and again. tab key still doesn't work in here.

the next one is for real.

These three posts have been edited, if you didn't catch on any faster than I did.

 

Soul,

Yes and yes.

The engine is making more power with colder ambient air for two reasons.
1. Colder air going into the supercharger means colder air coming out.
2. Colder air coming through the scoop and flowing past the
intercooler makes it is more effective, thus further lowering the
temperature of the air going into the combustion chambers.

Colder temperatures also reduce tire grip, though snow tires aren't impacted as much as the tread compound is designed to work at lower temperatures. All season tires lose some grip and summer tires lose even more.

I get some mild wheelspin starting around 3500rpm during a roll-on too, but the Quaife really makes a difference. The car is still accelerating strongly and the tires certainly aren't smoking. Do you have an open diff.?

Scott
90SM

 

yeah i have the open diff, it does kinda feel like the left tire looses traction a bit before the right. i also have the stock 16inch run flats, im sure they arent the best for traction either, but anyway it sure is faster.

 

- 2003 MCS
- 205/45-16 T1Rs on 16x7 Rota Slipstreams
- Rear seats removed
- WMS Head, 15% Pulley, JCW DME w/ Unichip (Ramp 6), JCW Airbox, 380cc injectors, Milltek header and Catback, Schrick cam
- 48 degrees
- Elevation = 250ft
- New section of unopened freeway - level pavement
- 7 runs


5.77
5.61
5.80
5.84
5.89
5.76
5.71

 

Nice numbers....which cam 264/272?

 

Yes.

 

I just came upon this thread (been out of country for a while), and am very interested in doing this!! Tonight it's going to be about 16*F outside, and tomorrow during the day about 30*F or so. Which temp would be better to do the test in?

 

The lower the ambient temp, the quicker your time. I don't know how to correct for temperature or altitude though. That would be neat test for you geeks out there

 

Cool thread, reminds me of JCW's response to an email of mine. I questioned dyno WHP reading and they said that wasn't a good measure and that if I wnated a good measure time to distance and similiar runs like discussed in this thread.

If it doesn't make you faster on the road what good do other numbers mean?


Paul

 

See...there are smarter people than Andy besides us

 

That's what I was wondering about, since it doesn't seem that we have math nerds on hand, I can only assume that doing it at 30*F would be a better comparison to the rest that have posted. I'm sure I'll do it tonight anyway .

 

Time - 00:38
Temp - 8*F
Altitude - 581.2 feet (milwaukee, wi)

5 pulls w/ my timex ironman wristwatch, and me in the car.
1/2 tank of gas, long flat stretch of I-94.
3500 rpm 3rd gear pulling to 6000 rpm.
2005 MCS, 16% M7 pulley, HAI, H-sport springs, riding on 15" steelies w/ 195/55/15 Pirelli Snowsport 210's.

1- 4.67
2- 4.82
3- 4.71
4- 4.92
5- 4.73

Ok...I'm a bit faster than the results I've seen so far. Gearing? Temp? I'm going to take a vid with my camera after this post for proof. BRB.

 

Alright I ran a fresh 3 sets and got them all on vid (with my sd400). The 3rd got lost because I tried to edit it on the camera, and trashed the part I wanted to save, I left the rest for movie maker. I also added a vid of the boost, which peaks at about 17lbs.

It was still 8*F outside when I did these runs.

Run1
http://www.we-todd-did-racing.com/we...EzZGZkMzF5NTQx

Run2
http://www.we-todd-did-racing.com/we...EzZGZkMzF5NTQx

Boost
http://www.we-todd-did-racing.com/we...EzZGZkMzF5NTQx

 

Pretty damn good 8F sure helped a hella lot

 

Well, Coop d'etat has a 2005 MCS with lower gearing than the pre-2004 models and is running 195/55-15 tires (which have a smaller overall diameter than stock).

Take his times * (24.3/23.4) * (5.937/5.651) = 1.09

So, even if Coop d'etat's car has the EXACT SAME whp as a 2003 MCS with stock sized tires, his 3500-6000 time in 3rd gear will be MUCH shorter (half a second or more!). Add this to the huge variation that all users will encounter due to hand-eye coordination, tacho error, driving on inclines, etc. and I don't see how this type of measurement has any repeatability or standardization at all.

You end up with pundits believing that the reason one number is lower than another is strictly due to temperature, etc. when in reality there are far more significant factors throwing off the results.

 

I knew you'd figure this out first Good points

 

My thinking exactly, sure glad we both woke up on the right side of the bed.

 

another reason to measure speed to speed.

 

I just thought it was a fun thing to do...I never thought that it would somehow measure my Hp compared to other cars. The neat thing was that in movie maker, you could go frame, by frame and mark the exact time when the needle moved, and the exact time it hit 6000rpm. So if everyone took video, we could get accurate times, but so many other factors (tires, wheel size, slight incline, slight decline, temp, altitude) come into play that there would be no real way of figuring what the exact hp was.

The real problem I see is that aside from everyone using the same dyno, Hp figures will always be a non-exact number. I've seen two different dynos read 13hp difference on the same car, on the same day (260hp car, or 273 ). 1/4 mile times are just as flawed...In that case you are pitting a drivers skill+car, against another driver+car...the car's mods play less of a role once you put human reaction times, and shifting speeds into play. If you look at andy's 1/4 mile time chart you will find cars with minimal mods, running with the same 1/4 times as those cars that 'should' run much quicker in the 1/4.

The question is, when the dyno, track, and 3.5-6k run, are used as a comparison when you add a new mod are they an accurate measure of power gains?

Track - perhaps. Unless you get the exact same r/t, it's the same temp out as your previous runs (or you know how to correct for that), and you drive just like you drove on your previous runs (thats the kicker...you are the only one to judge that).

Dyno - perhaps. If you upgrade during the same day, w/in say an hour or two of your last run.

3.5-6k run - perhaps. If you videotape the tach, and use a program to mark the needle movement (or datalog the rpm), use the EXACT same stretch or road, and take an average of 10 runs or so...I think then you could use it as a benchmark.

All in all, while I don't think Hp figures are a shot in the dark, I do think they are a shot into a dimly lit room.

 

The dyno will give you the best repeatability IF you properly control the environment. That's what SAE correction factors are for. But you have to log a lot of data that most don't so that you know the car is in the same state for each run.

The same track will then be the next best. And you can correct for the ambient differences (see TonyBs post on page 1 of this thread).

This rolling measurement will be the least repeatable, even if times can be measured accuratly.

That said, if you take this for what it's worth and don't read too much into it, everyone will have some fun.....

Matt

ps, I'm using a G-Tech and BiM-COM, the same stretch of road for my HP runs. The absolute number is way off (157 HP or so), but the repeatability is amazing! This allows me to do part comparos with a high degree of confidence, but the absolute number I get is worthless. It's more usefull as a percentage, but it does let me compare mods.

 

Same here Matt and I agree

 

Dr. O, I think you said it best in your post... "IF".

 

Did mine on the way to work today.
Temp: 24F
Elev: 4000

Run1: one mississippi, two mississippi.....err, 7.01
Run2: 6.56
Run3: 6.74

Mods: 15% pulley, Alta CAI, denso plugs.........and 90900 miles

Nik

 

Tested ours out again while in posession of an actual timer of course.

Elev. 100
temp. 60F
Half tank gas + Co. Pilot

3 run avg. 6.82

I'm just glad it's under 7.00

 

So I got new tires, the OEM run-flats were bald on the front, the backs were OK but I got rid of them.
Anyway the new tires are 205/50/16’s as opposed to the 195/55/16 OEM.
My 3500 RPM to 6000 RPM times have changed.

Conditions were very similar to the first time I did the run see below:
• No wind
• 38°F
• 5829 ft above sea level
• <0.5° incline
• 3500 RPM = 47 mph
• 6000 RPM = 77 mph
• 3 passes
o 7.49 seconds
o 7.25 seconds
o 7.62 seconds

Today on the same stretch of road near Double Eagle Airport above Albuquerque:
• Again no wind, or very light winds
• 39°F
• 3500 RPM = about 46 mph (GPS) – did not check 6000 RPM
• 3 passes
• 7.08
• 6.95
• 7.05
Nearly half a second difference?
Must be the tires or the gas (winter gas?), I know my stop watch didn’t change.