Early shifting would help if the power dropoff is severe enough (like on the VQ35DE). My belief is that there is a dropoff, but not enough to warrant early shifting.

Basically, the break-even point, is you should shift when you're making the same whp in the next gear as the one you're shifting from.

If it's like a s2k or 2nd gen G, where the power keep climbing, then a redline shift is best. (with an increased redline through reflash, short shifting may be better in the upper gears)

 

I completely disagree. Just because a car can carry more HP at a higher rpm doesn't mean it's a faster car. You've got to look at power under curve because that's what dictates the acceleration. The 335 simply has a much fatter powerband and more power under the curve, especially in the range that you spend most of your time accelerating (4000-6500rpms). The HR continues to gain in a linear fashion whereas the 335 delivers a huge wallop of power from 2000rpm all the way to 6000rpms. No only in the car far easier to launch, it's much harder to accelerate from 0-30mph which is by far the most important acceleration point in a drag race.

If I had a choice between a 500hp/450tq car and one with 600hp/350tq, I'm going to take the 500hp car every time because it has a far better powerband to work with and will most likely be the quicker car in the 1/4 mile.

 

You are completely right by implying its the average horse power throughout the RPM's at WOT that will determine which car is faster (assuming the same weight and gearing). (Tony from Motordyne explained it to me a while back in a perfect manner).

But in this example you just stated, gearing will have a huge impact in determining which car is faster overall. Yes, a 500hp/450tq car will have more usable power throughout the whole powerband. But that doesn't mean its going to be faster than a 600hp/350tq.

 

the 335's fatter powerband is nice for daily driving. When drag racing, the only area under the curve that matters is the area being used.

In the case of the G, you're going to be 5k+ the whole time, with the majority being over 6k.

The average power under the curve can be mathematically be given as an integral or as thrust.

Remember, more RPM with the same torque means more power. More RPM also means that you can have higher gear multiplication through the tranny and FD while maintaining the same velocity at the top of each gear.


Realistically speaking, in terms of HP, at 4000 RPM, with 300ft/lb torque vs a 250ft/lb torque, you're looking at a 30 hp difference at that one point.

BUT, have you ever looked at uncorrected dyno numbers for the 3/g? They show ft/lbs in the 600-1000 range depending on the gear. The axle ratio MUST be entered to get a ft/lb rating for the engine. Ultimately, what is put to the ground is what matters, and gear multiplication with a higher RPM will give you more output.


Using your example, if the cars were of equal weight and equivilent gearing with regards to the MPH each gear tops out at, the 600 hp car should win with any sensible gears. If the gears were super tall, then I can see the 500hp car winning until you reach higher speeds where hp matters more.

 

Area under the curve? Absolutely terrible.

But wait, gearing allows me to stay over 6000RPM at all times (and over 7k in the upper gears), so the only area that matters is the area that is in use.

If I were to go head to head with alan and we both took off at 4000RPM, I'll get murdered. If we go head to head and we both take off at 6000RPM, then I'll be fine; the power difference at 4000RPM is far greater than the difference at 6000RPM due to his thicker powerband,

 

DaveB, here's another example for you. Purely bench racing.

If someone were to give you the peak HP of a car and its weight and drivetrain layout, you can probably predict it's 1/4 mile time with a reasonable degree of accuracy.

However, if someone were to give you the peak torque of a car and its weight and drivetrain layout, you wouldn't have a clue as to its 1/4 mile time.

 

I understand what you are trying to relay... however, you posted a bad example. Alan's peak hp is 311, mine is 294 (same machine same day) - Alan’s' peak trq is 255 (or so) but his mean trq avg is only 211 (or something crazy low like that) - my peak trq is 261+ and mean trq avg is 245.

I've raced Alan at the drag strip and beat him twice... first run was ahead from the start (till the end) - low end trq helped and decent hp kept me there... in a 2nd run I was trying some different launch techniques and had a crappy 60' time - he was .1+ seconds faster 60' but I reeled him in and my ET ended up being faster.

Never underestimate trq, ever.

back to topic though... 335i beats G stock... and beats G modded with a fraction of the $$$.

Moral of story - WGAF.

 

This plot is from a REVUP engine but it illustrates the usable RPM range of gears 1 through 4 in a 1/4 mile race.

The thing to take from it is this:
1st gear average RPM ~4700
2nd gear average RPM ~5600
3rd gear average RPM ~6000
4th gear average RPM ~6000

Changing the final drive won't really change any of the gear RPM averages except for one... (4th gear) where it will be a little higher because the finish line will be crossed very near redline.

With a taller final drive, 4th gear will average about 6250 RPM.

 

EDIT:
Note, the entry and exit of gears 1-3 are unchanged by a taller final drive because the entry and exit of each gear is determined by
1) the RPM limiter of the engine
and
2) the differences in transmission gear ratios.

The entry to 4th remains unchanged but the average is higher because the race ends at about 7000 RPM rather than the usual 6125 RPM.

 

Not really trying to start another one of these 335 v G wars, but I could care less about all these dynos. I've seen them all. Ultimately, the 335 is much faster than the G. Modding might help make up some difference but there's too much torque available for most of the rpm range.

 

Oh come on... you know you dyno higher than that with good gas

His average torque is a bit higher than that... just eyeballing he should be 225-230ish. I'll go run it on my laptop later.

Also keep in mind, that he was on some HEAVYASS 20's, while you're not, which is not reflected on Church's dyno. His drivetrain loss is enough that he'll lose to a stock G on 17's. He noted noticeable response changes when we got the Volks. He's also now faster than a stock G

Plus, you have the benefit of having Shawn tinkering around on your car

I'd love to see how you do against a 09 sedan; have you been at the strip since the latest mods? Shifting the powerband up is

 

The 335 has 300 lb/ft of TQ at 1400 RPM. the G doesn't even develop that much period.

 

Don't know how to paste a .pdf file, but I have a calc that shows force to the ground for each car based on their gear ratios and posted dynos. The higher rpm advantage of the G really doesn't come into play until after 60 mph. If anyone can explain how to post this, I will.

Regardless of these numbers, I feel that my 335 has much more pull at all speeds. And lag is not existent as far as I can tell. Gas and go is all it feels like to me. If it is there, it is not perceptible. That's just my experience from owning both cars.

 

I agree. I was responding to the assertion that the acceleration of these 2 cars is close enough to be made up by a few mods.

Both cars are fast enough for the street anyway, so the point is useless.

 

Again, I state that the 335 has much more useable power. In a drag race, the meatier powerband won't matter because only the upper end will be used.

Okay the 335 is rated for 300 ft/lb of TQ at 1400 RPM. Nice for daily driving. Means absolutely nothing when you're flooring it.

A 1st gen G idles more torque than my s2k peaks. If both cars are caught in the wrong gear, the s2k is still toast. The G's powerband is so much bigger that it'll eat the s2k. In a drag race, it's a driver's race.