Tighe Cams/RPW:

Version:.......................6G74...Ralliart...S tage1...Stage2...Stage3

Intake Open BTDC..........15......13.........16.........24.... .....24
Close ABDC...................53......55.........60...... ...62.........62

Exhaust Open BBDC........53......51.........60.........60...... ...62
Close ATDC...................15......17.........16...... ...16.........24

Overlap........................30......30......... 32.........40.........48

Intake Duration..............248....248.......252........ 262.......262
Exhaust Duration............248....248.......252........25 2.......262

Lift:.............................?

I'm a NooB to cams like most people here. I just came across this info. I rely on more experienced operators to interpret it for now.

Going by the specs youu have post mate, my cams have more duration than stage 3 RPW's. Mine have 268deg intake and 262deg exhaust. :shock: And 343" lift intake and 325"lift exhaust.

That's why your doing a 14sec quarter! :D

Btw, do people really think RPW make these cams?

Going by the specs youu have post mate, my cams have more duration than stage 3 RPW's. Mine have 268deg intake and 262deg exhaust. :shock: And 343" lift intake and 325"lift exhaust.
Hey Jason, where did you get your cams from and who made them?

Hey Jason, where did you get your cams from and who made them?

They were made at MMAL when i was there and the first set made were used as trial for a higher output ralliart motor that got knocked back by management and the second set were ground up for me but were made with more duration as i requested.
They need at least 10.1 compression to work reasonably.

What was the philosophy behind knocking this back?!?!

What was the philosophy behind knocking this back?!?!

They didnt like the slightly lumpy idle and they found it too hard to get it to meet idle emissions and make high power (remember they were on a limited budget)
The other main issue is they wanted the ralliart to run on standard ULP and for theses cams to work reasonably well they need at least 10.1. If only the TE-TW 3.0/3.5L had a knock sensor.

Now THIS is the information ppl should be concerned with ;)

good stuff mate!!

Nice one EZ Boy. This is going in the FAQ.. at least until I get a cease and desist order ;)

Edit: Added to the FAQ in a pretty table (http://www.wermspowke.net/wiki/index.php/Engine#Camshaft_Specifications)

Edit again: How good is this page (http://www.aperaceparts.com/tech/camterminology.html) (for noobs like me.)

Question: If RPW's S1 cams open the inlet valve at 16deg BTDC and close at 60deg ABDC, doesn't that mean the inlet duration is 256 degrees (16 + 180 + 60) rather than 252 degrees as you've said? Likewise S2 and S3 would be 266 inlet duration?

Duration is normally measured from and to a point when the valve is open a nominated amount (normally .050") not from when it opens or closes. This could be the case here.

Version: 6G74 Ralliart Stage1 Stage2 Stage3

Intake Open BTDC 15 13 16 24 24
Close ABDC 53 55 60 62 62

Exhaust Open BBDC 53 51 60 60 62
Close ATDC 15 17 16 16 24

Overlap 30 30 32 40 48

Intake Duration 248 248 252 262 262
Exhaust Duration 248 248 252 252 262


im sure 99% of us dont understand these figures but are to ascared to ask, can anyone put these into practical terms ?

im sure 99% of us dont understand these figures but are to ascared to ask, can anyone put these into practical terms ?
As I posted further up.. check out this glossary (http://www.aperaceparts.com/tech/camterminology.html).

OOoOOoo awsome saved to favourites :P

Excellent stuff!!!!! Exactly what I needed. Ahh, my fingers are itchy.....



Edit: Added to the FAQ in a pretty table (http://www.wermspowke.net/wiki/index.php/Engine#Camshaft_Specifications)
Edit again: How good is this page (http://www.aperaceparts.com/tech/camterminology.html) (for noobs like me.)

Duration is normally measured from and to a point when the valve is open a nominated amount (normally .050") not from when it opens or closes. This could be the case here.
That much I knew, but wouldn't you either quote duration in terms of the cam lobes or in terms of duration at 50 thou and expect them to be considerably different?

For example, I spoke to Dallas who tells me the new cams he's had ground have 262 degrees duration on the inlet valve, which apparently resolves to more like 222 degrees duration at .050".

If you wanted crow to make some cams do you only need the information provided by EZ boy(duration etc.), is that it?

That much I knew, but wouldn't you either quote duration in terms of the cam lobes or in terms of duration at 50 thou and expect them to be considerably different? Yes, most manufacturers do use "duration at 50 thou", but when the specs quote "valve opens at xx BTDC and closes at xx ABDC" you can't convert that to "duration at 50 thou" without knowing the ramp rate (how quickly the valve opens).

For example, an old OHV motor would open valves slowly, so the "opens at" to the "closes at" figure would be a lot larger than the at .050" figure. But, a modern, say Top Fuel, motor would open the valves VERY quickly so it's "opens at" to the "closes at" figure would be a lot closer to the at .050" figure.

Make any sense? ..... 'Cause I think I confused myself. :confused:

Make any sense? ..... 'Cause I think I confused myself. :confused:
Perfect sense. Cheers :cool:

how do you calculate lift?

whats the unit on these numbers? degrees?

I am all confused. Expect a lot of questions from me...lol

how do you calculate lift?

whats the unit on these numbers? degrees?

I am all confused. Expect a lot of questions from me...lol
You can't calculate lift from those numbers.

And yeah, duration, overlap and valve opening points are in degrees.

You can't calculate lift from those numbers.

And yeah, duration, overlap and valve opening points are in degrees.

ok duration is how many degrees the valve opens then?


What does overlap and valve open points mean?

ok duration is how many degrees the valve opens then?
Pretty much, yeah.. those duration numbers are from when the cam lobe 'begins' until it ends. The duration that RichardM was explaining is a different number that describes how long the valve is more than 0.050" (50 thousands of an inch) from its seat.



What does overlap and valve open points mean?
Overlap is the length of the arc during which the inlet and exhaust valves are open at the same time.

And the valve open points.. well an intake open at 15 degrees before top dead centre tells you when the intake valve starts to open, then it's open for whatever the intake valve duration is, then it is fully closed at 53 degrees after bottom dead centre.

This of course assumes you know what TDC and BDC are too :D

Pretty much, yeah.. those duration numbers are from when the cam lobe 'begins' until it ends. The duration that RichardM was explaining is a different number that describes how long the valve is more than 0.050" (50 thousands of an inch) from its seat.



Overlap is the length of the arc during which the inlet and exhaust valves are open at the same time.

And the valve open points.. well an intake open at 15 degrees before top dead centre tells you when the intake valve starts to open, then it's open for whatever the intake valve duration is, then it is fully closed at 53 degrees after bottom dead centre.

This of course assumes you know what TDC and BDC are too :D

Yeah thanks...I know what TDC and BDC is at least. I got it 15 degrees on the intake valves means thats when it starts opening. Then how long its open is the valve duration. Then its closed at 53 degrees BDC.

Overlap is when both valves are open at the same time. Got it. thanks