"Best" LT1 year for Z swap? 383 Displacement LT1?

[Guest qwikrex]

I've seen some debate regarding this on these boards.

 

The opinion *seems* to be that the > 96' LT1's are better, cause they are ODBI, right?

 

Other than the difficulty of wiring an ODBII ECU is there a "problem" with running ODBII? Is it still possible to externally tune the ODBII ECU?

 

I've also heard that the 95' is the least desirable year for the LT1? Any reason for this?

 

On another note, is it possible to get a 383 displacement LT1? Is it accomlished the same as with a "regular" 350 small block? I.E. put in a 400 crank?

 

Thanks in advance for your patience, I realize these question have probably been asked, and answered WAY too often, but I can't seem to find any record of them here.

 

Thanks again!

[Oltmann]

1995 is the best year because it has a sealed optispark distributor (more reliable) and OBDI.

 

If you find a good deal on a 96, it will take $200-400 extra to either swap to OBDI or buy the correct tuning software. The wiring is almost identical from OBDI-OBDII, the only difference being the extra wires for the rear O2 sensors.

[dmyntti]

I also believe 95 is the best year for the reasons mentioned above.

 

As for the 383 you can buy a crank and rods for the 383 conversion. The original 400 cranks are for two piece main seal blocks and are externally balanced so they won't work on the LT1. Check cz28.com and fbody.com for more info on the 383 kits and where to get the best prices.

[Tim240z]

Look at Scat's website for cranks and kits.

http://www.scatcrankshafts.com/

[Dan Juday]

Let me see if I can offer a little clearity on why '95 is the prefered model year.

 

Up to '94 the optispark was unvented. Moisture would condence inside it and corrode and short things out. Starting in '95 GM added a positive vent system to the optispark. A simple vacuum line with a check valve that draws clean dry air from the intake after the air cleaner through the optispark. This keeps thing nice and dry in there.

 

Starting in '96 GM went to OBDII. The advantage of OBDI is that it is simpler and easy to tune and reprogram with an inexpensive piece of sofeware called TunerCat. All you need besides the software is a cable and a PC.

 

'95 is the only year where these two aspects overlap.

[Guest Jason]

Converting OBDII to OBDI is simple. Replace the 96+ computer with a 94-95'. Then, either replace the knock sensor, or wire the proper resistor into the harness (I've heard of this on various boards). You can reprogram a auto transmission computer to manual, and vice versa, so any 94-95' computer will do. I picked mine up from a wrecked cop car for $25 around Christmas time.

 

http://carputing.tripod.com/OBDII_to_OBDI_Conversion.htm

 

-Jason

[Hitman47]

I he a 95 lt1 motor what is obd1? why is it better than 2?

[jonzer12]

OBD = Onboard Diagnostics, OBDI is just a simpler system, OBDII is very similar just a bit more complex with aditional sensors and software. Due to it's more complex nature aftermarket programming for OBDII is more expensive.

[MYRON]

Isnt the 95 and earlier a "speed density" system with a crank trigger pickup in the timing cover and the 96-97 models Mass Air Flow systems?..

 

I had this issue pop up when I blew my motor in my 97 TA... I got a "take out" from a wrecking yard that had the crank trigger sensor in the timing cover.... and my original motor did not have this sensor... The car ran, but I still ended up taking it out.....

 

 

Myron

[Tim240z]

The 93 is speed density. The only difference from 94 up is the venting of the optispark.

 

Tim

[Guest qwikrex]

Thanks for all the info guys!

 

It may not hurt my feelings to go with a 96+, cause there are a few things about ODBII that I like. Including a hardware/software package that gives realtime feedback about your motor, that only works with ODBII. Anyway, computer geekyness aside, THANK YOU again.

 

[Tim240z]

Depends if you have the $$$ for the tuning software!!! That being the case, then absolutely!!!

[Guest qwikrex]

Well, just how much "more expensive" are we talking about here?

 

A couple hundred dollars difference, or a couple THOUSAND dollars difference?

 

If it's just a couple hundred different, no biggie.

 

And since we're on the topic, who makes tuning software? I've seen tunercat, and it seems, I dunno, rudimentary.

 

I come from the Acura/Honda camp where you can have an ECU modified so that you plug a serial cable into it from your laptop, and are able to watch/tune stuff while the car is running. Is this a possibility with an LT1?

 

I've seen some *basic* stuff for LT1Edit, but I can't seem to really determine *exactly* what it does.

 

Thanks again!

[Tim240z]

I use Tuner Cat on my 94 LT1. It's awesome!!!

[Guest qwikrex]

I dunno, I guess I may be confused about the TunerCat. I've done several web searches, and come up short on any info on it.

 

I *thought* that was like one of those hand held devices that asks you various questions about your setup, and tunes the way it *thinks* it should be. Is this the case?

 

Or is it a software package you run on a laptop, connected to your ECU, where you can tune fuel and timing curves etc?

 

I may just be mistaken, in fact, I'd prefer if I was.

 

Could you clear the air?

[Guest qwikrex]

Ugghh.. Ignore everything I just said, I just found a tunercat web site.

 

Reading up now. Looks like what I want.

 

.... Please standby.

[Guest qwikrex]

Yeah! Tuner cat! hehe.

 

That's exactly what I'm after. Looks like I'll need to stick with ODBI to use it though.

 

Thanks again for the feedback, and letting me eat my words in peace.

[Tim240z]

Yup, here's what you need:

Download the application from TunerCat's site.

PAy the license fee and get a serial number

Buy the correct definition file for the LT1 ($EE)-$20

Drop that file into the TunerCat directory on you computer

Buy the cable from Andrew at http://www.akmcables.com/

 

Now you are ready to read, edit and flash your PCM. IT's actually lots of fun. I still get the giggles like a little school girl evertime I do it.

 

Also download FreeScan. It's a great little program and is free to download and use. It has a dashboard screen that you can watch while the engine is running and see all the parameters that the PCM uses (Revs, inlet air temp, H2O temp, oil pressure etc etc...it's great) and you can see what trouble codes the PCM is throwing and reset them, which TunerCat cannot do.

http://www.andywhittaker.com/ecu/ecu_software.htm

 

Tim