SC 14 swap

[M.Bailey]

what do you need and were do you get it? does the SC14 come on another car? and how hard is it to swap to an 88 SC. ECU changes? wiring harness changes?? I"m interested in doing this in the future. about the time after I can put like 500 miles on my current set up. thanks for your help

[Jackstand Queen]

The SC14 is cheaper and easier to find. Some Jspec importers have them laying around like Makoto Motors in Kalifornia.

The 14 is a very poor fit in the Mk I engine bay. You have to grind and cut the intake manifold, and J-pipe. to make it fit. You have to have an SC12 oil resavoir end piece to put on the 14. You have to have the inlet and outlet pieces cut and welded together with pieces of both 12's and 14's coming together. Or you could totally fab customized pieces from scratch. You need to cut off the bottom SC mounts and relocate them to match the SC12. This is about the hardest and most critical fab job. Too high, too low, too far forward or backward, too close to the block, too far and it won't work. You'll need a new SC belt too most likely. You'll have to dissassemble both 12 and 14 clutch pulleys and move the portions of the 12 stuff over to the 14.

Also the ABV will interfere with the 14. It will need to be modified to fit a whole lot closer to the Jpipe to fit. Or better yet, use a Bosch ABV. The Jpipe mounting holes will need to be reemed out to allow it to bolt on cocked at an angle.

You will need to fab in custom made upper mount braces that go to the intake manifold.

The stock ECU runs the 14 fine. I recommend either higher pressure fuel pump, or 10 to 20 % larger injectors . . . but not both.

Overall its a buttload of work. To me it makes more sense to put in an SC14 rather than spin an SC12 faster with oversized main pulleys. With my N.A. throttle body mod I reckon, I'll get 13 or 14 PSI. I was getting 12 with the SC Throttle body. I could always get 10 PSI instantly above 2000 RPM.

Overall I can't highly recommend this modification. Its a lot of work, with lots of pitfalls. Cost wise, the welding and ABV replacement drive up the cost. And you can increase an SC12's boost with oversized pulleys.

However, pristine, low mileage SC12's are mythical beasts. Parts to rebuild SC12's not available as far as I know. New SC12's from the yota Dealer were 2 grand, last time I checked. And perhaps not available even at that price.

Viewpoints and opinions differing with this post are encouraged. I'd like to know if I got some of my facts wrong.

[kramerbuccs24]

^good info there

[Jackstand Queen]

I forgot one important aspect of swapping in a SC14.

Its the welding of the lower mounts on the case . . . . . the welding process has a tendency to WARP the case to the point that the rotors won't turn inside.

This happened on my first SC14. So I pulled the case apart and honed out the humps and it worked fine, for about 1000 miles. Then I started getting a loud clicking noise, which I believe was caused by the SC. Its possible that the case warpage I had ruined the SC, or I might have had the belt on too tight. I suspect it was the case warpage at fault. In any case, the SC12 and 14 are not built for the main internal parts (Rotors) to be pulled apart and put back together. The rotor shafts have press fit bearings. They require hundreds, of lbs of pressure to remove and re-insert them. Its likely that this process damages the bearings.

So, I am in the process of fitting a 2nd SC14 in. I've noticed that anything less than a very snug fit of the lower mounts onto the block mounted SC mount, causes the rotors to bind, just as if the case had been warped by welding.

One of the welders I worked with suggested filling the SC14 case with water while doing the welding work. To prevent warpage. Other welders believed this wouldn't allow the metal to get hot enough to create a strong weld. The answer to this issue is answered on the next and last line.

It sucks to be me.

[random_tox]

Originally Posted by M.Bailey

... does the SC14 come on another car? and how hard is it to swap to an 88 SC. ...

I've been curious about this as well. Would love to see the dyno chart from a completed project.

I think the SC14 came exclusively on the '94-'97 Previa Van. Toyota Previa - Wikipedia, the free encyclopedia

[mhamrick]

Jack Stand Queen- Did you not just get a low mileage, pristine SC12???

Also if you are going to buy a large pulley for the SC12 the NST is not necessary. Technotoytuning has a nice one with a stronger reinforced keyway and at about half the price of the NST. Also they use a belt that all auto parts store or can get for you cheap. This helps because NST is NOTORIOUS for not answering your emails and making customers wait 6 or months for parts.

Here is the T3:

Techno Toy Tuning - Your performance parts source for the old school cool!

[Jackstand Queen]

Jack Stand Queen- Did you not just get a low mileage, pristine SC12???

Yes, as I matter of fact I did obtain a JDM SC12 recently. It's internal parts are still in very good condition. Its now offically part of my SC14 fail plan. If I can't get an SC14 to last more than a thousand miles . .. . I'm going to revert back to an SC12, and put a larger main pulley on.

Incidentally, I took a part off that SC12 from Japan, put it on my SC14, drove it yesterday . . . . and discovered that my SC Relay was bad. I had a spare SC Relay laying around, but it turns out it's bad too. There's a single rectifier, or transister inside these relay's that went south. Since the Yota dealers won't supply new one's, its off to Radio Shack I go for a new rectifier and a tiny soldering device.

[M.Bailey]

I have been looking around lately and I stumbled across the Rotrex Super chargers they are pretty cool and compact from what I have seen they are neat because they turn the RPM of a turbo but they are belt driven and have the instant power characteristics of the SC unfortunately they dont make a kit for the MR2 however being that small I dont see how it would be that hard to adapt it to the current piping in an SC MR2 it would be interesting to see what kind of power they make. there is a few videos of cars with the Rotrex super chargers on youtube if anybody is interested.

[Jackstand Queen]

Sc12's are made by Ogura Clutch Co. of Japan. They are a roots type SC. Very old school and less efficent than Whipple type SC's.

Are the Rotrex's whipple types? Their insides look like giant air screws.

[div0]

Originally Posted by Jackstand Queen

Are the Rotrex's whipple types? Their insides look like giant air screws.

No, the Rotrex superchargers basically mate a turbo-like compressor to a belt driven system. Planetary rollers are used to get the compressor to spin in the high RPM range.

This means that the Rotrex superchargers are not positive displacement like a twin-screw or Roots type supercharger. So the boost is not constant over RPM with the Rotrex, but tends to increase with increasing RPM. You won't get the same initial low RPM torque like you will with a positive displacement supercharger, but the boost will increase fairly linearly with RPM which is much more predictable than the spool of a turbo.

Some people like how the linearly increasing boost tends to offset the engine's natural falloff of volumetric efficiency in the higher RPM ranges.


-div0

[M.Bailey]

yea what he said

[Jackstand Queen]

I've gotten kind of fond of 10 PSI . . . on demand . .. . available in a fraction of a second.