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Location:
Adelaide
Registered:
June 2002
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Re: Cam gear effectiveness on stockish motor?
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Fri, 04 February 2005 19:20
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I've had a bit of success re-timing the cam in my 1FZ-FE Turbo motor. The cams and runners are obviously set up for 4WD type activities, so the peak torque was at 3600. I was looking at the chainwheel and noticed that I could retard the cam 3 degrees pretty easily. When it was fired up again, the motor would free-rev more snappily and seemed a bit happier in the top end (like over 4800 rpm-'top end', ha, ha). On the dyno, there was a slight reduction in bottom end torque, but with the amount of torque the 4.5Litre pumps out it didn't hurt much-it just meant it fried the tyres a little later in the run. What it meant was that it pulled noticeably harder at the strip from 1/2 to full track.
As was mentioned before, only muck with the cam timing to increase the area under the power curve. A car with a large area under the curve (instant torque production) will always annhialate a really peaky car with a ton more peak power.
As an example, my crown has currently run 11.04@125 mph and it weighs in at a good 1600kg with me in it. Surprisingly, the crown ran the time with only 281rwkw. There are heaps of lighter cars with a stack more power around, but they all seem to struggle to crack mid 11's. I've been curious to work out why-and it seems that although they have the peak power, they have a smaller area under the power curve. Have a look at how much power some of the R33's make to run mid 11's-usually stacks more than 281!
If you want a car that is fast-not one that feels fast-you need to get the engine torquing as early as possible in the rev range.
Another example is my mates 250 turbo cortina. With 4.0L and 14 psi through a modded series 5 rotor turbo, the car was being choked by the smallish exhaust housing and would max out at about 170 rwkw on the dyno. Keep in mind though that it was redlining at 5500rpm-with the engine hitting 150 rwkw by only 2100rpm. With 1400kg to shift it doesn't sound too exciting-but the constant torque allows it to cut 11.7sec 1/4s on crappy street tyres(not even stalled up).
You should be able to get a bit of extra grunt, but with everything else stock I don't think it'll be much. The real benefits will come when you are using a bigger turbo and other intake mods.
My guess is that you'd want to set up the cams to attempt to match the cam range with the peak efficiency region of the snail (a real trial and error process probably)
Anyway, take it easy
Sean
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| | Subject | Poster | Date |
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Cam gear effectiveness on stockish motor?
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Celia-Sue | Thu, 03 February 2005 06:35 |
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Re: Cam gear effectiveness on stockish motor?
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bunkyT18 | Thu, 03 February 2005 07:06 |
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Re: Cam gear effectiveness on stockish motor?
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Celia-Sue | Thu, 03 February 2005 07:10 |
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Re: Cam gear effectiveness on stockish motor?
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YelloRolla | Thu, 03 February 2005 07:18 |
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Re: Cam gear effectiveness on stockish motor?
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ed_ma61 | Thu, 03 February 2005 07:45 |
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Re: Cam gear effectiveness on stockish motor?
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Celia-Sue | Thu, 03 February 2005 07:57 |
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Re: Cam gear effectiveness on stockish motor?
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Silver_r33 | Fri, 04 February 2005 00:00 |
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Re: Cam gear effectiveness on stockish motor?
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Stenno | Fri, 04 February 2005 01:50 |
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Re: Cam gear effectiveness on stockish motor?
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YelloRolla | Fri, 04 February 2005 02:18 |
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Re: Cam gear effectiveness on stockish motor?
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thetoyman75 | Fri, 04 February 2005 03:04 |
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Re: Cam gear effectiveness on stockish motor?
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Stenno | Fri, 04 February 2005 03:46 |
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Re: Cam gear effectiveness on stockish motor?
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thetoyman75 | Fri, 04 February 2005 05:42 |
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Re: Cam gear effectiveness on stockish motor?
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TE72_Turbo | Fri, 04 February 2005 06:22 |
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Re: Cam gear effectiveness on stockish motor?
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MS-75 | Fri, 04 February 2005 19:20 |
