wtdoom

How are so many 964s making over 300 hp ? With my pipe back on im just about 270 .
Can you tell me about your engines please ?
Interested in the routes people have taken , thanks .

Cheeksyboy

Your friends Colin and Mark put my engine together. It's still 3.6 but runs on motec and has modified heads and cams.

wtdoom

sounds fantastic , how much Power ?

boxsey911

Mine's standard albeit it rebuilt recently so just quote Porsche's own figure of 250. It always feels like they're all still in there to me.

bigunit_271078

I think mine has 251 horses powering it.........

wtdoom

they grow horses big in stuttgart though

raoul

Re sealed engine, cat bypass, cup pipe, and re map by Wayne Schofield to 297bhp...apparently. Have the print out and pre map was around 278bhp. Having had a rebuilt 964 before it seems quicker but also seems remarkably high output wise for a fairly standard engine.

Some well known tuners have developed an industry reputation for massaging their figures that then can't be replicated when re measured elsewhere.

KaiB

Some well known tuners have developed an industry reputation for massaging their figures that then can't be replicated when re measured elsewhere.

To paraphrase a line from a popular US TV show....

"ya think"....

or perhaps from another...

"DOH!"

trophy

HP measures are a relative thing, when used to compare before and after modifications, on the same dyno in the same conditions, they are a valuable tool.

Comparing cars outputs by posting different dyno sheets from different dyno's under different conditions is a waste of bandwidth.

Now if you can get 20 cars together and put them on the same dyno on the same day under the same conditions then a relevant comparison could be gleened.

wtdoom

Agreed .

I have head work ( oh er misses ) , roock cams and a rebuild a few thousand miles ago . around 270 hp . Interested to run against the big power 64's .
I presume many are 3.8 l ?

wtdoom

track performance dyno is the most reliable dyno

Porsche964FP

Yup I'm 3.8 but the higher capacity contributes to torque. Otherwise cams, induction, exhaust, Motec raise my HP.

NineMeister

Putting it as simply as I can, there are far too many variables to be able to freely compare performance results from different dynamometers. To name but a few, the dyno design, installation, roller inertia, the operator, the weather conditions, air supply (& removal), the wheels, the tyres, the transmission and the flywheel all influence the results that you will see when trying to "replicate the result elsewhere" in your terms. This is a fact.

Interestingly you mention Wayne Schofield (of Chipwizards) who is a long standing associate of mine. Wayne owns a Bosch FLA203 two roller inertia dyno - the same Bosch who designed and made the standard engine management system in all 964 & 993s. I own an identical FLA203 dyno which was upgraded with a Dynostar control system and software package around 8 years ago, the key advantage being that I can store an infinite number of dyno runs to compare results and also run the dyno in a compound inertia loaded mode with the car accelerating the mass of the rollers with additional brake load, thus slowing down the acceleration rate to simulate different gears. Historically the results from the 9m & Chipwizards dyno corelate within 1% of each other.

At 9m we often rent out the dyno to other tuners for testing and mapping purposes and one of the associates who uses our facilities is a leading Honda specialist who regularly achieves 150hp/litre from his naturally aspirated honda race engine conversions. His cars are fast and reliable, often beating much larger engined & turbocharged vehicles with huge power outputs, the resuls reflecting on his exceptional technical abilities. His analysis of the 9m dyno is that it measures his engines within 2% of the same car on a calibrated £500k hub dyno and engine dyno. For him the most important factor is the repeatability of the system to produce quantifyable measurements between runs and he has found that the 9m dyno is within 0.5% run to run. For a tuner this is critical if meaningful improvements from updates and changes are to be measured accurately.

Which leads me on to the point. Dynos are just a comparitive tool. Most dynos measure tractive power by calculating the acceleration of a fixed rotational mass (the rollers), calculate the wheel/transmission power losses by measuring the slow down rate of the rollers before finally calcuating engine output by adding the rolling losses to the measured wheel HP. Some then correct the figure to DIN or SAE standards by multiplying the result with a correction factor based on measured atmospheric conditions (air temp, pressure, humidity). Hence if you want a meaningful comparison between changes made to your engine, test the car on the same dyno before and after in the same conditions with the same operator and you will be able to reliably compare the results.


I have known Wayne for probably 15 years or more. At no time have I ever known him to fudge or alter results from before/after tests on his own dyno. Furthermore Wayne has enough experience to ensure that he repeat tests 911 engines at the same cylinder head temperatures to achieve meaningful results. I would say that if Wayne has measured your engine at 278hp before and 297hp afterwards, the engine will definitely make 7% more power after his remap. If you stubbornly assume that your engine actually started with 250hp before then it will still make 250 x 107% = 267hp afterwards, but who cares? The point of the tuning exercise is the 7% which you have accurately measured.

Finally, a little piece of history. Wayne's dyno used to belong to Peter over at ABG Motorsport in Runcorn. I used that dyno at Peter's place for 20 years before buying my own set up. So did Steve Holgate of Exclusively Nine, Phil Hindley of Tech9 along with many other tuners. Peter always did the driving of the car under test on his dyno and strapped the cars down in the same manner. His independently quoted the results that others achieved with the 964 and 964RS engines, in general the best he had seen for the RS was occasionally 305-308hp. The first ever 9m 964RS Motec upgrade was tested on the ABG dyno. It made 325hp when tested by Peter; in fact I still have the original paper dyno graph from that test in 2002 should anyone want to see it.

race911

^^^^ What a nice recap on how things progress, and inter-relate.

As far as the comment above about the biggest squirrel-power dyno numbers, I'll point you guys in the UK in the direction of Peterborough for the Kings Of Outlandish Claims (see avatar if you need a hint).

raoul

Thanks for that. I wasn't implying Waynes figures were wrong at all. I have used Wayne several times and regard him as being at the very top of his field. I recommend him to anyone who wants a chip upgrade and wants to get their cars running "right".

The second paragraph was an aside, not connected to Wayne at all.

What i should have said was "engine builders" not tuners.