birth of another C55

[c55m8o]

Originally posted by Ashkan's C280
quote:
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I would really like a 3.46 or 3.67:1 for my C43 with LSD.

What have you found out about the ECU adaptation to the new gear ratio.

Jeff.
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3:67 my bad

...argh... geez... ALLL THAT PROVES IS JEFF DIDN'T KNOW WHAT WAS AVAILABLE FOR THAT REAREND PUMPKIN WE HAVE @ THE TIME HE WROTE THAT -- HE HAS SINCE =BOUGHT= IT, AND =OWNS= IT, AND i =SAW= IT WHEN i WAS @ HIS HOUSE, AND TALKED ABOUT WHAT THE RATIO WAS, AND i CALLED THE SALVAGE YARD HE BOUGHT IT FROM SO i ALSO KNOW WHAT IS AVAILABLE, PLUS, i LOOKED IT UP FOR MYSELF ON THE INTERNET TA'BOOT...AND YOU CAN TOO! <grrrr>

Here... (dag nab-it)

From Potomac German Auto @
http://www.mbpartsonline.com/recycled.html

Perform an "Inventory Search" (OEM Recycled Used MB Part)

Select
1998
Mercedes C Class
Ring & Pinion Only

You are returned the sub-selection of:

Select your option
202 Type, C230, Mexico, MT, 3.46 ratio
202 Type, C230, Mexico, AT, 3.27 ratio
202 Type, C230, US, 3.27 ratio
202 Type, C280, 3.07 ratio
202 Type, C43, 3.07 ratio



...from what I learned from both them, and BergWerks (before they closed their doors) minus changing out the whole rear-end assembly, 3.46 is as high as we can go in that rear-end.

So can I ask you...please just freak'n stop?! ...ney, I know what... I'm just going to stop responding... Next I'm going to have to purchase an entire dyno unit so I can scan the manual and post it here too...

[Ashkan's C280]

don't be a jerk... I am sick of fucking hearing it, you have good info and I just backed the info a search came up with... and back to the diffs you guys used the one from 202 Type, C230, Mexico, MT, 3.46 ratio? And you said minus replaceing the entire thing the most you can get is a 3.46, what would you replace it with? Hey man I'm a n00b when it comes to diff changes and gearing, just trying to figure some info out man cut some slack....

Another question jeff and some others ahve the kleeman lsdif I changed the ring and pinion to this c230 3.46 mexican type could I add lsd? And if not what would I have to change in order to add the kleeman lsd and a better diff?

[c55m8o]

Oh, and I'm supposed to edjamacate you now? good one... I recommend you edit and delete that opening and incoherent shit you just posted. It's called humility. Get some; much better then being arrogant, after being so wrong.

...consider this ... that info you so confidently refer to from a search... GEE, didn't it say something else too ?[i.e. "3.46"] ...and wasn't that the very same thing I confirmed to be the actual case?

Now, after reading my post stating the actual reality, you had two choices --
- be like all the others that read it, accepted it, and went on with life ...
- or choose the other of the two possibilities mentioned for no particular other reason for backing it then it being opposite to what someone else [I] said, as it's something you can pick-up on and be argumentative with ... Ya just missed the point you "should" only choose an argument you actually have a reason for backing ; NOT backing it just because it is the opposite to what someone else said.

...call me RodneyD.

[coolcarlskic43]

Originally posted by J Irwan


Bottom line what I am trying to say

while stock E55 running 280 rwhp and your C55 conversion running 298 rwhp that doesn;t mean your crank hp is higher.

Regardz,

I don't see how you feel that the gearing will affect HP. E55's stck dyno from 285-293hp as well with the 2.82 rear diff.Same #'s as Steve's and my car pre chip upgrade!Same thing with the CLK55 which has a 2.82 rear end.All 3 cars have dynoed the same #'s in spite of them having the diffrerent rear end gear ratios.

[c55m8o]

Originally posted by coolcarlskic43
I don't see how you feel that the gearing will affect HP. E55's stck dyno from 285-293hp as well with the 2.82 rear diff.Same #'s as Steve's and my car pre chip upgrade!Same thing with the CLK55 which has a 2.82 rear end.

Thanx for reminding me of that Carl. That's right... When I did my dyno, I did it chipped (soup'd up E55 program) two or three times (peak HP was 306, but a small peak so I don't really count it or usually mention it). Then had the C43 maps loaded and lost about 30 hp & ft-lbs ; then had the Stock E55 program loaded and was in the high 280's - low 290's like Carl mentions, inline with measured E55's. Chipping the E55 program yeilded about 9 - 16 hp in different areas of the HP curve.

[sig425]

heh that potomac place has an e55 motor too bad is $10k Yikes!!

[c55m8o]

Originally posted by sig425
heh that potomac place has an e55 motor too bad is $10k Yikes!!

yep ... all salvage yards I found (3) over the years that had them always wanted $10K - $15. Wouldn't budge. ...like a leprechan (sic) and their gold...

[sig425]

well that settles that. I thought the total bill would be like $11k installed. I can install the SC but not a motor.

[c55m8o]

Originally posted by sig425
well that settles that. I thought the total bill would be like $11k installed. I can install the SC but not a motor.

I won't disagree; just want to add tho, it would/could be $11K (or easily less if the engine doesn't need reconditioning), if you get the motor from Norman or directly from someone who wrecked their car like Carl did; getting the engine for a more realistic $6K range. ...I waited some 4 - 5 years because of that price before I stumbled on Carl, who then put me in touch with Norman after I was bitching about the engine prices to him. Just thought I'd mention that ; but w/o a doubt, there's some luck & timing involved in trying to source the engine from someone other then a salvage yard. Doing a S/C is =much= quicker and easier.

[sig425]

lol you are killin me. Just when I think I have made up my mind you throw a wrench in there. It prolly doesnt make much difference as I have to sell my bike or my rx7 before I can do anything. The nickle dime repairs to get the car to 100% are more like $1 to $5 on this thing. So my slush fund is about gone now and I have not replaced the suspension bushing yet.

[J Irwan]

Originally posted by coolcarlskic43
I don't see how you feel that the gearing will affect HP. E55's stck dyno from 285-293hp as well with the 2.82 rear diff.Same #'s as Steve's and my car pre chip upgrade!Same thing with the CLK55 which has a 2.82 rear end.All 3 cars have dynoed the same #'s in spite of them having the diffrerent rear end gear ratios.

you're missing my point.

What I was trying to say gearing will affect the hp you put down on the rearwheel.

Don't get confused with cranck hp.

I was just saying...that if you use different rear end than factory, then you do further modification your correction factor to get cranck hp estimate will be different.!!


I am not trying to say anything different.. (please read my post)
The reason I was posting because I sensed some confussion regarding estimated cranck hp from the same engine that is being put on the different car with different rear end ratio 3.07 vs 2.82 which both has the same exact geaing (same exact gearing for 1st, 2nd, 3rd, ...5th).

CLK55 W208 and E55 W210 have the same 2.82 rear end.


I have a lot of buddies back in the old days of E36 M3.
Changing to taller rear end result in faster acceleration (stock engine - no mod) and when you dyno , it will have higher rearwheel number.... (everything I said, there is a formula...)

thats why perfect gearing will get you far..

Take a look E46 M3 vs C5 corvette vs C32/C55.

E46 M3 will have the least hp and torque, while C5 corvette have the most hp and torque and the lightest of all.

But why E46 M3 can keep up.... ..its the gearing..!!
BMW did a good job on gearing no doubt about it.



I've seen too many people got so hang on achieving additional hp at the engine, but not try to minimize drivetrain loss....

A long time aga at benzsport (now bnzsport) I was exploring option to change my rear end to achieve this...
But I didn't pursue at the time, since I don't have a good MB mechanics that I can trsut to do the swap in my nearby area.


If you look at one of the best bang for the buck for E46 M3 and E39 M5 is changing rear-end to taller one. This will allow you to transfer more of that power to the ground....which result in faster acceleration..


Same reason speedybenz want to swap to taller rear-end. Faster acceleration !




Regardz,

[Ashkan's C280]

so what could we change to? And you're talking about a change of the entire rear diff?

[coolcarlskic43]

Originally posted by J Irwan
you're missing my point.

What I was trying to say gearing will affect the hp you put down on the rearwheel.

Don't get confused with cranck hp.

I was just saying...that if you use different rear end than factory, then you do further modification your correction factor to get cranck hp estimate will be different.!!


I am not trying to say anything different.. (please read my post)
The reason I was posting because I sensed some confussion regarding estimated cranck hp from the same engine that is being put on the different car with different rear end ratio 3.07 vs 2.82 which both has the same exact geaing (same exact gearing for 1st, 2nd, 3rd, ...5th).

CLK55 W208 and E55 W210 have the same 2.82 rear end.


I have a lot of buddies back in the old days of E36 M3.
Changing to taller rear end result in faster acceleration (stock engine - no mod) and when you dyno , it will have higher rearwheel number.... (everything I said, there is a formula...)

thats why perfect gearing will get you far..

Take a look E46 M3 vs C5 corvette vs C32/C55.

E46 M3 will have the least hp and torque, while C5 corvette have the most hp and torque and the lightest of all.

But why E46 M3 can keep up.... ..its the gearing..!!
BMW did a good job on gearing no doubt about it.



I've seen too many people got so hang on achieving additional hp at the engine, but not try to minimize drivetrain loss....

A long time aga at benzsport (now bnzsport) I was exploring option to change my rear end to achieve this...
But I didn't pursue at the time, since I don't have a good MB mechanics that I can trsut to do the swap in my nearby area.


If you look at one of the best bang for the buck for E46 M3 and E39 M5 is changing rear-end to taller one. This will allow you to transfer more of that power to the ground....which result in faster acceleration..


Same reason speedybenz want to swap to taller rear-end. Faster acceleration !




Regardz,

I can not see how that has anything to do with HP.I can see that with the 3.07 rear vs the 2.82 rear the car with the 3.07 will spin the rear wheels faster as a result of the shorter gear ratio.

I cannot see how if you take an E55 with a 3.07 diff and an E55 with a 2.82 diff,place them both on the dyno in 4th gear how the dyno would show one of the cars putting down more hp to the wheels.

I think the car with the shorter gearing would put the same whp down but the difference would be that the actual axles would spin much faster and for a shorter time giving you quicker acceleration.I can't see how this necessarily increases HP to the wheels.


However, what will also happen in the long run is that the car with the same exact crank hp with the longer gears will also have a much higher top speed and at some point down the road,and even further down the road better acceleration potential at atmospheric speeds.

Because the longer gearing will also allow (x) car to stay in the sweet spot alot longer.This is also why guys that use F/I on the E36 cars opt for taller gears because the power will be stretched out over a wider range.This does not increase their wheel hp.


Perhaps someone can chime in on this.I sort of see your point somewhat but for some reason the dyno is making up for the gear ratio differences.How does the diff gear ratio's also equate to drivetrain loss?

Also 3.07=shorter.2.82= taller! Shorter for faster acceleration taller will result in less revolutions which = slower acceleration.

[c55m8o]

Originally posted by J Irwan
you're missing my point.

What I was trying to say gearing will affect the hp you put down on the rearwheel.

Don't get confused with cranck hp.
...

OK, sorry then. I'm with you on that.

Ya know, though, surprisingly, that vehicle performance simulation and optimization program I've fallen in love with, CarTest2000, had some interesting things "to say" about shorter gears in my car. It's got this really great "optimization" capability that maximizes performance varying one set of parameters, while you hold certain other parameters fixed... (and it combines measured wheel HP with rated flywheel hp & torque figures, takes into account various losses, to give you a realworld torque and hp engine curve it runs the optimization with) ... So hold the tranni gears fixed, then change the rear and do some 0-whatever mph passes, or 1/4 mile passes (or let it do the optimizations itself instead of you choosing gears)... and...

...long story short, something I read years ago from someone who wrote a great article on HP vs torque and the importance of each, proved true:
- all things being equal, it's better to make torque @ high rpm then low rpm because then you can take advantage of =gearing=.
- and as Carl has said, the MBs "shoot their load early" when it comes to torque... where you see my torque is @ 325 in the mid 4K rpm, but drops to near 225 near redline ... i.e. the 5.4L does =not= makes its torque @ high RPM

... well it turns out if I were to go to a higher rear gear ratio (w/o rasing redline), I'd actually be =increasing= times for 0-60 and 1/4 mile... ; i.e. decreasing performance .... bummer. Going lower is actually a different story with the 5.4L engine, because of the low torque peak ... After all, as you're =only= using the low rpm torque peak in 1st gear, you want to maximize the pull 1st gear gives you ; i.e. longer gears. I should do some screen captures of 0-60 or 1/4 miles with different rears. That was pretty shocking, but it sure makes sense in retrospect.

The way Jeff has his car breathing tho, his car would be a different story. Actually, if Jeff were to dyno his car and get me the table data, I could do some optimizations (or, he could spend $40 & buy it himself; it's well worth the cost )

[tho in the case of the BMW you make mention of ... yes it had higher raw force #s @ the wheel, but calculated rwhp shouldn't change, else someone was doing something wrong ; same idea of dyno'ing your car in 3rd, then dyno'ing it in 4th -- that's basically the same as dramatically changing your rear diff but keeping the tranni in the same gear -- the dyno will report the =same= HP & torque numbers measured in 3rd as when measured in 4th (ignoring possibly some more tranni losses in 3rd) ]

[c55m8o]

Originally posted by coolcarlskic43
...
Because the longer gearing will also allow (x) car to stay in the sweet spot alot longer.This is also why guys that use F/I on the E36 cars opt for taller gears because the power will be stretched out over a wider range.This does not increase their wheel hp.

Perhaps someone can chime in on this.I sort of see your point somewhat but for some reason the dyno is making up for the gear ratio differences.How does the diff gear ratio's also equate to drivetrain loss?

Also 3.07=shorter.2.82= taller! shorter for faster acceleration taller will result in less revolutions a slower acceleration.

Yes, 100% on those accounts. I recommend everyone into this invest in CarTest2000 ... program's awesome.

The only thing I'd say counter to that is when a car is "torque-deficient", but torque stays flat or even rises up to readline, and redline is into the 7Ks or higher, it's =better= to run with shorter gears (higher ratio like Carl's saying) ... like the stock E46 M3 as an example.

[coolcarlskic43]

And from my understanding the differential is basically the TQ multiplier not the hp multiplier!Which we know affects the pwr over a given rpm range!

[J Irwan]

Originally posted by coolcarlskic43
And from my understanding the differential is basically the TQ multiplier not the hp multiplier!Which we know affects the pwr over a given rpm range!

sorry about the taller vr shorter gears...

I was mixed about that and I realized that I after I re-read my post.


Now about hp vs torque just so you know...
HP is derived from rpm x torque.. (I don't remember the formula but that is the general concept).

Just looking at your statement if rear-end affect torque (making it higher at rear wheel) it will also increase the rearwheel hp.


Regardz,

[J Irwan]

Originally posted by c55m8o
OK, sorry then. I'm with you on that.

Ya know, though, surprisingly, that vehicle performance simulation and optimization program I've fallen in love with, CarTest2000, had some interesting things "to say" about shorter gears in my car. It's got this really great "optimization" capability that maximizes performance varying one set of parameters, while you hold certain other parameters fixed... (and it combines measured wheel HP with rated flywheel hp & torque figures, takes into account various losses, to give you a realworld torque and hp engine curve it runs the optimization with) ... So hold the tranni gears fixed, then change the rear and do some 0-whatever mph passes, or 1/4 mile passes (or let it do the optimizations itself instead of you choosing gears)... and...

...long story short, something I read years ago from someone who wrote a great article on HP vs torque and the importance of each, proved true:
- all things being equal, it's better to make torque @ high rpm then low rpm because then you can take advantage of =gearing=.
- and as Carl has said, the MBs "shoot their load early" when it comes to torque... where you see my torque is @ 325 in the mid 4K rpm, but drops to near 225 near redline ... i.e. the 5.4L does =not= makes its torque @ high RPM

... well it turns out if I were to go to a higher rear gear ratio (w/o rasing redline), I'd actually be =increasing= times for 0-60 and 1/4 mile... ; i.e. decreasing performance .... bummer. Going lower is actually a different story with the 5.4L engine, because of the low torque peak ... After all, as you're =only= using the low rpm torque peak in 1st gear, you want to maximize the pull 1st gear gives you ; i.e. longer gears. I should do some screen captures of 0-60 or 1/4 miles with different rears. That was pretty shocking, but it sure makes sense in retrospect.

The way Jeff has his car breathing tho, his car would be a different story. Actually, if Jeff were to dyno his car and get me the table data, I could do some optimizations (or, he could spend $40 & buy it himself; it's well worth the cost )

[tho in the case of the BMW you make mention of ... yes it had higher raw force #s @ the wheel, but calculated rwhp shouldn't change, else someone was doing something wrong ; same idea of dyno'ing your car in 3rd, then dyno'ing it in 4th -- that's basically the same as dramatically changing your rear diff but keeping the tranni in the same gear -- the dyno will report the =same= HP & torque numbers measured in 3rd as when measured in 4th (ignoring possibly some more tranni losses in 3rd) ]

Whewss.... finally I am glad you see what I am trying to say. (I almost gave up ).

I agree with what you said, that the torque on E55 engine is available on low rpm and they could use the taller gear (2.82 as opposed to 3.07) to get the optimum sweet spot on the power band.

I have to disagree with you.
However if you switch the rear-end from 3.07 to 3.45 you will gain better 0-60 time and 1/4 miles times. After all 3.07 is not that extreme at all. Now if you go extrem from 3.07 to say 4.21 that you might still be gaining quicker 0-60 time and slower on 1.4 miles.
As I said 3.07 is still not optimum. I think the reason MB choose 3.07 to be the most aggressive rear-end on their car is to preserver MPG number. (everything is design and fitted for a reason, after all not everyone who buy AMG is willing to put up with poor MPG)


But like everything else, a lot of thing is stock form from exhaust setup (noise vs free flow), chip (ignition timing and fuel map) to gearing is setup that way for a reason. To compensate for all kind of driver / consumer. for minimum noise optimum fuel efficiency/optimum mpg.

Many has switch to shorter rear-end to be on the more aggressive side. But at the same time you don't want it to be too short so that you lose some of the high-end performance (decreased top speed, etc).
If MPG if not a concerned I am sure shorter gearing will be faster.

The same reason you see CLK55 W209 and C55 W203 use 3.07 rear end. 0-60 4.7 sec
And CLK55 W208 2.82 0-60 5.0 sec (All 3 of these cars has the same exact gearing for 1st -5th)


Also On E36 M3 F/I only a few people who gone extreme hp will opt for taller gear (2.82 instead of 3.45). But most of them switch to more aggressive ratio to compensate on the low end turbo lag.
Many of these cases there don't have extremee hp (such as 800+) to go for more relaxed rear-end.


I forgot where I read it before , there was a lot of good information on engine performance that discuss why smaller displacement could have maintain the torque curve for a longer period of time than the bigger displacement.
While bigger displacement have more at the beginning but it also dropping at higher rpm which why you see all AMG redlines are not so high compare to S2000 2.0L (240hp) and E36 M3 euro 3.0L (286hp)

PS: You can theorized all the stuff I posted. But I sat in one of my buddy car that only has rear-diff upgrade and it definitely pull faster. And reach the stop limiter (155 mph) faster too.


Regardz,

[c55m8o]

hold your opinion until you see it calculated out though (I'm tell'n ya, get CatTest2000 )... I'd say after seeing the runs, you shouldn't underestimate the impact such a drop-off in torque @ high RPM can have, and how that works against raising the rear-end gear ratio, too much. Hey, I was a =die-hard= advocate of converting my rear to 3.45:1 ; that is, was, but not with this engine's torque rolling off as it does @ high rpm .

yes, CarTest2000 also says 3.07 is pretty much the optimal rear. What I was saying was it also proves out that going longer (to 2.82:1) would be better with that engine then going to shorter gearing (to 3.45:1).

BTW, raising the gear ratio is not all upside ; there's trade-off there too, since the shift occurs a few mph sooner in each gear when you have shorter gears; (I hope I can explain this right) ... for the few mph difference between where it shifts with the shorter gears, compared to where it used to shift with the longer stock gears, acceleration is actually =lower= because you have less torque multiplication working for you, as you're in the next higher gear. Less "F", same "m", less "a". So that actually takes more time to get through that few mph range, then with the stock gears. Of course, for all the rest of the mph range in that gear, acceleration is quicker with the shorter gears. However it's important to realize there's some given back through the RPM range, so it's not all up-side.

This is also why I say going to shorter gears should be accompanied with a raise in the redline as well (which of course is easier said than [safely] done). [ Please read my analysis on this subject here ... ]

If this is done, there is no trade-off, as
a) you have more pull in each gear @ the tire's contact patch from the shorter gears...
b) since you have a higher redline, you can now pull longer (to a higher RPM) then you did before, and you will not have to shift out of the gear sooner because of the shorter gear.

I'm really not sure if this is clear enough. If you read my analysis on this, it should be clearer. Also, please read my reply to ironchefc43 just under the one I'm linking to, regarding the gains if you raise the redline to accompany the shorter gears.

[coolcarlskic43]

Originally posted by J Irwan
sorry about the taller vr shorter gears...

I was mixed about that and I realized that I after I re-read my post.


Now about hp vs torque just so you know...
HP is derived from rpm x torque.. (I don't remember the formula but that is the general concept).

Just looking at your statement if rear-end affect torque (making it higher at rear wheel) it will also increase the rearwheel hp.


Regardz,

The engine TQ is multiplied by the differential to spin the rear wheels at a certain revolution.Then you have to apply a formula based on all of that.

I strongly dissagree about the fact that having 4.11 gears in the rear of my E36 M3 will show an increase in rear wheel hp as opposed to having a 3.23 diff on the car.The ex. you gave about the C5 and the E46 M3 does not equate to the E46 M3 putting down similar or more hp to the wheels than the C5 because of the diff.No offense but that does not make sense,if that's what you are saying.

Alot has to do with the characteristics of the motor and weight + rear axle ratio of the two vehicles .

The two vehicles are very close when it comes to rwhp 270-280(M3) vs rwhp 295(Corvette).This is not because of the differential.How they run against each other off of the dyno can be attributed to weight,engine character,and gearing. They are also close in rwhp.

[c55m8o]

BTW, J, I still wish to come to some clarity on the subject... I think I put my finger on the whole back and forth. I finally realize we still continue to use the same terminology, but are talking about slightly different things when we say rw hp (or rw torque) ... I'll annotate this with a visual aid <grin>.

So, please note my HP/Torque graph I posted in the middle of this thread ... actually, I'll post it here...

(btw, this is the stock E55 chip program. DYNORUN.001 done with the mod'ed E55 program peaked @ 306hp, but I don't have it graphed like this.)

So to understand, I'll ask, how is it the HP & Torque graphs when the car is in third, is measured and rendered to the same values @ the same RPM as when the car is in fourth? I know that this graph represents hp (& calculated torque) to the rear wheels, not crank. (any why I'm saying "dynos normalize", to =remove= gearing from the equation).

I also know though, you're saying "hp to the wheel is greater the shorter the rear" ... well yes, but I guess I'd like to call that linear force @ the tire's contact patch, not rwhp. But isn't it true that's also the case the lower the tranni gear? i.e. more force @ the tire's contact patch in 3rd vs. 4th, and 2nd vs. 3rd, and 1st vs 2nd?

So what I'm trying to understand, is it you are saying that the graph above is =not= a rear wheel hp and rear wheel torque graph? What is it then / what would you name it? I don't think that's the case. And I know it's not "crank" hp & torque. So what I'm having trouble with is, if that graph shows rwhp, how can we call what you're saying -- that =includes= gearing in the equation and any resulting graph if it were to be graphed -- rwhp too? (actually, CarTest2000 does have a particular name for that, but that's on my laptop and I'm not up for going to get it, plug it in and turn in on to see @ the moment... ).

Therefore, perhaps, wouldn't it be better to call the force being applied the the tire's contact patch that is a result of including gearing in the equation which you keep using, =effective= HP and =effective= torque? ... it is the =effective= torque applied to the tires' contact patch, as a result of torque multiplication when taking gearing into account as well.

So I finally get to the point, that I guess it all boils down to is it generally accepted to call it rwhp, and include gearing? I personally, thought it was not ; that rwhp is the engine crank torque, passed through the drive-train and tires, and the rotating torque at a speed (a.k.a. HP) is measured, and normalized to remove gearing ; and if gearing was included, it should be called something else (i.e. effective rwhp).

thoughts?

[c55m8o]

Originally posted by J Irwan
HP is derived from rpm x torque.. (I don't remember the formula but that is the general concept).

Just looking at your statement if rear-end affect torque (making it higher at rear wheel) it will also increase the rearwheel hp.

The linear relationship is :

HP = (Torque * RPM) / 5252

HP is said to be derived from Torque. I think the scientific way to look at it is (and I might be wrong, sorry if so), engines produce torque, not power ; once the output of the engine's torque is applied to an eternal device and coupled to something that produces motion, that is said to be power.

somewhat confusing is , chassis dynos measure HP and calculate Torque.

I believe engine dynos measure Torque, and calculate HP tho.

[coolcarlskic43]

Originally posted by J Irwan






Paragraph 1.
Also On E36 M3 F/I only a few people who gone extreme hp will opt for taller gear (2.82 instead of 3.45). But most of them switch to more aggressive ratio to compensate on the low end turbo lag.
Many of these cases there don't have extremee hp (such as 800+) to go for more relaxed rear-end.

Paragraph 2.
I forgot where I read it before , there was a lot of good information on engine performance that discuss why smaller displacement could have maintain the torque curve for a longer period of time than the bigger displacement.
While bigger displacement have more at the beginning but it also dropping at higher rpm which why you see all AMG redlines are not so high compare to S2000 2.0L (240hp) and E36 M3 euro 3.0L (286hp)

Paragraph 3.
PS: You can theorized all the stuff I posted. But I sat in one of my buddy car that only has rear-diff upgrade and it definitely pull faster. And reach the stop limiter (155 mph) faster too.


Regardz,

I disagree with you on paragraph 1.READ:http://forums.bimmerforums.com/forum...ight=3.38+diff The guy CRISTIAN makes some very good pts.


I disagree with you on paragraph 2.

This is not true of all bigger displacement motors.Alot of it has to do with the way the bigger displacement motors internals are designed(head,#of valves,crankshaft esign,rods) The new AMG 6.3L V8 will rev beyond 7000 rpm's and make 503hp and 465ftlbs of TQ.Most of the TQ(369) will be available from 2k up.I guarantee you they will not put a radically shorter gear ratio in the car especially because it has so much TQ down low.This is the advantage of bigger displacement plus the fact that the motor now will be a 4 valve per cylinder V8 vs the old 3 valve per cylinder V8. It will be capable of making more hp at higher rev's because it can now breathe better.I guarantee you this will have nothing to do with the diff gearing also providing more hp but will kind of decrease the TQ compared to the older M311 S/C E55 engine.Also think of the new 10 cyl 5.0L M5 motor.Bigger displacement,multi valve head,more hp,more TQ but less than the AMG 6.3L because as MB always does,They go with bigger displacement.


I agree with you on paragraph 3.

The shorter gearing you will get faster acceleration(N/A) but it does not mean it's because of an increase in HP to the wheels.It also means that you run out of usable pwr quicker over the whole rpm range and bang! here comes the next gear shift just to pick back up the power and get back into the sweet spot.This also negates some of the usable power when you are driving a turbocharged vehicle. Finally ,as the speeds get higher there will be no more advantage for the shorter geared car.

P.S. the 2003-2005 CLK's have 2.82 rears not 3.07 which you mentioned above.

[coolcarlskic43]

Steve,please PM me or send me your tel# via MBworld and also email! Thanx! Here I thought I'd help out! http://www.mbworld.org/forums/privat...m&userid=13079

[c55m8o]

Originally posted by coolcarlskic43
Steve,please PM me or send me your tel# via MBworld and also email! Thanx! Here I thought I'd help out!

I'm hurt that I was deleted out of your cellphone... # was sent.
(that link formatted to my account was pretty kewl)