[rainbowcar]

If you wanted to get some serious performance out of one of these MK3 diesel lovelies, what would you do...

I'm considering making a bit of a fast diesel project of mine but am newish to diesel... any ideas?

 

[TDCi 160]

Well its an expensive hobby mate but for bigger than normal bhp from a diesel theres a couple of things i can think of. Bigger turbo, big intercooler, induction kit, NOS, remap etc. Dont know if its possible with a modern diesel but you could look into bigger injectors, camshafts, etc. Or you could try transplanting a 2.2 TDCi (155bhp) into yours and then go to work on that with some of the above mods?? If you want to keep cost down to a sensible level then a remap, induction kit, exhaust, and possible intercooler should see about 150-160 ish bhp from a 115 TDDi?

 

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[rainbowcar]

Was thinking along those lines...

upping the boost pressure is an obvious way but you would of course need to think about increasing the fuelling too. since the correct fuel air mixture is 14:1 if i can increase to oxygen levels the fuelling would need to match, obviously there are limits... ie how much pressure the intake manifold can take, how much fuel the injectors/injector pumpo/fuel pump can provide. do you know how much boost pressure the turbo provides as standard? atmospheric pressure at sea level is 14.7 = 1 bar.

the formula for gains is stock boost preesure(SBP) -atmospheric pressure(AP) = Stock turbo pressure(STP)

(STP/Modified Turbo pressure)x100 = percentage bhp gains

this works providing

a: you can keep the fuelling correct

b: you can keep the intake temperature the same. (unlikely)

so if you expect to lose 10% to intake temp to get a 50% gain you would need to (assuming 20psi standard) find a turbo that gives 18 psi(!) above AP which would make boost = 14.7+18= 32.7psi

that mega pressure - you would lose 10%(for the sake of argument) due to the fact that intake temp would be higher(more than just a bigger ic would be needed to keep it the same temp).

that would only give just over 170 bhp, this is once you have put on the bigger fuel pump, remapped the ECU!!!

lightening things like cams/flywheel etc could be a bad move,

certainly it would be more revvy but you would lose torque! and what's a diesel without torque!!!lol

the only other option I can think of is supercharging, although this is more wasteful than turbocharging ie the supercharger might provide 45% more power it can also consume up to 20%!!! running a centrifugal supercharger alongside a turbo would limit lag, and increase to boost massively in the higher revs but the bottom end would remain largely unchanged.

I know there are some obstacles so i'm just wondering whether i moght be as well saying bugger it and buy a petrol!!!

 

[rainbowcar]

starting to think the 2.2 transplant idea is a worth thinking about...

as everything is about percentage gains i.e. not that a mod will give x amount of power but x percent of your stock/current power; it makes sense to start with as much as possible!!!

will look into it

 

[sparker]

(more than just a bigger ic would be needed to keep it the same temp)

You would need to fond a more efficient IC. Which im sure wouldnt be too hard at all. I dont know much about diesels but can you use water injection with them?

the only other option I can think of is supercharging, although this is more wasteful than turbocharging ie the supercharger might provide 45% more power it can also consume up to 20%!!! running a centrifugal supercharger alongside a turbo would limit lag, and increase to boost massively in the higher revs but the bottom end would remain largely unchanged.

A centrifugal supercharger woulnt be any more use than a turbo. It works on the same principle as the turbo, except it is belt driven. You would be better off looking at a twin screw supercharger if you were going to go down taht route. They are teh most efficient superchargers and produce power from the word go

 

[rainbowcar]

yeah i know what your saying with the ic, but with space restrictions the intake temp is bound to rise with large boost increases.

yes you can use water/ethanol injection, ethanol being better as it will not preignite with the pressure but will increase power loads!!! risky though as an incorrect set up gives dire consequences.

I am with you with the centrifugal SC but the idea was to run it at the same time as the turbo to give bigger top end gains to make the car more suitable as an everyday road car and an occasional track day monster... using a twin screw would certainly eliminate lag and improve the bottom end until the turbo takes over... so to get proper gains a bigger turbo would be needed too, also twin screws are much bigger and would need more fettling of engine bay to fit!!!

 

[sparker]

The thing about teh twin screw is that you have teh advantage of always being on boost. Turbos and centrifugal superchargers only give boost at higher revs (higher exhaust flow really) roots superchargers are decent at lower revs, but top out too easily. The twin screw will give power from the word go, and will continue to give decent boost until you come off the gas pedal.

With these facts id probably just dump the turbo and go twin screw, getting one thats designed for a much larger engine so atht you can get the high boost.

The problem with runing super and turbo chargers together is taht the supercharger will always be draining power. Altho also running the turbo makes it more efficient i suppose as teh extra boost comes from wasted energy (hot exhaust gases) but not enough to cancel out the supercharger drain.

Iv hummed and haued abouth wich root to go myself. In teh end i decided turbo charger (which will come later in the year) but as a compromise decided to add ITBs for better off boost response. However i dont know if there is a diesel equivalent as i know diesels dont use throttles (im pretty certain)

 

[rainbowcar]

The twin screw will give power from the word go, and will continue to give decent boost until you come off the gas pedal.

sounds exacly what i was looking for, the description I read made the twin screw sound pretty much like a roots SC so had sort of discounted it. disconnecting he turbo... sounds tricky, messing with the exhaust system.! :sad:

 

[kithmo]

IIRC there was an LPG injection kit that gave up to 40% hike in power on a Diesel.

 

[sparker]

the twin screw is a bit like a roots charger, except it compresses the air as it goes in, like a turbo does. The roots charger forces the air in and the pressure builds inside the manifold. Thats why roots chrgers are inferior. It basically has all the good points from both centrifugal and roots

 

[Sisson]

IMO, if you want a high powered diesel.

look at the vag pd130 or pd140.

I know of a few PD130's with around 220bhp and one that had 245bhp.

also i know of a pd140 with nos and lpg injection that is near enough 300 horses!!!

have a look at www.allardmotorcompany.co.uk for more info

 

[rainbowcar]

IIRC there was an LPG injection kit that gave up to 40% hike in power on a Diesel.

thats cool, definitely on the list! :L - LPG is similar to ethanol, has a higher octane (much higher) than diesel so will not preignite, it is an oxidiser so effectively gives more oxygen into the chemical reaction on the compression stroke = more bang!

 

[ScoobyChris]

look at the vag pd130 or pd140.

I know of a few PD130's with around 220bhp and one that had 245bhp.

And to get there, requires a FMIC, custom remap, free-flow exhaust, bigger (hybrid?) turbo, better clutch, LSD, LPG/propane injection, etc, etc which could all be done to a TDCI without problem

Chris

 

[derv]

uprated injectors too?

 

[rainbowcar]

as I work through this, ie FMIC - needs a remap, then bigger turbo etc... needs remap.

basically after every major change I shold really have the fuel map altered. any way I can do this without spending like £300+ a pop? something for
PC perhaps?

 

[ScoobyChris]

The easiest way is to do all the mods first and then get the car remapped once You might also find that tuners charge a lot less for minor tweaks to the map than the initial map

Chris

 

[rainbowcar]

I might speak to a tuner about it, as i don't know how long it is going to take i don't want to be running mods that are causing me to run lean/limp mode etc...