getBAK

Hello all - I am looking at building a replacement engine for my 2002 Z06 Corvette.
I'd like to do an LS3 swap, but have some issues.
In short I need the engine to be able to run on a OEM ECM tune for brief periods of time. I'd like to be able to remove the LS3 intake manifold with the injectors and throttle body as a single assembly, swap on the factory LS6 Intake/TB/Injectors as a single assembly, reflash the ECM to stock and be good to go. Seems like this could be executed in a couple of hours

Obviously the LS3 runs Rec-Port heads, different fuel injectors, throttle body etc.
I'm considering a build where I use the LS6 intake manifold with a Cath-to-Rec port adaptor ( https://www.ictbillet.com/ls-rectangle-port-cylinder-head-to-cathedral-intake-adapters.html ). In general adaptors make my skin crawl, I know this isn't an everyday system. I need it to be able to work for a couple hours at a time.

Could this work?

grinder11

iTrader: (1)

Are you trying to circumvent a smog check rule? IDK why else you'd go to this trouble. I'm pretty sure you could make up two tunes, like one for regular gas, one for premium. Except one tune would be the LS6 tune, and one would be for the LS3, instead of regular and premium fuel. Probably have to store both tunes in a handheld device like a Diablsport. I'm not a tune guy, but know enough to get myself-and you-in trouble, lol. Hopefully some tune guys will chime in. I'm sure a good tuner could make both tunes up and store them in a laptop using HP Tuners. I'm not that guy, however. IMHO, I think what you are wanting to do is possible, though. Hope this helps..

LS1 TJ

Just throwing this out there.
How about iron block 5.3 bored and stroked to 383 cubes? Some good heads that use the the LS6 intake? Then you could use all the 02 C5 wiring, ECM and other stuff?
I know it add some weight to the nose but I bet you would not even notice.

getBAK

I'll never tell....


Hard no on that. 200 lbs on the nose of the car matters.
Part of what's going on here: I can buy a GM LS3 Crate motor, brand new including everything for $<10K it includes the rec-port heads, which pretty much kick any Cath port head's ***.
If I want to build an LS3/Cathedral port hybrid - or an Aluminum Gen III - it's going to cost ~$13K all said and done.

wannafbody

iTrader: (2)

I'm not sure how someone would visually know the difference between a LS6 top end and a LS3 top end by looking unless they know LS engines really well. Factory intakes all look pretty similar.

getBAK

It's less visual and more to do with the ECM programming
The LS3 and LS1 use different fuel injectors and a different throttle body. The ECM programming is very different.
If the ECM is programming is altered the car automatically fails certain tests

gametech

iTrader: (1)

Your idea is an absolute non-starter. The ls3 will definitely NOT work on your factory ls1 pcm. Technically you could piggyback a Lingenfelter crank trigger adapter box on to make it work, but that is just one of the problems. There are so many problems with this idea that a book could be written explaining them.

Old Buzzard

" which pretty much kick any Cath port head's ***".

grinder11

iTrader: (1)

If the motor is on a stand, or out of the car, you could swap a 24x reluctor wheel for the 58x. But I agree, and posted that I can't see this as being too feasible. Could it be done? Probably. But we could probably build a bridge across a dry lake bed in the Mojave desert, too. Then sit back and wait for the water to come!! Neither plan is really good. Big difference between could be, and should be!!

getBAK

Please explain to me why this is such a problem. Let's assume I'm using a 24/58 reluctor adaptor already.
I'm aware with the LS3 swap that some sensors move around, but they are the same sensors (outlined here ). It appears that once you deal with the ECM tuning and a few wiring harness, the LS3 swap itself is pretty straightforward (well as much any any engine swap can be).
To be clear, this isn't going to have a massive cam in it - this is basically a stock C6 430HP 6.2.
So - if we go back to the factory tune - take the adaptor harness off the fuel injectors/ throttle body, and go back to the factory 'manifold package'. Where does this go wrong?
Not trying to fight here, just want to understand.

V1_hitbox

What year and kind of car?

getBAK

2002 Corvette Z06

V1_hitbox

your best bet would be a 6.2 block, ls6 top end. Honestly, you’d get more out of stroking your ls6 for less.

the_merv

iTrader: (88)

^^That right there, buddy of mine did it with a 24X Crank and it rocked. 243 Heads & LS6 Intake on it, kept the red FRC's and everything, looked sharp and the car was stout. Had a little Cam in it too.

Not sure what the guy posting this whole thread is trying to accomplish but seems way over complicated, like waaayyyy over complicated...

I could tell instantly, there's quite a few differences. One dead giveaway is the Fuel Rails, LS6 are black LS3 are silver. LS6 Intake has the plastic diamond in the front of it behind the Throttle Body, LS3 is smooth with the MAP Sensor right behind the Throttle Body screwed in on the passenger side. Take me half a second to identify that one. Then again built enough of them.
Take me a nother whole second to look at the number on the front passenger corner of the Cyl Head..

getBAK

Ok - I'll explain:
CA Smog connects to the OBD port and checks the CVN/CSV of the ECM. If that is not stock, the car fails... period. The Smog tech has no say in the matter, transmission comes directly from the state.
If you run LS3 injectors and throttle body, you have to tune the ECM for them.
If you can swap the entire manifold TB and injectors in 1 piece, you can load the factory tune and be smog ready in a couple hours of labor

AgFormula02

iTrader: (13)

Ok, so tune has to be kept stock.
do they do any type of run testing?
(like the old dyno test at 3500 rpm?)

I think the idea should work, in theory at least.

Just seems like a lot of work.

Can you register your car in Nevada?

getBAK

No, out of state registration is not practical. California DMV has a whole task force set up to bust people. Technically anything that’s inside the state for more than 90 days needs to be registered.

dixiebandit69

What if you try some other way of faking out the sniffer? The OBD port can't tell you which injectors you have; they all ohm-out the same. If the throttle body is wired correctly, it doesn't know.

You can "fake" the emissions test results with additives in the fuel tank.

Luckily, I don't live in a state that does emissions checks, but they do check window tint. So whenever I have to take my car in for an inspection, I roll all the windows down... Then I pull the window fuse.

But yeah, an adapter for the intake sounds dumb. There are easier ways.

the_merv

iTrader: (88)

Moving out of commiefornia would be a start..

getBAK

you're trying to make this logical. CA doesn't actually have a sniffer test anymore. They check for components, ,readiness, codes and ECM tune. I guess they figure that if anything is off it will throw a code and thus fail.
The CVN is the sum of all of the lines of code in the ECM, if you have different fuel injectors tuned, they show up in the code. Gen III and Gen IV injectors are different. The LS1/6 use the tall injector.