924Board.org

[ideola]

Is anyone here running a "boost enhancer"?

More importantly, if you're running a boost controller, does the 931 waste gate still experience early and gradual bleed off of boost, such that a boost controller and boost enhancer would work in concert, or does the boost controller obviate the need for a boost enhancer?
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erstwhile owner of just about every 924 variant ever made

[Rasta Monsta]

I am running a Boost Tee, a product designed to provide zero signal to the wastegate until the preset boost level is reached. This is accomplished by placing a ball and spring into the feed side of the controller. It didn't work as intended, but had an interesting effect you might want to play around with (I ended up removing the ball and spring).

When the "enhancer" part of the unit opened, it wasn't able to fill the diaphragm of our monster 930 wastegate fast enough to immediately stop boost from building, so when running out a gear, boost would build up to about 2-3 PSI over what I had set, then settle back down. This actually had one benefit. . .max boost at 3,000 RPM and slightly less at higher RPMs. This MIGHT have the effect of getting a tad more oomph in the lower rev range in which the engine is less likely to detonate.

Theory only - YMMV.

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Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3

[ideola]

Interesting...is this in lieu of or in conjunction with a conventional boost controller?
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erstwhile owner of just about every 924 variant ever made

[924RACR]

Byron has one on his 951...
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[Rasta Monsta]

It was a feature of the unit. I don't know what you mean by conventional, but the Boost Tee is a boost controller that bleeds off pressure from the wastegate signal line to increase boost:



As for the ball-and-spring setup, the manufacturer refers to the design as a "gated boost controller." I was attracted to it because it is one of the few I found that didn't have a 90 degree pathway.
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Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3

[-nick]

I have a ball & spring valve (aka Grainger valve) I'm using as my boost controller. It does shut off any pressure to the wastegate until your preset boost is reached, but then the ball opens & closes to keep it steady. The effect is that boost cycles up and down by as much as 1psi in the upper rpms. The little ceramic ball has too much inertia to react quickly enough. There is also a small <1psi spike as you hit max boost.

Best method by far is an electronic controller.
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1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet

[9xx]

I have tried this one, it says "Boost Enhancement built-in"... I know that this controller is quite popular among 951 guys and one of the best manual controllers on the market. However, I was not that convinced about it.

http://boostsciences.com/accuboost.html

I couldn't get it under 1 bar with the original spring inside the gadget, I mean on the lowest setting. Then I found another one and with that new spring I got it from 0.8 bar and upwards. I would like to find a MBC that allows me to start raising boost from stock 0,65 bar and from there upwards (177hp series 2 Row engine).


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Mikko

All gone: 931 '82 Alpine White, original option "220" G31 with LSD + 3 x 944

[Rasta Monsta]

Mikko, try the Boost Tee. Once the ball & spring are removed, it works great.
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Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3

[flosho]

I have ran a manual boost controller for probably 2.5+ years. It works exactly how Rasta has described, the "boost set knob" puts a specific pressure on the spring which holds the ball blocking the route the air takes from the pressure pipe to the wastegate, until it gets to a certain point in which time it presses against the ball and collapses the spring, and feeds the wastegate, opening and allowing the boost to stop rising.

Boost comes on earlier and in my case would hold steady to redline.
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[This Space For Rent]

[ideola]

[Rasta Monsta]

If you are starting there, you should just install my 1.0 spring.
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Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3

[9xx]

[ideola]

[-nick]

I agree that using a 1bar spring is a good idea if you plan on running over 1bar anyway. But, I absolutely would not start with 1bar in a new performance build that has had lots of mods over stock. Start with 5-6psi and slowly work your way up.

I think I got my accuboost from Boost Sciences. I haven't checked to see how low it will adjust to, but I've had it down to ~6psi and it seemed to be able to go lower.

edit: ^^ you beat me to it - glad to hear of your approach!
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1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet

[924RACR]

Hmmm; seems like the MBC from Boost Sciences is more the right kind of thing to do, since we do have a dual-port wastegate... that said, I still prefer the boost-signal limiting feature of the check valve... a little of both would be ideal (short of an electronic controller)...
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype