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First off I would like to give a huge thank you to those with intelligent posts insights and responses, they have been invaluable through the course of my build. I know there have been a number of attempts at this chronicled on TGO but this is the story of a completed LT5 IROC build.
I purchased my 1989 IROC vert in 2014 it had been sitting on the side of the road for 6 years and still rust free which was amazing. After having it trucked home we got it running but the 5.0L TPI engine and trans were shot and it did not run very long and leaked like a sieve. As these things tend to snowball, I found a wrecked 1989 IROC with 5.7L TPI with same dove grey interior. I installed the 5.7L engine and trans along with the 9 bolt Borg Warner rear end with discs and PBR calipers. After swapping the engine, trans, 3” exhaust and rear end along with a complete suspension rebuild including all bushings my vert was on the road again. I then picked up off CL a set of 1LE front spindles with brakes and along with new braided SS brake lines and the car was again on the road and but it was not for long before the 2nd trans went out. At this point we located a T-56 from a 97 Camaro SS and the vert was back on the road and a lot more fun to drive. In 2018 after spending 4 months doing body work, swapping a door, a fender, rear bumper cover and the hood my IROC vert was finally painted in a Lexus tri-coat white color. At this time the Hawks 17” IROC 2 vein wheels were installed and we upgraded the rear gears to 3.73 with a stud girdle cover. So finally after 4 years of numerous upgrades, starts and stops my vert was on the road looking great and fun to drive. So the summer of 2018 and 2019 I put some miles on it attended a few car shows here in the PNW. Then in 2019 the upgrade bug hit me once again when I saw a 1990 ZR1 LT5 engine for sale with only 17K miles on it. I gotta tell you this is one of my favorite engines of all time and I had to have it. After a cross state road trip I had a LT5 sitting in my garage and was ready to tear my vert down again. After almost 2 years my vert is on the road again. Installing a LT5 in a 3rd gen takes some ingenuity and creativity. Originally I was going to use all of the stock sensors, ECM, waste fire coils, engine wiring harness etc. After some deliberation we decided to treat it like an LS engine and installed 8 LS coiIs with custom mounting system under the pleneum, removed the vacuum controlled secondary butterflies, ported the intake housing and plenum, deleted the throttle body coolant, built a custom wiring harness, modified the existing 1997 LT1 bell housing and drilling tapping 1 new bolt hole in the block. Machined a custom billet fuel block for the existing fuel rails.
I used the following major components in this build;
UMI K-member (modified)and control arms
Dirty Dingo adjustable LS engine mounts
MegaSquirt MS3 EVOPro ECM with a flying harness
OBX SS ZR1 headers, JetHot coated modified for the 3rd gen cross member
Holley 2.5” true dual SS header back exhaust system
Custom crank trigger based off the Holley kit
Custom dual 3” intake
4th Gen fuel tank with a Aeromotive 340 LPH pump
New 3/8” SS fuel lines from the tank to engine compartment
BMR remote mount battery tray
Fidanza flywheel
Per Marc Haibeck, based on the engine mods I have done this should be putting out 450+ HP at the crank based on his experience with these changes. On my first outing I can tell you this thing is crazy fast with a 7,500 RPM redline compared to the old TPI engine
For those of you not familiar with the engine or need a refresher as there are many incorrect posts about this engine please see the link below;
Cost wise this came out very close to a high end LS swap and parts are plentiful you just need to know where to look.
A big shout out to my son Cody who was with me all the way, my very good friend Soloc4, Bruce and his crew at Hawks, Mario from the Dub Shop for MegaSquirt tuning, Jerry’s gaskets, and Marc Haibeck ZR1 expert extraodinaar.
I remember the first time a Chevy rep brought one of these (ZR1) around for us to see...balanced a nickel on edge on the running engine. I thought it was one of the cooler things I had seen in my (then) young life.
Congrats on a very cool build!
Last edited by DynoDave43; 01-03-2022 at 09:09 PM.
OMG! My Holy Grail! That's the only engine I'd swap the for our generational TPI. I've had my eye on one, but it'll take a lot of stimulus checks for that to become a reality lol. Beautiful car, too, btw.
When I saw the title of this thread, I expected to see the new LT5. So when I saw this one, I, well, it was like looking at ****!
First off I would like to give a huge thank you to those with intelligent posts insights and responses, they have been invaluable through the course of my build. I know there have been a number of attempts at this chronicled on TGO but this is the story of a completed LT5 IROC build.
I purchased my 1989 IROC vert in 2014 it had been sitting on the side of the road for 6 years and still rust free which was amazing. After having it trucked home we got it running but the 5.0L TPI engine and trans were shot and it did not run very long and leaked like a sieve. As these things tend to snowball, I found a wrecked 1989 IROC with 5.7L TPI with same dove grey interior. I installed the 5.7L engine and trans along with the 9 bolt Borg Warner rear end with discs and PBR calipers. After swapping the engine, trans, 3” exhaust and rear end along with a complete suspension rebuild including all bushings my vert was on the road again. I then picked up off CL a set of 1LE front spindles with brakes and along with new braided SS brake lines and the car was again on the road and but it was not for long before the 2nd trans went out. At this point we located a T-56 from a 97 Camaro SS and the vert was back on the road and a lot more fun to drive. In 2018 after spending 4 months doing body work, swapping a door, a fender, rear bumper cover and the hood my IROC vert was finally painted in a Lexus tri-coat white color. At this time the Hawks 17” IROC 2 vein wheels were installed and we upgraded the rear gears to 3.73 with a stud girdle cover. So finally after 4 years of numerous upgrades, starts and stops my vert was on the road looking great and fun to drive. So the summer of 2018 and 2019 I put some miles on it attended a few car shows here in the PNW. Then in 2019 the upgrade bug hit me once again when I saw a 1990 ZR1 LT5 engine for sale with only 17K miles on it. I gotta tell you this is one of my favorite engines of all time and I had to have it. After a cross state road trip I had a LT5 sitting in my garage and was ready to tear my vert down again. After almost 2 years my vert is on the road again. Installing a LT5 in a 3rd gen takes some ingenuity and creativity. Originally I was going to use all of the stock sensors, ECM, waste fire coils, engine wiring harness etc. After some deliberation we decided to treat it like an LS engine and installed 8 LS coiIs with custom mounting system under the pleneum, removed the vacuum controlled secondary butterflies, ported the intake housing and plenum, deleted the throttle body coolant, built a custom wiring harness, modified the existing 1997 LT1 bell housing and drilling tapping 1 new bolt hole in the block. Machined a custom billet fuel block for the existing fuel rails.
I used the following major components in this build;
UMI K-member (modified)and control arms
Dirty Dingo adjustable LS engine mounts
MegaSquirt MS3 EVOPro ECM with a flying harness
OBX SS ZR1 headers, modified for the 3rd gen cross member
Holley 2.5” true dual SS header back exhaust system
Custom crank trigger based off the Holley kit
Custom dual 3” intake
4th Gen fuel tank with a Aeromotive 340 LPH pump
New 3/8” SS fuel lines from the tank to engine compartment
BMR remote mount battery tray
Fidanza flywheel
Per Marc Haibeck, based on the engine mods I have done this should be putting out 450+ HP at the crank based on his experience with these changes. On my first outing I can tell you this thing is crazy fast with a 7,500 RPM redline compared to the old TPI engine
For those of you not familiar with the engine or need a refresher as there are many incorrect posts about this engine please see the link below;
Cost wise this came out very close to a high end LS swap and parts are plentiful you just need to know where to look.
A big shout out to my son Cody who was with me all the way, my very good friend Soloc4, Bruce and his crew at Hawks, Mario from the Dub Shop for MegaSquirt tuning, Jerry’s gaskets, and Marc Haibeck ZR1 expert extraodinaar.
Amazing, just amazing! Right there is the next "car of the month". Always loved the LT5, power has surpassed it, but it still remains a star.
Modified fiberglass heater box Bell housing starter ear removed for header clearance. LT5 starter is in the lifter valley area Modified OBX ZR1 headers. First 2 tubes rerouted to clear the crossmember and the new fiberglass air inlet to the side of the photo Custom LSX high perf coils and custom mount. Originally was a waste fire engine
More detailed work behind this build
Man this is awesome!! A lot of ingenuity went into the swap which makes it even better you did it yourself. Appreciate the detailed thread too. What is your profession if you don’t mind me asking?
Edit: The reason I ask is clearly you've got some mechanical skills and access to some cool tools.
Nothing fancy, new bearings, Ratech pinion crush sleeve, Motive 3.7 gear set and a truss cover. I set the gear lash tolerances to the low end of the range with a solid tooth contact pattern. I know I am at the upper end of the torque limit for the 9 bolt but I do not drop the clutch and abuse it, we'll see this summer how it does.
I have finished the last of my major updates under my car. I have installed UMI's subframe connectors. Due to the fact that I am not running the stock exhaust I beefed up the passenger side subframe connector that connects from the UMI bracket across to the front subframe. I replaced the short little 1" cross brace with a 1 1/2" square tube. I have also installed Founders LCA brackets and boxed in my lower control arms since the had new bushings in them.
Turning my attention to the front end I wanted to fine tune my ride height so I installed a pair of UMI weight jacks to provide that ability. So happy to be done with these updates, I can't wait for the weather to break now.
UMI subframe and Founders LCA brackets Boxed in lower control arm So easy to install compared to standard springs Modified pass side with heavier cross brace compared to the kit provided brace
Modified fiberglass heater box Bell housing starter ear removed for header clearance. LT5 starter is in the lifter valley area Modified OBX ZR1 headers. First 2 tubes rerouted to clear the crossmember and the new fiberglass air inlet to the side of the photo Custom LSX high perf coils and custom mount. Originally was a waste fire engine
More detailed work behind this build
What did you do to integrate the trans to the engine?
Interestingly, GM I their infinite wisdom had Lotus maintain the standard Chevy bell housing, crank to flywheel mating surfaces and pilot bearing the same dimensions as a LT1/L98 smallblock. I was able to reuse the T56 I had in my car from a 97 Camaro. I did need to drill and tap 1 bell housing bolt and cut the starter ear off the bell housing for header clearance. Fidanza had a 8 bolt flywheel the matched my old LT1 flywheel. So fire a lot of measuring and calculating it all worked out.
In 2018 my IROC vert was finally painted in a Lexus tri-coat white color.
Then in 2019 I saw a 1990 ZR1 LT5 engine for sale with only 17K miles on it. I gotta tell you this is one of my favorite engines of all time and I had to have it.
OBX SS ZR1 headers
Those look like the louvers Mr. IROC-Z had on his carbon fiber IROC hood. I like that they're so open and allow a great view of the LT5, sort of an IROC version of a C6 ZR1 hood window. In the category of engines worthy of being on display, the C4 LT5 is definitely one.
I was curious about the paint color. It looks like a soft, pale, cool, grey tone, rather than a bright white, but it could just be the lighting. It works well with your silver and grey accents and interior.
For the dreamer in others of us, there are two LT5 engines for sale on ebay that I've been watching for several months.
Your car should be a poster child for OBX. Somewhat of an "ebay" brand, basically big brand knockoffs, but the products look good, and the prices are very reasonable. Nice to see them on such a major project. New OBX headers and y-pipe are still floating around for TPI engines, like a Hooker 2055 knockoff, for about half the price of the Hookers.
Thanks, yes Mr. IROC Z inspired my hood louver cutouts. The color is a 2015 Toyota/Lexus tri-coat white. It is a white metallic base with a pearl on top then clear coated. I just couldn't go back to refrigerator white.
I have started my winter projects. First off was installing an adjustable UMI panhard bar to center my rear axle.
The second update was going with the UMI camber plates and ditching the stock ones. The old plates left some nasty paint lines so I sanded down the strut towers and resprayed them.
I have also pulled my T-56 trans and sent it off to Tick for a rebuild and some upgrades. Pulled the clutch while I was at it and ordered a McLeod Super Street Pro clutch.
More winter time projects. I have installed a UMI on-car adjustable panhard bar to get my axle back centered. Pulled the T56 and shipped it back to Tick Perf. for a full rebuild with some upgraded goodies. Installed a McLeod Super Street Pro clutch. I also picked up at SEMA this last fall one of Red Roberts Quik Stik shifters. Red was the founder of McLeod clutches, very interesting guy with lots of stories. Also replaced my speedo cable that got fried during my Dyno session .
I can't wait for spring here in the PNW to drive with my new upgrades.
To answer a few questions I have received on my build concerning what I started with. Back in April of 2014 I found my car on a local CL add. It had been parked for 6 years and was some kids old high school car. It was amazingly rust free but very moldy and smelly but I just had to have it. Original plan was to restore it but after tearing into it it just wasn't that car, so I went the restomod route and never looked back. Here is what it looked like when it was towed home and washed it for the first time.
Since completing my built last year I have gotten some media exposure. An article on my car just dropped this morning in Chevy Hardcore magazine, check it out at; https://www.chevyhardcore.com/featur...9-iroc-camaro/
Here is an Instagram clip from RADWood PNW last summer by car host Chris Jacobs;
12-27-2021, 02:29 PM
