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1985 SD33T MK LWB Wagon
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Discussion Starter · #1 ·
Alright, so, I've been pretty quiet on the forum since I had my final exams, and then went to Fraser, but I've done a fair bit of thinking over the past few weeks and need some opinions. I know that SD33T's are notorious for cracking heads when pushing more power than stock, however I don't know the threshold where is a 'safe' amount of extra power. I had the thought the other day that surely they only crack heads when the extra power comes from adding extra fuel and boost into the engine (correct me if I'm wrong), so doing performance upgrades like a free flowing exhaust/turbo elbow delete, intercooler, and in my case plumbing up the snorkel so it's sucking cooler air in the first place, won't affect the engine's durability as it does not put more stress on the engine, in fact it may put less stress on as it is able to do it's primary job of spinning the crankshaft with less restriction. So I have a couple of questions:

-Is my theory of non fuel/boost-related upgrades reducing likelyhood of head cracking correct?
-What actually causes the head to crack? (I have an egt gauge and always make sure to keep egt's below 475*C post turbo)
-How much extra fuel and boost is agreed to be absolutely safe to put into the engine without worry of cracking the head? If any.
-How much of a difference does removing the horribly restrictive 90* elbow after the turbo make? I've had a bit of a look around on the binder-planet forum at some of the guys in the USA with SD-powered International Scouts, and a few people there seem to have had good results by removing it.
-How easy is it to remove the elbow, and does it tie into anything else such as the wastegate which complicates the removal? Or is it a simple unbolt 3 bolts and bolt new exhaust onto turbo?
-And just for speculation how well would a dawes-valve powered GT2052v VNT Garrett turbo from a ZD30 work on the sd? Dad (@trev zd30) will be replacing his soon, and I'm in need of a new turbo anyway (my turbo seals are pretty leaky), so we figure that if we could make it bolt on it could work well as it is plenty capable of producing the 7-10psi of boost that the SD33T runs from factory (7psi with muffler, 10 without from my experience). Would it be easy enough to adapt to the SD mounts?

Big post I know, but I figured it's probably better to make one thread with a few burning questions than many threads of one question each. Thanks everyone.
 

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1985 SD33T MK LWB Wagon
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Discussion Starter · #3 ·
Having a feedpump before the injectorpump is noticable in power. Also starts quicker


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Yep, already got an electronic lift pump from the p/o who had a cleveland in the old Mk, I’m running 2psi in it, should I run more?


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I think 3-4 psi is good. Smaller boats with 3-5L diesel engines have 5.5psi ish


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I so happen to own two IH Scouts both diesels, one has the Patrol Motor. The other is 1980 with slight modifications. The main issue with these motors is lack of cooling. No intercooler, so that is critical to lowering exhaust temperatures. A front mounted intercooler with 2.5” pipes is an easy way to address that.

Oil cooling is also critical cause under load oil tends to breakdown faster with temperature increases. So an external oil cooler is also a fix to the lack of cooling capacity of the engine design. Perma-cool part No. 189 is an oil sandwich adapter plate that bolts up to your spin-on oil housing and filter. You can run oil lines to a thermostatic electric oil cooler that can easily mount to the inner fender wall.

By simply addressing those two issues you can extend the life and get a little more power without compromising pistons and cylinder head.

Boost can now be set to 10-12psi by simply adding a boost regulator, vacuum air restrictor to the waste gate and have no negative effect on the engine at all.

Eliminating the dog leg exhaust can also be of benefit a custom down pipe will help with flow.

This is my setup, not claiming big power gains but it’s built to last.







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1985 SD33T MK LWB Wagon
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Discussion Starter · #7 ·
Have you had your injectors replaced? Amd maybe think of a water meth setup
Haven't had the injectors replaced, no. Just curious, do you know how that helps with power?

The main issue with these motors is lack of cooling. No intercooler, so that is critical to lowering exhaust temperatures. A front mounted intercooler with 2.5” pipes is an easy way to address that.
An external oil cooler is also a fix to the lack of cooling capacity of the engine design. Perma-cool part No. 189 is an oil sandwich adapter plate that bolts up to your spin-on oil housing and filter. You can run oil lines to a thermostatic electric oil cooler that can easily mount to the inner fender wall.

Boost can now be set to 10-12psi by simply adding a boost regulator, vacuum air restrictor to the waste gate and have no negative effect on the engine at all.
Eliminating the dog leg exhaust can also be of benefit a custom down pipe will help with flow.
Thanks for the fantastic input Mike, this is exactly the kind of info I'm looking for.

A couple of questions for you:
How much did you notice your EGT's drop after adding an intercooler?
Does the perma-cool adapter just spin on to the oil filter housing?
After all is said and done, I know it's mostly for reliability and longevity of the motor, but was there a noticeable increase in power to make it somewhat better to drive around town?

Like you, I'm looking for just a bit more driveability but also looking to make the engine go a long long way, so everything you mentioned is perfect. Also having a little more power means I hopefully won't have to floor it to get anywhere, like I have to now. I'm considering taking it to a dyno in it's current stock state to see what kind of whp it's making, just because I'm genuinely concerned it's tooo slow, even for an SD, and might not be the healthiest of engines.

Thanks everyone for the input so far, keep it coming, it's great to read through everyone's suggestions, as everyone has different opinions and experiences, so it gives a good range of info.
 

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Rust is just natural weight reduction.
1986 SD33T SWB
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Alright, so, I've been pretty quiet on the forum since I had my final exams, and then went to Fraser, but I've done a fair bit of thinking over the past few weeks and need some opinions. I know that SD33T's are notorious for cracking heads when pushing more power than stock, however I don't know the threshold where is a 'safe' amount of extra power. I had the thought the other day that surely they only crack heads when the extra power comes from adding extra fuel and boost into the engine (correct me if I'm wrong), so doing performance upgrades like a free flowing exhaust/turbo elbow delete, intercooler, and in my case plumbing up the snorkel so it's sucking cooler air in the first place, won't affect the engine's durability as it does not put more stress on the engine, in fact it may put less stress on as it is able to do it's primary job of spinning the crankshaft with less restriction. So I have a couple of questions:

-Is my theory of non fuel/boost-related upgrades reducing likelyhood of head cracking correct?
-What actually causes the head to crack? (I have an egt gauge and always make sure to keep egt's below 475*C post turbo)
-How much extra fuel and boost is agreed to be absolutely safe to put into the engine without worry of cracking the head? If any.
-How much of a difference does removing the horribly restrictive 90* elbow after the turbo make? I've had a bit of a look around on the binder-planet forum at some of the guys in the USA with SD-powered International Scouts, and a few people there seem to have had good results by removing it.
-How easy is it to remove the elbow, and does it tie into anything else such as the wastegate which complicates the removal? Or is it a simple unbolt 3 bolts and bolt new exhaust onto turbo?
-And just for speculation how well would a dawes-valve powered GT2052v VNT Garrett turbo from a ZD30 work on the sd? Dad (@trev zd30) will be replacing his soon, and I'm in need of a new turbo anyway (my turbo seals are pretty leaky), so we figure that if we could make it bolt on it could work well as it is plenty capable of producing the 7-10psi of boost that the SD33T runs from factory (7psi with muffler, 10 without from my experience). Would it be easy enough to adapt to the SD mounts?

Big post I know, but I figured it's probably better to make one thread with a few burning questions than many threads of one question each. Thanks everyone.
@Scout2mike has hit a lot of good points.

I'll try to add a little. And keep it under an essay.
It is almost impossible to give a figure on what is safe. These are old engines, a lot have copped a fair amount of abuse and neglect, and a few are getting worn out.
Yes heads are a weak point when pushing more power, but I have pulled apart both completely standard NA and turbo engines with cracked heads. High cyl temps are the biggest killer of heads, high cyl pressure doesn't help, but given N/As are perfectly capable of cracking heads, that is not the only issue.

Then there's crankshafts, they are the next weak point. I don't know anyone who has made a head and crank live long enough to find the next weak point, but my money is on con rods. I have wanted to fit a GT2052V for a fair few years now, and in the mean time I know of 2 other people who have done it. Both broke cranks. They were both running waste gate control instead of a vac actuator and I think a regular boost controller, so max boost at low RPM. I suspect high boost at low RPM causes harmonics that do not agree with the SD crank, using something like a GFB D-Force and using a pressure that controls both the rise rate and max boost of the turbo will help with longevity, or ideally electronic boost control so boost vs throttle position vs RPM can be mapped, but that requires something like a Digibooster and additional engine sensors.
Bolting a GT2052V on will require an adapter, the SD manifold uses a regular T3 flange, the GT2052V uses a 3 bolt flange.

The dump pipe is pretty crap. There is also the turbo-block mount between the turbo and the dump pipe, that will have to be removed or modified to get any gain from a 3" dump, but it is worth it. The Scout item appears worse than the Patrols, but that is not to say the Patrols is any good.
As Mike said, oil cooling can be upgraded, added bonus is less load on the water cooling system. Intercooler is also beneficial, pressurising air leads to heat and the standard turbo is not exactly the pinnacle of efficiency in any measure.

This post sounds pretty negative lol. But it doesn't take that much to wake the SD up and make it a whole lot nicer to drive, but it will never make big power.
You are on the right track with intercooler, upgraded oil cooling, exhaust and turbo. To take advantage you will need a bit more boost and fuel but as long as the engine isn't about to drop its guts anyway, it'll be fine.
I made it over 140,000km on a 520,000km engine by throwing every bit of boost and fuel as I could at it, when I got the engine it was so full of sludge that I could not pour more than a litre of oil in without it overflowing the rocker cover, overfuelled badly etc, only recently did a head. All I did was keep EGT under 550 most of the time, and didn't overheat it. I never planned on keeping this engine forever so while its annoying that it did a head, I'll drop one back on and do the exact same thing again since the bottom end is still holding together lol.
 
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Discussion Starter · #9 ·
@Scout2mike has hit a lot of good points.

I'll try to add a little. And keep it under an essay.
It is almost impossible to give a figure on what is safe. These are old engines, a lot have copped a fair amount of abuse and neglect, and a few are getting worn out.
Yes heads are a weak point when pushing more power, but I have pulled apart both completely standard NA and turbo engines with cracked heads. High cyl temps are the biggest killer of heads, high cyl pressure doesn't help, but given N/As are perfectly capable of cracking heads, that is not the only issue.

Then there's crankshafts, they are the next weak point. I don't know anyone who has made a head and crank live long enough to find the next weak point, but my money is on con rods. I have wanted to fit a GT2052V for a fair few years now, and in the mean time I know of 2 other people who have done it. Both broke cranks. They were both running waste gate control instead of a vac actuator and I think a regular boost controller, so max boost at low RPM. I suspect high boost at low RPM causes harmonics that do not agree with the SD crank, using something like a GFB D-Force and using a pressure that controls both the rise rate and max boost of the turbo will help with longevity, or ideally electronic boost control so boost vs throttle position vs RPM can be mapped, but that requires something like a Digibooster and additional engine sensors.
Bolting a GT2052V on will require an adapter, the SD manifold uses a regular T3 flange, the GT2052V uses a 3 bolt flange.

The dump pipe is pretty crap. There is also the turbo-block mount between the turbo and the dump pipe, that will have to be removed or modified to get any gain from a 3" dump, but it is worth it. The Scout item appears worse than the Patrols, but that is not to say the Patrols is any good.
As Mike said, oil cooling can be upgraded, added bonus is less load on the water cooling system. Intercooler is also beneficial, pressurising air leads to heat and the standard turbo is not exactly the pinnacle of efficiency in any measure.

This post sounds pretty negative lol. But it doesn't take that much to wake the SD up and make it a whole lot nicer to drive, but it will never make big power.
You are on the right track with intercooler, upgraded oil cooling, exhaust and turbo. To take advantage you will need a bit more boost and fuel but as long as the engine isn't about to drop its guts anyway, it'll be fine.
I made it over 140,000km on a 520,000km engine by throwing every bit of boost and fuel as I could at it, when I got the engine it was so full of sludge that I could not pour more than a litre of oil in without it overflowing the rocker cover, overfuelled badly etc, only recently did a head. All I did was keep EGT under 550 most of the time, and didn't overheat it. I never planned on keeping this engine forever so while its annoying that it did a head, I'll drop one back on and do the exact same thing again since the bottom end is still holding together lol.
Thanks James, that’s awesome info you’ve just given me. From what I read in your post would I be better off bolting on a HT18, which would be both easier, and wouldn’t build boost at a low rpm, instead of the GT2052V which as you say would potentially build boost too early. If the main cause of cracking pistons and heads is in fact temperature, that’s ideal since temperature can be monitored and controlled, and measures can be taken to prevent heat such as intercooling and water/meth injection, which probably means it can take a bit of boost and fuel before something breaks. If the crank is the next weak point, that would make sense considering the 4-bearing system it uses, and it would make sense that a high-boost low-rpm scenario would be the main cause of cracking because of the high torque forces being put on it compressing that much air without a lot of inertia to help with the compression. If that is the case, I figure the engine can probably take a good amount of boost and make some decent power as long as the boost comes on after 2-2500 rpm, and assuming combustion temps can be controlled through intercooling, water-meth, and a more efficient turbo that doesn't heat the air up as much in the first place.

I always keep my EGT's below 475, so I reckon I'll have an even better chance of making the engine go further than yours keeping below 550, and if I do go with an intercooler and more free exhaust it should be even easier to keep that EGT level down. I'm not sure yet whether I will go with a water/meth setup, I definitely won't straight away but later on depending on how it goes I may consider it. I would much prefer to make power and still be reliable on a self-sufficient engine so to speak, not needing to refill a water/meth if I don't have to, so I'll try to make it work without.

I've also just had a conversation with dad in the middle of writing this, and he says that if we could pull an rpm signal from the alternator, and add a maf sensor somewhere in the intake, we could use a @Phdv61 "magic box" to control boost vs rpm, so that it would only build full boost when it has enough rpm to take the extra compression. The GT may be back on the cards yet :D

Something that I should add is that at the moment my cooling system is working too well, I don't know if it's because my thermostat isn't working or another reason, but the radiator I'm using is the same one as the P/O used with the 351 cleveland, and it looks identical to the factory one, but my water temps cruising around town are sitting between 60-75*C, and only reach 80 occasionally after a good amount of time at full throttle. And all of this is happening without radiator shroud to direct the fan to pull air through the radiator. I'm not sure how to solve this as from my understanding diesel engines use more fuel and wear out prematurely when operating too cold. Any ideas?
 

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Rust is just natural weight reduction.
1986 SD33T SWB
Joined
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11,278 Posts
Thanks James, that’s awesome info you’ve just given me. From what I read in your post would I be better off bolting on a HT18, which would be both easier, and wouldn’t build boost at a low rpm, instead of the GT2052V which as you say would potentially build boost too early. If the main cause of cracking pistons and heads is in fact temperature, that’s ideal since temperature can be monitored and controlled, and measures can be taken to prevent heat such as intercooling and water/meth injection, which probably means it can take a bit of boost and fuel before something breaks. If the crank is the next weak point, that would make sense considering the 4-bearing system it uses, and it would make sense that a high-boost low-rpm scenario would be the main cause of cracking because of the high torque forces being put on it compressing that much air without a lot of inertia to help with the compression. If that is the case, I figure the engine can probably take a good amount of boost and make some decent power as long as the boost comes on after 2-2500 rpm, and assuming combustion temps can be controlled through intercooling, water-meth, and a more efficient turbo that doesn't heat the air up as much in the first place.

I always keep my EGT's below 475, so I reckon I'll have an even better chance of making the engine go further than yours keeping below 550, and if I do go with an intercooler and more free exhaust it should be even easier to keep that EGT level down. I'm not sure yet whether I will go with a water/meth setup, I definitely won't straight away but later on depending on how it goes I may consider it. I would much prefer to make power and still be reliable on a self-sufficient engine so to speak, not needing to refill a water/meth if I don't have to, so I'll try to make it work without.

I've also just had a conversation with dad in the middle of writing this, and he says that if we could pull an rpm signal from the alternator, and add a maf sensor somewhere in the intake, we could use a @Phdv61 "magic box" to control boost vs rpm, so that it would only build full boost when it has enough rpm to take the extra compression. The GT may be back on the cards yet :D

Something that I should add is that at the moment my cooling system is working too well, I don't know if it's because my thermostat isn't working or another reason, but the radiator I'm using is the same one as the P/O used with the 351 cleveland, and it looks identical to the factory one, but my water temps cruising around town are sitting between 60-75*C, and only reach 80 occasionally after a good amount of time at full throttle. And all of this is happening without radiator shroud to direct the fan to pull air through the radiator. I'm not sure how to solve this as from my understanding diesel engines use more fuel and wear out prematurely when operating too cold. Any ideas?
I wouldn't go down the HT18 route, all the drawbacks of a HT15 but they are a larger turbo, so more laggy on the smaller capacity SD vs the TD. Something like a Mamba GT2554 kit would be a better match - still has T3 flange to suit the SD manifold, and the SD/TD 6 bolt dump pipe flange.

Yes on a standard engine temps seem to be the big killer, it is surprisingly easy to get very high EGT on a bone standard SD33T. I would assume once you start adding a bit of power stuff like harmonics, cylinder pressure, head and block flex etc come into play, but no ones measured any of that on an SD, so I couldn't be 100% sure.

I reckon the ZD turbo could work alright, I still want to give it a crack myself with a proper control system, as long as you can control the spool up well enough to keep it out of crank snapping territory it should be a good thing. Plus being a more efficient turbo it should theoretically be more responsive even if following a similar boost curve,

Yeah engines have a designed operating temperature, and 65-70 is pretty low, and you are correct that it won't be as efficient and may experience a bit more wear, I doubt it would be measurable in engine life though. I'd replace the thermostat since that is the control of the cooling system so it may be sticking open. I like genuine Nissan ones as you can get 77, 82 or 88C and the outlet in both the ones I ordered was noticeably larger than the aftermarket 'high flow' unit I replaced lol.
 
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