Why do diesels accelerate so slowly even with high torque?

[Bicolor]

What I mention applies only if you are at rest idling at traffic light. You try just flooring the accelerator while you are at rest at see the effect. Btw, when I say gradual stepping, I don't mean go slowly.

 

It actually bogs the car down rather than make it accelerate faster. Btw, it no longer affects new cars because the throttle is electronically controlled. Only cable ones.

 

I see, thanks for clarifying. I was referring not to accelerating from standstill, but rather to speeds required to filter into an expressway or highway overtaking speeds - my diesel car is the only vehicle I have driven in which a violent increase in pressure has nearly no effect, leading me to suspect this could be the "running out of revs" described which is common in NA diesels.

[Rtth84]

driver skills wise, i dunno abt the type R, but my launching is horrible. loads of wheelspin. with 195 tires and 240nm stock (now zhng maybe 280 or more), hard to maintain traction

 

zhng not so low torque leh. ur combo put t-box = 125hp 300nm = lots of torque steer (:

[Cerano]

diesel engines were designed for fuel economy as well as for heavy commercial vehicles, to move heavy loads and many people (buses) easily....they were not meant for performance....

 

it's only until recently, thanks to Euro emission standards, that engineers find it apt to fit a turbo-charger to diesel engines, to meet emission standards.

 

suddenly, horsepower and torque figures surge way pass the petrol alternatives.

 

Modern turbo-charged diesels can outrun an equivalent engine cc NA car (both in terms of acceleration and top speed)....even though the prominent of quick upshifts for diesel engine is still there, thanks to a much lower red-line and tighter gear ratios.

 

i guess the only reason why you'd still go for a petrol powered car is the engine noise it makes (much livelier and you can rev the engine till 6,000-8,000rpm for all you care as compared to 4,000-5,000rpm in a diesel)

 

and as well as a petrol engine is much more refined and quieter at idle....

 

yes but with the move towards FI for petrol, there is no way diesels can match the acceleration from FI petrols

[Mini-itx]

yes but with the move towards FI for petrol, there is no way diesels can match the acceleration from FI petrols

 

Even if FI, Diesel simply still have the advantage for low RPMs. For petrol, the dreaded turbo lag will still be very noticeable.

 

Diesel engines are in no way inferior compared to equivalent petrol ones. A properly designed diesel car can go as fast as a petrol car.

 

[Mini-itx]

at highway speeds your diesel will be out of grunt!!!

 

Not the case for SG high ways..... If you dare to go at 200, by all means. I got no balls to do that because I fear for my license....

[YellowFlash]

yes but with the move towards FI for petrol, there is no way diesels can match the acceleration from FI petrols

 

 

but if its about efficiency, i think diesel engines are more efficient, better mileage, better for normal driving as power band is narrower and makes overtaking a breeze. Btw have u seen the vid on a VW toureg diesel towing a plane? that car has 700nm of torque iirc

 

 

[YellowFlash]

Even if FI, Diesel simply still have the advantage for low RPMs. For petrol, the dreaded turbo lag will still be very noticeable.

 

Diesel engines are in no way inferior compared to equivalent petrol ones. A properly designed diesel car can go as fast as a petrol car.

 

i guess at the end of the day there's no point debating which is better...because i think both has its merits and are designed and built for a different purpose

[Cerano]

Not the case for SG high ways..... If you dare to go at 200, by all means. I got no balls to do that because I fear for my license....

 

ok la

 

autobahn speeds

[Cerano]

Even if FI, Diesel simply still have the advantage for low RPMs. For petrol, the dreaded turbo lag will still be very noticeable.

 

Diesel engines are in no way inferior compared to equivalent petrol ones. A properly designed diesel car can go as fast as a petrol car.

 

hahaha dunno leh.

with SC there will be no turbo lag?

 

anyway diesels can never win a petrol equivalent in 1/4 mile drag races

[Mini-itx]

hahaha dunno leh.

with SC there will be no turbo lag?

 

anyway diesels can never win a petrol equivalent in 1/4 mile drag races

 

Yes, with roots or twinscrew Sc, there will be no lag.

 

As for 1/4 mile race, if everything is the same for both cars except for the engine, diesel cannot win. The weight itself is already a big killer. diesel engines also run out of breath at much lower RPM and a much narrower power range thus if the gears are not meant for diesel, its useless.

 

 

[Mini-itx]

Btw, I have to say one thing. Diesel "like" engines is the future. Conventional petrol engines will die one day.....

 

I meant that engines w/o the need for spark plugs is the future. This is because spark plugs produces rather uneven combustion and efficency is poor.

 

Manufacturers are already researching on high compression petrol engines w/o spark plugs. Petrol is no different from diesel. Upon reaching high temp, the petrol will auto ignite even if there is no spark (just like knocking). Thus instead of having a spark plug to ignite, the A/F mixture will auto ignite under high compression (something like 14-16:1). The car produces more power and uses less petrol.

[YellowFlash]

Yes, with roots or twinscrew Sc, there will be no lag.

 

As for 1/4 mile race, if everything is the same for both cars except for the engine, diesel cannot win. The weight itself is already a big killer. diesel engines also run out of breath at much lower RPM and a much narrower power range thus if the gears are not meant for diesel, its useless.

 

the amount of lag depends on the turbo design/material and also its size relative to engine capacity...ask the GTR owners, they'll tell u the power is very linear and has no lag...similarly a stock evo9 has little or no lag but a the older STIs will experience turbo lag.. Also there is ALS used in rallys to counter turbo lag but it kills the turbo really fast and definitely illegal and irritating..

[Ghostrider]

You should try a modern diesel car....which I find its the way to go.

 

I tried a BMW 320d and the drive was fantastic !! At 1,800rpm...its already developing its max torque of 300Nm....that is slightly lesser than a WRX only (dun forget WRX 330Nm comes in at a heady 6500rpm). It was a step and go car...and with a larger 530i pacing...after a spirited drive...the 320d return 5-6L/100km while the 530i was doing 9L/100KM !!

 

The only downside is that the engine run outta puff at higher rpm...but heck...for daily drive...its very good. Power that you can use is more important...I love it !!

[Cerano]

You should try a modern diesel car....which I find its the way to go.

 

I tried a BMW 320d and the drive was fantastic !! At 1,800rpm...its already developing its max torque of 300Nm....that is slightly lesser than a WRX only (dun forget WRX 330Nm comes in at a heady 6500rpm). It was a step and go car...and with a larger 530i pacing...after a spirited drive...the 320d return 5-6L/100km while the 530i was doing 9L/100KM !!

 

The only downside is that the engine run outta puff at higher rpm...but heck...for daily drive...its very good. Power that you can use is more important...I love it !!

 

my only concern is that diesel engines run outta crunch at 60-80 so even if I win people at traffic light at launch, after that I already lose... And given that nowadays lots can give max tq at 1800rpm too

 

[Cerano]

Yes, with roots or twinscrew Sc, there will be no lag.

 

As for 1/4 mile race, if everything is the same for both cars except for the engine, diesel cannot win. The weight itself is already a big killer. diesel engines also run out of breath at much lower RPM and a much narrower power range thus if the gears are not meant for diesel, its useless.

 

so moral of story, if u want diesel u gotta get manual tranny to maintain the powerband

[Lectrosphere]

eventually. initial the petrol confirm lose. but depends on what one wants.

 

i play with some souped up civics before. the old sir type and new type R. can keep up with them in the initial phase, and my displacement less than the 2.0 type R. eventually cornering and flat out will lose big time la, i'm not kidding anyone here.

 

driver skills wise, i dunno abt the type R, but my launching is horrible. loads of wheelspin. with 195 tires and 240nm stock (now zhng maybe 280 or more), hard to maintain traction

 

hi bro, what ride you on now?

[Ferraricalifornia]

so moral of story, if u want diesel u gotta get manual tranny to maintain the powerband

 

 

that's absolutely correct....

 

that's why many European drivers opt for manual in their Diesel powered cars....

 

not only does it provide fuel efficiency, it's also able to cope with the highway speeds there....

which is around 110kph-140kph cruising....

[Ferraricalifornia]

if you want petrol to combust just by pressurization,

 

a high octane fuel rating will do just that....the temperature caused by compression is good enough to ignite the fuel already, something like jet fuel....

 

you stand 5m away from the jet fuel and you ignite your lighter....the jet fuel will combust into flames....

 

if only diesel engines could be made lighter, their performance figures will be much more superb....the engine wouldn't be bogged down by it's heavy weight alone....