DFZ camshaft for 2.0 T engine ?!

[DamirGTI 364]

Yes i know ! .. we like DKZ and RFX (XU10J2) item as an upgraded cam for standard 2.0 T cam . 

But what about DFZ cam ? 

 

Went trough my pile of cams , and as it appears pretty much all of the three 2.0 T cams which i have have some sort of "issue" (pitting/corrosion) , one not as bad but not that great either . 

 

Other than that i have at least three DFZ cams all in good condition , two DKZ cams with worn lobes so scrap value aka no use , one good RFX (XU10J2) cam and a few 1.6/1.9 Gti cams .

 

For now , the plan was fitting stock 2.0 T cam first .. as I need to run in the engine , fix and sort out some LPG system items stuff certificates and so on , and much deviation from standard especially in terms of fuel mixture and such is best avoided at this stage when the engine is freshly rebuilt . 

Not sure how much would RFX (XU10J2) cam throw the mixture off , and if the shift of the rev range/power band will be even good for a big/heavy car , the 406 .. cannot tell till i try how it goes with stock cam first . 

Then second close to the OE 2.0T cam seems to be DFZ . 

 

So if specs are as follows ; 

 

XU10J2TE , RGX
Intake duration @ 0.050" : 212°
Maximum intake valve lift: 0.381" : 9.677 mm
Exhaust duration @ 0.050" : 218°
Maximum exhaust valve lift: 0.432" : 10.973 mm

 

XU10J2 , RFX
Intake duration @ 0.050" : 219°
Maximum intake valve lift: 0.432" : 10.973 mm
Exhaust duration @ 0.050" : 219°
Maximum exhaust valve lift: 0.432" : 10.973 mm

 

DFZ
Intake duration @ 0.050" : 219°
Maximum intake valve lift: 0.405" : 10.287 mm)
Exhaust duration @ 0.050" : 219°
Maximum exhaust valve lift: 0.405" : 10.287 mm

 

Seems like DFZ cam has less exhaust lift and just a little bit longer duration , compared to stock turbo RGX cam , but it has both more intake lift and duration . 

 

But how much overlap does the DFZ cam have ? any ideas ? 

And what might be expected in terms of rev range/power band with that one ? 

 

 

 

[petert 641]

I think you're picking hairs. I'm not sure of the DFZ centrelines off-hand but it is a very tame cam, designed to minimise emissions. I'd suggest the only difference between the DFZ and RFX cams is overall lift, which has zero effect on overlap, as they both have the same duration @ 0.050". I would run the RFX cam before the DFZ cam.

Edited Tuesday at 05:54 AM by petert

[DamirGTI 364]

I see .. Im not much of the cam expert tbh , lift and duration is what I understand and mostly that's about it with regards to that . 

 

I've driven one 2.0T engine but only briefly and ages ago , thus i really don't know how it performs in real when pushed to the limit .. and that one was conversion made in a 205 , mine is a 406 . 

 

And as said , engine needs running in first , and i need to redo and re-adjust the LPG system ... thus i fear that the RFX cam might mess up the fueling making it run lean , LPG side i can tweak as desired , OE petrol ECU certainly not !

Im unsure if the stock ECU maps can keep up with the more lift/duration cam , head is ported as well .

Speed density systems , not so great for such stuff but it is what it is .

Edited Tuesday at 12:33 PM by DamirGTI

[SRDT 253]

DFZ cams changed since 05/1992 so first you can check if all of yours are identical. This cam started on the very first XU9 the XU9S and was retained by the XU92C, XU9J1, XU92C+ and even the XU9M.

This is not a performance cam, the 110hp XU9M is the most powerfull of them all.

[petert 641]

I had a look through my notes. DFZ cam (circa '87-89) has 112º centrelines, so very tame on overlap and unlikely to cause you any tuning issues. RFX has 110º centrelines, so slightly more overlap, but seriously, still a very tame cam grind.

Edited yesterday at 03:52 AM by petert

[SRDT 253]

Here is your XU9S/XU92C/XU9J1/XU9M diagram:

 

[petert 641]

That diagram would suggest even milder 113.5º inlet and 115º exhaust centrelines.

[DamirGTI 364]

Oh , i need to figure out how to read that diagram !! 

I understand what it says in French but , is it crank or cam rotation ?

 

So closer lobe centrelines = more overlap , and more spread apart = less ? 

 

I think i've seen also something around 10.3mm inlet and 9.7mm exhsust lift for DFZ cam too .. not sure if that's correct or not .

Will check what i have but i think all of them are pre '92 DFZ cams .

 

If the ECU will be able to correct fueling for the RFX cam id fit it now , also unsure how much it'll shift the fuel consumption .

As standard it is a bit of a petrol guzzler , mostly cause of the 8v head Id say , shame they didnt use 16v head if even a mild one from XU10J4 RFV .

 

All of the three turbo cams seems to be the same lift wise , with some +/- 0.10-0.20mm for slight lobe wear .. not sure about lobe separation . 

Only early turbo RGY cam looks little bit different , with "full circle" opposite the lobe nose

Edited 8 hours ago by DamirGTI

[SRDT 253]

I can't find the same diagram for the XU10J2Z cam but I have the values :

AOA 1 °
RFA 44°
AOE 40°
RFE 5°

 

And the same for the XU9J1 cam :

AOA -3° (ROA 3°)
RFA 46°
AOE 40°
RFE 2°

[DamirGTI 364]

So seems like about 6deg of overlap on RFX , and zero aka none overlap on DFZ right ? 

 

[SRDT 253]

Yep no overlap, for reference here is the early non cat XU10J2 R6A with 7° overlap :

 

[DamirGTI 364]

I see ... thanks !

 

Anyhow , seems like the only way to find out how will it drive with each different cam , and if the ECU will cope , is by trying each after the stock cam . 

 

As I really have no clue what to compare to , only rough estimate .

 

Will start with with stock cam first , do the engine running in and needed adjustment/checks , then swap the cam .

I have WB sensor with the gauge installed , so will see what happenes .