5.0 mpi to 383 conversion thoughts?

[woodguy81]

Looking for ideas and concerns with this idea. I’ve got a pair of 5.0 mpi engines in my boat and want to go bigger. Looking at getting a pair of 383 stroker long blocks and swapping the mpi intake and all other parts over to the engines. Will the ecu work or would I need a new ecu for each? Can they be flashed and who does that? What other issues might I encounter? Mercruiser sells a 383 stroker so I know it’s possible.

 

[Scott Danforth]

you will need to get the ECM reprogrammed for the stroker motors.

since all the Small Block chevy motors are dimensionally identical from the 265 to the 400 cubic inch. yes, dropping in the 377 or 383 or even a 396 standard deck SBC is possible. if you can have the exhaust manifolds spread out just a tad, you can jump to a tall-deck motor and go up to 463 cubic inch small block.

However to keep the budget pocket-friendly, I would stick with a 377 or 383 standard deck

what drives do you have? if alpha drives, you may want to stick to a 350 or you will need to ease into the throttles

 

[woodguy81]

It’s got bravo 2 drives. No more height clearance for taller engines. They almost touch already. Lol. Where can I get the ecu flashed. The engine shop said they will run but not to their full potential with the current ecu.

 

[itsathepete]

Maybe someone else knows, but I wonder if the intake will be well suited for the larger displacement. Or maybe they all use the same one?

Edit just looked it up and part numbers appear to be the same

 

[Scott Danforth]

It’s got bravo 2 drives. No more height clearance for taller engines. They almost touch already. Lol. Where can I get the ecu flashed. The engine shop said they will run but not to their full potential with the current ecu.

there are only two places to get your ECU reflashed. been covered on the site. need to know which ECU you have. do a search.

 

[woodguy81]

there are only two places to get your ECU reflashed. been covered on the site. need to know which ECU you have. do a search.

Can you direct me to the places that can flash the ecu? Just getting costs together at this point.

 

[Scott Danforth]

Can you direct me to the places that can flash the ecu? Just getting costs together at this point.

OK, I will do the work for you.

here are the two options that I know still reflash

Hardin Marine - ECU Upgrades and Tuning

ECU Upgrades and Tuning

www.hardin-marine.com

Whipple Superchargers

Explore the legacy of Whipple Superchargers, a family-owned and operated powerhouse since 1987. Founded by the innovative Art Whipple in Fresno, CA, our journey from racing circuits to leading supercharger technology reflects a commitment to excellence. Experience the Whipple difference in drag...

whipplesuperchargers.com

Simons may or may not reflash anymore. you will have to call them (not email, however pick up the phone and call). https://www.simonperftech.com/products

 

[jimmbo]

Things are so much easier, when Carbs and Mechanical Advance Distributors are used, no iffy computer programs to fry an engine.

 

[Scott Danforth]

Things are so much easier, when Carbs and Mechanical Advance Distributors are used, no iffy computer programs to fry an engine.

and then you can also add more cam duration, and a larger intake plenum to boost mid-range torque.

 

[jimmbo]

Even switching from 1.5:1 to 1.6:1 rockers will complicate a reprogram

The hardest thing about Carbs and Mechanical Distributors, is making sure the guy buys USCG certified items. Same goes for the FI systems but a lot of Hot Rodders just ignore it cause, they are Special, and rules are for others, not them

 

[Scott Danforth]

Even switching from 1.5:1 to 1.6:1 rockers will complicate a reprogram

or staggering 1.52 on intake and 1.6 on exhaust

Also G.M. did a test on one of their 358 Nascar spec engines and ran ratio's 1.65 - 1.70 - 1.65 - 1.60 - 1.60 - 1.65 - 1.70 - 1.65
on each bank to achieve about a 40 horse increase.

 

[jimmbo]

1.52 on intake? Will idle very well, but run out of breath at about 2000

 

[Scott Danforth]

1.52 on intake? Will idle very well, but run out of breath at about 2000

Stock is 1.5:1. Not sure where you get your info. However 1.6 on exhaust and 1.5 on intake was common to bump midrange torque slightly without hindering top end.

 

[jimmbo]

I thought you were referring to the intake valve diameter, as 1.6 has been used on Exhaust
Me bad

 

[woodguy81]

OK, I will do the work for you.

here are the two options that I know still reflash

Hardin Marine - ECU Upgrades and Tuning

ECU Upgrades and Tuning

www.hardin-marine.com

Whipple Superchargers

Explore the legacy of Whipple Superchargers, a family-owned and operated powerhouse since 1987. Founded by the innovative Art Whipple in Fresno, CA, our journey from racing circuits to leading supercharger technology reflects a commitment to excellence. Experience the Whipple difference in drag...

whipplesuperchargers.com

Simons may or may not reflash anymore. you will have to call them (not email, however pick up the phone and call). https://www.simonperftech.com/products

Thanks for that. Still researching engine builders.

 

[Scott Danforth]

Thanks for that. Still researching engine builders.

Buy the parts and build it yourself for less moner and use better parts

GM block clearances for stroker crank

GM vortec heads (or upgrade to AFR aluminum)

SCAT rotating assembly

Comp or Crane cam, lifters, springs

Melling oil pump, core plugs

Clevite bearings

All new parts can be delivered to your house