11.97 on a stock turbo!

murphster

Well-Known Member
This is a full weight 1987 GN with a stock motor, turbo, and IC with a dutt neck on pump gas and alky.

See the thread here: anothr magna stock turbo in the 11's - TurboBuicks.com

It was nice and cool last night at Englishtown. I've been trying to get into the 11s for a long time on a stock turbo on other cars, but never got there. I knew my GN had good parts and was running well though.

This car has been hooking real well even though there is minimal work done to the suspension. The tires are almost new MT DRs, 255/60/15s making them 27" tall. Might be make a good compromise between the 28" tires being too tall and bogging down a stock combo and the 26" tires being easier to spin.

I think one key was the restalled D5 converter, as it seemed matched to the combo perfectly. The tranny is just a basic street/strip build, nothing fancy.

The whole car is really tight as it was a South Carolina car. It has 116k miles, but was probably not beat on much and never saw much boost.
 

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I think that 1.5 60 foot time is great with a stock turbo. Whats your starting line procedure? What boost do you leave at?
 
First, I'm running almost new MT DRs at 22psi. Unless its real cold, no benefit to going less than 20psi in these. The contact patch is good at those pressures and it won't hurt the mph by running real low air pressures.

The brakes were just replaced and adjusted correctly. New springs from Kirbans all around and old shocks.

For the burnout I went around the water and spun them until I can see smoke on the side mirrors. No line loc, and I press the brakes as light as I can during the burnout so hopefully the rear brakes won't heat up too much. I ease out of the burnout and look at the track to make sure I'm in the groove and not off to one side.

Once I light the second beam I mash the brakes hard and just give it enough throttle to come out of vacuum and bring it up to zero boost or so, not enough to start loading the suspension or build boost. As the yellow lights start to come down the tree I give it maybe half throttle or so, maybe less, so that boost will start building. When I get to the boost I want to leave at I go WOT and let off the brake.

IMO, the key thing when on the footbrake is to leave while the boost is on its way up and the suspension is starting to load up. You kind of feel it rock while the suspension is loading. You don't want to bring the boost up to 6 or 7 lbs and sit there for a few seconds. And you don't want to floor it right away or you'll end up rolling out and leaving before you build much boost. You are only giving enough throttle to build boost and then flooring it when you are ready to leave. I just refer to it as catching it on the way up. If you can't build boost at partial throttle like this, you may need a looser converter or you might have an exhaust leak in a header or crossover pipe. The rear brakes need to be in good shape too. I also have an RJC boost controller that probably helps some.

Its not the best for reaction times until you get used to it, but it doesn't matter during test and tune. You can sit there for 2 seconds or red light and it won't affect the time, so I never worry about it when you are trying to feel the car out. Just leave when the car is ready.

Luckily I had a friend show me this a long time ago and it helped a lot. I also used to run lower air pressure in the MT DRs, but after seeing other cars run more pressure my 60fts improved once I went to the low 20s psi.

On the three runs, I left at 6, 8, and 10psi boost, improving the 60ft each time. Better to go in small steps if you are not sure the track will hold depending on the prep, rather than waste a run because you spun like crazy. I'd image I was getting close to the limit on the boost I could leave with without spinning, but I never found out.
 
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