Nissan/Datsun L4 project

[KnightEngines]

The roller lifter cuts down on the surface area used on the follower - like going from a larger dia flat lifter to a smaller one, it limits the intensity of the lobes quite a lot more than you'd think.
I haven't seen a roller finger follower than offers any more lift/intensity than a sliding contact follower - especially if you use a reduced base circle on the sliding follower cam.
In these things lift is king, you cannot get an overly large valve in there - relatively small bore for the capacity, you have to make it up in throat & lift.

There is no way it takes 75hp to turn an L28 cam, reduction in friction may be worth 10hp or so, which will probably be lost by reduced lobe intensity.

[hoffman900]

Tony, i've been looking at another application and I am realizing the same thing.

[KnightEngines]

Yeah, "roller is always better" simply isn't true.
Sliding finger followers can be pretty damn good.

[KnightEngines]

Well, after a long lay off while the rest of the car got built around the engine I'm getting this ready to dyno finally.

Got most of the details sorted, just waiting on carb linkage kit, jets & soft mounts, a couple of little ignition parts & a free dyno slot - should be making noise within a couple of weeks.

[4vpc]

I'm wondering if you're a fan of Photobuckets new rules...

[KnightEngines]

Meh, I gave up on photobucket a while back, I'll upload some fresh pics some time soon.

[KnightEngines]

So we spent 2 days beating the hell out of this on the dyno & still don't know exactly how much power it's making!

It's a fussy little prick of a thing, IR 4 cylinders don't seem to get along with large Stuska dyno's (dyno is 2000hp capable & is Depac controlled), we couldn't load it properly to do a full sweep, by the time we unloaded the dyno enough that it was happy to pull from 4500rpm & pull through an out of tune harmonic at 5800rpm it'd run away in the top end, when we loaded it enough to hold the top end we couldn't pull it below 6500rpm.
Every time we made a change to cam timing, ram tube length or collector length we had to do a few pulls to figure out how to load it & get some data for most of the rpm band.
In the end after 40-50 pulls (not even an exaggeration) we got a decent tune in it, plugs look real nice, AFR's are good right through etc but we don't really know what sort of HP it's making as dyno load at high rpm was very, very finicky & we never found the "fine line" to properly load it up top.
In the car those issues won't exist - dyno operator has had grumpy little speedway midget engines do the same thing (IR mech injected 4 cylinders), went through the same laborious process to tune the damn things & despite being right pricks on the dyno they were rockets in the car.

Best we can figure it's making somewhere between 235-255hp & holds power out to at least 7800rpm (which was a surprise, previous 2L engine fell over above 7200rpm, but was experiencing a little valve float, which is now fixed), we do know that it's making 209ft/lbs at 5500rpm - we could load it properly from 4500-5500.
It makes usable power from 4000-8000rpm, which is a real wide power band for a little highly strung engine.

So in the end I'm happy with the engine but a little frustrated/disappointed that I don't have a proper dyno sheet to show the world.
I'll just have to report on race results instead!

[cjperformance]

Thats doin well. That Datto should get moving nicely now.