coyoteboy
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 posted on 8/9/10 at 10:17 AM |
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Diesel
I know. Words that shouldn't be uttered in sports car world, but with the advent of things like the Iceni and the R8 V12 TDI, is it really
something to be avoided?
I mean you can easily get 200hp from a 2 litre. It's a bit portly for a 2 litre but not too bad - I'm currently trying to find exact
weights but I'm guessing they're not far off the iron block petrol 2 litre I have. Certainly I can easily bench-press the front of my
2litre HDi upward by 5 or 6 inches, but I can move my petrol 2 litre upwards by no more than an inch or so, suggesting much higher mass in the
petrol.
Curious as to your thoughts. I mean the power band may be much smaller (1500-3000 on my HDi) but if you realise it has the same top end as a 7Krpm
petrol and scale its redline of 5k up to the 7k you're talking 2100 to 4500rpm equivelent (same as many V8's), and if you get the ECU
re-tuned (costs as little as £100 even for a good mapping) you can stretch the power band up to 4Krpm which equates to about 5600rpm with the equiv
petrol and 5 speed box. And there are more spritely engines than the PSA 2.0HDi.
Thought I'd throw it out there and see what got fired back...
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UncleFista
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| posted on 8/9/10 at 10:29 AM |
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Strangely enough I watched a couple of youtube clips last night of a Pug 205GTi fitted with a 2.2 HDi engine.
It didn't look any slower than the petrol version 
Tony Bond / UncleFista
Love is like a snowmobile, speeding across the frozen tundra.
Which suddenly flips, pinning you underneath.
At night the ice-weasels come...
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coyoteboy
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| posted on 8/9/10 at 10:34 AM |
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VAG V6 3.2 petrol weighs 169kg:
188 kW (255 bhp) at 6,500 rpm; its peak torque of 243 lbs-ft is available at just 3,250 rpm.
VAG 3.0 V6 TDI weighs 219kg:233 bhp and 330lb ft. Maximum torque is available at a mere 1,400 rpm
[Edited on 8/9/10 by coyoteboy]
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PAUL FISHER
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| posted on 8/9/10 at 10:38 AM |
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Its been discussed in the past a few times.
http://www.locostbuilders.co.uk/viewthread.php?tid=16267&page=1
http://www.locostbuilders.co.uk/viewthread.php?tid=118097
[Edited on 19/05/04 by PAUL FISHER]
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iank
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| posted on 8/9/10 at 10:45 AM |
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Currently they can make a lot of sense where there are class mulipliers.
I've seen class breaks where diesel gets a 0.5x and turbo 1.4x multipliers. This puts a 1.9 TDi in with 1400cc petrols.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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coyoteboy
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| posted on 8/9/10 at 11:13 AM |
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Paul - first thread is just the usual senseless "no, don't do it" answers, second thread is slightly more involved but essentially
contains two polars - no, don't do it and "ive got one, it's good fun". The reason I asked is because I wasn't satisfied
with the answers in previous threads.
However most seem interested in the old engines where power/weight was aweful. I recognise the ECU problem but it really isn't a problem unless
you like mapping things yourself at home.
While I'm willing to accept there are pros and cons, I don't like the abrupt "no" answers as I think they're just not
thought through. People claim small powerbands, but they're not when you realise the redline is lower and that just because it doesnt scream at
you doesnt mean it's not as quick/fun to drive. There's loads of them around now, they're competitive on power and torque but a bit
heavy, but some of the smaller 1.6 and 1.4 TDs can output as much as a zetec 2 litre of the same mass.
[Edited on 8/9/10 by coyoteboy]
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nick205
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| posted on 8/9/10 at 11:21 AM |
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What application are we talking about?
Race
Road
Kit install
As you say the very latest crop of diesel motors are really very effective. When you consider that earnest road car diesel development only really
started a decade or so ago they probably have may more incremental improvements to make over the next few years.
In a race situation, would the reduced fuel load or extended range over petrol serve to offset the higher mass of a diesel motor...?
[Edited on 8/9/10 by nick205]
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dinosaurjuice
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| posted on 8/9/10 at 11:50 AM |
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i have a 2.0l TDCI (latest pug Hdi) in my MEV Rocket. completely standard 136hp, 250lbft torque. power band is excellent, 1500-4000. Cruises at 70
doing 2000rpm, only clatters like a diesel when idling, very smooth when moving.
engine and 6speed gearbox are about 240kg.
never averaged less than 50mpg... cant be a bad thing these days?
video of having some fun at curborough: YOUTUBE LINKY
as said, if ever i want more power, i just hand over some cash for a remap. should see 170hp thereabouts without having to change clutch etc.
Will 
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MikeR
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| posted on 8/9/10 at 12:53 PM |
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blooming heck, a crossflow could make 136bhp with a 100kg less mass, i'd suspect a zetec without mods would make that with a good 90kg less
weight (guessed weights).
Whilst I like the idea of diesel and find this a very interesting thread, there is a lot of extra weight to carry.
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coyoteboy
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| posted on 8/9/10 at 12:55 PM |
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100kg is a lot of extra weight, I agree. Mental amounts. Though I think you under-estimate the weight of a petrol like that - IIRC K series is 110kg
built up, plus box. But bear in mind that that's baseline power with no modifications designed for taking you to the supermarket, and upgrading
that is as simple as "file>upload"... drive off.
My thoughts were based around having the old 90hp HDi, who's turbos retail for around £25 on ebay. And larger turbos for ~£50. And you can buy
the mapping hardware and software for about £50 for the stock ECU.
Will, that'll win no petrol owners over despite being rather cool and a proof of point you need to see the trident iceni in action 
http://www.cararticles.co.uk/uk-the-trident-iceni-%E2%80%93-a-70mpg-supercar.html
[Edited on 8/9/10 by coyoteboy]
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pekwah1
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| posted on 8/9/10 at 01:47 PM |
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well i drive diesel cars every day for work and cover a lot of miles in them. For a daily hack it's no contest, a petrol just doesn't
have the torque to be able to overtake on motorways with changing gears, and definitely won't give me the consumption.
On the negative, they just lack the responsiveness and refinement of a petrol.
It depends what you want out of it really. A petrol engine in a car like ours will be used for the throttle response and the fact that you get more
control out of the engine with the higher revs. I know you have said that effectively you have the same power band from a diesel, it's just
scaled down revs, but there is a big difference in how they drive, a petrol loves to be revved, whereas a diesel likes torque.
Obviously there are tuning techniques for a diesel to change the way it delivers the power, but you'll never eliminate the turbo lag, and
it'll always tail off towards the end of the power band.
So for me:
daily drive = diesel
daily toy = petrol
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dinosaurjuice
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| posted on 8/9/10 at 02:28 PM |
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a X'flow with gearbox, prop shaft and diff for 140kg? not sure about that.
VW tdi would be a better choice in hindsight. much simpler wiring than a HDi, particularly my CANbus controlled lump. and way over 200hp possible a
from a 1.9! a stronger engine than the HDi in my opinion, just not as refined.
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mcerd1
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| posted on 8/9/10 at 02:50 PM |
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for me petrol is just more fun
I'm watching to see how the 5 stroke petrols develop linky
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Vindi_andy
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| posted on 8/9/10 at 02:57 PM |
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you can always add a NOS kit to a diesel to get faster response.
They have kits that are designed for quick response ie for overtaking.
Saw 5thgear stick one on a golf
And Ive been toying with the idea of a sonic7 with roof doors and a TD engine out of a modernish focus, to get the 6 speed box, as a daily commuter
[Edited on 8/9/10 by Vindi_andy]
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iank
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| posted on 8/9/10 at 03:07 PM |
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quote:
Originally posted by mcerd1
I'm watching to see how the 5 stroke petrols develop linky
Interesting stuff, 130bhp from a 700cc turbo with diesel type consumption isn't bad.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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MikeR
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| posted on 8/9/10 at 03:16 PM |
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quote:
Originally posted by dinosaurjuice
a X'flow with gearbox, prop shaft and diff for 140kg? not sure about that.
Fair point - i was just thinking, engine and box. You may be edging towards 180kg when you include that lot (again pure guess here).
As for the focus 6spd, i drive one, i prefer the change and action of the 5 speed. You may want to consider that before you get one.
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coyoteboy
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| posted on 8/9/10 at 03:39 PM |
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I think the responsiveness of the D is due to the high fly mass pretty much entirely. It's a fair point I suppose, but because it's geared
down and running at lower revs, I wonder if the same responsiveness (at the wheels, through the box rather than at teh crank) is achieved? i.e.
250rpm/s on petrol = ~170rpm/s from the D due to gearing and additional torque. While the engine may not sound "urgent".
Throttle response of my HDi is pretty shocking though I agree, I mean its fly by wire throttle and if I stab the throttle I can hit the floor and back
up before the revs have raised 100rpm.
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mcerd1
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| posted on 8/9/10 at 04:01 PM |
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quote:
Originally posted by iank
quote:
Originally posted by mcerd1
I'm watching to see how the 5 stroke petrols develop linky
Interesting stuff, 130bhp from a 700cc turbo with diesel type consumption isn't bad.
the best thing about it is its so simple and there are no fancy production methods or exotic materials
the way I think about it (which may not be technicaly correct) is ist a bit like a double expansion steam engine....
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mcerd1
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| posted on 8/9/10 at 04:02 PM |
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quote:
Originally posted by MikeR
As for the focus 6spd, i drive one, i prefer the change and action of the 5 speed.
which 5 speed box is it you like - the IB5 or the MTX75 ?
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zilspeed
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| posted on 8/9/10 at 04:55 PM |
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I have na HDi engine in my hack car and it's a wonderful thing. So much torque from such low revs and very smooth too. It's a great
engine.
I do think though, that the use you put it to should influence the decision.
If you get a chance to pin the throttle and hold it there, there's a real chance that it could work, so powering up big straights might be
ok.
For tighter twistier stuff where a lost fraction of a second could cost you a win, it just wouldn't be the thing to use. In hills and sprints
for example, you can't be doing with turbo lag and there tend to be lots of slow speed corners where an off boost diesel would be useless.
I haven't experienced a diesel powered lightweight and repsonsive car, but for the reasons mentioned above don't fancy it much.
Bigger straights, faster corners, it makes more sense to me - and also, it appears Audi and Peugeot for their endurance racers. Although though
I'm sure class rules will have led them to that decision no doubt.
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Wadders
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| posted on 8/9/10 at 05:29 PM |
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Slightly off topic, but which modern diesel will readily fit to a RWD box ?
Al
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jeffw
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| posted on 8/9/10 at 06:25 PM |
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quote:
VAG V6 3.2 petrol weighs 169kg:
188 kW (255 bhp) at 6,500 rpm; its peak torque of 243 lbs-ft is available at just 3,250 rpm.
VAG 3.0 V6 TDI weighs 219kg:233 bhp and 330lb ft. Maximum torque is available at a mere 1,400 rpm
My 3.0TDi A6 is remapped to 295BHP and 430lb ft.....pretty quick for a 1900Kg estate car.
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mcerd1
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| posted on 8/9/10 at 06:46 PM |
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quote:
Originally posted by jeffw
My 3.0TDi A6 is remapped to 295BHP and 430lb ft.....pretty quick for a 1900Kg estate car.
but then 1900kg is a very heavy car
of course I'm used to 750kg tin-tops (I think my current focus is heavy at 1150kg)
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jeffw
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| posted on 8/9/10 at 06:54 PM |
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750Kg Tintop is very unusual these days. The A6 Avant is a big car (something like 16'.
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mcerd1
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| posted on 8/9/10 at 06:58 PM |
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^^ I never said they were new tin-tops
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