Increasing Boost With Revs? Airflow?

[R32 TT]

Do any of the boost controllers allow you to set boost levels depending on RPM?

For example - supposing I want to limit boost to 1.2bar at 5000rpm and slowly ramp boost up to my maximum boost of (for arguments sake) 2bar at 8000rpm?

The reason I ask the question is that since boost is "resistance to airflow", as you go up the RPM range, the valves are only opening for much shorter periods, and so while you are reading say 1 bar at 6000rpm, you're probably only getting half the amount of air in as you are at 3000rpm when also running 1bar... ( is that theory right?)

So I was thinking that an engine under load 4000-5000rpm might not like 2bar being belted into it, (a bit like a shot of nitrous too early in the revs) but could well handle it up around 7000-8000 rpm?

If a boost controller is set at 1.5bar to "suit" the 4000-5000 rpm range, then am I getting less and less air into it at higher revs as the valves are opening and shutting faster and faster and hence building up back pressure? (ie reading same boost, but getting less air-flow?)

Thoughts?

[Driver]

doesnt the pfc boost controller do that?

one of them does i cant remember which one.

[krzysiu]

ACV-R can do that in intervals of 500rpm

[R32 TT]

ACV-R can do that in intervals of 500rpm

<{POST_SNAPBACK}>

Ah - so it does! (just looked it up)

I have a basic HKS boost controller which doesn't - and I only ever see people quoting max boost.... so I wondered if this sort of thing was played with much..

Sorry if it was a dumb question! I come from a normally aspirated backgorund and am still learning.

So would this be the norm then?

Are people out there tending to raise the boost as RPM goes up?

cheers,

[Abo Bob]

The reason I ask the question is that since boost is "resistance to airflow", as you go up the RPM range, the valves are only opening for much shorter periods, and so while you are reading say 1 bar at 6000rpm, you're probably only getting half the amount of air in as you are at 3000rpm when also running 1bar...  ( is that theory right?)

<{POST_SNAPBACK}>

An engine at 6000 rpm is eating twice as much air as it is at 3000 rpm. That has nothing to do with boost.

Some people, myself included, use the rpm based boost control of the AVC-R to smooth the ramp up of boost to control wheelspin in 1st gear.

[kingsley]

An engine at 6000 rpm is eating twice as much air as it is at 3000 rpm.  That has nothing to do with boost.

Some people, myself included, use the rpm based boost control of the AVC-R to smooth the ramp up of boost to control wheelspin in 1st gear.

<{POST_SNAPBACK}>

You don't have to do it that way - the AVC-R has a gear learning facility and you can use that to limit boost differently per gear. That way, you can have your full balls out mode in the higher gears while limiting it in 1st to stop wheelspin.

I think it works out what gear your in by looking at rpm vs road speed.