IR89 - back in action.

Talk about anything and everything
Post Reply
ImpulseRocket89
Senior Member
Senior Member
Posts: 194
Joined: Thu Dec 16, 2010 3:00 pm
Location: Omaha, NE USA
Contact:

IR89 - back in action.

Post by ImpulseRocket89 » Wed Aug 15, 2012 9:56 am

I disappeared for a while. I had a back injury last June and only have recently recovered enough from my surgery to start working on my car again. Anyway, I figured I would fill you in on what I have been up to the last couple of weekends now that I can get to work again. I will try to keep the pictures to a minimum (I am camera happy lol)

I am sure a lot of you remember the V6 swap I was attempting. I ended up stopping on that project for now and decided to go with a 4ZE1 build instead. Due to my injury my finances are a bit short, so in making up for a lack of funds I decided to get as much done with what I have as I can, and get the car setup for fab work.

This is that 2.6 as I got it home (in the trunk of my other car no less)
Image

2 weeks ago I dismounted the factory MSG-5 transmission from the stock 2.0L assembly and removed the flywheel and clutch, and then stripped it down of everything I needed.
Image

Then took the above dirty 2.6, stripped it down, and put all of the 4ZC1 brackets, distributor, oil pan, and fuel rail on it. I also added a 97 Rodeo 2.6 upper plenum and single butterfly TB on the older 2.6's older lower plenum. I did my best to degrease it with some spray can stuff and a hose with a high pressure nozzle, but its still dirty looking, not that it matters at this point in time.
Image

Now for the gearbox, with the plans for the car I don't trust the stock MSG-5 transmission to hold the abuse and power that I am going to put it through, so I took the MUA-5 from the V6 swap attempt and got my hands on a 2.6 MUA5 front transmission case. I swapped over the Speedo drive from the stock impulse trans in place of the VSS from the rodeo (will be off with stock tire diameter and rear ratio, but that will be fixed).

This is a comparison of Impulse Speedometer drive vs. Newer VSS from the MUA-5. 17 Tooth driven with a 5 tooth drive gear in the Impulse, 21 tooth driven with a 6 tooth drive in the MUA. Currently it is a 17 tooth driven and 6 tooth drive, which with my future tire diameter and rear diff ratio works out almost perfectly.
Image

This is a much bigger/beefier transmission than the stocker, but the gear ratios mean I have to adjust the rear diff ratio to something taller (axle upgrade heh).
Image

The only thing I haven't swapped over to the trans yet is the impulse shifter and quadrant. The reason being is some machining has to be done to the flange/pad that the quadrant bolts to as well as the center plate on the top to allow the quadrant to sit down on it.

Thanks to the previous owner taking this car apart, I have been digging and searching for some of the factory parts (cruise servo etc). I finally located it and have to bolt it in, got the motor mounts located and re-installed, and killed myself to reinstall the brake booster and new master cylinder.
Image

Anyway, that is the progress I made over the course of the last 8 days. (3 solid days of work). To keep this post shorter I will post a few of the "why" for the need to fabricate, and why I am getting the motor and trans together for it.
1988 Isuzu Impulse Turbo.
2005 Ford Crown Victoria LX

RIP 1989 Impulse Turbo, aka "Rakete"

ImpulseRocket89
Senior Member
Senior Member
Posts: 194
Joined: Thu Dec 16, 2010 3:00 pm
Location: Omaha, NE USA
Contact:

Post by ImpulseRocket89 » Wed Aug 15, 2012 10:16 am

Anyway, all of that is so I can get the engine/trans in place to start fabricating the turbo manifold (and possibly intake, at least a plenum). I've been collecting lots of goodies while I was down and injured. Nothing too fancy or high tech, but it will get the job done and get this project started.

The Turbo. Precision 5431-CEA. It is essentially a T3/T4E 50 Trim with a .63 A/R Turbine, except that is has a billet compressor wheel with its own aerodynamics (CEA - Competition Engineering Aerodynamics) and dedicated turbine wheel and housing aerodynamics. That last fact means I can't upgrade to a .82 A/R turbine unless they offer one, which I wish they would because it would be more ideal for the 18+psi I want to run. On a 2.6 it will run out of breath at 24psi and 7000rpm, but I expect to hit 18psi by around 3000rpm, so it should be one heck of a kick in the pants. It is rated at 500hp, but conservatively (seen a couple people hit near 500 at the wheels).
Image
Image

And the stuff to make it work on the hot side of things. I just need a head flange made. SCH-30 304 Stainless steel tubing.
Image

My Treadstone TR11 intercooler, rated efficient to 560hp. Bar and plate, inlet flow divider, and excellent internal fin density.
Image
Image

Ill try and keep the pictures down. Fuel system is also ready to go. Walbro GSS341H 255lph pump, Delphi 86lb/hr injectors, and an Aeromotive FPR with gauge.
Image

My AMC Casting head is currently 400 miles away with a friend that does engine machining getting a complete port and polish, smoothed bowls, new guides, 5 angle valve grind, done. Since the work is mostly free it is being done on his spare time, but its a good thing I am not really in a hurry lol.
Image

And the rest of these goodies fitted as well. Eventually I will get the cam grind I want on order, but I keep putting it off for other things.

Image

Anyway, other things not pictured include the wastegate, and blow off valve, both Synapse synchronic pieces, some various aluminum bends for the intake piping, and the Megasquirt 3 sitting in a box in my closet waiting to be assembled.

The list of parts I still need is pretty good in size, but I almost have enough to get it together and setup to run. Then I can tear it down and start the build, get the clutch on order, and various other slightly important bits (Dana 44 axle sitting at buddies house to be shortened and 3.54 gears installed).
1988 Isuzu Impulse Turbo.
2005 Ford Crown Victoria LX

RIP 1989 Impulse Turbo, aka "Rakete"

User avatar
eyecon
God member
God member
Posts: 790
Joined: Sun Dec 12, 2010 9:53 pm

Post by eyecon » Wed Aug 15, 2012 4:01 pm

Good to hear from you again. I knew about your back issue on the 'zone, but it's good to see you're back (pun intended) on track. I'll be paying closer attention to your project because I'll be undertaking a similar route with my own 2.6 conversion but running on E85 fuel. You don't mention what type of pistons or rods you'll be using so I'm assuming you are running standard ones, but would standard ones be the reason why your aiming for 500hp? How much power do you think the MUA box can handle? Are those boxes available in Oz too? Great work so far and please keep us posted.
Dennis

IZU069
Power Moderator
Power Moderator
Posts: 963
Joined: Wed Sep 14, 2005 2:59 pm
Location: Melbourne (Orstralia)

Post by IZU069 » Wed Aug 15, 2012 5:41 pm

I think the MUA is the 4ZE1 (2.6L) Rodeo box; also in the MU. (I forget the MSA, MSB, MSG & MUA etc vintages & models.)


I suspect st'd Piazza 4ZC1-t pistons only handle about 180HP (same for the G200W) else maybe a bit more owing to the 180HP Jap Piazza.
IZU069 - ISUZU means a lot to me.

ImpulseRocket89
Senior Member
Senior Member
Posts: 194
Joined: Thu Dec 16, 2010 3:00 pm
Location: Omaha, NE USA
Contact:

Post by ImpulseRocket89 » Thu Aug 16, 2012 3:26 am

Double Post...
Last edited by ImpulseRocket89 on Thu Aug 16, 2012 4:29 am, edited 1 time in total.

ImpulseRocket89
Senior Member
Senior Member
Posts: 194
Joined: Thu Dec 16, 2010 3:00 pm
Location: Omaha, NE USA
Contact:

Post by ImpulseRocket89 » Thu Aug 16, 2012 4:24 am

eyecon wrote:Good to hear from you again. I knew about your back issue on the 'zone, but it's good to see you're back (pun intended) on track. I'll be paying closer attention to your project because I'll be undertaking a similar route with my own 2.6 conversion but running on E85 fuel. You don't mention what type of pistons or rods you'll be using so I'm assuming you are running standard ones, but would standard ones be the reason why your aiming for 500hp? How much power do you think the MUA box can handle? Are those boxes available in Oz too? Great work so far and please keep us posted.
Dennis
IZU069 wrote:I think the MUA is the 4ZE1 (2.6L) Rodeo box; also in the MU. (I forget the MSA, MSB, MSG & MUA etc vintages & models.)


I suspect st'd Piazza 4ZC1-t pistons only handle about 180HP (same for the G200W) else maybe a bit more owing to the 180HP Jap Piazza.
I actually plan to run E85 as well. Since I already have one walbro pump, I may just buy a second and run dual pumps in tank. Not that I need to with the current turbo, but since I purchased that Precision came out with a turbo much better suited to my power goals that would still be extremely responsive (5858-CEA)

No, I do not plan on running factory rods or pistons. I am holding off on buying the parts for the engine build as I have a lot of other things that need to come first to even warrant spending thousands on an engine build. My plan is to get the stock 2.6 as you see it to start and run with the EMS before I build it, that way I can avoid fuel washing the cylinders, and only have to do a bit of adjusting for the cam and port work.

As far as the type of pistons and rods, I haven't decided yet. I have seen that the company SPOOL makes a rod and piston package, but have not seen any reviews on them or know much about their quality myself. Pauter makes an off the shelf rod here and they are ridiculously strong, and I will most likely go with a set of custom JE pistons when I get to that point.

As far as the MUA box, I couldn't honestly tell you how much power it will hold, but if you see the internal differences in both the size of the gears and the shift forks (a weak spot for the smaller Impulse MSG) I know it will at least hold up better than the stock one.

The transmission itself can be found in most of the 2.6L trucks, however it would be worth it to verify before purchasing as certain years did come with T5's (Rodeo 2.6 in the mid 90's). In both RWD and 4wd form. My RWD version actually came from a V6 rodeo, but the front half of the transmission case is from an older trooper.

I am not the first person to do this trans swap into a JR Impulse, so most of the guess work was already done by another member of Isuzone. Borrowing his pictures I can show you the differences.

Case comparison side by side.
Image

Internal Differences Side by side.
Image

Notice the difference in the size of the shift forks.
Image

The real key issues to overcome with this trans swap are Speedometer correction, Much shorter first and second gears, and machine work to make the impulse shifter work/fit. One other tidbit of information that may help, when I was looking at trans rebuild kits, the sites listed this transmission code as the MSG-5F. According to JLEMOND, it is still an MUA box. Hopefully that helps.

Speedometer correction is actually easy, and I have done lots of math to figure out gear configurations to correct it.

The shorter gearing is probably the bigger issue, but still easily solved. The MUA-5 box has the following ratios: 1st - 3.767, 2nd - 2.248, 3rd - 1.404, 4th - 1.000, 5th - 0.809.

Compare that to the factory Turbo gearing and you can see the difference.
1st-3.431, 2nd-1.963, 3rd-1.364, 4th-1.00, 5th-0.775.

One thing to note is that the MUA gearing is fairly similar to the earlier JR non turbo transmission. If you plot both transmissions side by side at 7000rpm shift points, you will also notice that 1-2 on the MUA is 200rpm closer but 2-3 and 3-4 are a couple hundred rpm more widely spaced, while 4-5 is again a little more closely spaced.

In any case, the easiest way I have found to "correct" for the change in transmission gearing is to run a taller rear diff ratio, or increase the tire diameter on the drive wheels. A 3.73 diff or upping the tires 1" in diameter to 24.7 (which has the same effect) more or less corrects it back to what the factory trans/diff combination torque multiplication/mph ranges.

Speedometer correction would be fairly easy if you keep the factory rear diff ratio, as you just need to swap both the 5 tooth drive gear and 17 tooth driven gear out of the stock transmission into the MUA box. All later Isuzu 5spds had a 6 tooth drive gear inside the transmission.

I could make another post about all of this if you wanted.
1988 Isuzu Impulse Turbo.
2005 Ford Crown Victoria LX

RIP 1989 Impulse Turbo, aka "Rakete"

User avatar
eyecon
God member
God member
Posts: 790
Joined: Sun Dec 12, 2010 9:53 pm

Post by eyecon » Thu Aug 16, 2012 1:41 pm

A seperate thread on MUA conversion would be real handy. It might not come as a big surprise to you, but getting a hold of a second hand Impulse turbo transmission over here, let alone in good nik, is as rare as rocking horse shit (if not impossible). Some have turned to the more inferior Gemini boxes, but not without their own little set of mating issues. I managed to rebuild a spare turbo box that the original owner of my car had, so beyond that I'll have nothing. This issue will keep popping up down here so it would be nice to have a real solution, but only if you can spare the time.

ImpulseRocket89
Senior Member
Senior Member
Posts: 194
Joined: Thu Dec 16, 2010 3:00 pm
Location: Omaha, NE USA
Contact:

Post by ImpulseRocket89 » Thu Aug 16, 2012 2:10 pm

I will write something up to combine my own experience and the info from the member that first did the swap/write up on it.
1988 Isuzu Impulse Turbo.
2005 Ford Crown Victoria LX

RIP 1989 Impulse Turbo, aka "Rakete"

IZU069
Power Moderator
Power Moderator
Posts: 963
Joined: Wed Sep 14, 2005 2:59 pm
Location: Melbourne (Orstralia)

Post by IZU069 » Thu Aug 16, 2012 6:07 pm

23Dec15 - Corrected MUA's 5th ratio 0.089 to 0.809.
And I hope I mentioned somewhere that speedo gearing is independent of gear ratios. (Only diff ratio & rolling diameter effects speedo gearing.)
/end 23Dec15

This week I (re-)started comparisons of the MUA vs MSG, though I want it for a G200W (Isuzu 2L twincam) which - with merely an exhaust modification - produces around 400Nm torque. (For street use: 300Nm@2k & peak over 380Nm@3k RPM).
My former G200W was twisting the MSG output shafts!

My problem is it's DOHC which means the "traditional Isuzu" LH starter.
On MSGs it was simple enough to change the (RH starter-motor) bell housing with a bell from a DOHC (Gemini ZZR etc) or diesel (up to the C190).
But the MUA is different...


However, 4ZC1-t, 4ZD1 & 4ZE1 backing plates seem compatible with the MUA.
I think it's the same 6203 flywheel/spigot bearing - ie, 40x12x17mm - but that is also available with 16mm (ie, earlier Isuzus) & 1/2", 5/8", & 3/4" IDs.

Clutches might be interesting though I suspect the Piazza & pre-4ZE1 Rodeo/Jackaroo(Trooper) etc would be ok - just match appropriately to the engine's max torque. (MUA flywheels- ie, 4ZE1 etc - are 8 bolt, use a sunken clutch plate, and seem to craze anyhow...)
The MUA clutch spline (larger than MSG??) should be matchable to the "older" clutchplate. [ FYI - I intend to use an Exedy clutch. Good enough for my 1965 Isuzus, and still a "Quality" company. ]
And I'd expect the throwout arm to be ok (hydraulic push type) though maybe some spacing to ensure a near perpendicular normal position (a bit forward of perpendicular?).

The rear spline is a larger diameter. They are available with the same 1" universal joint that some Piazzas have (and pre-Gemini/i-Mark Isuzus), but otherwise a cut&shut prop shaft isn't IMO a big deal nor expense.

I think all the speedo take-off gears else carriers are compatible and I know of at least 16, 17 & 18 tooth versions.

Then there is the gearshift extension clearance...
(And maybe general bell & box to body clearances.)


FYI - the MUA gearbox ratios I have listed are:
- to 1991: 3.767, 2.314, 1.404, 1, 0.809 with Rev 3.883.
From 1992, 2nd changed to 2.248 (& reverse unknown).

Though not the 0.782 (occasional) MSG or 0.775 5th of the 180HP PIazza that I prefer, the MUA's 0.809 is much better than the more common 0.855 5th gearing.
Last edited by IZU069 on Wed Dec 23, 2015 8:06 am, edited 2 times in total.
IZU069 - ISUZU means a lot to me.

ImpulseRocket89
Senior Member
Senior Member
Posts: 194
Joined: Thu Dec 16, 2010 3:00 pm
Location: Omaha, NE USA
Contact:

Post by ImpulseRocket89 » Fri Aug 17, 2012 8:56 am

The backing plates between the 4Z motors are all interchangeable, at least with other 4Z motors. The only two differences between the one that came off of my 4ZE1 and the stock 4ZC1 were a matter of two sets of bolt holes.

The 4ZE1 plate from the 2.6 with the cast aluminum upper oil pans has a second set of holes on the lowest part of the bracket, though I am unsure what they were for as my engine came without a trans and they were unused for me to make an observation. They did not interfere in any way and could have been used, however.

The 4ZC1 plate also has a couple of small diameter tapped holes for a couple of M10 bolts to secure the lower access plate that sits right behind the stock Impulse/Piazza oil pan. From what I could tell, the 4ZE1 plate did not have this, and that is because the cast upper oil pan of the 4ZE1 does this job. This wouldn't be a very big deal as a couple of small holes and a quick tap could fix that problem as well.

Beyond those small differences, either plate could have been used.

As far as clutch choice, in your case I am unsure as I am not familiar with the G200 engines. In my case, I am simply using an entire Pickup/Trooper Flywheel, clutch, and throw out with the truck transmission. The larger diameter clutch will be a big help with holding power, it fits, and the stock 2.0 and 2.6 flywheels weigh pretty much the same.

The clutch spline is the same between My impulse box and the MUA out of the rodeo (which was a V6 too btw). Isuzu really didn't change these much over the years. I could just as easily run the 4zc1 flywheel and clutch setup.

As far as the rear spline being a larger diameter, that makes me wonder why my stock driveshaft fits perfectly. If it was larger, I would expect there to be a problem? I won't be using the stock driveshaft or yokes anyway by the time I am done as I am having a custom driveshaft made to use a truck front yoke so I can purchase U-joints at any parts store, and with a new rear axle I will have to change to a different style at the rear flange.

As far as the speedo gears, there are 2 drive gears and 6 driven gears.

The drive gears are 5 and 6 (6 is the most common past 1990).

The driven gears that I know of are 16, 17, 18, 20, 21, and I am not sure on the last one. It was either 19 or 22.... lol

As far as trans body clearance. The MUA box fits in the trans tunnel of the Piazza/Impulse, though it is snug. Gearshift, if machined down as seen in the write up I did on this exact swap, which you can freely add what you know btw, then it fits fine. I am waiting to see how Bugle's home-built shifter fits to be able to know if that fits as well.
1988 Isuzu Impulse Turbo.
2005 Ford Crown Victoria LX

RIP 1989 Impulse Turbo, aka "Rakete"

IZU069
Power Moderator
Power Moderator
Posts: 963
Joined: Wed Sep 14, 2005 2:59 pm
Location: Melbourne (Orstralia)

Post by IZU069 » Fri Aug 17, 2012 7:11 pm

That's great info. Some real good detail.

I may be wrong on the splines - I was working from memory.
But today I did confirm the input fine spline as 1" x 24. (That's from a twincam, but should be the same as most (non-early) Gemini's.
I have yet to (re-!!)measure my 4ZE1 box.


I was going to complain ( :yawinkle: :yawinkle: ) about your referral to a G200. It's a G200W - ie, the Isuzu twincam (also G161W & G180W) as opposed to the common GM-Isuzu SOHC Z series (G161Z, G180Z, G200Z).
But the G-series is a distraction from your 4Z series (other than the common main & big-end bearings etc as shared by all G- & 4Z-series engines). Besides, your excellent posts make even a jest dig seem pathetic.

FYI - the other G's are the Jap Isuzu SOHC - ie, G161S & G180S (the G180S is the same block as the G200W twincam), and the older OHV pushrod engines which I call the U-series (for Under-head cam) - ie, G150U & G161U and the older 3 main-bearing versions - the G160U and (again...) G150U.

The Z-series is essentially totally different to the rest of the G-series (other than main & big end bearings plus some conrods and pistons), however they share very similar - and I think interchangeable with maybe minor mods - inlet & exhaust manifolds.
Oh - I forgot - valve stem seals should all be the same, and maybe some valve guides & valves. And all manuals use the 6203 crank-end to gearbox (spigot) bearing - 40mmOD x 12mm - but in either 16mm or 17mm ID versions (also available with 1/2", 5/8: & 3/4" IDs).


Thanks again for your info.

And if you ever find a left-side startermotor bell for the MUA boxes, please let me know.
IZU069 - ISUZU means a lot to me.

ImpulseRocket89
Senior Member
Senior Member
Posts: 194
Joined: Thu Dec 16, 2010 3:00 pm
Location: Omaha, NE USA
Contact:

Post by ImpulseRocket89 » Sat Aug 18, 2012 5:04 am

IZU069 wrote:
I may be wrong on the splines - I was working from memory.
But today I did confirm the input fine spline as 1" x 24. (That's from a twincam, but should be the same as most (non-early) Gemini's.
I have yet to (re-!!)measure my 4ZE1 box.

Both of my stock MSG and MUA input shafts are also 1" x 24 spline.

The only real differences you find is with the flywheel and clutches themselves. As long as you use the clutch appropriate to the engine that the flywheel came from, then it should work with whichever transmission you use.

Thanks for the extra bit of information on the U and G engines. Not sure if it will come in handy for me, but it never hurts to know.
1988 Isuzu Impulse Turbo.
2005 Ford Crown Victoria LX

RIP 1989 Impulse Turbo, aka "Rakete"

IZU069
Power Moderator
Power Moderator
Posts: 963
Joined: Wed Sep 14, 2005 2:59 pm
Location: Melbourne (Orstralia)

Post by IZU069 » Sat Aug 18, 2012 6:51 pm

Yeah - the old G-series (GU, GS, GW, GZ) is probably useless to you. (It's handy for GW twincam owners and GU Bellett/Florian/Wasp etc (1964-1973 Isuzu) owners.
But for 4Z-ers, other than the bearings and GZ port similarities - and maybe the GZ gearboxes, I can't see much relevance. Even the GZ distributor (a godsend for Bellett etc & GW twincam owners) is useless as it spins in the opposite direction to the 4Z. And it's the 4ZE1 locked optical dizzy that is sought for aftermarket & OEM I-TEC EFIs (though the twincam G200W Piazza has the same dual-optical guts as the Jackaroo/Trooper 4ZE1 distributor).


I checked my MUA(?) gearbox which is from a 4ZE1 TFR Rodeo.
The clutch is the same 1" x 24 as with earlier "modern" gearboxes and has the later 17mmID spigot bearing (ie, 17mm input shaft).

But the prop/output shaft is ~27.5mm (1-1/12"??) with 27 splines.
I was wondering if I was confusing my aforementioned "bigger" fine spline props with my Piazza 4ZC1-t auto transmissions though now I realise it was that whatever big Isuzu spline was the same as found on some automatic Commodores (GM/GMH; maybe VL or VN???).
(It's that larger output I want to prevent my G200W twisting output shafts.)


Incidentally, I suspect my TFR gearshift extension is the same as Bugle's in your MUA-5 Transmission Swap thread.
It's an alloy "top" but the extension is bolted-on steel with the stick-ball centered about 212mm rearward from the nearest (rearside) sandwich/gear-carrier plate.
I was tempted to post the latter in that thread - and praise Bugle's fantastic stick extension! - but here means one less reply. (Feel free to copy&paste into that thread...)


And sorry for my bum-steers. I often work from age-old memories that have remained stagnant. (Forums relevant to my vehicles seem to prefer to reinvent everything!) And I have yet to recover "recent" document updates (ie, updates since ~2,000CE).

But you guys IMO are fantastic!
IZU069 - ISUZU means a lot to me.

ImpulseRocket89
Senior Member
Senior Member
Posts: 194
Joined: Thu Dec 16, 2010 3:00 pm
Location: Omaha, NE USA
Contact:

Post by ImpulseRocket89 » Sun Aug 19, 2012 2:59 am

I must be out of date on the 4ZE1 Optical distributors ( never knew there was one ), but I do know that the distributor from my 4ZC1-T is also an optical style unit and has been used with a Megasquirt 2 EFI system. That is why I retained the 4ZC1-T distributor on my ZE swap. Is there a difference between this one and the ZE optical?

So is the 17mm ID input shaft better compared to the box you are using?

The bigger outputs then would be from the autos? It would make sense to me as auto transmissions do tend to have a greater torque multiplication thanks to the converter. It may just be a GM standard size for that trans used as well, as I know the Automatics in most Isuzu vehicles were simply GM boxes.

I will copy and paste your praise for you if you like lol. I don't really care about one more post on the thread. You have a lot of knowledge to bring to the table, and I like having more points of view on this kind of work.

As far as the bum-steering. Don't worry about it. I tend to do the same thing as I commit most of this stuff to memory. I need to make some kind of a database with all of the information gathered and store it away...
1988 Isuzu Impulse Turbo.
2005 Ford Crown Victoria LX

RIP 1989 Impulse Turbo, aka "Rakete"

IZU069
Power Moderator
Power Moderator
Posts: 963
Joined: Wed Sep 14, 2005 2:59 pm
Location: Melbourne (Orstralia)

Post by IZU069 » Sun Aug 19, 2012 10:25 am

Aha! If your 4ZC!-t came standard with an optical dizzy, it must've had the I-TEC ECU.
For some reason, the Australian 4ZC1-t came with a typical mechanical distributor - a governor & vacuum advance (yet the ignitor was linked to the knock sensor or ECU).
I've always been meaning to find out if other 4ZC1-t Piazzas had the optical.
As to why we recalcitrated to a mechanical dizzy - and a JECs copy of the Bosch Jetronic ECU - AFAIK the last valid conclusion is that GMH "couldn't handle" the all-electronic I-ITEC. (That must have added a reasonable cost to the Aussie Piazzas LOL.)

I'm reasonably sure the 4ZE1 & 4ZC1 (& 4ZD1) dizzies are physically interchangeable. (The 4ZB1 isn't - it has a different hole or location. My hero RodeoBob wrote about that somewhere - maybe on here, else holdengemini or ozgemini.)


As to their guts, the G200W DOHC Piazzas also had ITEC with an optical dizzy. (That was in 1980, and we got our mech-dizzy Piazzas SIX years later!).
Though the G200W's optical sensor module is older and has visible components, it is mechanically interchangeable with the 4ZE1 Jackaroo/Trooper module. (But NOT the Rodeo. The Rodeo interface connector is a 4x1 connector that exits out the side. The Jackaroo & G200W Piazza have a 2x2 spade connector that exits out the dizzy's bottom.)

Electrically I see no issues. The electronics merely pulse the slots and should use the same switching (ie, open collector or 0V/ground/earth/chassis switched - ie, "low" when pulsed).

Both discs have the typical rings of 4 & 360 slots. Any alignment problem would be restricted to its mounting position, but distributor rotation should compensate for that, else remount the disc. (I have samples of both, but they are elsewhere at the moment.)

[ FYI - IMO the 360 slots is why that dual-row optical system is so good for other ECUs. For those that require 1 & 4 slots, just fill in 359 slots (with liquid paper etc). For other combinations (4-6, 4-12 etc, 2-1, 1-12, etc), fill all but the required slots. And since its locked, rotational direction does not matter. ]
(BTW - good to hear of another Megasquirt. The old DIY-EFI has gone a long way - though I still think they don't have self tuning?)

So distributor-wise, you shouldn't have any problems.


[ FYI - the RG dizzy: Otherwise.... I can't recall my "RZ" diizzy in a 4Z outcome. The RG dizzy is a (common) G-Z engine dizzy (from our Geminis, and older Rodeos & Jackaroos). Its points and upper rotor are replaced with the reluctor sensor on its bearing carrier, and upper rotor from the early FWD RB Geminis. It can be locked for ECUs and reluctor-sensor output extended. For spark, the RB's internal ignitor can be mounted internally.
The RG (G-Z) dizzy is easily modified to fit ANY G-series engine - ie, the DOHC GWs, OHV GUs, and Jap SOHC GSs. Hence "we" with inferior and rare GU & GW distributors have a readily obtainable distributor. GZ owners get cheap electronic ignition. The RB's reluctor is the newer robust & superior single-piece system (not the weaker multi-piece & multi-pole systems of the GW, Nissan N13, VL Commodore, JE Camira, etc).
The RB ignitor is also used in other Jap vehicles and with its common "blue"oil-filed Nippon-Denso ignition coil is a ripper. (It operates well below 6V.) Newer E-coils can also be used. Current limiting does not seem to be an issue. I have used Bosch MEC-717 etc coils which have a mere 0.4 Ohm primary resistance - ie, 4x the current of standard RB etc ignition coils.) ]


The 17mm input shaft per se shouldn't make much difference. That is merely the crank-shaft locator and shouldn't carry any load. However it should signify a generally stronger box.
Early Isuzu boxes (MSA, MSG etc) had weaker 2nd gears - the most common source of synchro & gear wear or failure.
The MUA (TFR etc) boxes fattened their 2nd gears (that info from RodeoBob).
And the later boxes are stronger - as shown by bigger shaft diameters etc in your pics.

Interesting that my TFR box has a larger output spline. However, even the smaller spline has AFAIK a fatter output shaft to the spline. Though the smaller spline will still be twisted by my (hi-torque modified) G200W, at least the fore-shaft has less chance of breaking.


Thanks for understanding those bottom-cavines (bum-steers). I try to add AFAIK & I thinks when uncertain. But of course, there are times when I'm wrong. Sometimes bad memory. Sometimes finding out about alternatives that I never struck.

You might find my digressions and ramblings a bigger pain LOL!
[eg - the RG dizzy stuff - especially since optical 4ZE1 dizzies should be relatively easy to obtain. At $35, they are worth grabbing whenever a (Jackaroo; else Rodeo) 4ZE1 comes into our local "Pick A Part" wreckers. But as a final fallback, I could resurrect my 1988 flywheel ignition. These days probably using a $3 PICAXE 08, and installed by fitting 2 sensors to the starter motor (the 2nd being redundant - the system monitors both and alerts to intermittent operation) and filing the edge off one end of a flywheel ring-gear tooth.]
But my ramblings are also for the benefit of other Isuzuans as well as for "our" backup or workaround methods.


Incidentally, my "MUA" box is from a TFR (4ZE1) Rodeo (2WD of course!), though I also have a complete 4ZE1 Jackaroo (all are 4WD).
In my outdated engine & gearbox table, I have the MUA as coming from the Isuzu MU (pre- & post-1992 versions).
The MU became the Frontera and some are 4ZE1 (I think). I might look further in to them. (eg, see pick-a-part - parts-recovery, select Isuzu and see a 1991 Frontera at the moment. Normally Isuzus are listed under Holden - ie, Shuttle, Jackaroo, Rodeo, and Gemini (with the RWD "T-series" with GZ engines being pre-1985(?) and FWD RB being post-1985 [Gemini knowledgeable people may correct me]. )

I've intended to hit my shed to measure gearboxes & engines etc and update my docs. That's AFTER I tidy up my house.
I've been tidying now for a few years with little success. I might be tempted to review my priorities. Besides, summer is coming - I should get out more.

Oh dear, another short reply...
IZU069 - ISUZU means a lot to me.

Post Reply