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Cedric
Joined: 27 Aug 2004
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Location: Sweden
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Mike9311
Joined: 14 Dec 2004
Posts: 1793
Location: Chicago-ish
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 Posted: Fri Jan 31, 2025 6:31 am Post subject: |
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| Cedric wrote: | | Interesting, what spec? |
I will say I am weirded out by the widening of the lobe separation but I like how they did it by just moving the exhaust event earlier (or later depending on how you want to visualize it). Based on my flow numbers and exhaust valve size, I felt like I needed some favoring of the Intake side
Plus, its so much work to set up the new valve clearances so I figured let me try something since I am shortening stems and using caps with new tappets
Cat Cams 5220021 which was also purchased by Dutchpug for his insane NA Turbo build but I don't know if he ever tried it??
Specs and also laid over the stock curves. I guess they say the stock separation is 110 but I have also seen 108
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1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car |
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Cedric
Joined: 27 Aug 2004
Posts: 2742
Location: Sweden
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| Posted: Sat Feb 01, 2025 1:08 am Post subject: |
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| Mike9311 wrote: | | Cedric wrote: | | Interesting, what spec? |
I will say I am weirded out by the widening of the lobe separation but I like how they did it by just moving the exhaust event earlier (or later depending on how you want to visualize it). Based on my flow numbers and exhaust valve size, I felt like I needed some favoring of the Intake side
Plus, its so much work to set up the new valve clearances so I figured let me try something since I am shortening stems and using caps with new tappets
Cat Cams 5220021 which was also purchased by Dutchpug for his insane NA Turbo build but I don't know if he ever tried it??
Specs and also laid over the stock curves. I guess they say the stock separation is 110 but I have also seen 108
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Its an interesting cam, my cam simulations definitely preferred a conservative exhaust vs inlet cam ratio. The log manifold restricts the freedom a bit on how wild cams you can use, and even more mabye is the turbo sizing/choice. The smaller and/or less efficient the higher the backpressure and residual gas pushback, the more restrictive you will have to be with overlap and the exhaust cam duration.
I would like to have a "stage 1 ish" cam, but im not sure my Kjet could match the higher RPM flow rate.
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1980 924 Turbo
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Mike9311
Joined: 14 Dec 2004
Posts: 1793
Location: Chicago-ish
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| Posted: Sat Feb 01, 2025 11:55 pm Post subject: |
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I agree with your thoughts entirely.
As far as the Kjet, didn't FastEddie figure out it could support somewhere around the edge of 300HP? Or are you worried about how it handles it down low at idle and such? I know both Lildude, Dan, and CarreraRSR ran Stage 1 cams. Tyler and Dan had the Integral and Steve had Piper. I drove the CS before I owned it, albeit with moderate boost, and it seemed fine. That experience was very noisy so there was also a lot of distraction with only a tiny bit of carpet, firm suspension, and exhaust. Polar opposite really from the GT which, for lack of a better term, was perfectly "GT". I loved it all of course. ...When I tore down the CS engine, a cam lobe or two didn't look perfect. I could even see it in my scan. Figured lets try something else
Back to your comments. I guess the only thing I would have to worry about is if I ever build a nice turbo header. That is not likely in the near future.
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1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car |
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Raize
Joined: 18 Sep 2013
Posts: 337
Location: Scotland
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| Posted: Sun Feb 02, 2025 6:57 am Post subject: |
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| Easy way to test if you've some K-Jetronic headroom left would be to adjust the WUR intentionally too rich and see if it can maintain the excessively rich mixture to redline (assuming you aren't already running 10:1 which given it is a 931 may be the case...) |
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kondzi
Joined: 02 Jul 2018
Posts: 494
Location: Poland/EU
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| Posted: Wed Mar 19, 2025 1:08 am Post subject: |
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CIS can supply a LOT of fuel. But can it do it when it’s needed adequtely? I’m not 100% sure.
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Konrad
'89 951 US
'88 Mustang 5.0 LX Convertible (factory specs)
'84 911 Carrera 3.2 RoW (factory specs)
'81 931 RoW (TBD)
'81 Ford Capri 2.8i (factory specs)
'79 Ford Capri 2.9 (heavily modded) |
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