Nissan/Datsun L4 project
Moderator: Team
Re: Nissan/Datsun L4 project
That head needs some of these, I think...
Especially if you're going CNC masterless cam grinding...
Especially if you're going CNC masterless cam grinding...
-
- Member
- Posts: 120
- Joined: Sat Mar 27, 2010 9:31 pm
- Location: Aotearoa
Re: Nissan/Datsun L4 project
I'm not sold on that roller conversion. They have to be heavier than the stock slipper pad rockers. Smaller roller is a negative too, I don't think you would be able to run the same velocity as the stock slipper rocker. Reduced friction and ease of profile design (no oil entrainment to worry about) are about the only gains I can see, I'd be interested to hear others opinions.
TK is that crank trigger wheel aluminium? Has it got steel or magnet inserts?
TK is that crank trigger wheel aluminium? Has it got steel or magnet inserts?
WhitleyTune - Bespoke Camshaft, Valvetrain & Aluminium casting
-
- Pro
- Posts: 454
- Joined: Sat Jun 04, 2011 5:46 pm
- Location: Canada
Re: Nissan/Datsun L4 project
Very nice, thanks for posting
Are those flat top pistons? hard to tell due to reflections - -
Are those flat top pistons? hard to tell due to reflections - -
-
- Guru
- Posts: 2694
- Joined: Fri Jan 09, 2009 8:51 pm
- Location: Australia
Re: Nissan/Datsun L4 project
Yeah, I'm up in the air about roller finger followers, a customer has gotten hold of a roller cam & followers for a BMW M20 engine, working out the area under the curve it's no better than the old slider follower.
Yep, alloy, magnet inserts - it's an MSD universal kit, comes with all the bits & oversized brackets etc that you make fit.TK is that crank trigger wheel aluminium? Has it got steel or magnet inserts?
Yeah, crap photo - 7cc shallow dish with small valve reliefs.Are those flat top pistons? hard to tell due to reflections - -
-
- Guru
- Posts: 2694
- Joined: Fri Jan 09, 2009 8:51 pm
- Location: Australia
Re: Nissan/Datsun L4 project
All done, manifold just sitting on, can't bolt it up till dyno time - have to fit the headers at the same time.
Dyno is about a month away unfortunately.
Dyno is about a month away unfortunately.
Re: Nissan/Datsun L4 project
I noticed you've bolted the carbs to directly to the manifold. Every Datsun I remember with sidedrafts required some kind of vibration isolation for the carbs. The Datsun comp isolators for 50mm carbs were seemingly the most popular. Some people went to the trouble of removing 1/2 of the rubber between the isolator flanges to make them even more compliant. Last I knew the isolators were NLA though. I guess the next best would be aluminum plates and O-rings and cushions under the bolt heads.
-
- Pro
- Posts: 454
- Joined: Sat Jun 04, 2011 5:46 pm
- Location: Canada
Re: Nissan/Datsun L4 project
Tony, some quick calcs suggest the following; pls confirm
89mm bore x 92mm stroke gives 2290cc swept volume
6.5" rod equals 165.1mm, therefore 1.79 to 1 rod/stroke ratio
Don't know pin diam or block height so cannot calc piston compression height, crown thickness, or ring pack height - -
If the compression is 13.2 to 1 with 7cc dished pistons at zero deck and a 1mm head gasket, chamber volume must be around 36cc?
Would you have preferred a flat top piston and say 43cc chamber, but broadening the chamber and/or sinking the valves was impractical?
Beautiful handwork, progressive and effective mods, thanks again for posting
Hope someone produces the cam you deserve - -
89mm bore x 92mm stroke gives 2290cc swept volume
6.5" rod equals 165.1mm, therefore 1.79 to 1 rod/stroke ratio
Don't know pin diam or block height so cannot calc piston compression height, crown thickness, or ring pack height - -
If the compression is 13.2 to 1 with 7cc dished pistons at zero deck and a 1mm head gasket, chamber volume must be around 36cc?
Would you have preferred a flat top piston and say 43cc chamber, but broadening the chamber and/or sinking the valves was impractical?
Beautiful handwork, progressive and effective mods, thanks again for posting
Hope someone produces the cam you deserve - -
-
- Guru
- Posts: 2694
- Joined: Fri Jan 09, 2009 8:51 pm
- Location: Australia
Re: Nissan/Datsun L4 project
Just dummied up for pics, we've got insulators for them, won't be bolted directly to manifold - harmonics with the Z22 crank would 'boil' the fuel in the float bowls.I noticed you've bolted the carbs to directly to the manifold.
Tony, some quick calcs suggest the following; pls confirm
89mm bore x 92mm stroke gives 2290cc swept volume - yep
6.5" rod equals 165.1mm, therefore 1.79 to 1 rod/stroke ratio - 6.05" rod, 1.67 rod/stroke ratio
Don't know pin diam or block height so cannot calc piston compression height, crown thickness, or ring pack height - - comp height 1.13", fairly compact ring pack, no support rail required.
If the compression is 13.2 to 1 with 7cc dished pistons at zero deck and a 1mm head gasket, chamber volume must be around 36cc? - 34cc, .050" head gasket, +.010" deck height.
Would you have preferred a flat top piston and say 43cc chamber, but broadening the chamber and/or sinking the valves was impractical? - nope, small dish & compact chamber will make more power than larger chamber & flat top, not a lot in it, but it's real.
-
- Pro
- Posts: 454
- Joined: Sat Jun 04, 2011 5:46 pm
- Location: Canada
Re: Nissan/Datsun L4 project
I was no longer driving the car consciously. I was driving it by a kind of instinct, only I was in a different dimension.
West Siloam Dispensary
West Siloam Dispensary
Re: Nissan/Datsun L4 project
L20B block is 227.45mm tall.
The rollers are 0.800" diameter in my finger followers, the valve tip roller is 0.375" diameter. They are only 4 grams heavier than the stock followers. The sliding friction is the enemy here, not so much the cam profile. The finger followers I posted above are from AU, WES engines.
It takes ~75HP to turn the L28 6-cylinder camshaft at 5000RPM, all stock springs and cam profile. With the roller followers, that gets cut down by a LOT. Free HP right there. ~25HP gain, right off the top, but it's hard to make accurate comparisons due to the differing cam profile and springs. Not so much that the roller cam was a big performance grind, but that it certainly wasn't optimized. Straight copied a Mitsubishi cam profile from a 4G63 SOHC.
And, no hunting around for oil that's harder and harder to find these days-Any quality synthetic will do.
The rollers are 0.800" diameter in my finger followers, the valve tip roller is 0.375" diameter. They are only 4 grams heavier than the stock followers. The sliding friction is the enemy here, not so much the cam profile. The finger followers I posted above are from AU, WES engines.
It takes ~75HP to turn the L28 6-cylinder camshaft at 5000RPM, all stock springs and cam profile. With the roller followers, that gets cut down by a LOT. Free HP right there. ~25HP gain, right off the top, but it's hard to make accurate comparisons due to the differing cam profile and springs. Not so much that the roller cam was a big performance grind, but that it certainly wasn't optimized. Straight copied a Mitsubishi cam profile from a 4G63 SOHC.
And, no hunting around for oil that's harder and harder to find these days-Any quality synthetic will do.
-
- Member
- Posts: 120
- Joined: Sat Mar 27, 2010 9:31 pm
- Location: Aotearoa
Re: Nissan/Datsun L4 project
Do you have any evidence to backup your claim that it takes 75hp to spin the L6 valvetrain at 5000? Seems excessive to me. I have yet to put one on a Spintron but the biggest one they make is 75hp!
Valvetrain friction is more an issue at low rpm - hence why all the modern motors are roller now, it helps with emissions and economy. I believe most top end high rpm race motors are still slipper pad finger followers.
I'd agree going roller is a good idea for a street motor, it is a lot of money though - aren't those WES rockers something like $250 each?
Valvetrain friction is more an issue at low rpm - hence why all the modern motors are roller now, it helps with emissions and economy. I believe most top end high rpm race motors are still slipper pad finger followers.
I'd agree going roller is a good idea for a street motor, it is a lot of money though - aren't those WES rockers something like $250 each?
WhitleyTune - Bespoke Camshaft, Valvetrain & Aluminium casting
-
- Guru
- Posts: 2694
- Joined: Fri Jan 09, 2009 8:51 pm
- Location: Australia