SC400 to be faster then 400hp Vette?

[jibby]

This is probably a stupid question, but my goal is to make my 1992 SC400 run as fast or faster then a new stock 400hp Chevy Corvette that does 0-60 in 4.3 seconds and the quarter mile in 12.7, and also beat the slower E55 AMG. Can it be achieved or am I wasting my time and money working around this stock tranny and internal engine parts? However, last I raced I did stay close to hanging but lost to the all mighty American muscle Vette with my old Betsy SC running nos, now with much wider rear tires and rims on the way, fine tuning, headers, and minor electrical upgrades I am hoping this will bring me even closer.

My ultimate question to you pro's is can I achieve this goal with the stock auto sc400/soarer tranny running the LSD and D.T.C? Or do I d need to swap into the manual V160 to even consider achieving the 4.3 and 12.7 times with the Sc? I know I can get this motor to produce the power needed but tranny shifts and hp tranny capacity is my worry, Is this a pipe dream?... I have raced a new vette one time a few months ago and lost but I did hang with the vette once we got going riding the nos but could not catch or pass, and I did get badly destroyed off the line. I was amazed at the off the line traction these new vettes possess, you would think they were AWD, but hopefully and just maybe that will change with my wider tires and coilovers to be installed shortly. Any thoughts on my delema???

 

[Anaema]

im no pro, but a manual conversion will definitely help alot. the torque converter that an automatic uses saps more horsepower than a manuals clutch and gearbox. you dont absolutely need to swap, but you will need less HP at eh flywheel with a manual than you would with an autobox.

there may be only a few things a Corvette has that give it such good traction; big, fat rear tires, and an LSD. other than that, all you need to do is get more HP and figure out a way to drop some weight off the SC400. a light flywheel and clutch combo and a custom aluminum driveshaft should do the trick. it means more HP to the wheels because the engine doesnt have to use as much to spin all the driveline components. it will also allow the engine to rev faster. a lighter wheel and tire combo can have this same effect. so does lighter internals.

that took more words than i thought it would....

 

[jibby]

Anaema- Thanks for the reply and your thoughts, but I have already uprgraded to a Dragon Torque Converter, Supra torsen LSD, and now fatter rear tires with a soon to install coilover suspension....that will cover my traction issues. I am done unless someone produces a AWD swap for the sc's, now that would be sweet...and very tough to beat....I have experienced all wheel drive in a turbo C4 porcshe, and many off road trucks and it really is amazing and would make a difference..

Back on subject I just hate the idea of trying to swap in a manual tranny on this automatic sc400 car, sounds like so much work, you need to create a clutch and pedal system, that includes mounting a solid foot pedal system and shifter where it will fit and work with the stock look, and I am sure there are a list of other suprises that pop up in a swap of that magnitude... Just would rather spend the cash and find a way too beef up my current stock tranny and drivetrain to handle a stronger load and perform with better timed shifts. Anyway, I have been looking into it and am starting to create a few options for myself. That is also why I post threads like this one. I spoke with a pro tranny specialists last week and they say beefing up the tranny can be done...Larger valves, etc.. and $$$.

The aluminum drive shaft which you mention I have not heard of, I thought I would have to upgrade to a stronger and larger steel driveshaft if anything. I must say I have considered a complete Chevy rear end swap which I am very familiar with and think I could pull off. In any event I really am trying to keep this car an import car only, and not mix in Chevy or Ford stuff which I feel is cheating, (including American forged pistons and rods) I really have been tempted though...Believe me I can weld I am a contractor, I grew up on Chevy's, infact my fist car when I was 17 years old was a Chevy Nova SS, it had a TH400, 350 small block, Detroit locker with limited slip capabilities, headers, Edelbrock intake, and 4 barrel Edelbrock carb, MSD, the works. I could of produced 600+ hp if I would have had the money and time back then to put into it, but I didn't, and then later sold it for a 4X4. In any event I did have that SS Nova (heavy beast of a car) motoring very well back in the day and that was even without the forced air induction on it..like a american blower..I guess 5.7 liter motors or larger just simply produce the juice...

Anyway back on subject, I wiil read and search for more advise, and I will continue to push the limits of my stock engine and tranny til something snaps, sorry for the story.....See ya

 

[T_Terror]

No way, a worked auto will always trump a manual in straight line speed.

Key word there is WORKED. ANy stock auto will always be lagging behind a good manual driver due to slow shifts and less than ideal ratios (Falcon 1st gear anyone?)

Also i have not heard of anyone making high stalls to suit toyota autos, maybe there is in U.S?

Easy option would be to swap in a V160 though yes

 

[jibby]

The V160 and the adapter plate group buy is an option but not an easy one from what I can tell, no way!!!!!!! I searched and found no write ups on actual Soarer/SC400 swap to manual, and if so no pic's to show how clean the swap worked and looked.

However, here in the States, and especially here in Los Angeles, Ca. there are a great number of import transmission shops, and even a few high performance tranny shops that claim they can open up the stock SC auto tranny and build it up to handle more power, drive shaft upgrade no problem. I forgot exactly what they said, but one shop said larger valves, another something else. Also was told a good Stand Alone ECU will help with better transmission shifts. Although I don't think I am going to a stand alone. Anyway, I know there is a way to modify the weak points to the stock Soarer/SC400 transmission, like 2nd gear blowing out at around 450-500hp. I am sure it will not be cheap but I know it can be done......If there is a will there is a way... That will be my next quest after this header install. I am on a mission....Example, the 500hp E55 AMG Mercedes is fully automatic and the stock Vette 400hp automatic tranny's are most likely built to handle 600hp+ If these cars can why not mine?

 

[TundraEddie]

Back on subject I just hate the idea of trying to swap in a manual tranny on this automatic sc400 car, sounds like so much work, you need to create a clutch and pedal system, that includes mounting a solid foot pedal system and shifter where it will fit and work with the stock look...

Pedal assembly etc. from a 5-speed SC300. MkIV Supra parts may work too.

 

[Anaema]

a well built, light weight aluminum driveshaft can be custom made by a driveshaft shop. it should be able to withstand 500+ HP. it will help with the cars reaction time.

 

[jibby]

TundraEddie- Good point on using the sc300 and Supra stick, clutch, cables, mounts, etc... , but still I would think there will be alot of fabricating and alterations to fit all this in the auto sc/soarer, maybe I am wrong. I would love to hear more about the specifics of a manual V160 swap, pics, resutls and testimonies if any. I can see how the sc300/ Supra might hook up fairly well, but still floor board cutting is needed and is there even enough room to fit all this clutch stuff in the sc400? I would be very suprised if it all just mounts right up. Do you think anyone has even tried this swap yet, or is all just up for discussion for the supra's and sc300's only? I have searched the forum history threads on this subject and found no such swap to the sc400/soarer auto. Just alot of talk about adapter plates, other car swaps, etc... I would think this V160 swap would be alot more doable in a Sc300 or Supra that already has the clutch system installed, what do you think?

Aneama- Aluminum driveshaft can handle 500+ hp? Did not know......

 

[Anaema]

custom aluminum driveshafts are used alot in Horsepower TV in high HP drag machines, around 600 HP i think. ill look it up just in case.

if a Mustang that has enough HP to lift the front wheels off the ground uses an aluminum driveshaft, so can you. for some reason Firefox wont let me post a link, or i would give you one.

 

[WDoherty]

jibby, go to the powerhouse racing website and you will find the supra tt auto built to more hp than you will need for $1800, as for shift points, those guys are experts and might be able to point you into the right direction for transmission control
p.s. man, it sounds like you do alot of racing......are you doing this on the street? how do you find all of these willing participants? have you done a track run to get a baseline of what your running?

 

[rdm20fan]

Hey Jibby. Chris and I have done alot of work the the stock trans. I don't think you will reaonable be able to get the stock trans in the SC to run 0-60 in 4.3 seconds. I do think with some work you can get it to run a 12.7 in the 1/4

I have an autometer D-pic, and when my car was running it's best the D-pic claimed a 12.8, but it was at 125MPH the vette does the 1/4 at a trap speed of around 110mph. my 60 foot times bested a 2.2 most were 2.4's

I have a completly rebuilt the trans with rabestos blue friction plates, koleen steels, 22-2600 stall torque converter, raised line pressure, and a couple tricks to get the trans to shift pretty hard. I've chirped the tires in 2nd, and 3rd.

a TH-400 should be able to get the car to get up to 60 in a quick time if you want to stay with an auto, but you will probably loose some drivabilty.

I think the aftermarket support isn't there to cost effectively make the SC launch hard, but I do think it can handle some good HP #'s to run a fast 1/4 time.

 

[jibby]

WDoherty-I will check out the powerhouse website thanks for the tip. As far as racing goes, yeah, I do somehow find street races rather easily and often, why? There is a long empty street that connects Marina Del Rey to Culver City, in Califonia and there is only two lights on a very empty 2 mile stretch. Just so happens a lot of nice new sports cars, luxury cars, etc.. drive this road to get to their rich homes in Marina Del Rey. I just head over to that road when I am bored or on my way somewhere and find a race, especially at nights and on the weekends. People who drive that strectch know it is safe and empty which runs along next to a freeway. This two mile, two lane smoothe stretch just invites races and you don't get tickets, thank god. Secondly, when my SC pulls up next to a sportscar it draws attention with the deep rumble straight thru exhaust and the lowered racing rim and tint look. They can't resist, if I tap the gas playfully at the red, it's usually a go, and often these people driving these fancy new cars don't take a 1992 sc400 too seriously even with the rumble sounding exhaust, so the light turns green and most juice it, but some don't. I love suprising these guys with my ride, to me that is the best part besides winning.

I also can spin the rear wheels forever in first gear and go nowhere fast if I ride the nos from a dead stop, I try not to hit it until 2nd gear then the rears will spin just a bit and I am gone. I have had the chance to race a Viper, turbo Porches, vettes, M Beemers, amg's, you name it.. and I have backed down alot against the big boys. The funny thing is I don't go out looking to race very often, but with this car and that street it just happens, and the nos is always armed just incase. That is the end of this long story...

 

[jibby]

rdm20fan- It sounds like you know exactly what I am trying to do, and then some... I did figure it would be very difficult to break that 4.3 second 0-60 with the sc stock auto tranny, that is why I posted the thread to begin with. That is fast.... but I would be happy with a 12.7 in the quarter.. As far as doing a Th400 tranny swap, I don't want to do an American racing tranny, I want to stick to the import tranny, although I have thought about it a few times...The Th400 does not shift quiet as smoothe as the stock sc tranny, so I would probably go V160 manual tranny swap before the th400, I still am spoiled with the luxury driving I guess...

This does sound promising on what you said you did to build up your tranny, how much hp was your tranny supporting after the upgrades? This is the info I was looking for....I may be pm'ing you shortly, I hope you don't mind...

Thanks for the replies, very insightful.......

 

[WDoherty]

Sounds like a conducive environment to high end street racing, nice, i can't imagine, I live in West Texas. Anyway, besides the transmission thoughts, are you going to go for cams?

 

[jibby]

WDoherty, Yes living in the big city for as long as I have, you find the streets and fancy cars.

Cams- I have had my eye on those Kelford Cams for a while, but I don't think the stock tranny can handle the additional 40-45hp gains, with that upgrade I may just blow out my second gear. This is why I wan't to upgrade my tranny....and yes cams, heads, forged pistons, rods, etc... would be next...

 

[Anaema]

you could do Extrude Hone on the intake manifold and heads too, that should improve flow a bit.

 

[jibby]

Anaema- I am interested in this Extrude Hone process on the intake manifold, how is the process done, and what gains are to be expected? You also mention the heads as well, I am guessing it is like porting the heads. Is this what you mean?

 

[Anaema]

the Extrude Hone process takes a putty like substance with abrasives in it and uses hydrolic rams to shove it through the part at high pressure. it flows through normally until it meets an obstruction, then the abrasives cut it smooth. it works better than port and polishing because it can be flow matched, which apparently is really hard to do with porting and polishing. with both extrude honing the intake manifold and heads, and polishing the combustion chambers, you should be able to get some noticable gains. i dont know myself, because ive never had it done(i dont have the resources), but i have researched it alot, and you will definitely get HP and torque gains.

 

[jibby]

Better then porting and polishing? I will definetely have to look into this, thanks for the tip.....

 

[Pro]

don't bother with extrude honing. all it does is make the ports bigger and cleans them up a bit.

you need four things by the sounds of it.

boost
transmisson
diff ratio
tyres

you can modify the toyota autos to be perfectly seamless between first and second gear shifts by upping the oil pressure significantly - the only way you know it's changed gears is the change in engine note.

this will make for a reliable transmission as you have removed the shock loading from shifting. you have also got a zero second shift time > you should also use overdrive in a manual arrangement (ie DISENGAGE IT).

to get a 12.7 quarter mile out of an SC400 isn't a big ask - people are fitting T78s with 20psi to stock 1JZs and getting these times so i don't see why you can;t do the same with a 1UZ.

i would fit a big turbo and start running with about 1bar (15psi until you're confident) to a stock-but-good-condition 1UZFE. gradually wind up to 20psi as your racing improves but this is the limit of a stock 1UZFE with god tune and effective intercooling ( a good W2A and water injection a must here). run individual coils from a honda CBR motorbike and CDi ignition to ensure good spark. (see the coil-on-plug thread under FIAT) you will need aftermarket management for this and a fuel system to match.

fit some cams to take advantage of the higher revving nature of the engine now - go for around 270 duration for the inlet and around 280-285 for the exhaust. but the trick is to get AS MUCH lift as possible without running into bucket/shim issues - aim for a reliable 9.5mm (around 375thou). any more than 400thou (10.2mm) lift and you will be breaking valve guide bosses and fouling on the bucket. this is a big prob with toyota engines running big lift (and nissan engines too) using a bucket and shim arrangement - ask any serious 2JZGTE racer!

diff ratio affects 1/4mile performance a lot - aim for 3.7:1 gears or higher.

and fit sticky road tyres or slicks.

aaaaaaaaaaaaand i reckon you'll be running high 11s in no time depending on your reaction time.