Type b pon cams for 25 neo

[lcxu105]

Has anyone got a full cam specs of the 25 neo type b pon cams. 

Inlet and exhaust open and close. 

I know that they are 260 9.15 but want the rest of the cam specs. 

Thanks in advance

[Manuel Kasko]

Does this give the info?

I know nothing about them but did a google and found this. 

 

http://www.tomeiusa.com/_2003web-catalogue/e072_cam_RB25.html#pro

[lcxu105]

No.

Want to know what the specs are for inlet open before tdc when it closes and same for exhaust for bdc.

[GTSBoy]

It'll be within a few degrees of the plain R33 256s posted in the other thread.

[lcxu105]

7 hours ago, GTSBoy said:

It'll be within a few degrees of the plain R33 256s posted in the other thread.

What other thread?

Also if it's not the type b neo cams then there is no point in it as it's not the correct information and assuming that it is makes it easy to have a stuff up degreein in the cams. 

[GTSBoy]

2 hours ago, lcxu105 said:

What other thread?

Also if it's not the type b neo cams then there is no point in it as it's not the correct information and assuming that it is makes it easy to have a stuff up degreein in the cams. 

Really?  It was like 3 places away from this thread at the time you posted your response.

And seeing as they are very nearly the same cam for very nearly the same motor, I stick by my statement that they will be within a few degrees.

And when you say "degreeing the cam", I assume you mean putting a degree wheel on the front of the motor and setting up a dial indicator so you can find out for yourself when the valve events are.  That's what I would do.  In which case you don't even need to know the answer to your question except as guidance to approximately when to be paying attention closely to the wheel and gauge.

[lcxu105]

You need to know when its supposed to open and at what duration 10 40 50 thou and when it closes to dial cam in to optimum settings. 

Within a few degrees is not optimum settings

[lcxu105]

Found it.

For anyone else who might want it

[discopotato03]

Search Tomei USA Cam Cards . On this computer Internet Explorer fails so try Firefox instead .

 

R34 GTt Type A 252/9.15 lift cams . 4-68 59-13 on 120 and 115 deg (in/ex) lobe centers . Overlap 4+13=17 degrees .

R34 GTt Type B 260/9.15 lift cams . 8-72 63-13 on 120 and 115 deg (in/ex) lobe centres . Overlap 8+13=21 degrees .

Personally all I think you learn from measuring duration with the valves off the seats is how fast or "aggressive" if you like the valves open and close initially . Obviously rapidly increasing the lifting and seating at these points would indicate "steep" lifting and closing ramps on the lobes . If you search Tomei USA Cam Cards they give effective durations at closed and a few clearance levels .

Too busy atm but later I'll compare the R33 hydraulic and R34 shim/bucket durations at the given seated and clearance points mainly because I want to see what Nissan achieved ramp wise with the R34s "soild" buckets . We know they went to higher lifts with from memory shorter durations on the later system and that is the way to breathe without long durations and extended overlap from the end of one cycle to the beginning of the next .

 

Later cheers A .    

[lcxu105]

By setting up the cam at the correct degrees to the cam card specs you get the full effects of the cam and power from the up grade. 

I know people normal just play with it on the dyno but if you set it up correctly before you put the car on the dyno there is no reason to adjust the cams on the dyno other than to bring on boost earlier or move the peak hp in the rev range. 

[GTSBoy]

Or you could use a dial indicator and educate yourself instead of relying on the cam card.  If you're going to the effort to put a degree wheel on the engine you're already most of the way there in terms of what you have to do.  You could do the whole thing without up-front knowing a SINGLE thing about the cams you're fitting.

I mapped out the profiles on several Alfa Romeo cams in my (Afla 2.0) engine by hand back in the 90s and it was a good way to spend an afternoon.

[discopotato03]

I've been trying to find the R34GTt Nissan engine manual to get the standard cam timing numbers , does anyone have a working link to the Neo 25 WSM .

 

Cheers  A . 

[discopotato03]

I'm trying to work the 25T Neo valve timing from Tomeis duration and lobe centre numbers . Works out

236/232 durations and 119/115 lobe centers . In theory the inlet duration halved minus the lobe centre angle should equal the inlet opening time ie 236 halved is 118 - 119 = -1 . Duration is 236 so 236 - 180 = 56 . 56 - 1 = 55 so inlet timing must be 1-55 .

Exhaust 232 x 0.5 = 116 . 116 - 115(lobe centre angle) = 1 degree before top dead centre so exhaust valve timing looks like 52-1

overall 1-55 52-1 . 

Overlap 2 degrees ?

Does anyone know how many degrees the inlet cam moves on the hydraulic actuator ?

 

Edited August 3, 2016 by discopotato03