Cat c7’s

[captcrunch]

Cat c7’s

Have a lead on a good pair at 450hpwith 1.75-1 zf gears. Any thoughts on these motors to replace 671 tibs in my 1988 38c

 

[Captain Ralph]

Re: Cat c7’s

Why?

You may save up to 500 lbs.
You are not saving any room.
You are not going to go much faster.
You will need down angle gears.
Another set of used engines.
You are going to spend a lot of money....
Not sure your in re-power emissions code.

671TIB make 485 HP, have a stronger block and easier to work on.

Did I ask why?

 

[tkbsurf]

Re: Cat c7’s

Don't do it. C7s are marginal at best. Deal or not. I agree with Capt Ralph. Keep what you have. However, If you are going down that road, go with Volvo D8s. The best power, torque and support in the market for that size range IMO.

 

[krush]

Re: Cat c7’s

Cummins QSC

 

[Captain Ralph]

Re: Cat c7’s

Cummins QSC

There you go, Cummins 8.3s. That will fit, save weight, may go faster and eat up some of the checking account also.
The Cummins would make a better package for sure.

Or, Lets clean up the engine room and fix the 6-71 TIBs.
We can then wipe out the checking account on bait, beer and todays fuel.

 

[jim rosenthal]

Re: Cat c7’s

At least two boats similar to yours have been repowered with C series Cummins. They would be the way to go. I owuld stay away from Cats excepting 3406s or 3412s, neither of which would even fit in your boat.

 

[captcrunch]

Re: Cat c7’s

I would love to do the qsc’s haven’t been able to find a deal enough to justify the cost. I can get the pair with gears for the same money I can rebuild one Detroit for and have modern more fuel efficient four stroke power. I was ready to do fpt 570s but the engines didn’t pass a survey

 

[Captain Ralph]

Re: Cat c7’s

I would love to do the qsc’s haven’t been able to find a deal enough to justify the cost. I can get the pair with gears for the same money I can rebuild one Detroit for and have modern more fuel efficient four stroke power. I was ready to do fpt 570s but the engines didn’t pass a survey

Don't pass survey.
What does that mean?
Don't run?
Glazed liners? Blown up?
The important issue; Damaged block or crank???
If the block and crank is not damaged? Fix the Detroits and lets go fishing...

HP cost the same for 2 stroke vs 4 stroke.
The C7s will not get you any better MPG or speed.

Without a down angle clutch, they will not fit. Heck, even with a down angle clutch they still may be to tall.

 

[jap201]

Re: Cat c7’s

How much were the qsc's with gear? Were they new or used? Good engines, if they fit.

I would love to do the qsc’s haven’t been able to find a deal enough to justify the cost. I can get the pair with gears for the same money I can rebuild one Detroit for and have modern more fuel efficient four stroke power. I was ready to do fpt 570s but the engines didn’t pass a survey

 

[captcrunch]

Re: Cat c7’s

New qsc’s with gears are about 110k plus labor The fpt’s had signs of water ingestion on number 6 cylinder on starboard motor.

 

[jap201]

Re: Cat c7’s

what about straight 6cta's @ 430hp each? They're the qsc predecessor. Good mech engines, very reliable, and rebuildable. I would thing those should be 30-40% less than the qsc's from the cummins recon. I had a pair in the last boat, very fuel efficient, easy to work on, loved 'em

 

[captcrunch]

Re: Cat c7’s

They were only about 6k an engine less

 

[Captain Ralph]

Re: Cat c7’s

Oh Fuba!! I thought you said the Detroits did not pass survey and hence my comments. So, I ask, Why replace the Detroit 6-71 TIBs?

 

[captcrunch]

Re: Cat c7’s

I have one that’s took a bad hit from an exhaust leak. It’s hard to justify spending near 100k and overhauling both.

 

[captcrunch]

Re: Cat c7’s

Near 100k on the Detroit’s. I think it will add value to be repowered when I go to sell

 

[jap201]

Re: Cat c7’s

100k to rebuild 6-71tib's seems very high to me. You should be able to get them rebuild for ~3k/hole, plus accessories (turbo, etc) that need to be changed. I would think 50-60 and you'd have almost new 6-71's.

 

[Captain Ralph]

Re: Cat c7’s

I have one that’s took a bad hit from an exhaust leak. It’s hard to justify spending near 100k and overhauling both.

I'm sorry I got confused on your post before.
I think I'm on the correct page now. Please help if I'm still incorrect;

Were talking replacing twin, straight 6-71 Turbo, Inter cooled with by pass blower, Near 485 HP, with good block and crank? Also With some TD (506/509) clutches.
One of them ate some exhaust.
Don't where $100K to fix comes from.

But you want to install some C7s to replace them?
8.3 Cummins cost to much?

I still do not understand why you want to move out a great engine.

Let me say this,
I want to have a truck ready to take your old worthless, $100K to rebuild engines rite out of your boat. I'll have a rental truck and hired driver ready that day to remove your scrap.
Freeport Texas, I'll be there.

 

[krush]

Re: Cat c7’s

100k to rebuild 6-71tib's seems very high to me. You should be able to get them rebuild for ~3k/hole, plus accessories (turbo, etc) that need to be changed. I would think 50-60 and you'd have almost new 6-71's.

And he's in 50-60k and STILL has 6-71s that go how many hours before top end overhauls 1500-2000?

I have a better idea. Rip it all out and stick some 400-500hp outboards on the back.

 

[jap201]

Re: Cat c7’s

100k to rebuild 6-71tib's seems very high to me. You should be able to get them rebuild for ~3k/hole, plus accessories (turbo, etc) that need to be changed. I would think 50-60 and you'd have almost new 6-71's.

Guess I was wrong. Was talking to J&T the other day re: rebuilding 6v92's. Parts have gone thru the roof. A full rebuild, painted, new hoses etc and dyne's would be ~70k ea. So you're 100k for to rebuild 6-71's is right on. Wow, that seems like insane prices to rebuild the old dd 2 strokes...

The one caveat I forgot to mention was they replace everything w/new. He said get the s/n to get an accurate quote. But the 70k was a worst case.

good luck with whatever you decide to do. tough decision at these prices

 

[captcrunch]

Re: Cat c7’s

The pricing and availability on Detroit stuff is going higher and getting harder to get. After some homework considering the c9 cat as an option as it may be a better option