55 replies to this topic

[Duncan VXR]

Think that covers it Paul Forgot about the sensor must look into that - not paying Regal prices - sure there are other companies that make them for less than that As Paul sataes one thing about the cams is that you run oe tappets so could be interesting to see what going more wild would be - also to go wild you would be entering the world of porting head etc and could get a bit silly

[siztenboots]

if i have done my sums right, then the x20xev inlet is about 5 degrees advanced, but same duration , more lift than the stock inlet . if you retard this by a full pulley tooth , you get ( 720 / 46 ) 15.6 degrees , and importantly much less overlap

Edited by siztenboots, 11 November 2009 - 04:45 PM.

[Exmantaa]

If this behaves similar like the C20LET (where the C20XE inlet cam with more lift could be used ), then retarding ~7 degrees (1/2 tooth ) gave better results. You need a vernier pulley to do this, or make some offset dowel. (There is a nice PDF article from Opel about tuning the C20LET for rally use. Reversion was a big problem with standard turbo and higher boost pressures, causing knock and high EGTs.)

Edited by Exmantaa, 12 November 2009 - 12:19 AM.

[siztenboots]

the piper exhaust cam definately looks interesting 50-10 240' duration and 9.58mm lift , that on its own would decrease the overlap by 10 degrees ( main cause of reversion ) that plus a cheaply sourced xev inlet has some potential. If I could find a OEM short duration exhaust cam even better. I am finding it very difficult to compare aftermarket cams as unless you have the crank timing details , you just don't know how much overlap you are going to get , yes you can adjust this on the inlet cam only with a vernier, or retard it a whole tooth , but not on the exhaust cam.

Edited by siztenboots, 12 November 2009 - 09:37 AM.

[Nev]

Cheeky, have you been for a RR session yet to see what difference these cams really make ? The reason I ask is that I am considering the profiles for my rebuild project, it would be good to have some facts to base my discussions on

Edited by Nev, 12 December 2009 - 10:33 AM.

[siztenboots]

looking back at what I posted a month ago , not sure I agree with my own comments one month on and loads of research , very little data about 2l , inline 4 is publicly shared, and people just blindly throwing in NA cams often wonder why they get the results. there is heaps of data from the yanks about big NA v8 etc for drag strips , but just lots of speculation about turbo or FI requirements anyway lets take the exhaust cam 50-10, it starts to open at 50' before BDC on the power stroke, and closing 10' before TDC = 50'+170' approx duration. Full lift is at the center of the lobe which in this case is timed at 110' before TDC. it has most lift than the standard cam. would it be better to shorten the duration further , say 40-20 , but more lift?

Edited by siztenboots, 12 December 2009 - 12:00 PM.

[Nev]

Steve, logic dictates that reducing the duration will help stop 'blow though' from overlap and the increase in lift should help the gases out, so I would agree with you. I am only speculating though and am no expert.

[slindborg]

Nev, you know who to talk to about this Lots of info from the Ford chaps on tuning 2l FI setups since they put the time and effort into making the engines go well from the start, whereas its been mere hobby tuners doing the vaux 2l FI stuff.

[siztenboots]

would it be better to shorten the duration further , say 40-20 , but more lift?

sorry , got that wrong, to have a shorter duration that should be 40-10 , 10' after TDC = 230'

LET stock its 7/64 and 50/20, both 8.5mm

as slindborg suggests, the infamous BD14 cosworth 16v cam , in 16/65 , ex 60/21 the lobe centres are at 115' and 110'

if using the hydraulic, then probably about 10mm valve lift is the limit.

a cossy group N ex cam is 50/11

Edited by siztenboots, 14 December 2009 - 11:49 AM.

[slindborg]

lift isnt the 'real' problem for hydraulics... its the ramp rates/duration + lift combo thats the killer. You can have a very wide duration high lift cam and stay hydraulic, but then go std lift and very slim duration which would kill the hydros. solid valvetrain sounds horny though!!!

[Duncan VXR]

Just ordered my set to collect next Thursday at the autosport show Be rude not to fit with the new rods / cambelt kit / water pump etc etc, been offered a gread deal on some arrows rods (very good) but there are some quite a bit cheaper, prob more than upto the job with the power I will be running but the quality of arrows stuff is really good! Autosport trade days could get expensive this year lol Interested to see the output, only worry is that I am not really happy with the quality of adj verniers available atm. Would have been nice to make some slight adjustments on the rollers. DG

[siztenboots]

Just ordered my set to collect next Thursday at the autosport show

Be rude not to fit with the new rods / cambelt kit / water pump etc etc, been offered a gread deal on some arrows rods (very good) but there are some quite a bit cheaper, prob more than upto the job with the power I will be running but the quality of arrows stuff is really good!

Autosport trade days could get expensive this year lol

Interested to see the output, only worry is that I am not really happy with the quality of adj verniers available atm. Would have been nice to make some slight adjustments on the rollers.

DG

what did you go for in the end?

[slindborg]

Just ordered my set to collect next Thursday at the autosport show

Be rude not to fit with the new rods / cambelt kit / water pump etc etc, been offered a gread deal on some arrows rods (very good) but there are some quite a bit cheaper, prob more than upto the job with the power I will be running but the quality of arrows stuff is really good!

Autosport trade days could get expensive this year lol

Interested to see the output, only worry is that I am not really happy with the quality of adj verniers available atm. Would have been nice to make some slight adjustments on the rollers.

DG

just kidney slot your current pulleys and do the bolts up tight once adjusted enough.

Fords etc dont have locator pins at all in their cam pulleys

[Duncan VXR]

It's a suprise Steve Still in final talks with myself on vx plans - only got a few weeks to get it all done but back on the road everyday again so road tyres for the next few months and prob take them off for Spa on May bank holiday. Will not take over this thread and start another thread Not had a good look at the current one so may just copy it and make my own tbh DG

[Duncan VXR]

Currently in discussion with James regarding a hotter reprofile of my cams this week and using the uprated springs. Spec details to follow

[Duncan VXR]

Obviously because I run a lot of boost I am after more lift that rally wild (in fact as much lift thats safe). Wild only realy work well with bigger turbine wheels (which I don't currently have lol) want to keep that long power curve. With BIG turbo the engine reacts more like a n/a relating to cams Been bouncing specs off a good friend who really knows his stuff and keeps me on the straight also knows from experiance its not all about figures as they react different on different engines etc See what James confirms tomorrow