CTSC expected boost out of gear?

[TomCat]

I (think) I have completed my installation of a CTSC low boost 1.6L on a 1991 NSX...BUT I am not able to create positive boost?
While on the lift, out of gear, I have run the engine up to about 4,000 rpm and although my aftermarket mechanical vacuum/boost gauge moved up above the idle reading (20 in.hg. of vacuum) to about 15" it seems to go back to 20".

I tried putting a little load on the motor by engaging the gears and running/spinning the rear wheels (off the ground) up to about 80mph...but still I could not seem to get boost...is this normal or do I have a problem...thanks.

I guess the question is, do I need to have a real "load" on the motor to make the CTSC show boost?
Tom

 

[MvM]

I believe you should ALWAYS have boost, at least above 2000 rpm.

The CTSC is driven by your crank so even at idle it is spinning already.
Are you sure you don't have a leak somewhere ??

 

[junior40er]

you still need a load..even with a SC. I noticed that myself after having gauges put in.

 

[RYU]

it's difficult to build "boost" when free revving at idle. drive it out on the street!!!

 

[TomCat]

I believe you should ALWAYS have boost, at least above 2000 rpm.

The CTSC is driven by your crank so even at idle it is spinning already.
Are you sure you don't have a leak somewhere ??

I feel the same way...sc screws are turning...some pressure should be building...at least that is how it seems

- - - Updated - - -

Do you know why? What mechanism prevents/bypasses boost without a load?

- - - Updated - - -

Why is it difficult...do you know the mechanism that prvents boost under low/no load?
I see/feel/hear NO obvious leaks.
I am getting a CEL but have not pulled codes.

 

[goldNSX]

Yes, you need a real load. It's designed this way. The diaphragm under the intake bridge closes only under a vacuum that is high enough. You get this vacuum with a throttle being more open than just cruising around. But: the lower the revs the less throttle it takes. If you drive around with a light trottle there's no boost built up because the diaphragm routes the air from the screws route back to the intake side through the aluminum hose, so no boost.
I can hear the change in sound of the SC while being in boost as it has to work harder for boost.

During idle you only can get boost for a very short period if you blip the throttle fast enough. But as RYU said, go for a drive on the street as you need a load and therefore vacuum high enough to activate the SC.

BTW I like this behaviour pretty much as it lets the engine having two stages, NA (light throttle) and boosted (heavy foot). Power on demand.

Oh, and the unit always boosting reminded me of the funny idea of the so called 'direct forced induction' or how it was called.

 

[RYU]

What goldie said ^^^

To add.. the vacuum actuated bypass valve which diverts the intake air via the tube on the bottom that you installed is BRILLIANT. That's why you get stock-like gas mileage when you're tooling around town or going on long highway trips.

I have an exhaust system that works the same way. Only under load does it open up.

 

[kookoo4nsx]

Why didn't you simply apply some brake?

 

[TomCat]

Thanks all!