What normally aspirated engine has highest power?
 

Does anyone have a recent updated list regarding what the various commercially available N/A engineS produce, power-wise, at the prop?

Thanks!

my guess, The Merc Racing:
860hp
565hp
520hp

https://www.mercuryracing.com/engines/sterndrives.html

Is there a reason why you would want to make big power NA? There is a reason why Merc put superchargers on anything over 525hp, until these 2 latest offerings. I suspect the 860 is well over $100K. I had a Nordic with a pair of Pfaff 700s in it that were NA and I built a pair of 700hp 540s for an Eliminator cat that were NA, but is about the top end of a NA engine that is going to be boat friendly.

I totally wrecked the title of this thread...sorry.

Still looking to repower my 252 Baja someday, replacing the stock 454 with something with more oomph...but still using as much of the same setup as possible with what I already have.
'Black' engines then - 502 Mag MPI has...415 hp at the crank? 496 Mag H.O. has 425 hp?
'Blue' engines - 500 EFI has 500 at the crank? What other 502 block based engines will 'fit' for me?

Thanks again

Gen V and VI can be built to near 600cui and make 1000hp N/A. Just takes cubic dollars.

Most common sizes on here that we see are 540's, 565's, 572's I believe all those share architecture with the 502 block and mate up to all the standard big block parts....

I'm no expert though, but I do have 565's and stayed in a holiday inn once

I think you need to be a bit more specific. If I remember, you have a 454 MAG EFI, correct? And you're looking to keep it fuel injected, re-use as many of your stock parts as possible on a higher HP engine while still keeping the Bravo 1 outdrive. Am I correct?

572 is probably the biggest practical stroker however the most common is a 540 cubic inch motor . 502 block with a 4.25" stroke with a 4.466" bore . A mild build will generate an easy 500 hp, however a motor is just part of a bigger system. The 502MPI is limiting on the induction side and the factory exhaust manifolds are restrictive. Next what about the outdrive. Im in the same spot you are , I have a 272 that had a bad 502 that is getting a mild 540 . One concern is the ability of the Bravo 1 to last and the stock steering to keep the boat pointed straight without adding hydrologic steering. The headers/ exhaust is no mystery, the intake system needs more flow from either a big carb and matching intake or aftermarket fuel injection. Oh yea the fuel system and keeping the oil cool and clean are two more items that come to mind.
there use to be a popular saying "its not about how fast you want to go but how much do you want to spend "
And insurance, idle quality , intended use , return on investment........

Repowering your boat will give you a boat worth the same as it does today running....anything Merc under 575 will be NA (600SC is still packaged with Bravo XR for reference) and a Merc Racing 525 can be warmed up to more hp... how big of hp directly correlates to how fast you break drives

Double Post

The math on that works out to a 532", 532.6" actually.
4.5" bore x 4.25" stroke = 540.7", otherwise a 540.

Thanks, though it's just a 7.4 MPI, not a Mag engine.

Thanks for all the other replies, too...great information and answers my question.

I've got a couple of people interested in my 208 Islander, the thought is to use those funds for the re-power project. It's not something I HAVE to do, more of a want... and there is certainly the argument to just let it be and enjoy.
Is it me or are used engines just nearly impossible to find now? Seems like they were littering the place a couple of years ago.

Carnut pretty much said what I was going to. However, I thought you had the 454 MAG?

Your 7.4L I think is 330 HP., So a 502 MAG is a nice upgrade (415 HP) but prob not worth the hassle of exchanging everything for a mild boost in performance.

You really need to look for a HP 500 in my opinion to make it worth your while. It would be the upper limit of the bravo 1 out drive capabilities and give you a fair amount of performance.

Yes, engines are much harder to come by lately.

A 502 mag has lots of options for future improvement..the 7.4...not so much....

Yeah...a 500EFI is my dream engine for this boat. Was actually a factory option.
I'm keeping my eyes open. Like I said before, it's a want, not a need so I can be patient...

(This is what I tell myself whenever I get frustrated!)

Why limit yourself to such low horsepower?

Not wanting to replace out drives too.. (at least that was my reason. I cannot speak for Baja)

This is true if you're looking to upgrade in stages.

2 just sold in the swap shop for $25k for the pair. I was watching 1 on Ebay earlier on this winter. Guy was asking around $11k.for 1 with a little over 400 hrs on it. I opted to pass because they recommend rebuild at 500 hrs.

Plus I would had to replace the computer along with the engine. (Mine has MEFI 1 and believe the 500 EFI is MEFI 3? so more cost plus changing wiring harness).

How fast do you want to go in a Baja? No offense...anything above 80-85 would scare me.

Wanting to stay with the 'plug and play' concept as much as possible, i.e. take out old engine, drop in new, plug into existing harness, hook up fuel and exhaust and go. And stay around $15K for project. Boat runs ~54 mph now, I'd be happy with 62. My 208 will run high 60s so, it's that speed I am missing...but the 208 just isn't able to handle rough conditions very well with only a 17 degree deadrise, hence the purchase of the 252.

If that's all you're looking for, then maybe a 502 would be good for you?.

My Cobalt 252 with the 502 MAG EFI (had Hardin Seaward exhaust with good FA only) getting me 63 MPH (GPS reading) with it weighing 4500 lbs. dry..

I can't see a reason your Baja couldn't do that or better with the same engine since I would guess you have a faster hull.

I would venture to say $7-8k for a used 502. Have the fuel injectors flowed/cleaned. Do a complete tune up. Remove and replace engine. Prob less than $10k total.

Sell your 7.4 MPI engine for $4-5k? You get what you want for a lot less than your $15k

This is exactly what I just did to justify the HP 500 engine I had installed.

Thanks, xlint89.

We're in the same ballpark weight-wise, I've seen numbers between 4,400 and 4,700 listed for the 'dry weight'. I know the boat and trailer are 6,870 combined but I've never weighed just the trailer.

Of course like most, I desire as high of speed as possible given the parameters I've set. 62 would be sort of a 'minimum' to make it worth while/put a smile on my face. 64 - 66 would be sweet, but I'm a realist. The 252 is extremely stable and tracks/rides SO well...to me it just begs for big power. As mentioned before, an HP500 EFI was the biggest factory power available.
My 208 is faster but is such a handful at speeds around 65 mph unless the water is really smooth. My wife HATED riding in that boat at speed or in rough conditions...and you know what they say, "happy wife, happy life"..

What drive do you have on your boat. I’m assuming it was Mercruiser.

Yes sir. 1.50 Bravo 1 Mirage plus 23 prop turning 5200 RPM

As I stated in the other thread, I was looking at the Baja 252 and the Cobalt 252. Found the Cobalt with the 502 and bought it.

For me the criteria was (upgrading the engine) max HP I could reliably run with the Bravo 1 and not have to add hydraulic steering. (keeping it under 70 MPH) So around 500 HP was what I was shooting for.

Not sure why you're so hung up on trying to transfer as many parts from the 7.4L to the new engine? I assume to keep cost down, but they are not performance oriented. And you're looking to gain speed. Sell your entire engine as a drop in package and install the new one. In reality, if you do find a 500 EFI it came with CMI E top headers, so your cast iron manifolds would be a major step backwards in performance and weight..

I am NOT wanting to transfer ANY parts...sorry if I misrepresented this. I've got a couple of friends who'd like to buy the 454 from me if/when I do this swap so...the only real parts that might come on/off would be the exhaust. And from what I can tell (and has been discussed some before), the Corsa Quick and Quiet exhaust won't work on the HP500, but WOULD on the 502. The ideal situation would be to find a nice, low hour 502 Mag MPI complete from top to bottom, and simply drop it in and hook up some hoses and wires.

Maybe I misunderstood when you said you wanted to plug and play harness, hook up fuel and exhaust systems? Sorry about that.

Not sure what the Corsa quick and quiet is, but I have the Captains Call diverters that work with the CMI E top headers. So it is possible to install them onto a HP 500 EFI. (I don't know if the EFI cam has as many reversion problems as the carb model though. So do your research if this appeals to you)

In the classifieds section there's a guy in TX that is selling a Marine Power 502 first gen FI 502. And a guy selling Mercruiser 502 EFI long blocks from Jersey in there too.

Just a FYI, I will be posting my 502 take out for sale soon.

Sweet! Thanks for the info. The Corsa exhaust is much like Captain's Call (see picture), in that you can choose thru-hull or thru-prop. After reading on the Corsa website about Quick and Quiet and Quick and Quiet II, I realize I do NOT have that system, as it has no selective ability...so my mistake on that.

https://cimg1.ibsrv.net/gimg/www.off...1b0c813643.jpg

You got Captains Call.

I have CMI diverters that work with E top headers if you wanted to keep the selectable exhaust.

I was using the Hardin Seaward exhaust with the captains call on my boat

.

https://cimg5.ibsrv.net/gimg/www.off...32afa61f90.jpg
https://cimg7.ibsrv.net/gimg/www.off...b71167d444.jpg

So..and pardon my ignorance...it appears that the centerline height of your exhaust would be very similar to what is on my boat now? One of the requirements of a re-power project would be to NOT have to change the exhaust outlets through the transom.
Thanks for the correction on the Captain's Call. I purchased the boat late last year, had it on the water for just a few days and then winterized it...and it is 300 miles away from me in storage so...not familiar with it yet by any means and...not able to just go check on it, lol!
That's the 502 you are planning on pulling out?

You should have standard Bravo exhaust location. The same as my boat and many, many others.

That was the engine installed in the boat with the first gen FA and the Hardin Marine exhaust installed.

This is how it sits now, ready for sale.

https://cimg2.ibsrv.net/gimg/www.off...8ca979360a.jpg
https://cimg5.ibsrv.net/gimg/www.off...bd3f83b870.jpg
https://cimg7.ibsrv.net/gimg/www.off...ce2e8c336f.jpg

Just listed the engine
 

Edit

....and I just brought my 208 home from Table Rock Lake today...12 hour hell-run!...so I can sell it. Things might work out!
https://cimg2.ibsrv.net/gimg/www.off...941162e3e4.jpg

Bring it up to Cleveland, it will sell. Then drive home with a 502 cu in. ;)

Marina/Dealer I am taking it to for consignment has...ZERO...used boats for sale. Typically he has 15 - 20. It's crazy how few used boats are for sale (as discussed in other threads).