Cam Timing Discussions -
Turbo Mini Forums

Looking for input here.


This image is for a 2.5 dtec engine that I'll be putting in my daily driver focus. This is a plot I pulled today of the cams as they are set up in this 16K mile donor engine.

The donor has VCT, which explains why the inlet cam (orange) is so far retarded; obviously that needs advancing to a better zone that'll work for a non VCT engine.

I still feel like the exhaust cam (blue) needs a tweak - it's clearly pushing little overlap, but another thought is getting another inlet cam and running in the exhaust; but that maybe is adding too much overlap for a daily? I can get the cams for pennies - the engines were made in such large numbers, and are long lasting, they are almost giving them away...

Anyone use one of those "desktop dyno" programs that would point to optimal timing?

Again, this is a daily driver. it's not turbocharged, or a screamer. it's a plodder - but I'd like it to be optimal.... I don't have any emissions testing over here, but (again) being my daily plodder, economy and torque is key, while still being able to pull hard up to redline when I am on the motorway.

Cheers!

Edited by TurboDave16V on 14th Jun, 2020.

looks like a good cheap experiment would be to pop in another inlet cam on the exhaust ,give it a softish lsa , say 110, and pop them in 4 d advanced.


good thread https://forum.miata.net/vb/showthread.php?t=636604

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Alrighty then,

I've played with the plots, and the inlet cam in the exhaust looks pretty good.

I've moved the plots to the numbers Robert suggested, and the overlap (road car remember) looks very minimal (disclaimer - these plots were taken at the bucket so lash is already included (0.15 to 0.2mm lash is what I'm seeing).

Thoughts on would be the effect of opening the LCA up a little more, to 112 degrees?

there are so many variables , , best to bung it together with adjustable cam drives , and vary the lsa to see how it affects it .

Edited by robert on 14th Jun, 2020.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM