joey bagadonuts

Dynamometer: Dynojet with dual rollers - 4th gear

"At the wheel" results

Max Power: 228.5 hp
Max Torque: 224.0 ft-lbs


I grilled the tech on appropriate conversion numbers to account for power loss from the flywheel to the wheels and he confirmed that 15% was correct for 911's BUT that AWD numbers should be adjusted 20%. I then asked if there were historical data or technical information from Dynojet to back this up and he said "no" but that his conversion factor was based on 996 C4 results obtained from the same machine, i.e. the 996 dyno figures reflected a 20% decrease from the Factory spec.

Results adjusted for 15% - 20% loss:

Max HP: 268.8 - 285.6 hp
Max Torque: 263.5 - 280 ft-lbs

I keep highlighting the torque numbers because they represent a quantum leap from the Factory-quoted 228 ft-lbs ... I guess eliminating half of your exhaust system will do that. Of course, I was pleased with the hp gains as well and feel the time and expense spent on various mods was worthwhile. And in case anyone's wondering, there was at least one car whose numbers were well off the Factory spec, so it wasn't all good news coming out this machine.

Questions?

johnfm

Good numbers. That g-pipe not only feels better, but the real dyno correlates to butt dyno. Good stuff Senor Bolso de churros!!

Cupcar#12

just wondering why your mix is Rich at 5.5 Rpm - ti spikes there where it should be stable and dropping at a steady rate - not enriching -
is this a stock DME chip - looks like a tuner chip

Cupcar#12

jsut looked at your sig...so it's a Giac Chip.
Next question.. then.. you are still running the stock Air Flow (barn door) which could be the reason for the spike. Hummm

joey bagadonuts

Gracias, Juan! Yes, it's nice to get confirmation that I haven't totally screwed things up. It gets even better. In Phil Raby's rolling road post, a lister by the name of LouZ was advised that 1.28 was the correct multiplier for a C4. That would equate to 292 hp for my car (which I would agree is VERY optimistic) but it does suggest that even the low-ball estimate of 269 hp is not unreasonable.

Good catch, Rob. So how could you tell I was running an aftermarket chip? I believe you're right about the barn door which opens at high revs causing the spike. The only intake change I made was to replace the entire airbox with an L-shaped tube which connects to a cone filter. This one, in fact:


Would the spike suggest there's further room for improvement? I'm a little confused, though. I was under the impression that the lower numbers actually reflected a richer mix, not the other way around. So when the flap opens, the spike would indicate a leaner Air Fuel Ratio. Does that make sense?

pzull

Joey,

Any idea what air temperature and barometric pressure was when you did the run?

rutz964C4

Hi Joey

Is that cone filter from EVO? did it made any difference (butt power) noise ?

I have one like that from EVO but didn´t have the time to install it yet right now the car is running with a more than drilled airbox with K&N.



ALEX

Christer

Joey

I have a question. What were your 'before' figures? Have you posted these elsewhere?

joey bagadonuts

Ah, the million dollar question! No, Christer, I don't know what my hp number was prior to all the mods. The only indication I had that I may have realized performance gains was provided by my G-Tech tests. I never clocked the current configuration since I somehow broke my G-Tech but I believe the addition of the cat bypass would have delivered 0-60 times around 5 flat. And while my dyno results represent strong performance in an absolute sense, I would have to agree that not knowing my starting point makes it impossible to determine exactly how much of a difference the chip/intake/exhaust mods made.

Alex, I believe the EVO cone filter IS a worthwhile bolt on (see the G-Tech link above). Noise-wise, I think it's actually a tad quieter than the modified airbox, probably because it's further away from the passenger compartment. I think we'd all be interested in your impression, as well, so please let us know how it goes. And don't forget to reset your chip.

Pzull, I don't have that information but will make a call. FWIW, it was a cool, 50F autumn day.

Cupcar#12

yes - but what is was refering to was the non-linear ness of the A/F graph the spike is right where the barn door has problems and would be expected but what is interesting is that at the start of your graph you are dropping to about 14:1 then flucuating 4.5K Rpm right where your engine comes on cam - normally you would enrich the mix and hold it there in a stead state. the engine is going to need more fuel to combat pinging at high RPM's - so normally this would be a steadly enriching mix. the Spike is leaning it out at 5.5K rpms - this is where the flap is fully open and is your torque peak.
On a dyno the air filter is not going to make much differenece - but the A/F meter will.
you might be able to tune that out of the RPM band with the chip - leaning it a little in the 5-6K rpm range. i would look at damping the osolations in the 4.2+ range - you might be leaving some power on the table there. the bottom end looks nice and steady

Slip of the tounge earlier i mean to say leaning the mix not enriching higher numbers denote leaner A/F mix - you want to run the engine as lean as possible with out pinging or starving it to get max power.

Christer

Joey

The other thing I wanted to mention was the torque. I am not sure you apply the losses to that or let me put it another way: when I dynoed before and after, my before figures were 207rwhp and 231lb ft, after figures were 221rwhp and 250lb ft. Now I don't know whether the torque was automatically calculated by the dyno or whether the torque should not have the losses etc applied to it. I could see the estimated fwhp, but the torque was just torque, no calculations.

In any case, I hope that you have made the gains that you think you have. It would be an amazing increase in torque. I think though that if I were you, I would go back to find out what the before figure would have been - otherwise the whole thing is a lottery and at worst I would be suing the chip manufacturer for misrepresentation.

tonytaylor

Must admit I was a bit suprised at the torque figures Joey had extrapolated. I have seen over 280ft/lbs from a 964 but there was over 300bhp.
cf my torque of 263ft/lbs but 298bhp at flywheel, 250+ at the wheels.

Joeys healthy bhp figures seem consistant with his mods and must be an improvement on stock

joey bagadonuts

Yes, Tony, I was just as surprised as anyone.

Thanks for the pointers and clarification, Rob.

Yes, Christer, you do adjust torque numbers with the same conversion factor. Your 231 "before" number appears to be a derived figure. For perspective, David K's RSA with headers, MAF and dyno-tuned chip registered a 227.7 max torque number; the adjusted result would be around 269 ft-lbs.

Cupcar#12

Personally - i believe Wheel figures and not adjusted numbers - there is too much varation in those.
Both of these graphs are very close in both HP & Torque uncorrected. Interesting...

RSAErick

Those numbers look great, Joe. You've got me itchin' for a cat- and secondary- bypass. I'll send my wish list to Santa....

Erick