3B N/A EGTs

[dare]

Hey fellas.

I've put an egt probe on my non-turbo 3B and I'm curious to hear if others have experienced the results I'm getting.

It's confirmed something I've always suspected, the max egts increase in proportion to RPMs. Under 2000rpm it's hard to get over 550°c (1020f) and under 1600rpm it won't go higher than 450ish (840f). Highway driving even dropping to 4th (so up to 3000rpm) I can't get above 670ish (1240f).

So fueling increases with rpms. Power increases with rpms until about 3600rpm (where the governor starts to pull fuel) so it's not just VE dropping.

So does everyone elses 3Bs do this or is it just me? It's pretty annoying as when you lose speed going up hills the EGT actually drops, you lose power and it just compounds.

I'd be interested in ways to increase fueling at low rpm. I'm thinking a stiffer spring behind the diaphragm or turning the fitting for the reference line in the throttle body upside down to try and get some vacuum on it.

Out of interest my highest EGT was 754c (1390f) which was belting it up a big hill, towing a trailer, car loaded with a weeks worth of camping gear and overtaking a friends 1HZ (greatest victory of my life). 3rd gear 3500rpm full throttle for probably a few minutes.

 

[duncanrm]

I'd be interested in ways to increase fueling at low rpm. I'm thinking a stiffer spring behind the diaphragm or turning the fitting for the reference line in the throttle body upside down to try and get some vacuum on it.

Sounds like you're willing to have a play!

Assuming your 3B has the inline pump, and not the rotary pump then adding/removing the shims from behind the diaphragm spring is one potential way of affecting fuel delivery across the rev range. Adding shims should increase fuel. All just a theory, I've never tried it, but have thought about trying it..

I'd be keen to hear back on your experience if you do muck about with it, especially given you have an EGT fitted.

 

[roma042987]

Hey fellas.

I've put an egt probe on my non-turbo 3B and I'm curious to hear if others have experienced the results I'm getting.

It's confirmed something I've always suspected, the max egts increase in proportion to RPMs. Under 2000rpm it's hard to get over 550°c (1020f) and under 1600rpm it won't go higher than 450ish (840f). Highway driving even dropping to 4th (so up to 3000rpm) I can't get above 670ish (1240f).

So fueling increases with rpms. Power increases with rpms until about 3600rpm (where the governor starts to pull fuel) so it's not just VE dropping.

So does everyone elses 3Bs do this or is it just me? It's pretty annoying as when you lose speed going up hills the EGT actually drops, you lose power and it just compounds.

I'd be interested in ways to increase fueling at low rpm. I'm thinking a stiffer spring behind the diaphragm or turning the fitting for the reference line in the throttle body upside down to try and get some vacuum on it.

Out of interest my highest EGT was 754c (1390f) which was belting it up a big hill, towing a trailer, car loaded with a weeks worth of camping gear and overtaking a friends 1HZ (greatest victory of my life). 3rd gear 3500rpm full throttle for probably a few minutes.

thanks for posting your experience. Now where are all the guys that swear your turbo diesel is going to grenade when your egt gauge goes over 1000 degrees?

 

[stevebradford]

I have a turbo 3b with turbo at 12psi boost with the fuel turned up a bit no intercooler yet. And was always curious the egt’s without a turbo. Not that far off. Thanks!

 

[dare]

Thanks guys.

Yep she's an inline with the vacuum diaphragm governor.

I'd love to experiment with different springs/shims and so on, I have looked for the Mercedes 240D governor spring that some have run (longer spring, thinner wire) but I couldn't find anyone that would ship them to Australia. I will play with removing the reference line and the angle of it. If I can find the right bits I'd like to try and tee a vacuum gauge into each line from the throttle body and see what is really happening.

It doesn't make a lot of sense to me, one would think at full throttle at low RPM there's going to be very little air speed through the venturi, thus less vacuum in the line and less air trying to cram itself down the cup on the reference line but instead it seems I have the opposite?

I've looked at the FSM And there doesn't seem to be any significant linearity to the output of the injector pump with rpms and having had one in bits, I don't see how there could be. I think the lack of fueling at low rpms has to be something to do with the throttle body, or perhaps one of my lines has a split or leak somewhere. I'm still interested to know if this is normal on 3Bs or just a problem for me.

I'll buy some lines and fittings today and see if I can get some better performance out of it.

Also out of interest, my cruising EGTs vary from about 470c to 620c (880f-1150f) but are generally low 500sC (high 900sF). This is cruising 100-110km/h (62-70mph) and the higher figures were with a very stiff head wind.

 

[350HJ75]

your figures are almost an exact description of my N/A EGT's, I was going to ask on here what people thought about the fact I can peak mine at about 750c!!

As I currently record EGT's via Arduino, I need to get off my butt and add GPS speed / angle sensor and RPM so I can record these values real time and chart them against time. This could then be analysed to show trends etc and comparison runs done with different shims etc....

you can always come and give mine a drive and see how it compares with EGT values but looks very similar to mine. especially losing RPM/speed up a long hill and the EGT's dropping accordingly.

 

[dare]

Awesome, good to know it's not a problem with mine. Or maybe a problem with both of ours haha. Ours really should be about the same, both early BJ73s, new injectors, same altitude ect.

TBH I thought my max egt was going to be higher as I've read a number of posts with people saying they were hitting up to 900c but I guess that's at altitude. In normal driving in mine you'd almost never get above 700, you need to be belting it up a hill in 3rd to get there.

The Arduino project is super cool mate, so much potential.

The fueling falling off as the revs drop seems super odd to me, I mean why would Toyota leave all that performance on the table? Especially in BJ73s where they're already quite underpowered and were pitched as a premium product back in the day. Maybe it's just a function of these diaphragm governors?

 

[gerg]

I've got a bunch of Mercedes springs il ship to ya. Pm me. I found though that with the Mercedes spring my fuel control was difficult. It improved low end delivery by a huge amount but it was hard to control. Made my pedal feel more like an on or off switch. I swapped the stock one back in. Nice that they aren't expensive at all and easy to install.

 

[Freewheel]

This may or may nor be helpful, since my truck is turboed- but I ran it a long time without a turbo and had similar experience.

I would say that in my experience, high egts are entirely about hills. I can't get my truck up to any significant temperature on the flats. I live and drive in the mountains, though, so careful watch on the EGTs is a constant. And highway speeds can get the temps up, when on a long mountain pass, but rarely do I have to pull over to cool down.
The stop and cool down happens on very steep logging roads that I'm climbing in second gear in low range. That gets both the EGTs and the coolant temperatures climbing. I generally adjust my speed to keep the EGTs under 1100F (post turbo) and then watch the coolant temperature and stop to cool down when it gets to ¾ on the gauge.

 

[Greg_B]

This may or may nor be helpful, since my truck is turboed- but I ran it a long time without a turbo and had similar experience.

I would say that in my experience, high egts are entirely about hills. I can't get my truck up to any significant temperature on the flats. I live and drive in the mountains, though, so careful watch on the EGTs is a constant. And highway speeds can get the temps up, when on a long mountain pass, but rarely do I have to pull over to cool down.
The stop and cool down happens on very steep logging roads that I'm climbing in second gear in low range. That gets both the EGTs and the coolant temperatures climbing. I generally adjust my speed to keep the EGTs under 1100F (post turbo) and then watch the coolant temperature and stop to cool down when it gets to ¾ on the gauge.

This thread is great and I wish there was more naturally aspirated 3B EGT info posted. I think you are bang on with your comments on hills (long climbs we can see here in BC). I would add to hills that headwinds are a factor as well. I once drove in my BJ42 years ago for two days heading west, starting in North Dakota and through Wyoming to Idaho. That was a long two days feathering the throttle to keep coolant temps below 220F (no EGT). IIRC my max speed was around 90kmph but most times below that in the 80's. We also closed the kick vents as it was light a blowtorch on the legs.

Your post turbo EGT is 100F more then I prefer to see on mine (running a 13BT so different there as well) but we each pick our max points and that is what it should be.

To repeat: This thread is great and I wish there was more naturally aspirated 3B EGT info posted.

hth's
gb

 

[Freewheel]

I rarely get to 1100, but chose that maximum point based on a bunch of research, and also the AXT turbo being water and oil cooled, so it should run a little cooler than the non water cooled turbos...

 

[dare]

Thanks for the info and offer Gerg. I've seen a few posts of people saying they've removed their merc spring without saying why.

Just out of interest I looked in the manuals to find the length of other Toyota governor springs. The 3B has the longest at 51.6mm, the B is 45.6mm and the 2H has a 43.5mm spring. It doesn't give any info on wire thickness, number of turns, rate or anything but a B or 3B springs could potentially be an upgrade for 2H owners. I looked up the 3B spring (22326-58010) and it's NLA but maybe not to difficult to source second hand.

Cheers fellas. Hills are kinda different for me, on the highway I can't get enough revs to really get EGTs high. To get them high I need something pretty steep to get me back into 3rd. In 4th and 5th I can actually get higher EGTs on the flat than up hill because N/A 3B + hills = a loss of speed. We don't have big mountain passes or anything like that here in W.A so it's very rare to end up back in 3rd.

Head winds are killer, when I bought mine I drove it across Australia and had massive overheating (no egt then) troubles. With a head wind I couldn't go 90kmh+ (often slower) because it would over heat because my foot was fairly well into it but then with a tail wind I couldn't go any faster because there was less airflow through the radiator! On a happy note, now I've replaced everything in the cooling system and upgraded to a larger radiator the engine temp never gets above 82c (180f) which is thermostat temp. I'm keen to see if that changes with the turbo.

Hopefully I'll get some time today to try disconnecting the reference line and the angle of it in the throttle body.

 

[gerg]

I was toying with the idea of trimming the merc spring length to adjust the pressure. It definately delivers more fuel but would need some tweaking. I'm pretty sure if you got them cut to a length that gave you increased performance while maintaining drivability quite a few folks would be interested. If you cover shipping I'll give em to ya. I've got no time for tweeting unfortunately.
g

 

[brownbear]

Actually you do not need to touch springs to increase fuelling. There is a screw on the back of the pump. It is wired for safety. It controls the fuel ratio or fuel input.
I first put on an EGT gauge on my BJ60 before I had a turbo. I bought my cruiser in Calgary where it was sold new. It was pretty slow. When I moved to a lower altitude I found I could increase the fuel a bit and still stay under 1200 F under load.
I found it's not RPM it's foot pressure that controls the heat. A low rpm lugging it up a hill made more heat for me. With a foot deep into it. But shifting down and raising the rpm increases the O2 and keeps it cooler, but you had to stay light on the foot. If I put more pressure onto the pedal it will start to climb in EGT.

 

[gerg]

I changed out my spring when I removed the limiter screw all together.

 

[duncanrm]

Actually you do not need to touch springs to increase fuelling. There is a screw on the back of the pump. It is wired for safety. It controls the fuel ratio or fuel input

The screw you're referring to is probably the Wide Open Throttle Screw.. it only affects fuelling with a wide open throttle.

 

[dare]

I was toying with the idea of trimming the merc spring length to adjust the pressure. It definately delivers more fuel but would need some tweaking. I'm pretty sure if you got them cut to a length that gave you increased performance while maintaining drivability quite a few folks would be interested. If you cover shipping I'll give em to ya. I've got no time for tweeting unfortunately.
g

My thoughts exactly on trimming the springs. Now that I think about it more critically, maybe (particularly with turbo) we want a stiffer spring of slightly less length than stock. A stiffer spring will give greater force on the diaphragm helping the fueling but as it extends and its force drops off it could act more like the stock spring thereby maintaining driveability? Really I need to stick some vacuum gauges on the governor lines to help get to the bottom of this and understand the situation better.

That's a very nice offer Gerg, I'm happy to cover the value of the spring too. I will PM you.

Actually you do not need to touch springs to increase fuelling. There is a screw on the back of the pump. It is wired for safety. It controls the fuel ratio or fuel input.
I first put on an EGT gauge on my BJ60 before I had a turbo. I bought my cruiser in Calgary where it was sold new. It was pretty slow. When I moved to a lower altitude I found I could increase the fuel a bit and still stay under 1200 F under load.
I found it's not RPM it's foot pressure that controls the heat. A low rpm lugging it up a hill made more heat for me. With a foot deep into it. But shifting down and raising the rpm increases the O2 and keeps it cooler, but you had to stay light on the foot. If I put more pressure onto the pedal it will start to climb in EGT.

The fuel screw only limits the maximum depth that the fuel rack/diaphragm can reach, so it only effects maximum fueling. The problem here is we aren't reaching anywhere near maximum fueling under most driving conditions at wide open throttle hence spring swaps and so on. It's interesting yours is different, yours is how it should be.

 

[350HJ75]

so as promised when I got my arduino going with speed and elevation I would do some charts, I have recorded my run to work this morning which includes a decent hill climb of around 300m, not sure of the gradient, and recorded the following chart.

Blue is EGT, Red is speed, Green is elevation

As you can see (and what is expected for a 3B) between the black lines which is the initial steep part of the hill, as elevation goes up speed goes down but EGT peaks and drops down slowly by about 100 deg C over the initial part of the climb, which is what you noted dare that as you are climbing EGT is dropping hence fuelling is being reduced and speed is dropping with it.

beyond the black lines the gradients vary but they are less steep as the initial and therefore I can slowly pick up speed with EGT hovering around 700 deg C

Another note is between the orange lines is where I have gone over a crest and am then running downhill so speed increases and EGT drops dramatically which also makes sense.

 

[dare]

That's super cool 350, thanks for posting. Is that all at full throttle?

The slow ass boat from canada got here yesterday. Thanks Gerg for the Mercedes governor springs. Do you want one 350hj? Any other aussies want one?

I tried disconnecting the reference line from the throttle body but it didn't make any significant difference. I think the throttle response was maybe a little better in the low end but that might be all in my head.

I'm going to collect some governor springs. I know I can get B and 2H (both of which are shorter than 3B), maybe SD33 (MQ patrol) and daihatsu.

 

[gerg]

No problem. That was a slow boat indeed. Course I complain it took a month where as 200 years ago half the people on the ship would have died during the crossing. Selfies anyone?