Can I use stock cams in an N1 block?

[msammut]

Can I use stock cams in an N1 block?

Gentlemen and ladies

I have an RB26 N1 block and I have stripped down my stock RB26 block.

I would like to build this block as an N1 engine. I am getting my crank blue printed. N1 oil pump and N1 water pump.

Are the N1 cams the same as the stock ones?

i read this on this site. 

SKYPER

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Posted March 31, 2008 · Report post

N1 cams have the same lift, duration as stock GTR cams but the central angles are different -

http://www.tomei-p.co.jp/_2003web-catalogu...haft-specs.html

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Can anyone clarify?

thank you.

[KiwiRS4T]

According to the Tomei chart (as you know) all RB26 cams are the same.

But according to Wikpedia:  . The N1 engine also has upgraded camshafts and upgraded turbochargers.

Hopefully someone with such an engine will enlighten you.

What are you going to use the car for? You may want to think twice before using the N1 water pump.

[r32-25t]

And probably the n1 oil pump due to them breaking a lot

[HarrisRacing]

***** EDIT. Observe strikethroughs below. I proved this incorrect later with an EXTENSIVE dyno session. My car LOVES overlap on powerband. Was able to go 6deg intake advance and 4 deg exhaust retard (CRANK DEGREES...NOT CAM), and the car picked up BIG power in midrange. It does, unfortunately, sound like a cammed out racecar at idle now :).

*************************************************************

 

From what I've read the only changes that Nissan made on the N1 cams are the timing...not with the actual profile. They moved the exhaust cam retarded 5 degree which makes for 5 deg of overlap vs. the factory set 0 for non-N1 cars..but they did this on the cam and not with the gear. So in a sense everyone has N1 cams if you buy an exhaust cam gear and retard it 5 deg at the crank (or 2.5 on the cam).

If you think about it, I think this alone is likely where everyone gets the idea of the cam timing set at "-4 EX, +2 IN" which puts your overlap at 6 deg...when the N1 was 5 deg overlap (all done with the exhaust cam) from the factory. 6 one, half-dozen the other.

But when you add aftermarket cams, I found that going further on overlap started hurting my car's power. For example, my Tomei Poncam A's are 31 deg overlap when set at 0,0. When I tried the typical "-4 EX, +2 IN" It was too aggressive in the mid range and started losing on top. I'm currently at 0, 0 with Tomei Poncam A's. With factory I would have induced some overlap like most people do though. I'm shortly going to hit the dyno and try to advance the exhaust cam to go LESS overlap which should make for a smoother idling car and more power on top end (<---THIS MADE LESS TQ BUT SIMILAR POWER - WAS BETTER POWERBAND WITH OVERLAP!). But really I see no reason to ever be 0 overlap on such a high-revving engine.

I have attached a screenshot of my excel spreadsheet for looking at cam timing changes w/ respect to overall valve opening and closing as well as the spreadsheet.

Cam timing overlap changes.xlsx

[msammut]

Thank you all for enlightening me.

I have read the N1 engine was specifically built for racing and that the oil pump on the N1 was a higher flow type. Not much about the N1 water pump though. I will not be racing the car. I just want a reliable strong engine as I got the block fairly cheap.

Are the oil pumps prone to failures?

So is the consensus that I can drop the cams from the stock block into the N1?

If I change the cam timing as suggested above to match the N1 what will be the likely effect?

Thank you all again.

[HarrisRacing]

I've read the N1 oil pump is better...but I can't confirm. I was not convinced enough to go with it and instead went with Tomei $$$$$$$$.

The N1 water pump just works better at high rpms...not necessarily for a streetcar, but I am running it on my streetcar which sees 8250 rpms every time I drive it and I live in a very hot climate with no issues on the KOYO radiator. It reduces cavitation at very high rpms.

Factory or N1 Cams should work no problem in your motor, just get your shims correct for valve clearance to make sure you are not losing power and are not going to hurt the motor.

Indexing the cams closer together (cam gears move AWAY from each other, but CAMS move toward each other increase the valve overlap which means as the piston is pushing exhaust up out of the cylinder through the exhaust valve, the intake valve will start to open slightly before the exhaust valve is closed...

This results in a few things:
1) At lower rpms the car will run slightly rougher and have slightly less vacuum because you are diluting (slightly) the exhaust and intake streams.
2) At midrange rpms where the exhaust back pressure in the turbine is less than boost pressure, the car will make more torque and power. This will make for a "punchier" feeling car.
3) At high rpms when the turbine starts to make more backpressure than the boost pressure the exhaust will reduce the ability of the intake to inject boost into the cylinder. This means that you will lose some top end power at high end.

So basically when you move the CAMS closer together by increasing how much the valve timing overlaps, (by either retarding exhaust cam or advancing intake cam) you "tighten" the powerband, but you make it more torquey. When you move the CAMS further apart you make the car run smoother around town, and make more power on top end, but it will not be as agressive in the mid-range. I think the N1 setup was for the N1 turbos, and for road racing. They were probably increasing mid-range response because this is what you need in road course racing to pull out of turns.

Yes I think if you retard the exhaust cam 5 degrees on stock cams, you essentially turn them into R33 N1 cam timing.

[r32-25t]

Yes the n1 pump flows more then the standard gtr pump, yes they are common to break due to the brittle material used for the gears inside 

[KiwiRS4T]

There was I believe a run of bad N1 pumps. Some people won't touch them but I have done about 20.000km on one. If I were building a high spec high power high revving engine I would use a Tomei.

The N1 water pump is designed to be efficent at high revs so probably not a good idea in a street car and certainly not better than a new stock pump.

If you are putting stock cams in your engine you could put adjustable gears on both and get them tuned on a dyno for best results.

 

[msammut]

Thank you all again for your experieced comments and insights.

I will get the N1 stuff. And i will will be getting the shims checked.

Michael

[GTR-N1]

N1 turbos are laggy which is why the timing of the cams assists bottom end power and torque. As stated above, the top end of the curve flattens a bit earlier.

There's no need for a street car to have a N1 water pump. Save your money. Impeller blades are fewer on the N1 and larger in size. As stated above, they're only more efficient whilst racing.

The N1 oil pump is more efficient than stock but not as robust as some others.