TDS Conversion?

Post Thu Jan 15, 2009 12:02 am

I'm considering converting a 325i Touring to 525/325 TDS engine, purely for the sake of commuting and fuel economy. I can't remember seeing anyone on here with one so I was wondering if this was feasible or not...

Post Thu Jan 15, 2009 11:03 am

i think the reason being it hasnt been done is because the tds engine dosnt do many mpg its only a little better than a good e30 325i

Post Thu Jan 15, 2009 11:47 am

It's better than the m20 in eco for sure, if you drive it right. They really start to drop eco after 80odd keep off boost and don't hoon it on the nationals and it'll do quite well.

When I had my 325tds I was told diesel pump failure is common and sure enough it turned out that it was starting to go funny so that's something to be wary of.

Having said that - I thought about the same conversion mysef - I think it would be very very cool for a daily e30.

Post Thu Jan 15, 2009 1:27 pm

I would have thought LPG would be a better and easier solution.

Martin.

Post Thu Jan 15, 2009 3:10 pm

Turbo diesel would be more of a fun conversion though, playing around with inter-coolers and boost would be interesting

Post Thu Jan 15, 2009 3:21 pm

its been thought about and i think someone did it? i love the idea of a diesel e30 for the reason above /\ and for eco.

they are about 140bhp if im right? good lump of the torque too.

if it was just an eco runner i dont know how eco it would be to buy all the parts and then switch? getting your money back in fuel costs etc.

just grab a nice 318i as they are pretty good on fuel arnt they.

Post Thu Jan 15, 2009 3:27 pm

In the e36 it had plenty of pull would be nice in a 30.

Yeah - I measured 143 in mine. Something like 16psi boost.

Post Thu Jan 15, 2009 3:37 pm

Here is one for you to read through:

http://www.e30zone.net/modules.php?name ... c&t=117100

Post Thu Jan 15, 2009 4:36 pm

Im be buying a TDS donor car in the next few months for mine

Post Thu Jan 15, 2009 7:34 pm

I've thought aboout this a bit, E30 325tds touring anyone? Just because I like the engine, I know it's not financially sensible.

The Tds block is based on the M50 block (steel) so I reckon fitting it should be exactly the same as 24V M50.

The gearbox is unique to the tds.

Be aware the rear diff on E36 is 2.56:1 which will cause you problems with massively short gearing on a standard E30 diff. The tallest direct fit is 3.15:1 from a Z3 I believe, which is still way too short. In my opinion the gears are too short on the E36, with less weight in the E30 this would be exagerated any ideas anyone for taller gears?

My plan would be to use the standard high pressure fuel pump, unrestricted and free flowing. The high pressure won't cause any problems for the diesel pump but maybe the fuel filter, I'm not sure.

The boost tolerance in the tds is 0.9 to 1.1 bar from BMW.

Standard 143bhp, 195 lb/ft

Easy 40mpg in E36 so expect more in an E30

The engines can be chipped successfully to about 170bhp

Post Thu Jan 15, 2009 8:04 pm

I was planning on using an M20 gearbox.
Im looking forward to getting stuck in but got bodywork to sort out before I get to that stage.
With a chip box they are good for about 250lb/ft I believe?

Post Thu Jan 15, 2009 9:34 pm

I think its a great idea i nearly tried it when i was offered a e36 325tds for free but i was in the middle of my m50 conversion,
I reckon the exhaust would be easyer than a m50 because the head is not as wide ,
What about all that torque through the poor old diff mount though it might need beefing up

Post Thu Jan 15, 2009 10:10 pm

http://64.233.183.101/translate_c?hl=en ... lSfls7Gy8A

Post Thu Jan 15, 2009 10:12 pm

dicko wrote:What about all that torque through the poor old diff mount though it might need beefing up

They seem to handle M30's and some turbo M20s well enough.

Post Fri Jan 16, 2009 2:42 pm

Interesting link EKO. With a supersharger and no throttle body I guess it would feel like a bigger capacity NA diesel. I like the turbo spooling up and that shove in the kidneys, a newer faster spooling turbo would be a nice upgrade me thinks

Post Sat Jan 17, 2009 10:21 am

Great information. I have to say I'm liking the idea of a 325i touring TDS, and it should be a fair amount lighter on the wallet than a 325i would be. I currently drive a 318is and get 30mpg out of it out and about, so for commuting I was hoping for a bit more. I'm well aware of LPG but I completely forgot it in this instance

. I'm doing an M50 conversion in my E21 and thought about doing this for 325i touring (which I already have laying in wait) as a daily, but I'll be doing 110miles a day so I thought a TDS conversion maybe more sensible. Then again an M50 on gas is a tempting prospect!