Datsun Roadster Forum-311s.org

Just got back from the dyno. I'll post a video and dyno log later. The engine had just 10 miles on it when they put it on the dyno. When he got into it, it smoked (oil) like crazy. Hopefully it will get better after changing the pvc valve and putting some miles on it. It was also running rich (10:1) so I need to drop my fuel pressure from 55 to 42 psi.

The results . . . drumroll please . . . 128hp and 122 ft lbs.

Not too bad for a junkyard engine.

Shannon

Here's the video. SMOKIN'

I thought I should post an update on the status of my SR20 project. I haven't driven the car much since the dyno for a number of reasons:

1) The engine still smokes badly and I'm trying to decide if I should drive it some with some oil treatment and hope that the rings will seal with use or just bite the bullet and rebuild it.
2) The rear of the car shifts when I get into or out of the throttle. I thought I had damaged the differential but, after a complete disassembly and inspection of the RX-7 diff, it was determined to not be at fault. I have not been able to determine why this is occurring but I don't enjoy driving it in this condition. I wonder if the combination of the Volvo monoleafs, RX-7 diff, and extra power from the S-14 are causing this but I'm still not sure. Some on the forum have commented that I need a second torque rod on the driver's side.

A number of people have asked for some detail about how I was able to fit an A/C compressor onto the SR20. I took some photos of the bracket and tensioner so you can all see how it works. The tensioner is a GM product. The photos show the installation on the S-13 engine but is identical for the S-14.

Hi there Shannon happy to see your project is still progressing.

Sorry to hear about the issue with the rear end. I've been going back to the text books and reading up on chassis and suspension design again and I would have to agree with the addition of a second torque bar. It sounds like the monoleafs are twisting. The monoleafs, by themselves, may not have the rigidity to prevent twisting under power or hard breaking. If twisting is the case another solution might be to add a half leaf for add rigidity. Of course this is just IMHO.
Also I might suggest a simple but good read that might help. "Chassis Engineering" by The great Herb Adams. Hope this helps.

I really enjoyed see your car and talking at Solvang, I think I'm going to try the ac mod on a KA.

Cheers
Matthew

I would have to think that a second torque arm making the axle stay straight in the car has to make it happier. Or some other type of 4 link. My car stays pretty happy with the second torque arm.

As far as the smoke, there's only one way to find out. Take a weekend, drive 500 miles, rev it some, burn some oil and fuel treatment. The SRs are pretty durable, just make sure you have some extra oil just in case..

All of this is just my opinion, and before you bet on my opinion, make sure your AAA is paid..lol

Before fabricating another torque arm onto the car, take a couple hours out of your weekend and swap a set of standard roadster springs back into the car and see what happens. NONE of the Datsun 510 wagon guys that I know that play with those mono-leaf rear springs have been happy with them and often complain of weird handling.

Our SR conversion cars seem to do just fine with the single torque arm...

Just something to consider...

Michael

"swap a set of standard roadster springs back into the car and see what happens"

Michael:

I'm going to do exactly that in a couple of weeks. I'll swap the original springs back in the car and see if there's a change.

Shannon

Love my mono-leafs.

Shannon--
Any update? Did you solve the prob--if so how?

Thx!

Jeff:

Sorry I missed your call. I promise to catch up later.

Update: I removed the monoleafs but there is no change (other than a much stiffer ride). The next step is to disconnect the torque rod to see if the is causing the "wiggle". As for the engine blowing oil, I purchased another S14 and I will rebuild it. Right now the car is in the shop getting the air conditioning repaired. One of the "o" rings was leaking and I lost my coolant. I had to dissemble the center console to get to the vintage air unit.

Its been awhile since I posted an update. I purchased another S14 to rebuild since my engine burned oil badly. I found one in Canada for $300 that was missing the transmission, ECU,wiring, exhaust, and a host of other items. I wasn't too concerned since I already had all those parts. Once the engine arrived in the US, it became apparent that this was NOT an S14 . . . it was an S15. But not just any S15 . . . it's an Autech. The Autech is a 11.7 to 1 compression, limited production engine, with a hotter cam, larger sodium filled exhaust valves, a 7600 rpm redline and a special ECU (which I didn't have).

I decided to proceed with the rebuild even though I've never completely rebuilt an engine before. I disassembled the engine and it appeared to have very little wear. This winter (2016 - 2017), I honed the cylinders and installed new rings (from an Infinity G20 since SR20DE or SR20DET piston rings are too wide). I replaced cam and crank bearings, oil pump, valve stem seals and lapped the valves.

I needed an ECU and finding an Autech computer was impossible. I decided to go with an aftermarket ECU from Haltech. I could have found a solution to work using the distributor but decided, in the end, to convert to a coil-on-plug system like the SR20DETs. I then purchased a Haltech Platinum Pro Plug-in (for an S15 DET). I tied a wideband 02 controller, a GM Intake Air Temperature sensor and MAP signal into the ECU and went off to the tuner.

I was hoping for 160hp at the wheels (the engine is rated at 200hp at the crank). The best run was 156hp but it got a little wonky at the top end. I found out the next day why it was unhappy above 7000 rpms . . . it ran out of gas about 7 miles later (I need to recalibrate my Speedhut gas gauge). Bottom line is that it was still making power when we shut it down. We can always try again.

The best part . . . it doesn't burn oil!

Here's a pic of the new engine. Note that the valve cover color of red is different than a "red top" SR20. Since I later converted to a coil-on-plug ignition system, I couldn't use this valve cover since the coils are much smaller. I purchased an S15 SR20det valve cover and powder coated it black.




here are the high compression pistons



"Regular" SR20 pistons rings wouldn't fit due to the high compression. I found that Infinity G20 rings are the correct fitment. They are much thinner.

Did you steal the pistons from a Will Smith/Tommy Lee Jones movie? No disrespect meant

Just when you think its over...there is 2k more
Love that sound!

nice!!!