Petrol vs diesel

[Biscuit]

In a straight line the Diesel would be faster but I'm any twisties it would end up in a hedge if it tried to keep up. Chipping those engines is a good way to munch through clutches as well.

[DanceswithUnix]

In a straight line the Diesel would be faster but I'm any twisties it would end up in a hedge if it tried to keep up. Chipping those engines is a good way to munch through clutches as well.

Not convinced it would keep up in a straight line tbh.

People rave about diesel torque figures, but once it has been through the typically 50% higher gearing of a diesel gearbox what you get at the wheels isn't much better. Then there is the fact that the torque figure is simply the available torque, the figure you can't exceed without stalling the engine. Unless you are seriously hill climbing or towing you won't be torque limited anyway, it will be like running a £50 graphics card on a 1500W PSU, you just don't need the headroom. So in a straight level line it comes down to bhp doing work on the mass of the car to increase the velocity, and even after a remap the diesel won't be getting the power of the type-r, and it has the extra weight of the heavier engine to work on as well.

And in case anyone says it isn't that simple, I am aware that bhp is the integral of torque minus losses so in that respect torque does matter, but the reality is torque makes a car nicer to drive (specially in low down V6/V8 form) but bhp per ton is what matters 0-60. If you don't believe me, try a 350lb-ft diesel against a 96lb-ft Ducati.

But yeah, torque at the flywheel will directly apply to the clutch, one of the reasons my diesel isn't chipped (along with insurance implications, doesn't seem worth the costs).

[eagle123]

Not convinced it would keep up in a straight line tbh.

People rave about diesel torque figures, but once it has been through the typically 50% higher gearing of a diesel gearbox what you get at the wheels isn't much better. Then there is the fact that the torque figure is simply the available torque, the figure you can't exceed without stalling the engine. Unless you are seriously hill climbing or towing you won't be torque limited anyway, it will be like running a £50 graphics card on a 1500W PSU, you just don't need the headroom. So in a straight level line it comes down to bhp doing work on the mass of the car to increase the velocity, and even after a remap the diesel won't be getting the power of the type-r, and it has the extra weight of the heavier engine to work on as well.

And in case anyone says it isn't that simple, I am aware that bhp is the integral of torque minus losses so in that respect torque does matter, but the reality is torque makes a car nicer to drive (specially in low down V6/V8 form) but bhp per ton is what matters 0-60. If you don't believe me, try a 350lb-ft diesel against a 96lb-ft Ducati.

But yeah, torque at the flywheel will directly apply to the clutch, one of the reasons my diesel isn't chipped (along with insurance implications, doesn't seem worth the costs).

The honda ictdi diesel engine revs like a petrol it has enough oomp to 4500 revs, yet i meant if you upgrade the clutch/ suspension and brakes it will be match against the type r, dont forget that the fuel economy of the diesel is way better than the type r.

The diesel superior torque means the in gear time is faster, the type r is faster after you push the engine to 5000 revs when you get the vtec on, so in normal driving the diesel more enjoyable to drive, being more flexible, but in a race track the type r edges it,

[Guy]

But then with all the £££ spent on modifications (remap, clutch, brakes) that's many thousands of miles in unleaded.

I've never understood the ingear arguments either, as yes it's nice having the flexibility to plant your foot and use the lower down torque surge to get you going. But comparing the 2 if you wanted the Type R to get going you'd just drop a cog or 2 as you just wouldn't floor it in 6th and expect it to move.

[scaryjim]

... you'd just drop a cog or 2 as you just wouldn't floor it in 6th and expect it to move.

From an ex Rover 414 driver, this The 1.4 K-series engine was beautiful in many ways, and generated over 100bhp, but had no low end torque. I loved driving it on the motorways, but moving to the Yorkshire Dales within 6 months of buying it was not my best decision

It's daft to buy & mod a car just so you don't have to change down gears if you want to accelerate - if you're that averse to gear shifts just buy an auto and have done ...

[DanceswithUnix]

The honda ictdi diesel engine revs like a petrol it has enough oomp to 4500 revs, yet i meant if you upgrade the clutch/ suspension and brakes it will be match against the type r, dont forget that the fuel economy of the diesel is way better than the type r.

Seems odd to say having oomph up to 4500 rpm is like a petrol car when and decent petrol car will red line around 7K at least. My last petrol was a 2.5 v6 and I had that at 7500rpm almost daily

And I have to agree with Guy, if you find yourself modding a car then that is either a hobby in itself (and I suggest you go buy an MR2 turbo or a kit car) or you started with the wrong vehicle. The costs just don't add up.

Sounds like you have a lovely car, but appreciate it for what it is. If you want it to rev like a petrol, get petrol. If you want torque and something that is really easy to drive, then honestly you need more cylinders. If you really like the way a diesel feels, and plenty of people do, then if you want more performance there are plenty of Audi & BMW options to choose from.

But overall it sounds like you went from something like a 90bhp petrol engine to a 140bhp diesel, so yes it is easier to drive. I went from a 190bhp petrol to a 150bhp diesel so I got the opposite. My main complaint though is that the seats aren't as comfy, I can live with the reduced torque & power given it is a cheaper car to run generally.

[peterb]

If you want torque and something that is really easy to drive, then honestly you need more cylinders. If you really like the way a diesel feels, and plenty of people do, then if you want more performance there are plenty of Audi & BMW options to choose from.

True! A six cylinder diesel drives beautifully - very smooth and loads of torque - but to get low end acceleration, they tend have a low first gear, so it is very easy to hit the relatively low redline at about 500RPM. An instance where mating it with an automatic would make sense.

[DanceswithUnix]

True! A six cylinder diesel drives beautifully - very smooth and loads of torque - but to get low end acceleration, they tend have a low first gear, so it is very easy to hit the relatively low redline at about 500RPM. An instance where mating it with an automatic would make sense.

Not tried a diesel 6 pot, but I suspect you could make a coal burning 6 and it would still be nice to drive

With a petrol V6 I often don't bother with first if I want to drive smoothly (eg there are passengers in the car, or a takeaway curry in the passenger footwell).

[Guy]

From an ex Rover 414 driver, this The 1.4 K-series engine was beautiful in many ways, and generated over 100bhp, but had no low end torque. I loved driving it on the motorways, but moving to the Yorkshire Dales within 6 months of buying it was not my best decision

It's daft to buy & mod a car just so you don't have to change down gears if you want to accelerate - if you're that averse to gear shifts just buy an auto and have done ...

Interestingly if you look at the dyno figures for mine, it doesn't actually hit the peak torque figure until just before the 3,000rpm figure.
So if you really want to get moving more often than not going down the box one or two can help.
But it's a trade off I like, as it's very un dieselesque to drive!

The majority of people opting for a 6 pot derv have it mated to an autobox which I can understand as I've had both, but until v v v recently (8 speed ZF) it's not been quite as engaging to drive and you took a hit on the fuel economy, but it made for a less demanding ride and was a godsend in traffic and trawling through London!

[herulach]

But then with all the £££ spent on modifications (remap, clutch, brakes) that's many thousands of miles in unleaded.

I've never understood the ingear arguments either, as yes it's nice having the flexibility to plant your foot and use the lower down torque surge to get you going. But comparing the 2 if you wanted the Type R to get going you'd just drop a cog or 2 as you just wouldn't floor it in 6th and expect it to move.

I've never driven a newer type R, but older hot honda engines tended to be really quite pap till the vtec kicked in at whatever rpm, A friend at school had a type-r breadvan civic that needed its nads absolutely ragging off to perform decently, or at least it did till he put it in a hedge.

To my mind diesels have more of the characteristics of say a big V8 than a 'sporty' engine, (6 cylinder BM ones excepted as they're great) They're much more relaxing to drive quickly, and in many ways a lot more fun (as the kick up the arse is satisfying if nothing else) but for genuinely fast driving a high performance petrol is pretty much always going to be better (things like the R8 TDI etc notwithstanding of course!)

[peterb]

Not tried a diesel 6 pot, but I suspect you could make a coal burning 6 and it would still be nice to drive

Now there's a thought - turn the coal into fine dust, and aerate it so it acts like a fluid.....

Might be a bit abrasive though

Probably better to keep it for use with external combustion engines!

[Biscuit]

The honda ictdi diesel engine revs like a petrol it has enough oomp to 4500 revs, yet i meant if you upgrade the clutch/ suspension and brakes it will be match against the type r, dont forget that the fuel economy of the diesel is way better than the type r.

The diesel superior torque means the in gear time is faster, the type r is faster after you push the engine to 5000 revs when you get the vtec on, so in normal driving the diesel more enjoyable to drive, being more flexible, but in a race track the type r edges it,

It doesn't edge it, it demolishes it. There is very little competition on the track.

If you spent the same money as you did to mod the diesel on the type R. It would again be on top by quite a distance. With moderate cash you can get 220-230BHP and lower the iVtec kick to bring the torque in earlier.
Most people focus on suspension, breaks, LSD as that is what really makes a Type R fun.

[eagle123]

Seems odd to say having oomph up to 4500 rpm is like a petrol car when and decent petrol car will red line around 7K at least. My last petrol was a 2.5 v6 and I had that at 7500rpm almost daily

And I have to agree with Guy, if you find yourself modding a car then that is either a hobby in itself (and I suggest you go buy an MR2 turbo or a kit car) or you started with the wrong vehicle. The costs just don't add up.

Sounds like you have a lovely car, but appreciate it for what it is. If you want it to rev like a petrol, get petrol. If you want torque and something that is really easy to drive, then honestly you need more cylinders. If you really like the way a diesel feels, and plenty of people do, then if you want more performance there are plenty of Audi & BMW options to choose from.

But overall it sounds like you went from something like a 90bhp petrol engine to a 140bhp diesel, so yes it is easier to drive. I went from a 190bhp petrol to a 150bhp diesel so I got the opposite. My main complaint though is that the seats aren't as comfy, I can live with the reduced torque & power given it is a cheaper car to run generally.

Actually i had a mark 1 jazz it was 82 bhp but idsi so its engine has similar characteristic as a diesel, the mk2 jazz has a vtec engine, the idsi engine peak torque figure delivers lower revs than the vtec from the jazz mark 2.

Driving the diesel civic to me its very similar to the idsi engine, but with more poke, having driven the jazz for 7 years and now moving on to the civic, i tend to drive gently, and change up early, but i have to adjust my driving style as the civic has a more powerful engine, do get caught out when i press the accelerator pedal then whoosh, unlike the jazz where it takes a while to pick up speed.

the jazz has its advantages, its roomy, reliable, but its fuel economy is mixed, short journeys i tend to get low 30 mpg, on the motorway its 40 mpg, despite having had full honda dealer service history.

Now the civic roughly 20 percent better fuel economy, but a big jump in bhp and torque, i still need to get used to driving the diesel like waiting for the glow plug to go out then start up, it sounds rattly in the first minute then calms down when it warms up, i fancied the type r but wanted 5 doors and good fuel economy so diesel civic was a better car for me

[Butcher]

I've never understood the ingear arguments either, as yes it's nice having the flexibility to plant your foot and use the lower down torque surge to get you going. But comparing the 2 if you wanted the Type R to get going you'd just drop a cog or 2 as you just wouldn't floor it in 6th and expect it to move.

My petrol has 280 lb-ft of torque which is comparable to many diesels; it's still a lot faster when you rev the nuts off it in third rather than trying to use the torque in 6th. That will be the case for all cars though unless the torque drops off dramatically at high revs, due to power being revs * torque.

[DanceswithUnix]

Now there's a thought - turn the coal into fine dust, and aerate it so it acts like a fluid.....

Might be a bit abrasive though

Probably better to keep it for use with external combustion engines!

Many years ago some chap in Australia designed an engine that used multi stage compression pistons, kind of like a jet engine but done with pistons instead of turbines. ISTR he did try burning coal dust in it, as with enough compression it would burn absolutely anything which I think was a main driver in the design if you live in the outback and want flexibility on what fuel you can burn. Seemed a cute idea, guess it never took off though.

My petrol has 280 lb-ft of torque which is comparable to many diesels; it's still a lot faster when you rev the nuts off it in third rather than trying to use the torque in 6th. That will be the case for all cars though unless the torque drops off dramatically at high revs, due to power being revs * torque.

Petrol engine cars seem to be set to cruise around 3K rpm, diesels around 2K rpm, so the gearboxes have different ratios. So your torque at the flywheel is, assuming that 2/3 ratio difference in ratio setup, equivalent to a diesel making 420 lb-ft once you get to the wheels. Massive approximations used, ymmv, but it fits in with how cars I have driven have felt.

[peterb]

Many years ago some chap in Australia designed an engine that used multi stage compression pistons, kind of like a jet engine but done with pistons instead of turbines. ISTR he did try burning coal dust in it, as with enough compression it would burn absolutely anything which I think was a main driver in the design if you live in the outback and want flexibility on what fuel you can burn. Seemed a cute idea, guess it never took off though.

You got me searching.. didn't find the chap in Australia - did find this though http://news.google.com/newspapers?ni...g=5236,3682431


Not very practical for a car (and getting off the original topic) but quite interesting though!