I say you just use the weights of a 6MT G37 and a 6MT 335i, per manufacture claims; as long as its the same tranny it should be fair. (Or, you can use the weight figures of a head-to-head comparison review as they might have tried to weigh them in with similar fluids).

If you start using weighed in figures by other people, there's more room for error since people weigh their cars with varied fluid levels and other possible variables.

 

The only VQ I would ever consider adding boost to would be the VQ30DE found in the 95-01 Maxima. Due to the over-square nature of this motor, it has velvety smoothness and behaves much like an inline 6. The motor can happily rev to 7500rpms with the assistance of stiffer valve springs and an upgraded oil pump and the over-square nature makes it very strong plus it has to rev less to make power. There are many single turbo 400whp+ Maximas out there on 100K+ VQ30s and most are on stock fuel systems and there are nitrous/turbo Maximas hitting 500whp+. These are bonestock motors too. It can handle it quite nicely. I'd love to have a VQ30DET in my G. Better yet, why not just get the real VQ30DET they sold over in Japan

The VQ35 has a longer stroke which puts more stress on the rods. The VQ37 has an even longer stroke. These long rods used in the VQ35/37 are light because the motor needs the revability to obtain the high HP numbers. Their lightweight nature doesn't make them ideal for the stresses of boost. The BWM I6TT uses a really long stroke, but compare a rod from that motor to the VQ35/VQ37 and the difference is obvious.

Also, lets stop focusing on WHP numbers. The shape of the powerband dictates the real acceleration potential. I'd much rather have a 500whp/500wtq motor over a 600whp/400wtq motor any day and chances are the 500/500 motor would be faster because it would have a wider and more useable powerband.

I'd never want 600whp VQ37 or a 600whp 335i. I would consider neither car "reliable" in even the loosest definition. I'd much rather have a 400whp 335i which I think would be pretty dang reliable, especially since motor an underrated 300hp (more like 340hp).

 

BMW 335i sedan
~3350lbs
CD 0.30
Swept area 640 sq.in.

G37 sedan
~3700lbs
CD 0.29
Swept area ?

 

335 sedan is over 3600lb. Where did u get that figure. It is not a light car. 328s are little over 3400lb.

 

This is going to go a bit out of the scope of the original post, but I would say that preference of the 500/500 vs 600/400 would depend on the gearing.

Lets say that they have identical gearing, and ideal powerbands (i.e. perfectly flat torque). Naturally, the 600whp motor has to rev higher, so the gearing will be taller if the ratios are the same.

Now, lets compensate the ratios so that the mph result is identical for both motors. The end result, when you factor in gearing, is that at the bottom half of the powerband, the 500/500 puts more thrust on the ground, but the 600/400 motor does more at the upper half, but the 600whp motor is still faster, because more work is being done.

The 500/500 motor may be faster off the line, but as soon as you get about halfway up the powerband, the 600/400 motor is simply creating more power. Everyone seems to forget that in a drag race, the only portion of the "area under the curve" that is used is the upper half (or less) Yes, for daily driving, having more torque makes the engine far more lively. A prime example is my s2000 vs my g35. In my G, I rarely went over 2500 RPM or so. In the s2000, I'm never under 2500. The G is creating far more torque, but horsepower is ultimately what makes the car move, and 2500rpm in the G creates roughly the same amount of power as the s2000 at 3500 rpm, conveniently the RPM's that I roughly shift at during daily driving.

The best way to Illustrate this, is to use a CVT tranny. If we put that CVT tranny on the 500/500 motor, and the 600/400 motor, which do you think would be faster? The 500/500 will be putting out 500hp the whole time, and the 600/400 is putting out 600hp the whole time.



Also, in regards to stroke, my understanding of physics would dictate that piston speed is the biggest determining factor in the strength (and thus weight) of the connecting rod. The G's piston speeds are near that of a F1 car, which is generally considered to be close to the mechanical limits of the alloys we have available today. The connecting rod must be strong enough to handle opposing acceleration of 250 times per second, yet be light enough that it doesn't exert too much lateral force on the piston (and stressing the cylinder wall). Personally, I feel that Nissan has done it right by increasing redline and increasing stroke. Higher revving engines tend to last longer than bigger displacement engines, simply because they have to be better engineered to cope with the additional stress of the high rpm.

As such, the additional strength mandated by high RPM often lends itself to being FI friendly. The HR/VHR is taking boost very well, as are other high RPM motors in production. (Japanese I4 motorcycles and F20C comes to mind).

 

per BMWUSA.com

335 sedan: 3605lbs
335 coupe: 3582lbs
0.30 Cd

per Infiniti.com

G35 Sedan: 3,590 (I can't get a weight with the sport on a 7AT; I will add 50 lbs as a rough estimate for the brakes).
0.29 Cd

Remember that once weight is factored, one set of power curves will simply shift up or down, and then we can integrate for "are under the curve" the bounds of the integral are the vehicle speed of the given 'race'.


FWIW, the G's governer is higher if you want to go that fast =p

 

Can we roughly compare how the HR37 na is built vs how the VHR37TT is built for rough comparison? I know the GT-R motor puts out more hp but it would be interesting to see how each are built.

Same with the VG30DE and VG30DETT, VQ30 and VQ30-T. Or was it the VQ28-T?

 

For sure, it is cheaper to get 400WHp out of the 335 than it is to get the same power out of the G - but it can still be broken depending on how it is driven.

 

It was a typo. I meant to type 3550lbs.

 

edited


Great work with the graphs. Easy to read and understand. Cudos.

 

lol i would take the 335 hands down(if i had the money to buy and maintain it)