Like Tree0Likes

Mercury 557 cu. in. naturally aspirated

Reply
Old 10-25-2008, 04:09 PM
  #1
Registered
Thread Starter
 
dkwestern's Avatar
 
Join Date: Mar 2002
Location: Lake St. Clair
My Boats: 33' Powerplay triple 2.5's
Posts: 2,973
Default Mercury 557 cu. in. naturally aspirated

Mercs used the 557 block for a long time now (900sc, 850/1075sci), would a 557ci N/A engine make sense? Basically make a 525efi using the bigger block, should make 700efi HP or so.

I realize they have the 700sci, and its been reliable but the 91 octane and the blower raise the initial price and operating cost and I would assume maintenance costs with the blower.

Reliability and maintenance may be better with the N/A along with 87 or 89 octane. Should be lighter and last longer between overhaul as well. I assume Torque should be close to the sci as well.

Just curious of others thoughts
dkwestern is offline  
Reply With Quote
Old 10-25-2008, 06:25 PM
  #2
jimdarr40
Guest
 
Posts: n/a
Default

would be a very expensive 700hp motor, just buy an Ilmor, lightweight, 2 year warranty, tons of torque, runs on 89 octane, n/a hard to beat
 
Reply With Quote
Old 10-25-2008, 08:00 PM
  #3
Registered
 
Brad Zastrow's Avatar
 
Join Date: Jun 2001
Location: McHenry, Illinois
Posts: 2,244
Default

Ateco Engines make a 540 CI N/A that will make 700hp carb or EFI. I think it makes perfect sense. However you will need to run premium gas as it will have higher compression to make that kind of power. I have talked to him about building 598 CI that should be around 750-800 hp.
Brad Zastrow is offline  
Reply With Quote
Old 10-25-2008, 08:03 PM
  #4
RHC
Registered
 
RHC's Avatar
 
Join Date: Oct 2002
Location: Sandusky Bay
Posts: 1,375
Default

alum heads and back the timing down a bit and big cubic inches and they make a lot of sense !

RHC
RHC is offline  
Reply With Quote
Old 10-26-2008, 12:58 AM
  #5
Registered
 
Join Date: Jan 2004
Location: Tennessee
Posts: 4,452
Default

Probably 95% of the engines I build are 598 ci. I love the bigger inch engines since they are very torquey. If you take a NA engine that makes 1.25 hp/ci, then it stands to reason that the more inches you have, the more power you will make.
A 557 ci engine at approx. 10:1 will make 700-725 hp with ease at about 5300-5400 rpm. You could make more than that, but you will have to spin it harder and have enough cam to make it pull to about 6000 rpm. You will obviously need 93 octane. If you want to run 87 or 91, it will cost you some power since you will need to lower the static compression.
If you are going to build a 557 like Merc., you will have to buy a 4.375 stroke crank. If you are going to do that, you might as well just buy a 4.5" stroke crank and do more inches. The 2 cranks are probably the same price, and the 4.5" crank is probably easier to find. Let me know if I can help in any way or if you just have some questions.
Eddie
Young Performance is offline  
Reply With Quote
Old 10-26-2008, 11:52 AM
  #6
S.O.B (single O/B) now
Platinum Member
 
t500hps's Avatar
 
Join Date: Sep 2004
Location: Richmond VA
Posts: 7,921
Default

If your thinking of putting a bigger bottom end but still using the stock 525 intake,etc....forget it. You'll never get enough air through it unless you do alot of port work to open up the plenum/intake.
t500hps is offline  
Reply With Quote
Old 10-26-2008, 12:38 PM
  #7
Registered
 
Join Date: Jan 2004
Location: Tennessee
Posts: 4,452
Default

Quote:
Originally Posted by t500hps View Post
If your thinking of putting a bigger bottom end but still using the stock 525 intake,etc....forget it. You'll never get enough air through it unless you do alot of port work to open up the plenum/intake.
Agreed.
Young Performance is offline  
Reply With Quote
Old 10-26-2008, 03:13 PM
  #8
S.O.B (single O/B) now
Platinum Member
 
t500hps's Avatar
 
Join Date: Sep 2004
Location: Richmond VA
Posts: 7,921
Default

and BTW: I made 540's out of 500EFI's. At 9.75 compression we were only able to get 630HP (fully dressed on a dyno) out of them. I'm told a good carb set-up could have made approx 30-35 more because I need more air.
t500hps is offline  
Reply With Quote
Reply

Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
IRONMAN
General Q & A
27
10-11-2008 12:04 PM
fast22
General Q & A
21
04-22-2008 12:25 PM
drypipetiger
General Boating Discussion
99
12-31-2006 10:37 AM



Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -5. The time now is 02:14 PM.


Copyright 2011 OffShoreOnly. All rights reserved.