ANOTHER Datsun Z/LS3/T56 Swap Thread

[Ironhead]

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. 

[walkerbk]

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.

[LLave]

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

[Ironhead]

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.

 

 

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.

[NewZed]

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.

[rossman]

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.

[calZ]

That makes no sense, thermodynamically. Massflow is king when it comes to cooling, assuming you don't reach the point it cavitation. 

[rossman]

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 July 29, 2021 by rossman

[Ironhead]

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 August 6, 2021 by Ironhead

[Ironhead]

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. 

 

 

 

 

 

 

 

 

 

 

 

 

 

Edited August 28, 2021 by Ironhead

[JMortensen]

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.

[Ironhead]

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.

[LooseRocks]

Who makes those wheels?

[Ironhead]

2 hours ago, LooseRocks said:

Who makes those wheels?

 

https://www.jongbloedracingwheels.com/

[lifeprojectZ]

Ironhead-  I am a bit late to the party here, but also want to give congratulations on the result of all your hard work.   That is an understatement.  I can't believe how much custom work you did on everything.  Inspiring.  Don't be disappointed with the issues you are working through, these are the spice of life and no doubt are teaching you (and all of us) much.  I have spent the past week reading intently through all 28 pages of this thread :-() and the posts have given me so much info on products I never knew existed but will now consider on my own project just kicking off.  Thank you.

 

Two questions I didn't see answers/ background on that I would love to hear your thoughts.   1- why did you decide to go with tandem single master cylinders w/o booster instead of a dual master with small booster and proportioning valve?   2- You mentioned that your electric steering assist was a bit erratic when you first did your road test.  Did that ever straighten out, and is the assist consistent / predictable now?   Are you using the road speed sensor or manual control to dial in the level of assist?   Also, do you like the rack gain / ratio you chose from Woodward?   That is the same rack I will be buying from Woodward in a few months, and I was thinking of the same ratio with electric assist in the column.  Sorry, I couldn't keep it to two...

 

 

[Ironhead]

Thanks for the kind remarks.

 

I am not the least bit disappointed that there were a few issues to sort out once the car was running.  Truth be told, there were far fewer than I expected.  Also, the car has never actually "broke down", nor has anything failed in a catastrophic sense that damaged other components.  I have been driving the car a great deal and honestly it has been pretty reliable.

 

Regarding your questions:

 

I went with the tandem master cylinders w/o power boost so I could use a balance bar to adjust front/rear bias from the driver's seat.  It also makes it very easy to swap out master cylinders for different sizes to get a perfect balance of effort and front/rear bias.  I did have to experiment with master cylinder sizing, pedal ratio, and most importantly pad compounds, to have what I considered "good" pedal pressure and acceptable cold braking.  I settled on very aggressive pads (Carbotech XP20) and absolutely love them...great cold bite...zero fade....etc.  The only downside is major squealing when light/moderate braking, like is common in street driving.  I can live with that...as this is mostly a track car.  After the fiddling, the brakes on this car are fantastic...I wouldn't change a thing.  Well, I would like to have had ABS, but the costs and complexity of installing a motorsport ABS system were insane...no way I was going to do that.

 

The electric power steering is sorted.  I started with a Datsun Z specific kit that used a stock Datsun steering column.  That was the setup that I found gave erratic boost, and didn't really seem to respond to the rheostat knob adjustments.  Also, the steering column bearings were shot, and the column would clunk whenever I changed steering direction.  The PS motor that came with this kit was from some weird Renault I believe.  I started from scratch and built a new EPS setup using the Saturn motor and a Woodward steering column.  It took a bit of fab work, but it works perfectly now.  It uses a rheostat knob to adjust the amount of boost.

 

I would recommend ordering the slowest steering ratio that Woodward sells...I can't remember the specific ratio.  I am using the shortened Apex Engineered knuckles, and between those two factors, the steering is pretty quick, much quicker than stock Datsun.  It is also far too heavy to even consider using without some sort of power steering, although the 275 wide front tires are definitely a factor there.  Ignore the steering ratio I said I was using in the thread...I believe that was the "medium" Woodward ratio, which I have since ditched for the slowest one.  The medium ratio was completely drivable with the EPS, but I just found it disconcertingly quick.  I didn't like it.  It was go-cart like. 

 

 

[lifeprojectZ]

I think I bungled/ swapped the words tandem and dual in my question about the brakes, but your answer is completely understandable!   I am going with Wilwood SL6 calipers on front and still unknown rears, and am pursuing an option to keep a small, maybe the OE, booster, as I am kind of addicted to low effort brakes and mine will be mostly a street car.

 

Woodward offers 2.09, 2.36, and 2.62 ratios (Flaming River calls it "rack gain").   I recently ordered an Art Morrison custom chassis for my project, and they only offer a Flaming River rack, of which they use 99% power racks with 2.27 ratio/ gain.  When I looked at the Flaming River manual racks, the fastest ratio I found was 1.75, which I just immediately dismissed as too slow (maybe not?).   I called Flaming River and wasn't really impressed with the guy's technical knowledge and also telling me that no one offers a faster ratio on the market today for a manual rack.  ok, thanks.  hang up.    I told Art Morrison I wanted a Woodward rack, and they even mention them as available in their catalog, but after quite a bit of discussion and detail I won't mention here, they left me on my own to pursue the Woodward rack, and they will design the mounting for it.   I'm not sure how your quick ratio knuckle pivot to pivot length compares to what I will have with the Wilwood pro spindles, so I will compare all of that before ordering the rack, but with your feedback it sounds like the 2.09 is the ticket.   That is, unless I too quickly dismissed the 1.75 ratio Flaming River rack as inadequate.

[Ironhead]

The 2.09 is what I am using.  Keep in mind my shorter than stock knuckles factor into it all too, but the combination feels really good to me.  You will definitely need power steering, particularly if running wide tires, which I imagine you will.  I would guestimate 1.75 is close to stock Datsun ratio.

 

If your goal is primarily a street car, you definitely want to do a lot of things differently than I did.  Mine can be driven on the street obviously, but it's all pretty harsh and kind of kicks my ass after an hour or so.  

[lifeprojectZ]

How many turns lock to lock do you have with your current config?   Does steering with the 2.09 and short knuckles feel tighter than a porsche / vette / other OE sports car or about on par?

 

With all due respect (most sincere!) I hope to do no more than about 30% of the customization that you did     I am setting myself up for harshness as well since I decided on 18" wheels, but I am hoping that the AME suspension and adjustable dampening of the shocks will help me tame it down for street driving.  It will never be a daily driver.    

 

What was your motivation behind the dry sump upgrade to the LS?   Was this out of concern for oiling during cornering, or to gain ground clearance with lower engine positioning in chassis?  As of right now I'm looking at the Holley 302-2 oil pan, which will probably still protrude a bit below my chassis.   Crank centerline to bottom of the 302-2 is 8.25".   I'm trying to go for a flat undercarriage other than that.    All subframe connectors will be eliminated, and I will only be using the 280Z shell on top of the AME chassis.  I do have the benefit of a wider trans tunnel for the exhaust.

[Ironhead]

Lock to lock is about two turns, but that doesn't mean much as I have rack stops in place to stop interference issues at full lock.  I would say the steering rate is similar to a modern Vette or something along those lines.  It still has plenty of lock to do a "U" turn on a fairly narrow street, but not enough for drifting for sure.

 

Much of the harshness in my case comes from the fully Heim jointed suspension....and also very stiff springs.  It handles great, but hates major bumps.  When I hit a bump unexpectedly, it feels/sounds like I broke something....LOL.  I also have very little in the car to absorb sound.  The floor of the car has a coat of Lizard Skin, but honestly that really only takes away the "tin can" ringing...the car is still loud inside.

 

I went dry sump because I have another track car, with a very sophisticated wet sump pan, and I still see the ******* oil pressure light come on during hard braking.  It drives me crazy.  The dry sump also greatly helps ground clearance of course, and I have read multiple accounts of wet sump LS motors having oiling issues on road courses.  Dry sump is better in every way except cost.

 

I think going with a custom chassis is a cool idea.  Best of both words if you aren't concerned with "originality", which obviously I am not....