Youtube on RTV power increase

10-e-c-dirt

Active member
I would suggest if you do this to get a Good exhaust gas temperature gauge, installed in the exhaust manifold Before you make the change to get a baseline, on a Long Hard wide open pull.
 

SVG

Member
You can melt a diesel engine by dumping in too much fuel. As @10-e-c-dirt said, get a pyrometer so you can monitor exhaust temps.
 

aurthuritis

Well-known member
Site Supporter
Thanks Collie
that screw is the fuel rack stop adjustment screw. when you turn it out it allows the fuel rack which is a long bar with gear teeth on it that rotate each individual fuel pump metering sleeve. when the fuel rack is moved it rotates the metering sleeves allowing more fuel to enter the pumps. adjusting the screw allows the rack more travel and turns up the fuel allowed into each pump. it does not affect RPM just fuel delivery. i agree that these engines are derated to meet epa regs.

also in a natural aspirated engine more fuel will not melt the pistons. it actually can cool the combustion and make performance worse. only with a turbo or by adjusting the tiimeing will you melt the pistons.

more fuel can cause gradual overheating of the cooling system.

my opinion is that it is probably safe to adjust the fuel conservatively just until you get a tiny bit of smoke. if the engine is in fact turned down as i suspect the performance should improve. note though that smoke will plug the spark arrestor. adjust at your own risk. just my opinion.
 

SVG

Member
While I’m always open to new information, everything I’ve learned in the last 25~ years of diesel ownership tells me otherwise. I’ll list what I believe to be true.

Diesel engines run cooler in a lean air/fuel condition.
Diesel engines run hotter in a rich air/fuel condition. Adding more fuel creates more heat regardless of induction type.
One benefit of a turbocharger is to clear the combustion chamber of hot exhaust gases with the relatively cooler charge air thus lowering EGT. I’ve got a pyrometer on my modified 12 Valve CTD and before I installed a high flow turbo I really had to watch the EGT’s when towing in the mountains.

If anyone does this mod and has an IR gun they could shoot the exhaust manifold temp before and after test runs as a quick way to see what the temps are both pre & post mod.
 

aurthuritis

Well-known member
Site Supporter
i agree that more fuel will creat more heat. that is why i warned to monitor the coolant temp. adding to much fuel past the point that the mixture becomes extremely rich will create much smoke and can cool the egt. without a turbo to compress the air and burn this extra fuel you are just expelling fuel through the exhaust. this extra fuel can wash the cyl walls though and cause wet stacking. although if the engines are derated to meet epa tier 4 as i suspect then there is probably some advantage to adding a little more fuel. just don't make it a smoker. another trick to make these little engines tier 4 compliant is to use a 160 degree thermostat. this too will rob power.
 
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