Rallye and XSi cam specs

[sandy309]

Sorry I missed that question... as I mentioned before, I measure the lift at the valve with digital DTI to 0.0005" accuracy, degree by degree of cam rotation. It's laborious, but gives me a wealth of information about the profiles.

[simon182]

Sandy, Have you ever measured a Piper300 rally Rallye cam? the advertised lift is 10.16mm - how accurate is this figure?

[rajjinator]

Sandy, Have you ever measured a Piper300 rally Rallye cam? the advertised lift is 10.16mm - how accurate is this figure?

why not just measure the lift with a DTI?

[simon182]

why not just measure the lift with a DTI?

because ive not had chance yet! :P And i wondered if anyone had done it on my Cam before! - it could save me some time!

Piper are useless at replying to emails too!

[rajjinator]

because ive not had chance yet! :P And i wondered if anyone had done it on my Cam before! - it could save me some time!

Piper are useless at replying to emails too!

lol.. wont take long to measure!

[simon182]

lol.. wont take long to measure!

Depends on how many points you measure!

:P

[simon182]

Right then:

S1 J cam measured!
Direct from the cam, Was doing this to compare to my 300 Duration Piper jobbie....
(which is actually for the quiksilver/early VTR not a rallye! - self inflicted for not checking before I bought it - see the for sale section)




Does anyone know the cam to rocker ratio?? 1.4 rings a bell...

OK,
now im confused,

Ive measured a max lift of 6.7mm (ignoring base circle) giving a Valve lift of 9.38mm (ratio 1.4:1)

but Sandy gets a peak valve lift of 10.6mm....

Pipers lairiest cam gives an advertisd lift of 10.42... (including ratio)

So whose right... me or sandy?

:S

[sandy309]

I always measure at the valve, which takes the full effect of the rocker shape and ratio into account; as long as the gauge is firm and zero'd correctly, it can't be wrong. What can vary, although not greatly, is wear on the cam and/or rocker pad.

[simon182]

Does that not make it really hard to measure?

i.e. getting the DTI directly in line with the direction of travel of the valve?

I guess there just different ways of measuring the same thing - so long as I use the same method for measuring when comparing cam profiles all will be ok.

[sandy309]

Yes exactly. I use the same method every time and measure/check every cam I use to ensure consistency etc. Aligning the DTI isn't hard or super critical and obviously check you have full travel over the profile.

[pugmadnath]

What is the difference in performance gain between a longer duration and higher lift?

For example, what advantage would a 300 degree duration camshaft have over the standard one, if it produced the same lift as standard?

[mcd240]

The Newman PH4 actually lifts the valve 11.5mm peak, the specs they publish on the site doesn't seem to correlate in an obvious way with the actual profiles I've received. I don't know why that is and I'm not complaining, because the profiles I've had from them so far have been closer to what I wanted than the actual spec. I've plotted the curve for the PH4, I do it for every cam I use to help me develop the rest, but I don't know that my various cam suppliers would be too chuffed if I published their profiles publicly! If they weren't concerned, I'd imagine the curves would be available already, I wish they were.
Cams from different manufacturers are quite different and what some of the manufacturers make for the specialist engine builders are quite different in many to what's publicly available. But clever cam design/choice isn't much use without knowing what else is needed anyway.

What you said about the actual lift of the cam makes sence to me i have a 8v roller rocker head on my 1400 and have a one off cam based on a ph 4 newman cam with that sort of lift but confused me because it did not tie up with valve lift on the spec sheet. DTI gauge is never wrong! Just to be cheeky i added a link to my timing problem am having is anyone cam help many thanks.

http://www.106rallyeforum.com/forum2...hlight=timming

[stockhatch 123]

has anyone compared VTR cam to the Rallye cam is there much difference? (later model VTR)

[Bastek333]

I've measured the inlet side of the cams, exhaust to follow. The 1.3 Rallye, 1.6 Rallye and 1.6 XSi all use the same cam, stamped "J" on the flywheel end. The 1.4 XSi uses a different cam, stamped "Z" on the flywheel end.
Headline specs:
"J" cam:
Peak lift 10.6mm
Duration at 0.1mm lift 270 degrees
Duration at 1.0mm lift 235 degrees

"Z" cam:
Peaklift 10.3mm
Duration at 0.1mm 270 degrees
Duration at 1.0mm 234 degrees

.

I have found that topic looking for some info about PTS camshaft - i have bought one advertised as PTS but .... i'm not sure about it....

Did comparison my J shaft to new one and .... please take a look on pictures above and tell me which one is better as i'm confused








I will appreciate and comments about both cams ... as i'm going to increase CR now when head is on the table

[sandy309]

You need to measure lift at the valve, rather than off the lobe, to see what it does.