1985 Pontiac Grand Prix, 350 cubic inch Chevrolet, TPI
Posted: Tue Nov 27, 2007 1:14 pm
Name: Andrew
Vehicle: 1985 Pontiac Grand Prix
Engine: 355 CI Small block Chevrolet (Iron heads, Comp Cams XE262H camshaft)
Injection: Tuned Port Injection (TPI) from a 1989 Camaro 5.7L (22lb injectors)
Description: MSI v2.2
Hardest parts of this were reaming and spot-facing the post-1987 lower intake manifold so I could bolt it onto my pre-1987 heads and the fuel system.
My big lesson converting this carb'd car to fuel injection: screw metal fuel lines, go AN braided. Raw materials are more expensive ($6/foot for the hose, $5-$8 for the end fittings at my local speed shop), but it is just so much easier.
Earl's AN fittings are superior to Jeg's and Aeroquip from the standpoint of assembly.
I ran -6 AN supply from an external Walbro pump to the TPI, and attempted to use the factory vapor line as a return. It was rusty and burst the first time I fire the fuel pump. I then just ran -6 AN back to the rear axle and then rubber from there to the tank.
There is also a restrictor in the return inlet to the tank that must be drilled out (pull the sender assembly and cut off the little baffle around the vapor return, you'll see the brass restrictor), and you'll have to vent the tank somehow (I drilled a very small (3/32") hole in the gas cap) or it'll pressurize and eventually burst, which would be bad.
I guess the environmentally friendly way would be to run a new vapor return from a nipple welded/screwed into the filler neck up to the charcoal canister and then on to the intake manifold, but I needed to get this thing back on the road.
Use the throttle cable and TV cable for a 305 TPI Camaro/Firebird.
I was able to use a vacuum advance HEI, but there's no timed port vacuum source on the TPI throttlebody, so be conservative with your static timing.
The Megasquirt itself fits in the spot vacated by the factory ECM. Once I'm done tuning, I'll be able to tuck it away and nobody will know it's there.
It started and idled using the default VE table and constants from Bruce's 350 TPI, but this larger camshaft requires a lot more fuel to actually move the car. After a ten minute drive and one run through MegaLogViewer's VE analyzer, I was able to drive car to work (12 miles mixed freeway and City), though it would buck at high loads and ran rather rich at Cruising RPMs. Another analyzer run on the datalog from this morning's drive has built a much better looking map. We shall see if it is actually better.
I will come back and attach my MSQ file once I'm happy with it all.
Vehicle: 1985 Pontiac Grand Prix
Engine: 355 CI Small block Chevrolet (Iron heads, Comp Cams XE262H camshaft)
Injection: Tuned Port Injection (TPI) from a 1989 Camaro 5.7L (22lb injectors)
Description: MSI v2.2
Hardest parts of this were reaming and spot-facing the post-1987 lower intake manifold so I could bolt it onto my pre-1987 heads and the fuel system.
My big lesson converting this carb'd car to fuel injection: screw metal fuel lines, go AN braided. Raw materials are more expensive ($6/foot for the hose, $5-$8 for the end fittings at my local speed shop), but it is just so much easier.
Earl's AN fittings are superior to Jeg's and Aeroquip from the standpoint of assembly.
I ran -6 AN supply from an external Walbro pump to the TPI, and attempted to use the factory vapor line as a return. It was rusty and burst the first time I fire the fuel pump. I then just ran -6 AN back to the rear axle and then rubber from there to the tank.
There is also a restrictor in the return inlet to the tank that must be drilled out (pull the sender assembly and cut off the little baffle around the vapor return, you'll see the brass restrictor), and you'll have to vent the tank somehow (I drilled a very small (3/32") hole in the gas cap) or it'll pressurize and eventually burst, which would be bad.
I guess the environmentally friendly way would be to run a new vapor return from a nipple welded/screwed into the filler neck up to the charcoal canister and then on to the intake manifold, but I needed to get this thing back on the road.
Use the throttle cable and TV cable for a 305 TPI Camaro/Firebird.
I was able to use a vacuum advance HEI, but there's no timed port vacuum source on the TPI throttlebody, so be conservative with your static timing.
The Megasquirt itself fits in the spot vacated by the factory ECM. Once I'm done tuning, I'll be able to tuck it away and nobody will know it's there.
It started and idled using the default VE table and constants from Bruce's 350 TPI, but this larger camshaft requires a lot more fuel to actually move the car. After a ten minute drive and one run through MegaLogViewer's VE analyzer, I was able to drive car to work (12 miles mixed freeway and City), though it would buck at high loads and ran rather rich at Cruising RPMs. Another analyzer run on the datalog from this morning's drive has built a much better looking map. We shall see if it is actually better.
I will come back and attach my MSQ file once I'm happy with it all.