View Full Version : 7m Stock Cam Profile... *cool graphs*
taken directly off my cams with a dial gauge
- 0deg is TDC at the top of the powerstroke
- 360deg is TDC at the top of the intake stroke
- lift is about 300thou
- lobe centres (measured as crank angle) are 255deg (EX) and 455deg (IN)
- total duration, as measured @ 10thou (basically what duration the valve experiences once you deduct shim clearances etc) is 255deg for both intake and exhaust. (10thou is the dotted line on the top graph)
- duration @ 50thou lift is something utterly crappy like 150deg
- valve overlap is SFA
hope this is useful to someone!
Not to me, but it looks good :)
How did you obtain the data?
25-08-03, 10:24 PM
How did you get from dial guage measurements to cool graphs on a computer?
I want you to do that for some of my un-known cams!
data was obatined by setting up a dial gauge on the head, with the cams installed (without valves and springs etc) and also with the cam gears installed. the dial gauge was zeroed on the base circle of the lobe for reference.
the cam gears have 48 teeth, which corresponds to 7.5deg per tooth (or 15 'crank' degrees per tooth).
After identifying TDC on the compression/power stroke, using the keyway in the cam gear (and the gear's corresponding tooth) i then just rotated the cam gear one tooth at a time, and recorded the dial gauge measurement.
this gave 48 nice datapoints which ive plotted above :D
i then installed 1 IN and 1 EX valve, and remounted the dialgauge on the face of the head (with the tip on the valve face) to cross check my raw cam data with real valve opening data, and confirmed that I had TDC and all the other cam timing correct. this also gave me the info regarding the 10thou difference between cam profile and valve actuation - which demonstrated the 'true' duration of the cams...
then i just whacked it all in excel...
the cirular graph was just a stroke of luck - called a radar graph. turns out that when i set the Y axis range to include the dimension of the base circle diameter of the cam, the plot ends up completely (and being dimensionally accurate) representing the exact raw cam data that i collected in the first place - making it graphically representative of the 'actual' cam (excpet it rotates backwards...)
am more than happy to do other cams :)
its good fun actually 'seeing' the cam profiles
I woudl be interested to see you do this with 7MGTE cams... and possibly overlay the data :)
if i can get some 7mgte cams ill do it
ill also be doing:
2jzge and 2jzgte stock items
might even get a change to dial up daves 305deg 2jzge ones before he installs them...
would have been nice to do stenno's TRD units... :(
using the specs i plotted above, i just jumped into my dyno software, and by playing with the cam timing as follows:
retarding EX cam 8 deg (now EVO 54.5deg BBDC)
advancing IN cam 6 deg (now IVO 18.5deg BTDC)
resulting lobe centre angle 108deg
valve overlap 39deg
ICA ATDC 109deg
ECA BTDC 107deg
I netted an extra 12hp @ 6500 (difference emerges @ 4500)
and an extra 5ftlbs @ 2500-4000, and 8-10ftlbs from 5500 to 7000
not bad for a nights work :D
26-08-03, 10:14 AM
I'll try and get the dial indicator on to the big cams on the weekend. They are sitting in the head all done!
PM Stenno about 7MGTE ones, he may have some still.
Powered by vBulletin® Version 4.2.0 Copyright © 2013 vBulletin Solutions, Inc. All rights reserved.