@Wreckless to think my father in-law left us his SC400 he bought new in 93 I think back in 2006. After the daughter graduated HS in 2008 we re-gifted it to another family member in AZ.

 

Bought my 90 Turbo new and used standard unleaded in it for months or years until a friend suggested I should use Premium for such a fine car. Which I did but since I wasn't heavy footed I didn't notice any difference.

However occasionally it was fun to scare the passengers in the back seat if I didn't warn them I was going to floor it.

That said, I did have the infamous BHG 4 years after purchase, so there's a possibility I did some HG harm. It's still completely stock with whatever HG the dealer put in.

 

so many limitations on the head gasket and why they blow....

1. factory torque. but hey, its 2021....is there really a 7mge running on a factory HG ? (maybe)
2. unknown history. all it takes is one low coolant event and guess what....maybe you slightly warped it. or maybe it ran hot on one cylinder from a bad injector and heat annalled the exhaust side ....and crushed the head slightly (as in the quake thread on here). maybe the cat plugged and roasted her. who knows
3. its a straight 6. big long head. more prone to problems. like an open deck all aluminum 4cyl vs old school aluminum on iron.

I have been piss pounding a felpro "mls" multi layer aluminum foil with magic 3d printed on holograpic seals gasket. ARP studs, torqued down slowly step by step with someone with 5 mf synapses ... and viola....still holding 15-20 lbs boost on piggy back madness. I built this motor before I was married, 14 years ago, it sat for 8 years (magic assembly lube i tell you) and then I got motivated. so beating it for 6 years now. keep coolant and oil in the engine and the 7m will live. dont detonate with "horse piss" 87 fuel and she will live. RPM's and wide open throttle won't kill it, trust me I am trying

 

so many limitations on the head gasket and why they blow....

1. factory torque. but hey, its 2021....is there really a 7mge running on a factory HG ? (maybe)
2. unknown history. all it takes is one low coolant event and guess what....maybe you slightly warped it. or maybe it ran hot on one cylinder from a bad injector and heat annalled the exhaust side ....and crushed the head slightly (as in the quake thread on here). maybe the cat plugged and roasted her. who knows
3. its a straight 6. big long head. more prone to problems. like an open deck all aluminum 4cyl vs old school aluminum on iron.

I have been piss pounding a felpro "mls" multi layer aluminum foil with magic 3d printed on holograpic seals gasket. ARP studs, torqued down slowly step by step with someone with 5 mf synapses ... and viola....still holding 15-20 lbs boost on piggy back madness. I built this motor before I was married, 14 years ago, it sat for 8 years (magic assembly lube i tell you) and then I got motivated. so beating it for 6 years now. keep coolant and oil in the engine and the 7m will live. dont detonate with "horse piss" 87 fuel and she will live. RPM's and wide open throttle won't kill it, trust me I am trying

Actually I know the history pretty well. It's a one owner car (mine) and all stock. But back in the day, I could "point-and-pay" and didn't really pay that much attention to what the dealer did for repairs HG-wise. I'll recheck my receipts more closely.
Interesting that your car sat for 8 years. Mine has sat since 2007 because it was burning coolant but passed compression checks etc. The assumption was coolant erosion into the chamber of cylinder (#6?) because exhaust gas was found in the coolant. Was told to keep driving it but I was afraid to so it sat. Big mistake. Now the tranny has issues going into reverse, coolant light is always on no matter how far topped off, etc.

 

Coolant light being on is the sensor in the overflow tank. They sometimes go bad.

 

Like every ECU it listens for knock and retards the timing from base if it hears bad things. Running regular especially with any mods will result in the ECU deciding to pull some timing in the next ignition event. It isn't slow...engines are slow. Even at redline an old CPU can do a lot of calcs between ignitions events.

 

I have a dilemma here. I generally understand automotive engineering. I went to college initially on an engineering scholarship. I worked at a garage in high school 35 years ago and have the ability to do basic mechanical stuff. I can draw out on paper how an engine works and explain conceptually what is going on. I built a model manual transmission using erector set gears. Could I build an engine? Not likely. Do I get how it works? Absolutely.

I have as a big picture goal getting the more efficiency if I can out of a 35 year old engine platform and also maintaining for as long as possible. I started this thread wondering how changes in fuel affect this particular car so it is a logical corollary that modern other pieces, e.g. aftermarket injectors, could also help. I had never thought about changing that stuff, in large part because the aftermarket world for Supras has been primarily focused on performance and never having been a tuner it wasn't in the front of my thoughts.

I feel like I have two ways I can go. Choice one is the less desirable which is simply asking for help and having someone tell me "Here is exactly what you need to do." like I did with the cooling fans that eventually solved my overheating problem. (Thank you again for that.) Choice two is to learn about this but if that is the route I go I don't know where to start. I can read every thread here but that feels hit-or-miss. Based on this discussion, it seems like an aftermarket ECU could be something worth looking at but I don't know what kind of work that is and most importantly, what risk comes with it. I haven't the first idea how to start learning about engine tuning.

Edit: I have read Wreckless' upgrade FAQ. It is written for performance, however, so it isn't completely helpful except in presenting concepts about which I need to learn more. I went back and read the original listing for my car which includes "electronic boost controller" so it looks like I have some learning to do because I don't know if that is part of the ECU, in addition to the ECU, or even what specifically it does and what model it is.

 

Bear in mind that automaker's have dumped billions into getting more efficiency out of their products. You are not going to get it from a few bolt-ons. Reducing internal friction through design of bearing, low-tension rings, 0W18 oil, and other components like direct drive oil pumps and so on has helped. So has 10 speed transmissions, low-friction drive train components, better aerodynamics, auto-shutoff at idle, ECU control of battery charging, and FEM analysis of combustion chambers. I mean if you want that efficiency, buy a new car. My tesla puts gas in the tank when I regen down a hill. New tech cannot always be backfilled into an old design.

 

I used to get 30mpg on my Supra back when I originally bought it and it was still stock. (Not hwy speeds)
Once the modifying started, I've never gotten close to that again.

I would imagine that with good EGR flow and slightly lean on AFR, you could get decent mileage while cruising.

Though my driving style in the Supra has very little cruising sections anymore.
Wouldn't net me much gain, as I am usually having too much fun with it.

Programming an Aftermarket ECU for efficiency would have a lot of tuners looking sideways with blank stares I would imagine.
That would take a lot of work and Dyno time to get it dialed in for efficiency and driveability.
But it is absolutely something that can be done.
OEM ECU's excel at that, but they have hundreds of hours of adjustments in them.

I've looked into doing this kind of thing on my Tribeca, I already have all the cables and software to do it.
Decided in the end not to screw with my S.O. daily driver, and just keep it reliable and trouble free instead.

 

That would take a lot of work and Dyno time to get it dialed in for efficiency and driveability.
But it is absolutely something that can be done.
OEM ECU's excel at that, but they have hundreds of hours of adjustments in them.

That has also been a consideration of mine, as I figured Toyota already did all the hard work on that end of tuning and they do have hundreds of hours of adjustments, therefore keep the stock ECU. However, in my head, all I can think is that surely "we" have come far enough that a modern stand alone could do it better.

Edit: Just remembered Alex from Humble Performance comparing a Haltech stand alone he tuned and the numbers and ease of getting to those numbers, versus what the time it would've taken using a Hondata setup, which is factory Honda based, and the Hondata would've taken much longer/more difficult.

 

I am crossing my fingers that parts remain available to do this. I have clear title to a car that runs essentially like it did from the dealer for a total of about $16K. I have a lot of money to use over time to apply modern technology as I understand how to do so. My next projects in order are 1) replace the aftermarket rims & tires with OEM rims and tires 2) fix the fog lights.

I need to spend some time learning about tuning. I also need to learn more about what I actually have. The listing included a divorced downpipe and an electronic boost controller.

 

Yeah vehicle tech has come a long ways in 30 years.
There are gains and features to be had over the stock TCCS system.

As you said tuning tools are getting easier and smarter as the years go on also.
The hard part is going to be tuning for drivability in all the areas or scenarios you can imagine.
The harder part is when you encounter drivability problems or scenarios you never imagined.
To have a comfortable and reliable daily driver you need all these bases covered.

 

As you said tuning tools are getting easier and smarter as the years go on also.
The hard part is going to be tuning for drivability in all the areas or scenarios you can imagine.
The harder part is when you encounter drivability problems or scenarios you never imagined.
To have a comfortable and reliable daily driver you need all these bases covered.

This shouldn't be that hard. The stock tuning should cover the parts I didn't optimize. The part I need to optimize is pretty straight forward. My house is about 65 feet above sea level. My office is 13 feet above sea level. My drive is 55 miles one way. The only "hills" of which there are three are highway overpasses. 35 of the miles are on a highway with no stoplights or signs. The rest of it has five stop lights. (I drive in rural-ish country. I see cows and fields of crops every day on my drive.)

 

All that being said though, I actually prefer the old TCCS setup.
It gives the car the character and feel I remember from the day I bought it.
I will likely keep it that way, as is.

I have other things running modern day setups, so I am in no way opposed to new tech. (Except the giant screens and no tactile feedback controls)

 

I could not even read the rest of this (after the 1st 20).. Have got to the part where he says I don't need the vaccine because "reasons"

 

All the details from the original listing are in my profile. If there is something left out ask and I will learn what it is.

 

Taller gears are important here as well. Not sure what rear end you have but for your driving use case you ever to keep that highway speed rpm as low as possible. Something wrist to look at.

 

I have a lot to change. I am sure my 245 front and 275 rears are not helping. Going back to OEM 225’s is my next car modification. That should reduce the mass of rim+tire the engine has to rotate.

 

Figgie gets it.

I use laboratory chambers / dyno's here in my line of work.
The line item cost / purchase orders are so high I can't comment.

I also used to run a 2nd shift vehicle dynometer (cash crop tractors). Power testing / climate controlled chamber, hot vs. cold vs. humidity ect... Endless combinations.
Just the amount of fuel used alone was astronomical.
Excluding the time, engineers and overhead.

 

So I just learned that ECUs are expensive. Having never bought one I was guessing several hundred, not a couple thousand. I can get a used UZ1 from an SC400 for under $1,000, which is my future plan. I would be better off to save the $2K+ it will cost to buy the ECU plus all the time it will take to install and tune it for my eventual swap to a V8. It looks like my mods will have to stop short of a new injection map.

 

I think many of you miss the point that its not the ECU hardware that is driving efficiency, it is the accuracy of the engine characterization and specifically the ability to model the engine behavior and translate that to optimum fuel and ignition events. Today, like 30 years ago, there are only two relevant output variables from an ECU which are fuel injector duration/timing and ignition dwell/timing. That part has not changed. Any ECU can calculate those two parameters with precision far beyond what a carb and distributor could do years ago.

Now you could argue that valve timing is also part of the mix since any modern engine has that now and it certainly plays an important role in efficiency, but the 7M doesn't have it, just another reason why a 30 year old design will never reach the same levels of efficiency as a modern engine, so its not relevant here.

Replacing the TCCS with a standalone will almost certainly be a step back in efficiency. First, the TCCS has millions of dollars of dyno time baked into it. The code was written in assembler so that while the hardware may not be as capable, the software is extremely light and makes up for the 20 MHz clock rate to give you ignition and fuel updates for every power stroke. The TCCS code is full of tables of corrections for temperature, load, altitude, knock, voltage, and so on. Those tables were based on meticulous measurements over all the expected operating parameters of the car, not just room temperature at your local tuning shop. The ignition and fuel enrichment maps are full of bumps and dips that took thousands of measurement to determine. All of this translates into extracting as much performance as they could out of the engine. Good luck improving that with your $1000 "tune".

 

Replacing the TCCS with a standalone will almost certainly be a step back in efficiency. First, the TCCS has millions of dollars of dyno time baked into it. The code was written in assembler so that while the hardware may not be as capable, the software is extremely light and makes up for the 20 MHz clock rate to give you ignition and fuel updates for every power stroke. The TCCS code is full of tables of corrections for temperature, load, altitude, knock, voltage, and so on. Those tables were based on meticulous measurements over all the expected operating parameters of the car, not just room temperature at your local tuning shop. The ignition and fuel enrichment maps are full of bumps and dips that took thousands of measurement to determine. All of this translates into extracting as much performance as they could out of the engine. Good luck improving that with your $1000 "tune".

That is very true, however, it only stays true as long as the powertrain is completely untouched.

 

The fine print says premium gas. If you try to run regular or mid it will feel like you are dragging a ball and chain. I got a tank of bargain price gas that was supposed to be premium (Murphy Oil at Walmart) I could tell right away that it was not premium. I added a bottle of octane booster to get through it and never went back.

 

I am doing an experiment right now with different octane levels of gas. I've been driving with 87. I am going to do five tanks each with 87, 89 and 93 of Shell capturing MPG and miles per dollar. I am on tank three of 87 but look forward to the higher grades.

 

man I would love to data log your knock sensors on that test ....
so what if 87 is the lowest cost per mile if your knock sensor lights up 500 times on the drive VS 50 on 93 octane. a fair answer to that is so what, I don't beat on my car so it will last longer anyway (not meaning to be critical here at all just barfing out ideas / brainstorming...)

I bet one of those colorado/jeep tiny diesel engines would get fantastic mpg--and your in texas right so that makes even more sense right ?

swapping electronics to a faster better CPU / w more features (sequential / cop) coupled with a more modern engine with better combustion chamber design and lighter components ...thats the win. and why not use oem parts if performance goals are secondary to efficiency

 

man I would love to data log your knock sensors on that test ....

If there was some way to log data I would love to do so. I am an engineering nerd at heart. I drive the Supra for the physical platform, not the performance, so there are all sorts of things I would try if I had the money. I can spend on mods & repairs but complete engine replacements is beyond that.

 

Very interesting thread. I just don't understand why anyone would care about fuel economy on a Supra, other than to realize that if it drops significantly then you probably have other issues.

With that said, when I can get 40mpg out of my Accord (not hybrid), I am happy because I drive 25 to 30K a year for my business.

I used to get about 28 on the freeway (Supra) until I started doing stuff. Then it went lower but was consistent.

The higher octane is a no brainer. What if you forget you are cheaping out on fuel and actually drive the car and use the power that Toyota gave you.

I too, would like to see the KS info, I would assume it is some sort of 0-5 volt reading but do not know for sure. Everything else seems to be.

Not judging, just wondering.

 

Very interesting thread. I just don't understand why anyone would care about fuel economy on a Supra, other than to realize that if it drops significantly then you probably have other issues.

Not judging, just wondering.

For me, it's being able to get a certain level of "high performance" / power when I want, while still being able to get "good" mileage, also when I want. Essentially, I want to have my cake and eat it too, and that's why I like this notion of Supra and fuel economy.

Lastly, all this talk of ECU tuning, efficiency, combustion chambers, Toyota probably spending millions to get it right, and that one chevydude couldn't even scratch the surface of that kind of funding, technical, and engineering aptitude; so, why bother with any kind of modification? As such, I'm kinda' getting bummed about updating a '90+.

 

We have a 2000 LS400. It easily nets 30mpg highway. Bone stock, yet it cruises effortlessly, and has all the power I'd need, if / when I want it.

A friend of mine has a Tesla S, it gets around 100mpg-e. Bone stock, yet it also cruises effortlessly, and it actually has a very respectable amount of power.

The biggest difference between these cars? Both were bought used, the Tesla was about 10x the cost. Can buy an awful lot of premium fuel with that difference...

My point is, is the cost of an engine swap or all these other ideas worth it? I mean, at $4/gallon, I could see it eventually paying off, given the OP's driving habits, but I wonder if the value is in the experiment itself? If so, carry on, and post up results! If the end goal is simply to save money, there are easier ways to do it.

On the subject of rolling stock, stock wheels are HEAVY. Do they act somewhat like a flywheel? If so, there might be some benefit to keeping them stock. If not, I'd highly recommend a set of RPF1's, to drop about 9 lbs off each corner. I do that on my cars for suspension and ride quality reasons, but it also makes tire swaps and maintenance easier.

Also, just gonna leave this here...

Homepage - Revolt Systems

ElectrifyingExperience Revolt Systems specializes in developing high output electric drive systems for classic cars and hot rods. Sparing no expense on creating superior quality powertrains that will give you a ride that you will never forget. Our products are proudly 100% engineered...

revoltsystems.com

 

My situation is that I drive 100 miles a day for my commute. The job is worth the commute so I am left having to answer the question "What is the least objectionable, to ME, way to spend two hours a day in a car?" My answer to that question, at this time, is a targa roof Mk III Supra. I don't drive fast, and don't care about performance. I love the way it looks, I love taking the top off, turning up my '80's music when weather permits and I love the way it feels cruising on the highway. There has never been a time owning a Supra I have thought "I'm tired of this. I want something else." I had a driver in a C8 Corvette give me a thumbs up the other day. That never gets old.

If this is the car I am going to drive, I naturally want to make the daily grind better to what degree I can. I am trying to learn what I can about tweaking around the edges to help in the context of "this is the car I want to drive."

Thanks for the link. I first heard about electric crate motors a couple years ago. I am following developments as they happen. I am not opposed to doing an EV swap someday. My problem is that a number of these want to replicate Tesla performance. I want an EV swap that will let me drive like a late '80's Supra. 0-60 in 7.5 seconds and 100 mph is plenty for me. I want to drive a Mk III grand touring car, not a 700 hp 1993 TT Mk IV.

 

Knock monitoring is not a 0v-5v signal...

Is it sound converted into low level ac waveform.

To log knock requires either a seperate standalone knock box such as;

Plex knock monitor v2

PLEX KNOCK MONITOR® V3 - Pro-level Knock Detection System

The PLEX Knock Monitor V3 is a professional knock detection system for data driven tuners. Prevent engine damage with accurate, real-time knock analysis.

www.plex-tuning.com

Link Knock Block

KnockBlock G4+ (KNB)

The G4+ KnockBlock is an essential tool for tuning and can aid in the early detection of incorrect ignition timing, lean air/fuel mixtures and mechanical issues. It is used it with ear buds, headphones or noise cancelling ear muffs and features special filtering to allow you to listen in and...

dealers.linkecu.com

TunerNerd knock monitor pro

Knock Monitor Pro – Tuner Nerd

tunernerd.com

Standalone teed off knock sensor/s while oem still control everything.

Might be others out there but this is a start.

 

Man, I have to say I always admired your knowledge and, how do I say, explaining shit to the rest if us and not acting like we (me) are complete idiots.

Now I just briefly looked and will look more but it indicates that the package includes a new KS.
And this will work on out cars?
Does this replace OEM or just give you another KS that can be logged. I have a ZT2 and I like logging stuff and poring over the data later.
Strange I guess.

Thanks

Dan

 

The good thing for me is my previous vehicle was a Tahoe that got 18 mpg downhill with a tailwind so anything in that area is still acceptable. This is an opportunity for me to do some learning.

 

Every GM LS-based truck I've tuned netted a 1-2mpg improvement JUST FROM CLEANING UP THE VE TABLES. That was on otherwise untouched OEM stock machines.

The OEM tunes for mass produced engines without taking into account individual variations. They are also focused on emissions as Wreckless stated above, and NOT on fuel efficiency. They often do NOT go hand in hand. Example, rev hang in modern manual transmission vehicles, will keep the RPM's high when letting off the clutch because the sudden deceleration creates NOx, or one of those. Guess what, that costs fuel.
Catalytic converters are another (controversial) one. They technically reduce your engine's efficiency by increasing back pressure. Guess what, they cost fuel to run as well, even if they produce a cleaner end result.
On the flip side, something like an EGR setup actually improves both efficiency and emissions, but car guys often like to get rid of that system due to additional complexity - I know I did in the past on a 92 4Runner with the 22RE, and it probably cost me 1 mpg.

All that to say if someone really put the effort into tuning a 7MGTE with modern computers and wideband O2 monitoring, etc., there's certainly MPG gain to be had. Would take time and patience but could be done.

For your specific use case, a higher (numerically lower...) rear gear ratio would likely help quite a bit, get your cruise RPM's down. 3.73's for sure if you don't have those already, and I'm sure there are some even lower options out there if you looked.

Have you looked into hypermiling at all?