Uprated cams - How important are they ?

[Ibiza sport man]

Looking at changing cams on an IHI big port engine to get more power at the top end but I suspect the engine is held back more by the turbo than the cams. Anybody tried alternative cams (back to back) and what gains did they get ?

Thanks

Bernard

 

[cupra_matt]

I think only Bill runs uprated cams, i may be wrong though.

But iam sure Bill was already producing 480 ish BHP before he changed them.

I dont think they are needed until you get up there with the big boys.

 

[ibizacupra]

lumpy idle.
mines not been dyno'd or mapped since cams fitted, nor bigger turbo installed so cant comment on gains.. top end is turbine restricted if thinking ihivf based unit. robs middle rpm band and puts some up top.

I want to check my cam to cam timing, as the lumpy idle is not supposed to be happening on mine, but does. vac on idle dropped by 1/2 what it was previously.

valve springs on aftermarket cams is my advised (and valves if not already done so) - i broke an exhaust spring last year (before cams). lucky it did'nt drop the valve. very lucky

3651 catcams seem popular on elitedubs and vortex with dyno plots of before and after if you want to searchy bernard.
regards
bill

 

[Wilko]

mine idles fine with the eurospecs bill.
vac is around 15 in aircon off

 

[ibizacupra]

yea mines down at 5 since fitting, was above 10 before.
special grind catcams in mine but not miles away from 3651's i dont think.

suspect cam timing is maybe not 100%

 

[Wilko]

Could be a vac leak too bill. Not many cams should idle under 10". Normal for the 1.8T is supposed to be around 18"
At 5" your brake servo will be suffering.

 

[ibizacupra]

Could be a vac leak too bill. Not many cams should idle under 10". Normal for the 1.8T is supposed to be around 18"
At 5" your brake servo will be suffering.

been like it since install..
not aware of any servo issue, feels normal.. did have a small vac leak from t'body gasket last race, but no effect on vac on gauge and was same as when first installed, quite odd.

specs of mine vs usual..
http://www.elitedubs.com/index.php/topic,1961.0.html

My specs... just so they're in the same catcams thread. - comparison
3651 -----> My specials
Duration: 245 / 262° ----->246 / 268°
Valve Lift: 8.25 / 9.95mm ----->10.00 / 9.25mm
Peak Angle: 113° / 108° ----->
Timing: -9/36° / 36/-1° ----->
Lift @ TDC: 0.30 / 0.95mm ----->0.26 / 1.51mm

 

[Wilko]

specs on my eurospecs courtesy of bob Q

 

[ibizacupra]

254' inlet 9.09mm max lift, 1.35mm lift at tdc
247' exhaust 10.38mm max lift, 1.26mm lift at tdc

3651 -----> My specials ------>Eurospec
Duration: 245 / 262° ----->246 / 268° ----->247/254°
Valve Lift: 8.25 / 9.95mm ----->10.00 / 9.25mm ----->10.38 / 9.09mm
Peak Angle: 113° / 108° ----->
Timing: -9/36° / 36/-1° ----->
Lift @ TDC: 0.30 / 0.95mm ----->0.26 / 1.51mm ----->1.26 / 1.35mm

more lift at tdc which should help cylinder fill on your eurospec ones john.
interesting differences between these.

are running a vernier wheel on yours john?

 

[Wilko]

Nope. Not yet.
Too many plans, not enough time. Not running at the mo. Water pump number 2 took a dump last week.
Just fitted a ross manifold, but not had it tuned yet. Larger IC and maybe ex manifold may be coming soon.
I keep thinking that I should just sell it and buy a 911.

 

[ibizacupra]

re-read bobq post on elite re mine... penny dropped re vernier pulley.