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Old 11-12-2013, 03:32 PM
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Hp/Tq calculations for top end kits

How can I figure out how many hp and torque my cam, heads, carb, and intake will produce? I was just curious what the formula was for matching parts when building a motor... For instance: I have a set of stock vortec heads (906) edelbrock performer rpm, 670 street avenger, and a Lunati Voodoo Hydraulic Flat Tappet Cam with 1.6 roller rockers.

Advertised Duration (Int/Exh): 256/262
Duration @ .050 (Int/Exh): 213/219
Gross Valve Lift (Int/Exh): .454/.468
LSA/ICL: 112/108
Valve Lash (Int/Exh): Hyd/Hyd
RPM Range: 1000-5500

I just need some formula's for motor building...

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Old 11-12-2013, 05:19 PM
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Quote:
Originally Posted by addictivewoodworks View Post
How can I figure out how many hp and torque my cam, heads, carb, and intake will produce? I was just curious what the formula was for matching parts when building a motor... For instance: I have a set of stock vortec heads (906) edelbrock performer rpm, 670 street avenger, and a Lunati Voodoo Hydraulic Flat Tappet Cam with 1.6 roller rockers.

Advertised Duration (Int/Exh): 256/262
Duration @ .050 (Int/Exh): 213/219
Gross Valve Lift (Int/Exh): .454/.468
LSA/ICL: 112/108
Valve Lash (Int/Exh): Hyd/Hyd
RPM Range: 1000-5500

I just need some formula's for motor building...
Desk top dyno, or experience with similar combos that have a 1/4 mile MPH and research.
Yours? 350ci? 9.5:1 comp? My guess would be 340hp with 15+HP left on the table by your Carb choice and possibly short lived cam life by the completely unneeded 1.6 rocker....
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Old 11-12-2013, 05:22 PM
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For the record, I like your combo for a street rod kinda deal minus the 1.6 rocker. For me I would use a 750 and throw a 2500 stall and 373 gear in a third Gen f-body and have fun.
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Old 11-12-2013, 05:24 PM
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What would be a better rocker ratio??. 1.5, or stock??. See thats my point, how do I know the proper components to mix match so I can have a good reliable motor with no premature wear do to wrong combo...
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Old 11-12-2013, 06:23 PM
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Quote:
Originally Posted by addictivewoodworks View Post
What would be a better rocker ratio??. 1.5, or stock??. See thats my point, how do I know the proper components to mix match so I can have a good reliable motor with no premature wear do to wrong combo...
Yep, it's going to take a lot of reading, a lot of talking with fellows who know what they're talking about and a lot of experience. I suggest you begin with learning about one component and go from there. For instance, this week you might learn all there is to know about rocker arms. Different motors, different mounts (stud mount, shaft mount), different ratios (1.5:1 is standard from the factory on Gen I Small Block Chevys), stamped steel, cast aluminum, billet aluminum, investment cast steel, self-aligning, roller tip, roller trunnion, long-slot, etc.
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Old 11-12-2013, 06:38 PM
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I agree guys. and I thank you so much for the advice.. I know NO ONE in my area that builds motors, or I don't have friends that build them that I can ask, so that's why I ask questions here. I'm the type that does it right the first time, I'm a very through person, that pays attention to detail, (must be the computer drafter and design in me). It's just hard because I hear one guy telling me that the 1.6 roller rockers are a good combo with my cam and heads, and then here you say that's to much rocker for my cam... I'm just trying to learn the right way so I don't look back in 20 years and say man I did it wrong that whole time... I did order david vizard how to build a small block on a budget, but I won't have it for a week or so... I just don't want to through stupid money away with parts that make no sense. I like everyone wants the best bang for my buck, I'm not caught up on name brands so I could care a less what brand it is, as long as it works in unison with the other parts/combo I use... So again PLEASE forgive me if I ask stupid questions, I'm just trying to learn, and if I'm asking that question, it's more then likely me doing research on what someone else told me....
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Old 11-12-2013, 06:41 PM
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bygddy, and techinspector1 Thank you very much…. (and of course everyone else)…You two have really been helping me out a lot, LOL, it’s always you two that answer all my question and for that I thank you…..
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Old 11-12-2013, 07:15 PM
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Quote:
Originally Posted by addictivewoodworks View Post
It's just hard because I hear one guy telling me that the 1.6 roller rockers are a good combo with my cam and heads, and then here you say that's to much rocker for my cam...
Long story short.......
Use 1.5 rockers on a street or street/strip motor.
Use 1.6 rockers on a competition motor where you need an additional 10-12 hp.
If a small block Chevy needed 1.6 rockers on the street, then Ed Cole would have specified them for the 1955 265 motor. Many times, you can go back and question why the factory engineers did something one way or the other and you can make sense out of it from that standpoint. Many times they did it to save a buck on the build and other times they did it for long service life and low noise.

There is absolutely no justification for using higher than stock ratios on a motor that you will not be doing routine maintenance on frequently. If you think the motor needs more lift, jack the static compression ratio up some and use more cam.

Take pity on those poor cam lobes too. The actual pressure between the cam lobe and the tiny little connection point on the lifter crown is ~250,000 lbs per square inch. Now, you come along and increase that pressure roughly 16% to 290,000 lbs per square inch. If you really and truly need the additional 10-12 hp that comes on the top end of the rpm range, that you use maybe 1% of the time on the street, then go ahead, knock yourself out. But be prepared for shorter service intervals.

.

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Old 11-12-2013, 08:23 PM
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I like to argue with Richard/you might learn something,or wrong thread?

Quote:
Originally Posted by techinspector1 View Post
Long story short.......
Use 1.5 rockers on a street or street/strip motor.
Use 1.6 rockers on a competition motor where you need an additional 10-12 hp.
If a small block Chevy needed 1.6 rockers on the street, then Ed Cole would have specified them for the 1955 265 motor. Many times, you can go back and question why the factory engineers did something one way or the other and you can make sense out of it from that standpoint. Many times they did it to save a buck on the build and other times they did it for long service life and low noise.

There is absolutely no justification for using higher than stock ratios on a motor that you will not be doing routine maintenance on frequently. If you think the motor needs more lift, jack the static compression ratio up some and use more cam.

A great

Take pity on those poor cam lobes too. The actual pressure between the cam lobe and the tiny little connection point on the lifter crown is ~250,000 lbs per square inch. Now, you come along and increase that pressure roughly 16% to 290,000 lbs per square inch. If you really and truly need the additional 10-12 hp that comes on the top end of the rpm range, that you use maybe 1% of the time on the street, then go ahead, knock yourself out. But be prepared for shorter service intervals.

.
A great mechanic and engine builder named Smokey Yunick built a 460 plus HP 302 sb back in the early 70s using stock GM parts
exceptions
his own design intake manifold and headers(something else?)
His biggest modification was changing the 1.5:1 stamped rockers to big block 1.7:1 stamped steel rockers. He had to remove the stock studs and relocate them to fit the higher ratio rockers.
The new "LS" engines use 1.7:1 rockers and the "LS427" uses 1.8:1 rockers.
The "LS" engine uses rocker shafts.
using high ratio rockers is more complicated than just bolting on 1.6 rockers out of a package
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Old 11-12-2013, 09:19 PM
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I agree. Everything has to work in unison with eachother. You change one thing and it effects something else.. its all about finding the perfect (or close to) balance. Thats why im asking questions. I don't want to build good engines, i want to build great motots...
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Old 11-12-2013, 09:24 PM
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to answer the original question;
I start with head flow numbers,this will tell me the potential horse power available,,,
IE; heads flowing 200 cfm intake side and 160 cfm exhaust side
"could" make 400 plus horse power (v-8) with an ideal combination of supporting parts.

The cam needs to lift the valves high enough and for long enough time to allow the heads to flow the 200 cfm and 160 cfm.
The air/fuel control system needs to flow enough for the heads to flow the rated cfm of the heads,
same for the exhaust system.

this is a basic formula to start,,,its not this simple
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Old 11-12-2013, 09:36 PM
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Quote:
Originally Posted by vinniekq2 View Post
A great mechanic and engine builder named Smokey Yunick built a 460 plus HP 302 sb back in the early 70s using stock GM parts
exceptions
his own design intake manifold and headers(something else?)
His biggest modification was changing the 1.5:1 stamped rockers to big block 1.7:1 stamped steel rockers. He had to remove the stock studs and relocate them to fit the higher ratio rockers.
The new "LS" engines use 1.7:1 rockers and the "LS427" uses 1.8:1 rockers.
The "LS" engine uses rocker shafts.
using high ratio rockers is more complicated than just bolting on 1.6 rockers out of a package
The old timers knew how to get it done! Here's a copy and paste for the "Jenkins" prepped Old reliable 68 camaro:

The engine is a correct Z/28 302 that has been built largely to the specifications it used in 1968. There’s an original 30-30 (Z/28) camshaft in the center of the block acting on a set of solid lifters, a pair of cast iron #3917291 cylinder heads (completely stock, no porting allowed), along with stock rocker arms and valve springs. The intake is a correct 302 aluminum intake, casting #3917610, topped by a Holley #4053, 780 CFM 4-barrel carburetor. Compression is around 11:1, and it currently generates right around 400 horsepower according to Jerry. Shocking that a 400 horsepower car could be a national champion, but when you can launch as hard as this one does (there are photos showing this small block car with its front wheels a foot in the air).You’ll also notice the twin groove pulleys that were designed to eliminate belt jumping at high speeds (this engines shift points are at 8200 RPM!).
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Old 11-12-2013, 09:38 PM
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Here's the link: Corvette Bronze 1968 Chevrolet Camaro Z/28 | RK Motors Charlotte | Collector and Classic Cars
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