DrRick

The homie DS01 wasted NO time seeing what the new whip was putting out. Traded his MINT ISF last weekend and has already put her on the rollers. To hell with a break-in...


Says it put down 388 to the wheels...

4TehNguyen

iTrader: (1)

ISFs were about 360 to wheels sounds about right

DrRick

yeah...and when you see that the BMW's are putting over 400/400 to the wheels (and the weight difference)....its a real credit for the RC-F to be so competitive on the track.

05RollaXRS

Depends on the dyno. You have to remember dynos vary a lot. There were some IS-F that were dyno'ing as low as 333 wheel HP as well. There is almost no way to compare directly two dynos done on different days with different temperatures, different types of dynos (Mustang vs Dynojet) etc.

http://www.automobilemag.com/reviews...-f_dyno_chart/

388 wheel HP, I suspect would be on the lower end. We might see some higher numbers than that.

4TehNguyen

iTrader: (1)

Ms max torque is low like 2-4k rpm, you wont see that rpm on a track. In the high end the torque is weaker

Ryanmcd

can you post a graph?

05RollaXRS

BTW, M4 made 379 wheel HP on the MotorTrend dyno. More importantly, the area under the curve is completely out of whack. Torque curve completely loses steam after 5500 rpm. It is the furthest thing from the gold standard "flat torque curve at high rpms" these days.

At 6500 rpm, it already has dropped to 78% of its peak available torque. By 7000 rpm, it further drops to 71% of its peak torque. It is reminiscent of diesel engines at how the make gobs of torque down low, but rapidly gas out at the higher rpms.

http://www.automobilemag.com/feature...heels-on-dyno/

DrRick

disagree...the low end torque will allow you to not have to shift as much to keep the rpms in their 'sweet spot'. good low end torque is never a bad thing. and in the higher rpms is when the horsepower takes over....

eoph

higher rpm lets you take advantage of gearing too, else sports cars would have diesel motors.

05RollaXRS

This has been discussed extensively in another thread. There is no such thing as "horsepower take over". Horsepower is merely measure of torque at high rpms. It is extrapolated from torque relative to rpm. That is it. That is the old muscle car thinking that only low end torque matters.

The M4 engine completely gasses out after 6500 rpm. That is the simple fact. That is because BMW opted to minimize turbo lag by fitting very small turbos that great gobs of torque down low, but run out of breath as the rpm climb up.

It is about the area under the entire curve. Not just a small segment.

The mathematical equation is:

HP = torque x rpm / 5252

Torque is what turns the wheel. HP is completely meaningless. Torque curve all across the rev range matters. Not just low end.

FYI, racing engines spend billions of dollars in R&D to make the engine produce as close to peak torque all across their rev range. They are not all foolish companies. I can give you explicit examples, if you need further clarification.

If a car makes 500 HP and 400 ft-lbs and another car makes 400 HP and 400 ft-lbs of torque.

That means the engine making 500 HP produces far more torque at high rpms (and hence higher horsepower extrapolation). The 400 HP engine makes the same/more torque at low rpms, but loses steam at higher rpms.

DrRick

true....

10char

Joe Z

iTrader: (10)

This is spot on based on all the R&D I've collected over the last 7 years...

The 8 speed transmission & driveline is good for approx 17% loss to the wheels.

Soo 467 HP equates to 388 Rwhp.

Assuming this was done in 6th gear.. It's a great run..!!


Joe Z

05RollaXRS

Read my previous post. With DCTs these days, 7 gears available with 6th and 7th for overdrive, there is more than enough ratio spread available to gear the 1st - 5th short even with a 6500 - 6800 rpm redline without sacrificing max speed/gear.

High redlines are typically placed for only one reason - the engine can make close to max torque at high rpms, which is why the usable torque is exploited for maximum power.

BMW put a 7500 rpm redline because they did not want to deviate from "high-revving" marketing ploy. No other rational explanation.

Case in point, the M4 engine gassing out after 6500 rpm is a deficiency because of the small size of turbos in order to reduce the lag. It is a well known fact, small size turbos don't breathe well at high rpm. The powerband lies in the midrange for the M4.

Regarding your diesel comment, the modern diesel engines these days can rev as high as naturally aspirated engine (335d can rev up to 6600 rpm with 300 HP and 425 ft-lbs). The issue is, rapid torque loss at high rpms.

TF109B

Thats why Audi's R18 lmp1 has max revs <4000rpm.

4TehNguyen

iTrader: (1)

would like to see the graph from the RCF dyno as well to compare it with the shape of an ISFs