Adivanman

Speaking of speculating, I do think that the improvements between the 500 and 525 are worth more than 20 HP - try about 65 HP...

John B

If you put all the changes Mercury made to the 525 efi over the 500 efi into a computor program to determine hp, the new 525efi is closer to 575 than 525! I tried it.
JB

liquid lounge

Okay then, let's talk about sound...John B. , are you talking about the quality of the idle? If so, I've never thought the idle of the HP500EFI was quite up to par, although, I think that motor is very nice.

John B

It's not, but the 525 is HAIRY, from idle on up.

liquid lounge

Then my vote is for the header theory....although the new Motorola & MAP setup probably improves the idle somewhat. Just asking, what is the compression of the new motor? Thanks, Berg

Adivanman

Advertised compression ratio of the 525 is 8.75:1 - a whopping increase of....0 over the HP500EFI

liquid lounge

Wow, hardly seems worthwhile from a MFG.'s standpoint to upgrade to aluminun heads and not take advantage of a higher cr.

Adivanman- not doubting you, but where are you getting a 65hp increase? Seems like that kind of oomph puts this motor is too close to the 575efi sc!! This could be a marketing snafu that could upset some 575 owners!!!! How 'bout it Von Bongo?
Take Care, Berg

John B

Estimated gain over 500 efi

Heads 40 hp

Headers 15 hp

Throttle body 10 hp

Cam "what is it?" + something

Anyone else??

Adivanman

lounge - it is closer to 570HP and yes, that is encroaching on the 575SCi's numbers. Shouldn't upset the 575 owners much though - their engines say 575 right on them...

jdnca1

575's make more power than 575. Probably closer to 650.