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Old 02-21-2009, 08:43 PM
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Will this SBC combo make 400hp?

Hello whoever can answer this for me I would appreciate it. Fbird if you read this I know you can help me out. On camquest it says I will make around 420is hp and 430 ftlbs of torque. On compcams website with the same cam on a old set of dart torquer sr heads it make only 342 hp and that is a few less then the flat tappet version of the roller cam of mine. Can anyone give me a more accurate number or is camquest pretty accurate?

Ok just got all my parts to do my engine and here is my setup. 350 4 bolt main has been decked just .010 and is a new block with 4 inch bore.

Scat cast steel crank 3.480 with 4340 forged rods with Speed pro flattop pistons 4 valve relief with 1.560 compression height. Carb will be edelbrock performer 600cfm, intake edelbrock performer rpm, cam will be comp xtreme energy roller with 218/224 @ 50 with 497/502 lift and heads are world product sportsman II and will only be gasket matched to intake.

Compression will be around 9.1 with the 72cc chambers. Going in 96 s 10 with 2000 2200 rpm stall with 350 turbo. Thanks for help on guessing.
Eric
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Old 02-21-2009, 09:38 PM
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The 340 is way closer to what you'll see on a dyno.
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Old 02-21-2009, 09:49 PM
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comp cams has a program that you can download, the one they use, that you can pick all the different options you have on your car: heads, intake, exhaust, compression, ect... and it will give you estimated horsepower and torque.


http://compcams.com/downloads/register.asp

use this link and enter your info and it will let you download for free, fast and easy to use...
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Old 02-22-2009, 02:51 AM
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If you assemble it as you listed then yes the horsepower will be in the 340-360 range. The cr is too low low low. CR is your friend.
Why are u using just 9.1:1 cr. (72cc heads)??? Why are u useing a wimp 600cfm carb? You are crippling this combo.
Either use a 64cc sportsman II head or if the actual TDC piston/block deck clearance is now .018"+, mill your 72cc heads to 69cc and install with a .015" felpro 1094 gasket. 9.85:1 cr. I might even consider angle milling the heads on this one if you already own the 72cc heads, now.

If you were to spend a bit of time cleaning up the "out of the box" Sportsman II ports and port match the RPM manifold to the heads (critical) and get the cr up, near 10:1 by adjusting the chamber volume and gasket volume, you should see very close to 400hp. The sportsman II heads really wake up with a bit of hand port work on the as cast ports. Look at that big nasty as cast valve guide boss sitting in the bowl, restricting airflow.


The cam could be a bit bigger as well.
Call or email Comp Cams to get a custom grind hyd roller with high(er) valve lift (XFI Hyd roller lobes) and around 224 .050" duration and 108LSA. use 1.6 rocker arms. {reference comp cams #3015 XFI cam lobe}

Consider the W/P Sportsman II heads as "Diamonds in the rough."
The sportsman II heads need a bit of port cleanup and lots of net valve lift (.550"++).
(this is also very true for the S/R heads and the simular Dart S/S 165cc heads {good basic new HP castings- much better with a bit of detail work})


The engine dyno simulations programs like Camquest and desk top dyno will give inflated power results when you don't enter the true modeling varaibles.
Especially the carb CFM and cylinder head menu choices. EG: use the expected total engine airflow cfm consumption insead of the rated carb cfm. Think around 550-575 cfm (measured engine airflow consumption on the dyno) from a engine like this.
This motor needs a 750cfm carb also. A 600cfm carb is costing you at least 10HP on this build.

If you were to make all these improvments to your basic combo and dyno it, you should expect 400+dyno hp with very good low end torque for your mild stall converter. The power is there in the basic parts, but its up to you to do the required finish work to realize the power predicted by the various engine simulation programs.
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Last edited by F-BIRD'88; 02-22-2009 at 04:17 AM.
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Old 02-25-2009, 07:06 PM
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Hello Fbird thanks for the help. I have the 72 cc heads already but I cam get them milled to get to 69cc's. But what about my cam I was looking at the next level up extreme energy cam the 276hr wich has 224/230 @ 50 with 502/510 lift. I want to stay with the 1.5 ratio since I will already have a fortune in machine shop bills once I get the blocke decked and my rotating assembly balanced ec. Would the 276HR cam still be good in a daily driver and not make it do too much different then the previous cam but make the heads breath better and would this cam work ok being able to drive through town rush hour traffic and not get my motor all loaded up and not make it consume more fuel then the 262 cam? I am trying to find the balance as best as possible with out going oveboard. This will be my only vehicle I have to drive all the time so decent street manors are a must but want performance to go along with it with a nice lope at idle with being too much but more then stock smooth type idle. I hope you respond cause you have helped me select my stuff so far and I have taken all your advice. Thanks Eric
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Old 02-26-2009, 04:05 AM
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Buying 1.6 rockers instead of the 1.5 rockers does not increase your "machine shop bill".

If you want a better mousetrap, look at what I recomended and build it to spec.

Pick up the phone and call Comp Cams tech and show them what I refered you to. They will advise further and make you the right cam that takes full advantage of the ported Sportsman heads. The cost is little or no higher for a custom ground cam. The power difference is significant when you take care of these details. This is as big as you want to go with a 2200stall.

If you want a 340-360hp throw together, medioker motor then build it employing all your "Easy Button" choices.

Last edited by F-BIRD'88; 02-26-2009 at 04:12 AM.
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Old 02-26-2009, 06:27 PM
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Hey thanks for the comments but what I was meaning was I would have to get the pushrod holes elongated in order to use 1.6 rocker arms, at least that is whay is says with the papers that came with the heads.. I am going to get my heads milled down some and get my block decked as well to get more compression. Then I will call comp cams tech when I go to get my cam and ask them what they suggest on a custom grind and go from there. Thanks for help cheers.
Eric
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Old 02-26-2009, 06:38 PM
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when 1.6 rockers are used the push rod gets moved slightly towards the rocker stud.

On the sportsman heads the pushrod is guided by push rod guide plates.

There is a rather large hole in the head that the push rod passes through. Worst case situation the push rod pass thru hole may need to be elongated slightly towards the rocker arm stud (about .030") using a 5/16" rat tail file.
This can be done by hand using a broken 5/16" rat tail file in a drill.
You can do this yourself.
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Old 02-26-2009, 07:18 PM
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thanks for the tip. I don't know much about what to do yourself wise on cylinder heads. I am a rookie when it comes to engines and things you can do yourself wise.
Eric
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