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Location:
Perth
Registered:
October 2002
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Cam gear effectiveness on stockish motor?
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Thu, 03 February 2005 06:35
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I'm picking up some cam gears for the 1JZ next week and just wondering if it's worth puting on yet, or waiting for further mod's.
That is, with stock cams, turbos, etc., will the cam gears significantly move the powerband around? Power mods are: ECU, EBC, FMIC, exhaust.
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Location:
Pilbara
Registered:
November 2004
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Re: Cam gear effectiveness on stockish motor?
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Thu, 03 February 2005 07:06
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Cam gears will not really give you all they can without also using an aftermarket ECU mate.
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Location:
Perth
Registered:
October 2002
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Re: Cam gear effectiveness on stockish motor?
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Thu, 03 February 2005 07:10
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After market ECU, I got. But what I'm wondering is the extent the powerband can be moved when cams & turbo are stock. With a modest total power graph (say, 200rwishkw), would any movement of the powerband be perceptable?
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Location:
On your mum!
Registered:
May 2002
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Location:
Lost in the K hole
Registered:
May 2002
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Re: Cam gear effectiveness on stockish motor?
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Thu, 03 February 2005 07:45
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stock motor = runs best with stock timing
the mods you listed will benefit SFA from having adjustable cam gears.
all changing the timing does is more the rpm band up and down. if EVERYTHING on the engine is tuned for a given powerband, why try and move the band around with timing changes - youll go backwards
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Location:
Perth
Registered:
October 2002
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Re: Cam gear effectiveness on stockish motor?
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Thu, 03 February 2005 07:57
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Thanks guys, I've got something to ponder now. I've also found a few articles on cam timing to read over the weekend. Though it sounds like the cam gears will be yet another bolt-on that I won't be bolting on for a while.
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Location:
Canberra
Registered:
November 2004
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Re: Cam gear effectiveness on stockish motor?
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Fri, 04 February 2005 00:00
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I havent personally played with adjustable cam gears, but I have talked extensively to the RB25 owners about the effects of adding the adjustable cam gear to the exhaust cam of their engines (RB25DET's have VVT on their intake cam). They seem to agree that there are modest gains to be had, around 5 or so kw across the entire rev range, as well as quicker turbo spool. This is with stock camshafts and the same mods you list. Bear in mind that they have had a retune at the same time to suit the adjustable cam gear changes.
I know these results aren't a 1JZ, but my money is that with a good tuner you'll get some gains, just dont expect an additional 50 rwkw.
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Location:
Sydney
Registered:
March 2003
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Location:
On your mum!
Registered:
May 2002
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Re: Cam gear effectiveness on stockish motor?
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Fri, 04 February 2005 02:18
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so which run was which?
I would have the Orange power curve over the Red any day and every day.
(IF the red one was the one that felt faster then it was only due to the steepness of the curve.)
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Club President
I supported Toymods
Location:
Sydney
Registered:
May 2002
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Location:
Sydney
Registered:
March 2003
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Re: Cam gear effectiveness on stockish motor?
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Fri, 04 February 2005 03:46
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| thetoyman75 wrote on Fri, 04 February 2005 14:04 |
Ouch,
Loosing all that power under the curve where the car is driven most is hardly worth a peak increase of 9rwhp.
It will feel better from the ass dyno perspective as now it has a more "peakie" power curve due to it making LESS power at lower RPM. Ie now what you feel is the hole you created in the power curve not so much the power "increase".
Theoretically you should have been able to adjust the caming in the other direction to create MOPRe power under the curve atthe expense of a little top end power, yeilding a smaller number on the top of the page but a Faster vehicle. Cam timing for improved bottom end results generally assists in turbo spool up time as well 
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I love Theoreticals  , seriously though the changes it made to the curve wasn't really worth it as far as the general curve ended up, BUT the question was, can the curves be moved around with cam changes, and yes it can, whether or not it's detrimental to the overal curve is another story.
I'm sure things would have changed with more boost.
It was a stock sequential setup, they make boost off idle
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Club President
I supported Toymods
Location:
Sydney
Registered:
May 2002
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Re: Cam gear effectiveness on stockish motor?
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Fri, 04 February 2005 05:42
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Stenno,
The 2JZ is a very different animal to an RB25, the theoretical listed above is actual for an RB25/RB26 we did one last week.
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Location:
Canberra
Registered:
May 2002
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Re: Cam gear effectiveness on stockish motor?
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Fri, 04 February 2005 06:22
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I have played with the adjustable gears on my 4AGTE with stock cams, and agree with Rod that the seat of the pants dyno can make it feel a lot stronger (and it probably was in the last 1500rpm), but have a detrimental effect on power at the lower end of the revs. 
I advanced my inlet cam 5 degrees, and retarded the exhaust 3 degrees, which made boost come on later in the rpm, and power to hit very savagely at around 4500rpm, then scream to redline.
Whilst this was not done on the dyno, several 400m acceleration runs were measured before and after, and with the adjusted cam timing, terminal speed at the end of 400m was down by 6mph (10kph), reflecting the fact that its all about power under the curve, not peak 
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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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