Setting ignition on dyno
Turbo Mini Forums

Hy all, since my car is running now quite ok and i have few miles on it, i want to get it set up properly on a dyno.

Unfortunly people with experience in carburated turbo engines are rare as it comes. I have the standard metro distributor and wonder whats the way to go. I would have access to a dyno, but where to start?

What i heared was that you should advance the ignition till it starts pinking and then retard it a bit to be save. Is this a good way to set it up? I am not sure if i notice pinking, since i have no experience in hearing it and also run a straight cut gear.

Is there another way? as far i was reading in this forum the max. save advance differs widely from engine to engine.

best regards

Pinking is too late really and isn’t the ideal strategy, but you do need to still listen for it.

You need to tap in advance (starting retarded if you’re not sure) and add advance until the power plateaus.

The target is to make the power desired with the minimum advance possible. Once that power plateaus, don’t add more advance!

For a dizzy, you need to find the advance that the engine wants/needs for every 1000 rpm by swinging the dizzy, watching the output of the rollers, also listening for det, and then using a timing gun, figure out what advance the engine wants at that RPM. You can then find someone to tune the dizzy to give the exact advance for your engine needs...

Edited by TurboDave16V on 11th Oct, 2018.

Btw, we’ve a few guys here play on rolling roads quite frequently, and hopefully will also chime in - and hopefully correct anything I got wrong above!

Always avoid knock/detonation...simple.

Tune until MBT is reached....the no need to go further. But you may be prevented from reaching this by knock.

MBT seems to have different names...Minimum Best Timing ( to achieve max power/torque at any given load ) Or Mean Best Torque....same sort of end result really.

But tuning to detonation then pulling back, whilst very common is certainly not the way to tune on a dyno. ( Probably isnt the way anywhere, but many will do it and see good results...of course many will do it and blow shit up too lol )

And there should be minimal risk from knock/detonation whilst tuning if you are listening for it properly. Whether audibly or electrically.

High CR or Poor quality fuel setups are likely to be knock limited with timing etc. Something on fancy race fuels may well be able push advance beyond MBT without any knock/detonation so is still unhealthy for the engine and pointless doing so, power may even fall off again.

But I'd like to hope EVERY dyno operator would know the above basics regardless of the engine being tuned. Whether it's carb or injection doesnt make a bit of difference to the basics or dyno operation.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Pinking really only apply to part throttle cruise, if you try to do that on any decent boost level then your going to get detonation and somthing will break.

As dave says, add in a little boost at a time until power levels, you should also be listening for signs of det ideally with det cans

That last comment chimes with me because I think it is very difficult to detect detonation by ear and it will often be too late anyway.
Pick a dyno operator who understands A series and has det cans at least.

Think of MBT as the point at which the best torque is achieved for the least ignition advance. When you are far from MBT, 1 or 2 degrees change in advance usually sees a respectable increase in torque. When 1 or 2 degrees increase of advance results in little or no change in torque, you are at or near MBT.

You would add advance slowly from a safe value until you reach MBT and then remove some advance to see torque drop to verify. A safe tune would usually mean retarding at least 2 degrees from MBT with a sophisticated ignition timing system and maybe 5 degrees for a mechanical distributor.

Tuning for MBT on a forced induction engine might see it knock before you ever get to MBT. This means the engine is knock limited. It is always wise to retard at least 5 degrees from knock limit.

on a run of the mill normally aspirated engine you'll find MBT occurs way before knock, and as Dave said, it's the point at which very little increase in torque is seen when more advance is added. You can then actually see torque start to drop as advance is increased and still not experience knock. That cannot be said for forced induction, you will likely reach knock long before MBT.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Agreed.