AHU with stock gearbox

for questions and answers about alternative power transplants on the T25, GTi, Porsche,Subaru etc, this is the place. You must register to post but anyone can read.

Moderators: Moderators, User administrators

Post Reply
User avatar
airhead
Posts: 877
Joined: 18 Oct 2005, 14:47
80-90 Mem No: 2980
Location: Dublin, Ireland.

AHU with stock gearbox

Post by airhead »

Hi folks. My AAZ has had its last adventure in the camper and has essentially past the point where I feel I can trust it to not let us down in spectacular fashion. So I picked up an AHU with low enough mileage and a modified harness. I have it in my means to put this engine in and make it work but my budget won't allow for the gearbox mod at this point, so I have a few questions...

Is anyone on here running a TDI with stock box? What are your experiences? I know the engine isn't in it's correct power band with this box but aside from poor fuel economy what does this entail?

The engine has a solid flywheel and a new clutch with it. If I go easy on it and don't do any hard launches will I get away with this?

I have the wide intercooler from a seat Alhambra. Where have people fitted these?
Ross

1987 1.9td Leisuredrive camper.

User avatar
Aidan
Trader
Posts: 5040
Joined: 11 Oct 2005, 19:21
80-90 Mem No: 742
Location: Llanfyllin, mid Wales : )
Contact:

Re: AHU with stock gearbox

Post by Aidan »

AHU being twin valve spring engine is able to run at higher revs more happily and that is the answer, use the revs rather than trying to always run at the lowest revs you can and lugging it around on the torque, that's what the gearbox doesn't like, don't pull away in 2nd gear from cold standing start and be happy at 55-60mph top speed or what ever your ears will put up with rev wise, it probably won't make any difference to the fuel economy, and you can gear up with bigger than standard tyres to mitigate the effects

User avatar
Dobble
Posts: 210
Joined: 25 Apr 2017, 20:23
80-90 Mem No: 15944
Location: South Glos

Re: AHU with stock gearbox

Post by Dobble »

I'm running an AHU engine in my Syncro with a mechanical pump. It's running standard gearing in the box but the gearing in the diffs has been changed as far as I know (5.43 originally now 4.86). With the set up I'm running I cruise at 55-60, it will go faster but it sounds a bit harsh.

I've not really checked the MPG, when its empty I fill it up.

I'm not sure which intercooler I have but its mounted behind the near side light cluster. I can get some pictures if you like?
1987 T25 AAZ RHD Syncro
1989 T25 MTDI RHD Syncro

User avatar
airhead
Posts: 877
Joined: 18 Oct 2005, 14:47
80-90 Mem No: 2980
Location: Dublin, Ireland.

Re: AHU with stock gearbox

Post by airhead »

Thanks lads. My intercooler won't fit behind the light cluster so I'll have to be more creative. I'm thinking it might fit over the gearbox widthways in the engine bay and I could bring some ducts up to it from under the van to direct some cold air to it.

I've kind of made a decision anyway to do the passat box conversion now anyway, cause I can get a box for €120, and it will make the van a lot nicer to drive. Obviously I've to get all the conversion parts on top of that so I'd say it could work out closer to the €1200 mark by the time it's in but that's still small money all things considered, and my current box is hopping out of 2nd the odd time anyway.

Cheers for the input.
Ross

1987 1.9td Leisuredrive camper.

Post Reply