SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: metalmulisha5006 on April 25, 2015, 09:23:12 PM
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454 std bore
10.5 compression with 119 cc
117cc chamber
781 ovals
2.25 intake 1.88 exhaust
Heavily ported
Edelbrock street tunnel ram
Two 750 double pumpers
Comp roller rockers
Pro billet distributor digital 6al ignition
Bassett headers
The cam I have layin on the parts shelf is a comp 310b
Solid lift
Intake centerline 108
Lobe separation 108
Duration @.50
Int.270
Ex.276
Lift
Int. 638
Ex. 631
Hull is an 18ft bubbledeck
So has anyone ran this cam or have any better suggestion I have Hyd roller cam jus don't have the lifters or springs for it..jus rdy Togo boating and tired of the sbc 355
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Wow, the intake valve closes 83-degrees ABDC.
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=464&sb=0
I think your dynamic compression ratio might end up a little low. I think the cross-sectional area of those heads might be a little small to get it to RPM up to where that cam will want to make power.
What impeller will you be running? You will need a small impeller to allow the engine to spin the RPM. Am I understanding correctly that you are changing from a small block?
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Bronze b impeller
Yes the 355 is alrdy gone spun the b impeller 51-5200 rpm
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If you use this cam I'd recommend running your headers dry. The 108 lobe separation will likely cause reversion issues.
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This is the Hyd roller I have... Just need the lifters and springs would this be a better choice
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With 96-degrees of overlap, reversion definitely is going to be an issue. What Bassetts do you have?
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The hydraulic roller is a lot more realistic choice. Do you know the ratings for the springs you have now?
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Not really worried about runnin water...never have been able too
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There the springs for the comp cam
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In an attempt to put things into perspective, your little mouse was putting out about 375 horsepower spinning a B impeller 5100 RPM.
The hydraulic roller you have, with 233-degrees duration @ .050 will put your 454's peak power in the low to mid 6K RPM range. You will need a minimum of 575 horsepower to turn that B impeller 6K and over 700 horsepower to spin it 6400.
In contrast, spinning that B impeller 7200 RPM with the mechanical flat will require 1000 horsepower. The pump will stall the engine long before it reaches peak power.
Depending on how your heads are ported, those ports will stall by .700 lift. Any lift less than that is horsepower left on the table. In other words, how much horsepower an engine makes is directly related to valve lift. Valve timing influences the power at each RPM point. Lobe separation angle (LSA) is simply a number calculated from valve opening and closing points, however I am a fan of tight LSAs. Keith is right, the 108 LSA of the mechanical flat will result in reversion but it is really the 96-degrees of overlap. Reducing the duration with the same lobe profile, while retaining the same LSA, will reduce overlap and potential for reversion. IMHO, a 108 LSA really makes an engine pop hard.
Having a 100ci advantage over the SBC, the 454 will produce more torque at every RPM. Cutting down the impeller to match the pump to the power curve of the engine will soften the launch on the initial hit, meaning the pump will burn out until enough water is being fed to the impeller so that it can pull the engine down and absorb all power being produced. I would definitely recommend an inducer and loader.
Not knowing what your heads flow, but assuming no damage was done in the porting process; I would estimate that you could get into the 550+/- horsepower range, depending on your actual head flow numbers.
My suggestions:
1.) Proceed with the hydraulic roller installed straight up. You will need to run good fuel.
2.) Have the mechanical flat reground with less duration, but try not to sacrifice lift.
3.) Run the mechanical and let the pump stall it wherever it may. I would try pushing the limits with advancing the cam timing to get more RPM. MAKE SURE YOU CHECK YOUR PISTON TO VALVE CLEARANCE!!! The intake valve will be the problem side. The more you advance the cam, the less clearance you will have.
Some final thoughts; I would definitely run a ball valve before the Bassett valve. Octane requirements for the mechanical cam will be much less as the dynamic compression ratio will be low as the piston is damn near half-way up the bore before the intake valve closes. Hydraulic lifters are expensive. If you hate running valves, go with the hydraulic roller.
Good luck,
Joe
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Wow thanks for the input best info I've received...I'm jus gonna buy the lifters and go with it...if I could run around 65 + mph I'll be happy
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Find out what the spring rates are for the springs you have now. Discuss your findings with the grinder of your hydraulic roller to see if they are compatible
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Yea they will work...I hope I pick up mph spending all this. $$ switching to a big block