake. I tried brake torquing several times to 2.5-3k rpm in S mode, then gunning it, and that was NOT improving my 0-60 times. I am definitely reading consistent 18-18.5psi boost with the Torque app, and a generic OBD bluetooth reader from eBay. It's only a 50hp difference, which they probably achieve with boost increase and timing advance.ĭon't S4s go from 11psi stock to 16psi stage 1/2? That yields them much more hp. If 22psi on stage 2 is accurate, I think 18psi stock is reasonable. My stage 2 is around 22psi.Īmazed at the differences we are seeing in this thread. I could swear stock boost is around 11psi.
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