1st start with rebuilt turbo

[Dave WM]

I am kind of leaning toward bagging the idea of running the turbo with the stock efi, just too much to go wrong there. this leaves me with 2 options.

just get a COTS efi that can support a turbo with modern sensors OR delve into the OE turbo EFI stuff (which i got with the engine) and try to hook it all up. Its in pieces so it will take some work to figure out, and hope its all there, will not know for sure until I do some research.

Either way I think I will build a new engine test stand. I really like having the NA stand as its very easy to setup a engine on it, building the stand it not that hard and does not take up any more room than engine stand used for tear down.

I am kinda running out of steam on the project, as cooler temps approach and more outside temptations present. Cycling in Florida gets real nice in the coming months, and I have to think about my hiking and road trip plans. I may try for my east coast road trip soon before winter sets in.

[Dave WM]

 

[Captain Obvious]

Well I know very little about turbos and what's considered "normal", but I really don't like the stiffness of that turbo. Maybe it'll loosen up after the seals run-in, but I have no idea.

Maybe some of the turbo guys can chime in and provide some guidance.

[Dave WM]

I am considering just hooking the manifold up to my car if I can figure out an easy solution to the exhaust, and running it like on the test stand. That way I can get some real world experience as far as getting it under loads and see if the break in is the issue. Yes Please guys with exp on these types of turbos (carbon seal) chime in. I have found some other old post from sites like Hybrid Z that would tend to agree with the carbon seat very tight turbo, but I am not a member there and the post are often quite old, still seems that was the deal.

[w3wilkes]

Just a word of caution on turbo. I used to have a '77 930 and the thing you had to keep in mind was you needed to have the car pointed in the direction you wanted to go before putting the hammer down to avoid having the back of the car pass the front of the car. The other thing was "turbo lag". It seemed like it took forever after you put the hammer down for turbo boost to kick in and it would then nail you to the seatback.

[Patcon]

930's especially

[cgsheen1]

Dave, did you post the specs of that engine and the modifications you've made? What turbo is that?  Then I'm wondering why in hell you're using an L28E ECU to try to run a turbocharged engine. 

It's a good thing you have it in a situation where you're not inducing any load. It will not build boost (the boost you get will be at zero manifold pressure) while not under load. (my L28ET running 5000 RPM in NEUTRAL will not build boost) You need a proper ECU. On a stock L28ET that would mean a 1981 280ZXT ECU with dropping resistors OR 1982-83 280ZXT ECU without dropping resistors OR a tunable standalone ECU. 

You're giving more weight (credit) than you should to the O2 sensor. The early ECU does NOT poll the ECU constantly to regulate fuel. Most of the time the ECU completely ignores the O2 sensor and runs off the maps. The ECU tunes cruise AFR under certain limited conditions, in a certain RPM and LOAD range. Even the more sophisticated turbo ECUs of the 80's use basically the same strategy. 

Do you know for certain if your FPR will RAISE fuel pressure under boost? You can break pistons in an instant if you're hot and lean and mis-timed under boost. Ignition timing is another aspect that needs to be controlled properly. Your posts above throw up all kinds of red flags to me - but it's your engine...

I have a stock L28ET intake manifold. It's a bit more sophisticated than one might think - even has a built-in "blow off valve" (that's not what Nissan calls it though). Most of us turbo-swap guys don't use them, opting for a custom intake manifold, the cleaner early 280Z non-EGR manifold, or the like. But, as soon as you ditch stock, you need a tunable ECU. You can add a Nistune daughter board to an L28ET ECU, use Megasquirt, or AEM, or... but you need the ability to tune the maps.

Man... There are SO many things here... Turbo lag. I did my turbo swap in 2008 - running stock in early 2009. I've used 3 different ECUs and about to go to a fourth. Stock turbo, Chinese T04E (which I've run for 8 years or more). Stock J Pipe, custom charge pipe, custom charge pipe with same-side intercooler. I've run AFM, MAF, and none of the above with MS3X. I'VE NEVER HAD TURBO LAG - not because I'm a genius - because I have a properly sized turbo and reasonably well thought out charge and intake air piping. I have a turbo that starts to build boost around 2500 RPM, comes on smoothly, and really lets you know it's there when it hits 8 or 9 pounds and beyond. Turbo lag...

Edit:

OH, and get a WIDEBAND!!

Edited August 22, 2022 by cgsheen1

[Dave WM]

no worries, ditching the idea of trying it with the stock EFI setup. I I was doing a thought experiment to answer my own question about why its not spooling up and making boost on the test stand. I assume it takes a LOT of power to spool a compressor wheel up enough to create boost at the volume needed by an engine. With that in mind the amount of drag I am seeing is minimal, assuming that is the drag does not go up with RPM. I just wanted to see if it would spool up, I have seen a lot of turbos where the guy just spins it with fingers and round she goes, but the more I read the more I find out about the differences in journals vs ball bearings and even more about the drag of a carbon seal vs what is called a "dynamic" seal. I seems the carbon seal is used for very good sealing on the intake side (I have also read that carbon seals are used on ac compressors, that would need a very good seal indeed to not lose refrigerant).

Anyway back to my setup. I do have the stock turbo manifold/harness/ECU and sundry sensors, got them with the engine. So the plan now is to stop futzing around and start by sorting all out to a diagram to make sure I am not missing any parts for the EFI, then I will just build another test stand dedicated to the turbo.

If the stock setup eludes me I will consider an aftermarket setup, but the data on those is fast moving, I can see some ads for complete plug and play but those seem like a lot to me (2k+) maybe that's just the way it is but I would rather try the stock setup which I have 1st. I am not in a hurry since my stock NA engine is pretty solid and I have a better NA engine as a spare. Its the one with the MN47 head that has much higher compression. 

Anyway its the journey that motivates me at this point so no real needs for short cuts like the plug and play at least for now. I would however like to tackle pikes peak again and not run out of power above 12.5k feet....

[cgsheen1]

None of my turbos "freewheel" much if I were to spin them with a finger, but they spin a bit. I think however that mine spins whenever there's exhaust to move it. Yours will break-in I'm sure.

Pikes Peak? You're going to need an ECU and maps that compensate for altitude change. That means it'll need a baro sensor, maps for different altitudes, and map switching and/or averaging. I can't remember if the stock L28ET ECU has a barometric sensor or not. My youngest son still runs his turbo-swapped 280Z (swapped in 2006) with a 1990 M30 (F31) ECU made tunable with a Nistune Type 2 daughterboard (11-12 pounds boost and it's a beast). (one can also Nistune a Z31 turbo ECU) Even the low-end standalones have more features generally than the L28ET requires or can use. My MS3X has features that can't be accessed by this old engine but it did give me an easy path to coil-on-plug, full sequential fuel and ignition. 

Phoenix is about 1100 feet and most people don't think of Arizona as mountainous, But Flagstaff is 7000 feet and my son's house in Snowflake is 6000 and they're just close to the mountains. So, we have a bit of elevation change here if you want to go up into the "piney woods".

The basic L28ET engine harness (usually crap after all these years) isn't that complicated. I always advise anyone with an L28ET to scrap the stock harness and build a new one. Most of the connectors are Bosch and easily sourced - new with pins not pigtails. I'm on my 4th harness now (I bought an AEM 506 ECU so I'm building a harness for that right now).

My 260Z is an uphill monster - the turbo engine has that much torque, especially with 12-14 pounds boost. Coming back down, I'm glad I have vented rotors and Porterfield friction - they work best when they're HOT.

[Dave WM]

I crapped out with my NA at 12,500 not fun as I had to turn around on a part that was very scary with an engine that would run for a few seconds only. 

 

[cgsheen1]

So, no altitude compensation in the '75. Once stopped and restarted, was it better? (some ECUs read barometric pressure at ignition ON and use that figure until power off) Now the SU guys are gonna say: Dang, I could have just rolled down my jets (temperature/altitude adjustment knobs) and kept on going! Sucks you got EFI...

The forests in the Rockies are a bit different than in the East, eh. I was raised on the Western slope of the continental divide in Idaho. I thought I knew what a forest was until: A. My wife and I drove across country to Virginia. B. My son and I drove up the West coast to Portland, Oregon. Those are forests.

Edited August 23, 2022 by cgsheen1

[Mark Maras]

These forests are Bigfoot country. Yeah, they're real.

Not sure what you mean by "roll down my jets" but I raised my jets (leaned it out) when I got near 7,000' with my SUs.