Power at the wheels

[Gary]

Hey guys,
how are we? Just wondering what sort of power figures other teams are getting. We achived about 50kW at the wheels @ 9500rpm. does this sound like its in the ball park?

also has anyone ever had a problem with their engine (ours is F4) not idling below 3000rpm?

Also while i am here where can you find accelerationa dn skid pad actual times (not points) set at the competitions?

all the best

[james17]

I dont know to what extend your motor has modified but we actually had a motor that ran extremly lean like, had bizzare rev charecteristics, and would not run at all below about 3000 RPM. Upon disasembly we found that the cams had been reinstalled with some components 180 degrees out. Sound possible ?

[Frank]

50 is ok

idle below 3000 difficult, depends on throttle size, you can "force" an engine to idle at a certain rpm by putting a "hollow" in the timing map at zero throttle

4.05 is good for acceleration (i think the best ever is 4.02 by cornell)

5.15 is good for skid pan (not sure what the record is)

[Eddie Martin]

Gary,
50 kW is more than adequate if it is very driveable and you get good fuel economy.

I think Ohio State hold the record for the acceleration event. Talking to some of the guys on the team they did a 3.9 at a comp and have done 3.7 in private testing. (I may be wrong on this though).

I'm also pretty sure someone has gone under 5 seconds for the skid pan at a competition as well. Can't remember who it was.

[Mad Ruska]

I can remember that Penn State run under 4 sec over the old distance of 94 m (100 yard) 2000 in UK. I think it was around 3.94

I have it on Video somewhere.

[Bulldog R]

We hit 60hp on the dyno at competition with a map that could have used some more tweaking.. What numbers did all you see on the dyno at comp this past may?? We ran an f4i on e85, no internal engine mods.

[Charlie]

The dyno at competition was smoking crack if I remember correctly. http://fsae.com/groupee_common/emoticons/icon_wink.gif

[Denny Trimble]

Yeah, multiple varieties. I heard of at least 3 different "calibrations" that were run on it, giving numbers from 60 to 109 HP.

That's Nucking Futs!

[Michael Jones]

Dyno at competition was really low, with a billion excuses why. 77hp, but we expected considerably more.

Ohio State's 3.75s (something close to that) in acceleration in 2001 still's the mark to beat, and Cornell's 2001 skidpad of 5.083 the same.

No official sub-5s yet, although Cornell's done many in practice. 2002 weather was way cold, 2003 was done wet, and the 2004 car never really pulled too many sub 5's compared to them. It's doable, but the conditions have to be right.

[Charlie]

The dyno wasn't low. It was all over the place! Not to be trusted... I think they were showing 120+ for awhile. They were asking teams what they 'usually' dyno at to try and calibrate it. Not a good PR stunt for sure.

[BeaverGuy]

I thought you guys(Cornell) hit 96HP. That is what I thought the output said.

[John Bucknell]

Don't even get me started on dynos. Inertia dynos are notoriously 'variable' due in part to the inability to calibrate them. We see upwards of 20% error on inertia dynos relative to the motoring AC brake dynos we use. Also, beware anytime a SAE correction factor above +/-4% is used - the atmospheric density correction isn't valid above that.

They are useful for generating loads for calibration, but not good for absolute numbers.

[Michael Jones]

I do remember a few 100+ HP numbers early in competition...this was fixed though, leading to the opposite problem of excessively low numbers.

I didn't catch all our run myself, but we expected mid-90s at the crank, mid-80s at the wheels, and I'm pretty sure we hit 77. From what I've heard, everyone's scores later in the competition were off about 15% or so from what they expected, so that's about right.

[Jon Huddleston]

I agree with Charlie's comments above. I must admit we had some fuel tuning problems, but I believe our first run was close to 100hp if not over, then dropped to the 50-60hp range on the later runs. All runs showed an almost linear power curve though.

P.S. Do not forget about voltage compensation in PerTec's fuel tables, or eliminate it all together, and do not mount your rectifier anywhere near the exhaust system. That is the reason behind UTA's poor performance in the acceleration event and almost kept us from running the autocross at Detroit this year. The car kept running richer as the rectifier cooked.

[Frank]

i swear guys (sips beer...) it was THIS BIG

http://fsae.com/groupee_common/emoticons/icon_wink.gif

[Mark Peugeot]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by james17:
I dont know to what extend your motor has modified but we actually had a motor that ran extremly lean like, had bizzare rev charecteristics, and would not run at all below about 3000 RPM. Upon disasembly we found that the cams had been reinstalled with some components 180 degrees out. Sound possible ? <HR></BLOCKQUOTE>

Yes, it's entirely possible. I know, I was the person who found the cams 180 out (or as one smartass put it, 900 degrees out.) I wouldn't have caught it if it were not for Ben, he pointed out that cylinder one was the exact opposite side of where most automotive engines put it. I just hope no valves were damaged.

Mark

[Mark Peugeot]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by John Bucknell:
Don't even get me started on dynos. Inertia dynos are notoriously 'variable' due in part to the inability to calibrate them. We see upwards of 20% error on inertia dynos relative to the motoring AC brake dynos we use. Also, beware anytime a SAE correction factor above +/-4% is used - the atmospheric density correction isn't valid above that.

They are useful for generating loads for calibration, but not good for absolute numbers. <HR></BLOCKQUOTE>

How True!

Every dyno on the planet reads different (or so it would seem!)

Mark

[AndyPate]

We eventually got our F4 to idle at about 1800rpm by tweaking the engine map, we use a M4 motec unit.
Does anyone else have a problem with power below 3000rpm?? There is nothing there then all of a sudden it hits 3000 and its away.

[Charlie]

Never really paid attention to power below 3000 RPM. If youe engine ever sees under 3000 RPM with the car rolling, someone screwed up. http://fsae.com/groupee_common/emoticons/icon_wink.gif

[Andy Pate]

True ..... our rear sprocket was the size of mars, slightly too much torque at the wheels!!