boredguy77

would a mkiv to sc300 auto swap be direct? I hear that the mkiv auto can handle up to 500hp and that the NA can only handle 350hp, so if this is a direct replacement this seems to be the most cost effective. I would really hate to limit my sp60 to 350 to accomodate the transmission.

psychot|K

uhmmm i dunno...i've heard the MKIV TT tranny can't hold that much. yes it can hold 500 but for how long is the question? at that power level i hear it can't last longer than a few months. you could be smart about it and get a torque converter and a HUGE tranny cooler with some nice tranny fluid and regular changes, but i don't see how it'd be worth taking the risk. i say just get soundperformance to re-build your tranny. from what i hear on the supraforums they do GREAT tranny work.

boredguy77

Yeah I have heard that their trannies are great and they just released a new one that can handle 1200+ it is the sp400. lots of the big single guys are real happy about that. I know that a SP tranny would do me well, but the $2900 price tag is not in my pocket! I wonder what the life is on the MKIV at these power levels? does anybody know? If i have to I guess I can keep the boost down.

psychot|K

yeah it does have a high sticker price and yeah it's the SP400...perhaps ripping off the domestic turbo400 tranny :P

but the stock auto with NO mods, at 500hp would last a few months. some guy said he used up 3 in the last year at around that power level. anything more and he said they spontaneously combust. and don't even think about upgrading the clutches...apparently that's a great way to blow up spragues.

boredguy77

so my options narrow down to
1.) spend the cash do it right, and get the upgraded SP Tranny.
2.) run the car at almost half of its potential and limit it to 300 HP?

psychot|K

what i would do is this...it'll be way cheaper than the SP400:

1) run amazing tranny fluid...something for performance, ask the folks at royal purple or redline, their high performance lubricants are used in most high horsepower cars
2) do frequent tranny fluid changes
3) get a stall converter
4) get a valve body modification done (helps reduce the #1 killer of auto trannies: heat
5) MOST IMPORTANT: find the BIGGEST tranny cooler you can with a fan on it and mount it in a place with high airflow...you gotta keep that tranny ice cold
6) be smart...don't break boost 10times a day for 1min at a time. if you gotta break boost do it for 10 sec MAX.

with those guidelines you should be happy and in the safe zone. just don't push your car 10 times a day and when you do be smart about it and keep the tranny in mind. if you WANT to run 500+ consistently and drive your car hard then you have NO CHOICE but to shell out the cash. the above guildelines will only increase the life of the tranny at high power levels...by no means will it allow you to hold 700hp like the SP400(for longer than a week anyways).

Onelove

Or just put a real Turbo 400 in it with an Adapter plate Your going to have to open up the tranny tunnel anyway, might as well put a tranny in that any race shop carries on the shop (it's nice to call summit or jegs and have a tranny the same week). That and the chevy trannies have been proven to hold big numbers over the past few decades. I'll show pictures in a few weeks as we are currently doing this to an old SP tranny equiped Supra that's tranyn didn't like the 750 whp it was putting out.

psychot|K

i'm not too familiar with the power handling of the turbo 400. how much is it and how expensive is it to make it hold serious #'s? like 1000hp.