More N55 info

[bmrm396]

^^^ if this is tru i may have just wet my pants!

[LaCroix]

I have no idea whether to get a brand new n55 or go for a used n54 . I picked the worst time to buy a bmw, lol.

[ennislaw]

Originally Posted by NYC6

I dont know about you guys but I really dont need or want peak TQ at 1200rpm! I really dont understand why thats a selling point.

If it's like the N54, the power will peak at 1200 but the power curve stays flat until it drops (and HP takes over) at much higher rpm, about 5200 rpm for the N54. It means you have full torque available throughout an entire rpm range, quite a feat for BMW! I love driving the 135i, even with MT it's a treat to use that broadband of torque around town.

pge

[BrokenVert]

Originally Posted by ennislaw

If it's like the N54, the power will peak at 1200 but the power curve stays flat until it drops (and HP takes over) at much higher rpm, about 5200 rpm for the N54. It means you have full torque available throughout an entire rpm range, quite a feat for BMW! I love driving the 135i, even with MT it's a treat to use that broadband of torque around town.

pge

What are you talking about full torque through the whole powerband?

This engine doesnt have a 5200 RPM redline it has a 7K redline...I hate the cliff that the torque jumps off of after 6K.

[ESC OFF]

Originally Posted by DBFIU

Since when do you go down to 1200 RPM on a track?

Pit stop

[ennislaw]

Originally Posted by BrokenVert

What are you talking about full torque through the whole powerband?
This engine doesnt have a 5200 RPM redline it has a 7K redline...I hate the cliff that the torque jumps off of after 6K.

Obviously, the torque curve and hp curve are different. On the N54 the torque drops from full output at about 5200 rpm; meanwhile, the hp is increasing. Generally you use hp beyond 5200 rpm, not torque (and I'm unaware of a situation where you'd need torque at 7000 rpm). And I know the redline isn't 5200 rpm. You should look at a torque/hp graph of the N54.

pge

[BrokenVert]

Originally Posted by ennislaw

Obviously, the torque curve and hp curve are different. On the N54 the torque drops from full output at about 5200 rpm; meanwhile, the hp is increasing. Generally you use hp beyond 5200 rpm, not torque (and I'm unaware of a situation where you'd need torque at 7000 rpm). And I know the redline isn't 5200 rpm. You should look at a torque/hp graph of the N54.

pge

Are we driving the same car? The car just falls flat on its face above 6K and cliff of torque is responsible.

The last time I checked HP is a function of Torque...without torque there is no HP.


Here is a stock N54 dyno chart...look at what happens after 5K, torque and HP dropoff

[SlicktopTTZ]

Originally Posted by ennislaw

Obviously, the torque curve and hp curve are different. On the N54 the torque drops from full output at about 5200 rpm; meanwhile, the hp is increasing. Generally you use hp beyond 5200 rpm, not torque (and I'm unaware of a situation where you'd need torque at 7000 rpm). And I know the redline isn't 5200 rpm. You should look at a torque/hp graph of the N54.

pge

Not to sound like a dick, but you need to do more research into how to interpret a dyno chart and how torque and horsepower relate to each other.

[ennislaw]

Originally Posted by SlicktopTTZ

Not to sound like a dick, but you need to do more research into how to interpret a dyno chart and how torque and horsepower relate to each other.

I won't comment on the dick part, but the torque curve on the N54 is flat from 1500 to about 5200 rpm according to the chart supplied by BMW. HP goes on to peak around 6k rpm or maybe slightly earlier. Of course, the torque drops off at the point or earlier as it does on just about every other motor I know about.

What's your point?

pge

[crzy4135i]

Originally Posted by ennislaw

I won't comment on the dick part, but the torque curve on the N54 is flat from 1500 to about 5200 rpm according to the chart supplied by BMW. HP goes on to peak around 6k rpm or maybe slightly earlier. Of course, the torque drops off at the point or earlier as it does on just about every other motor I know about.

What's your point?

pge

Why do you even care if you're walking everywhere?

The point is it would be nice to maintain a flat torque curve all the way to redline so the car pulls hard all the way to redline..

BMW chose to size the turbos for low end torque. They can't support the airflow required to maintain the same boost to 7k. I don't really like it but after driving the car for two years I enjoy having the low end torque for daily driving.

My S4 has plenty of top end boost with GT28 turbos but no boost below 3600 rpms. Everything is a compromise but I'm pretty sure most people would rather have low end torque for a daily driver. That doesn't mean they still can't complain about how they miss the upper end torque.

[ennislaw]

Originally Posted by crzy4135i

... Everything is a compromise but I'm pretty sure most people would rather have low end torque for a daily driver. That doesn't mean they still can't complain about how they miss the upper end torque.

The US is a lucrative market for BMW and outside the M-series, I suspect the number of drivers who track those cars are next to nil. The anomaly is an unknown percentage of 1-series drivers. I think it would be great if BMW offered a track package for the 1-series here, it seemingly would meet the needs of those folks who want to track and those who feel the need to drive a track spec'd car on the public roads for whatever bizarre reason. I suspect almost all BMW users would prefer the lower torque for daily driving, as you point out. And I seriously doubt BMW will change that.

The point I was trying to make is the current power/torque curves are more than adequate for driving on public roads. Perhaps not sufficient for drag strips or tracking, but that's a totally different purpose. And I'm aware there are a few who want to use their DD for the track on the weekend, probably not the best of both worlds there and they'll just have to accept those compromises.

This forum appears to do a great job allowing members to express their opinions, disagree with others' and to just plain ventilate, in addition to providing an incredible amount of useful information from those same members. I think that's great, so everyone on this thread should be feeling much better now.

pge

[garmboyz_nat]

Does anyone know what type of turbo they used? I know it's twin scroll, but would like to know if it TD04 or so?
Thanks in advance.

[mra]

Originally Posted by garmboyz_nat

Does anyone know what type of turbo they used? I know it's twin scroll, but would like to know if it TD04 or so?
Thanks in advance.

Borgwarner but I don't know what model..

[garmboyz_nat]

Originally Posted by mra

Borgwarner but I don't know what model..

Thank you.

[bradleyland]

Originally Posted by maxnix

Yes, "dyno" runs that predict HP are just that, guesses. Most cannot determine what true crank torque is, much less wheel torque under real world running conditions.

Stationary with the hood up and the powered tires on rollers is not real world.

Are you kidding? You should read a physics book. A dynometer doesn't "predict" anything, it measures force. If you know the force that is exerted at any given RPM, you can calculate the horsepower being produced. If anything, a crank dyno reading is less relevant for real world application than a wheel dyno, because the crank dyno can't predict driveline losses. For comparing car to car, apples to apples, a wheel dyno is far more effective. Granted, you need to run both cars back to back on the same dyno for the purposes of direct comparison, but a dyno is a very effective tool for assessing the real output of your modifications.

[bradleyland]

On the topic of torque vs horsepower:

As TrackRat has already so eloquently put, one is a function of the other. Ultimately, horsepower is the number you should be concerned with if you're after performance, and more specifically, the curvature of horsepower production. Peak horsepower is an interesting number, but if you look at a lot of dyno charts, you'll find that a strong performing car has a dyno chart that rises early, stays strong, then drops after its peak. As far as performance goes, torque numbers aren't terribly important.

Why is that? Because for any specified horsepower output, you can generate equal torque through gearing. That is to say, two engines that generate 300 HP at a given RPM can generate equal torque at any given RPM. An example using the following formulas:

hp = tq(rpm)/5252
tq = hp(5252)/rpm

Engine 1
300 HP @ 5000 RPM

Engine 2
300 HP @ 8000 RPM

Q: Which of these engines, when operating at peak HP, is capable of producing more torque at 2500 RPM (through a gearbox)?

A: Neither, they would both produce roughly 630 lb ft through a gearbox (unaccounted for loss). Engine 1 would require a gearing factor of 2:1 and engine 2 would require a gearing factor of 3.2:1. Since both engines must operate through a gearbox, both will suffer losses and we can assume any discrepancy between gearboxes will be negligible.


This is why tq vs hp doesn't matter. With the appropriate gearing, you can apply the same force at the ground. Torque is a measure of force only. I can generate 400 lb ft of torque with a torque wrench. If you put me under the hood of your car with that torque wrench attached to the input shaft of the transmission, how fast do you think you'll go?

If you want to go fast, you need lots of horsepower. End of story.

[sleeper001]

Hello i am new here, just bought a brand new 2011 and the sales guy didnt even know anything about the new N55 engine plus in the details that was posted on the car it still says twin turbo....what the hell???

[bradleyland]

Originally Posted by TrackRat

Well sort of...

Torque is what accelerates a car so you can't just look at peak HP and assume that gearing will deliver the same acceleration even though the peak wheel torque/HP may be the same.

If you use more gearing via the trans or diff, then you need more engine rpm or your top speed is limited. You'd also need an engine thet revs very quickly, especially in the lower gears. So the bottom line is you want to have the maximum torque in the rpm band where the engine will operate.

My example takes a static moment in time (which admittedly is pretty useless ) to illustrate a point. That is that HP is a function of torque, and using gearing, you can move the torque production around where needed. That doesn't necessarily express the flexibility of the engine. Take, for example, a diesel engine. They produce a lot of torque over a narrow RPM range, and therefore don't make very good sports car engines. Then again, more recent diesels are solving these problems, so I'm stuck with more bad examples

My bottom line is, I agree with what you said, 100%. It's just frustrating to read conversations where people (not you) talk about torque and horsepower as if they're two distinct measurements, and that engines either have one or the other.

[crisart]

I just got 2011 135i dual clutch trans and I am wondering if anyone has taken one down the 1/4 and if they make any parts for it ?

[bradleyland]

Originally Posted by maxnix

No, no parts. Engine sealed for life. Racing voids warranty and BMW monitors every track.

I was wondering what the blacked out 5er was doing camped outside my house for the last few days. I've always had a suspicion I was under surveillance

[MarkR171]

Originally Posted by bradleyland

I was wondering what the blacked out 5er was doing camped outside my house for the last few days. I've always had a suspicion I was under surveillance

You have one tailing you too??

[sleeper001]

Originally Posted by maxnix

No, no parts. Engine sealed for life. Racing voids warranty and BMW monitors every track.

no parts are out as yet because it is a new motor and test for compatiable parts/new parts just got started i would imagine...