Hello all!

Been lurking a while and finally signed up to post. Been trying to learn as much as possible, so thanks to everyone for there posts. My goal is a NA-T with hp aspirations in the 500hp-600hp range.
I'm having a problem picking which year chasis to start with. From what I've read, the non-VVTI engines are preferable because of their strength. However, most 92-96 cars I've come across are in pretty rough condition. On the other hand, most 1997+ SC300's are in better condition, but now the problem with passing emissions comes up (OBD-II). How do people pass emissions with OBD-II boosted cars? Is it possible to retain all the emission components when going NA-T?

I was thinking one work around would be to keep all the emission components and run the original ECU with a piggyback to keep all the CEL lights off. Would that work?

 

Well, depending on your particular locale.... if it's a very strict area you kind of don't unless your engine is stock.

While an NA-T is the economical way to go boosted (although 500-600hp will cost roughly the same money no matter what engine variant you use) it's not possible to pass emissions AND a visual inspection with an NA-T. Certainly not in California. I don't know what the inspection requirements are like in Texas.

Basically the older the SC chassis (OBD1) the easier it will be to pass emissions for that chassis with a turbo JZ engine. And yes you technically can keep the 2JZ-GE's EGR system working on an NA-T... at least I think Ali_SC3 has demonstrated how to do it. Assuming you're tuned conservatively enough (but you definitely don't want to run lean with a turbo) an OBD1 SC300 with an NA-T and working EGR with two OEM aftermarket replacement cats *might* pass emissions but I really can't speak from experience. It would really depend on the setup.

But if a visual inspection is required... an NA-T engine will not look stock to the technician and you would still fail for that no matter what. Same deal in CA.

To go NA-T up to around 500whp the popular inexpensive ECU to use is a JDM Aristo 2JZGTE computer. That will not have EGR function programmed into it however. It's just a very foolproof ECU setup for NA-T SC's regardless of emissions.

Now you MIGHT have better luck by swapping in a full *stock* 2JZ-GTE VVT-i or a *stock* 1JZ-GTE VVT-i into a 1996-2000 SC300 or maybe just a 1998-2000 SC300 (since those are set up for VVT-i engines stock). Gerrb's big engine harness thread goes into greater detail about how the later SC's electrically area easier to swap to JDM VVT-i engines.

Also, if you start with a 98-00 VVT-i SC300 you can pull the engine, swap the bottom end for a good 92-97 short block or build the 98-00 bottom end with stronger rods, pistons, rings and new Toyota bearings. Then you'd have the strength of a 92-97 GE block or any GTE block. The VVT-i cylinder heads actually incorporate an EGR-like function with their variable valve timing on the intake cam thus eliminating the need for traditional EGR.

I cannot speak to how anyone passes emissions anywhere with a built NA-T VVT-i setup either with the GE VVT-i or 1JZ/2JZ-GTE VVT-i heads but at the very least the variable valve system could make them run cleaner with two appropriate catalytic convertors fitted. HOW clean and to what emission standard as applies to the U.S. I can't really say.

I tend to think the emission testing programs aren't really getting any easier. It really depends on where you are located and what the local testing requirements are.

With my SC, a California car, I went with a full by-the-book USDM 2JZ-GTE swap for the Supra MKIV TT in OBD1 spec. It is outputting, at most but maybe a little less than, 350hp/350tq (both crank numbers) and uses the complicated sequential twin system. Nowhere near your desired 500-600whp numbers. Full stock EGR system, stock Toyota pistons and rings, stock Toyota catalytic convertors, stock Supra TT ECU, stock fuel system, stock vacuum hose routing... stock (for the engine) everything. It hasn't gone back to Cali for testing yet but barring any worn out emission parts I'd need to address it should pass over there, visual inspection included. It was pretty involved because I had to stick to keeping as many aspects of the build as stock as possible (for a 93-95 USDM Supra Turbo). This even included a re-cored side mount intercooler setup rather than an aftermarket front mount.

However my car will not compare to a 600whp 2JZ car having roughly half the power output using early 90's turbo technology. Doing a totally stock USDM 2JZ-GTE build/swap in a 1992-1998 SC300/400 chassis (since no Supra Turbos were sold after model year 1998 in the U.S.) is the only truly foolproof way I know how to pass smog with a turbo JZ engine swap anywhere without issue but especially in CA.

(Exceptions for California residents with a JDM 2JZGTE or 1JZGTE is to talk to Sean Morris through his JDM car importation business since he is a guru with any JDM imports. He was the engineer who made the R33 GT-R's truly and honestly legal stateside before the *owners* of that company started ruining everything with their own illegal activities and passing off R32's and R34's as being the same thing. Really old history now. He has a relationship with G&K Auto based in SoCal who, for a hefty price and a long waiting list, can re-engineer almost any vehicle's engine to pass the required emissions for its original model year. But for that we're talking some big money just to hand the car over for those modifications).

I would look carefully into what the emissions testing requirements are in your area of Texas for both OBD1 and OBD2 cars. And I do think there may be a better chance if you plan on keeping two cats on the vehicle as well as a working EGR system or a GE/GTE VVT-i head which should achieve much of the same effect as old fashioned hardware based EGR that non-VVT-i USDM/UK/Euro 2JZ engines used.

 

THANK YOU SO MUCH FOR THE REPLY!

I think I 'm going to stick with a 92-95 model for the sake of simplicity. Here in Texas, after 25 years, all cars only get a safety exam, no emissions no OBD testing. Maybe as the years roll by, I can upgrade to a 97+. lol

 

If you even have to type out the word emissions you are safer starting with a 92-95 for lots of reasons.
If you have to do an obd2 plug in you will have to setup lots of things perfectly and be in a sort of maybe situation.

I thought most of texas was just a safety inspection from when I lived there, but its been a long time.
You can probably find a relatively clean chassis (no wrecks w/decent mileage) with the usual SC cosmetic issues and spend time getting it back in shape vs messing with obd2.
with obd2 you will also have to source a non vvti bottom end if you plan to boost it much, and taking apart 2 engines and making one takes alot more time than isntalling a body kit and swapping interior pieces.
Just my .02 been there lol

 

^^ I'm agreed with Ali on this! While there are great options for VVT-i GTE or GE VVT-i NA-T with late model SC's, for your purposes it will be the easiest with a 92-95 OBD1 chassis.

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Aside (and a visual inspection portion of a smog test notwithstanding), Ali I'm actually curious about this myself:

Can you speak a little bit about how you kept your SC300's 2JZ-GE EGR working when you went NA-T? And also what ECU you were using at the time you did it? I figured the Aristo 2JZGTE ECU (if that's what you were using) wouldn't have been able to control the USDM 2JZ-GE's EGR VSV.

Having working two cats installed is as easy as welding up whatever Magnaflow or Catco cats are available rated for Supra MKIV TT's and hooking up or welding in bungs for whichever oxygen sensors the ECU system needs. But to the best of my knowledge the 80's/90's Toyota EGR systems don't work efficiently unless there is EGR VSV control from the main ECU.

Like you don't want too much EGR gas from the EGR valve's diaphragm under idle conditions or the engine will stall out. It's more a part throttle or lift-off throttle emission control sub-system... right?

Or is there some other non-VSV ("Vacuum Switching Valve" solenoid for people first learning these terms) based way, with an NA-T setup, to get the EGR's vacuum modulator to work at the correct times to in turn operate the EGR valve's diaphragm only when it's needed?

 

The JDM ecu doesn't control the egr properly (via the egr vsv and vacuum lines) and it can cause different issues with the exhaust bypassing the turbo at the wrong times (egt codes, loose spool etc..).
Without using a standalone programmed to control EGR (which could be done, or maybe its possible to do it mechanically not sure) the easiest option is to remove it.
If one doesn't want to get involved with removing everything and rerouting vacuum lines etc... one could leave it in place and disable it, however, it would not actually work if it were to be tested.

That being said, even JDM engines without EGR have been known to be well within the limits when using the good catalytic converters.

The generic high flow cat's might not be good enough though, but if you get the more expensive high flow cats that are "oem style" they are much better.

Like on my audi I installed 2x 3" high flow magnaflow cats and they did not get the numbers down, and this is on a regular audi engine (w/custom downpipes due to the swap)
When I got the more expensive high flow magnaflow that was OEM style (has a lot more material inside), just one of them brought the numbers down a surprising amount.
So I no longer buy the generic high flow cats, even if they work they wont last a long time and you will be replacing them every few years.