Swapping Nissan L6 Cams?

[Tony D]

"I was looking at delta cams since Isky doesn't list a cam profile that will work with the stock springs. "

 

At Isky Cams for a meeting with Ron Iskendarian last April:

Frank280ZX: "Well, Ron, (opening catalog to the Datsun Section) which of these cams do you recommend for my build?"

Ron I: "Oh, those? Those aren't all we make, those are just for the guys who want to pick something out of a catalog and spend money. We have LOTS more grinds we can do! We have things MUCH bigger... Do you mind cutting your pistons?"

 

Point being, EVERY build is a CUSTOM BUILD. The SAME car, with an overbored 3.0 will get a different grind than a 2.8 or with a 3.0 that is Stroked but not bored. It's THAT precise these days. Spend a couple of hours talking to Ron on why things are done the way they are, and why you want a specific valve opening event and your head can start to hurt from the things that get poured out.

 

Call Ron, talk with him and tell him EXACTLY what you have and what you are building. Look at their cam specification sheet in the catalog online and have the answers to each of those questions ready when you talk to them. Things like bore, stroke, valve sizes, when you expect boost to come on and how much, HAVE PORT FLOW FOR THE HEAD READY with lift figures if possible. YOU WILL HAVE TO MAKE DECISIONS. Give him your concerns about using stock springs alone and that  you want something that will maximize performance at 460" valve lift, with a power peak around 6500 and redline at 7000/7200. Keep in mind the ITS guys measure stock valvespring life in HOURS.... for each excursion over X rpms they start the clock ticking and replace them regularly. Which I suspect is why Isky's minimum grinds go JUST OVER stock spring capability. You have to put in a set of their springs which are better at elevated rpms, and last longer-term than stockers which get weak and either break or loose tension leading to other issues... Yeah you can swap stock for stock. But as discussed, that's really just a stroking. Really, the cost for the springs and lash pads opens up MUCH larger cam possibilities when used with lower valve seals. By changing springs, retainers and seals the limitation of 460" lift is GONE and you can start to REALLY breathe, or at least leave it open to putting a larger cam in as you get more greedy with time...

 

You likely will get a cam quoted that is NOT in the catalog, won't cost you ANY MORE than one in the catalog, and will perform to what YOU wanted. Not just 'something from a catalog for guys who want to pick something out and pay their money."

 

Chances are the cam you have ground will appeal to many other people, so the cam specs will start being used by more and more people....maybe it starts  to get added to the next edition of the catalog...

[osirus9]

haha, now I know why JeffP says that all his conversations with you cost him lots of money Tony.

 

I do remember that scene from Tommy Boy. I get why MSA wouldn't offer a warranty unless they knew the whole valvetrain was brand new. I'd probably do the same thing if I were them, and I wasn't expecting a warranty, I was just wondering what exactly was necessary, and what was them just covering their asses. Looks like its mostly just a really good idea to rebuild/replace the whole damn head/valvetrain if you don't have a complete stock valvetrain to use (which I don't unless I were to just reuse my N47 head, but where's the fun in that?).

 

I'll do some more research and read through my "how to modify your datsun" book some more to try and come up with good figures to quote to Isky when I call them. 

 

Originally my goal of 325 rwhp was because of the limitations of the stock head and cam, but if I end up getting a much better flowing turbo cam with a matching valvetrain I feel like I should set my goal a bit higher and then run lower boost if I want to resist the urge to drive too fast. Maybe 375... And that would stick me exaclty in with Koryu in his turbo sizing thread... so probably shoot for a GT35R running like 17psi. I just hope a senza intake and a bigger cam, plus a valve angle job and intake/exhaust port matching will improve my flow enough to get away from the surge line. I'm thinking it will.

 

At least my bottom end will be ok to leave stock.. haha

[Tony D]

"I was just wondering what exactly was necessary"

 

That is a personal decision based on your pocketbook depth, and your willingness to gamble.

 

"Originally my goal of 325 rwhp was because of the limitations of the stock head and cam, "

 

I would say more aptly it was based on lack of in-depth research. Anybody reading my threads knows 350 on a stock head and cam since 1985 without a hitch, fart, or burble in well over 60,000 miles of driving and the compression on the engine continues to remain steady if not increase! (Stuck Rings after almost three years in outdoor storage.)

 

Everybody who does it knows: The Power is in The Head. The Corky Bell Phenomenon tried to convince otherwise....but the complications of the "Maximum Boost Mindset" wreck so many engines (just look at the archives here!) it's not even funny.

 

FLOW is the key, as boost is simply a manifestation of restriction to flow, nothing more. JeffP's engine made 380ft-lbs at 8.39psi of boost and 4,500 rpms. Think about that if you will....

 

What is your turbo discharge temperature at that point? Do you need an intercooler? If you had one, couldn't you possibly make that same power on STRAIGHT 87 OCTANE PUMP GAS?

 

What if you added a squirt of methanol now? For argument's sake WITHOUT an intercooler using a two-stage boost controller with say 10psi as base, and 17 or 20 psi as a 'scramble' setting?

 

In all the years of driving my turbo car I realized that for all the money I spent on that state of the art 'adjust from your seat' boost controller....I only ever used two settings "10 psi, or CorvetteEating" Nothing in between. Continuously progressive boost control was not needed in my case. It was either driving normally, or hammering it.

 

With a head that flows, that would mean low setting to be somewhere in the 325-350 range (ON 87 OCTANE NO INTERCOOLER) and maybe closer to 425-450 on 'high boost'....

 

Cogitate on that scenario. BOTH can be done on bone stock bottom ends. One day I will get around to replacing my con rod bolts with ARPs but they are the stock units for now.