How hard to put 3.1 pushrod engine in DOHC GP?

[TazMan]

If I came across a 90's DOHC Grand Prix with a bad motor, what would be involved in swapping the 3.1 from my 92 GP?

[3100 MPFI]

easier that swapping the twin cam in place of the pushrod.

You can use the same tranny from the dohc. I would recommend the DOHC tranny because it is electric. I think the 3.1 didn't get the E tranny until 1993.

Use the DOHC tranny, you already have the area to mount the engine. There will be wiring, of course. Exhaust downpipe. Coolant lines.

You do the E tranny, you will want to use a 1993 ECM.

You have a parts car, so doing it is not near as bad as if you only had the engine. Having a parts car made it a lot easier to convert my 1988 Cutlass Supreme to OBD2, and 3100 SFI.

[TazMan]

Thanks for the reply. I've seen alot of real cheap DOHC GP's around here that need motors. I was also looking at one that already had the motor and tranny gone too. Are there big benefits to having the 4 spd electric transmission as opposed to using the 3 speed in my GP?

[3100 MPFI]

as heavy as the GP is, you will want the 4-speed. It was made for that car, and will be easier to get in there.

The 4 speed and parts are easier to come by. To be honest, the only W-body I have seen with a 3 speed is the Lumina. Not saying that they did not do it, but the 4 speeds are more out there, and easier to find.

The Electronic transmission has the advantage of being able to have a chip made with custom shift settings. The 440T4 (4T60) is harder to control, and I don't think it can be tuned like the 4T60-E can.

I understand about using what you got, but at the same time, you might want to think ahead some. Are you only doing this for a decent daily driver? Or will you want to do some performance things too it later. If you plan on modifying the car, then you will probably want the 4 speed. I know Ben can tune chips for the 4speed. He has done it for me, and I was really happy with it. I never asked about the 3 speed because I don't even know if that did an electronic 3 speed.

Or did you mean 5 speed?

[TazMan]

My GP has the 3 speed. It is a very good running car, but the body could use some work, so I've just been weighing out my options.

As far as mods, I already have waiting to be bolted on, 3400 heads, large port ported 3400 manifolds and a 65mm TB. I think this will probably be good enough for my needs. If I'm still not happy with it, I might consider looking for headers, but that would probably be it.

If I do go this route, I'll definitley take your advice about the tranny. I'd like to be able to change my shift points. I assume I wouldn't be able to use the DOHC computer so I'm guessing I would need one from a 93 GP with the 3.1l pushrod and the 4T60-E. Is this correct?

[3100 MPFI]

correct.

You MIGHT be able to use the twin cam ECM, and a 3.1 chip, but I can't confirm this. Best bet is a 1993 3.1 4 speed auto ecm. There are others that can confirm if you can use the twin cam with chip. I used the 1993 3.4 DOHC ECM in my 1988 Cutlass Supreme originally, but I had a custom chip for it (and a custom engine).

To be certain, kinda need to know the year of the car this is going into. One thing to consider is that with a lot of state, the engine has to be the same year or newer than the car. Meaning if your DOHC car is a 1995, you might not be able to use the 3.1 without the 3400 heads. At least with the 3400 heads and intake, you can pass it off as a 3100 swap.

Friend of mine swapped a 1987 SBC into his 1995 camaro, and they would not pass it. As soon as they opened the hood, and saw it was a carb engine, they said FAIL and pulled his sticker, put a note in the computer, and made him TOW the car home. They would not let him drive it off of the shop lot.

He replaced the SBC with an LS6, and they passed it.

[GPXSS]

you will want the hard coolant lines, motor mounts, entire engine wiring harness up to the firewall with ECM, dogbone mounts, power steering lines, downpipe w/ cat, A/C compressor lines, and radiator hoses.

all of these changed when i went from a 93 3.1 to a 95 3.4. Be aware of year changes with wiring (specifically the firewall connector pinout) if you go 94/95ish

[3100 MPFI]

yeah. Firewall wiring is a big deal. If you get a 94-96 Grand Prix, then you will have a lot of wiring on the INTERIOR. I don't even know if you can get the newer interior wiring to work with the older engine. You would probably have to use the 94-96 engine wiring, and install the 92 engine, then repin the ECM connectors. I think that would be easier than converting the newer interior wiring harness.

I just rewired my firewall connector to use the 1993 INTERIOR, and the 1996 ENGINE, but I don't know how to get it to go the other way.

[86euro]

Friend of mine swapped a 1987 SBC into his 1995 camaro, and they would not pass it. As soon as they opened the hood, and saw it was a carb engine, they said FAIL and pulled his sticker, put a note in the computer, and made him TOW the car home. They would not let him drive it off of the shop lot.

He replaced the SBC with an LS6, and they passed it.

Was this the 305 car that I saw on camarosource? If so, I was wondering what happened to it. I suggested to complete the "dare to be different theme" and add Cross Fire Injection.

[3100 MPFI]

no. My friend did it all before he was killed in a car wreck, but never got anything about it on the internet. Unfortunantly, after he died, his family junked the car. He had pulled the LS6 to do something to the cam, and never got it finished. They did not know how to fix it. Also, he was doing some body work to it.

[FiredUpZ28]

GM had a good idea with the DOHC V6. But they put them into production too early before they could find all the flaws, tanked, then basically stopped until now again.