93 engine into a 91 ZR-1

[mrycar]

My father had a little mishap with his ZR-1 caused by sudden reduction of speed and an dramatic increase in RPM when a gearshift went down instead of up. (he was not driving another relative was).

End result was a loud knocking sound from the engine. So he is purchasing the 93 LT5 crate engine that is for sale, here to put in his car.

What components does he need to purchase to make a successful swap into his 1991? Only an ECM and a prom or are there other missing components that need to be purchased?

Looks like after the succesful transplant, I'll have a spare LT5 to play with. I purchased a kit from Kurt White (his old 368 kit) and need sleeves to convert my Dad's old engine. Any leads on where I can find them?

Thanks,

Mike Shaffer
1991 ZR-1 "the Wet Vette"
Almont, Mi

[Kevin]

this is exactly why I don't let other people drive my car

[ZR1 MK]

Talk to Mike at www.acsvette.com for the sleeves and many of your machine shop needs.

[Pete]

Mike,i've put a 91 LT5 into a 94 ZR1 with no issues,you're basicly doing the opposite.
From what i can remember.
You can run the stock ECM you will have to block off the EGR on the 93 motor and extend the low oil level sensor wires since the 91's have it on the left side (driver side)of the pan and the 93-95 LT5's have them on the right side (passenger side).
Also use the 91 vacuum hoses since the newer motors have the differantial MAP under the plenum where as the 91's have them under the ECM
All the rest is the same.

Good Luck
Pete

[mrycar]

Pete, thanks for the info.

The Engine that my Dad is purchasing from ZRchris has a wiring harness and I have access to newer LT5 ECM's, looking at the wiring diagrams, it looks like most of the remaining stock wiring from 1991 will work with the 1993 ECM.

So will get a new ECM and prom for a 1993, and attach it to the 1993 engine on the 1991 ZR-1.

If that doesn't work, then will go with the option you proposed.

Mike
1991 "wet Vette" ZR-1
1991 ZR-1 (dad's)

[LTLive]

If you're going to do the swap there may be a few polution sensors that are not the same, plus the harness plugs may be different.

Sounds like there were other problems with the engine. A 5-2 or a 4-1 mis-shift shouldn't have damaged the engine. LT5's a pretty bullet proof. I know I have missed a few shifts in autocrosses and have been able to recover with no problems.

Aren't you the on who blew his plenum through his new paint job with wet NOS? I think we know who the driver was.:dancing

[mrycar]

Wasn't me this time. Was another relative, am over 350 miles away from my Dad's Zr-1.

Yup did definitely blow my intake through my hood by running lean with the nitrous. Didn't follow through and calibrate it rich enough at 176mph.

Fortunately all that was damaged on my engine was my intake and hood. The "wet Vette" runs fine now.

From what I gathered from my Dad on his ZR-1 was that the engine was low on oil, and a relative was playing with it hard. When my Dad went to use it, it sounded like a time bomb.

The new engine he purchased from Zrchris is a crate engine with all sensors except an ECM. Any changes to the ECM inputs from the Stock car, I hope to upgrade to respective 93 ZR-1 components.

I have participated in a 91 engine in a 93 body. That solution (Doug Johnson's Beast) had a 90 ecm driving the vehicle. The inverse should be true.

THANKS for the info.

Keep having fun driving.

Mike
almont, mi

[Jeffvette]

Sounds like a lifter ate it, they do not like low oil levels.

[LTLive]

Yea, oil levels are important to engines. Especially how much you need in an LT5. You should have your dad check the oil level in his cars before he drives them. An LT5 is meant to be driven not babied.

Good luck on the transplant, keep us posted with updates.

[petefias]

Wasn't me this time. Was another relative, am over 350 miles away from my Dad's Zr-1.

From what I gathered from my Dad on his ZR-1 was that the engine was low on oil, and a relative was playing with it hard. When my Dad went to use it, it sounded like a time bomb.

Mike
almont, mi

Mike,

surely it wasn't your brother now, was it?

He told me he was very gentle on it and never missed any shifts. Now, let's get this story straight.

Are you coming back to Carlisle this weekend?

Pete Fias '95 #442

[mrycar]

Don't know which relative it was, knowing my Dad, he could have let the one who wrecked his ATV 3 years in a row drive it. (it was a family reunion that weekend)

Heck, remember my Dad reaming me out when I didn't check the oil out, on any any piece of equipment I used of his. Even if it was a two foot drive. Don't know why he didn't check the oil.

I expect its the tappets, have a second set of tappets in the garage. Will investigate that when I tear engine down to rebuild it.

My dad called all excited with his new engine, although he see's a bunch of stuff not on the 91 engine, he was a bit nervous. Hope to put new engine in car during labour day weekend. Hope he can wrangle up a ECM, none in our inventories at work.

Thanks
Mike

[mrycar]

Have the engine out of the 91 and sitting beside the 93 engine. Noticed that the wiring harness is significantly different mating to the car. So am proceeding to remove the old wiring harness and install it on the new Engine.

[Patton]

Sweet Jesus, I was feeling nervous about taking my plenum off... Good luck and keep us posted, very interesting!

[mrycar]

Have one harness off, am cleaning it. New harness is coming off as we speak. Looking for replacement connectors for broken ones on old harness, ndon't want to butcher new harness.


I have had harnesses off many times, have a lot of experience with injection systems, and enough to count with ZR-1's . I used to wear a patch over one eye while working with a SCCA world challenge series ZR-1 runnign race team.

[mrycar]

Have the 93 engine outfitted with the 91 wiring harness. 93 Engine now has out 91 plenum and air horn. Engine is ready to slide into ZR-1

A few small differences in the harness the baro pressure sensor for determining relative Bars was under ecm on 91, is under the plenum on the 93, Low oil sensor on the passenger side of the 93, moved it from drivers side on the 91, plug type changed as well. o2 sensor plugs moved slightly from front to back.

EGR, was removed as am running 91 plenum and 91 wiring harness.

We saved the 93 harness and its now in my ever increasing inventory of LT5 parts.

The 91 wiring harness require several connector replacements, as they were in worse shape for wear. Replaced many of the plugs. Salvaged many from the harness of 97 SS Camaro, a few from my old FIRST injector system that once graced our 74 Vette.

Overall not a bad job, just time consuming.

Took a bunch of pictures. Too bad I don't have internet access at my home. (also the reason my old website y-car.com is off line).

[mrycar]

am in process of installing the engine. Anyone ever manage to install the engine with at least one exhaust on it?

[Z Factor]

am in process of installing the engine. Anyone ever manage to install the engine with at least one exhaust on it?

With care, an engine can be removed with both manifolds attached, however angle adjustments must be made several times. So what comes out can go back in. However, GREAT care must be used not to damage the windshield so take your time.

Good luck and let us know how it turns out.

:cheers:

[mrycar]

Engine in the car, part of the harness wired up to body.

We removed the bellhousing and the driver side manifold (header), the engine then slid in without effort.

I now have to head back to MI, so hopefully my father can finish the project. I expect there needs to be some prom changes to accomodate the variance between the 91 and 93 engines.

[mrycar]

Finally had time off from work to finishing installing the ZR-1 Engine.

After getting all the wiring harness hooked up and everything bolted down. The ZR-1 started on the first crank.

The car ran great without the power key on. Unfortunately for my dad, when the power key was switched on it ran like crap.

I pulled the plenum, and attached a vaccum pump to the secondary lines. Had my dad hit the power key to test the switch. Confirmed switch worked and definite vacuum leak on secondary system.

Tested drivers side vacuum actuator, good; passenger side actuator was bad.

When routing the wiring harness, I had commented to my dad that the vacuum actuator on the passenger side crate engine was rotated 180 degrees from recommended position. This was a common mistake from the factory.

Well, after sitting for 12 years this vacuum actuator had cracked rubbers.

Pulled one the actuators off of his old engine, bolted everthing together and enjoyed the sounds of a proper firing LT5.

Swap of an 93 engine into a 91 corvette is complete.

Tasks needing done for the conversion are:

Removal of EGR system, make block plate for old EGR hole on plenum
Extending Oil sensor wiring from drivers side to passenger side
removal of 91 ECM wiring harness and attaching it to 93 LT5
(safely remove 93 wiring harness for someone else.)
removal of solid state ignition module underneath plenum and replace with 91 system.
Validate secondary actuators are rotated so that the flat backside is facing the outside of the engine. (reduces stress on rubber components int he actuator) Optional things done for our system:

Replaced 93 plenum with 91 plenum
Repair 91 wiring harness, with new connectors
replace alternator due to wiring harness being galvanized to + stud on alternator
replace both actuators
use updated 93 grounding harnesses
Validate seconday actuators system opens fully by 10hg. (Ours did at 5hg) Thanks for all those that provided advice.

Mike

[Jeffvette]

Mike, don't forget changing the secondary vacuum harness. Unless you did some other modifications to it.

Also, you shouldn't have had to change the DIS module as it's one part number for 90-95. But I guess it was easier to leave it bolted on when you swapped the plenum.

[mrycar]

I modified the vacuum secondary harness.

The 93 DIS may have shared the same part number, but it was significantly different then the 91 DIS. MY Dad's plenum was powercoated red, so he wanted to maintain the old color vs the gray. So I just left the old one on.

He is all excited about getting his ZR-1 Ready. He is hoping that he now will have a ZR-1 that can pull like mine.

[Corvette95]

Did this project ever get completed? What happened to the old engine? Do you want to sell me the old engine? corvette95@gmail.com