I have searched my arse off and can't seem to find any info on the point of peak pressure for an N/A 2.2 L61 Eco. I would imagine it would be somewhat close to the rule of thumb 17* atdc looking at the shape of the combustion chamber but have no info to let me know for sure. Not sure i anyone has done the rather complex calculations to work this out before. I don't really want to go the increase timing to KR and then pull it back method. Don't have the time nor money to dyno tune it and not a fan of street tuning it. Also track tuning is out of the question this time of year up here. Not looking to get flamed just looking to see if anyone has any idea?
thanks
I don't have much to add here, however, I went with the add timing till KR method.
Problem is I'm at 32* of timing advance and I still don't have any knock at 13.5 AFR and 91octane.
Went to a dyno after tuning and only made 145whp
Peak horse power suffered pretty bad, dyno tunning for me in the spring....lol
FML
32* advance on top of the stock tables or total advance?
I think that would be total advance.
32* total isn't that much, for example at 6000rpm you have 100 revs per second, 1 rev taking 0.01 seconds. 94 octane would take roughly 0.002 seconds or 1/5 of a revolution which would be 72*. complete burn is at ppp so if it was 17* ATDC then 72 - 17= 55 BTDC. so total advance would = 55. But this is based on rough numbers, which is why i was wanting to know if anyone knew the PPP value.
^ these values are for WOT
DavefromEngland wrote:32* total isn't that much, for example at 6000rpm you have 100 revs per second, 1 rev taking 0.01 seconds. 94 octane would take roughly 0.002 seconds or 1/5 of a revolution which would be 72*. complete burn is at ppp so if it was 17* ATDC then 72 - 17= 55 BTDC. so total advance would = 55. But this is based on rough numbers, which is why i was wanting to know if anyone knew the PPP value.
How did you determine this? Burn rate is relative to both pressure and temperature. Both of these increase as the piston approaches TDC and as VE changes (and that's from the purely adiabatic property of air...and not including the contributions of increased temp and pressure from combustion). Unless you have a software program that can do the necessary calculations per RPM, I think you may be simplifying the chemistry/physics a little too much.
I have no signiture
I also forgot to mention that flame speed is dependent on the AFR as well, which adds another dimension to the problem.
I have no signiture
hence
roughly. all of those calculation were rough just to show that 32* total advance isn't much.
DavefromEngland wrote:32* total isn't that much, for example at 6000rpm you have 100 revs per second, 1 rev taking 0.01 seconds. 94 octane would take roughly 0.002 seconds or 1/5 of a revolution which would be 72*. complete burn is at ppp so if it was 17* ATDC then 72 - 17= 55 BTDC. so total advance would = 55. But this is based on rough numbers, which is why i was wanting to know if anyone knew the PPP value.
I know in the grand scheme of things its not alot, however, I have a feeling it is to much for a bolt ons.
Hopefully someone has an answer for you, send PJ a PM, if anyone would know it is him.
