refresh 500 hps
 

im at 340 hrs on hp 500s carb year 2000 and want to refreshin up in the spring. any ideas what all to replace and would like to build up about 50 hp. brand of parts to use and
hp build up ideas. currently have 1" spacers under carbs and carbs been re drilled and run msd boxes. i replaced the valve springs at 200 hrs.

thanks for any help

Re: refresh 500 hps
 

Only 50 hp?? You know I'd love to get my hands under those valve covers. I have a die grinder that loves to remove cast iron. :D With a good port job, 10.5 pistons and the right cam, how about 600 hp a peice? 90 mph and he want's more :rolleyes: I knew I liked you!!!

Re: refresh 500 hps
 

keep everything the same...good valve job, a bit more compression, and maybe a cam change...shoot for 580ish. that's about what a 525 conversion is.

ps...i have known race 500hp's to have that many hours on them and still go'n.

Re: refresh 500 hps
 

With a good intake, carb and our head work you will see 700+. Call or email me. Thanks Mike
[email protected]
570-956-2840

Re: refresh 500 hps
 

How much does a 200 hp head job and intake cost and what intake comes with it?

Re: refresh 500 hps
 

HEY MONKEY WHATS UP, NEED TO RULE THE RIVER( LOL)
YOU KNOW HOW IT IS NEVER FAST ENOUGH. :drink:


HEY JOE GOOD TO HEAR FROM YOU BOAT STILL WORKS GREAT ILL GIVE YOU A RING SOMETIME THIS SPRING WHEN IM READY TO REBUILD AND ALSO MAYBE WE CAN TALK ABOUT A LITTLE BOTTOM WORK ON THE HULL AS WELL.

THANKS RICK :drink:


THANKS TO ALL FOR THE INPUT

Re: refresh 500 hps
 

A 700+ hp, 500 ci engine will not be very user friendly.

Re: refresh 500 hps
 

Top End:
Have heads throughly gone through. Check and replace any gaulded valves. Retainers and locks are cheap and would just put new in. Have bowl work (porting) done on the intakes and exhaust. This is the best bang for the buck. Have shop do a nice 3 angle valve job. Keep intakes and carbs. I would check springs and replace if seat pressure is down more then 15%.

Middle:
Cam change with the bowl work will get you the power increase you want easily. New timing sets, double roller would be good, I would change the lifters out.. . .especially if the springs were real bad when changed at 200hrs.

Bottom:
Marine engines don't see much cylinder wear. If the P/W clearance is within factory specs I would hone and re ring. Polish crank and use new bearings.. Use stock Melling M77 and shim pressure spring .125".

Assemble with cometic head gaskets. Should give you a reliable 560HP

Re: refresh 500 hps
 

My advice."START NOW" don't wait.

Re: refresh 500 hps
 

In response to your question 800xcr how much $$. Our fully ported head jobs are 1200/ set, plus what ever hardware and valve components alond with machine work if any are needed. Intake of choice is a Merlin sing plane.

PatriYacht Our 700 hp engines are very user friendly. Due to the fact that they have a hydraulic roller valve train which is very reliable and requires minimal maintence.

Re: refresh 500 hps
 

10.5:1 comp. with holley dominator

Re: refresh 500 hps
 

500 ci, normally aspirated, 10.5, single 4 bbl on pump gas...... and 700 hp....


i really suggest that you guys get yourself a subscription to hot rod magazine. or go to the library and look at some back issues.

those guys are really pretty good and have put together a million combinations of big block normally aspirated motors ( and blower motors) and are generally honest and objective about the results and , more importantly , spend some time explaining the true engineering and science that goes into the decision making process during component selection...

now i know these aren't boat motors but realistically, hp is hp... and marine hp is no dif then terrestial hp... the curves and the ancillaries may differ slightly but the structure is structure and flow is flow.... physics and thermodynamics don't change when you step off your dock.

i am beginning to believe that the easter bunny may be the largest supplier of marine engines in the world.

Re: refresh 500 hps
 

rs:
You need to look up Linster and Excursion here on OSO. They rebdid the HP500 carbs in Excursion's 37AT and are around 565 hp now. They are running flawlessly. There are a couple posts on OSO about this build already.

Re: refresh 500 hps
 

StevesXM, I've been sitting back reading your posts thinking this guy has no idea that an opinion CAN be a little too over the top. You caught yourself once and made an apology, BUT, It is apparent that your ego can not be kept in check. There are a lot of people on here that DO know there stuff. So HOT ROD tells the truth huh? Well then, JUNE issue 1995, Dick Gazan built and dyno'd a 770 hp, (yes 770), 11.06 compression PUMP GAS motor. Don't assume that because you have a captive audience here that everyone is going to sit back and listen to your soapbox bullchit. I know, I know it's not 10.5 to 1, that must be why it made all that extra power..........Oh yea, it was 511 inches not 500 too.

Re: refresh 500 hps
 

P.S.----Check and Mate. Game over.

Re: refresh 500 hps
 

Mike11, thanks for the reply. However, I am still more than a little skeptical on your or anyone elses ability to be able to do enough work on the specific gm head of an HP 500 to be able to produce 700 HP with 10.5 CR and under 6000 rpms. Do you have a full dyno sheet you can post along with real world boat speeds (gps) before and after? Thanks

Re: refresh 500 hps
 

Mike, I'm not disputing, but how can you get that kind of power with a hydraulic roller? I thought you could only go to around .570 lift with a hydraulic roller. Does this only apply to GM hydraulic rollers?

Re: refresh 500 hps
 

nope... not ego and in no way suspect captive audience... but a reality check is in order periodically.... and if this guy is taking a 500 in motor at 10.5 : 1 w/ a single 4bbl on pump gas and making 700 hp.... well .... that's just amazing and nothing like that ever crossed my dyno ... ever... not in the hundreds of motors built by some incredibly clever and smart ( not to mention multiple championship winning ) guys and i did a bit of research on the web BEFORE i wrote that... figured , well been on the beach for a few years and maybe the earth spins backwards on its axis these days and i just haven't noticed.....

nope.... just about everywhere i looked, 500 in, single 4bbl motors, normally aspirated 10 to 1 more or less are all in the 575 to 600 hp range. there was the occassional ref to a 700 varient but could not find any specifics....anywhere... nor an uncorrected dyno sheet to back it up...

and it doesn't matter to me one bit if you want to believe the hype and bull**** from these guys. if it makes you feel better about yourself to have that dyno sheet in your pocket , knock yourself out. i'de rather have the real hp as opposed to the piece of paper. sounds to me like you are their kind of customer.

and no apology at all for THESE observations/ opinions

Re: refresh 500 hps
 

I guess you should have looked at HOT ROD, June 1995, Pg 44,46,47,48,49,and 50. 770 hp,664 ft lbs. Quote " Furthermore, the horsepower climbed steadily for a very usuable power curve that will be tire and drivetrain parts friendly in the car. Not bad at all for out of the box parts"

Re: refresh 500 hps
 

:evilb: :D :D :evilb:

Re: refresh 500 hps
 

ill look it up...and as soon as mike posts his specs , we'll see if its apples and apples.

see... told you to look in hot rod...and there it was

Re: refresh 500 hps
 

Merry Christmas Steve. :drink:

Re: refresh 500 hps
 

you too... really

if you can't mud wrestle with your friends over dyno numbers , what good is having friends at all ?

interesting thing i found while researching my own stuff... i.e looking for about 100 hp the " easy way "

looked at the procharger web site and they have a pretty interesting section about one of their competetors and the claims made in their advertising. flat out accuse them of being willfully misleading....

i , for one , think it is a very interesting topic...

Re: refresh 500 hps
 

700 reliable hp out of a 500hp...good luck!...that's just short of a SUPER CAT engine running 7600rpm...6200 rpm is about it on pump gas for a marine engine...then to run 700hp, your tq number is going to be out of hand...with a Bravo! :rolleyes:

Re: refresh 500 hps
 

The one absolute truth here is that you will definately have to rev the motor 6500 plus to get the horsepower. And yes it will take a healthy solid roller cam to do it. Which as we all know will take alot of valve spring pressure to control. To make big horsepower below 6000 rpm, you have to force the air in it, or have alot of cubes. You can build a bottom end that will spin 7000 all day long, but a $50 roller lifter going bad will ruin your summer in a hurry. 600 hp and reliable, very easy, 700 hp and truly reliable??? That depends on if you are willing to change lifters and springs every season, and dyno your motor to get the fuel right before you melt the valves out of it. :chimp:

Re: refresh 500 hps
 

ding ding ding.

and it really is that simple.... yes... you can ( for all intents and purposes make any hardware do anything for a VERY short time if you are so inclined... but to suggest 700 usable reliable, go to the gas dock and buy gas for it and run it around for a 250 hrs or so sort of hp out of a 500 inch, single 4bbl, 10.5 : 1 motor is quite a stretch for me...

thats 1.4 hp/ in and that is very very very good for a non pure racing, normally aspirated motor... something that you don't have to worry about having a spare in the truck every time you go out.

the power comes from the compression ratio ( and of course the total flow). either true mechanical or dynamic by virtue of forced induction. 10 : 1 is a very good number for pump gas and 10.5 is nudging the envelope and you need to have everything else correct... but what happens ( as smitty and other well know) is that when you pump the compression you risk melting the pistons ( detonation) so , naturally, the timing ends up retarded and the fuel ends up being too rich ( cooling rather than actually burning) to make the real numbers that you wanted in the first place.

can you actually make 700 hp from 500 in ? sure. it was never my contention otherwise ( altho im sure thats what it seemed) can you make 700 hp at 10.5/ single 4bbl normally aspirated on 87 octane pump gas in a manner that makes it a usable motor for real world application ? well...... all i am saying is that i have never seen any such thing. but i can be wrong and am well happy to be proved so. everything i learn today makes me better tommorow

Re: refresh 500 hps
 

Im doing this exact thing right now except leaving the bottom end alone. hoping for 570hp

Re: refresh 500 hps
 

and the heads were shaved .020 with .027 cometics to bring up the c/r a little