IceY2K1

iTrader: (3)

Have you looked into these VTC pulleys?

http://www.z1auto.com/prodmore.asp?m...ine&prodid=922



I'm *STILL* trying to figure out what these guys claim of "increase overall cam advance to 55 degrees (15 degrees longer than stock)" means exactly.

SR20DEN?

Jeff92se

iTrader: (82)

It means the range of adjustability is 15 deg wider than before. For a total of +/- 55 degrees. Which is pretty far. But I don't know if it would really increase proformance or not. And I don't know if the ecu needs to be altered to take advantage of it. ie.. if the ecu is only programmed for 40 deg total adjustment, how would it deal with the 15 more total adjustment?

Also just because there is more adjustment, doesn't mean there is more hp to be had. Unless they already tested it to prove it. ie.... like moving the mevi opening point lower than 5,000 rpm. Does no good and actually hurts power.

And these aren't "cams". Only cam gears.

IceY2K1

iTrader: (3)

The variable intake valve opening range is 5ATDC-30BTDC, so 15-degrees more is only 50-degrees. Do you think the "overall cam advance" means it can vary the intake opening from 20ATDC-15BTDC or 45BTDC-10BTDC or both? And wouldn't that effect the intake valve closing?

Agreed, but it's NISMO and should make power(in theory).

I know that. I just ASSumed the only people that would consider installing these, would also be considering installing cams.

Jeff92se

iTrader: (82)

It's probably 7.5 deg more adjustment either way. Again, where's the ecu reprogram to account for it?

Umm these things are DESIGNED to affect the intake valve timing. What is your point?

Why would you ASSUME that someone would be doing cams? The cams don't require removal for install. At least on my VE30DE it doesn't.

IceY2K1

iTrader: (3)

It says professional tuning, so you may need to play with fuel/timing to benefit depending on how smart or dumb the CVTC system really is.

My understanding(could VERY well be wrong) is that this pulley can only cause the rotating of the cam to occur, so if the intake valve opens 15-degrees sooner, then it must close 15-degrees sooner, ie duration doesn't change, just opening and closing points.

Because you're removing the timing cover to install either and I don't see all that work is worth just installing VTC pulleys.

Jeff92se

iTrader: (82)

So I guess you have to near those guys.


You are right. But you didn't say that in your first question. Duration doesn't change. Duration is designed into the cam lobes as is lift.


Why not? That's not up to you to decide. Expecially when buying cams is a multi-thousand dollar purchase.

IceY2K1

iTrader: (3)

It's a NISMO part...doubt it.

Actually I did, just in FSM speak.

Again ASSumed from what I've seen...not a mind reader, but personally it isn't worth the labor involved just to install VTC pulleys to only get "increased engine response and a much faster rise in torque at lower rpms". Plus, VTCs might not play friendly with certain cam grinds or gains might be minimal with out NISMO cams. My bet.

Jeff92se

iTrader: (82)

Sorta ambigious statements. In your first statement, you didn't know if it affected the duration or not.

So I default to my orignal question of how is one going to take advantage of this w/o ecu tuning??

IceY2K1

iTrader: (3)

"15 degrees longer than stock" to me implies valve open time.

Again, it doesn't add up to 55-degrees either way. CVTC moving while the valve is open and before it closes could change...dynamic vs. static...I'm no VTC expert. It was in my question FSM opening and closing range, I modified it and it doesn't add up to 55-degrees, so the question was how.

As a NISMO part it could make power straight out of the box, ie typically factory replacement parts that add power, yet needs AFR tuning for max potential. The "15-degrees longer than stock" could be well within the stock ECUs limits.

SR20DEN

iTrader: (7)

Where did you get those numbers Ice? "5ATDC-30BTDC"




55º sounds right to me, the BMW E46 M3 Vanos sweeps 60º on the intake and about 4xsomthingº on the exhaust.
However the Z1auto site is FULL of misprints, typos and BAD information so take it with a grain of salt.

IceY2K1

iTrader: (3)

SAE tech doc...however the 2K2+ FSM shows 238-degrees duration on the intake vs. SAE tech doc 240, so a bit off.

SAE doc:
IVO 5ATDC-30BTDC<~~~~~ -6?? in FSM(VTC off)
IVC 65ABDC- 30ABDC<~~~64 in FSM(VTC off)
EVO 52BBDC<~~~~~~~same in FSM
EVC 8ADC<~~~~~~~~same in FSM

FSM:
Exhaust duration is 240-degrees.
Intake duration is 238-degrees(VTC off).

IceY2K1

iTrader: (3)

Here this is easier:

FSM VQ35 cam timing w/VTC OFF


SAE VQ35 cam timing