Mid range torque
Discussion
Julian64 said:
Okay, and I know I'm going to regret this. But for the otherwise silent majority that read these type of threads and are just quietly amused by the intensity of feeling and interest they generate, especially the crown of most powerful Cerb, I have a question which sums up my interest. Don't want any sort of rolling road crown, but it seems that things have progressed far enough that a fairly confident 400bhp can be reached from the 320-350 bhp that most standard 4.5 cars are actually running. Not interested in 1-2bhp gains, will be happy with anything over 380 bhp.
How close are we to a bolt on kit supplied by one of the big names, that gives an optimum Cerbie power. (I guess I'm right in thinking that this will comprise induction pipes and a ECU mapped by a specialist for the car.)
In an effort to get away from the debate over dyno differences, I think Julian64's comment above, touches on what really matters to those modifying their car. Most people actually modify their car to make it a more enjoyable drive. An absolutely mental top end is clearly a good wheeze, when you get to use it, but it's far from the whole story.
What I think makes mapped cars better is their smoother delivery. This I think, is due to more consistent and larger torque spread in the mid range and improved part throttle response. Something that seems to have gone largely unnoticed in the recent debate over peak power, is the torque spread Tim of ACT's car demonstrated at SRR on the weekend.
ACT said:
2800 rpm it makes 315 lb ft, 3300 rpm= 345 lb ft, at 4000 rpm= 365 lb ft, 5200 =373 lb ft.
What I'm interested in opinions on, when we see some graphs from the weekend, is how their torque curves compare. My contention is that torque generated in the manner above, is actually of more useful in the real world, than just a screaming top end. This is only my opinion of course, so what say you, members of the forum? Of particular interest to me is what the silent majority, such as Julian64. Especially those of you considering mods in the near future think. Is what I'm describing what you actually want, or am I way off beam?
Cheers,
Steve.
>> Edited by Steve_T on Monday 27th February 10:36
Steve_T said:
Okay, and I know I'm going to regret this. But for the otherwise silent majority that read these type of threads and are just quietly amused by the intensity of feeling and interest they generate, especially the crown of most powerful Cerb, I have a question which sums up my interest. Don't want any sort of rolling road crown, but it seems that things have progressed far enough that a fairly confident 400bhp can be reached from the 320-350 bhp that most standard 4.5 cars are actually running. Not interested in 1-2bhp gains, will be happy with anything over 380 bhp.
How close are we to a bolt on kit supplied by one of the big names, that gives an optimum Cerbie power. (I guess I'm right in thinking that this will comprise induction pipes and a ECU mapped by a specialist for the car.)
In an effort to get away from the debate over dyno differences, I think Julian64's comment above, touches on what really matters to those modifying their car. Most people actually modify their car to make it a more enjoyable drive. An absolutely mental top end is clearly a good wheeze, when you get to use it, but it's far from the whole story.
What I think makes mapped cars better is their smoother delivery. This I think, is due to more consistent and larger torque spread in the mid range and improved part throttle response. Something that seems to have gone largely unnoticed in the recent debate over peak power, is the torque spread Tim of ACT's car demonstrated at SRR on the weekend.
ACT said:
2800 rpm it makes 315 lb ft, 3300 rpm= 345 lb ft, at 4000 rpm= 365 lb ft, 5200 =373 lb ft.
What I'm interested in opinions on, when we see some graphs from the weekend, is how their torque curves compare. My contention is that torque generated in the manner above, is actually of more useful in the real world, than just a screaming top end. This is only my opinion of course, so what say you, members of the forum? Of particular interest to me is what the silent majority, such as Julian64. Especially those of you considering mods in the near future think. Is what I'm describing what you actually want, or am I way off beam?
Cheers,
Steve.
>> Edited by Steve_T on Monday 27th February 10:36
Steve, I have to agree with you here. I have been playing with cars for 17 years now, and albeit with lower power cars, you can generally get the top end power, by changing cam profiles, ingniton and timing with fueling, we all know this. Ususally to get max power and top end figures, you have to sacrifice power elsewhere, usually at the bottom or mid range. To get both max top end and mid range with a good delivery from the bottom is a true feat.
Great, get the topend MAX BHP and have to rev the nuts of the engine to get there, have a hole/dip in the torque pattern with a decatt in the mid range, and maybe a lumpy running upto 2500-3000 rpm. Or have slightly less TOP END, maybe 10 BHP less or 15 even, have a really nice SMOOTH power delivery, with no dips or rough patches, and dont have to rag the ass off the engine to get there.
Whats do you want. MAX POWER, or, a really nice car to drive, and have the power in every gear, at the touch of a peddle??
Remember, there will alway be someone chomping at your heals for the all important MAX POWER tittle, or is it a case that circa 400BHP for a road car is just not enought for some people. It is very easy to get caught up in figures.
Mr F
Mr Freefall said:
To get both max top end and mid range with a good delivery from the bottom is a true feat.
I've been wondering for a while now on how you could measure this. My feeling is that the area under the torque curve on a dyno plot is perhaps a better measure of modifications. For instance if you could pickup 30 lbft of mid rpm torque between say 2-4k rpms through a given mod, but your peak power and torque remain unchanged, I'd think it's still worth going for. What do you reckon?
Steve.
Talking of mid-range, I notice from Mad Mark's graph on the other place that his torque curve has a drop in it through 3500-4500 rpm, and mine does too.
Is this an inevitable effect from the standard mapping? "Do they all do that"? Just interested, as looking at my graph it seemed an obvious "room for improvement"
(I originally put something like this one the other thread, but I think it got lost among the gear debate...(unless no one knows))
Is this an inevitable effect from the standard mapping? "Do they all do that"? Just interested, as looking at my graph it seemed an obvious "room for improvement"
(I originally put something like this one the other thread, but I think it got lost among the gear debate...(unless no one knows))
It's hard to say if you can remove the hole altogether by simply remapping, as it may have a number of possible causes. These reasons would also vary from car to car. There's defnitely a big improvement to be had in simply mapping the car. I have a friend who runs the Emerald system on his car and he too reports improvements over standard, so mapping is definitely worth it. However I witnessed useful additional torque gain in the mid range, when the original ACT induction kit was fitted to my car and it was already mapped at this stage. Similarly I know Tim from ACT gained significant mid range torque through his new exhaust system.
Steve.
>> Edited by Steve_T on Monday 27th February 13:30
>> Edited by Steve_T on Monday 27th February 13:31
Steve.
>> Edited by Steve_T on Monday 27th February 13:30
>> Edited by Steve_T on Monday 27th February 13:31
Given nobody has changed cams yet, then remapping will just gain you all power that was "missing" in the first place; i.e. there is no reason to sacrifice mid range torque for top end! You're just getting the mapping closer to ideal (which is not hard on the 4.5 it seems!). All cerbs seem to have a kinky torque curve, but then this makes the power delivery more exciting by appearing as a rush of power. Technically, you could measure the area under the torque curve above the revs you may care about, say 4k.
nelly1 said:
Torqueing of talk, and before you V8 boys winge too much about 'a hole in the middle', check out Marks' graph compared to my Tuscan with its' measly 6 cylinders.......
I haven't driven a Cerb. yet but I reckon that's one hell of a kick up the ass!!!!
Nelly, I have drive both, and had a 4.0 Red Rose T350c. I can tell you that the speed six is more progressive, but the AJP is an instant kick from 2500 rpm. This is why the AJP seems so brutal, instant torque, with BHP at the top end when the torque is starting to tail off.
With the Speed six the torque and BHP are quite liniar (spl) and once you hit 4000 the power is there.
Only way I can describe the difference is the the AGP kicks you there (pushes) and the Speed 6 Pulls you there (like being pulled up the power band). The two engines are really quite different. IMHO, the Speed six feels like you are in more control, but at 400BHP we all know that that is a myth if you get the delivery wrong.
Mr F
When Paul remapped mine, I specifically wanted torque at lower speeds....running your car @ 190+MPH is fine, but only happens very occassionally!
Now my car pulls through all gears all the way, making it more useable/drivable, no pinking or juddering. I may have lost 5MPH @ the top end, but after 3 years I still have not had it above 145, so I won't be missing that!
K1 CERB
Now my car pulls through all gears all the way, making it more useable/drivable, no pinking or juddering. I may have lost 5MPH @ the top end, but after 3 years I still have not had it above 145, so I won't be missing that!
K1 CERB
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