Thanks fellas for the suggestions. I too know a little about tranny options and builds..Both of you are offering your honest advise let's not battle..The TH400 needs an overdrive if that is to be considered, and driveabilty will suffer.... Boost logic Lexus builds, tranny cooler, (upping the line pressure which I already did), is the cheapest build for my situation and also it is a good choice for additional hp holding capacity needs for the money being spent....I just don't see how that is going to help with shift speeds and times when the ECU really controls alot of the tranny shift and times..

Anyone ever try A triptronic conversion yet?...

HP Auto Trannies -Even the new Vette auto trannies have weak HP holding capacities when looking into them.....Boostlogic built Sc400 trannies get mixed reviews also...

My SC400 engine power goals are too pump out a true 230-240whp and run a true 150HP open dry NOS shot.....I am just about their now with my recent dyno at 201whp running on just the stock ECU...(I Got cams in the works now, and a new ECU piggyback is on the way in the mail)...I am looking at 350whp or so as my final goal unless I decide to slap a single Garrett exhaust turbo in and dump the nos altogether..Which might very well happen then I would shoot for around the 500whp. Thinking about that as I finally got the help I need to get it done, and a blue print on how to do it.....I would just hate to dump my headers I just installed recently......

Anyway, The stock Sc400 automatic tranny can handle the 350whp I believe with a cooler, upped line pressure, etc..Holding capacity is not my major concern for right now, it's the timely shifts.... That is my delema.....

Boy, o boy skeet, did I hit a nerve? At NO point did I mention anything about your background...I did not come from a wealthy background either. Why did you bring that up? You on the other hand, were very quick to imply that I did not know what I was talking about and "sugguested I research built autos on supraforums".

I was simply trying to give Jibby some honest, real world information based on HIS criteria. One of which was not spending too much money...that would rule out a th400 swap & GV unit. I do agree, that the combination of the 400 & GV would be killer, but will be over his budget!! Yet, you kept pushing it on him.

Second, at his projected power, unless he plans on drag racing it weekly, I really dont think he'll want to undertake a 400 swap project. 240rwhp is not much, even on spray @ ~390rhpw, not much! There are plenty of Supras running built toyota automatics at 400rwhp all day

I dont have to build his trans...based on what he wants to do with it - any good shop can!

Anyway...

Jibby - a few things will come into play for you.

Getting those quick & crisp shifts you want will have to do with the line pressure and the clutches inside of your transmission. If it's starting to go south, it simply will not shift as quick as you'd like. If you do decide to get it rebuilt, my suggestion is 2 decent sized trans coolers, each with fans on all the time the car is running

As for the ECU - I'm not sure if the SC is the same...but the Supra ecu will "let off" in between shifts to help save the tranny. The work around is pulling the trac fuse - it'll shift much harder - but but is more stressful to your transmission.

I truly believe you would be happier with a build SC400 tranny. My last thoughts to promote a happy trans is:

1) two coolers each with fans
2) do not "stand" on the stall, you mentioned running nitrous. Letting the car leave on nitrous is much easier on the TC than standing on it Even better could be using a progressive controller on the nitrous!

Progressive nos shot is needed for sure...I cannot leave the blocks riding the nos, so the tranny does get a good jolt from nos in 2nd gear when activated.....I always need to wait until second gear to ride the nos...My first gear with the combination of a Supra LSD, Presicion Industries Dragon Torque converter, Light weight rims, fat and short low profiles, etc.. I get a really good 1st gear launch always with this setup ever with just the 200whp and no nos......If I hit the nos with anything over a 50 shot I will just spin both tires out like crazy in first gear and go nowhere fast...Under a fully heated 100hp+ nos shot I even have some traction issues in second gear at lower rpms...Luckily, with the addition of the S&S headers and the fact that some lowend torque was lost during that install I can now grip well enough in second gear under the juice and still get good power at higher rpms too.....I had some serious lowend torque going on pre-headers.. S&S Headers is all good for topend gains and a little lowend loss... Drivetrain setup is key and that is what I have worked on even with this measly 201whp and the nos system...

Thanks again for your tranny suggestions and I will use them...

Maybe you Supra guys can help me out...I am thinking about the 93-98 Supra TT auto tranny swap into the SC4......That tranny holds what 500whp or so?, The car has the same sub frame as the SC400, I am running on a 95 Supra LSD Now..

I am wondering if that Supra TT tranny would bolt right onto my SC4 and accept the transmission codes from the stock SC400 ECU?....Or can the Supra ECU be worked into the SC400? I dought that.......

What do you guys think of that swap? Is that a good idea?...I know I can pic one up tomarrow for under $1000 at a local junk yard....Those Supra TT auto trannies are built to perform and must be an overall better tranny then what is in the SC400's...right?

this just in... the auto sc400 transmission is the same trans code as the toyota supra turbo transmission
A341E

Applications:

* 1993-1998 Toyota Supra turbo
* 1992-1997 Lexus SC400 4.0L V8
* 1992-1998 Lexus LS400 4.0L V8
* 1993-1997 Volvo 2.6L I6 (AW30-40LE)


per wikipedia...

I plan to get some work at IPT in the future...not too happy with Lexus trannies either in the performance department.

Lexmet - The auto Lexus trannies labor at times in my opinion...They were simply built and designed for luxury and longevity and not for performance, which is understandable.....However, wIth the ECT button on downshifting is some what quicker but the RPM's drag out far past the power curve.., and when the power is up these cars the shifts become long and drawn out and labored at times... That is why I must seek out the path of least resistance and swap away asap.... No point on building a motor for more power if the tranny is not going to perform with it...Very counter productive in my opinion...

I am going to search out swap info on this A34!E Supra TT......This was mentioned in an earlier post in this thread..Thanks... So it seems to me it just bolts right up to the SC400 with no significant mods needed.....No adjustments or alterationions are needed at all? That would be amazing if that is true... I could swap in that tranny myself in my backyard in a day or so.....Could it be just that easy to swap in from the Supra TT? I think I am dreaming? There has got to be some moding involved...

Time to use that search function, if you guys or anyone can shed some more light on this swap I would be most grateful...

If your stuck on getting away from the lexus trans, don't go TH400. Those are only good for strip cars that see a little street time.

Lower hp, you can go 700R4(4l60e). these when built will proably take 500 hp in rwd form all day long. The 700r4 from my typhoon has a specical valve body GM put together to be quicker shifting than any of the aftermarket shift kits. The shift from 1/2 in the Typhoon will cause neck damage if you're not paying attention.

Or if you want BIG hp, go 4l80e. Both trans have a 4th gear, and its a low one at that to save fuel when at cruise on the freeway. Parish has a Turbo 6.0 Truck running 1000 hp on a built 4l80e.

It sounds like the 93-98 Auto tt A341E tranny swap is a go for me...

Spin -Thanks for the suggestion and I did look into the 700r4 also, just too much involved in that swap..

I am looking for the path of least resistance in regards to an upgradeable tranny swap....

why don't you just have the stock trans built... a built stock sc4 trans will be stronger with faster shift times than a stock supra trans...

Mits -I have heard mixed reviews about the boost logic stock built trannies for years..A few have even dumped them for the V160's...I feel a Toyota factory built tranny will always have greater performance and reliabily in general then an inferior built up tranny....I don't think I will be pushing much more then 500whp anyway on this car...I am having fun right now with 300whp or so.....200 more additional whp would really do the trick for me.... I also think anything over 500whp is really just over kill for a street driven SC400 in my opinion...If your on the track running slicks and shooting for records then the V160 6 speed would be the swap of choice for me, and yeah then 600-800whp + could possibly be manageable......The speed achieved in a car has alot to do with the drivetrain gearing and traction and in most cases even more so then just the horsepower being put out.. Especially after the 300whp mark... A 500whp SC4 geared perfect with a Precisions Industries Dragon Torque Converter, the Supra auto TT drivetrain and a few other light weight goodies like rims and fat tires would be hard to beat period. I don't see many cars on this forum beating that...Don't you agree? I need 200 more whp and the Supra auto tranny to get that goal achieved...

Don't those 93-98 Supra TT's automatics run at around the 300whp new at stock and do (0-60mph in the mid or high 4 second range?) See where I am getting at here?

I've heard of the Supra autos letting go at even BPU, and they do not take well to anything over about 400 hp stock. But I'm pretty sure they're the same internals as the newer sc400 trans. You should look into having John at IPT build you something. This guy knows his ****, and has built weak sauce DSM auto's to take 9 second passes. I would throw his work up against anything to come from toyota stock any day of the week.

This is along my lines of thinking...

my friend with a Boost Logic tranny, stock twin / stock side mount supra was easily in the 11's on drag radials, and went 11.10 with a 50 shot... his car, sans nitrous, dyno'd 440 whp through the auto tranny...

i don't know of reliability problems from Boost Logic, but, if not, then I know IPT does real good work as well... keep in mind, any built tranny was built for a reason, to take abuse, and the level of abuse will change from car to car....

as far as internals, if a built supra tranny can take it, so can a built lex sc4 tranny...


I do agree that 500 whp would be just fine for me, and one day, that's what I'll shoot for... I've already been there in my DSM, just time to do it in a slightly cooler car

Well the Supra TT auto tranny comes factory with more clutch plates and a few other goodies when compared to the stock SC400 auto trannies ... shift timing is better and this Supra TT tranny simply performs much better with a guaranteed 100whp greater holding capacity over the stock SC4's.....I may consider re-building the Supra TT auto tranny depending on what condition and how many miles the used one has that I get.....I would just elect to build that Sup tranny up locally to handle more Hp and abuse if needed.....Tranny coolers, etc... I need a good foundation to work with and the Sup TT auto seems to be a good cost effective place to start and swap...What is suprising to me I have not found one person that has performed this swap being that it seems so easy..I have searched Lextreme and this forum and found nothing....Increadible and shocking to say the least.......

Keep in mind I do not live in Austin Texas either where boost logic performs their magic on the stock SC4 trannies...Shipping and turnover time kinda stinks.....and yes the stock SC4 trannies can be built to hold bigger HP and more abuse definetely for what around $1800, but shifting codes recieved from the stock SC4 ECU will always be labored or atleast untimely...The supra tt Auto trans shifts electonically and runs independant from the ECu from what I have read and that is what interests me the most.....That is the secret for a better performing automatic transmission... The holding capacity can always be built up, it's the shifting times, downshifting speeds, etc.. that I am trying to improve on...

Thanks for the input guys this thread has opened up my eyes to a few things...

maybe u could try shimming the accumulators?