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ANOTHER Datsun Z/LS3/T56 Swap Thread


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4 hours ago, 280Z-LS3 said:

I would look for other tune solutions too if the SoCal guy's tune day would cost $5K.

 

Full disclosure I have never tuned or had a EFI motor tuned but interest in doing so led me to research the process over the years.  Your previous experience with other race car puts you miles ahead of me.  Does your engine ECU allow for data logging or real time monitoring of timing, air/fuel and other engine parameters?  Not saying the GM tune is inadequate but just double check that things are working per spec.

 

LS1Tech.com is a great resource with plenty of brilliant people willing to help.

 

No, ECU is stock GM part.  I think there is software you can buy to allow tuning some aspects of it, but tunability was not GM's intent.

 

The one thing I learned about tuning, is that you really need to learn to do it yourself.  Doing it right is extremely time consuming and tedious, most of the professional "tuners" around know little more about it than you do, and unlike you they are not willing to put in the time.

 

Also, any slight engine change, even as small as a different air filter setup, will require some re-tuning if you want the car to run its best.  Constantly having to put it back on a dyno to re-tune is maddening.

 

For fuel tuning, the challenge is logging AFR in as many cells as you can.  To do this you wind up doing all sorts of creative things, like driving up steep hills, driving while dragging the brakes, etc.  You always wind up doing some extrapolating of cells based on AFR for neighboring cells....but hopefully as little as possible.

 

Another option, several owners of the same model car I had found that our engine builds were identical.  One guy in the UK had a "no holds barred" professional tune done on his car, then started selling the ignition and fueling data and other parameters to others with the same build. 

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Best thing I did for tuning is by the hp tuners with data logging and hooked up my wide band o2. I was able to do exactly what iron head said by logging 1 day at a time and changing the tune in the evening. Then I went 2-3 days logging and changed the tune. It took about a month to get her just right. 

 

Big thing I learned is to push your spark tables 1 degree forward at a time and then once you get knock back it off 4*. Without a true dino 4* is the safe play to get max power.

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Before tuning, I would check the basics. Maybe replace the thermostat. Put in a high flow version. Also, what did you do with the heater lines? As I understand it, the GM heater valves have constant flow and help keep the thermostat at temp. I made an H fitting... But my car doesn't run, because I am a slacker. 

 

https://ls1tech.com/forums/conversions-hybrids/1891762-proper-thermostat-function-heater-hose-bungs.html

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57 minutes ago, LLave said:

Before tuning, I would check the basics. Maybe replace the thermostat. Put in a high flow version. Also, what did you do with the heater lines? As I understand it, the GM heater valves have constant flow and help keep the thermostat at temp. I made an H fitting... But my car doesn't run, because I am a slacker. 

 

https://ls1tech.com/forums/conversions-hybrids/1891762-proper-thermostat-function-heater-hose-bungs.html

 

I included an "H" in my heater hoses so the coolant would still flow through when the heater (defroster, really) is not in use.

 

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Beyond that, I might have given the wrong impression about the engine's cooling status.  After moving the oil cooler and sealing the radiator area from "leaking" airflow, I took the car out and drove it hard in mid-90s weather and things stayed cool just fine.  I was surprised by how much the fans were running...but that isn't really a problem in itself....that's why it's there.

 

Would the car cool adequately during a 100+ degree track day?  Not sure yet, but it's kind of moot....because I can't deal with 100+ degree track days anyway....LOL.

 

I do know enough about tuning to know that I am not going to mess with the engine's factory tune.  Odds are I would just make things worse.

 

Also, I read on the 'net that in some OEM applications, the LS3 fan doesn't even come on until the engine reaches 225 degrees, or somewhere around there.  That blew my mind....but I guess a hot running engine helps with emissions.

 

Anyway, my plan currently is to call the cooling status "good" unless something happens to change my mind.

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If the LS3 cooling is like many cars, bypassing the heater core actually reduces cooling system effectiveness.  The engineers design the systems with the heater core using just a small amount of total flow.  When you bypass it you create an imbalance that wasn't designed in to the system.  On the L6 a heater core bypass actually bypasses the radiator also because the return line enters the water pump inlet directly, reducing the overall flow through the radiator.

 

Might be worthwhile to examine the flow path of the coolant and consider flow volumes.

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6 hours ago, Ironhead said:

Also, I read on the 'net that in some OEM applications, the LS3 fan doesn't even come on until the engine reaches 225 degrees, or somewhere around there.  That blew my mind....but I guess a hot running engine helps with emissions.

A hotter thermostat slows the coolant thru the engine allowing more time for thermal conductivity from the water jackets to the coolant thus pulling more heat out.

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Yah, after more consideration I believe I'm passing on an internet myth. I'll confirm with one of the thermo analysts at work when I get a chance.

 

Yup, confirmed.  There are "other reasons" to run at higher temperatures but I'm not going to guess or pass on more myths :) 

Edited by rossman
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  • 2 weeks later...
Posted (edited)
On 7/29/2021 at 4:13 AM, rossman said:

Yah, after more consideration I believe I'm passing on an internet myth. I'll confirm with one of the thermo analysts at work when I get a chance.

 

Yup, confirmed.  There are "other reasons" to run at higher temperatures but I'm not going to guess or pass on more myths :) 

 

Respect, Rossman.  Too many on the internet just double down or remain silent when they realize they might have been mistaken.

 

It takes a big person to admit they were wrong.  It takes a bigger person to laugh at that person.....lol.😄

Edited by Ironhead
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  • 3 weeks later...
Posted (edited)

I have been driving this thing longer and longer distances, trying to correct all the bugs and other things that I didn't like.

 

Some of the issues:

 

After 50 or 60 miles, it would shred the serpentine belt.  I found that the tensioner was approximately .12" out of alignment with the other pulleys.  This was strange since the tensioner is a GM LS3 part, but I shimmed it a bit and solved the shredding problem.  Then it started throwing the belt.  I switched to a belt a couple of sizes smaller (shorter) and that problem seems solved.

 

I had minor leakage around the passenger side door when washing the car.  Fixing this was just a matter of loosening the window frame screws, moving the frame inward so it made more solid contact with the seal, and retightening the screws.  All good now (I think).

 

The hatch gets water inside it when washing the car.  I am 99% sure the entry is via the spoiler hardware, and can be fixed with rubber gaskets and thread sealant, just haven't dealt with it yet.

 

Assorted clunking noises from the rear end when going over bumps.  This was partly due to having too long adjusting screws for the rear upper strut adjustment plates.  When the suspension bumped, the upper spring perch was hitting the screws.  Shorter screws fixed that.  It still clunks a bit, which I think is due to the exhaust hitting the hardware for the diff mount.  Still have to sort that out.

 

After re-locating the oil cooler and better sealing the radiator for improved airflow, cooling is no longer an issue, at least not road driving.  Track remains to be seen.

 

The stock steering column had loose bearings, and it was driving me crazy because it clunked when the steering loaded up.  I modified the electric power steering and replaced the column with a modified Woodward one.  Now steering is rock solid.  However, the stock turn signal/high beam controls no longer were viable so I added steering wheel buttons for those things, and also the reverse lockout switch.

 

I am pretty much calling the car done.  I mean, it will never be "done"....but it is fairly well sorted.  I'm sure I will be tinkering with it as long as I own it.  Plan is to put a few more road miles on it (has about 700 ATM) just so I feel reasonably comfortable in its reliability, then do some track days when the weather cools a bit. 

 

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When I was putting mine together I found a bunch of people have issues with the spring loaded belt tensioners, particularly when getting on and off the gas a lot (road racing and autocrossing) so I got a manual tensioner instead. Wasn't that expensive and I've never had an issue. If you have any more problems with that, it's a simple thing to try next.

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11 hours ago, JMortensen said:

When I was putting mine together I found a bunch of people have issues with the spring loaded belt tensioners, particularly when getting on and off the gas a lot (road racing and autocrossing) so I got a manual tensioner instead. Wasn't that expensive and I've never had an issue. If you have any more problems with that, it's a simple thing to try next.

 

If the issues continue, that will definitely be the next step.  The belt is obviously "mission critical" and I am tired of dicking around with it.

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