re - dyno hp vs flywheel hp figures

[gulf908]

Guys,

I have recently had my car at a dyno to sort a flat spot.
My mechanic has done an excellent job of sharpening the motors response by downsizing the jets and also some general sorting.
The dyno sheets now read 96 hp at the rear wheels,up substantially from when it first arrived.
Is there a chart giving a conversion to DIN hp at the flywheel ?
If not,what hp is an educated guess ?
The car is a standard US 914-6 (2 litre 911T motor)with a 2 outlet Danske sport muffler.

TIA
Dennis

[Chris Pomares]

I've been told it's in the 15% range. The engine was rated at 110 hp if I recall. Maybe the 15% number is close. I had a dark green one with a 2.2S in it back in the early 80's. Neat cars.
Chris

[Chuck Miller]

I agree with Chris,

I've learned approx. 15% as a basic rule of thumb for our cars....

Dynos, operators, climate, environment, computers all differ... but I've found that the relative ratio of 15% from flywheel to wheels stays pretty consistent...

I would love to hear if there is a different basic number to go by.......

[Mr9146]

I agree with Chris,

I've learned approx. 15% as a basic rule of thumb for our cars....

Dynos, operators, climate, environment, computers all differ... but I've found that the relative ratio of 15% from flywheel to wheels stays pretty consistent...

I would love to hear if there is a different basic number to go by.......

It all depends on the dyno used. There is no "standard" by which these things are judged or measured, and it's common practice to include the name of the dyno manufacturer when giving the results.

For example, my carbureted 2.5L twin plug made 180hp at the wheels on a Clayton dyno but it did 200.1hp at the wheels on a Dynojet with zero changes and after 15 track days and thousands of street miles. It would probably have read 500rwhp on a Mustang dyno.

I feel that calculated losses of 15% are a bit generous with our cars, and I usually use 10% as a nice, conservative estimate. Plus, it's easier to calculate.

[letsrollbabe]

It all depends on the dyno used. There is no "standard" by which these things are judged or measured, and it's common practice to include the name of the dyno manufacturer when giving the results.

For example, my carbureted 2.5L twin plug made 180hp at the wheels on a Clayton dyno but it did 200.1hp at the wheels on a Dynojet with zero changes and after 15 track days and thousands of street miles. It would probably have read 500rwhp on a Mustang dyno

I feel that calculated losses of 15% are a bit generous with our cars, and I usually use 10% as a nice, conservative estimate. Plus, it's easier to calculate.

Marco:

Do you divide by 0.90 or add 10%?....

[boba]

Gib, your just mean!

[Steve@Rennsport]

What Marco said!

Chassis dynos, all give different results so as such, they are only good for comparisons on the same day on the same dyno.

The same car will show different power figures on a Dynojet, Mustang, Dynapak, SuperFlow, Clayton, VT, Rototest & others. Some can be skewed by a smart operator, others not at all.

If you really want to know how much power your engine produces, pull it out of the car and install it on a good engine dyno.

[Mr9146]

Marco:

Do you divide by 0.90 or add 10%?....

That's cute, Gib.

Just for funsies, here's what it looks like when you dyno a car after you drove it across the country, and then to and from work for a year, and then to and from the racetrack for an entire season, and then for another season...you know, because I don't use a trailer.

https://www.facebook.com/video.php?v...type=2&theater

[edmayo]

Hmnnn,,,,methinks there is an inner message in that one,,,

[Mr9146]

Hmnnn,,,,methinks there is an inner message in that one,,,

Nah. Don't read too deeply.