Using BMEP to calculate TA ?

[Wayne Miller]

Does anyone know how to calculate TA from BMEP figures ?
Or know of any sites that could help me discover the formula?

Cheers Wayne

[Wayne Miller]

i'm not sure about this or what assumptions are made but try these: I didn't add these to the lambretta-images timing calculators because as i say, I'm unsure where the formula came from or if its correct.

BMEP(bar) + 9.66 / 2400 = TA (transfers for higher primary comp)

BMEP(bar) - 0.128 / 587 = TA (transfers for lower primary comp)

Cheers for that mate. I already have those figures, there quotes from Blair. I was just writing a reply to you say that RPM was missing from the equasion and that you obvioulsy need it as TA changes with RPM. Then I had a Eureka moment and realised that RPM was already there in the BMEP figure!!!

The only problem is, Im not calculating my BMEP in bar. I need to find the calc for this now.

[Wayne Miller]

PSI/14.503795 works it out roughly

cheers mate

[Wayne Miller]

i'm not sure about this or what assumptions are made but try these: I didn't add these to the lambretta-images timing calculators because as i say, I'm unsure where the formula came from or if its correct.

BMEP(bar) + 9.66 / 2400 = TA (transfers for higher primary comp)

BMEP(bar) - 0.128 / 587 = TA (transfers for lower primary comp)

Heres all of the rest mate, BMEP are all in bar

INLET
((BMEP+1.528)/774)

TRANS UPPERBAND
((BMEP+9.66)/2400)

TRANS LOWERBAND
((BMEP-0.128)/587)

EXHAUST
((BMEP+5.975)/1050)

BLOW DOWN
((BMEP-1.75)/8187)

all of the figures can be confirmed in blairs book page 432. He writes them in a more complicated/intelligent manner but thats how to do it above in laymans terms

Thanks for your replies mate, helped get me thinking on the right lines again.

Im off to find the answers to the next puzzle