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Old 09-16-2012, 12:35 PM
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sbc hp rating ?

Just wandered if anyone could give me a second opinion on probable power output of the engine ive put togeather, Im thinking 330hp but would hope for a little more engine specs as follows


357 +40 sbc 2 bolt mains

iron eagle ss cast crank
stock conecting rods- arp studs
speed pro hypertectic flat top pistons 4 valve reliefs
cloyes roller timing chain
edelbrock 70cc e-street heads
crane 274h06 cam= 218 duration 450/450 lift 106 lobe seperation
comp cams magnum 1.52 roller tip rockers
edelbrock performer inlet
edelbrock 600cfm carb
block hugger headers, 2.5 outlet think 1.5 primaries

engine comes in at 9.2.1cr


Also could I make use of my exsisting 2" duel exhaust with cherry bombs set up, or should i step up to a 2.5" setup??
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Old 09-16-2012, 12:38 PM
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Hp

There are nice cheap software programs you can get that very accurately estimate HP, torque and lots more. They are simple and fun along with a great tool to help choose your components.
desk top dyno for one.
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Old 09-16-2012, 07:06 PM
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Its probably close to 330 hp.A 3 inch exhaust is great,a 2 1/2 inch exhaust with X pipe is good.If the pipes are mandrel bent thats a bonus.
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Old 09-17-2012, 10:02 AM
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The Edelbrock e-street heads are acutally pretty decent for a mild street motor. with a 106LSA the cam is going to make that engine have a decent lope even though the duration isn't that aggressive. I wouldn't go with the 2" exhaust but the 2.5" exhuast is just fine. It have been proven that 2.5" exhuast with madrel bends can flow enough for up to around 500hp. I'm not real sure where you got you compression ratio from because when i calculate out a 4.040" bore, 3.48" stroke, an estimated -5.5cc's recess for the flat top 4 vavle relief pistons, a 4.100" gasket, 70cc combustion chamber heads and a quench in the .040-.045" range I am coming up with 9.67:1. with this compression, the mild cam, and the decent heads i would say you are making 350-360hp and 380-390tq.
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Old 09-17-2012, 12:27 PM
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compression ratio is not so simple.

Without knowing the exact piston to deck height, the figure will be close but just a guess.
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Old 09-17-2012, 01:01 PM
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Quote:
Originally Posted by hcmengines View Post
Without knowing the exact piston to deck height, the figure will be close but just a guess.

at TDC i measured the piston to be 0.025 bellow the block face.
the pistons are 6cc dish & gasket compressed thickness im uncertain of, there victor rienz items,part of a standard top end set, so guessing 0.039-0.041

i got the cr figures from summit racings calculator,but a mid 9 cr is bang on perfect in my head.

Thanks for the advice on the exhausts, ill sell on the 2" cherry bombs & get some 2.5`s & pipes on the go.

I got hold of desktop dyno, & ran the numbers on there, which if i got the cam specs rite, "got a little confused at that point" but that made a peak of 358hp at 6k.
However from what ive read the valve springs on my heads will pos break at 5.5k
so will set 5k as my limmit for safteys sake.

Last edited by swompz; 09-17-2012 at 01:09 PM.
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Old 09-17-2012, 07:35 PM
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If the engine isn't already assembled then get rid of the standard .040" head gaskets, go look for a set in the .015-.025" range. this will put you in the optimal quench range. quench is the measurement of the piston @ TDC to the deck of the block (you said it was .025", which likely means that this block has never been decked) plus the thickness of the gasket (right now you have .040". these two numbers together give you .065" quench. Optimal quench is .038-.046". If you can find a .020-.025" head gasket (not shim) which victor renz makes a .025" that i have used without any problems, then your quench would be in the area of .045-.050" which is a lot better than .065".

with your current .040" gasket your compression is in the 9.1:1 range, which I would say would take off about 5-6% of the hp/tq numbers i told you (330-340hp). I based the 350-360hp numbers off of the 9.67:1 compression.
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