Thread: 94 GP with 3100, builing motor, want mods

Originally Posted by 94b4u

I have a 94 grand prix B4U package but not GTP. It has the 3100 in it. My motor is using (leaking oil). I have another motor I was going to build and see what HP gains we could get. Does anyone have any proven upgrades or any links with some good information. It is an OBD1 system so sensors are les crutial then an obd2. I have heard about using a 3400 intake and a larger TB. What are the gains?

A 3400, or a '00 & up 3100 flow about the same. You're looking at about 175hp with the complete top end swap. It's only a 10 - 20 hp gain. Honestly, the only way to make any of the pushrod GM motors fast is to boost them. For example, the McLaren Turbo Grand Prix uses the same LHO 3.1 many GMs came with (starting with the AWD version of the '88 6000 STE), but instead of only putting out 140 horses, the Garrett T-25 turbo boosted it to 205 hp/225 lb ft, and that's with a very tiny turbo meant for 4 cylinder cars, and piss poor tuned chip by McLaren (they were only given 2 weeks to come up with the tables). A reprogrammed chip alone boosts the performance of those quite a bit more (in many cases, stock L67-like performance, or faster).

But short of forced induction, all you're going to find by dumping money into rods, cranks, etc is a much lighter wallet, without a much more powerful motor to show for it. And with the forced induction, you're going to have to fabricate a set-up yourself. There's really no aftermarket for these motors. Other than that, you may want to shoot for a 3500 top end swap. More significant gains than just a 3400/newer 3100 swap, but also a lot more involved. This swap is popular with a lot of the Beretta guys right now.

Yes, it will be a lot of work, as you'll have to pretty much fabricate everything from scratch. Though if you head over to 60degreeV6.com, you'll find several have done this, so at least you'll have some kind of a blueprint for what you're going to need, and possibly specs on the bends in piping and so forth.