Reading / Interpreting Dyno Charts

Seikoking

Well-Known Forum User
I have recently had a few little jobs completed on my 260Z and part of the work was little rolling road session.

I am interested to know how to “read” the dyno charts and maybe what the charts tell us. I am not looking to chase BHP necessarily as the car will never see a track, but it would be interesting to hear thoughts about what could be done next?

It’s an L28 N42 block and N42 head running triple Weber 40s. I don’t know what work has been done prior to my ownership (if any). Not sure on the jetting set up of the carbs from memory but might be able to dig up the info.

B1BF89CA-6C11-415A-B68C-59912C355035.png
 

Rob Gaskin

Treasurer
Staff member
Site Administrator
Looks great to me - very drivable.

Seems like they sorted the low rev issue.

You want the 'curves' to be to be smooth (not like a mountain range).
 
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jonbills

Membership Secretary
Site Administrator
Torque and power peaks are in pretty normal places, so a relatively standard cam setup I'd think but a decent chunk more than stock.
Normally you get AFR or Lambda plot with it which would help confirm it's doing the best it can.
Assuming it's fuelling right and decent ignition timing then its done - time to start thinking about what you'd want from the next engine build :)
 

Rob Gaskin

Treasurer
Staff member
Site Administrator
I can't tell anything without the air/fuel graph. looks linear.

looks like they stopped revving at 5250rpm? why was thatt?

I remember when I had my old car on a rolling road (in a closed garage! with exhaust-vent) they stopped at about 5,500. The noise was incredible and it makes you realise what mechanical forces are at work - we are usually isolated from that.

Also is there any point considering on the graph above the max's have been reached and the driver probably wouldn't go much higher anyway?
 
I remember when I had my old car on a rolling road (in a closed garage! with exhaust-vent) they stopped at about 5,500. The noise was incredible and it makes you realise what mechanical forces are at work - we are usually isolated from that.

Also is there any point considering on the graph above the max's have been reached and the driver probably wouldn't go much higher anyway?

yes there is, if it had the air/fuel on there you can see what might be causing the drop off etc.
 

Seikoking

Well-Known Forum User
I remember when I had my old car on a rolling road (in a closed garage! with exhaust-vent) they stopped at about 5,500. The noise was incredible and it makes you realise what mechanical forces are at work - we are usually isolated from that.

Also is there any point considering on the graph above the max's have been reached and the driver probably wouldn't go much higher anyway?

That was the reasoning the tester gave also, but sounds like there could more to be learnt with AFR data too.

I am planning to install a cold air box (members group type) as the next job. At the moment nothing other than foam filters on the trumpets which I understand will help. It was a recommendation from Ric at the dyno.
 
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