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Discussion Starter · #1 ·
I’ve got a 1995 land cruiser 80 series with full armor , bumpers , sliders etc. rooftop tent , drawers etc. rolling on 35s with stock land cruiser gearing . 4 inch lift, I have a 4BT aftercooled VE pump 3200 gov spring . Higher flow injectors. 4l80e trans w od I’m running 2400 RPM at 70-75 mph. So to get to my question , how high is too high of EGTs for cruising speed? When I get on long uphill grades I’ll hit 12-1300 degrees. But on average will cruise around 900-1000 on flats. i have the egt probe located before the turbo on the manifold . Curious is this okay or should i consider switching to intercooled setup or removing the aftercooler altogether ? Truck runs good otherwise.
 

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Depending on altitude, most engines will run in the 600-800 deg F range for general cruising. Generally in the lower end of that scale. Your problems could be various. For most people the normal cruising speed is in the 1800-2000 RPM range. Once you pass 2000 RPM the engine's fuel efficiency goes away. Also, the engines torque output starts to drop after 2000 RPM. At 2400 RPM you will have more HP but less torque which is what lugs a heavy load so the engine is working harder. Second, you have an automatic transmission which is less efficient than a manual. Third, what kind of boost level are you seeing at cruising speed? Often only see 6-8 PSI when just cruising down the highway. Boost builds due to load. And in association with that are you seeing an smoke or haze from the exhaust? If any is present you may be running too much fuel or not enough boost. That creates heat, not more power. The leaner you run a diesel the colder it gets. Exact opposite of a gas engine. Have you made any adjustment to pump timing? A slight advance in timing can lower EGT. The aftercooler used on the 4bt is not the most efficient heat remover. That being said, the water/air aftercoolers are considered the best at heat removal but the Cummins system isn't like you'd find for that application. It is using engine coolant which is already preheated. That system could be made more efficient by using a separate radiator for it and a separate circulating pump. The general issue is usually cost. That's why most go for an air to air intercooler. The Ford 6.7 diesels use a water/air system but the radiator for it is over 4 feet wide.
 

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Discussion Starter · #3 ·
I generally am pushing 7-8 psi of boost at cruising , the cruiser weighs probably around 6k fully loaded , but has enough power to hit 90mph if I wanted. It sometimes goes in and out of OD and temps will bounce between 9-1000, I’ll try lowering the fuel screw a turn and advance timing and see what happens. Im considering going with a bigger turbo and regearing to get my RPMs lower, also I’m not sure the tach is 100% it might be 1 or 200 rpm off. But it’s fairly accurate . I just would hate to get rid of the aftercooler and have to fabricate / find room for an intercooler . I know JDM Toyotas have top mounted intercoolers which would be perfect so I could cut a hood scoop and get fresh air that way. However I would prefer keeping the air to air but like you said it doesn’t seem the most efficient. so I’ll try turning the fuel down and see if I can find a happy medium. It doesn’t smoke unless I punch the throttle at lower speeds. Which is to be expected with the fuel pin. Thanks for the tips appreciate it a lot.
 

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What turbo are you using now? Put your thinking into another gear. Think smaller not bigger. The stock 4bt with the aftercooler used in road applications had the small H1C turbo with a large turbine housing to control heat so there's no wastegate. Good for the stock 120 HP the engine had but not a performance turbo for upping the power. The best turbos would probably be in the HX30W family. Those are light years better than the H1C. The common ones we see are the 44mm standard HX30W or the 46mm Super HX30W. The 44mm version will have the same oil line fittings, 3" air intake, and rear exhaust flange as the H1C. It will be about 1.5" longer due to the wastegate turbine housing. Air outlet will be a 2.5" 90 deg elbow. You'd just have to work out the plumbing. The Super HX30W will require a different oil line, uses a 4" air inlet, and the air outlet elbow is 3". Industrial engines with the aftercooler used the 40mm HX30W. Don't see that one used much since it's not so common. Another note. There were 2 different water/air aftercoolers. The early style would have been on the road engines and the later version was on industrials. The later one probably has a better flow rate. See photos below.
 

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Discussion Starter · #6 ·
What turbo are you using now? Put your thinking into another gear. Think smaller not bigger. The stock 4bt with the aftercooler used in road applications had the small H1C turbo with a large turbine housing to control heat so there's no wastegate. Good for the stock 120 HP the engine had but not a performance turbo for upping the power. The best turbos would probably be in the HX30W family. Those are light years better than the H1C. The common ones we see are the 44mm standard HX30W or the 46mm Super HX30W. The 44mm version will have the same oil line fittings, 3" air intake, and rear exhaust flange as the H1C. It will be about 1.5" longer due to the wastegate turbine housing. Air outlet will be a 2.5" 90 deg elbow. You'd just have to work out the plumbing. The Super HX30W will require a different oil line, uses a 4" air inlet, and the air outlet elbow is 3". Industrial engines with the aftercooler used the 40mm HX30W. Don't see that one used much since it's not so common. Another note. There were 2 different water/air aftercoolers. The early style would have been on the road engines and the later version was on industrials. The later one probably has a better flow rate. See photos below.
Yes the super hx30W is what I was thinking of going with , however wouldn’t timing adjustment and backing off on fuel decrease my EGTs? I have the early style tall aftercooler. Is there anywhere I can read more on these aftercoolers because it seems like they don’t work as good as non intercooled or intercooled , I’m trying to avoid having rip it off and start from scratch since the previous owner never did either , I just want the 4BT to run cool and stay reliable , as I’m content with the power it has but I hate backing off the throttle on climbs to avoid spiking EGTs…
 

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You are not too far off my performance. I have a 2006 Hummer H3 on 35s with 4.10 gearing. I run 2050 rpm at 75. I am non intercooled (hoping to get intercooled soon). I run typically around 900 EGT on flat ground at 75 with about 12 PSI boost on a 40mm Hx-30. Keep in mind with aftercooling water temps of 180, you really aren't going to do any cooling below 10 PSI as your turbo discharge temps aren't higher than the coolant temps.

Backing off the fuel won't help much for the flat ground EGT. You are having to work at a certain load and that takes a certain amount of fueling to get there. As for the constant grades, I see what you are seeing, 1200-1250 with 22-24 PSI. Backing off the fuel a bit will help those peak temps. Advancing your timing a bit will help lower the EGT. Get the right tools to check your pump lift at TDC. I stay below 2.0mm.

I have a pump and 40K coolers I bought to go water cooled but figured out a way to go air to air. You can separate the cooling system and run an isolated cooler that will really lower the coolant temps, intake temps and EGT. PM me if you have any interest in those. I will let them go for a discount from new and they have never been used.
 

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Discussion Starter · #8 ·
You are not too far off my performance. I have a 2006 Hummer H3 on 35s with 4.10 gearing. I run 2050 rpm at 75. I am non intercooled (hoping to get intercooled soon). I run typically around 900 EGT on flat ground at 75 with about 12 PSI boost on a 40mm Hx-30. Keep in mind with aftercooling water temps of 180, you really aren't going to do any cooling below 10 PSI as your turbo discharge temps aren't higher than the coolant temps.

Backing off the fuel won't help much for the flat ground EGT. You are having to work at a certain load and that takes a certain amount of fueling to get there. As for the constant grades, I see what you are seeing, 1200-1250 with 22-24 PSI. Backing off the fuel a bit will help those peak temps. Advancing your timing a bit will help lower the EGT. Get the right tools to check your pump lift at TDC. I stay below 2.0mm.

I have a pump and 40K coolers I bought to go water cooled but figured out a way to go air to air. You can separate the cooling system and run an isolated cooler that will really lower the coolant temps, intake temps and EGT. PM me if you have any interest in those. I will let them go for a discount from new and they have never been used.
I would like to go air to air also , eliminate the complexity of more coolant lines , a pump , etc. I’ll PM anyways to see what you got
 

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You should aim for 7-800 degrees f cruising, holding no more than 1200 degrees on hills, if you want reliability. You never said what turbo your running, but I'd say you have more fuel than air. Also having an air to air instead of factory aftercooler will work better to keep your egts down. Not sure if your actually running that 4bt at 2400 rpm, but best fuel economy is around1800 rpm for cruising. I find above 2k it starts to drink fuel noticeably more
 

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Discussion Starter · #11 ·
I’m running the H1C , and am in the process of trying to tune her to run cooler, I don’t need as much power , I would be happy with turning power down that way I’m not running so hot ,
 

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ok, that turbo isn't the best as a single on the 4bt, similar to the hx35. If your not after big power something in the hx30 family is a good choice. And you might not even need those bigger injectors if your running a small hx30. if you had bosch 190s or something like a 40 hp injector that would probably be ok, not gonna cause too much heat.
 

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Discussion Starter · #13 ·
ok, that turbo isn't the best as a single on the 4bt, similar to the hx35. If your not after big power something in the hx30 family is a good choice. And you might not even need those bigger injectors if your running a small hx30. if you had bosch 190s or something like a 40 hp injector that would probably be ok, not gonna cause too much heat.
Currently looking into super HX30W
 

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The Super 30 is a good turbo and we have quite a few guys running those. The general issue with the factory Cummins aftercooler is it wasn't designed for very high performance. Units using those only gained about 15 HP. A separate radiator and circulating pump would definitely be better than using engine coolant but don't know how much you can improve. Higher EGT's typically come from too much fuel for the boost available, retarded pump timing, or inefficient precombustion air cooling. Can be a mix of all three.
 

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Discussion Starter · #15 ·
The Super 30 is a good turbo and we have quite a few guys running those. The general issue with the factory Cummins aftercooler is it wasn't designed for very high performance. Units using those only gained about 15 HP. A separate radiator and circulating pump would definitely be better than using engine coolant but don't know how much you can improve. Higher EGT's typically come from too much fuel for the boost available, retarded pump timing, or inefficient precombustion air cooling. Can be a mix of all three.


Going to be looking into it this month. Im gonna start with proper timing , bump the fuel screw down a tad and play around with fuel pin .
 

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Discussion Starter · #16 ·
Turned the fuel down a tad and turned the star wheel back a bit , im seeing lower top end EGTs around town, going to try advancing timing more and play around with fuel pins , will report back .
 

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Do you know what size injectors you have? Unfortunately, most companies rate them in HP gain which is pretty much useless. Stock VE pump injectors were 4x.012 Bosch units. .Those will handle up to near 250 HP. The weak point on the VE was the turbo which you've already taken care of. A common upgrade injector is the 5x.012 which is about as big as a VE pump will support. If you get the timing adjusted and fuel then you need to turn up the boost. That Super 30 can easily do 30 PSI with no sweat and a bit more. Having the fuel but not enough air creates heat but not power. If you get everything in balance you EGT may top out around 1000 deg F while your power will have increased. Now all this happens when you are under load. When just cruising down the highway or around town your boost may not exceed 8-10 PSI. At the same time the injection pump should be restricting the fuel to match the load. Under those conditions your EGT should be in the 600-800 deg F area. Would be interesting to have air temp reading before and after your aftercooler. People don't realize that air temp out of the turbo can exceed 300 deg F under heavy boost. Compressed air gets very hot. That's the reason those pieces of rubber hose connections are silicone rated at 500 deg F.
 

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Update-
Considering pulling my injectors and going back to stock, resetting my timing , seeing if that is of any help to cure this issue ..
When at the 200HP tune fresh stock injectors worked really well and were clean from idle up, IIRC I was making 28 psi max boost at the intake manifold. I do not know what the intake temp was but I could firmly grasp the cold side tubing after a long hard run and it would be cooler that ambient engine compartment temp, I have a pretty large air to air so to me it should be that cool. IMO everything you can do to help improve efficiency should be addressed enough 1% or 2% increases and you are getting somewhere your engine will likely live longer as well Space/Weight will always be a challenge when I went to compounds it required new inner fender wells for me to fit the size of plumbing, air box, oil feeds/drains.....
 

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Discussion Starter · #20 ·
Well I’m still running the stock H1C , I’m about to order up the super 30 hoping it will cure my issue , the aftercooler is clearly not as good as an IC but I would rather make do with it, the seperate pump and radiator is something I have looked into but in my opinion it’s more things to fail, I simply want reliability and useable power . With turning the fuel down a quarter down i top out around 1200F on a steady uphill grade at 65 , if I try to stay at 70-75mph @ 2500rpm it will slowly start climbing , however it isn’t as bad as it was before , so hoping this new turbo will atleast drop 200F so since it’s something I wanted to do anyways I’ll go ahead and take care of the turbo and see where I’m at from there . Here’s a pic, 7k lbs fully loaded, shaped like a brick , on 35s with 4:11s
Tire Sky Wheel Car Automotive carrying rack
 
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