EGT for aftercooled vs. turbo only Cummins

[Justin connell]

I have a pair of 6BTs with twin disc 502s (1.5:1 ratio) in a semi planing hull (Henriques Maine Coaster) I put in Seaboard’s Boost/EGT gauges about a year ago and even though the boat is propped to make 2650 RPM fully loaded, I only run the boat around 1600rpms @ 10-12 knots with boost around 6psi and EGTs around 850 while fuel burn is right in line with curves. The engines get to temp (180) no problem and the hull is very comfortable at that speed but pushes water (the boat keel walks/teeters on its keel after 14-15 knots) I have been wondering more generically, if I had the after cooled version of these motors (6BTA @ 250hp), would the EGTs be significantly lower due to the aftercooler?

The thermocouples are right after the turbo in the exhaust elbows, and I am just wondering what should be the highest sustained EGT I should allow, and if the EGT would be lower with an aftercooler, is that just an inherent advantage to having and aftercooled motor?

Thanks

Justin

Topic

[Tony Athens]

1————-Can you or coud you reach over 2600 RPM when doing this?

2————–If you can, do you get on a clean plane??

3————–If so, what is the vessel speed & RPM does it hold on a clean plane?

Tony

[Justin connell]

Thanks Tony,

I guess to stop beating around the bush, if I run the boat at say 2000RPM/15 knots and the hull is not planing but pushing, and the EGTs are up around 1000 degrees, is that sustainable, or do I risk doing damage?

Would the max EGT be higher for a 6BT vs a 6BTA?

Best,

Justin

[Tony Athens]

Justin,

I read this over a couple of times and I’m not sure what your long term game plan is, but the way you have those 6BT’s set up now, and the way you run them, I’d say you have 10,000 hrs plus to look fwd to.

After cooled 250’s will offer you nothing other that something more to deal with, that IMO you do not need or need to ponder about……………Just go fishing & enjoy is what I’d say..

Tony

[Author]

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