LT 2.4 Petrol engine to 2.5 TDI conversion |
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cnycl
Groupie Joined: 22 Dec 09 Location: Istanbul/Turkey Status: Offline Points: 118 |
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Posted: 05 Dec 10 at 22:06 |
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Finally our TDI conversion started progressing and I'll post it here step by step as my syncro friends (www.syncroturk.org) complete each level (wiring, sump modification, exhaust fitment, electrics, engine installation etc.). I hope this may help others deciding the same upgrade since we know this has been done before but there's no clear guide on how to do it properly.
As usual, disclaimer conditions apply; this conversion is something we're doing on our own risk and we can't guarantee it will function properly on your vehicle or you can get legal permits for road use and it is not approved by the vehicle manufacturer. Therefore if you're thinking of doing the same conversion, don't forget you'll be doing it on your own risk, knowing the conditions mentioned above.
Anyway the vehicle we're working on is an '88 VW LT 31 with 2.4l carbed petrol engine mated to a 5 speed gearbox. Donor vehicle is an Audi A6 with 5 pot 2.5l TDI engine.
This is the beginning, engine and wiring loom as they come from the breakers.
Wiring loom sorted and simplified.
2.4l turbo diesel LT sump and TDI sump side by side. Engine bracket on LT requires LT specific sump to be used on TDI engine since TDI sump is much deeper than the LT one. Bolt pattern of these sumps are very very smiliar except 2.4l sump is a little longer (1 pot) than 2.5 TDI.
Long portion to be cut is marked as below
And there it goes
Cut but unwelded part on the engine. Since depth is not uniform along the sump minor leveling is required before welding.
LT sump on TDI engine. We did not modifiy the oil pick up pipe yet.
Another angle
More to come as the project keeps going...
Edited by cnycl - 06 Dec 10 at 10:05 |
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GT500
Groupie Joined: 02 Jul 09 Location: leeds Status: Offline Points: 145 |
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Great stuff!!!!
Just stripping my A6 at the mo! Try to catch up with ya! Wiring, is a pain. been stripping my loom back (its still in the car) testing as I go. Seems the immobiliser is a bit cleverer than I thought. Trying to find the current flow diagram for it... Anyway it did run lovley now it its stopped by the dammed immo. I have vagcom and all you get is "start blocked" Going to get the engine out today and sort it when its in the van. ANy chance we can have a detailed few pics of your loom please? Rob |
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Rob... The only LT on 18" wheels.
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Bo_Hedin
Groupie Joined: 30 Jun 09 Location: Cranleigh Status: Offline Points: 132 |
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Wow, Just what we've all been waiting to see.
Good luck! Starting to think along these lines as I can't even get an oil filter for my engine anymore....and that extra performance would be great. |
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VW LT28 2.4D Westfalia Sven Hedin 1978
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Canada LT28
Vanorak Joined: 03 Jan 10 Location: Toronto Status: Offline Points: 1632 |
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Excellent work Cnycl,
I've got my 99 TDI 1.9 and am looking to go with the mech TDI pump to do away with the electronics. Looks like you will be done long before I actually get started. Mike |
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mechano
Not Quite Newbie Joined: 15 Jan 10 Location: Ankara / Turkey Status: Offline Points: 37 |
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Hi All,
This is Eren, I am actually a syncronaut and not an LT fan, but as Cnycl stated this conversion is done in my garage and mainly by me. So here is what we did this weekend with Can (cnycl): Took out the engine from the LT (what a pain in the a..) also the transmission. with both engines out, we were able to see what will or will not fit. -The bellhousing pattern is same as TDI as expected, I am planning to use the TDI flywheel, pressure plate & starter, as the TDI has much more torque. -TDI has a 240mm clutch whereas the 6cyl petrol has 228mm, TDI also has a dual-mass flywheel. -TDI friction disc has the same spline as the 6cyl petrol so it can be used -The pilot bearing in the TDI flywheel is smaller and 6cyl petrol engine has a bearing pushed into the crankshaft with a bigger inside diameter. I was able to push out the bearing of the TDI flywheel, so installing a new bearing in to the TDI crankshaft will solve the problem. -However there is problem: When assembled, the TDI pressure plate will sit approximately 1cm out than the 6cyl petrol one. This means that the throw-out bearing will be pushed 1cm in to the transmission. I guess the clutch adjustment will not be enough to solve this problem, so I am planning to modify the lever of the clutch or may be its fulcrum or use another pressure plate... Looking at the other sides of engines: -The engine mounts are completely different, 6cyl ones wont fit to TDI, both sides need to be build from scratch. -The crankshaft pulley also the visco fan of the 6cyl petrol will fit to TDI engine. -The LT power steering pump fits to TDI engine with very little grinding of its bracket. -The alternator will not fit as it simply hits the turbo, has to be relocated and looks like a bit hard to find a new place... As for the wiring I have not finished it yet, as Can (cnycl) sent the pictures I have simplified it but I have to take out the wiring of the pedals from the main harness. I am not worried about the wiring as I have converted my syncro to TDI before (1.9 AFN engine) A syncro friend I met in Germany in syncro25yrs event sent the wiring diagram of this engine, here is the link: http://www.audifans.net/ftopict-33526-aat.html+wiring Here we are pulling the engine-less LT away from the garage with my syncro, we had some nice snow this weekend here in Ankara / Turkey. I will be working on this conversion only weekends, so this will take some loooong time.. we'll see.. Eren B. Edited by mechano - 16 Jan 11 at 21:49 |
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Canada LT28
Vanorak Joined: 03 Jan 10 Location: Toronto Status: Offline Points: 1632 |
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Can you tell how the shift linkage for the tranny looks? Will it be an easy changeover to the stock LT shifter? Also, do you think a 1.9 tdi would also need the sump cut and re-welded?
Good work..... Mike |
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cnycl
Groupie Joined: 22 Dec 09 Location: Istanbul/Turkey Status: Offline Points: 118 |
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Hi Mike,
Since we're using the original tranny, stock LT shifter configuration will remain intact. So no worries there. Regarding 1.9 tdi sump, Mechano knows it better. He's done a similar engine conversion (2.0l petrol to 1.9 tdi) on his syncro before. But as far as I know/saw desing of the front axle of LT will probably require any other sump to be modified somehow. To keep the engine hump low inside the van, VW engineers stuck everything really close in the engine department. Good luck |
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Canada LT28
Vanorak Joined: 03 Jan 10 Location: Toronto Status: Offline Points: 1632 |
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You are changing out a gasser for the TDI and I think the tranny has the same gear ratios as the diesel LT. Do you know what the difference in RPM is for the two engines. There was a Volvo sitting for a few years behind my shop and just when I was going to ask the owner for it, he towed it away. Gear ratios would have been nice but now I must find something else. Is the top end RPM better on the TDI over the 6 pot?
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cnycl
Groupie Joined: 22 Dec 09 Location: Istanbul/Turkey Status: Offline Points: 118 |
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Gear ratios of the current gearbox will not probably match TDI engine but we swapped wheels and tyres from 14"/195-80 to 16"/205-80 and this may help a little bit.
In the long run I think it's better to use a different rear axle than playing with the gear box. Especially an axle with a diff lock.
Calculations for rear axles with different ratios and wheel sizes are given below (these are 5th gear calculations).
If you're staying in 100-120 km/h band at 3000 rpm in 5th gear, TDI engine has more than enough pull to handle other gears and long distance rides will probably be much more comfortable.
BTW your stock axle gear ratio may not be 40:9 and transmission ratios may differ please take this into account when making modifications.
Edited by cnycl - 14 Dec 10 at 07:45 |
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Canada LT28
Vanorak Joined: 03 Jan 10 Location: Toronto Status: Offline Points: 1632 |
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Pretty informative. I understand the stock numbers but is the "Dana" from a TDI truck? I am pretty sure I have the stock ratios with the 40:1 diff as I need a strong tailwind and a good down hill to get past 110km/h. I did change to 175/16 wheels (thread somewhere on here) which dropped the rpm a bit but it's not a huge improvement.
If it is available I may ship one over, or am I nuts. |
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cnycl
Groupie Joined: 22 Dec 09 Location: Istanbul/Turkey Status: Offline Points: 118 |
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Dana axle is not from a TDI engine.
They're stock axles of most U.S. branded 4x4's, pick up trucks etc.
We're planning to get a set from the breakers to convert 4x2 LT into 4x4 but thats another story.
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mechano
Not Quite Newbie Joined: 15 Jan 10 Location: Ankara / Turkey Status: Offline Points: 37 |
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Hi, I guess you need to use an LT sump and cut-weld like I did as any other sump will hit the front-end. For a 1,9 swap you need use an adapter plate between the engine and tranny as the 1,9 4cyl bolt pattern is not the same as the 5 or 6cyl ones. When you use an adapter plate the engine will move forward which may cause even the LT sump to hit the front end, have to check. Eren B.
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Canada LT28
Vanorak Joined: 03 Jan 10 Location: Toronto Status: Offline Points: 1632 |
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Thanks Eren,
Have you already put a 1.9 in an LT? I won't get to this before summer but it is always good to know what i am up against. Keep up the good work.... Mike |
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mechano
Not Quite Newbie Joined: 15 Jan 10 Location: Ankara / Turkey Status: Offline Points: 37 |
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Hi, No. I did convert my T3 syncro from wasser-boxer to 16 valve petrol and then to 1,9 TDI which also involved to build an adapter-plate and flywheel to covert boxer bolt pattern to inline 4. Definitely a 5cyl Diesel conversion for LT is easier than a 4cyl, as you won't need an adapter-plate. Thanks. Eren B.
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mechano
Not Quite Newbie Joined: 15 Jan 10 Location: Ankara / Turkey Status: Offline Points: 37 |
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Hi All, It's been a while, it was Christmas holiday, also I was busy at work (moved to another office etc.) Anyway, this weekend I checked engine mounts, I decided to use and modify the LT aluminium mounts. On either side only one hole location is same on TDI engine as the petrol. Turbo Side: This is how the 2,5 TDI (AAT code) engine looks like on turbo side This is how the LT petrol engine looks like, same side The LT oil filter adapter has to be used on TDI engine as If you try to use the TDI's original, the filter will simply hit the engine cross member (front-end). This is how it looked like when I have put the LT filter adapter and LT engine mount on TDI engine: I had to remove the turbo oil return pipe as it would hit the filter bracket. I will make a new pipe to oil sump. I had to grind the mount to clear the turbo itself, also as you can see only one bolt is holding the mount on engine, but as this hole is at correct location so the engine mount location is correct here. Here you can see the the area that I have grind to clear the turbo: I decided to use the hole at the left side of the mount seen above as the second bolt location. So as to do it I have cut these parts: and have them welded as my TIG welder is DC and wont weld aluminium: as for the third bolt, I decided to make a steel part that would bolt on the engine itself where the oil return flange was. It has two M8 bolts. I have designed that simple part which would go between the aluminium mount and engine block: this part will fit here: I decided to have the part laser cut, I have ordered it and will collect it tuesday. For the other side of the engine, again only one bolt is at the same location and can be used. I have grind the mount a little bit to fit it on the TDI engine: Also I had to cut the dipstick tube of the TDI, no problem as the LT dipstick tube is on the oilpan. I will cut an aluminium part and weld it on the mount to use the other near holes for bolting. Here is a sketch: (yellow lines) All photos can be seen here: Edited by mechano - 16 Jan 11 at 21:51 |
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Alevaro
Newbie Joined: 03 Oct 10 Location: Odessa, UA Status: Offline Points: 9 |
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cnycl Excellent work! |
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cnycl
Groupie Joined: 22 Dec 09 Location: Istanbul/Turkey Status: Offline Points: 118 |
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Thanks but compliments go to Mechano he's the one struggling with TDI engine in freezing cold weather. |
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mechano
Not Quite Newbie Joined: 15 Jan 10 Location: Ankara / Turkey Status: Offline Points: 37 |
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A little update:
I finished the turbo side engine mount. Here is the steel part I made which goes between the engine block and the aluminium mount: This is how it looks like when the oil filter is in place: Also I started working on the other side, I have cut an 8mm thick Aluminium sheet to weld to mount as I have sketched before: slowly... |
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GT500
Groupie Joined: 02 Jul 09 Location: leeds Status: Offline Points: 145 |
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Looking very nice!
Great help to me.. I think i'm going to get a spare engine from the LT I'm breaking.. need to have mine off the road as little as possible. Stripped the A6 and are slowly going through the rats nest of a wiring loom.. Very boring! |
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Rob... The only LT on 18" wheels.
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Canada LT28
Vanorak Joined: 03 Jan 10 Location: Toronto Status: Offline Points: 1632 |
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Hi Guys,
Eren, regarding the 1.9tdi, I will be cutting the prop shaft back to either put in a laycock overdrive (if i can find one at a reasonable cost) or a friend has a BMW 318 tranny that we are looking at putting in. Either way, Can I make the engine placement back far enough to still fit in and also miss the front end? |
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