transmission?

[grandamsev6]

i' d like to know by how much hp can i boost my engine before making a transmission swap? i have a 99 grand am v6 automatic


thanks!

[coupe]

No one really knows for sure.

Chances of you getting there anyway is slim to none.

[vainot4u]

Has anyone taken the 3400 GA to it's extreme? I mean it seems like you'd have to do engine internals before the tranny swap would have to happen. I plan to do the RSM supercharger and they guys at RSM seem to think the stock engine/tranny can handle it just fine. On a side note the stock G6 uses the 4t45-E which is what we have stock, however the GTP uses the 4t65-E (or so I am told)...

That brings me to my question do the 4t45-E and 4t65-E have the same bolt patterns? Can you "easily" fit the 4t65-E into a GA?

[Nacho]

no the 4t65e wont bolt right up it will need some fabrication to work.

[MantaGreen97]

The 4T65-E (now just called the 4T65 as GM dropped the Es nowadays) will bolt up to the engine fine I believe. The 4T60 bolts up to the 3100/3400 in many other vehicles (pretty much all modern GM FWD bolt to the transmission the same). However it's the driveaxles that don't fit right on the 99+ GAs. Those need to be changed and there needs to be a little modification, IIRC.

It can be done--someone put an L67 in a 99+ GA and they had to use a 4T65 obviously--but it just doesn't swap right out, unfortunately. I don't think it is too hard to do though.

As for how much the 4T45 can take--I wouldn't push it really, it's at its upper torque limit already, in stock form really. (Interestingly GM themselves have used the 4T45 with engines with higher torque than it is specified for; however, it's still not a good idea to push it too far. There are places that have heavy-duty rebuilds of GM FWD transmissions, so you could check into that as well.)

[vainot4u]

Thanks for the info! I have found the 4t65 in the racing form; it was bosting being able to handle 1,200 HP and fluid shifts at 10,000 rpm!!!!!...although I doubt ANY late model GA could get there...

I guess I will have to do something with the tranny before boosting the engine, probably more in the form of a heavy duty rebuild. Do you think with a heavy duty rebuild the 4t45 could handle 250-300 HP? I just want to measure what the limitations are on the stock 4t45...I know there are other variables to look at...only concerned with tranny at this stage of the game. Thanks for any info.;)

PS here is a link for the 4t65 racing tranny (http://gmtunertour.com/index.asp?section=B592A7DF2B4D41A78CF337DADAFAA851&page=55CBA209F13F467ABBCA030DD03F98F5)

[tejohnson]

If you are only lookin at 300hp, then the 45e can take it just fine with a decent rebuild and good programming.