How does the M3 get 330hp from 3.2 liters?

[nsxtasy]

Originally posted by BoneZ:
Ive seen this term pop up a few times, whats the "i" stand for? I understand the RSX has this iVTEC, but what exactly is this new iVTEC, and whats so different about it compared to traditional VTEC which we all know and love?

From Acura's website:

i-VTEC™ Technology

Acura's Variable Valve Timing and Lift Electronic Control (VTEC™) has set unmatched standards for extracting ample low-rpm torque and high-rpm power from the same engine. But a new technology that makes its debut in the RSX and RSX Type S takes VTEC a step further. It's called i-VTEC (the "i" stands for intelligent), and it helps both engines respond quickly while it improves fuel economy and reduces exhaust emissions.

In addition to controlling valve lift, timing and duration the way other VTEC systems do, i-VTEC uses Variable Timing Control (VTC). By regulating oil pressure, VTC adjusts the phase of the intake camshaft, advancing or retarding intake cam timing (relative to exhaust timing) in order to keep power output smooth across the rpm spectrum on both RSX engines.

In the 160-hp RSX, the VTEC modulation of i-VTEC works on the intake valves exclusively, using a 2-rocker arm design. At lower rpm, the second intake valve opens only partially, creating a desirable swirl effect in the combustion chamber. At higher rpm, both intake valves open fully, for quicker, easier breathing and full power output. In the 200-hp RSX Type S, an exclusive 3-rocker-arm design operates on both the intake and exhaust valves, developing incredible low-end torque and high-end power. At lower rpm all valves open to a lower profile that changes to a higher profile, with a longer duration, at higher rpm. In both engines, i-VTEC is designed to get not only the best results at a given rpm level, but the best performance possible from each individual engine revolution.

 

[Fabian Gramer]

E46 M3 engines have been blowing up even with the computer controlled SMG II 6 speed transmission, which in theory shouldn't allow you to mechanical overrev by downshifting into the inappropriate gear for given vehicle speed.

Here are various owners accounts
http://members.roadfly.com/jason/m3engines.htm

Having owned several M3 (E30, E36) in the past, it's really kind of dissapointing. That was the most appealing part of the E46 M3- the engine. It was nice to see that given a few years of technology advancements, you could produce exotic car type hp/l in a non-exotic priced/type car.

Remember that the E46 M3 was delayed to engine problems before finally being released to US market.

Perhaps they should consider the forced induction route like Merc V6 AMG versions have or baby M5 V8's. They don't have the high-revving fun, but they don't necessarily blow up either!

-Fabian

[This message has been edited by Fabian Gramer (edited 06 June 2002).]

 

[NetViper]

It sounds like these high-output/L engines are having trouble.

Is the S2000 also having this trouble? Anyone heard of S2k engines blowing up?

I think I would prefer to stay under 100hp/L if it means my car wont explode

 

[nsxtasy]

The Integra Type R is not getting a deluge of engine explosion reports, yet gets over 100 hp per liter.

 

[inline6]

Jimbo,
I dont have the book Advanced Engine Technology by Heinz Heisler here (I think that's where I read it) but in his Vehicle And Engine Technology book, he has this to say:
about Inline-6 engine: "This arrangement has excellent dynamic balance and evenness of torque, and is preferred for engines larger than 2.5 liters if length is not a prime consideration."

about V-6 engine: "The dynamic balance is relatively good with this layout, which provides a short compact engine unit compared with the inline six."

By length, he means engine length where an inline-6 can be 30% longer than a same capacity V6 which is why V6s are used in front-wheel drive where the engine runs between the wheels (same with NSX). Kind of explains why there's a 3.0 V6 in Camrys and ES300 and there's a 3.0 inline-6 in Supras and GS300.

 

[Jimbo]

inline,

I can understand why an inline 6 might be better balanced and provide more even power (i.e. no need for balance shafts, etc)...

But I don't think there's a inherent reason why an inline 6 would provide more torque over a V-6.

-Jim

------------------
1992 NSX Red/Blk 5 spd #0330
1991 NSX Blk/Blk Auto #3070 (Sold)
1974 Vette 454 4 spd Wht/Blk
Looking for 76-79 Honda Accords

 

[MAJOR STONER]

The BMW makes a lot more grunt at only 1500 rpm, and the variable valve timing is better than Honda's.

"The M workshop engineers gave more power to the M3 mostly by retaining the oversquare design and increasing the rpm. Similar to how a Formula 1 race car's V-10 can produce gobs of horsepower at 18,000 rpm with pistons covering about 82 ft. per second, the inline-6 in the BMW, at its 8000-rpm redline, has a piston speed of more than 79 ft. per second. The result is a 6.9-percent increase in horsepower and 4.3-percent improvement in torque over the previous power unit, delivering 343 bhp (DIN) at 7900 rpm and 269 lb.-ft. of torque at 4900 rpm. The M3's specific output of 106 bhp per liter is one of the highest naturally aspirated production 6-cylinders in the world.

Using the previous-generation M3 engine block as the starting point, the stroke was lengthened from 89.6 to 91.0 mm, and the bore increased from 84.6 to 87.0 mm. To cope with higher engine speeds and the 11.5:1 compression ratio, lighter graphite-coated cast-aluminum pistons with forged cracked-steel connecting rods are employed. Cooling for the powerplant comes from oil-injection jets for the pistons and a single-piece 4-valve-per-cylinder head with integrated cross-flow coolant passages for more even distribution of heat. The M3 also uses a quasi-dry-sump system to ensure that the engine is well lubricated even when the car is subjected to high lateral loads or straight-line acceleration.

BMW's MSS 54 management system, capable of performing 25 million calculations per second, controls the VANOS variable intake and exhaust camshafts to meet the high-revving M3 engine's demand for oxygen and its need to deplete spent air. It is also in charge of relaying throttle input signals to six electronically controlled butterflies directing air into the combustion chambers. One welcome feature is a switch on the instrument panel for sport mode that tells the MSS 54 to change to a more aggressive mapping of gas-pedal travel and throttle butterfly opening, allowing for quicker response as already seen on the Z8."

 

[nsxtasy]

Originally posted by MAJOR STONER:
the variable valve timing is better than Honda's.

It sounds very similar. Why do you say it's better?

 

[NetViper]

I thought BMW's new system was fairly similar to i-VTEC... but I could be wrong..

 

[G_Man_Max]

Well guys we all know the age of the NSX is getting on a bit now, 11 years old + 3 yr design cycle =14yrs, so compared to the lovely BeE-emM'S we are not doing so bad.
However the advances in todays fuel mapping technology and with improved headers, intake and good free flowing exhaust we can almost reach the magical ~300hp without the benefits of forced induction.
What I wondered is why there dont seem to be throttle body kits easily available for the X, although over here in europe its one of the best ways to release extra power from the engine ( in conjuntion with fully mapped injection and ignition systems ).
I know its possible as I've seen this car (JDM) with it, but does anyone know where its available from ?

[This message has been edited by G_Man_Max (edited 07 June 2002).]

 

[nsxtasy]

Maybe Honda just did a really good job of designing it in the first place.

BTW, comparisons like

Originally posted by G_Man_Max:
Well guys we all know the age of the NSX is getting on a bit now, 11 years old + 3 yr design cycle =14yrs

aren't really valid. If you're comparing it to a new BMW, that car had a three-year (or longer) design cycle as well, so the NSX was not designed 14 years before the BMW the way that statement would seem to imply.