26 replies to this topic

[matthew_leech]

See vid

https://m.youtube.co...h?v=ux6ihybv2-U

https://m.youtube.co...h?v=UQ2x-cg4NYM

Thanks

Matt

[matthew_leech]

Strange it feels it given its best by 5500rpm what was the CO reading under power?

It pulls very strong compared to the std 1088 I was used to. But the torque delivery feel tractor like rather than sporty.

Pass on CO reading I am afraid. I didn't think I was ever made aware of the reading in all honesty.

[Cooperman]

If the distributor advance is set for max at 5300, but the cam/head combination should be giving max power at, say, 6000 rpm, which may well be the case with the SW5 and 1.5:1 RR's, then it needs to be run to 6000+ rpm and a final adjustment of advance and mixture made at those revs. If it is 'running off the cam' at 5300 or thereabouts, there is an issue with the settings as it should pull right on through well over 6000 rpm. Use more revs.

It may be the further expected 5 bhp will then appear (or maybe not).

What ex. manifold and exhaust pipe do you have? Assuming it to be an LCB, is it a 1.75" diameter al the way from Y-piece to final exit. A larger pipe than that could be costing another 4 to 5 bhp.

[Spider]

Whats the head like if it was done by this unreliable chap ?  It could be anything to be honest , is the RR well regarded ?

 

Looking at that graph and in particular, the Torque Curve, well, I dunno how to put this or say it any nicer, but the head sux, and / or something else on the Inlet Tract. It really isn't doing the rest of the engine justice.

[Bubblebobble]

I suppose the bottom end really is a tried and tested recipe so to speak isnt it .its the head , cam and ignition that the power can be made or lost .

[Cooperman]

Any Mini engine with that spec should run to well over 6000 rpm and still have strong power.

The head is suspect, as is the alleged compression ratio. Once the head is done and it is set-up to run up to, say, 6500 rpm, it should 'find' the missing power and achieve the right torque curve. There is much to come from that engine once done properly.

[carbon]

Matt, what grade fuel were you using when it was run on RR?

[Cooperman]

Every rolling road graph I've seen has had a power curve which peaks and starts to 'run down the other side of the peak. This one is still rising when the run is ended at less than 5500 rpm. In itself that is unusual, especially so when combined with the unusual torque curve.

Why was the run not continued until the power was reducing after a clear peak figure? If the peak is not reached and the distributor swung at that figure of revs, the maximum power has not been reached.  If only going to about 5300 it would be best to remove the 1.5 rockers and revert to 1.3 as they will give better results on a lower revving engine.

All the 1275 engines from models like the Mk.1 Cooper 'S', MG Metro, 1990 - 1 Cooper 1275, etc, gave their maximum power at over 5600 rpm.

With the spec given, it is not surprising the max power seems a bit low - the revs were simply not high enough to see what the actual max might be, and then identify any apparent shortfall from there.  My suspicions are the compression ratio, the quality of the gas-flowing of the head, the distributor curve/advance setting and, possibly, the mixture for max power not being set at the high revs required for that power.

[matthew_leech]

Matt, what grade fuel were you using when it was run on RR?

it was Shell super unleaded.

[matthew_leech]

Every rolling road graph I've seen has had a power curve which peaks and starts to 'run down the other side of the peak. This one is still rising when the run is ended at less than 5500 rpm. In itself that is unusual, especially so when combined with the unusual torque curve.

Why was the run not continued until the power was reducing after a clear peak figure? If the peak is not reached and the distributor swung at that figure of revs, the maximum power has not been reached.  If only going to about 5300 it would be best to remove the 1.5 rockers and revert to 1.3 as they will give better results on a lower revving engine.

All the 1275 engines from models like the Mk.1 Cooper 'S', MG Metro, 1990 - 1 Cooper 1275, etc, gave their maximum power at over 5600 rpm.

With the spec given, it is not surprising the max power seems a bit low - the revs were simply not high enough to see what the actual max might be, and then identify any apparent shortfall from there.  My suspicions are the compression ratio, the quality of the gas-flowing of the head, the distributor curve/advance setting and, possibly, the mixture for max power not being set at the high revs required for that power.

Thank you very much for taking the time to read and reply to this thread.

 

I have learnt much.

 

I will swap the roller rockers for some 1.3:1 items and contact Aldon regarding a new dizzy.

 

Once these things have been changed I will go back to Pete Burgess' Rolling Road and get a new readout. With more revs :)

 

From whatever I find here I will have a more recent baseline to conduct any more trials and modification to.

 

I may be away for a couple of months before I get to doing all that but ill post up my findings.

 

Thanks everyone who posted.

 

Matt

[carbon]

Matt,

 

Would suggest that before getting a new distributor from Aldon it is worth getting a better idea of the advance curve requirements for your motor. You have a fairly short duration cam, and reasonably high CR, likely to need less advance at low rpm, more at high rpm as compared to a longer duration cam.

 

Starting with the distributor you have at moment, there should be a part number on it. This will allow you to find the centrifugal advance curve, max mechanical advance, and also vacuum advance.

 

Looking at your power/torque results the advance curve you have may be OK up to 3-4k rpm, but suspect ignition might be retarded after this point. On the RR Peter may have not been able to advance any further without hitting pre-ignition in low-mid range?

 

Do you know what the static ignition timing is set at? From this and the distributor spec you can work out what your current advance is at max rpm.

[KernowCooper]

I would suggest a Aldon Yellow with Vacuum advance the red is for Race application ONLY