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View Full Version : to super charge or not to super charge?



customan
05-24-2004, 04:54 PM
im thinking of super charging my 22 classic 496 ho , ive read alot about it and of corse the manufacturers say no problems !but im looking for people that have installed them and there opinions , the pros & cons after instalation please include brand of charger and psi that u installed thanks!

ChromeGorilla
05-24-2004, 05:05 PM
I was thinkin bout doin the same once my warranty ran out. I found that the OSO (OffshoreOnly) forums have many threads discussing superchargeing a 496HO. Alot of those guys have blown boats. I did a search in those forums and there was like 4 pages worth of threads on that subject. Each had in depth discussions on the subject. Check it out.

OSO (http://www.offshoreonly.com)

Barry Phillips
05-24-2004, 05:30 PM
The best kit I've read about is the Wipple, because it was co- developed with Mercruiser, so it comes with a new chip for the CPU. 5 to 7 Lbs of boost will yield 590 hp on the 496 HO. There is a great comparison between Wipple and Pro Charger in a past issue of Power Boat. Adding that much HP you need to think about your Bravo, which in your case is rated at 450 HP. Than I would think about external hydraulic steering and prop testing.

ChromeGorilla
05-24-2004, 06:08 PM
I read a post in OSO from Whipples tech guy and he said you actually mail them your ecu and they flash it with the new program and send it back.

MR MAGOO
05-24-2004, 07:35 PM
I just pulled a blown up 496 out of a friends boat. It lasted 3 hrs.

In my opinion, the 496 does not lend itself well to supercharging.

If you put a blower on the 496 you will have rods in the bilge :bawling:

gcarter
05-24-2004, 07:52 PM
How out a large stroker instead. You get the same horsepower without the hand grenade effect!

George

MOP
05-24-2004, 11:17 PM
If you do go for it, go for the expense of a good rotating assembly now rather than later.

rayjay
05-25-2004, 07:31 AM
How out a large stroker instead. You get the same horsepower without the hand grenade effect!

The 496 already has about the longest stroke, 4.37", you can put in a low deck BBC and still have a reasonable length rod. It is based on a stroked 454 not a bored 454 like the 502.

rayjay

gcarter
05-25-2004, 08:23 AM
Thanks for the info Rayjay. I'm not all that versed on BBC's. If you want a really large engine, what is the best way to accomplish it? I'm talking about 600 to 700 inches.

George

rayjay
05-25-2004, 10:09 AM
If you want a really large engine, what is the best way to accomplish it? I'm talking about 600 to 700 inches. - George

I have friends who think anything under 500 is a small block. They are the "experts", as I am sure some other members on this registry are. I can pass on what I have been told and have seen for myself, plus what I am going to do.

Number one, to get over 550 ci you really need to go to a tall deck block to have room for decent length rods. There are the regular or low deck 9.8" block and the tall deck or 10.2" block available from Chevy or a number of aftermarket sources. There was also a 10" variant, cast in AL/Silicon alloy, used in Can Am racing many years ago. But that is extremely rare and unique, plus it it really limited to around 500 ci.

10.2" blocks with stock cam location can go out to around 650 ci based on bore and the largest stroke that will fit. There are tall deck blocks and even taller blocks (>10.2") with higher cam locations and splayed pan mounting points that can go further in stroke than 4.75 but are still limited in bore. I have heard of a taller deck block that spreads the bore centers for an even bigger bore potential. But the cost of the reciprocating assembly makes this an impractical solution for anything less than take no prisoners all out racing. If you are rich enough to even consider running one of these, buy a boat that runs more engines. You'll get more out of it for the same amount of money.

Engines above 632 can cause rod length problems. In a 10.2 block a 632 (4.6 bore x 4.75 stroke) commonly uses a 6.7 rod for a rod:stroke ratio of 1.489:1. This will work and have a decent life provided you keep piston speed down by keeping the rpm's down. Generally, the longer the stroke the greater the piston speed at any rpm and the greater the rod:stroke ratio you would like to see for better power and longer engine life. Just increasing the rod length is not always a viable option as the piston pin starts to get close to or even goes into the lower oil ring. There are 347 SBF kits that use a slightly shorter rod. The kit with the longer rod put the pin behind the lowest ring causing oil consumption problems for regular use. For the track, revs and long rods are where it's at and you will live with the oil consumption problem. Something you really can't do unless you are racing and only care about the engine lasting to the end of the race.

I am starting with a good Gen VI 502 block which came with the boat. Next step will be a 4.25 or 4.375 stroke crank using 6.385 rods as opposed to the stock 4.0 stroke with 6.185 rods. These are about the longest rods you can easily get and fit into a regular deck BBC. I could go to an aftermarket tall deck block, but the cost of the block plus special intake manifold or manifold spacers start to be more than the cost of a supercharger. So from a cost effectiveness point of view I will probably just add a supercharger at some point if I need more power. I haven't made a decision about carb or EFI yet. I already have an AS&M BBC Marine EFI I was going to use on another engine I was building so I may use that and figure out the CU and OX Sensors for it.

If I was starting from scratch, I would definitely start with a tall deck block as the initial cost is only a few dollars more (if any additional at all) than a regular deck block and the reciprocating assemblies with really long rods are not that much more either. There are now aftermarket heads for the 496 so I would look at running them as soon as there is a block they will fit on. By then there will also be upgraded intakes available. Even without the new 496 style heads a 632 would make more power than just about anybody would want, or even use. A dual Whipple 632 with 496 style heads.. YEAH! Now we're back to talking some real power!! :outtahere

Remember this is only the beginning of a chain reaction. When I road raced a car I finally got the engine really singing, then the clutch started to not hold. Fixed the clutch and then the trans started to give me trouble when shifting. Fixed the trans and then the rear end posi started to not hold so I went to a locker. Fixed the rear and the rear suspension had to be modified to work. Now that the rear end worked I could use more power which made the clutch blow....

rayjay

hottub
05-25-2004, 11:24 AM
Anybody know anything about replacing the heads? Been intrigued by the following site......

http://www.raylarengine.com/

Seems safer than supercharging, and no reprogram of the ecu.

gcarter
05-25-2004, 11:32 AM
Yeah, you're right about the piston speed. A 4.75 strok is 3562 FPS @ 4500 RPM! That's kind of pushing it for longevity. There comes a time when more cylinders are useful. A V-10 or V-12 would really fill the bill.
As usual, there are no simple solutions.
Thanks for the info;
George

gcarter
05-25-2004, 11:37 AM
Anybody know anything about replacing the heads? Been intrigued by the following site......

http://www.raylarengine.com/

Seems safer than supercharging, and no reprogram of the ecu.
Is that $2650.00 for "ONE" head?

George....out of my price range!

Rootsy
05-25-2004, 11:37 AM
geeezus what are you boys trying to duplicate??? 1200 sterlings????

actually i know about jack and squat when it comes to PARTICULARS of the BBC... i have just never gotten into them... i've always been a mouse motor and sbf guy...

with that said.. i am kinda boggled taht you can ACTUALLY bolt an LS1 style head on a traditional BBC... but as i said.. what the hell do i know? not much in this case...

JR - crawling back into my mouse hole...

rayjay
05-25-2004, 12:26 PM
Yeah, you're right about the piston speed. A 4.75 strok is 3562 FPS @ 4500 RPM! That's kind of pushing it for longevity. There comes a time when more cylinders are useful. A V-10 or V-12 would really fill the bill....George

The piston speed is not the whole story. With better metallurgy we have pistons that fit better after warming up and are lighter yet stronger, plus much better rings that do not chatter. Acceptable piston speeds for a decent life have gone up provided longer rods with better dwell are used. It isn't just the speed that hurts the piston, it is the stopping and changing direction at each end of the stroke that does it. The old mass times velocity squared. Lighter mass helps, but it does not effect the piston as much as the speed. A longer rod softens (for lack of a better non-engineering word) the blow the piston, pin, rod, and crank take by giving the piston more degrees of crank movement to change direction, a greater dwell time. It's a combination of piston speed and dwell time. If you increase the dwell time the engine can tolerate (among other things) greater piston speeds. I remember when 3200 fps was considered the max reasonable piston speed to stick with for reasonable engine life, then 3300 fps and 3500 fps etc.. Now it is much higher provided a rod:stroke ratio gets up near 1.6 or 1.7:1 or more. My friend's wife's car with the 632 rarely sees over 39 - 4200 rpm as it has over 600 lb/ft of torque at the rear wheels from 2000 rpm on up. I saw this engine run on a dyno years ago and told BigG about it. That was long before it had the right combination of intake and cam and wasn't even dialed in. It made more torque just off idle than most econo boxes made at full tilt. Just keep it under 5000 rpm and prop accordingly.

Ryan Falconer did a V-12 based on the SBC and I think Thunder Engines does a BBC based V-12 for race planes. But wait to you see what the block and crank go for!! :splat:

With new engines such as the Chrysler and Ford V-10's and possibly a V-12 or V-16 from GM who knows what will be available in the future. Right now looking at cost / power / weight a tall block BBC type engine really looks pretty effective.


As usual, there are no simple solutions.
Thanks for the info; George

Amen Brother, Amen.

This is Brother RJ from the Church of Greater Power signing off. And, remember out motto's, "if more is better too much is just right", and "there's no such thing as too much power, just mis-applied".

rayjay

customan
05-25-2004, 06:38 PM
i looked on offshore only posts for info . i read some of the stuff . it seems that most had computer code problems that required them to send the box back a few times but once it was squared away they had good gains speed hps but, not many had alot of hours clocked to determine reliability .the idea is bolt on power ! every engine builder has there own formulas block ,crank ,pistons,heads ext. I can buy a hipo motor from any # of builders to get the same hp without a blower but my past experiance with cars and Vtwin motorcycles that ive built bored&stroked cam ext. left them problematic and unreliable a loss here for a gain their kind sh!*t i guess the wipple & procharger ads are selling bolt on power thats to good to be true and u no what they say! thanks for the input. I just havent herd enough good from every day boaters all i want is a biger gun for the gun fight stuffed in my 22 classic holster thanks again

BigGrizzly
05-25-2004, 09:07 PM
Just let me jump in here since I have a blown 502 with a procharger and my som has w 454 with a Wipple. Mine is carbureted, my son's is injected. Wipple never got it right. The first two tines the boat wouldn't run. The kid can build a motor- Wipple used every excuse in the world Finaly it came bacl sort of close. he took it down to orleans and had Mark Bose fix it. Wipple took two to Donzi and couldn't get them running right Steve Simonf traded them to hussler for two stock HP500. The unit is a nice looking unit and well done. BTW Garry Grimes has one for a 502 injected motor $200 under Dealer net, Mine is over 250 hours old. Truth is you can build a 570 or 640 with the same HP but the torque will be lower. On the Dyno I have 690+ HP but at 3977rpms I have 700 lbs of torque. At the same horspower yhe bigger motor habe less than that by 50 lbs. Also remember this is the biginning Now comes steering then a broken drive. I am not going to spit out number- you gys have them and they are pretty close. One more thing in the OSO post they always talk of black carbon on the stern, mine doesn't have this. Why ---because It is tuned correctly. Black transomes lead to premature engine failure due to oil dilution. Also you will find that Procharger only fixex the ecu on the first try. The 496 does have a supercharger problem. after 2002 the heat exchanger is smaller. Merc did a cost down on the engines