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C280Sportster
10-15-2003, 06:07 PM
Since we have some engine experts here I'd though I would ask you guys something.

While reading a review of the 2004 G35 cars I noticed something weird. Most of us know that the coupe has 20 more HPs, but the Coupe also has 10 more pounds of torque.

"Though the G35 comes with just one engine, it should satisfy all but the most power-hungry drivers. This smooth-revving 3.5-liter V6 makes 260 horsepower and 260 pound-feet of torque in the sedan, and 280 hp and 270 lb-ft of torque in the coupe. Most other four-door cars in this class average around 220 hp, meaning that the G35 is one of the fastest sport sedans available for less than $30,00"

From:

http://www.edmunds.com/new/2004/infiniti/g35/100330765/review.html?tid=edmunds.h..reviews..2.*


So, I thought it had a better intake and exhaust, which would raise the HP, but can those "mods" increase torque also ?

And by that much ?

Of course they could have just de-tuned the 4 door at the computer chip.


Why do I ask ? What I have planned for my car is C43 dual intake, new exhaust (I'm watching the C43 project carefully), evo sport UD pully(s), and a few of speedy's recomendations. I'm trying to guess how much HP and torque I could have. (I'm looking for 230 HP and 230 ft-lb torque, I know I'm dreaming...and BTW a SC is out of my reach right now. If I did SC, I want to do over a tuned up engine anyway.)

speedybenz
10-15-2003, 09:27 PM
C280Sportster,

The G35 most likely has some cams that do not have the same lift as the Z-car. I would guess that is the bulk of the change. But intake and exhaust also could account for the rest of the power loss.

I do not think your 230 Hp dream is out of bounds. You will need to look at the heads and engine internals such as pistons, crankshaft and bearings. I think that 250Hp is attainable if you can raise the rpm limit which would be safe given the short stroke of the V-6.

Jeff

98_Benzo
10-15-2003, 11:41 PM
Hey Sportster -

Look at it this way, you have the same engine block in your car as does the C36. The C36 has, what 274 hp? All you need to do is bore out the cylinders, put some nice racing pistons in, redo your cam and do a couple other little things and you can easily be over the 230 mark (AT THE WHEELS!!).

98c43amg
10-16-2003, 07:15 PM
Originally posted by C280Sportster
So, I thought it had a better intake and exhaust, which would raise the HP, but can those "mods" increase torque also ?


I guess the answer is in knowing what Torque is. This is a sort of hobby of mine, and I've written a lot about it. I'll save you all from my repeating that, but I'll provide links @ the bottom.

As an introduction:

HP = Torque at a rate of speed.

The [T H E] formula for calculating Horsepower is
HP = Torque * RPM / 5252

Put another way, Horspower is just a derivation based on Torque and its relation to RPM. From that you may notice:

1) HP =always= equals torque at RPM 5252. If you ever see a HP/Torque graph using the same vertical axis for both, and they don't cross at 5252, the person who graphed it is plain wrong.

2) There's two ways to increase HP.
2a) Raise the Torque.
2b) Raise the Redline.

So to answer your question, yes the mods did directly alter [increase] the torque, which in turn increased HP. However, they may have also made another mod, say to the heads with stiffer springs, that allowed for a slightly higher redline (and don't ever let anyone tell you that's not one of the most important aspects of an engine). That would increase the HP. Or you'd get the same results if they altered the torque curve to produced more torque at higher RPM, near or at redline.

Another very important point to know is [and I digress], acceleration is directly related to torque curve, not power. Remember
F = m*a
... Force equals mass times acceleration ... Torque twists the wheel. And that in turn becomes a linear Force transferred at the tires contact patch to the road. Since mass is constant, that produces acceleration in direct relation to the torque curve, times the amount of torque multiplication gained from the the drivetrain's gearing in each gear.

Like I said, I've written a good deal on this topic before, so I'll save everyone from that here. But if you'd like a little edjamacation on the whole HP, Torque, Acceleration, Gearing thing and how they all interact, here are a couple of links. After this first one below [which I didn't write], they have other links in them more info. They were very enlightening to me.

If you read nothing else, read this. (http://www.vettenet.org/torquehp.html) I had to read the part about "better to make torque at high RPM that low because then you can take advantage of gearing" a few times before it really clicked. Then I finally understood, how a car with just 265 ft-lbs of torque -- much less than my C43 -- but with a redline of 8000rpm (the BMW M3 if you haven't guessed), can be so frigg'n fast ... and it finally fell into place. In short, the M3 is geared much higher than my car -- about 3.7:1 vs 3.07:1 for the C43 -- and can pull much longer in a gear than my car (33% longer to 8000 redline than to a 6000 redline). All resulting in much higher torque multiplication in the drivetrain, resulting in a much higher force at the tire's contact patch, which in turn results in much higher acceleration

Click here then search for or scroll down to 'mbc43amg' (http://www.mercedesshop.com/shopforum/showthread.php3?s=&threadid=74101) (mbc43amg is me on that board)

A discussion about how torque and gearing relate -- a favorite of mine. (http://www.amg-owners-club.org/board/en/wbb2/thread.php?threadid=2454&sid=&hilight=&hilightuser=850)

Hope you enjoy.

speedybenz
10-16-2003, 10:09 PM
I copied this from another post I wrote awhile ago. It says the same thing as 98c43amg has said, but in just a little different fashion.


98 Benzo,

I thought I would chime in on the "What gets you up to speed" question.

Although torque is nice, its really Hp that moves you. Torque is the measure of force the engine produces, but Hp is the product of the torque and rpm. Think of rpm as the number of times that the torque is applied to the crankshaft.

So an engine makes 200 ft-lbs of torque and then can produce it 12,000 times a minute and you make about 454Hp and and your car will rip. The car will have a different feel to the speed it produces but it will get up to speed quickly.

This is why you see normally asperated engines turning lots of rpm to make big power. Even Nascar engines are turning close to 10,000 rpm these days. It is all about making as much torque as possible and then applying it to the crank as many times as possible per minute

Jeff

C280Sportster
10-17-2003, 07:13 AM
I'm reading now and starting to put the pieces together.

Maybe that's why the C280 is a tiny bit quicker than the C230 Kompressor (280 has a higher redline), and the Kompressor has a lower rear axle gear (3.27:1). Both cars make two shifts getting to 60, but the C230k would have to shift sooner, there by falling behind…but people say in the real world the C230K is faster, so I don’t know.

The C43 vs the new M3 is interesting. I wonder how much speed is lost in the auto tranny, because with 302 HP and 302 lb of torque, it should be right behind the M3 (M3 claims a 0-60 time of 4.8 secs). From reading, I can see how the M3 has a gearing advantage, thanks to it’s engine design (high RPM), the M3 only has one shift from 0-60, so the M3 passes 60 in second gear. By my guesswork, one shift = about .5 seconds lost, auto or manual (SMG also?). So BMW was kind of smart (it is also clever marketing, it would definitely help sales having a sub 5 second 0-60 time, 4.8 as opposed to 5.3 secs) to do this, especially if the high rpms help on the track.


Two questions:

1) Since you guys are increasing your HP/Torque, would it ever make since to raise your rear axle gear? I know 0-60 doesn't mean much in today’s world, but maybe it would also help your 1/4 mile, by eliminating one shift? It might also increase traction.

2) Why does MB design engines the way they do, seems like the C43 could have been made to beat even the new M3 with slight changes. There has to be a give and take to every design, where does the M3 fail (high speed, engine won’t last, roll on, ¼ mile, engine isn’t smooth) and what is MB shooting for with their eingine designs?


My take is: Mercedes seems to take a conservative approach in engine design, never max-ing out the power, building engines that will last 200,000 miles, and keeping the RPMs low and providing smooth power throughout the power band.

98c43amg
10-17-2003, 11:47 AM
Originally posted by C280Sportster
1) Since you guys are increasing your HP/Torque, would it ever make since to raise your rear axle gear? I know 0-60 doesn't mean much in today’s world, but maybe it would also help your 1/4 mile, by eliminating one shift? It might also increase traction.


When you say "raise your rear axel gear", do you mean a higher ratio number, as 4.44:1 or lower ratio, as 2.45:1. To eliminate a shift, it would be the latter. (But I'm just checking.)

Assuming the latter, that's really only appropriate if the car's making a good deal over 400hp.

If you hadn't yet, read my third link above, "A discussion about how torque and gearing relate -- a favorite of mine". As far as I know from my research, the C43's not producing enough torque yet to see advantages by raising the shift point. Much more gains by lowering it.

I've run my spreadsheet to calculate acceleration with 3.27:1, 3.45:1, 3.75:1 and with even 4.44:1 gears in my car. The last one has the C43 crossing the 1/4 mile mark @ about the power peak in 4th gear, as god intended ;), instead of in third as auto tranni cars always seem to be geared to do ... about a second and a half quicker than stock. Though I doubt the car will hook-up with its open rear, as the force figures at the tires in 1st gear were well over the weight of the entire car. I'll have to try it with say, 2.55:1 and 2.0:1 gears too. I'll get you the results but I'm sure they'll be slower to the 1/4 mile, not faster.

To get the most out of a 300hp car (or even 350hp or 400hp car), it's better to stick with a higher ratio, and keep the force through the rpm range as high as possible, without that force being greater than the fraction of the weight of the car you're able to load on the rear drive tires, else you'll light up the tires; read PhorS for the physics behind weight transfer. For a street car with street tires, the amount of traction the tires can provide are in a large part governed by the car's weight , with of course the contact patch's size and the rubber formula playing a role. Thus a higher ratio is needed if your car isn't producing well over 400, 500, 600hp to get the force you're putting down to the tire's contact patch be as close to the maximum as they can handle. Once you're getting well above 400hp, you need to do as you're mentioning, and lower the ratio so as not to overwhelm the tires, and spread that nice high, wide, torque curve over a wide mph range.

If you haven't read that link above, as a decent compromise, I was interested in increasing the gear ratio from what it is now, from 3.07:1 to about 3.45:1 on my C43. The compromise of it is if you can't increase the car's redline by at least 500 to 1000rpm, you're actually accelerating slower for the next few mph right after a shift (at redline) than you had before, since you had to upshift sooner into a higher gear that has lower force multiplication from the drivetrain; so you're giving back a little bit of those gains for a few mph until you reach the mph value where the previous/stock tranni would have upshifted too; then you're accelerating quicker again with the higher ratio; until the next upshift. But that compromise is not enough to negate the gains overall.

I'll provide some statistics I calculated from my acceleration simulation spreadsheet with lower ratio gearing too.

98c43amg
10-17-2003, 12:00 PM
Originally posted by C280Sportster

2) Why does MB design engines the way they do, seems like the C43 could have been made to beat even the new M3 with slight changes. There has to be a give and take to every design, where does the M3 fail (high speed, engine won’t last, roll on, ¼ mile, engine isn’t smooth) and what is MB shooting for with their eingine designs?


My take is: Mercedes seems to take a conservative approach in engine design, never max-ing out the power, building engines that will last 200,000 miles, and keeping the RPMs low and providing smooth power throughout the power band.

The biggest factor in this comparison is the redline of the engines. If a C43 had a limited slip 3.65:1 rear with a redline above 7000rpm, it would be right at the level of the new M3 if not above it -- even with the auto tranni.

Look at the new Audi S4. Same torque as the C43 @ about 300. However the Audi's power is 340 ... why? Because it has a 7000rpm redline. ...and just like I've been thinking is optimal for the C43 for the last few years, it has something like 3.45:1 rear diff gearing. The end result? Its complete package is said to be the closest competition the M3 has in a similarly sized car. Yes, the C43 could have been there 5 years sooner!

I agree with your take on it.

C280Sportster
10-17-2003, 01:09 PM
Originally posted by 98c43amg
The biggest factor in this comparison is the redline of the engines. If a C43 had a limited slip 3.65:1 rear with a redline above 7000rpm, it would be right at the level of the new M3 if not above it -- even with the auto tranni.

Look at the new Audi S4. Same torque as the C43 @ about 300. However the Audi's power is 340 ... why? Because it has a 7000rpm redline. ...and just like I've been thinking is optimal for the C43 for the last few years, it has something like 3.45:1 rear diff gearing. The end result? Its complete package is said to be the closest competition the M3 has in a similarly sized car. Yes, the C43 could have been there 5 years sooner!

I agree with your take on it.

I did mess up, but you caught it. I meant lower the rear gear, but as you said you need more 400 HP to take advantage. I'm starting to see what you mean about the M3 design...so what would be best for the your C43 (since you can't increase the redline), would be to have a "higher" rear axle ratio and move through the gears faster and stay in the powerband ? So, a basic question, is it better to have a higher RPM limit, but I guess it depends on how much torque is being produced at that high RPM.

SO:

"The higher the redline is, the longer you can run in a lower gear, giving you the advantage of torque multiplication in the lower gears while travelling to/at a higher linear velocity; that higher torque multiplication of a lower gear, longer, then directly translates to more linear force at the wheel's contact patch (through the driveshaft, differential, axles, to the wheels/tires)."

So, the M3 seems to have found a sweet spot (except for all the engine problems) and other car makers don't want to go there (no market maybe).

I did forget the M3 has 6 gears, now I see why that may help, you can raise the rear axle ratio and still have decent gas mileage at highway speeds using the 6th gear.

I wonder if MB's 7 speed tranny will help acceleration, we can assume it will help MPG. I hope it shifts fast.


Two more question:

1) How much power are you trying to get from your engine and how will it help ?

2) Would something like the 7 speed tranny help a C43 ?

I think you could easily get 30 more HP, would that make a difference in your 1/4 mile time ?

speedybenz
10-17-2003, 02:13 PM
Higher Rpm only helps if the engine is continuing to make enough torque so that Hp is also greater. The torque curve can fall off at higher revs and you can still make more peak Hp, torque just can't fall too quickly.

In the case of the C43, it does continue to make more power all the way to redline, so it would benefit from a higher rpm limit.

Yes the higher numerically you gear the differential the faster the acceleration.

Auto tranny's have one more varible and that is the stall speed of the torque convertor. If you set the convertor to stall at a higher speed the tranny can spin up right through a soft spot in the power curve, right up to a place where power is good. That way you waste little time between shifts.

The C43 and C280 can spin up to 7000 rpm without prob's related to piston speed, they just need a change in the basic chip programming to allow for this change.

Jeff

98c43amg
10-17-2003, 04:59 PM
Originally posted by C280Sportster

I wonder if MB's 7 speed tranny will help acceleration, we can assume it will help MPG. I hope it shifts fast.
Two more question:
1) How much power are you trying to get from your engine and how will it help ?
2) Would something like the 7 speed tranny help a C43 ?
I think you could easily get 30 more HP, would that make a difference in your 1/4 mile time ?

I heard the 7-speed tranni nets something like a reduction of 0.3 seconds 0-60. I imagine it would help any car. :)

Me, I'm not doing anything yet. Speedybenz is the master there no doubt.

If I do anything, I'd like to do a supercharger coupled with a freer flowing exhaust. HPS is closer to what I want to spend; Kleemann is quiter an offers more bang but for much more bucks. Still too rich for me. I'm trying to talk Kenne Bell into producing a kit for my car. :p They use a twin screw design for only about $4K.

Plus, I have a major love/hate relationship with my car [hate part coming from the tranni]. Car's strong and I'm hard on cars. It would be smart for me to keep it. But I just hate the tranni. So I don't know if I'm going to stay with it ... so don't know if I want to put more money into it than the Command & phone I just did.

speedybenz
10-17-2003, 08:09 PM
98c43amg,

Can you please post your spread sheets on the gear ratio's and such. I would really like to look at the data.

From what you know can the ECU chip be changed to allow the redline be moved up to 7000rpm.

Jeff

98c43amg
10-17-2003, 10:06 PM
I've been wondering where? I wanted to a few times, but I don't have any web space.

It's also pretty out of hand now. I've been inserting column after column and it's become pretty unruly. I'll want to re-do it before publishing and clean it up a bit. Also, I was thinking of re-doing it at 1 or 10 rpm increments (it's at 100 rpm increments now) and adding time delays between shifts. (@ 1 rpm it might be too long and unruly the other way, length.)

After I do that, you know anywere I can register for free webspace, free of download limitations? (w/o getting spammed to death at the e-mail address I use to get it :eek: )

EDIT: I just noticed I read your question incorrectly. I thought you were making a statement of knowing the ECU can be modified to provide a 7K redline.... Now that I read it correctly, no, actually I don't know about the electronics, or also, if it would be damaging to the engine. I'd love to know if the crank bearings and heads (primarily valve springs?) can handle continuous runs to 7K myself.

98c43amg
10-19-2003, 07:40 PM
Originally posted by 98c43amg
I'll provide some statistics I calculated from my acceleration simulation spreadsheet with lower ratio gearing too.

As promised, though I doubt it's necessary anymore...

Stock car 0-60 is about 6.1 seconds tested by Car&Driver, w/ 3.07:1 rear diff.

My spreadsheet results are 2.5:1 gears would take 6.6 sec 0-60mph, 2.25:1 gears would take 6.8 seconds 0-60mph. (assuming 6250rpm redline shifts)

C280Sportster
10-19-2003, 09:05 PM
Originally posted by 98c43amg
As promised, though I doubt it's necessary anymore...

Stock car 0-60 is about 6.1 seconds tested by Car&Driver, w/ 3.07:1 rear diff.

My spreadsheet results are 2.5:1 gears would take 6.6 sec 0-60mph, 2.25:1 gears would take 6.8 seconds 0-60mph. (assuming 6250rpm redline shifts)

I think the C43 can get to 60 faster than that. Of course those stock wheels weigh 50+ pounds I think.

The Evo underdrive pullies give 13 hp in first gear to the 320 motor, I wonder what it would do for your engine (and I think it's 13 hp at the wheels).

The UD pullies will be my first mod, when I get around to it.

What does your spreedsheet say for 3.27:1 and up ?

I think speedy was saying that MB lowers the redline to protect the engine and that maybe with a chip we can get into the 7000 rpm.

98c43amg
10-22-2003, 08:06 PM
Originally posted by C280Sportster

What does your spreedsheet say for 3.27:1 and up ?


3.27:1, Not much. The 3.27:1 gear is only about 6% gearing increase (thus force increase @ the tire's contact patch) than the stock C43 gearing. About 0.2 second reduction in 0-60mph. Doesn't change performance all that much; really not worth it IMHO given the cost.

speedybenz
10-22-2003, 08:29 PM
Just for Info. Toyo makes a TS-1 tire that is a 245/35/17" that is only 23.5" or so in diameter. I know you can run the 245 in front on a W202 so running this tire all around would change your gearing some 6% and should make a difference in 0-60mph times for just the price of tires.

But because of the small diameter I think you need to run it at all four corners to keep the ASP or ESP working.

Jeff

C280Sportster
10-22-2003, 09:13 PM
Originally posted by speedybenz
Just for Info. Toyo makes a TS-1 tire that is a 245/35/17" that is only 23.5" or so in diameter. I know you can run the 245 in front on a W202 so running this tire all around would change your gearing some 6% and should make a difference in 0-60mph times for just the price of tires.

But because of the small diameter I think you need to run it at all four corners to keep the ASP or ESP working.

Jeff

Not to go off topic, but we are talking about engine power here.

I'm pricing some DENSO Iridium Spark Plugs and they are coming in at over $12 each. If they produce 3 HP I think they are worth it. My plugs need changing anyway. What do you guys think. They would probably help an AMG even more.

Check out this link:

http://www.densoiridium.com/tunerstales.php

and click on the 1997 VW (well, click on all of them).

They say 6 HP for the VW...I don't know if its true, unless the old plugs were, well, just old.

I'd spend $120+ for 3 hp (at the wheels ?). That's cheap in Mercedes land.

I wouldn't mind smaller tires, but that's a long way off, I have plenty of tread left.

speedybenz
10-22-2003, 10:05 PM
The Denso's do seem to be a very good plug for our MB's.

Back on the raise the rpm limit issue I did some checking of the bore and stroke for the BMW M3 and the C43. The M3 has a stroke of 3.58" while the C43 has a stroke of 3.307".

It just makes my arguement even stronger that the rpm limit on the c43 could easily climb up to 7000 rpm provided that the valve train can handle the extra rpm without valve float.

Jeff

CKlasse
10-23-2003, 07:12 AM
Wanna do group buy on Denso? I can always get them at my distributor.

BTW.. do you have inline or V6, C280?

C280Sportster
10-24-2003, 05:43 PM
Originally posted by CKlasse
Wanna do group buy on Denso? I can always get them at my distributor.

BTW.. do you have inline or V6, C280?

I have the V6, so I need 12 plugs (ouch). How much can we save with a group buy ?

CKlasse
10-24-2003, 06:06 PM
I ll check on this on Monday :)

speedybenz
10-27-2003, 08:04 PM
The site below has the best price on Denso plugs I have found. $10.99 ea.

http://www.ltbmotorsport.com/densoik165303.html

Expensive but worth it.

Jeff

WeatherMan
10-29-2003, 02:50 PM
I'm up for the group buy! I'm a little worried about the difficulty in changing the plugs- haven't tried to get to all 16 yet...