John,

Jim at Star ran the car and got

P-norm 323.5 bhp
P-eng 305.5 bhp
P-wheel 212.5 bhp
P-drag 89.0 bhp
Torque 295 lbf/ft

The graph shows a good boost curve peaking and staying steady at around 1.3bar.

Thanks again John.

Regards,

Mike

PS
Can't figure out how to attach the scan

 

Thanks. Really pleased with that and does fit with how well it was going on the road

 

Here are the graphs, hopefully !

 

Nice result Mike (& John) Holds the boost well

Just one question, where was the air temperature compensation probe ? 63 deg C

 

I wasn't there I did ask if it was by the radiator and it was denied.

 

Andy,

You'll have to excuse my ignorance but i don't know what you are getting at.

I had asked Jim to run the dyno at simillar conditions on each run, 1st (299 bhp) and 2nd (309 bhp) run the A.T. was 58deg and on the latest (323bhp)at 63deg.

Can you please explain what difference this makes to my final bhp figures.

Many thanks

Mike

 

The temperature compensation is applied to P-eng to give P-norm corrected to DIN specification. A high temperature can inflate the figures a bit.

This temperature should really be the temperature of the air going into the engine. In a hot shed it may go high, but 63C does seem a bit too high. I gather there are reliabilty issues with Jim's masheen that are quite costly and explain some of the figures. Whatever, the end results are conservative by Power Engineering or Well Lane standards.

[Edited by john banks - 9/19/2002 11:14:35 PM]

 

Mike, you taking these figures on to track then?

Won't be on at KH on the 28th as my millionaire status has slightly diminished since my last outing!

 

Well the boy can certainly throw it about so I think he would do well on track

 

You talking about his car or his wallet?

 

 

Mike

The rollers measure P-wheel during the power run, then P-drag is measured during the run down after the clutch is dipped. P-wheel is added to P-drag to give P-eng, this is the calculated flywheel horsepower measured on the day.
P-norm is a figure which is 'normalised' to a standard atmospheric condition. IIRC it is 20C and 1000mbar ie If your power run takes place on a day when the temp is 20C and pressure 1000mbar then no correction factor applies to the P-eng figure and the P-norm will be the same figure.
On a hot day the air is less dense, on a day when the barometric pressure is low the air is also less dense. Less dense air means less power. In order that a cold winter day power figure can be compared to a hot summer day run, there is a compensation factor applied to give P-norm. The hotter the air the greater the compensation.
Your horsepower P-norm (and your torque figure) have been 'normalised' by +7.3% due to the excessivly hot temperature recorded.
This temperature should be that of the ambient air, ideally the air temp right at the air filter inlet. I somehow doubt if this was the case now that Jim has the external air feed to the cooling fans ?
Although I'm sure you are not up to this, some dodgy 'dark side' geezers on this board try to get the temperature probe in a nice hot spot in order to give them a high P-norm and torque figure !!!

hope this makes sense ??

Andy

PS Let me guess your next question ...... Which figure do you believe/compare ?

 

Well I just pick the figure I am most pleased with after each run I like the 295 lbft anyway.

Most of the air temperatures are usually about 40 C from what I have seen before, so not all of the +7% is fudge if we are comparing other cars on the dyno. The PaW is not bad for a VF28 at not mad boost.

[Edited by john banks - 9/19/2002 11:31:57 PM]

 

Andy, would he not be better off investing in an AP22?

As you say yourself, that the figures can be 'manufactured'.

I remember Scoty's second run a while back with water constantly being poured over TMIC, gave him 30 odd bhp extra!

[Edited by Dougster. - 9/19/2002 11:34:55 PM]

 

My P-norm was reduced from P-eng the last time !!! Later noticed that the temp probe was sitting on a shelf in the corner

If I'd had the probe at 63C I would have had over 400 BHP P-norm

New engine bay heaters being installed for next run

AP22....may the 'G' force be with you

 

So many ways to fudge it but we are only kidding ourselves if we run high tyre pressures, probe by the rad, bottles of octane booster, runs with very low gearing.

Should settle on 20mph/1000 RPM or as near as possible for all cars, tyre pressures at 32/28 PSI, measure ambient outside and take that as the correction, make the run length the same as it would be on the road and SUL or Optimax without additives?

 

PAW you can only compare between similarly geared cars

P-eng you can compare on the same day

P-norm you should be able to compare any day as long as the temp probe is in the same place on each run

 

I'm up for that but then my run would be shorter than yours and you would complain

 

Look what I found Figures quite similar from Sam's old steed apart from the extra torque, but this has a VF23 and APS FMIC. Was running 1.35 bar road, but showed 1.2 on the dyno plot. Mike's also had deficit between road and dyno, but smaller - might be differences between Link and JECS boost control (but both leave a lot to be desired).

[Edited by john banks - 9/19/2002 11:49:09 PM]

 

Andy performed an AP22 test on my car days before the last run on RR and got P-norm to within 2bhp.

Admittedly on the rr I did have tyres rock hard and OB.

Happy with 180 P-wheel but is it not the torque figure that we should be wanting to raise? Smaller lighter wheels?

End of the day, I sacrafice some performance for looks, but hey....Thats life!!!!

 

My PaW was down from 255 on AP22 to 205 on the rollers due to soft tyres, boost leak, no OB and heatsoak from insufficient time to cool down before the run. Need to be better prepared next time.

 

You missed another corner John.

 

LOL at Sams plot - cheat, cheat, cheat

John

You would be closer to the AP22 PAW if you ran in 3rd. My 4th = your 3rd and it's bang on every time

Dougster - I sacrifice looks for performance......so does the car

 

Thanks for the feedback guys (Andy, 'fraid you lost me a bit) but just one question, if all runs were done at 58 deg what would my figures be.

I've always thought that the only way to guage performance increase by any mod is to run on the RR in simillar conditions.

Thanks again,

Mike

 

Hee Hee! Flung that one out a long way and caught the biggest fish in the sea!!

I need more go, will possibly able to supply manufactured header tanks, alu bits and possibly kevlar at a price, for any assistance in making my fridge freezer go that bit faster!

Templates required if anything needs made.

 

Dougster,

If you can make it on the 28th you can have some laps (passenge/driving) in the car.

Would appreciate your views.

Mike.

 

Mike why 58 ?

As an approximation the rolling road software will 'give' you an extra 1% P-norm and torque for every 6 deg C above 20 C

Your figure at 58C would be 2-3 bhp less and 2-3 lbft less than at 63C.

If you are comparing your previous runs then best to compare power at wheels in my opinion, assuming you had the same wheels on and same tyre pressure. Ambient conditions havn't changed much in the past month.

Dougster

May have something for you mate other than abuse
Alloy welding ??????

 

Should have an answer by lunchtime tomorrow Andy. Could you mail me more details of what you may want done.

 

Jim tells me that the rolling road should be compensated with charge temperature rather than inlet temperature. Seems odd to me since then a FMIC would not give you any gain from reducing your charge temps as it would be compensated - the only gain would be from lower pressure drop and any extra advance you could run. But this is the way it is apparently.

 

I recall him saying that the last dyno day but don't understand the logic

You could turn up with a car with an undersize intercooler, Dyno 'corrects' for charge temp and you get a figure that tells you what your car would have produced "IF" it had a good intercooler on it ??? That's a bit bollocks is it not ?

Still doesn't explain the guys with FMIC's who 'achieve' a high correction factor to boost the figures/ego !!!