Any Merc techs with performance experience?

[magster65]

I'm not planning to do this but I was just pondering potential issues with replacing the 305 mpi short block with a 383 short block and using all the ignition and fuel systems off the 5.0... everything but the short block.
Physically it's a direct bolt it... no exhaust issues, mounting, I'm sure the fuel pumps are good... all the same bolt patterns from the 'vortec' years...
Would the ECM need a different calibration or a replacement from a 6.2 unit? What about the injectors... do they flow enough if the ECM mapping is rewritten?
I guess I could check and compare part numbers on the different engines. I'd like to know if anyone has done this sorta' thing.
Cheers!

 

[magster65]

Apparently not too many :lol:

 

[Lazy Daze]

There is someone here who did it. If memory serves, it was to a '99-'04 260DA - I believe his experiences are in that thread... somewhere.

Here's the thread (but I didn't look through it to verify): http://clubsearay.com/forum/showthread.php?t=23453

 

[magster65]

There is someone here who did it. If memory serves, it was to a '99-'04 260DA - I believe his experiences are in that thread... somewhere.

Here's the thread (but I didn't look through it to verify): http://clubsearay.com/forum/showthread.php?t=23453

Close but that's a replacement engine... not quite what I'm after.
I guess the bottom line is; I'd like to know if it's as easy as swapping the short blocks... a 5.0 for a 6.2... and / or what else is required to make it work properly?
This question may be best posted on a performance oriented site. 99% of Sea Ray owners wouldn't do this kind of project.

 

[Woody]

I don't know about your swap questions but I'm sitting here wondering what my 280DA would be like going 5-10mph faster. To me it already feels a little lite at near 50mph. Maybe a 290 would be different.

 

[Lazy Daze]

Close but that's a replacement engine... not quite what I'm after.
I guess the bottom line is; I'd like to know if it's as easy as swapping the short blocks... a 5.0 for a 6.2... and / or what else is required to make it work properly?
This question may be best posted on a performance oriented site. 99% of Sea Ray owners wouldn't do this kind of project.

Oh, you're right. It's been a while since I looked at that thread. I do, however, remember the puddle of drool that accumulated on my desk!

 

[magster65]

I don't know about your swap questions but I'm sitting here wondering what my 280DA would be like going 5-10mph faster. To me it already feels a little lite at near 50mph. Maybe a 290 would be different.

The 290 feels rock solid at mid to high 40's. It's not so much the wot number I care about but a faster cruise would be fabulous!
It's starting to look like I probably won't be doing this swap (because it's looking expensive and I'm feeling the economic pinch a little too). I'm still going to get the details together regarding what's required and interchangeability of parts etc.
I'd like to try 24"p props on the boat... I think that'll put it at 4800 rpm on a clean hull and medium load.

 

[magster65]

I don't know about your swap questions but I'm sitting here wondering what my 280DA would be like going 5-10mph faster. To me it already feels a little lite at near 50mph. Maybe a 290 would be different.

Feeling light... lol... reminds me of my buddies 22' Scarab (sistership pic). He pulled the 5.7 mag and put in a mail order 598 Chevy (one of these). That was the definition of light! It was ridiculously overpowered. 750 hp / 1.5 bravo 1 / 32" prop! You shoulda' heard this thing with the thru-hulls!! Anyways, we'd cruise at the hull speed... about 70 and hit the throttle and see how fast we could go before the chine walking forced us to slow down. We couldn't break the 100 mark but we did manage 90 and a bit... there was lots of motor left but the hull just wouldn't do it. I'll call those speed runs 'near death experiences'.
I think I'm desensitized now.

 

[six pack]

I'm not planning to do this but I was just pondering potential issues with replacing the 305 mpi short block with a 383 short block and using all the ignition and fuel systems off the 5.0... everything but the short block.
Physically it's a direct bolt it... no exhaust issues, mounting, I'm sure the fuel pumps are good... all the same bolt patterns from the 'vortec' years...
Would the ECM need a different calibration or a replacement from a 6.2 unit? What about the injectors... do they flow enough if the ECM mapping is rewritten?
I guess I could check and compare part numbers on the different engines. I'd like to know if anyone has done this sorta' thing.
Cheers!

Love to see what you come up with! Pondered that same question myself, why go to a 5.7 for an extra 40hp when you could go more, always heard how strong a 383 stroker chevy was, should work great in a boat, would worry about the fuel mapping for sure.