Pelican Parts Forums - Dyno results... I'm missing some HP.

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Will: maybe, but correction factor is unimportant in this case.
His Varioram is off line and his torque-curve exhibits typical "Varioram-is-stuck-in-torque-setting-all-horses-lie-down-and-die-after-5500-revs" behaviour...

Moses: fix that thing, put new chip and let it rip!

Quote:

Originally posted by beepbeep

Moses: fix that thing, put new chip and let it rip!

Yeah!
Go, Moses, go!
I need some 915 images for the "Mechanical Mayhem Files."
;)

Huh?? 915 is still there?? Yuck...

I am getting a RUF chip soon to compare with my Cyntex chip....wanna try one?

Quote:

Originally posted by beepbeep
Moses: fix that thing, put new chip and let it rip!

The DME has a Cyntex aftermarket chip already (from Steve Timmins) I'm not sure if this chip just corrects idle issues from the lightweight flywheel or addresses other issues as well.

Quote:

Originally posted by Moses
The DME has a Cyntex aftermarket chip already (from Steve Timmins) I'm not sure if this chip just corrects idle issues from the lightweight flywheel or addresses other issues as well.

Sounds good. I know that US 993's have another sort of ECU that is much harder to transplant/rewire.

Chipped Euro Varioram 993 mill should at least dyno it's original 286HP minus 9-10% losses...that's 258HP at wheels. Common expirience is that they should touch 300 in that state. You have seen nothing yet...

Good luck!

Most dyno results I have seem to show more like 15% loss from flywheel to drive wheels. There does seem to be a hugh amount of scatter. I have always put that down to the areas outlined by Will F.

15% of 286hp is 31 kilowatts...lot's of heat to get rid of. Most transmission losses for 2WD manual-transmission cars are in 7-11% ballpark. 4WD and slushbox can make it worse...but 9% for 915 box is usual.

No fair mikehttp://www.pelicanparts.com/support/smileys/shake.gif the vram is worth ~10hp and more importantly broadens the power band by enhancing torque over a wider range than normal(as described by BeepBeep). You need to get it hooked up! It's no wonder that the power band is 1k too low. The manifolds never switch to the short stacks for high end performance. It performs per spec at the bottom of the rev range then gets strangled at the top.

I have a statistical analysis of 18 dyno runs on 964 and 993. The avg losss is ~21% w/ euro tests on average showing higher losses and NA losses lower.

15% of 282hp is ~41hp which is ~30.6kw. Yes, it is a lot of heat that's why trans coolers are so popular.

The average that I have personally seen from known solid engines is ~15%

Perhaps someone w/ a more extensive sample space can chime in here. As I have posted and Will Ferch has posted dyno results are meaningless (except for back to back comparisons) unless all data is rigorously normalized per SAE or DIN spec.

I believe the difference in euro vs Na results is due to the differences in SAE and DIN test renormalization algorithms.

Just remembered this relevent and informative site

Dyno Info

Hey guys,

Has anyone measured, on a dyno, the effects of an aftermarket chip?

I would love to see some results.

I am still running the factory chip in mine, but at track day last year I drag raced a guy with almost the exact same early car with a 3.6. From third gear on up his car just walked away from mine. I am pretty sure his is chipped.

I am also concerned about the butterfly in the intake tract opening at full throttle. When I check my vacuum canister, it always has a strong vacuum, but that might not mean anything. I need to check the vacuum switch. Anyone know what triggers the signal to open the secondary butterfly?

Coming from a 2.7RS powerband, my 3.6 feels a bit soft over 5,500rpm.

Any thoughts?

Tinker

P.S. Looks like Bill just might have posted an answer to the chip question.

Bill

This is reallu interesting (from the link you had):

Quote:

A short note on power at the wheels as compared to power at the flywheel of the engine. There is a lot of disagreement on which factor should be applied to convert power at the wheels to power at the flywheel; there is no fixed factor. We believe that the Bosch automotive handbook is a very credible source for an approximation method. Disregarding the tire deformation and -friction loss first, they state that the power loss through the transmission train is between 8 and 12% for longitudinally mounted engines, and between 5 and 9% for transverse mounted engines. This is without tire friction and deformation which has to be added and for whch Bosch has the following formula:FRo= f x m x g, where f is the friction coefficient (~0.015 for pneumatic car tires on pavement at 100 km/h, m is the vehicle mass in kg (we use only the mass on the driven wheels) and g is the gravitational acceleration 9.81 m/s2 ~ 10 m/s2. They also state that the increase of the rolling resistance f is directly proportional to the level of deformation, and inversely proportional to the radius of the tire. The coefficient will thus increase in response to greater loads, higher speeds and lower tire pressure. We normally test a car in the gear ratio closest to 1:1 in the gearbox, which works out to between 150 and 200 km/h at peak power on the dyno For the sake of getting an indictation let's take an average of 180 km/h. Power needed to overcome the rolling resistance of the tires on the roller on a 700 kg axle load is then P= (FRo x v)/3600, where P is kW, F in Newton, v in km/h. P at 180 km/h at 700 kg axle load would then be 5 kW. We use the high value of the Bosch transmission losses indication to calculate what we should get on the dyno if the car is functioning as it should.

{snip}

Another example: a Porsche Carrera 285 HP, deduct 12%, get 250.8, about 800 kg axle load, 220 km/h at peak power on the dyno; deduct 10, you come to 240 HP. Most put out around 235 HP on the Dyno. On the road this may be more because on the dyno the high pressure area at the air intake entry is not created.

My car was run on a DynaPak - a hub dyno - the wheels are removed and two dynos are connected to the hubs. This would remove the 10hp discussed above. The DynaPak corrects for all the stuff Wil talked about.

The dyno guy used 1.1x (9%) to get to flywheel. I'd happily believe 12% (free extra 8 hp :D). But the interesting part is adding 10% for a chassis dyno. It makes sense to my non-engineering brain.

So what does it give Moses? (231 + 10)/0.88 (or 0.91) - plus or minus 270hp?

I agree that the DynaPack is far and away the best way to dyno the chassis of a car. The DynaPAk is a truly elegant solution that avoids most of the issues presented by some other dynos. The DynaPak

measures load(torque) not inertia
does not need to account for tire related inconsistancies
takes into account gear ratio
measures rpm
measures AFR
is compact/portable
does not put undue stress at tie down points(there are none required)

Unfortunately most Dyno results are from Dyno Jets and their ilk. According to the article that I referenced the 285hp vram will measure ~240 on a Dynojet type which closely corresponds to the #s that I have seen on that type of dyno. The net drivetrain loss is ~15%

Another issue is that some dyno operators thow in a correction factor by hand, either to correct for environmental variables, gearing variables or to report flywheel #s. If they are honest and not trying to enhance their rep as tuners, I suppose this is OK, but the door is open to misrepresent the printed results (inflation).

As I said it appears to me that Marks car is down ~10hp and 10 ft-lb this is easily explained by non-functional vram and poor gas. In addition the power band is ~1k rpm lower that normal.

Tinker, the 3.6 while not as camy as the 2.7RS should still have a nice little kick at the top, I would suspect that possible the resonance chamber is not functioning. The secondary throttle(for the resonance system) is supposed to open @ 5500rpm but I don't have a shop manual so can't help w/ trouble shooting

Quote:

Originally posted by mikez
I am getting a RUF chip soon to compare with my Cyntex chip....wanna try one?

Hell yes! Let me know what you think.

I just finished a 400 mile drive where I pushed the car pretty well. 100 degree heat and the car pulls like a freight train. The oil temp doesn't budge. The motor doesn't labor under any conditions. Uphill acceleration is amazing.

Now I'm addicted. This could be big trouble.

Protomotive is the next, deadly step. ;)

Ingo is getting back into town today...."I" think he has a RUF varioram chip....I will look into it.