Dyno Results - Gordo's 3.2L

[Gordo2]

I dyno'd my rebuilt, warmed up 3.2L last weekend. I"m posting part of the results, leaving out the HP #'s for speculation... Will update with the full graph next weekend.

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A bit of background on the rebuild

I built the engine with the intent to optimize it for street driving performance. Modifications were oriented toward improving lower RPM torque.

Rebuilt 3.2L Engine Specs include:
Dougherty Racing GT2-102 cams (Dougherty Racing Cams)
JE 9.5:1 pistons (measured CR came to 9.3:1)
Electromotive XDi Ignition (Initial @ 12º, 3000 RPM @ 20º, Rev limit @ ~ 6,500RPM)
SSI exchangers with Dansk 2-1 muffler
Stock 3.2L heads - reconditioned
ARP rod bolts and head studs

46mm PMO Carb Specs
36mm venturi
F16 emulsion tubes
140 main jets
150 main air correction jets
55 idle jets
140 idle air correction jets

Link to the rebuild: Gordo's 3.2L Engine Rebuild - Ready to Reassemble

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Why Did I Dyno?

My primary interests dyno'ing were to ensure my PMO carbs are configured/optimized across the entire RPM range and to optimize my Xdi ignition settings.

Secondarily interested in seeing what kind of torque and HP results my component selections produced. I realize that the #'s produced by dynos are subject to a wide range of variables - as such I was primarily interested how my mods influenced in the curves.

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The Dyno Results (In Part)

Just for fun, I've erased the HP results from the dyno graph:




For reference - here's a link to a wide variety of Porsche 911 dyno pulls: 911Chips - Porsche Dyno Runs

Note how most Porsche 3.0L and 3.2L engines produce max torque in the 5,000 RPM range, and normally produce ~ 150 to 175 ft-lbs from 3-4.5K RPM.

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Driving Performance / Impressions

I've driven the vehicle with the rebuild ~5,000 miles or so and have been very happy with the outcome and performance. It's very strong down low - dropping the pedal in 3rd or 4th gear at 3k RPM plants you in the seat through redline...

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HP Speculations...

Any guesses on where the HP #'s came in? I would also be interested in hearing perspectives on the relative importance that HP has upon street driving performance (hint)...

Gordo

[mreid]

235 at the wheels.

[Ferrino]

Originally Posted by mreid

235 at the wheels.

The graph maxes out at 210, so I'll go with 202 wheel HP.

[Steve W]

200 @ 6100

[LakeCleElum]

My 3.2 with Cams, early exhaust and high compression Max Moritz kit did 209 at rear wheels....Timing more agreesive at 29 degrees for 6K.....I think Steve is pretty close...

[pampadori]

IIRC, HP = Torque x RPM ÷ 5252. So around 201hp around 6000 rpm?

[LJ851]

I bet those SSIs are holding back a fair bit of top end HP.

It would be interesting to dyno my car and compare to yours. Its a bone stock 3.2 with SSIs, 2 in 1 out Monty and 46mm PMOs.

[jeffbottman]

My recent dyno run yielded 211 RWHP:

Stock 3.2 except Steve Wong chip and M&K free flow exhaust system.

[chris_seven]

As Horsepower cannot be directly measured but only calculated from the torque figures measured by the dyno the conversion is straightforward.



If the torque figures are derived from the wheels and no 'roll down' has been carried out then the curve will simply be as shown above.

If the figures at the wheels is converted to Engine horsepower then the software will use a 'Bulgarian Constant' to multiply the horsepower calculated from the measured torque.

There are several errors that may be present and the magnitude of the factor used to ESTIMATE flywheel horsepower is the subject of significant debate and why it is almost impossible to genuinely compare results from one manufacturer's chassis dyno to another.

Trying to determine the horsepower that a chassis dyno will display from the measured torque curve is just guesswork without access to all of the factors used in calculation and correction.

An accelerometer App on a mobile 'phone is probably almost as good.

If the Chassis Dyno is an inertia type further errors can creep in as torque is calculated form roller acceleration and another Bulgarian Constant may have been introduced.

Compensation for air temperature and barometric pressure may also be included.

I would expect that even a well maintained and carefully operated Chassis Dyno would have a minimum uncertainty of 5% of it's maximum measuring capability and this would increase significantly when used at 40-50% of total capacity or lower.

As most shops are 'selling horsepower' the factors used are quite often a bit of a stretch as good figures can make for happy customers.

Good quality Engine Dyno's such as Kahn Waterbrakes will generally be much more accurate but an uncertainty of 3% would still be typical.

The best 'motoring Dyno's' used by F1 engine manufacturers are around 1% as they use very high quality non-contact rotating torquemeters that can be calibrated to around 0.1%.

[cmonref]

xx

[MDamen]

Yeah, what Chris said. HP is calculated from torque, not measured.

[Gordo2]

Oops, not much room for speculation with the info I provided (for you guys with your fancy math, formula's and ability to focus on the obvious from my graphs ).



The point I was trying to convey was that engine modifications should be focused toward achieving the greatest influence on power within the RPM range that you typically drive.

I selected modifications that resulted in an engine that produces power where I most often need it - in the 3 to 5k RPM range. I'm in the engine's power band when I'm cruising in 3rd or 4th gear - quickly accelerating up from 3k RPM (to pass, or accelerate in and around traffic) through 5k RPM.

Meanwhile 200 RWHP isn't all that impressive - but for the most part, it's irrelevant with respect to my typical driving profile.

Just a few thoughts toward engine builds and keeping a focus toward the objectives of your modifications (and hard earned money)...

Thanks for the feedback folks - great gouge and clarity.

Gordo

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BTW

I started with B&B 1 3/4" headers and PMO's with 38mm vent's and drove it for over a year with these. I swapped in the SSI's/Dansk and 36mm vents (and tuned...) to find the engine felt much stronger in my target RPM range. I did't dyno before I swapped - next year, I may swap them back in and dyno - just out of curiosity.

I doubt swapping the B&B's and 38 vents will result in significant bump in HP, but believe they may reduce my lower RPM torque. I also believe my torque curve is primarily influenced by my cam choice...

Quick note on the Electromotive Xdi settings on the dyno - we found that 33° total advance produced the best power: the curve dropped if we adjusted lower or higher...

[carrerarsr65]

where did you have you dials set xdi

[chris_seven]

The torque versus horsepower debate is one of those areas of engine performance that will never be resolved.

Is simple acceleration terms horsepower will always win the performance argument over torque providing the vehicle is optimally geared.

This is why the pervious generation of F1 engines all have much better horsepower figures than torque figures.

The old V10 3.0 litre engines produced around 800BHP at 19000 rpm but a peak torque of only 300Nm.

Quite different characteristics to steam engines which can produce huge amounts of torque at zero rpm.

The clue to a cars drivability is the gap between peak torque and peak power - the larger the gap the better from a drivability perspective.

Another way of looking at this is to consider and calculate 'tractive effort' which takes gearing into account.

The problem with analysing torque alone is that it doesn't offer any useful information with regard to performance due the influence of gearing.

Also consider that below 5252rpm the torque figure will always be greater than the horsepower and above 5252rpm the horsepower will always be greater than the torque.

[MDamen]

I have not heard of looking at the difference between peak torque and peak hp to get an idea of drivability. That makes sense. A low torque peak gives you acceleration and pulling power. A high rpm hp peak means the torque is not dropping off quickly. A wide gap between torque and hp peaks would imply a relatively flat torque curve, which would promote drivability.

[Gordo2]

Originally Posted by carrerarsr65

where did you have you dials set xdi

I ended up with 12° initial and 21° at 3k RPM for a total of 33°.

I may continue to play with my initial setting, but keep my total advance at 33°.j

Keep in mind - every engine is different; this is what worked for mine.

Gordo

[Maxhouse97]

Gordo - if you want a comparison, see my dyno results below. The engine is a stock US 3.2 w/ webcam 20/21s and sport muffler + Steve Wong chip.

You certainly blow me away on torque below 4500 rpm (which was your objective). But then it seems like your falls off and mine stays steady. Seems like this may be from the SSIs? It's interesting because I have a nearby thread where I say I want more torque and advocate for moving the SSIs. But after seeing your dyno results I'm not so sure. My 220 rwhp is nothing to sneeze at (and this was before moving from a 91 octane chip to a customized 93 octane chip). I want more torque but not at the expense of that much power.

But I bet your car is more fun to drive!

[Gordo2]

Originally Posted by Maxhouse97

Gordo - if you want a comparison, see my dyno results below. The engine is a stock US 3.2 w/ webcam 20/21s and sport muffler + Steve Wong chip.

... But then it seems like your falls off and mine stays steady. Seems like this may be from the SSIs? ...I want more torque but not at the expense of that much power.

Thanks Max,

I think my torque curve / profile is primarily influenced by my cam, but the exhaust surely had some amount of influence.

I originally had B&B 1.75" headers on the engine before I swapped to the SSI's w/Dansk. It ran strong, but felt stronger with the SSI's. I didn't notice a drop in upper RPM performance, but there probably was some loss of HP. I think the HP difference would be hard to notice unless you drive in the 5k + RPM range regularly (i.e. track) - less noticeable how I drive - quick 3rd to 4th gear launches from ~3k to 6.5k RPM and quickly back to a regular 3K cruise (out of concern I'll find myself followed closely by the guys with blue lights if I remain above 6k through the gears for more than a few moments...). I spent considerable $$ to build / influence the engine this way, but performance impact from a regular driving / seat of the pants standpoint puts a smile on my face every time I get into the pedal...

I didn't dyno it with the B&B's, but may swap them back in next year for a dyno run to get a better / measured feel for how they influence performance.

Thanks for the chart - good reference.

Looks like you achieved some tangible (and measurable) performance improvements from your upgrades. Interested in your take on how the mods influenced performance from a seat of the pants perspective - were the results significantly noticeable?

Reason I'm asking - my brother Cabmando has been considering upgrades similar to yours.

All good fun. Thanks again,

Gordo

[scarceller]

What you managed to do is move the entire torque curve 500RPMs lower. I think you did that on purpose? Is that correct?

I compared your torque curve to my Euro 3.2 and it looks like yours is shifted 500RPMs lower from 4000-5500RPM while in my engine it sits at 4500-6000RPMs.

[scarceller]

Here's a run from my 3.2L, look at the red run.


Engine Specs:
Euro 3.2L
WebCam 20/21
Extrude Honed, flowed and polished intake
SSIs with 2in2out M&K muffler