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Author Topic: Cam timing on Vw16v turbo  (Read 3935 times)

Offline stan

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Cam timing on Vw16v turbo
« on: December 17, 2010, 05:44:27 am »
Hi guys I am new to Vems.I run a16v Turbo motor fitted with 250 inlet /260 exhaust cams.They are set at 1.05mm Inlet-1.25 mm exhaust at TDC.Please pass yre opinions on these settings as i dont feel it is spot on yet.The motor is fully built,studs,steel rods T3/T4 turbo,70mm t/body,forged pistons.720cc injectors etc.The exhaust is very short-750mm and 63mmOD,it is in a rear engined sports car ,purely for motorsport.Please give yre opinions and advice.
Many thanks-Stan
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Offline GintsK

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Re: Cam timing on Vw16v turbo
« Reply #1 on: December 17, 2010, 08:42:24 am »
IMO best way is to find cam timing on dyno. Is it too difficult on this engine?

Adjust VE map on your current cam position. It can be some % off. Main target here is stable Ego correction with no sharp jumps during WOT run.

Now you can perform some dyno pulls with Ego correction on. VEMS has quite fast and reliable closed loop correction. Fast enough for keeping target during pull if VE table is good.
Of course keeping lambda and ign maps conservative during these measurements is good idea. And may be better with open loop boost control for good repeatability.
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Offline Sprocket

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Re: Cam timing on Vw16v turbo
« Reply #2 on: December 17, 2010, 05:08:29 pm »
What does the lift at TDC relate to in degrees at full lift? Unless you have the data for the cams, the lift at tdc values mean little to anyone other than those who work with that engine and cam.The values vary with cam profile and lift.

I have researched many turbo 16v motors to try and get a general timing figure to start with for my hybred build, at full lift and it would appear its around 112 degrees.

Have a look for your motor on http://www.kentcams.com and look at the timing values. then, if the did not do a turbo version of this motor, look for other manufacturers motors and look at their data. But as has already been said, the best way to find a suitable cam timing value is on the dyno swinging the cam timing by 2 degree increments and power runs, to be able to draw a comparison and decission on which values are best suited. You at least need a reasonable palce to start, which might not be the stock figure, if the motor was normally aspirated originaly.
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