Compression - MX-5 Miata Forum

 

cliffs:

mazda millernia miller cycle uses a supercharger to do the hard compression work and leaves intake valves open during the first part of the compression stroke when the crank has no leverage on the rod/piston.

same ish could be done on a turbo, but not quite so much at light throttle where there's no boosts. super doesn't have to wait for exh gas to do its job.

big question: can you set up the VVT to close the intake valve so late that you gain efficiency with a turbo?

 

Damn I miss Pat

 

Light throttle means vacuum in intake mani. No need for boostin'.

 

Cool thread, thanks for the link.

 

intake valve open late means air pushin' back into the intake and less vacuum

 

That was very interesting

 

Correct less vacuumin' but no boostin'.

 

+1

 

yes, but basically having that retarded closing intake valve it would mean less probability to knock but A LOT of torque/power loss until the turbo will be able to fully spool, right?

 

PM Rick about your longings if you want, but please dont drag this up on the forums again.

 

So the 99/00 intake cam has the same duration and lift / ramps as the '01+?

If so how retarded is the 01 in full retard compared to the 99/00?

 

you'd have to degree both and compare I guess.

 

Why does the stock 01' need to move its intake cam around to match the 99 torque curve? Lack of VICS?

 

does it? do you ahve a stock 99 dyno plot?

 

When the 01 first came out FM showed that it was dead nuts same as the 99.

 

From FM:

VICS on a 99.
Here's our '99 with 600 miles on stock engine, FM single n/a exhaust. If you look at the chart, Run 29 is with hose disconnected and plugged for the VICS actuator. Major drop in midrange torque. Run 30 is with VICS hooked up normally. Run 31 is with VICS locked in the low rpm position, you can see that peak hp is the same, but hp plummets after about 6k rpm.
http://flyinmiata.com/tech/dyno_runs/99_050400.pdf

VVT on a 2003
Run 4 is VVT unplugged
http://flyinmiata.com/tech/dyno_runs...sconnected.pdf

99 vs 2001
2001 is Run 3
http://flyinmiata.com/tech/dyno_runs...ell_112700.pdf