Before discussing the numbers thought I think it’s important to understand the the design ideas and philosophy for this built. as we all know U20s can make a lot of power but it tends to be higher up in the revs in the 6500-8000 rpm range , that great and lots fun but not really practical for everyday street use unless you’re always pushing it . I personally prefer a car that is quick off the line and doesn’t require you to wind it I all the time to get the most out of it but that is capable and willing to reach higher up when needed.
After talking with multiple builders I selected JT at Datsun Restoration Products (DRP) for this built because I felt he understood what was looking for and adhered to a similar philosophy, we discussed many options and looked at all the pro and cons before making a decision selecting components for their functionality towards my target not output numbers ( we actually never discussed output ). Amongst uncommon choices we made for a high output U20 we decided to run Mikuni 40s as we felt that while we would sacrifice some peak HP at the higher revs we would make more usable power an torque at lower revs , ditto for the cam selection we went with a custom cam that’s somewhere between a A and a B to bring the power a little lower in the rev range .
This combined with a LW billet flywheel makes for very tractable engine with a nice spread between peak torque and peak HP. Peak numbers are 120hp and 132lbs respectively at the wheels but more important than max numbers is the way the power is delivered , of the line at 2500 rpm the engine is already making about 110lbs and increase rapidly to be passed 120lbs at 3000rpm and stay over that number all the way to 5200 where we hit peak HP.
I’m super happy with the results and again a HUGE thank you to JT and DRP this is an awesome built and love the way the car feels. Obviously, we could potentially make a lot more peak power with 44s and a bigger Cam but I seriously doubt it would be quicker to 100mph
Test details:
-U20,custom cam, 123Ignition, Mikuni PHH40 with 35mm venturi , LW flywheel , Air cleaners on , 91 octane , max timing 35 at 4K ( advancing timing further made basically no big differences)
-We initially made 116/129 leaning the pilots a slight bit gave us the final
-We tested on a Mustang dyno which as I understand it usually gives a lower number than a Dynojet because it is under load
- Since the engine has less than 1000 miles I asked the operator to stop each of the pulls a 6K rpm it was still pulling but power was tapping of anyway
thanks for reading
