Portland Dyno Day results; My BBSC details

[Lud]

Still, would it be possible to see that much HP increase on temperature alone?

No. HP numbers published by the manufacturers are supposed to be rated at sea level and around 70 degrees F. A rough rule of thumb is about a 1% power difference for every 10F change in temperature. Excessive humidity reduces power slightly because the water vapor displaces oxygen in the same volume of air. Ignoring the humidity, you'd need it to be around 30F just to see a around a 10HP gain in HP. The stock car numbers look a good 35-40 HP high.

Granted there is variation in dynos, yada yada yada, but when you are measuring a stock NSX with 15 more HP at the wheels than the car is rated for at the crank, you need to re-evaluate your measurement process.

If you subtract 35-40 HP from the stock cars to get them down where they should be, then subtract the same from Roy's car his numbers would be down in the 265-270 range. He's got a major issue if his Novi is generating even 4 PSI and he is only seeing around 270 to the wheels.

 

[6061-T6]

Dyno Information

I got some more information from the dyno owner/operators:

They calibrated the dyno with a VW GTI VR6 several weeks ago. They have not run many 2 wheel drive cars since then. My theory is the calibration is probably off. Notes – The VW GTI VR6 typically produces 150-155 hp at the wheels. The calibration file for 2 wheel drive mode is different than the calibration file for all wheel drive.

The dyno includes inputs for ambient temperature and for humidity. These were put in the dyno once, at the beginning of the day. So the figures above are “corrected”.

The dyno is a load dyno rather than an inertial dyno (like the dyno jet). I don’t know if this means anything for the test that were run.

My other theory is the A/F readings for the day are all richer than measured/reported. I don’t know why. If this theory is correct, then my car is really rich, rather than titaniumdave’s car being really lean, which could partially account for my low power. Morgan currently has my car for it’s over due 6 year + 15kmile service.

Assuming the dyno is “mis calibrated”. And assuming 240hp would be “normal” for a stock 3.0 liter relative to a dynojet reading. How should the other numbers be adjusted for the mis-calibration? To try and equate to a dynojet, should we subtract the same constant “offset” number from everyone’s results, or should we use a linear adjustment.

 

[peiserg]

well, if 240 whp is normal for your 3.0, then 306 is still 65 hp more than stock... yeah, not quite what i'd expect from the bbsc since others have seen over 100 whp, but certainly on an otherwise stock 3.0, 300+ is much higher than it was before? And you did gain 18 hp from the improved .3 psi boost, so if you are really running short of the 6.0 psi you'd expect, then figure out where that boost is going, and i'd bet you'll make another 25-50hp if that .3 gave you 18hp...

 

[Lud]

Re: Dyno Information

Assuming the dyno is “mis calibrated”. And assuming 240hp would be “normal” for a stock 3.0 liter relative to a dynojet reading. How should the other numbers be adjusted for the mis-calibration? To try and equate to a dynojet, should we subtract the same constant “offset” number from everyone’s results, or should we use a linear adjustment.

I don't think it's possible to say unless you know what caused the error -anything else is just going to be applying arbitrary corrections to the numbers to make then look the way you think they should.

If you have reason to believe that both the power and the air/fuel readings are wrong, I think you just need to scrap these results and have a new dyno day somewhere else!

 

[Track Junkie]

You can check to see if it is spinning by marking a line across the pulley and the belt. Take it for a few hard runs and check if the line still matches. If it doesn't tighten or replace the belt.

Recently my belt was squealing so I tightened it and then drew a line as you mention. I'm almost certain my belt was no longer slipping, yet the lines failed to match up after a short test run.

I question whether this is a reliable method of determining if the belt is slipping. Doesn't this depend on the length of the belt being an even multiple of the circumference of the pulley?

 

[Turbo NSX]

I would suggest to mark it and then start the engine, don't revit just let it idle. Turn it off and see if it still matches. Then take it for a ride and see if it still matches. I would think if the belt doesn't slip it will always hit the same spot. Post what you find out. I am kinda curious now.

 

[NSXTASY_MD]

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collapse;table-layout:fixed;width:573pt'> <col width=56 span=2 style='width:42pt'> <col class=xl324005 width=56 style='width:42pt'> <col class=xl334005 width=56 style='width:42pt'> <col class=xl284005 width=56 style='width:42pt'> <col class=xl224005 width=56 style='width:42pt'> <col width=428 style='mso-width-source:userset;mso-width-alt:18261;width:321pt'> <tr height=17 style='height:12.75pt'> <td height=17 class=xl264005 width=56 style='height:12.75pt;width:42pt'>Name</td> <td class=xl264005 width=56 style='border-left:none;width:42pt'>Year</td> <td class=xl294005 width=56 style='border-left:none;width:42pt'>HP</td> <td class=xl294005 width=56 style='border-left:none;width:42pt'>TQ</td> <td class=xl264005 width=56 style='border-left:none;width:42pt'>SC</td> <td class=xl264005 width=56 style='border-left:none;width:42pt'>Milege</td> <td class=xl264005 width=428 style='border-left:none;width:321pt'>Extra</td> </tr> <tr height=17 style='height:12.75pt'> <td height=17 class=xl234005 style='height:12.75pt;border-top:none'>Roy</td> <td class=xl234005 align=right style='border-top:none;border-left:none' x:num>1995</td> <td class=xl304005 align=right style='border-top:none;border-left:none' x:num>306.0</td> <td class=xl314005 style='border-top:none;border-left:none' x:num>214.0</td> <td class=xl264005 style='border-top:none;border-left:none'>BBSC</td> <td class=xl254005 style='border-top:none;border-left:none' x:num="32340">32,340</td> <td class=xl234005 style='border-top:none;border-left:none'>4.3lbs boost,
rich, belt loose</td> </tr> <tr height=17 style='height:12.75pt'> <td height=17 class=xl234005 style='height:12.75pt;border-top:none'>Roy</td> <td class=xl234005 align=right style='border-top:none;border-left:none' x:num>1995</td> <td class=xl304005 align=right style='border-top:none;border-left:none' x:num>312.4</td> <td class=xl314005 style='border-top:none;border-left:none' x:num>217.8</td> <td class=xl264005 style='border-top:none;border-left:none'>BBSC</td> <td class=xl254005 style='border-top:none;border-left:none' x:num="32340">32,340</td> <td class=xl234005 style='border-top:none;border-left:none'>Bypass VVIS
4.3lbs boost, rich, belt loose</td> </tr> <tr height=17 style='height:12.75pt'> <td height=17 class=xl234005 style='height:12.75pt;border-top:none'>Roy</td> <td class=xl234005 align=right style='border-top:none;border-left:none' x:num>1995</td> <td class=xl304005 align=right style='border-top:none;border-left:none' x:num>323.5</td> <td class=xl314005 style='border-top:none;border-left:none' x:num>224.8</td> <td class=xl264005 style='border-top:none;border-left:none'>BBSC</td> <td class=xl254005 style='border-top:none;border-left:none' x:num="32340">32,340</td> <td class=xl234005 style='border-top:none;border-left:none'>changed map, VVIS
stock 4.6lbs boost</td> </tr> <tr height=17 style='height:12.75pt'> <td height=17 class=xl234005 style='height:12.75pt;border-top:none'>Dave</td> <td class=xl234005 align=right style='border-top:none;border-left:none' x:num>1993</td> <td class=xl304005 align=right style='border-top:none;border-left:none' x:num>363.7</td> <td class=xl314005 style='border-top:none;border-left:none' x:num>253.3</td> <td class=xl274005 style='border-top:none;border-left:none'>CTSC</td> <td class=xl254005 style='border-top:none;border-left:none' x:num="37100">37,100</td> <td class=xl234005 style='border-top:none;border-left:none'>CT headers, CT
exhaust, CT intake, K&N filter</td> </tr> <tr height=17 style='height:12.75pt'> <td height=17 class=xl234005 style='height:12.75pt;border-top:none'>Dave</td> <td class=xl234005 align=right style='border-top:none;border-left:none' x:num>1993</td> <td class=xl304005 align=right style='border-top:none;border-left:none' x:num>368.2</td> <td class=xl314005 style='border-top:none;border-left:none' x:num>258.4</td> <td class=xl274005 style='border-top:none;border-left:none'>CTSC</td> <td class=xl254005 style='border-top:none;border-left:none' x:num="37100">37,100</td> <td class=xl234005 style='border-top:none;border-left:none'>CT headers, CT
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Dude, those stock 93's are putting down 302 and 283 RWHP ???? Something's not right there! Isn't that like 20-to-40 RWHP too high from an essentially stock 3.0 ??

 

[Yellow Rose]

I would think if the belt doesn't slip it will always hit the same spot.

I initially thought this as well; however,.....

Doesn’t this depend on the length of the belt being an even multiple of the circumference of the pulley?

.....this is a correct statement.

Just this past weekend I marked a point on the belt and a corresponding point on the pulley, started the engine in the driveway, let it idle and turned the engine off. The marks did not line up anymore.