Can a 454 put out 650hp on 9.5:1 compression?
12-11-2007 | 10:58 PM
#21
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From: Tennessee
With really good head work and the right cam you can get there, but that is a lot to expect from an NA engine.
I would rather have one with a small blower and smaller cam so that the valve train would last a little longer.
Little young in this business, What do you guys think about my opinion?
I would rather have one with a small blower and smaller cam so that the valve train would last a little longer.
Little young in this business, What do you guys think about my opinion?
I'm of the opinion to build more cubic inches and keep the rpms down by putting together a package that works and makes your target horsepower with as little camshaft as possible. If you can't make the number that way, then give it some artificial atmosphere (that's a blower for those who don't understand)
12-11-2007 | 11:43 PM
#22
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From: Lake Conroe, TX.
I think you pretty much nailed it. Why put a GORILLA camshaft in there and spin it to the moon unless you have to. Those instances are rare, like in a limited class of racing. You can only use certain parts and do certain things, so you do what you have to in order to make the most power you can. That is a race motor that may or may not stay together. That is not what you want in the family cruiser.
I'm of the opinion to build more cubic inches and keep the rpms down by putting together a package that works and makes your target horsepower with as little camshaft as possible. If you can't make the number that way, then give it some artificial atmosphere (that's a blower for those who don't understand)
I'm of the opinion to build more cubic inches and keep the rpms down by putting together a package that works and makes your target horsepower with as little camshaft as possible. If you can't make the number that way, then give it some artificial atmosphere (that's a blower for those who don't understand)
Big power from large displacement is not automatic, but it is a lot easier.
A problem I have been coming up with in my calculations is keeping compresion down. How practical is it to open up the combustion chamber? Most open chamber heads are around 188-199cc. How big can you make the chamber on a normale iron or aluminum head? Is using a dished piston the most common way to go on a high boost engine, or are other things done?
I can get into the mid8's on a carb without geting crazy on the cam, but at that point it is time to start with blowers. I am contemplating my next experiments and want to start getting into 10-1271's.
12-12-2007 | 06:45 AM
#23
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From: Cleveland, Ohio
You can make the power, but will the engine idle? If you put enough lift and duration, a lot of things are possible, but what about the center line. Are you going to have a reversion problem.
With really good head work and the right cam you can get there, but that is a lot to expect from an NA engine.
I would rather have one with a small blower and smaller cam so that the valve train would last a little longer.
Little young in this business, What do you guys think about my opinion?
I have a little 468 that I built out of left over stuff in my shop that makes 9.5:1 that I use for experiments. I put a .560, 248 solid flat tappet cam in that I want to try out in a couple weeks when my Dyno gets here. Has ported 049 iron oval heads on it. I'll let you know what it makes, but I think it is going to be low 5's
With really good head work and the right cam you can get there, but that is a lot to expect from an NA engine.
I would rather have one with a small blower and smaller cam so that the valve train would last a little longer.
Little young in this business, What do you guys think about my opinion?
I have a little 468 that I built out of left over stuff in my shop that makes 9.5:1 that I use for experiments. I put a .560, 248 solid flat tappet cam in that I want to try out in a couple weeks when my Dyno gets here. Has ported 049 iron oval heads on it. I'll let you know what it makes, but I think it is going to be low 5's
12-12-2007 | 06:48 AM
#24
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From: Cleveland, Ohio
12-12-2007 | 08:28 AM
#25
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From: Dallas, TX
What is the exhaust system on these engines? The original Merc 420 cast iron exhaust rusted and leaked. If it was converted to the standard Gil wet exhaust, this would be another reason that the "in the boat" HP is more likely close to 500HP.
Another angle you might look at is performance. If this 38' boat still has the TRS drives, they would be on the edge at 650 HP....this Scarab would probably weigh 11,000+ lbs with crew and fuel.
Maybe a top speed in the high 60's to 70 MPH? My 30' Scarab with TRS's only ran about 70-72 MPH with 500 HP in 1988....pre-GPS so even that is suspect
Another angle you might look at is performance. If this 38' boat still has the TRS drives, they would be on the edge at 650 HP....this Scarab would probably weigh 11,000+ lbs with crew and fuel.
Maybe a top speed in the high 60's to 70 MPH? My 30' Scarab with TRS's only ran about 70-72 MPH with 500 HP in 1988....pre-GPS so even that is suspect
12-12-2007 | 08:59 AM
#26
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From: Tennessee
12-12-2007 | 12:00 PM
#27
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From: Lake Conroe, TX.
What is the exhaust system on these engines? The original Merc 420 cast iron exhaust rusted and leaked. If it was converted to the standard Gil wet exhaust, this would be another reason that the "in the boat" HP is more likely close to 500HP.
Another angle you might look at is performance. If this 38' boat still has the TRS drives, they would be on the edge at 650 HP....this Scarab would probably weigh 11,000+ lbs with crew and fuel.
Maybe a top speed in the high 60's to 70 MPH? My 30' Scarab with TRS's only ran about 70-72 MPH with 500 HP in 1988....pre-GPS so even that is suspect
Another angle you might look at is performance. If this 38' boat still has the TRS drives, they would be on the edge at 650 HP....this Scarab would probably weigh 11,000+ lbs with crew and fuel.
Maybe a top speed in the high 60's to 70 MPH? My 30' Scarab with TRS's only ran about 70-72 MPH with 500 HP in 1988....pre-GPS so even that is suspect
12-13-2007 | 10:45 AM
#30
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From: Lake Conroe, TX.
Thye are great though. I use them at every oportunity. I don;t see why you can't go 200 hours or so between having heads re worked or checked, if they are set up right initially.
Some of these other guys can probably give you some better insight.
