Viewing: Is it possible to give diesels a little something off the line?

**Reubiedoo** · 22-04-2010, 06:22 PM

Without N2O?

i.e uprated clutch? do shortened gear ratios help? etc.

**pgarner** · 22-04-2010, 06:24 PM

shortened gear ratios are worse for diesels as the powerband is so small, longer gearing is used to get the best out of it.

big turbo, better mapping , losing alot of weight remember diesels are heavier than petrols

***HDi fun*** · 22-04-2010, 06:51 PM

You can get 'em off the line pretty smartly if you dial in about 1500rpm before letting the clutch in. The biggest problem is likely to be chronic wheelspin if the ESP is turned off.

Shorter gearing does not help as without load on the engine you will not get any turbo boost pressure at all.

**Reubiedoo** · 22-04-2010, 07:29 PM

Thanks guys.

**jarrus** · 28-04-2010, 08:01 PM

Diesel's are geared short in 1st and 2nd so they aren't great off the line and due to the fact they have more torque to contain

***HDi fun*** · 28-04-2010, 09:20 PM

They're not short geared so much as short of revs.

**jarrus** · 28-04-2010, 10:53 PM

Fair point, well made, however they could lengthen the gears a bit to compensate for the lack of rev's but i suppose that most modern diesel can't really maintain the big torque across the rev band because of the tiny turbo's they have, twin turbo's help but haven't really solved the problem,
I know this is a point I shouldn't mention because it cause's a lot of arguments, but I still believe that diesels are still somewhat "rained in" so that they aren't as quick as there petrol counterparts, I believe that this does have something to do with it,
Diesels are always made for low down torque and bigger numbers, however (and it can be done) if they sacrificed just a bit of low down torque (and trust me you probably wouldn't notice) so it can be used else where then you could build yourself a genuinely drivable indecently fast car that could produce big torque across it's whole rev band and still do 40 mpg, I'd love the opportunity to prove that I'm not talking out of my arse, I have a distinct lack of funding for the job

***HDi fun*** · 29-04-2010, 08:17 PM

Mine managed a good spread from below 1500rpm to nearly 5000rpm. Basically you could treble your speed in ONE gear. It went fairly well.

**jarrus** · 29-04-2010, 10:16 PM

Nice, but I did some digging and found that the 2.2 hdi had quite a small turbo really, gt15 is rather small for the engine size I would say,
I also did some more research on the 306 2.2 hdi, it uses a gt22 turbo obviously a VNT type but this is what I'm on about something like that would help the power spread big time

***HDi fun*** · 29-04-2010, 10:45 PM

Quote:

Originally Posted by jarrus464

Nice, but I did some digging and found that the 2.2 hdi had quite a small turbo really, gt15 is rather small for the engine size I would say,
I also did some more research on the 306 2.2 hdi, it uses a gt22 turbo obviously a VNT type but this is what I'm on about something like that would help the power spread big time

It (my 406 with the DW12TED4) had a Garrett AiResearch T3. Which is, as, you say, very modest. But it still managed to twist 320+ lbft and over 190bhp with a remap.

And it did go quite pleasantly.

**jarrus** · 29-04-2010, 11:08 PM

Quote:

Originally Posted by HDi fun

It (my 406 with the DW12TED4) had a Garrett AiResearch T3. Which is, as, you say, very modest. But it still managed to twist 320+ lbft and over 190bhp with a remap.

And it did go quite pleasantly.

Indeed I bet it moved, lol they phased out t3's and t2's ages ago so it would just be equivalent then I guess