Regarding my 1989 IROC Z Vert (autotrans) , I'm thinking about swapping the 305 TPI to a 350 L31

.Anyone know of L31 R 350 swaps, that maintained all OE smog equipment, running clean enough to pass SMOG? I realize standards vary, from state to state, w/ cali (here) being the toughest. Thanks.

 

I would talk to a referee station in CA before doing any swap.

As I understand it (I don't live in CA)
The smog equipment must be better than the stock car and you must maintain all smog equipment as installed from the donor car.
There are also restrictions on placement of the cats. I don't know CA law here but they have to be within a certain distance of the original placement.
CA doesn't usually certify truck to car swaps so if the L31 comes out of a truck and the PCM has the truck VIN it may be an issue (question for the referee)

Then you have to take it to a referee station and have it inspected, but they will not pass it until you have driven it far enough so that the ECU/PCM has completed all internal tests. CA has moving wavers you can get that will allow you to drive it for a day, this would be enough to drive it to get the car to the point where all the tests pass (assuming the do).

My LS1/T56 swap should pass a CA inspection, I have all the smog equipment that matches the VIN in the ECU. And I have factory (GM) cats. They are the exact distance from the the engine as installed in the 2000, only difference is I had to re-clock them (rotate them) so they would clear the frame rail.

 

I am looking for accounts of vehicles that have passed or failed the "sniff test' . IE First hand accounts of how clean a L31r runs with all the 305 smog equipment hooked up and running. Thank you.

 

Ahh that depends alot on the intake.

The L31 is a vortec engine and will not accept your factory intake straight with the vortec heads will it? If not it would negate your stock EGR system.

What is your plan on the intake?

 

I would use a "Vortec" style lower intake, possibly from a C4 Corvette 350(w/ EGR Provisions) or maybe this

http://www.superchevy.com/how-to/eng...-tpi-manifold/

 

Interesting intake, to know for sure you would need to test the exact setup. But with the right tune in the ECU I would guess as clean or cleaner. Ask the company what the sniff test numbers are.

Doesn't CA do a visual inspection to verify correct engine and requires all aftermarket parts to be CARB approved?

 

https://bar.ca.gov/pdf/Smog_Check_Reference_Guide.pdf

This is where CA would be an issue: -- you could probably run the 305 block with vortec heads and that intake and get through inspection but the full engine out of a truck would never pass in CA unless you get lucky and sneak it through.

"All model year vehicles (gasoline, diesel, hybrid, CNG, LNG, LPG, etc.) must meet the following:1.Model Year -The installed engine must be of the same model year or newer than the model year of the recipient vehicle2.Engine Classification -Vehicle and engine classifications of the donor and recipient vehicles must be the same basedonGrossVehicle Weight Rating (GVWR). Classification examples include passenger car, light-duty truck (LDT1, LDT2), light-heavy-duty truck (LHD1, LHD2), medium-duty vehicle (MDV), etc. For example,aheavy-duty truck engine may not be installed in a light-duty truck even if they have the same displacement. Non-emissions controlled engines, such as industrial and off-road-use-only engines, and non-certified “crate engines”, MAY NOTbe installedin any emission-controlled vehicle"

As well as:

"OBD-II System -Any vehicle with a replacement engine from a donor vehicle that was originally equipped with an OBD-II system must support all OBD-II functionality from the donor vehicle:"

 

If I go w/ a Corvette Vortec lower intake, it's a GM numbered OE part. ("Close Enough for govt." ) The Scoggin Dickey Vortec has a GM part number on it and looks like stock. ALL OTHER SMOG EQUIPMENT will be in place, tested and operating properly.

 

You can't use a Corvette TPI intake. None of them. Won't bolt to the heads on the L31. No Vette ever came with TPI and any intake that will bolt to L31 heads. Not C4, C3, C0, C15. NONE. Doesn't exist.



There is exactly ONE base in all the world that will work for this application. Originally, Scoggin-Dickey Chevrolet had it made for them. I think nowadays the only source for it is Edelbrock (same part, different distribution channel) but don't take my word for that, do the research. Hint: check the date on that SuperChevy article you posted, before just "a$$-u-me"ing you're going to buy it. (also note the brand name just below the intake manifold in the photo... pretty sure that's an actual TPI base)

It was possible at one time to use that intake, and the EGR pipe from about a 88-up L98 Vette, which went from an exhaust manifold port to a valve mounted on the intake; and some EGR valve, I don't know what one. Might even have been a "kit" including all this available at one time. Maybe still. But maybe not anymore. Iunno. Sounds GREAT though: all ya gotta do now, is track down all those pieces, and find an exhaust manifold that has that port. An exhaust MANIFOLD, not headers. Only ones that had it, were L98 Vettes. Good luck. The usual method of obtaining exhaust gases for the EGR system, which is ports in the center of the head that hook up to the intake at the flange, doesn't exist on the Vette aluminum heads, or the L31 heads; making this workaround the only available option. I have no idea whether all/any of the parts needed to make this happen are still available. DO THE RESEARCH before you spend the first dime.

Frankly, in CA, I would advise STRONGLY against this swap. It's just too much of a can of worms.

I appreciate Aviator's thoughtfulness, but he obviously has never lived in CA, and doesn't know what they do and look at out there. It's the HEADS that are the problem, not the block. I lived in Carlsbad, and became more familiar than I cared to with the rules, and their enforcement. I also drove around in LA about this time of the year once in awhile (I hate LA, I avoided it like the plague and still do, because it was/is … the plague)... when the air was SO THICKLY BROWN you couldn't see the signs above the freeway telling you which exit you were at. It gets WAAAAAAAAAYYYYYY worse than SF was last fall during the fires. (Yes, I was there acoupla times while that was going on) People in the rest of the country love to bash "commiefornia" and the like, but until you've tried to breathe the … stuff … that auto exhaust is responsible for in that place, you AREN'T qualified to have an opinion on their laws. China has a similar problem, for some of the same reasons, except there, it's even worse because they also use so much coal.



You can use a L31 SHORT BLOCK and no one will ever know the difference. It looks just like any other small block Chevy block, they don't check casting numbers on blocks unless they get suspicious (too much like work), that's one thing they'll NEVER notice. Then get some good aftermarket heads with the EGR provision in the intake flange. Don't go too hog-wild on this, TPI will ASSURE that there is an absolute hard upper limit to any improvements you can make. Paint em black to match the rest of the engine as closely as possible: make em hide. As long as that thing is on top, nothing underneath it matters performance-wise, past a certain point. If memory serves, the Edelbrock Performer (not RPM) heads are CARB certified for this situation. If this is still true, that's probably the best/cheapest alternative you have. Have the CARB EO # with you in case the inspector notices the heads. The Vortec HEADS - the NICE thing about the L31 - are EXTREMELY hard to get through smog. I would STRONGLY advise against trying to put those under TPI unless you are willing to (a) spend LOTS of $$$; (b) make LOTS of trips to the inspection station; (c) achieve minimal performance gains from this, the only thing you'll get being bragging rights "yeah it's got Vortec heads on it" after some Kia minivan hands you your butt; and/or (d) have a backup plan ANYWAY in case it doesn't work, wherein you are totally prepared, without any hesitation reservation or equivocation, to throw everything you've put (a) and (b) into and been willing to accept (c), into the TRASH, and start over FROM SCRATCH.

CA inspection stations are one of those classic "bring me a rock" deals. You know... boss says, "Bring me a rock". You think, no problem, there's rocks all over around here, how hard can this possibly be. You pick one up and bring it to him/her. "I was thinking of a bigger one". You get a big one. "That one is too dark". You go find a nearly white big one. "I wanted one that wasn't so pointy, more smooth". You go get a large nearly white river boulder. "That's too heavy". … No doubt you've had a boss like that. Well, CA inspection is like that, once you fail. It's VERY frustrating to try to get from Fail to Pass, once you've already landed on Fail. Avoid it.

 

The lack of EGR in the Vortec heads, makes my intended swap, impractical. LORD cali hates old car!

Thank you all for the information.

 

The good news is you could always use a roller 350 and bolt on a set of aftermarket heads like the Dart 180cc heads that have an exhaust crossover passageway and nobody would be the wiser. You could use a factory 85-86 TPI base at that point.

 

If CA truly wanted to make the air cleaner they would let you easily replace your old worn out engine with something like a 4.8 or 5.3 truck engine.

 

Yes, that's pretty much the reason why you can't use Vortec heads on a TBI setup. You could get away with using them if you converted to TPI, because the TPI Corvettes use an external style EGR setup. We've passed with that here in SoCal.
Otherwise you can build a mild 350 TBI and enjoy it without telling the smog guy, because as sofaking said they look the same on the outside and nobody has to know.

Yes you *can* swap to an LS-based engine, but it has to be one from a car, not a truck, and you have to swap EVERYTHING emissions related from the donor car to your car. That's the pain in the *** as GM put the emissions devices on the newer cars in places that will not physically fit in a thirdgen chassis.

 

Kevin. My IROC IS TPI, not TBI.

 

The external EGR, with the pipe running from the exh manifold to the int one, is specific to TPI Vettes. While it "exists" in the historic sense, and Kevin and accomplices used to do that sort of thing back in the day, parts availability IN 2019 may pose a major hurdle. It's just … obsolete. A simple matter of lack of demand vs willingness to supply. I'd be willing to bet though (I haven't talked to Kevin for quite awhile) that it's been several turnings of the moon since he last went to the stealership and actually bought that "kit", or even, all the individual pieces in it.

TBI AFAIK offers no such upgrade path at all, which is why Kevin mentioned it.

While not impossible, a Vortec TPI is also not a slam-dunk. DO YOUR RESEARCH; locate the parts PHYSICALLY, not just on a web site or in a catalog; buy what you can when it passes by in front of you; and be prepared, psychologically and financially, to THROW IT IN THE TRASH when some critical sine qua non part cannot be sourced. And be aware UP FRONT that nearly everyone that's done it has been disappointed... TPI prevents the advantages of Vortec heads from ever revealing themselves fully. It produces NOWHERE NEAR the power of a simple carbed setup. Which is not legally accessible to you in any case.

A LSx swap from a car (as said, you can't use truck stuff) is relatively simple and easy to get through smog. "Relatively" being the operative concept here. A GTO or 2010-up Camaro pullout or some such will STOMP a TPI motor with ANY heads into the dirt, and get MUCH better gas mileage to boot. Which is easy to overlook, in a way; but gas mileage pays you back every day for the cost of the swap. Don't overlook that benefit (or disadvantage) in your calculations. As well as, putting in 10-yr-old electrical wiring and whatnot that's just BETTER to begin with, compared to re-using your 30-odd-yr-old wore-out 80s stuff that's turning to dust right in front of your eyes already. What seems cheeeeep or eeeeeezy today may well drain your pocketbook on a daily basis FOR YEARS afterwards.

 

Am I just concocting things from the garbage heaps of crazy factoids bouncing around my head, or is the EGR port on the Corvette style intake a direct match to an oil drain on a T3 turbocharger? Seem to remember that from somewhere.

No matter, pretty sure the flex tube from a 3.1L that runs from the digital EGR to the plenum will bolt up too... Then its just a matter of getting a flange made and welding it onto the header,


But you know, eff that... Just get out of Commiefornia. Prop 65 tells you that everything under the sun will give you the cancer and make your ****** shrivel up and fall off... Just geet while the geetin is good.

 

My apologies, I misread your first post.


Ahem, my setup, my dad's setup, both ~400 hp to the wheels, beg to differ otherwise.

My dad also has an '87 El Camino with vortec heads, TPI intake, and stock LT1 cam. It passed the emissions test just fine after going to the referee first to ok the swap. (thankfully he didnt notice the vortec "truck" heads, but he was ok with the external Corvette-style EGR).