What are the differences between a JSPEC JDM engine and a stock NA 90 T2. A car I bought had a jdm engine and I'm wondering for ease of maintenance if I should go back to stock NA. What are the differences between the engines and the components on the engine. If there is a FAQ on this topic, could someone direct me to it?

 

whats a "stock NA 90 T2"

 

I guess in this context NA = North American......

This is all off memory, I could be a little off.

NA-spec T2 = 200 hp
J-Spec = 202 hp
J-Spec Infini III = 212 hp + 4.3 Final Drive Rear End with Torsen LSD. Me want!

 

N/A mainly means non turbo!

 

in this context, NA could refer to North American

N/A does not universally stand for Naturally Aspirated.....

let's see, there's North America, Not Available.....you see where I'm going with this.

 

Okay, lets see if I can clear this up. I have a 1990 T2 JDM engine installed in my 1990 Mazda RX-7 T2. I need to replace it. I'm wondering if I should replace it with another JDM engine, or a normal United States 1990-1991 Turbo 2. What will sway my decision is comapatability of parts. Sya I need a water pump and wonder down to the ole parts gettin' place and say give me one. My question is will there be problem getting parts like water pump, clutch, spark plugs etc.. Or can I use normal 1990-1991 T2 parts.

 

Everythign inside and out are the same except for the following:

-wiring harness...obviously if the jspec is in your car you are using a US harness
-no AWS valve or hoses on jspec
-I am almost certain jspec has no ASV valve or hoses
-jspec has smaller smog pump and different bracketry for it
-jspec has no fan thermoswitch for the aux e-fan in front of t2 and AT models
-jspec throttlebody has a phillips screw for idle adjustment, US has a flat setscrew with an 8mm locknut
-jspec BAC valve does not have an idle air bypass adjustment for idle fine tuning
-jspec LIM has the brake booster vacuum outlet on it, US UIM has the brake booster outlet on it

Essentially they are the same thing. There is no performance or parts availability difference between them.

 

Any one got a pic of the jspec uim and lim? Im curios about how some of the stuff is routed and/or pluged.

example: no AWS valve. so where does that hose go? Is the port for the split air blocked off? Welded shut? What about the ACV how does it function on the Jspec? Just wondering about how well the intakes would work for emmisins removal..

 

J-spec engines have both of these things.

It's mostly the same. No exciting differences.

There's no hose.

The split air pipe is still there.

It functions basically the same, but the relief air discharge point is in a different location and the split air solenoid valve is not there.

Most of the emissions equipment is the same. The only emissions-related differences are the lack of EGR on S4's and the lack of AWS nipple.

 

I'd have to disagree. I've worked with many jspec manifolds/engines over the years as you might imagine, and in fact I have an s5 jspec that just came in today. It has neither the ASV nor the fan thermoswitch. Both areas are left blank, not drilled at all.

 

 

Well you said they don't have either, but mine has both. Maybe some don't, but that's not what you said.

 

Thank you.

 

I would guess that whats been sent to and is available in NZ is a bit different than what we got in the US

 

Jspecs have had some weird stuff on them. They seem to differ between cars more than US ones do.

Mine is missing a few thins as well. I kind of prefer them over US manifolds.
Less things to remove/block off.

I also like the placement of the brake booster vacuum port. On the LIM versus the pain in the *** to get to bottom of UIM section

 

Perhaps it is an s4 vs s5 thing. I have only seen 1 s4 jspec, and probably 10+ s5 jspec setups. The s5 jspecs seem consistent in that they have no AWS, ASV, or fan thermoswitch.

 

Nearly all FC's in NZ are used Japanese imports, which is what this treads about (i.e. J-spec engines).