ZZ3 Turbo Iroc - Round Three
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From: Panama City FL
Car: 87 Iroc
Engine: Turbocharged 5.7 Pro-Fl-XT
Transmission: 700R4 for moment
Axle/Gears: 3.25 9 inch
Re: ZZ3 Turbo Iroc - Round Three
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From: Pittsburgh PA
Car: 89 Iroc-z
Engine: 555 BBC Turbo
Transmission: TH400
Axle/Gears: MWC 9” 3.00
Re: ZZ3 Turbo Iroc - Round Three
I had a cam once that was off spec. Tried degreeing it at the dot to dot marks and was way off
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From: Pittsburgh PA
Car: 89 Iroc-z
Engine: 555 BBC Turbo
Transmission: TH400
Axle/Gears: MWC 9” 3.00
Re: ZZ3 Turbo Iroc - Round Three
Option 1. These cars arent to bad to do cam swaps on so shouldnt be bad to just degree it.
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Re: ZZ3 Turbo Iroc - Round Three
You could be right on the lifter being pumped down. I don't recall, what's your cranking PSI? Did you lose any after putting in this cam compared to the old setup? You could have a ton of power if your cam's off.
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Re: ZZ3 Turbo Iroc - Round Three
Are you sure you measured the lift at .050" properly? 1.5 rockers means .075" at the valve.
I would do the following before tearing apart or ordering anything.
1) verify the cam card for ICL and intake open @ .050" is correct. Some places mess up the +/- and the ATDC and BTDC.
2) Ensure the (pi*D) = 3.14 * 8" is correct.......that the balancer is 8"
3) Double check the (114/360)*(3.14*8") is correct and tape to balancer
4) Loosen cyl #1 rocker. Put something around pushrod to keep stationary relative to head pushrod hole or valve guide. Setup dial indicator on pushrod with valve on the base circle. Record dial indicator value. Spin engine until pushrod lifts .050" and look at balancer, then do this for max lift and look at balancer.
EDIT: putting some lines 2 degrees apart in visio works. Set the snap grid to (2/360)*(3.14*8).
I would do the following before tearing apart or ordering anything.
1) verify the cam card for ICL and intake open @ .050" is correct. Some places mess up the +/- and the ATDC and BTDC.
2) Ensure the (pi*D) = 3.14 * 8" is correct.......that the balancer is 8"
3) Double check the (114/360)*(3.14*8") is correct and tape to balancer
4) Loosen cyl #1 rocker. Put something around pushrod to keep stationary relative to head pushrod hole or valve guide. Setup dial indicator on pushrod with valve on the base circle. Record dial indicator value. Spin engine until pushrod lifts .050" and look at balancer, then do this for max lift and look at balancer.
EDIT: putting some lines 2 degrees apart in visio works. Set the snap grid to (2/360)*(3.14*8).
Last edited by junkcltr; Nov 25, 2014 at 04:27 PM.
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Car: 87 Iroc
Engine: Turbocharged 5.7 Pro-Fl-XT
Transmission: 700R4 for moment
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Re: ZZ3 Turbo Iroc - Round Three
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Re: ZZ3 Turbo Iroc - Round Three
It sounds like you did it right. Measure ICL by the .050" point before and after ICL and then find center of that in terms of degrees for ICL.
Only other thing I can think of is making sure the harmonic 0* mark is correct as compared to TDC.
Could also just do the .050" opening and .050" closing point for intake and then calc ICL from that. That is how I do it. It sounds like you are "there" in terms of the .050" open point. I bet the .050" closing is correct too and the ICL falls into place from that calc. ICL directly is harder to measure.
Either way, being advanced or retarded 4* is not going to make it quit revving like you described. With the wheel in the turbine it gives flow direction. Without it, massive turbulent flow.
EDIT: I don't see the pressure of the dial indicator causing a leak down problem.
Only other thing I can think of is making sure the harmonic 0* mark is correct as compared to TDC.
Could also just do the .050" opening and .050" closing point for intake and then calc ICL from that. That is how I do it. It sounds like you are "there" in terms of the .050" open point. I bet the .050" closing is correct too and the ICL falls into place from that calc. ICL directly is harder to measure.
Either way, being advanced or retarded 4* is not going to make it quit revving like you described. With the wheel in the turbine it gives flow direction. Without it, massive turbulent flow.
EDIT: I don't see the pressure of the dial indicator causing a leak down problem.
Last edited by junkcltr; Nov 25, 2014 at 05:49 PM.
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From: Panama City FL
Car: 87 Iroc
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Re: ZZ3 Turbo Iroc - Round Three
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Re: ZZ3 Turbo Iroc - Round Three
Looks great. Instant 50HP pickup right there. Where do you get the turbine outlet flange, or does yours match up?
I would call the cam good for now, install the turbo, and let er rip.
I would call the cam good for now, install the turbo, and let er rip.
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Re: ZZ3 Turbo Iroc - Round Three
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From: Lincoln, Illinois
Car: 92 Trans Am, 87 Formula
Engine: 305 soon to be TBI, 91 305 TPI swap
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Re: ZZ3 Turbo Iroc - Round Three
I've been following this build for a long time. i have talked to you before on YouTube, i have ZZ3 too.
did you get a new cam? i read some of this thread (not every post) i couldnt find what cam you chose.
I'm a huge fan of TPI but i really think you can go way faster at this point with a Holley Stealth Ram. it would add some power and you would lose a little bit of the low end torque that will help with any traction issues I'm pretty sure after this winter my ZZ3 is getting a Stealthram and may an LT4 hot cam. I've been cam shopping for about a year now and i still can't make up my mind. i dont wanna have to upgrade half my motor or half of my car just for a cam.
did you get a new cam? i read some of this thread (not every post) i couldnt find what cam you chose.
I'm a huge fan of TPI but i really think you can go way faster at this point with a Holley Stealth Ram. it would add some power and you would lose a little bit of the low end torque that will help with any traction issues I'm pretty sure after this winter my ZZ3 is getting a Stealthram and may an LT4 hot cam. I've been cam shopping for about a year now and i still can't make up my mind. i dont wanna have to upgrade half my motor or half of my car just for a cam.
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From: Panama City FL
Car: 87 Iroc
Engine: Turbocharged 5.7 Pro-Fl-XT
Transmission: 700R4 for moment
Axle/Gears: 3.25 9 inch
Re: ZZ3 Turbo Iroc - Round Three
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From: Panama City FL
Car: 87 Iroc
Engine: Turbocharged 5.7 Pro-Fl-XT
Transmission: 700R4 for moment
Axle/Gears: 3.25 9 inch
Re: ZZ3 Turbo Iroc - Round Three
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Re: ZZ3 Turbo Iroc - Round Three
perfect project for the plasma cutter. get some 5/16-3/8" plate, cut out a piece that will bolt onto the turbo, drill 2 bolt holes, and then tap it to whatever you need it to be. 1/8-1/4" pipe or whatever your fitting is. tap should be available at lowes/homedepot etc.
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Transmission: 700R4 for moment
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Re: ZZ3 Turbo Iroc - Round Three
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Re: ZZ3 Turbo Iroc - Round Three
i donno, im thinking 4 deg. advanced might actually be ok with the tpi intake? when you dynoed it, where was peak hp rpm?
im anxious to see how the new turbo does!
im anxious to see how the new turbo does!
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Re: ZZ3 Turbo Iroc - Round Three
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I think every time I've dynoed this engine it has been mph based. On the rpm based ones in the past, the stall makes the start around 4000-4500 and the peak hp was always at the beginning and falls off. Same thing for the mph based one. Power shoots straight up at 65 mph, peaks at 80 and declines the whole pull. Peak hp of 532 at 85 mph and down to 460 at 114.
3.27 ratio and 25" tall tires.. Not accounting for the converter slip:
85 mph is 3736 rpm
114 mph is 5001 rpm
Your guess is as good as mine on converter slip.. probably 8-10% so 5500 rpm for the 114. Sounds about right from what the tach is doing.
3.27 ratio and 25" tall tires.. Not accounting for the converter slip:
85 mph is 3736 rpm
114 mph is 5001 rpm
Your guess is as good as mine on converter slip.. probably 8-10% so 5500 rpm for the 114. Sounds about right from what the tach is doing.
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Car: 89 Iroc-z
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Transmission: TH400
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Re: ZZ3 Turbo Iroc - Round Three
I dont think 110 cl is gonna be killing the car that much. The dense air may just be exacerbating the tpi's tuned range. Hard to say but willing to bet a shorter runner intake would eliminate the problem or a siamesed runner setup
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Re: ZZ3 Turbo Iroc - Round Three
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Car: 87 Iroc
Engine: Turbocharged 5.7 Pro-Fl-XT
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Re: ZZ3 Turbo Iroc - Round Three
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Car: 89 RS 89 iroc 87 firebird
Engine: 3.1 Turbo/ 355 twin turbo
Transmission: a4 w/ 4500 stall/ a4 / t5
Axle/Gears: strange s60 /w 3:42's
Re: ZZ3 Turbo Iroc - Round Three
Decided to keep the cam advanced 4 degrees between my research and what you guys have input. Results are in.. as expected, spooling sucks compared to the PT6766. Power takes forever to come in and right when there is a hint of go I am out of rpm. Just very lackluster overall at 16.5 psi.. with a 78 at that boost level, assuming no insane restrictions, it should be an intense ride. It's not.
I have a few ideas of how to proceed...
I can test intake runner and lower intake restrictions by connecting a second boost gauge to the cold start injector location. I would expect a 5 psi drop at 5000 rpm from the upper plenum pressure to the cylinder head inlet (semi-close to the cold start plumbing. This drop estimate is based on the length and diameter of the stock tpi runners and estimated flow/psi. If the drop is much higher than that, the intake is the biggest restriction. If it is less than that, the heads or cam would be the source of the restriction.
I can eliminate the intake also by changing it. I have a blow thru carb available and the original intake and distributor from the ZZ3. This would be an easy swap and ironically is the first step towards removing the engine anyway. Also I can just do this N/A to see if the 4000 wall is still there.
I've been debating intake/heads/cam ugprades but I keep thinking it might be time to do a 5.3. Certainly my current setup is not going to work as it is.
I have a few ideas of how to proceed...
I can test intake runner and lower intake restrictions by connecting a second boost gauge to the cold start injector location. I would expect a 5 psi drop at 5000 rpm from the upper plenum pressure to the cylinder head inlet (semi-close to the cold start plumbing. This drop estimate is based on the length and diameter of the stock tpi runners and estimated flow/psi. If the drop is much higher than that, the intake is the biggest restriction. If it is less than that, the heads or cam would be the source of the restriction.
I can eliminate the intake also by changing it. I have a blow thru carb available and the original intake and distributor from the ZZ3. This would be an easy swap and ironically is the first step towards removing the engine anyway. Also I can just do this N/A to see if the 4000 wall is still there.
I've been debating intake/heads/cam ugprades but I keep thinking it might be time to do a 5.3. Certainly my current setup is not going to work as it is.
right now im thinking about a set of the 60mm t70's or a pair of on 3 66's
if i knew i could spool them id drop a set of gt45's on it .
second put an clone hsr on it for 200 bucks + 50 bucks for the fuel rails
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Re: ZZ3 Turbo Iroc - Round Three
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Re: ZZ3 Turbo Iroc - Round Three
what condition is the t70 in might be willing to trade ya a bigger turbo or something for it
think ive got some big old school garetts and holsets laying around
think ive got some big old school garetts and holsets laying around
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Car: '88 Iroc
Engine: Single turbo Vortec 5.7, Megasquirt
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Re: ZZ3 Turbo Iroc - Round Three
I'm curious as to how much timing you are currently running. Our setups are not extremely similar, but I always like comparing. I have been running around 20-22 degrees of timing over 3000rpm at 10psi (180kpa). I haven't ran higher boost yet but this seems to be about as high as I can go and be a couple degrees shy of the detonation threshold. I'm running cast iron vortec heads with a 212/222 cam with a performer rpm intake and a blow through setup running low 11 AFR's.
Regarding the lower exhaust backpressure (theoretical with the larger turbo), I noticed a definite difference in how much timing mine would tolerate whether I had my full exhaust vs an open downpipe. If I remember right, it would handle about 3-4 degrees more advance with the open setup.
Regarding the lower exhaust backpressure (theoretical with the larger turbo), I noticed a definite difference in how much timing mine would tolerate whether I had my full exhaust vs an open downpipe. If I remember right, it would handle about 3-4 degrees more advance with the open setup.
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Car: 87 Iroc
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Transmission: 700R4 for moment
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Re: ZZ3 Turbo Iroc - Round Three
Project89, it wasn't burning oil or anything but it has about 10k miles on it. Biggest thing is a good bit of radial play but only about 1/2 what the Precision has. Are you just looking to mock it up or use it?
Vortec350s10, I have to refresh my memory on the timing error on my MS but I think it is about 5 degrees at 5000 rpm. Until tonight I was running the following:
4900 rpm 15.2 psi 20.1 degrees (25.1 in the map)
3700 rpm 15.2 psi 13.5 degrees (17.0 in the map)
4900 rpm 10 psi 24.0 degrees (29.0 in the map)
3700 rpm 10 psi 15.7 degrees (19.2 in the map)
This evening I bumped that up a bit to the following with no detonation:
4900 rpm 15.2 psi 22.2 degrees (27.2 in the map)
3700 rpm 15.2 psi 15.8 degrees (19.3 in the map)
4900 rpm 10 psi 24.9 degrees (29.9 in the map)
3700 rpm 10 psi 19.8 degrees (22.3 in the map)
I found the tpi setup to be very prone to detonation in the 3000-3500 range and have always been conservative there.
Vortec350s10, I have to refresh my memory on the timing error on my MS but I think it is about 5 degrees at 5000 rpm. Until tonight I was running the following:
4900 rpm 15.2 psi 20.1 degrees (25.1 in the map)
3700 rpm 15.2 psi 13.5 degrees (17.0 in the map)
4900 rpm 10 psi 24.0 degrees (29.0 in the map)
3700 rpm 10 psi 15.7 degrees (19.2 in the map)
This evening I bumped that up a bit to the following with no detonation:
4900 rpm 15.2 psi 22.2 degrees (27.2 in the map)
3700 rpm 15.2 psi 15.8 degrees (19.3 in the map)
4900 rpm 10 psi 24.9 degrees (29.9 in the map)
3700 rpm 10 psi 19.8 degrees (22.3 in the map)
I found the tpi setup to be very prone to detonation in the 3000-3500 range and have always been conservative there.
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From: Minnesota
Car: '88 Iroc
Engine: Single turbo Vortec 5.7, Megasquirt
Transmission: Probuilt 700r4 3000 stall Vigilante
Axle/Gears: Moser 9" 3.25 w/True Trac
Re: ZZ3 Turbo Iroc - Round Three
I would bet the 3000-3500 rpm range is where you are making the most torque. Is that where your VE numbers are highest? How are you getting your rpm signal for the MS? I ran my MSD box rpm signal off of the pickup coil in the distributor and with the timing programmed to a constant value, it would still advance itself about 5-6 degrees when revving it vs idle. I always chalked it up as cam walk and timing chain. I'd be curious to see your msq sometime if you don't mind sharing. I'm currently converting over to a MS3 setup from the carb right now. I'm going to install a 36-1 wheel on the crank for an rpm signal to hopefully get away from the timing variance I'm currently seeing. Thanks for sharing your timing.
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Project89, it wasn't burning oil or anything but it has about 10k miles on it. Biggest thing is a good bit of radial play but only about 1/2 what the Precision has. Are you just looking to mock it up or use it?
Vortec350s10, I have to refresh my memory on the timing error on my MS but I think it is about 5 degrees at 5000 rpm. Until tonight I was running the following:
4900 rpm 15.2 psi 20.1 degrees (25.1 in the map)
3700 rpm 15.2 psi 13.5 degrees (17.0 in the map)
4900 rpm 10 psi 24.0 degrees (29.0 in the map)
3700 rpm 10 psi 15.7 degrees (19.2 in the map)
This evening I bumped that up a bit to the following with no detonation:
4900 rpm 15.2 psi 22.2 degrees (27.2 in the map)
3700 rpm 15.2 psi 15.8 degrees (19.3 in the map)
4900 rpm 10 psi 24.9 degrees (29.9 in the map)
3700 rpm 10 psi 19.8 degrees (22.3 in the map)
I found the tpi setup to be very prone to detonation in the 3000-3500 range and have always been conservative there.
Vortec350s10, I have to refresh my memory on the timing error on my MS but I think it is about 5 degrees at 5000 rpm. Until tonight I was running the following:
4900 rpm 15.2 psi 20.1 degrees (25.1 in the map)
3700 rpm 15.2 psi 13.5 degrees (17.0 in the map)
4900 rpm 10 psi 24.0 degrees (29.0 in the map)
3700 rpm 10 psi 15.7 degrees (19.2 in the map)
This evening I bumped that up a bit to the following with no detonation:
4900 rpm 15.2 psi 22.2 degrees (27.2 in the map)
3700 rpm 15.2 psi 15.8 degrees (19.3 in the map)
4900 rpm 10 psi 24.9 degrees (29.9 in the map)
3700 rpm 10 psi 19.8 degrees (22.3 in the map)
I found the tpi setup to be very prone to detonation in the 3000-3500 range and have always been conservative there.
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From: Utah
Car: 89 RS 89 iroc 87 firebird
Engine: 3.1 Turbo/ 355 twin turbo
Transmission: a4 w/ 4500 stall/ a4 / t5
Axle/Gears: strange s60 /w 3:42's
Re: ZZ3 Turbo Iroc - Round Three
or maybe even the garett 66mm compressor wheel and housing
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Re: ZZ3 Turbo Iroc - Round Three
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From: Lincoln, Illinois
Car: 92 Trans Am, 87 Formula
Engine: 305 soon to be TBI, 91 305 TPI swap
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Re: ZZ3 Turbo Iroc - Round Three
yea im gonna say its too tall. ive got a low rise intake and carb on my 92 firebird with a stock trans am hood and i have to use an insanely small filter, Camaro do have a lil more room but youll probably need a cowl hood to run that intake.... but im not an expert or anything
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From: Minnesota
Car: '88 Iroc
Engine: Single turbo Vortec 5.7, Megasquirt
Transmission: Probuilt 700r4 3000 stall Vigilante
Axle/Gears: Moser 9" 3.25 w/True Trac
Re: ZZ3 Turbo Iroc - Round Three
My friend ran a Spectre low profile carb hat that was the lowest he could find. Although I'm not sure if you would run a 4150 style TB or do an elbow and run your TPI TB or go with a LS style. I'm not sure what would be the lowest setup. I know I'll be using at least 2" of my 3" cowl for clearance on mine. I'm going to run a RHS single plane EFI intake (12903) and it's probably taller than the Procomp. I think most anything would be a challenge fitting under the stock hood.
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Car: 87 Iroc
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Transmission: 700R4 for moment
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Re: ZZ3 Turbo Iroc - Round Three
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Re: ZZ3 Turbo Iroc - Round Three
I remember you looking into the MS ECM spark latency before. The stock TPI ignition module averages about 200 microseconds of latency. At 6000 RPM, the crank takes 10,000 microseconds per revolution which is 10,000/360 = 28 microseconds per degree.
So, 200/28 = 7 degrees.
If the MS2 doesn't take into account the module latency then your timing is 7 degrees retarded from where you think it is at.
Good move with the cam, I would have left it where it was at too.
Not sure why it takes so long to spool. Stock 305ci with two 54mm compressors makes 15PSI by 3500 RPM.
So, 200/28 = 7 degrees.
If the MS2 doesn't take into account the module latency then your timing is 7 degrees retarded from where you think it is at.
Good move with the cam, I would have left it where it was at too.
Not sure why it takes so long to spool. Stock 305ci with two 54mm compressors makes 15PSI by 3500 RPM.
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Re: ZZ3 Turbo Iroc - Round Three
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Re: ZZ3 Turbo Iroc - Round Three
u can ditch the module and do direct coil control, rotor phasing will also have an impact on spark timing performance
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Re: ZZ3 Turbo Iroc - Round Three
What do you have it set to now?
There are two parts to the spark latency:
1) The time for the signal from the detection of the "tooth" to the ECM seeing the signal.
2) The time from the ECM sending the "coil fire" signal through the switch (IGBT,BJT,MOSFET) to the coil.
Even the "direct coil" control method has spark hardware latency.
Last edited by junkcltr; Dec 3, 2014 at 04:22 PM.
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Car: 87 Iroc
Engine: Turbocharged 5.7 Pro-Fl-XT
Transmission: 700R4 for moment
Axle/Gears: 3.25 9 inch
Re: ZZ3 Turbo Iroc - Round Three
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Last edited by ZZ3Astro; Sep 23, 2015 at 12:05 PM.
Thread Starter
Supreme Member
Joined: Jul 1999
Posts: 1,773
Likes: 7
From: Panama City FL
Car: 87 Iroc
Engine: Turbocharged 5.7 Pro-Fl-XT
Transmission: 700R4 for moment
Axle/Gears: 3.25 9 inch
Re: ZZ3 Turbo Iroc - Round Three
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Last edited by ZZ3Astro; Sep 23, 2015 at 12:05 PM.
Joined: Sep 2003
Posts: 25,895
Likes: 429
From: Pittsburgh PA
Car: 89 Iroc-z
Engine: 555 BBC Turbo
Transmission: TH400
Axle/Gears: MWC 9” 3.00
Re: ZZ3 Turbo Iroc - Round Three
Go co2 and add 40 psi to that gate.
I think it would be hard to tell how much power its making without track or dyno tune. Hard to feel that power level difference
I think it would be hard to tell how much power its making without track or dyno tune. Hard to feel that power level difference
Supreme Member
iTrader: (1)
Joined: Jan 2002
Posts: 4,432
Likes: 1
From: garage
Engine: 3xx ci tubo
Transmission: 4L60E & 4L80E
Member
Joined: Dec 2012
Posts: 161
Likes: 1
From: Lincoln, Illinois
Car: 92 Trans Am, 87 Formula
Engine: 305 soon to be TBI, 91 305 TPI swap
Transmission: 700R4
Axle/Gears: 10 bolt
Re: ZZ3 Turbo Iroc - Round Three
Dont go darkside... ok a LS swap isnt darkside. i said it once ill say it again lol i really think with everything your ZZ3 has on it you would upgrade to a Holley Stealthram. you probably make peak power in the 4,700 - 4,900 RPM range now with your TPI setup, but with your current heads and cam you could be making peak power at 6,000 RPM. ive seen a 400 horsepower TPI engine turn into 500 horsepower Holley stealthram engine, just swapping the intake. ADD in your turbo and you can imagine the horsepower your current motor has the possiblity of making. im telling you its gonna be the best $600 you spent. you could even buy one of the Ebay $300 rip offs if you wanna save a few bucks. speed master i think makes one too. i think with just the intake and redoing the tune to match the intake youll be a happy man. and no need for a cowl hood, the stealthram will fit under it. i have to modify my formula's hood to make the stealthram fit under my hood... wish i still had my
IROC lol
IROC lol
Joined: Dec 2005
Posts: 6,499
Likes: 31
From: Macon, GA
Car: 1992 Camaro RS
Engine: Vortec headed 355, xe262
Transmission: T56
Axle/Gears: 9-bolt 3.70
Re: ZZ3 Turbo Iroc - Round Three
Why not take it to the track and see what it does before you start LS swap it? I mean can you really tell the difference at these power levels with the kind of torque a TPI system will make? That torque curve is going to be insane, and it may not pick up much on the high end the way you expect, but it'll still pick it up in the mid range.
Thread Starter
Supreme Member
Joined: Jul 1999
Posts: 1,773
Likes: 7
From: Panama City FL
Car: 87 Iroc
Engine: Turbocharged 5.7 Pro-Fl-XT
Transmission: 700R4 for moment
Axle/Gears: 3.25 9 inch
Re: ZZ3 Turbo Iroc - Round Three
gone
Last edited by ZZ3Astro; Sep 23, 2015 at 12:07 PM.
Senior Member
Joined: Mar 2014
Posts: 571
Likes: 10
From: Indy
Car: 88 IROC-Z
Engine: GEN 4 LY6 (going forged 408)
Transmission: 60E (going RPM LEVEL 6 4L80E)
Axle/Gears: 7.5" 3.42 (staying...)
Re: ZZ3 Turbo Iroc - Round Three
Just run it on the street/highway and stop crying. Be thank full for what you have.
Senior Member
Joined: Mar 2014
Posts: 571
Likes: 10
From: Indy
Car: 88 IROC-Z
Engine: GEN 4 LY6 (going forged 408)
Transmission: 60E (going RPM LEVEL 6 4L80E)
Axle/Gears: 7.5" 3.42 (staying...)
Re: ZZ3 Turbo Iroc - Round Three
Hey OP, what size coupler on you running on the TB?
(I bought a 3" to 4" and it seams like it might be to big / haven't put a clamp on it yet)
(I bought a 3" to 4" and it seams like it might be to big / haven't put a clamp on it yet)
Thread Starter
Supreme Member
Joined: Jul 1999
Posts: 1,773
Likes: 7
From: Panama City FL
Car: 87 Iroc
Engine: Turbocharged 5.7 Pro-Fl-XT
Transmission: 700R4 for moment
Axle/Gears: 3.25 9 inch
Re: ZZ3 Turbo Iroc - Round Three
TB fits 4". I can't remember if it went on loose or tight though. Seems like it was a good fit but its been years!
Senior Member
Joined: Mar 2014
Posts: 571
Likes: 10
From: Indy
Car: 88 IROC-Z
Engine: GEN 4 LY6 (going forged 408)
Transmission: 60E (going RPM LEVEL 6 4L80E)
Axle/Gears: 7.5" 3.42 (staying...)
Re: ZZ3 Turbo Iroc - Round Three
I put it on and their was about 1/4 of material on the coupler that was "loose".