A few questions during 6lp to 6bta swap.

[Bill Stenger]

Installing 370hp 6bta. In a 28′ 8-9k lb planning hull. Thanks in advance!

#1. Am I safe to delete the fuel cooler? Holds 120 gallons. Generally my longest straight through run is 3 Hrs then back to idling and fishing. I do burn the tanks down to 25% on trips.

#2 Straight run 8′ length of wet exhaust. 6″ or is 5″ safe?

#3 6lp used 1.5″ shaft with 2/1 gear and 19×22 prop. 370 will be 1.5/1 gear and likely a 20/24 or 20/26 prop. Is 1.5″ shaft still sufficient? I need a new shaft anyway since the po used a teflon cutlass bearing that damaged the shaft.

#4 If I go top mount turbo will I need to raise the coolant tank for air bleed purposes? Seems like half the pics show the tank relocated higher.

# 5 Does the smx raw water pump require a 2″intake or will 1.75″ be fine?

Greatly appreciate this site. And I am excited to have this new setup with the smx digital view setup with egt, boost, and hopefully an accurate tach.

Topic

[Dan]

Tony said,
‘’Top mount turbo ?? Are you a v-drive install? But yes,, the tank need to be the “HIGHEST part of the cooling system when running on plane’’

Is this a hard and fast rule? I have space limitations restricting me to either 6 inches below the top of the HX or 12 -15 inches above it.

[Bill Stenger]

Thank you Tony.

#3 I thought it require more prop than that. That is good news i may not have to buy a new wheel. I absolutely plan to prop to 3100-3150. Or whatever ends up being safe according to boost and egt’s.

#4 This is standard straight configuration non vdrive. Reasoning for possible hi mount turbo is for high dry riser clearance. As i am sure it will very tight in back coming off the turbo. I have attached a pic of the back of the yanmar for riser clearance idea. Obviously i won’t really know until the cummins is mounted. Yanmar turbo looks good inside with this old riser configuration. But i want the new one higher so i can engine off flush.

[Tony Athens]

1–Fuel–safe to remove BUT late in the day when the tanks in lo, you may loose some Power at WOT.. Study this:

Understanding Marine Fuel Coolers

2–5″ is fine

3-….Use a 1.5 gear but you’ll never swing that much prop ( your thoughts) .. It won’t even be close…. Remember, your “370” needs to see OVER 3100 RPM and see it EASY when “loaded for bear……….. Stay with the same prop you have until until the dust settles.———–Shaft = 1.5″ done right for a 19-20” diameter prop

4– Top mount turbo ?? Are you a v-drive install? But yes,, the tank need to be the “HIGHEST part of the cooling system when running on plane.

5– The INPUT HOSE size to the pump for any “370” is 2″ .. Thru-hull size can be smaller in some cases and work fine..

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Bill Stenger

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