[scout4bta]

I took the Scout out for it's first "heavy" tow this afternoon. The Casita was empty about 2500-3000 lbs, guessing. (GVW is 3500). At 65 mph, 1850 rpm, EGT's were at 900 F just down stream from the turbo. This was straight and level on a flat road. Stock fuel setting. timing at 1.45mm. Coolent temp was right at 180F. Even if I shifted down to 4th EGT's remained the same, only if I slowed down to 45 and 3rd did the EGT's come down. It pulled good, got 12 lbs boost in 2nd, 15 lbs in 3rd and 4th, cruzing at 65 boost was about 10 lbs.
I've tried higher and lower timing, nothing changes except the tone of the engine.
Looks like it's it's time for a aftercooler? Any other suggestions?

 

[57 napco]

12cm exhaust housing to start with, then try a charge cooler.

 

[Dougal]

Intercool or more boost.

Intercooling is the better option right now.

 

[CrewCab59]

exhaust will cause high EGT's as well if it's not flowing good or to tight of a bend at down pipe.

CAC will drop those temps as well.

Thanks
CrewCab59

 

[scout4bta]

exhaust will cause high EGT's as well if it's not flowing good or to tight of a bend at down pipe.
CAC will drop those temps as well.
Thanks
CrewCab59

The exhaust is 3", large bends. The muffler is straight thru. But I do have a flex pipe up front, I wonder if that's creating back pressure?

Any one know how to measure exhaust back pressure?
Thanks,

 

[bcowanwheels]

900 is normal operating temp..... any colder and your out of spec,s. it takes a certain amount of heat to build boost !!!!!!

 

[scout4bta]

900 is normal operating temp..... any colder and your out of spec,s. it takes a certain amount of heat to build boost !!!!!!

The exhaust temp is taken down stream from the turbo, about 3", If that were pre trubo I would say yes, 900 is OK.

 

[bcowanwheels]

say what you want but 1000 post turbo is normal also when working the engine.

 

[Dougal]

The problem with post turbo EGT measurement is that it's a guessing game.

If you're getting out of your comfort zone, then drill the manifold, put the thermocouple where it should be. You can use the old thermocouple port in the exhaust to measure exhaust backpressure or just plug it.

At 100km/h (63MPH) the exhaust temp in my Isuzu 3.9 is 380C pre turbo. That's about 700F.
Non intercooled with an eroded turbo compressor wheel, intake temps are approx 90 deg C (190F).

 

[scout4bta]

The problem with post turbo EGT measurement is that it's a guessing game.

If you're getting out of your comfort zone, then drill the manifold, put the thermocouple where it should be. cut,,,,

I would love to, but I dont see any area's on the exhaust manifold that would allow me to drill and tap safely.
Any ideas?

 

[Dougal]

I would love to, but I dont see any area's on the exhaust manifold that would allow me to drill and tap safely.
Any ideas?

Which manifold are you running?

 

[CrewCab59]

Have you looked at your fuel if it's tuned up *unburnt * fuel will cause high EGT's as well.

You need to drill and tap in the exhaust manifold ,900-1000 isn't norm just running.

I'm running 600* @ 70mph unloaded and when pulling my 36ft trailer I'm at 800* @70mph .

Thanks
CrewCab59

 

[scout4bta]

Which manifold are you running?

Stock rear mount that hangs the turbo underneath.

 

[scout4bta]

Have you looked at your fuel if it's tuned up *unburnt * fuel will cause high EGT's as well.

You need to drill and tap in the exhaust manifold ,900-1000 isn't norm just running.

I'm running 600* @ 70mph unloaded and when pulling my 36ft trailer I'm at 800* @70mph .

Thanks
CrewCab59

Stock fueling and it hardly blows any smoke. Unloaded it runs 700-800 at 70 mph.
Are you aftercooled?

 

[CrewCab59]

Stock fueling and it hardly blows any smoke. Unloaded it runs 700-800 at 70 mph.
Are you aftercooled?

Yes, I'm running a intercooler.

Thanks
CrewCab59

 

[sdstriper]

Here's a link for drilling the manifold, I did this without removing the turbo by greasing the drill bit and tap and going slow to remove chips and regrease. Final chip removal using a magnet to fish what was left out (hardly anything).

http://www.dieselpage.com/gipda.htm

A larger turbine housing would reduce EGT and/or you could also get a turbo that moved more air to keep things cooler. Might want to contact someone in-the-know about a different turbo and/or housings. Intercooler/aftercooler would be my last investment for reducing towing EGT, if I were on the quest for big HP numbers I would talk differently though. I personally would reap the benefits of a different turbo vs. intercooler/aftercooler for the dollar investment and potential installation headaches.

 

[Dougal]

A larger turbine housing would reduce EGT and/or you could also get a turbo that moved more air to keep things cooler.

Given the same boost level (i.e. on a wastegated turbo) you are correct that a larger turbine housing will give less backpressure and hence a lower EGT.

But with a non-wastegated turbo, a smaller turbine housing will give more boost, which will provide a greater cooling effect than the heat from the extra constriction.

 

[scout4bta]

Ok, I'm going to try a 12cm exhaust housing.

thanks for the input.

 

[Carl Donica]

Scout, I was going through some of the same problems as yourself with high egt's. My truck is heavy and built like a brick. A couple of months after installation I made an adjustment to the star wheel and full load delivery rate cone under the star wheel. Neither one was "maxed out". This provided ample power and still retained good economy. Did not adjust full power screw! However, Empty truck during warm weather at 65 mph and flat ground would produce 1125* egt pre turbo, 1250-1300 on rolling hils or good headwind. I Would have to slow down on some occasions to prevent possible damage to my engine. Some frustration at this point .After some brainstorming (this is painfull for me!)' I fabricated a fresh air intake with AEM filter. This produced no benefit until I discovered that the JWAC aftercooler was stabilizing charge air temps at above ambient air temps! I stopped coolant flow to the aftercooler and saw an immediate 100* egt drop. Next I started fooling with the pump timing. About 1mm advance produced a slight improvement in egt but a large improvement in highway power. (NOTE: use your pump timing to fine tune your torque curve for best hwy speed power.) I then advanced to 2mm. Egt's dropped about 50-75* but highway power suffered. Also max boost dropped from 14 psi to 8psi. This had my best torque above my cruise rpm. Dropped timing to 1.25mm advance and added 12cm turbine housing, highway torque is perfect for my gearing and tire size at 70 mph, Egt at 70mph flat road is 975*. Max boost came back to 15 psi. The turbo definitely spools quicker. Before 12cm housing I had 0 boost at 65 mph, now I have 3psi at 65mph. Boost climbs quicker an hills because of the quicker spooling which makes the egt's more stable on hills. I usually only gain about 75* on the rolling hills back and forth to work. Before it would be 150-200*! I havent done any heavy towing yet but light towing (4wheeler and small trailer) worked just fine. I could be happy at this setting but tech guy at Gillette Diesel Serv. suggested a compressor wheel and housing would also help so I have that on order. I will ad this info as soon as I have it. Call Steve at 800-638-4679 and have a chat. 12cm housing shipped was only $145. Be aware my engine will turn 2960 rpm but I never use it. Stock setup would pull all the way to this rpm. 12cm housing overspeeds at 2700 rpm and falls on its face immediately! I seem to never go beyond 2600 except for baseline perf. figures for you guys so this is not a problem for me. Hope this helps.
Carl

1979 F-250 crew cab 4 x 4
4 bta with modified H1C
Cold air intake
ZF S-42 5 speed
Borg Warner 1356 x-case
Dana 60 rear
Dana 44 front
3.55 gears
255/85R16 tires (33.5x10.5)
Hydroboost steering and brakes
Custom 40 gal. fuel tank
Much more later

 

[Dougal]

tech guy at Gillette Diesel Serv. suggested a compressor wheel and housing would also help so I have that on order.

Have you got any means to measure your engine intake temperatures?

I stuck a temp probe inside the piping after the turbo and found charge temps in excess of 150 deg C (300F) at 15psi.
Source was a damaged compressor wheel. A good compressor wheel dropped the temps to under 120 deg C. Every degree you get out of your intake temps will take roughtly degree out your exhaust temps.

If a bigger diameter wheel and housing will build boost sooner, then that'd help EGT's and economy. But a wheel and housing that'll simply flow more air and not boost sooner may not help.

It sounds like you could make some big improvements by giving your aftercooler a seperate water system (own pump and radiator).