1Z MTDI recipe request and gearing questions

[Christopher Schimke]

So...considering doing a 1Z MTDI conversion for my Syncro.

Gearing - What should I shoot for as my cruising RPM? 70 mph is tops for me. In fact, I prefer to drive 65 since the van just feels more comfortable at that speed. I have read that most people try to achieve a 3000 RPM cruising RPM for a TDI in a T3. Is that about right or is there a better "optimum" cruising RPM? And just so that you know, I plan to keep my tires in the 29"-29.5" range and keep my 5:43 R&P. This means that I will have to play with my 1-2-3-4 gearing to achieve the desired driveability. My thoughts are that with the 29"-29.5" tall tires, 5:43 R&P combined with the TDI low-end torque, it should create a great crawling rig. I would just have to tune the gearbox for the on-road manners.

Ground clearance and deck clearance - With a 1Z MTDI, are there any clearance benefits with either of the mounting positions (laid down or upright)? I'm not opposed to building a custom intake manifold or oil pan of I need to, but what makes the most sense in an effort to achieve the best clearance for both the ground clearance and the deck clearance and what will it take to achieve that?

So my goals are proper gearing, maximum ground and deck clearance and the simplest installation as possible (hence the mechanical pump). I'm not afraid to fabricate bits to achieve my goals, so any insight into what it will take to get there would be much appreciated.
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[?Waldo?]

Do you already have the engine. If you do not already have the engine, the AHU is a slightly better option as it has stronger rods. It's not a huge difference and the 1Z is a fine engine to use if you already have it.

The AHU or 1Z are both the same block style as the 1.6 (and AAZ) engines and so, the easiest route AND the best ground clearance will come from an install using the stock diesel vanagon mounting bits, bell housing, oil pan, etc... That will result in maximum ground clearance and no intrusion above the engine lid.

The TDI won't have any difficulty cruising at 3500 or even a bit higher. The only downsides are noise and a bit of a drop in fuel economy. If your preference is to cruise at 65, then I would gear 3,000 @ 65MPH. With that gearing you will be able to cruise at 70-75 if need be and will still be high enough in the rpms @ 65 to develop enough HP for cruising with a 'cushion'.

[Waldi]

You are ok with 225/75-16 or 205/80-16 tires and a gearbox 5,43x0,78.
You can also go taler changing the 4th to 0,74. But for my feeling the step from 3rd would be too high.


On the pics you can see the best solution in my opinion for a mTDI.

[fairweather]

In my experience the most important issue was the gaps in the gearing, keep them as small as possible. I'd give up some top speed to keep them tight. Esp. if you are going to be cruising in the mtns. My biggest issue with my mTDI syncro was getting stuck in 2nd gear up the passes because it couldn't make the jump, I can't remember what I had but I believe it was one step taller for both 3 and 4 with 30x9.5 tires and 4.86 rp.

I would try to drive Hans' van, sounds like he has something he is happy with.

I think maybe you should pioneer the first AWD, 5spd, TDI syncro

And I would def just install a AWIC right from the start.

[?Waldo?]

[MarkWard]

Christopher, I have a later TDI mounted at 50 degrees with a few custom bits in my 2wd camper. Running a 4.14 ring and pinion with a .77 4th and have no problem with hills and am able to cruise about 2900 at 70 mph. That is way taller than you are talking about going.

I also am in the beginning stages of a syncro conversion. I'd like to use a diesel bellhousing again, but I understand the starter location of the diesel bellhousing interferes with the syncro fuel tank. There is a diesel syncro tank and I have a WTB add for one. No luck so far.

So that leaves 50 degrees with an adapter on a WBX bellhousing or a SA bellhousing upright. Upright you don't need to deal with a custom oil pan if you went with one of the later style TDI's, so that is a plus, but at 50 degrees, you might not need to deal with the engine cover on a syncro since the engine does sit lower. Fortunately I am doing other parts of the project right now and can decide later about the engine install.

I understand that some have modified the syncro gasser tank to work with the diesel starter, but I imagine it involves a heat gun and if you got it all to fit, it is unlikely you could replace the starter on the road if it died.

For my syncro, I will be going with the stock 4.86 and probably a .75 4th. I think with the granny gear, it will be much better than my 2wd crawling uphill and still get down the road getting decent mpg. No rock crawling for us. mark
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[?Waldo?]

My 2WD 15° ALH sticks up above the engine lid this much:

You'd be darn close to or possibly above the top of the engine lid in a syncro. You'd also lose an inch or two of ground clearance.

I have not changed the starter on a TDI syncro but have heard others mention that with the stock diesel syncro fuel tank starter removal is much easier than on a stock gas syncro.

[hans j]

After doing mine, I have a bunch of thoughts on what I will do next time. For me I prefer the eTDI because that's what I know. Sure it's a bit more work but I don't mind. I'm in between doing a mTDI on my AHU 2wd because I don't have the ECU or wiring yet. But, I happen to LOVE cruise control and it works with the eTDI ECU and factory cruise control switch.

I think for my next ALH conversion, I want to use the FAS adapter plate and probably make my own 50* oil pan out of the factory steel 06A pan. Although I am not minding the modified engine lid and I can shorten it even more for more padding. We also sleep on a 2" memory foam mattress

I can't comment on your gearing unless you make a comparison chart with your tires and r&p. I am running 27.8" BFG, 4.86 r&p and the 1.14 3rd and 0.73 4th. I like it. It has enough power to pull the 2-3 shift going up hill 'most' of the time. I have not installed an intercooler yet (2 years on the conversion?) but I do have Sprint 520 nozzles (Euro 110?).

My 2wd AHU conversion is using factory diesel vanagon parts and likely a G60 flywheel with the VR6 PP and vanagon disc. Process is slow going though due to money going towards suspension
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1986 Canadian Syncro Westy TDI - 1989 Syncro Single Cab - 2001 Audi S4 - 1981 VW Caddy ABA - 1980 VW Caddy EV - 1973 VW T-181

[hans j]

[?Waldo?]

You don't gain anything with the eTDI over the mTDI except data-logging capability if you are running a wastegated turbo. It took me LESS combined time to completely rebuild a Land Rover 300TDI injection pump for my ALH build AND make my engine harness (for gauges and glow plugs) than it took Surfcamper to install his vanagon specific Fast Forward pre-fabbed wiring harness. I love my eTDI Jetta, but it does nothing better than either of my mTDIs and has a whole slew of additional failure modes that will result in either limp or no-run. There is no operational condition where my eTDI runs better than either of my mTDIs and I've run from sea level to 10,000' of elevation and ambient temps from over 100°F to below 0°F.

I suppose ECU cruise is a perk, but an aftermarket system is certainly far less cost or labor to install than the additional effort required to install or the cost of the parts for the entire engine management. I would also much rather remove the potential failure modes of the electronic engine management than have a 'free' cruise control.

I love electronics and would enjoy doing an eTDI swap if it gained me anything other than more issues on the road.

[Waldi]

[quote="Andrew A. Libby"]

[Jon_slider]

I agree 70mph @3000rpm is a reasonable ballpark, but you will get a bit more acceleration, and lower EGT, if you go closer to 68mph@3000rpm

1. with a 29.3" diameter BFG AT Ko 225x75x16, and a 5.43 ring and pinion, I recommend using a .70 4th, your speed at 3000rpm will be 67mph. I would use a 1.08 3rd with that 4th.
The shift gap from 2nd to 3rd will be 11% wider than stock
The shift gap from 3rd to 4th will be 6% wider than stock
However, Im not sure your motor can handle this configuration, it may be too tall for your horsepower.

2. with a 29.3" diameter BFG AT Ko 225x75x16, and a 5.43 ring and pinion
IF you use a .70 4th, your speed at 3000rpm will be 67mph (and 78mph@3500rpm). I would use a 1.08 3rd with that 4th.
IF you also change 2nd to a 1.88
The shift gap from 1st to 2nd will be 7% wider than stock
The shift gap from 2nd to 3rd will be 3% wider than stock
The shift gap from 3rd to 4th will be 6% wider than stock
This configuration makes 2nd much more useful on pavement, but a bit harder to shift from 1st to 2nd going uphill offroad.

3. with a 29.3" diameter BFG AT Ko 225x75x16, and a 5.43 ring and pinion
IF you use a .77 4th, your speed at 3000rpm will be 61mph (and 71mph@3500rpm). I would use a 1.14 3rd with that 4th.
The shift gap from 2nd to 3rd will be 6% wider than stock
The shift gap from 3rd to 4th will be 3% wider than stock
imho, this configuration is too short geared in 4th

4. with a 29.3" diameter BFG AT Ko 225x75x16, and a 5.43 ring and pinion
IF you use a .73 4th, your speed at 3000rpm will be 64mph (and 75mph@3500rpm). I would use a 1.14 3rd with that 4th.
The shift gap from 2nd to 3rd will be 6% wider than stock
The shift gap from 3rd to 4th will be 7% wider than stock
This may be the ideal configuration for your motor's horsepower.

===
regarding shift gaps, the 11% gap of configuration #1 is slightly challenging. I currently run that setup with a stock 2nd, which gives me an offroad advantage going from 1st to 2nd. However, on pavement my 2nd gear is shorter than I would like. I run a 5.43 ring and pinion, and a 30.5" tire. For your tire, I would prioritize the 1.88 2nd, as my tire and gearing is already taller than yours, and I already find 2nd too short on pavement.

If I was running your tire size, I would use configuration #2. However, I have no experience with a 1Z, whose spec is 90 hp. My Tdi has 140 hp. So if someone with 1z experience says to use configuration #4, I yield to their experience.

imo a 6-7% wider than stock shift gap is pretty comfortable to live with.
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[Waldi]

The gearing depends a lot of personal taste and the van shape and weight.
And not least from the money.
You never can say that one gearing is perfect for all.

Edit:

For my shown engine in a 2wd i need only to heat the cover and smash with a hammer 1cm up. Than some polyester and painting - ready.

[?Waldo?]

[Waldi]

The spring from 2 to 3rd will be 6% only if there is a 1,88 2nd.
If 2.06 you can forget it. Or pay.

[?Waldo?]

[Jon_slider]

[fairweather]

I like #2, I had AA install that 1.88 2nd and love it, pricy little shaft tho. #4 if you don't want to spring for that.

[Waldi]

The step from 2,06 to original 3rd is anyway big.
I would not like to have it bigger.

I use 3 sets of different tire sizes with my 4,85x0,78 100hp AAZ syncro.

205/65-16 for pulling a heavy trailer.
215/75-15 hankook mt for offroad
205/80-16 AT for long trips

Because it is like i say, a perfect ratio for all does not exist.
I would change r+p before changing 3-4 with longer steps.

[Jon_slider]