First, let me start off by saying, no, I haven't left the 720 scene. Not by a long shot. I have been very active on the Nissan 720 Owners Facebook page, and that's mostly from convenience. Logging in and getting over to here has been uncommon in recent years.
That said, I have been working hard to keep all of my projects running. My '82 King Cab has been running well and I even splurged on some nice tires and the 80-82 style 4x4 stripes. Mike Cieply in Oregon set me up with some 4x4 fender flares as well.
When I last posted, I was working on a Z22E motor for it. Thankfully, it runs well and has been i n service for about 20,000 miles with no major issues.
The engine is a Z22 block bored 0.020" (0.5mm) over with Federal Mogul brand cast pistons, topped off with a W04 Z20 (MPG) 43cc cylinder head and a 274/274 Crower cam that had to have been ground some time in the 80s. The usage of the MPG head on the Z22 block pushed my compression to roughly 9.8:1. That kind of compression has really made this motor feel much better than the average NAPS-Z.
The exhaust manifold is a stock Z24 manifold from an '85-86, followed by a 2 1/2" exhaust. The intake is a stock 1982-83 200SX manifold bored open to accommodate a 60mm KA24E throttle body from a 240SX.
Initially, I ran the motor on a 240SX KA24E ECU and wiring harness, which did work, but i had a difficult time getting to tune correctly. In the end, I installed a Haltech E8 standalone and harness, which simplified the tuning process tremendously. In the process of tuning, I paid to put the truck on a dynanometer and for someone to correctly map the fuel and ignition tables. At the end of the dyno session, the truck was putting 102 hp to the wheels. Torque was 95 ft-lbs to the wheels beginning at 1800 rpm and stayed close to that number up to about 4300 rpm.
Doesn't sound impressive, right? I know. But those are at the wheels. Nissan rated the motor NET horsepower at the crank and made 102hp @4000 and 117 ft-lbs torque at 1800 rpm. If I were to be fair, I estimate a 30% drivetrain loss, so this motor is about 133hp and 130+ ft-lbs torque, which puts it close to the KA24E in overall power and kills it in overall usable torque.
Admittedly, I'm not a huge fan of the KA24E after my personal experiences. That said, I'm proud to have built for myself a NAPS-Z motor I can be proud of which proves a belief I had that the motor is capable of more than it is given credit for.
[pictured above; my 1982 720 with my 1972 Datsun 1200 at the 6th Annual Multi-State Datsun Classic in Williams, AZ. The 1200 tied for 1st in the "Modified" category. The 720 placed 4th overall in the "truck" category behind 3 620 trucks.]
So, there you have it. I have been away a long time, and I'm checking in. Who knows how long this place will be around, but you can catch me at my e-mail firstname.lastname@example.org or on Facebook on the Nissan 720 Owners page.
Hey Patrick good to hear from you. In the last 4-5 years I gave my 620 away but pulled the Z24 and 5 speed out. Driving my '76 710 goon that's from Nevada. Good to see the 720 again and hear about it. 103 RWHP is impressive and the NAPS is so underappreciated. What's in the 1200?
I was thinking... your numbers are coming from the shorter stroke z22.... that is pretty darn good. I wonder what you would achieve by adding a z24 crank.
I think part of it has to do with the high compression. The other has to do with the moderate cam I'm running. Certainly the larger bore and stroke of the Z24 as well as the larger intake ports of the Z24 should on paper allow for more power.
That said, you're gonna absolutely hate the next motor I'm building right now for a different truck. I'm building a Z24/KA hybrid. On the surface it seems foolish, but with the Z24 block, no custom pan or mounts are required, the Z20 single plug distributor pickup will work with a megasquirt 2 as a crank reference, the KA truck head I have has improved air flow over the Z24, the KA truck intake I have uses long runners which will help torque out and by using a Z24 bottom end, I can run the more reliable dual-row timing chain. I'm well aware of the fact that this has been done in a different form before by someone on Ratsun, but I'm going to keep this much more uncomplicated than he built his.
The Z24 crank won't drop into the Z22 block without cutting down the counterweights and block etc.etc. But the Z24 engine is complete and ready to go. Hell they were 130 torque at 2,800 to start with.