Fun on the dyno with my Griffith...

[dnb]

Not too bad a result.  I'm a bit surprised by the antics at 4000 RPM.  The only thing that's different beween this and the 260 bhp result in the summer is my new isolated runner twin plenum.

[antonch]

The flat torque curve looks really good. Looks like you got some resonance at 4200 and then later on chokes the flow.

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Nicely done... quite what the 20 odd BHP jump is all about is a mistery, but it must feel nice in a lightweight car :)

[cliffb75]

53hp for just a different plenum is pretty impressive! I guess that shows how choked it was to start with.

That increase in torque looks too sharp to be airflow related, unless you've got an intake an exhaust system that just happen to hit their sweet spots at exactly the same speed, which is pretty unlikely, or you're running variable cam timing that we don't know about ;). What does your igniton map look like, as thats the most likely source of such a sudden change in torque?

[dnb]

Rover v8s tend to not flow air well at high RPM, so I'm not surprised by the torque falling off the way it does.  It was also very knock limited due to running on 95 RON fuel.  (I pulled 7 degrees from the original TVR timing)

The ignition timing ramps up almost linearly at a rate of approx 2 degrees per 1000 RPM at max load.  We checked very carefully for timing anomolies during the runs (15 in all) by adding and subtracting a couple of degrees, and the results were always the same.  I really need more than a morning playing, but that's all the time we had :(   I'll be able to resample the map to put a bit more resolution in there for next time.

[antonch]

Rover v8s tend to not flow air well at high RPM, so I'm not surprised by the torque falling off the way it does.  It was also very knock limited due to running on 95 RON fuel.  (I pulled 7 degrees from the original TVR timing)

The ignition timing ramps up almost linearly at a rate of approx 2 degrees per 1000 RPM at max load.  We checked very carefully for timing anomolies during the runs (15 in all) by adding and subtracting a couple of degrees, and the results were always the same.  I really need more than a morning playing, but that's all the time we had :(   I'll be able to resample the map to put a bit more resolution in there for next time.

I am not sure how much timing your engine likes but I just checked my basemap. I will be ramping up at about 4*/1000 rpm.

[cliffb75]

Rover v8s tend to not flow air well at high RPM, so I'm not surprised by the torque falling off the way it does.  It was also very knock limited due to running on 95 RON fuel.  (I pulled 7 degrees from the original TVR timing)

The ignition timing ramps up almost linearly at a rate of approx 2 degrees per 1000 RPM at max load.  We checked very carefully for timing anomolies during the runs (15 in all) by adding and subtracting a couple of degrees, and the results were always the same.  I really need more than a morning playing, but that's all the time we had :(   I'll be able to resample the map to put a bit more resolution in there for next time.

Not trying to teach you suck eggs or insult in any way, but just to confirm our understandings are the same, the 'max load line' is the true max load (MAP)achieved at each speed - i.e it is lower at low speed and higher at higher speed so that it moves diagonally (ish - it has a bulge) across the map. Therefore to check the ignition timing you are achieveing, you need to plot the ignition you actually measured during the run, rather than simply the top line of the map.

I assume that is what you meant?  :)

Unless of course you re using TPS as your load input, in which case I take it all back  ;D

Have you got a log from a 'good' run showing speed, load, lambda, ignition and EGT?

[dnb]

Here you go...  Remember that the sparks are really at 1/4 degree resolution, but the log rounds them to integers.

Note that it makes little difference about the top line as the MAP gets to atmospheric and simply stays there until the throttles are closed :D  But yes, I read the graph to get the numbers I posted earlier.

Lambda isn't worth plotting - you could do as well with a ruler at 0.9, and the EGT sensor broke on the second run.

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Those 'steps' look fairly equally spaced.

Maybe because its such and old engine it needs a rest as it climbs the steep power curve :P