Dyno Result

[Jacob]

At long last I have done my first Dyno - Oh boy []

The perfromance modificaions I have done so far:

SW chip
M&K 1 in 2 out muffler
Sport pre silencer
Drilled out air box (can't count for much!)

I Got 258.3 bhp at 6,739 rpm (126 mph)

Considering the above figure, I would have imagined a higher torque figure - only 207.6 lbft at 6,342 rpm.

The thing that really strikes me with this reading is just how late the power is coming on

 

[audicdl]

Did you ever get it checked before any of the mods Jacob, to know what you've gained?
Chris

 

[bruceb]

That engine must be great to drive with that torque curve, the peak torque must be over 1000rpm higher than stock

 

[Mike58]

my modded 3.2 showed a very similar high end gain, the engine really screams to the red line.
After changing up at nearly 7000 rpm you don't need to worry about torque as you are soon in the real power band at 5000.
Great fun these modded engines
If you want to buy my mods...... http://www.porscheclubgbforum.com/tm.asp?m=191941

Mike

 

[Richard Savage]

Jacob

I would be interested to know how your engine modifications have affected your insurance premium, since clearly the engine is no longer standard, thereby making the original insurance declaration void, or have you simply ignored the fact!

R.

 

[Jacob]

ORIGINAL: audicdl

Did you ever get it checked before any of the mods Jacob, to know what you've gained?
Chris

Should have done really, but this is the first Dyno I have done

 

[Jacob]

ORIGINAL: Richard Savage

Jacob

I would be interested to know how your engine modifications have affected your insurance premium, since clearly the engine is no longer standard, thereby making the original insurance declaration void, or have you simply ignored the fact!

R.

This has never been a problem in the past. I am currently insured with classicline. All they ask for is that I can provide the cost of any modifications I have made, if requested. They were not interested in any performance gains whatsoever

 

[nathan 1981 930 G50]

Hi Jacob.


Did you have the AFR checked throughout the rev range ?

It would seem possible that you are running too rich or too lean in the mid range and therefore losing power and torque. Maybe the ignition timing is not optimized in the mid range.

It is possible you don't have stock cams, the heads have been modded or the cam timed different to stock.


As for the insurance, that is great. I can never seem to get a quote for a BHP modified car unless it is garaged. My 930 with extra 100BHP had an additional 25% load on the premium.

Do you also have to garage the car ? Maybe you are just paying so much anyway, how much do pay ?

 

[Jacob]

unfortunatley, I was the only car not to get an AFR. I have no idea why they left me out []

I only pay £300 for the insurance, limited to 5k miles. (9 points and no accidents) The car is garaged every night. I almost couldn't believe when I got the quote

 

[Guest]

There is often not enough airflow over the probe to get good AFRs with the twin out muffler apparently.

Questions:

1. What kind of dyno?
2. I presume this is flywheel hp. Is it corrected for conditions? Temp, atmospheric pressure etc.
3. What is the drivettrain loss they used to go from rear wheel to flywheel hp?
4. How did you riase the peak hp rpm without changing anything internal on the engine.
5. I know you didn't dyno before mods but what have other 911s dynoed at on this dyno?

I don't want to be a spoilsport, but don't you think this dyno information kind of asks more questions than it answers? I mean, I have never seen a std 3.2 hold on to its peak hp so high in the rev range - they are normally spent by 6200rpm. The mods you have done should not dramatically change the shape of the curves like this.

RB

 

[Jacob]

answers:

1. Maha dynometer
2. It is a flywheel reading and corrected for biometric pressure and temp.
3. The drivetrain loss is calculated from the car on the run out
4. SW? (I opted for the 98 RON type 2 chip early into development)
5. Mostly 993's and 996's running at stock bhp levels

I agree, this all looks a little good to be true and a dyno is only really good for before and after comparisons. FWIW the technician claims his readings are always conservative and this was backed up by the dyno day organiser who have been using the dyno for a few years now.

I guess that I really ought to get a 'second' opinion from a better known dynometer (I think ninemiester in warrington are probably the best up north) - but for now..... 258.3

 

[Guest]

ORIGINAL: Jacob

answers:

4. SW? (I opted for the 98 RON type 2 chip early into development)



I guess that I really ought to get a 'second' opinion from a better known dynometer (I think ninemiester in warrington are probably the best up north) - but for now..... 258.3

Unfortunately it just doesn't work like this. To increase the peak power rpm and hp like your dyno curve shows, you'll need to increase your airflow. Basically the engine is at full-song at the peak torque engine speed. Above that the cylinders get incrementally less and less charge due to the mixture not being able to keep up with the engine speed.

To change the airflow you're looking at changing either cams or to a lesser degree the porting. The best results are by changing both at the same time to support your targetted curve.

Your curves look more like 993SS cams than a stock 3.2 although the torque curve is peakier than it should be.

Fair play to you though if the 993s and 996s were dynoing close to stock power. The 9M dyno also seems to produce some pretty amazing numbers so I wouldn't take that as gospel either. I am not saying your hp is BS (though its very toppish[]) its just the shape of the curves that looks wrong.

 

[Jacob]

The truth of the matter is that I would be pleased with anything circa 240 with the mods I have carried out. To get these figures does indicate that something isn't right. I'm pretty sure I haven't had an engine rebuild, never mind 993SS cams[]

I sent the dyno over to SW to have a look at, his immediate suggestion is that the dyno looks to give about 500 rpm to much. Looking in to it further he came back with this response:

Hi Jacob, The appears to be a respected dyno in Germany, but I have very little data collected from such dynos to provide a decent comparison. My associate in Germany has provided me several dyno runs from his 3.2 on a Maha dyno, but the numbers are nowhere as high as yours - his are about 225 corrected to the engine. I do notice that his curve peaks out also at 6700 rpm, so I think there is some type of discreptancy on the Maha dynos vs rpm. His car is just an 89 3.2 U.S. spec car. Regards,Steve

 

[Guest]

Well good illustration of the perils of "dyno racing". Still, its all good fun and if that was my dyno number, I would stick to it and proclaim it gospel!

You do track days right? How quick do you reckon it is compared to other cars on the track. That's a more real world benchmark - though entry speed onto a straight is ultra-critical.

 

[Jacob]

Really difficult to comment - I think that driver experience on the track accounts for a lot, of which I have little!

On a track day last year a fellow 3.2 owner commented on how much quicker I was on the main straight, but as you say entry speed on to straights is very critical.
In other situations where I have been driving alongside 964's I have definitely held my own.