VJ-11 vs. VJ-14
 

Here's some pics for anyone interested in the IHI turbos. The VJ-11 (larger) was from a Ford Probe and the VJ-14 (smaller) was from a Mercury Capri. They look like the same turbine wheel but the VJ-11 has a larger turbine housing. VJ-14 has a smaller compressor wheel. The downpipe flanges are also different.

I've always wanted to compair the two myself but never had them side by side. Now I have the chance since I picked up a VJ-14 and mani for $20. I ran a VJ-11 on my Miata with a DIY mani. I could get 12-14psi all day but I could feel the power rolling off at the top end. I have a VJ-11 on the MX-3 now but it takes awhile to spool. I'll be putting the VJ-14 and mani on the MX-3 and let you know how that works out.

Attachment 214361
Attachment 214362
Attachment 214363
Attachment 214364

take off the compressor housings and measure the wheels for realz.

which manifold is that.....is it from the probe?

ok ok ok :fawk:

That mani is from the Capri. 1.6L (B6 I assume) but probably won't work on a Miata with the a/c and p/s in the way. I have the Probe mani also. It's for whatever that Probe had. 2.2L?

Ford Probe VJ-11 compressor inlet ID at the wheel = ~39mm
Merc Capri VJ-14 compressor inlet ID at the wheel = ~37mm

The compressor housings look identical but the Capri compressor outlet (for the hose) is slightly longer.

Both turbine wheels are ~44mm at the opening of the turbine outlet.
Both turbine inlet flanges are ~45mm and the same 4-bolt symmetrical pattern.

I'm not going to tear them apart again and figure out the a/r and trims and all that. Although I'd love to I JUST put them back together. I can't measure the wheels exactly due to them having an odd number of blades. Just allow for housing clearance of the above measurements.

does the VJ-14 have a larger exducer? because right now based on those numbers I'd go with the -11

lazzer clear your PM box man.

That capri manifold looks just like the 323 GTX manifold. I believe it doesn't fit, even if you have PS and AC removed because it hits the frame where it attaches to the motor mount...well the manifold may not but the turbo will.

Your probably right. It fits my MX3 though. Alot of people source these IHI turbos for DIY projects. I figured I'd throw some pics up since I hade the two side by side.

For what reason? The 14 should spool quicker on the 1.6 then the 11 would. I'm only shooting for 10-12psi on the 3 and I don't know if it'll even handle that. If not I'll go grab that engine out of the Capri. =)

edit - make that 8-10psi. That's more realistic.

if the turbine and a/r is all the same, you really wouldn't notice any difference in spool, but the large compressor wheel will prove better hp per psi.

I know the smaller turbine housing on the 14 lowers the a/r on that side. That should give higher velocity and faster spool in the turbine side of things. The smaller compressor wheel should give lower inertia as well. Together it should spool faster or at least at a lower rpm. I've seen how the larger compressor does make more power when I did the T4 compressor upgrade on my old T3 setup. Doesn't make sense though. Xpsi is Xpsi no matter how it's made and being that the T3 turbine/housing wasn't changed it shouldn't have had any effect on the exhaust restriction. It did take longer to spool the larger T4 wheel. Boost came on about the same time. Maybe the 14 turbine with the 11 compressor would work well together. :)

Going from a vj14 to a vj11 on a 1.6l GTX I had made the car not much fun to drive at all. It made good power but no usible boost until very high in the rev range. It’s not really a big turbo but spools like a much bigger turbo than what it is. I dont know why but it sucks. The boost response on the 14 is instantaneous and it will make 16+psi from 2500 rpm to redline with a good exhaust. You wont get much more than about 200hp but it will work at 20psi.

The huge vj23 turbo I have on the GTR swapped 323 GTX is also a total dog until it gets to around 4500 rpm then it tries to rip all 4 tires off as you have instant boost come on like sombody hit a switch. The GT3071R I have on the 2.0l Miata is a thing of beauty though totally smooth and gobs of power everywhere.

Bob

wow - you'd think the VJ23 would be more linear since it's a BB turbo like the gt3071r.

I would have thought the same thing. Both cars are very similar engine setup. The GTR is bored to 1.9l the Miata is a FM 2.0l. Both cars have an equal length tubular exhaust manifold with catless 3” exhaust, both putting out around 300hp but Way different power delivery between the two. It’s a good thing the GTX is AWD, because launch off the corners is like a slingshot you just mash the throttle mid corner and wait for the boost where the Miata requires a little more finesse with the throttle to keep it from stepping out the AWD just grabs and goes.


Bob

The vj11 on the mx3 now takes forever to spool. The 1.6 is a much smaller engine then the probe the vj-11 turbo came from. I think it came from an mx6 actually. What's is the probe a 2.4? I forget. Anyways, I can count the seconds it takes that 11 to make 6psi on the mx3. That's why I'm hoping the smaller vj14 turbine housing keeps the exhaust velocity higher. The smaller compressor wheel should also help as far as inertia drag.

For what it's worth I threw the 14 on the 3 and that woke it up. :) Now all I need is some engine management. :giggle: