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Rasta Monsta · Joined: 12 Jul 2006 Posts: 11732 Location: PacNW

I've had this bouncing around in my head for a bit. What do CGT replica guys do with the hood scoop? Are there any interesting functional designs? Has anyone finished the inside black, so it looks more like a functional scoop, or have people just left the inside body color? Also, for non-functional scoops, I wonder if people block the opening, or leave it open, parachute-style?
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

morghen · Joined: 21 Jan 2005 Posts: 9080 Location: Romania

i havent bothered with a scoop...i think it looks much sleeker with the NA hood. But this however creates problems like the manifold glowing

so the turbo hood or the CGT hood is needed for a factory turbo engine..i plan to create a route for air from the front to be delivered to the manifold to replicate the conditions of the factory desing....but no scoop.
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ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

leadfoot · Posted: Tue Dec 02, 2008 5:50 pm Post subject:

It does help vent a little air through the engine bay and damn does it make the car look angry. Definately has a bit of that "muscle car" look about it. Kind of like a peugot 405 with an outrageously large spoiler on it.
http://video.google.com/videoplay?docid=2991678896068476162
damn I love that video...
Stu
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1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress...

Joes924Racer · Posted: Tue Dec 02, 2008 6:06 pm Post subject:

I have a nice new hood & I dont think Ill put any type of scoop on it for awhile.

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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.

Vince Ponz · Joined: 02 Nov 2002 Posts: 3581 Location: Florida

I guess it serves the same as a turbo hood has a naca duct in it. Depends on a few factors. Drivers side to provide fresh air to carbs if you have them. Pass side to cool exhaust.
Some like the looks personally I don't. That is why we are here. We have different likes etc. One thing for sure we learn a lot good or bad.
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"Never let them see you sweat"
77.5 924 modified track car
79 931 Euro stock
88 924S SE
87 911 Targa stock

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11732 Location: PacNW

So nobody here is running one?
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

leadfoot · Posted: Wed Dec 03, 2008 10:47 am Post subject:

not any more, but I was...
it was fiberglass and not painted inside.
In conjunction with a number of other airflow mods i.e improved frontal area for intercooler/radiator/oil cooler and ducting for alternator and starter this help lower underbonnet/coolant/oil temps.

Interesting to note how much heat is dissipated out of it when stopped at an intersection... awesome to look at on a cold morning.

It's up for debate as to whether having a higher pressure zone created just behind the radiator actually adds or detract from efficient cooling.

Only way to find out would be to mount some temp probes and a camera with some ribbons pinned to the underside to measure direction of the airflow. If they go everywhere then it's just adding turbulence, if it's directional then at least you can see where the airs going.

One other thing you could try is to block the gap between the firwall lip and bonnet completely. If your temp probes increase then removing some of the height off the firewall lip would also help with cooling.
Stu.
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1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress...

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

morghen · Joined: 21 Jan 2005 Posts: 9080 Location: Romania

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

When I first acquired the wide body car, it did not have the original turbo hood, even though the VIN confirms it is a bonafide S1 931. The manifold NEVER glowed on it, even after driving it home from Covington IN for 5+ hours. It did have an intercooler, although I'm not sure how effective it was, and it was also running very rich.

Flames shooting out of the exhaust and red hot manifold sounds like more than just an engine compartment airflow issue, it sounds like a mixture problem to me, and one that your narrow band may be insufficient to diagnose.
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erstwhile owner of just about every 924 variant ever made

morghen · Joined: 21 Jan 2005 Posts: 9080 Location: Romania

i'll get a wide band test as soon as i travel home.
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gegge · Joined: 27 Jul 2007 Posts: 1124 Location: Sweden

morghen:

If the exhaust is glowing and you are running rich to the extent that black smoke and/or flames are visible - I would say that the timing of the ignition is too late and you got parts of the combustion in the exhaust manifold.
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Carl Fredrik Torkildsen

924 turbo -81 Carrera GT RESTOMOD
924 turbo -80 Dolomite De Luxe
924 -85 DP kit, BBS RS, M030 and tuned engine
924s -86 Black on black turbo with Fuchs

morghen · Joined: 21 Jan 2005 Posts: 9080 Location: Romania

sorry to highjack, Rasta

guys, i have some topics on this glowing manifold thing in the 931 tech section.
But since we're talking....the manifold only glows when i go at WOT for a while...the water also rises a lot when going at high speeds for longer periods. (high speeds means over 140kmph) and if i keep it at 200+ for a while the water will boil...didnt test this but its a sure guess.

I'm thinking the timing might be way retarded and the combustion temps are too high...but i cant do anything about it since its an S2 and the "MAGIC TIMING RETARD WIRE" does not work for me. Manifold glows with or without the wire...performance is the same...feels better without the wire tho. Anybody got any ideeas how to check the total advance ?

On the other hand...the car starts, drives and sounds great....so it might just be the lack of ventilation glowing the manifold and the unburnt/rich gases fireing up because of that.

I'm going for VEMS soon but that costs....well...alot

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elitejaso · Joined: 24 Jul 2007 Posts: 138 Location: Melbourne

My cgt project is on hold for the moment but with my scoop im planning to paint the inside of it black as it looks mean with the guards red.

Saw it on a gts in a 911 and porsche world magazine
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1981 924 turbo (daily driver)