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Thread: Dyno readings

  1. #1
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    Dyno readings

    Gentlemen:

    I just put a new clutch and a set of rebuilt webers on my 67 S. The 40IDS3C's have the adjustable cam lever bar and were tuned on the dyno. The motor is quite fresh (I'm afraid that I can't be more specific - wish I could) the fuel pump is new and it appears, especially after all this work, to be running really strongly. It is also using an MSD box and coil.

    What should I read as a power rating in either HP or kW at the rear wheels during a dyno test? What kind of losses are expected in the driveline? How can one work back to the flywheel rating? The factory's 160 HP (DIN) rating is flywheel power isn't it? What is a typical rear wheel power rating?

    I was told that I am putting down 62HP to the pavement and that this translates to ~130HP at the flywheel. Further, I was told that the crappy fuel these day full of that MMT crapola could account for the 30HP difference between the factory rating and what was measured - is this true? Anyone else got some results to share?

    Thanks fellas.

    A67911S

  2. #2
    What kind of dyno was this? 62 hp to the wheels is almost unbelievably low. And it's hard to understand the calculation based on more than 50% drivetrain loss.

    More information might explain all this.

  3. #3
    Goldmember ttweed's Avatar
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    Re: Dyno readings

    Originally posted by A67911S
    I was told that I am putting down 62HP to the pavement and that this translates to ~130HP at the flywheel. Further, I was told that the crappy fuel these day full of that MMT crapola could account for the 30HP difference between the factory rating and what was measured - is this true? Anyone else got some results to share?
    Something is seriously wrong with your figures. I have had my '67S on the dyno and it is set up exactly like yours. It showed 130HP (SAE) at the rear wheels. Driveline losses can be anywhere from 10-20%, depending on what type of car. I figure mine is pretty close to the 160 DIN the factory advertised, considering it has ~70K miles on it since last rebuilt.

    TT
    Tom Tweed
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  4. #4
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    As I suspected...

    I thought those figures were out to lunch. The car is running fantastically now, as it should after spending close to $10,000 CDN on all the work I've done lately.

    My brother drives a BMW 2002Tii and my beauty definitely has more guts than his ride. The FI'd Tii is supposed to be rated at 150HP DIN I'm thinking that maybe I'll go back to the shop and watch him dyno the car. I just want a baseline to work from in the future.

    Anyone been able to squeeze more than 160 out of a 67 S?

    thanks;

    A67911S

  5. #5
    Slow In...fast Out RSupdate's Avatar
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    I would have to go with Jack on this....

    That' unbelieveably low h.p. reading at the rear wheels.

    I've understood the common "rule of thumb" for h.p. loss as this:

    manual trans = 15-17% loss

    auto trans = 20-23%

    Now once again, these are general "rule of thumb" averages, and if that was my car I would be inclined to use the 15% loss and conclude I was probably getting about 110 h.p. to the ground. But that's just me
    Johnny Riz
    73E euro 3.2 w. a few goodies
    Rgrp 152
    S Reg 335

  6. #6
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    Alrighty then...

    Using those numbers (for a manual of course), and working backwards from the factory 160HP, then at 15% loss the reading should be ~136HP and at 17% should be ~132.8HP, (o.k., o.k., we'll call it 133HP).

    Well I was just out puttering (read leadfootin') about town and WOW is she fun to drive. She gets squirrely in the corners just like she is supposed to, and backs it all up with a mechanical symphony! I guess I'll just have to find someone around here with a regular 2.0 to trade rides with and see how she measures up.

    Thanks again gents;

    A67911S

  7. #7
    Slow In...fast Out RSupdate's Avatar
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    Re: Alrighty then...

    Originally posted by A67911S
    Using those numbers (for a manual of course), and working backwards from the factory 160HP, then at 15% loss the reading should be ~136HP and at 17% should be ~132.8HP, (o.k., o.k., we'll call it 133HP).


    You are correct based on what I understand.

    Also, my appologies for using the 130 h.p. in my example, I intended on using 160 h.p. sorry.
    Johnny Riz
    73E euro 3.2 w. a few goodies
    Rgrp 152
    S Reg 335

  8. #8
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    No appologies please...

    No appologies necessary amigo. I got the gist. I just wanted to be sure and clarify (if required) for others reading the list.

    Happy motoring.

    A67911S

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