Throttle response

Why do the 996s have such crappy throttle response? My friends E46 M3 clearly revs quicker than my car but the M3 has about a 0.6 inch longer stroke.

I also noticed that M3's are freer reving than my 996 in the lower end of the rev range. I don't know why, just sharing your observation. That's one advantage the M3 has over our cars, there not many others. Overall, when I add up all the plus's & minus's, the 996 is a superior car in my opnion. When I want to pass an M3, or any other car for that matter, the trick for me is to anticipate the pass by making sure I keep my revs up...... it works every time!

I think you a little off base here. Unless you are reving the cars in neutral and comparing time to a rev range, the difference you will notice is principally gearing, not throttle response. The length of the throttle throw has nothing to do with an engine's throttle response.

Revving both cars in neutral, the M3 is a bit peppier IMHO. I didn't time the differences, it just "felt" that way. I guess I didn't catch Tippy's comment about a longer stroke and I'm not totally sure what he meant by that..... travel distance of the throttle???

I used to own an e46 M3 and it definitely felt like the throttle was quicker (especially in the sport mode). Overall, the 996 however feels much more solid (especially in corner) and will be faster if you know how do drive it. Additional bonus, my C4S in the snow, no comparison whatsoever!

LiveNupe, where you at the poc day last sunday in MP? I have a great video of me following you if that was you. That was fun trying to keep up with you.

Stroke is for me referring to the distance the piston travels in the cylinder from the bottom of the stroke to the top. Reference being that the longer the stroke the longer the throttle response. I am not sure about that one though?

How am I off base, I am clearly talking about free revving. I am not speaking engine under load in first gear, obviously the M3 will win because it has way, way more gearing than a 996. My point is that the stroke of an M3 is almost 0.6 inches more than a 996, this should ultimately give the 996 an easier advantage to rev. I guess it boils down to runner length, the M3s throttle bodies are directly mounted to the heads whereas the 996 has a long intake tract. Even so, a 302 V8 Mustang enigne has the same stroke as 996 and revs a lot quicker. It shouldnt since the V8 has more rotating mass but it does, not to mention the V8 has a very, very long intake tract.

Thanks, now I know what you meant by stroke. I think speed to a given RPM has far more to do with rotating mass than anything else. Less rotating mass, the faster the engine will accelerate. We can build one that will go very fast, and last for a week. I am not saying a M3 engine does not have quicker throttle response than a 996 engine. I don't know. The M3 engine is extremely impressive, but I doubt your -crappy- assessment is correct when compared with other engines. Having owned several V8 Stangs (my beater is a 4.6l Cobra), I am extremely confident that those engines do not rev faster.

my car revs fast and stays wound up even at throttle lift.

try changing the pulley or the flywheel. the car should "rev" much faster......

I sold my E46 M3 to get my 40th Ann. 996, and did not notice much of a softening of throttle response. However, the M3 has 6 individual throttle bodies which (in addition to looking really cool) may account for the effect you describe.

surprised nobody mentioned e-gas and improved throttle response through software updating.

With an electronic throttle you do not have direct control over the throttle. You can press on the throttle till your leg breaks and if the computer doesn't want more power you're just SOL. The actual response is governed by a map in the computer who's response in turn is governed by a bunch of variables. So different maps re:cars, will yield different response, everything else being the same. I'm not thrilled with these things, but is part of the price you pay to have a clean burning somewhat efficient engine.

yup... the 99 has throttle by cable and that is as direct as you get .. GIAC's upgrade includes better throttle response...

Does the variable cam timing play a role in this?

I believe the vari cam timing is a function of the RPM not the other way around.

right. for me, can't comment on flywheels or e-gas, but i did notice same feeling the first time i drove a 911 (2000MY). the throttle response was strangely mechanical, and when combined with the terrible std shifter, i was pretty shocked by how unsmooth the car felt- compared to my bmw's. the slick 6-speed coupled with the throttle response of the inline 6 in my 330 ZHP feels like my drivetrain is encased in warm butter-- super, silky smooth all the way to the redline. even with my new SSK which vastly improved everything, i can't say my 911 drivetrain is smooth. although, of course, it's way more fun.

throttle response on my e46 m3 was definitely more instant than my c4s those six computer controlled throttle bodies is insanely sweet and the inline 6 is butter smooth

put an evo cai, exhaust, and a flash... then a LWF. Now were talking, problem solved

Throttle response is great on my '99 Cab, and on my wfe's '99 Boxster as well. It feels like the throttle cable is hooked directly to the back tires like it should. For those that don't know, throttle response means INSTANTANEOUS and IMMEDIATE response from the motor as the throttle or gas pedal is pressed. No momentary lag or millisecond waiting for things to happen.

LWF is not for those people who were changing their clutch pedal assist springs last week, though, in an attempt to not stall out in 1st gear. :-) Bill

I noticed that as well, the M3 revs quicker than our cars. But the M3 also has a lame exhaust note to go with the revs! Stock vs stock, the P's exhaust puts the M3 to shame. Anyone tried revving the rotary engine in a RX7 or Rx8? Those things rev even quicker, like a 2-stroke motorcycle!

Probably the fact that there's hardly any intake valve lift at low RPMs (for economy) and the car has a 900 lb. flywheel.

+1 A light weight flywheel will cure that.

Don't forget there is real throttle response and fake throttle response. It's easy to change the mapping between the pedal and the throttle body(s) to make the car feel like it's reving faster because for a given amout of pedal input you get more input at the throttle. That was a favorite trick on older cars. Just change the throttle cable cam on the throttle body or carb and the owner thinks the car is a rocket ship. "I barely touch the gas and the car revs like crazy." Porsche does the same thing with the "sports tuning" on the new cars. Jim

but Jim, there is no gimmick to the M3's throttle response mechanics. again it's got six individual throttle bodies controlled by their M ecu. it's awesome. now the sport mode is a bit gimmicky because it makes the car almost too touchy.

So there's no gimmick unless it's in sport mode? Older BMs without electronic throttle had complicated linkages on the throttle body to alter the shape of the opening curves. That is a gimmick and I'd bet dollars to donuts there's a huge amount of code in their modern ECUs to map those throttles in ways we couldn't begin to guess here.

no there isn't because the real world result is it works GREAT in non-sport mode. throttle response is razor sharp. in sport mode, it's difficult to heel-toe because the throttle mapping is so aggressive a little input results in too much revs to the point where it's untenable. sport mode doesn't accomplish anything other than making a lot of owners who don't know or care to know think it's putting down more power and making them faster. i agree on the ecu stuff and how it's out of reach of many to understand what's really going down... kinda like suspension tuning which really is black magic.

FWIW, I've always found the throttle response of any Motronic 911 to be like a lawn mower compared to the old Weber or MFI versions. I don't remember what the CIS cars were like.

Sport mode was never intended on the E46 to produce more power but sharpen (raise) response times (The newer M's; see M5 do make more power with this). If you have driven any of the non M E46 cars, the electronic throttle was absolutely numb. After applying large amounts of throttle, it would take a noticeable amount of time before the DME recognized that you wanted to increase your speed. It felt almost like turbo lag. With the M, the sport mode was fantastic on high performance situations as it let you modulate without using as much input (really made it crisp where the normal setting was like the standard cable E36 cars). Something that many track junkies and Autocrossers liked. It really is personal preference as the 02 that I co-drove a few years back (in an autocross series), I preferred the Sport mode as I didn't have to be as dramatic with throttle inputs to move the car and could make the car rotate with my right foot with less movement, as the owner of the car didn't like it on the same course. Pete

LJ, I hope you're merely reiterating/clarifying a point I've made about sport mode that it doesn't add more power, but simply remaps the throttle input to how the engine reacts (by about 50%). I think it's a subjective thing as to whether you like sport mode on or off on the streets or at your local auto-x (I am agreeing with you here). For the few friends of mine who own the E46 M3 and track it, they don't like sport mode at all for any purpose.

I wasn't trying reiterate just your point but to expand a bit on it. I also might have hit the wrong poster's quote as to alluding that sport mode for the M3 was a gimmick. It's not at all. It makes the car much more entertaining and adds to the character of the car. Sport mode forces you to be much smoother which makes you a better driver in the long run (IMHO). That's interesting that your friends didn't like it. I loved it the second I tried it and compared it to normal setting. I found it easier to modulate throttle in an oversteer as the degrees for throttle applied where available without having to move the pedal (in what I perceive as too much distance). Perhaps it's my Jeep back ground with the insanely touchy gas pedal on my old wrangler and I'm used to that. Pete

Man I posted this a long time ago. Anyways, my point was, the 6 throttle bodies are on the side of the head (M3) so naturally the throttle response should be quicker but the M has a 0.6" longer stroke. Shorter stroke motors naturally want to rev quicker than longer stroke motors, that is all. So, it is not the stroke, it has to be something with the E-gas or the fuel/ignition mapping.

if everyone liked the same thing it wouldn't be nearly as fun (i am reiterating and expanding on your point)