924Board.org

collin41899 · Posted: Sat Nov 26, 2005 11:48 am Post subject: bad bov?

My 77 924 has an aftermarket rayjay turbo that was rebuilt. When i put the pedal to the floor i can see my boost level (on my boost gauge) rise to about 7 psi and at this point i am about at 4000 rpm's. The problem is when i am around this rpm i can hear the bov already letting out air and at the same time i cant go any faster because my car is backing off. This happens most in second and third and a little in fourth. I am geussing the sprng in the bov is bad? But there is proabably no way to find a spring that would fit in mine seeing as it is old and i have never seen anything like it.

So my question is do i need a new bov/spring or are there other issues involved?

I will try and put pics up (if i can figure out how) so u guys can see what my bov looks like.

Any help/suggestions would be greatly appreciated.

-Collin
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Collin
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yellow 1977 924 turbo!?!

CBass · Joined: 03 Nov 2002 Posts: 2807 Location: Vancouver, Canada

Replace it with an aftermarket BOV, or a used mitsubishi eclipse valve.
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'81 931 in various states of assembly

Paul · Posted: Sun Nov 27, 2005 5:46 am Post subject:

Is it the BOV or the wastegate that's leaking air?
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White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

collin41899 · Posted: Sun Nov 27, 2005 7:00 am Post subject:

bov...however i have never seen my wastegate.. dont know if my turbo ever came with one seeing it is older technology
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Collin
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yellow 1977 924 turbo!?!

Paul · Posted: Sun Nov 27, 2005 8:02 am Post subject:

Pictures please.

Unless the turbo is only capable of 7 PSI, it should have a wastegate.

If it's set for 7 PSI, it should leak exhaust at 7 PSI of boost.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

flosho · Posted: Sun Nov 27, 2005 9:45 am Post subject:

If your blow off valve is defective, or slowly leaking it wouldn't take much to fix, just find another BOV that would work with your plumbing.

It could also be the wastegate or wastegate line, it all depends but I would say its save to assume all turbo applications use some sort of wastegate, otherwise, you would be running the turbo at max psi all the time like Paul said...

I would also like to see pics of this set up.
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[This Space For Rent]

collin41899 · Posted: Sun Nov 27, 2005 2:49 pm Post subject:

ok..does anyone know how to post pictures??
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Collin
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yellow 1977 924 turbo!?!

Andrew NZ · Joined: 22 Jun 2004 Posts: 744 Location: New Zealand

From what I've read some of the early aftermarket turbo kits used a blow off valve rather than a wastegate and the turbo was at full speed all the time. It seems crazy these days, but I guess it was pretty new technology back then, so there would have been a lot of strange setups. The best solution would probably be ti fit a wastegate, if you don't already have one.
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Andrew
1977 RX924 race car
12a bridgeport supercharged
www.race4-dcup.co.nz

Paul · Posted: Mon Nov 28, 2005 1:30 am Post subject:

I've always called boost limiting valves in the intake system as "Pop off" valves which is what I'm guessing this car has.

If that is the case, it's probably working as designed.

This type of system must drive the fuel distributor nuts...
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

leadfoot · Posted: Mon Nov 28, 2005 6:01 am Post subject:

Yeah you'd want to make sure that air is getting recirced...
Are you sure that the wastegate is not internal...
At any rate you might have and adjustment nut on the top of the BOV, turn clockwise for more tension on the spring, counter clockwise for less.
Leadfoot
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1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress...

collin41899 · Posted: Mon Nov 28, 2005 12:55 pm Post subject:

i took the turbo apart and have never seen anything that would look like a wastegate..On the bov there is a spot on the top that an allen wrench can fit into..but it wont turn at al when u try to adjust it..ive tried with all my might..
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Collin
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yellow 1977 924 turbo!?!

Andrew NZ · Joined: 22 Jun 2004 Posts: 744 Location: New Zealand

Does this look similar to what you have?
http://cgi.ebay.com/ebaymotors/Porsche-924-Turbo-Kit_W0QQcmdZViewItemQQcategoryZ33742QQitemZ8018234759QQrdZ1
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Andrew
1977 RX924 race car
12a bridgeport supercharged
www.race4-dcup.co.nz

collin41899 · Posted: Mon Nov 28, 2005 3:54 pm Post subject:

YES!!! thats looks exactly like what i have..

do u or anyone know anything about his setup..

and possiblilties about the bov?
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Collin
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yellow 1977 924 turbo!?!

Andrew NZ · Joined: 22 Jun 2004 Posts: 744 Location: New Zealand

I've got one on its way over at the moment, but its the version with the wastegate. I've been trying to find out about them here http://www.924board.org/viewtopic.php?t=17300 but you might be best to do a search on BAE turbos. From memory there are a few posts on your system in the archives.

Did you get your car with the system fitted? Do you know how many miles it's done with it on etc?? I'm very interested in finding out as much as I can about the history of these kits.
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Andrew
1977 RX924 race car
12a bridgeport supercharged
www.race4-dcup.co.nz

collin41899 · Posted: Tue Nov 29, 2005 6:31 am Post subject:

yes i purchased the car with the turbo on it..It was seized and i got it rebuilt. Im not sure how many miles were on the turbo originally but i have put only about 1500 on it since the rebulit.

I also notice on the ebay site above it says its a bae turbo..However mine is a rayjay with no apparent wastegate..

strange..
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Collin
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yellow 1977 924 turbo!?!