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Car is 1986 IROC owned since high school..over 20yrs ago. The car will be built for the street, so am looking for huge torque and excellent driveability. I don't want to have to spin the motor up like the LT1 that's coming out to make power. It has to have/keep the AC..that hasn't been installed since about 1995 in this car, and will be needed to do some serious touring..like the Powertour!
More history.. I swapped a T56 into it in 1999 as it was cheaper than rebuilding the 700R4. This is before everyone and their brother was swapping T56's, so all the parts cost me about $1,000!
Next up in 2002 was an iron head LT1 swap that in 2007 got a Lloyd Elliot 2.2 heads and cam package. The iron head with stock cam went 13.8's on 3.23 gears. Decent power for what it was.
Along with the LT1, I put a 9-Bolt Borg Warner (M78) axle to replace the weak stock 10-Bolt and 3.5" PST aluminum driveshaft. The 9-Bolt got 4.10 gears a few years later with the H/C swap. This really woke the car up, running a 12.6 at 114MPH on a base mail order tune on drag radials.
The car got a brake upgrade to C4HD fronts and LS1 rears in 2008. I was shocked at how much better the car braked. It always had 4 wheel disk, but this was a whole new level.
I've always wanted to boost the car, so sold the LT1 as the 11.1 compression and GM PCM is difficult to tune for positive pressure. I sold the motor in 2013 to a friend who swapped it into a 65 Lemans and also to pay for a few goodies. I picked up a 2006 LQ4 24x with 126,000kms (76,000 miles) from a local wrecker for $1,000 complete with harness and PCM. The engine has 317 heads and being 24x decided to run the 0411 PCM with HP Tuners Pro & NGK AFX wideband. Plan is to get it up and running NA with a 2 bar OS, learn to tune, put in a good solid base tune, and then completely fabricate and install the intercooled, meth injection turbo system. I started the LQ4 swap in 2013 and didn't get it on the road N/A until early summer of 2015. It took a lot more effort than I thought, even having swapped the LT1 before.
After some research I picked up a used Turbonetics TC76, and also found a deal on a JGS 40mm 400R Wastegate, and JGS 50mm BOV. The turbo has the 68mm F1 exhaust wheel with a 1.15AR housing, so should flow decently as the unit is definitely on the small side for a 6.0L. I want quick spool, and lots of guys have run this unit successfully. The turbo also had to be small so I don't have to cut the car up to fit it.
BTW the book "Maximum Boost - Designing, Testing and Installing Turbocharged Systems by Corky Bell" is a must read for learning about turbo charging.
Here is the LT1 swap..I ran this motor for 10 years without a single issue.
The LQ4 iron block was needled to remove the rust scale and painted with KBS Motor Coater. Stuff is awesome.
Katech Rod Bolts
Installing 2002 LS6 Cam #12565308
Going back together..
Just about to put the PAC 1218 springs in
K-Member before & during notching. Fit check with LS1 AC compressor. Had to notch K-member for AC and oil pan clearance.
Used Spohn LSX Swap Motor Mounts, but I may have to modify them as I'm not happy with the driveline angles as they are on the high end..
After.. with port installed and capped for turbo oil return to the pan..
Engine in.. can see the Katech solid adjustable tensioner.
I also did an Astro van steering shaft upgrade to replace the stock one that has a rag joint. This is a good upgrade and a no brainer when you compare the hardware.
Here is the link to the build thread on Thirdgen.org http://www.thirdgen.org/forums/suspe...-steering.html
F-Body accessories & intake, tapped water pump for steam line connection. Used 1995 Corvette throttle body bellows and IAT. It fits the round cable Truck TB perfectly.
If I did it again I'd but all new accessories. Ended up replacing a used alternator and the power steering pump.
Last edited by 6speediroc; 06-23-2017 at 10:39 PM.
Checking the truck manifolds with AC box for turbo. I'll need to trim the AC box outer inside edge a little for manifold clearance, but bought a second box to modify so can keep all the stock parts. Should be able to easily run a 3" downpipe, maybe a 3.5" under the RH manifold.. I haven't seen one thirdgen with a turbo and working AC, but I'll do it.
Last edited by 6speediroc; 01-30-2016 at 10:13 PM.
Custom stainless Y-pipe for LS1 manifolds to run before boosting. I used the stock LS1 F-body flex joint and flanges. Tubing is 2.5" 0.065" wall 304SS sanitary tubing merging into 3".
Getting a little ahead, but wanted to show the fit!
T56 Teardown & Rebuild for LS.
As the car has the T56 with the LT1 I decided to convert it to LS1 as I knew it was in very good shape and didn't want to risk selling and buying a piece of junk.
Here is the 5-6 Cluster on mainshaft that I discovered is an issue on these things. I always wondered what the knocking in the trans was at idle.. I sent it to Texas Drivetrain Performance for weld build and re-machine. They ended up sending me back a different already repaired mainshaft and cluster as the turn-around was too long to repair mine.
Home-made puller..it actually worked.
Installed billet keys, bronze pads, CF blocker rings, steel 3-4 fork from TheGearbox.org.
After finally driving the car, it would not shift smoothly into third. I tore it back down to find out the third blocker ring was cracked, so would not grip onto third gear during shifting. It either came like that or I broke it during the assembly if the keys were not lined up with the notches in the blocker. Shifts perfectly after replacing.
Put in a Spec 2+ clutch & SFI billet steel flywheel along with a Quicktime SFI bellhousing. The LT1 aluminum bellhousing always scared me when shifting a stock cast flywheel at 6300rpm.
Last edited by 6speediroc; 01-30-2016 at 10:14 PM.
Mishimoto 3 core aluminum rad. It fit with some minor tweaking of the upper plastic rad support and rubber spacers.
Used NAPA 8333 upper hose and Gates 20893 lower hose. The upper one doesn’t fitt 100% as it doesn’t sit in the upper rad support hose holder, but looks ok. I'll likely deal with this again later..
Air conditioning:
I made my own AC lines with the turbo placement in mind being where the battery is now. Used LS1 FBody hardlines near the compressor with crimp style fittings welded on, then crimped locally at a buddies refrigeration shop. The lines fit perfectly.
Used 3 wire AC Refrigerant pressure sensor Delco #15-72104/2259959
Stock 4th gen F-body AC hardlines.
New lines.
Had to make a new K-member brace as the stock one interfered with the compressor..
Last edited by 6speediroc; 01-30-2016 at 09:25 PM.
For the fuel system, I kept the stock TPI hardlines with original Oring end fittings and used the nylon style fittings from Dorman to get to the Corvette regulator/filter [WIX 33737] and the intake. This will change with the turbo. I borrowed the proper nylon line assembly tool from a buddy and it went together very easily. I already have a Racetronix hotwire kit and Walbro in-tank pump.
Here are the fittings used, all from Dorman:
Wiring, used re-worked truck harness and Current Performance fuse/relay kit for LS1. This thing is huge.. I may rewire using the Bussmann 15303-2-2-4 micro fuse panel. https://ls1tech.com/forums/conversio...relay-box.html
Used 4th gen F-body battery lead junction blocks on either side of the rad for power take-offs. Got them as reproductions from Hawks as they are no longer made. Helps to connect the alternator and headlight feeds as the battery is on the other side of the engine bay.
Here is my PCM mount for up under the dash that fits into the stock TPI ECM upper holder.
All the wires are labeled with PCM pin# and service with all factory wire colours. I wrapped the harness with Tesa 51025 harness tape. It’s great to work with and looks much nicer than plastic loom. We’ll see how it holds up over time. I used less than 3 rolls total. http://autoobsessed.com/shop/wiring-...ape-p-795.html
I also wired in an AFX wideband. This thing is great and dead simple to use with HP Tuners.
I made up a complete 0411 swap into a Thirdgen F-body wiring diagram in AutoCAD. It has all the required sensor part numbers, wire colours & guages for both the engine and the car. It will help if I ever have to diagnose an issue.
Wiring diagram thread: https://ls1tech.com/forums/conversio...g-diagram.html
Used 1998 LS1 3 wire coolant sensor in the head, 12551708. Works fine with stock guage. Also used 99-2002 oil pressure sender Delco D1818A, 1256267 with stock guage. These are all listed on my wiring diagram at the link above.
Last edited by 6speediroc; 10-20-2017 at 10:28 AM.
Using HP Tuners, I created a base tune with a stock LS6 vette file, keeping the LS6 VE tables, but with 2002 F-body timing to start. Changed the injector data for Bosch EV14 60lb/hr injectors (so have good room to grow power wise), then converted to a 2bar MAP tune with no MAF.
On the initial start-up the engine would fire, then die off in a few seconds with no throttle response. After checking and re-checking the base tune, injector data, VATS etc, I almost accidentally found the answer through a google search of HPTuners.com site.
HP Tuners gives instructions to convert the tune from 1bar to 2bar, but the instructions don’t tell you to enable DTC P0101, P0102, P0103 in the tune to set a code but no MIL. It fired immediately with this change! Strangely enough HP Tuners has no interest in adding this to the instruction file after asking about it..?
I currently have the car running very well with the VE map nicely tuned. I changed the timing to stock LS6 high octane, and still have to add timing as there is not a hint of knock.
The car runs strong still has 4.10 gears, and would do better with taller ones. I think my old LT1 pulled harder, but it may be deceiving because this thing is quieter and doesn’t pull as hard up in the revs, but it sure wraps up the speedo quickly!
After looking into the cost (insane..like $600+ for just the gears) of changing my BW 9-Bolt to 3.4x gears, decided to sell off all my Borg Warner 9-Bolt spares and 4.10 axle complete and build a Ford 8.8. They're plentiful, strong, and parts are cheap. Gear sets are only about $160 and you can get almost any ratio, and they all fit onto the same carrier.
Ford 8.8 build..winter 2015/2016:
I bought a custom fabricated 8.8 housing from a local guy who has built several of these and uses a dedicated jig and professional welder for the addition of the torque arm mount to the cast housing. The steel to cast welding was the main reason I didn't fabricate it myself. The 8.8 passenger car center section and about 8" of axles stubs are kept, welding in stock Thirdgen spring mounts still on stock tubes with new Moser #7900FM (flush mount) ends for Ford large taper bearings Timken #SET20 (ID= 1.5630” OD= 3.1496”). The FM ends let you use the backing plates as the bearing retainer and have the LS1 (1998+) rear backing plate bolt pattern.
The housing has the pinion offset ½” toward the passenger side to get the torque arm mount as close as possible to the stock position. It is still 1.75” closer to the drivers side.
Ordered some Moser 31 spline axles and Ford 3.50 gears and a Ratech complete bearing kit.
Picked up a used Explorer axle for the 31 spline Trac-loc carrier for $100.
I saved the pinion bearings to use as set-up bearings by opening up the bores with a drum sander. It only took a few minutes on a die grinder.
Also pulled an Explorer 8.8 IRS diff cover to save a few bucks on a new cover. It was a bitch to get off the Exploder..took 2.5hrs of my life as the pumpkin has to drop to get the cover off. The axles would NOT pull out on that POS. I ended up hacking the CV boots open to pull the half shafts out and it dropped. http://www.svtperformance.com/forums...to-fit-any-8-8
Last edited by 6speediroc; 09-08-2016 at 11:59 AM.
Nice fab work so far. I have a soft spot for these cars. Of my buddies in high school the first one to get his license had an 88 RS 305 in red. I remember vividly that the back seat sucked so bad it was better to just sit on the hump.
Be careful with that flex joint on the exhaust. Turbos always tear them up unless it's an interlocked style.
Ya I've seen that on the exhaust flexes.
That one is on the YPipe for the pre-turbo install exhaust and doesn't have a flexible liner in it anyways.. thanks for the heads up though.
Looks nice. I have had my car since 1996 and I too removed the LT1/auto and LS/t56 swapped it. Best thing I ever did to my car. Not many have kept AC and added a turbo so great job so far.
I'm waiting on you to pull this off so I can do the same I'm building a forged 6.0 for my 88' Iroc that I want to turbo but it's been on hold because I must keep the a/c.
I finally got the 8.8 back together. I couldn't get a pattern that I liked so had to bring it into a local guy who has set lots of these up and has the full ford pinion depth measuring stuff.
Here is the drive pattern with FMS gears and 0.019" shim and 0.007" backlash. Spec is 0.008 to 0.012", but the gears liked it a little tighter. The paint is wiped evenly across the gearface, but the dark spot isn't centered.. I was only looking at the position of the dark spot.
Here is the coast side..
Crappy pic..
Ford Explorer IRS cover with the ears cut off. I like this cover as it is one of the only options that has a drain and fill plug at the proper level & looks pretty good too!
01-30-2016, 08:24 PM
1986 IROC (to be Turbo) LQ4/T56 build with AC 
