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Intake Runners!!! HELP!!!

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Intake Runners!!! HELP!!!

Postby chevyman18 » Thu Feb 07, 2008 3:06 am

I am building a mainly street driven 350. what i am having trouble with, is deciding on the intake runner size. i have heard that 200cc is too big for a 350, i have also heard it is perfect for a 350. on the other end, i have heard go with a smaller intake, like a 170, it will be perfect for your motor, then again i have heard its too small for my build. here is my set up, and hopefully i can get some answers on here! any info at this point can only help me, looking to get around 400hp and some good TQ at the flywheel. thanks!

(brand new) stock gm crate 290hp/350 short block
Rebuilt th350 w.2400 stall converter.
Lunati cam 268-276 dur, 227-233 dur @ .050 .487-.504 lift.
edelbrock perf rpm intake
holley 750cfm

The heads I am looking at are either Dart Iron Eagle Platinum 64cc 200cc, or Edelbrock Performer RPM 64cc 170cc. Also, is there anything I should know about aluminum heads (precautions/possible dangers?) if you need more input on my build, I will supply the info...
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Postby kwilliams » Thu Feb 07, 2008 6:04 am

I'd run the 200cc heads.
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Postby automotive breath » Thu Feb 07, 2008 7:47 am

For a relatively low RPM 350 cubic inch engine I like to go with the smaller
port volume to keep port velocity up. The Edelbrock performer RPM head
will support 500 HP with a flat top 350 with minimum porting.
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Postby jeffmckc » Thu Feb 07, 2008 8:19 am

If your staying with what you have for a while then the 170's if you add a gear and more converter later the 200,s
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Postby BH » Thu Feb 07, 2008 9:53 am

With the lower compression you'll be running a smaller port will work more efficeint giving you broader power. I suggest the dart 180 pro1 64cc chamber. This head has there latest wet flow technology. I have seen these and they are nice for the money.
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Postby ralph85 » Thu Feb 07, 2008 10:45 am

I built a 9:1 355 for my neighbor with maybe that exact cam (assuming it's a flat tappet hyd). I used a set of AFR 190s and a dual plane intake. There's plenty of low end torque and it's run a 12.2 in the 1/4 mile in a 3600+lb Nova with a 2800 stall converter and the wrong rear. With some tuning we might even get it into the 11s.

Unless you're using it in a tow truck, i wouldn't be afraid of using the 200cc intake.
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Postby chevyman18 » Thu Feb 07, 2008 12:32 pm

i am on a budget for the build. thats why i am sticking with either the darts for 1025, or the eddys for 999. my main concern is will i lose too much performance going with the 200cc? i have heard the flow will slow down because of the bigger intake, and i will lose hp and tq. so i just want to know before i buy any of the two heads. i'm also wondering about the aluminum eddys, is there anything bad about using aluminum heads? i am only 18, and this is my first build, i want to use parts that are gonna work, and last without problems (or least amount of).
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Postby BH » Thu Feb 07, 2008 1:00 pm

Here's the thing about this, if its going to be a low peak rpm like low 6000 rpm then a small port will hurt due to lower port speed. Yes a 200cc port will work as well but you'll have to rev it more to make it work especially with lower comppression like yours or add some compression. Also with your stock like botom end it won't last long if your reving high all the time. To keep it simple, low rpm works best with smaller ports the bigger the port the more cubes , rpm and compression needed. Seeing this is a stock daily driven street type engine then the smaller port will have more power sooner than a larger one. Hope this helps.
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Postby cfm » Thu Feb 07, 2008 1:30 pm

chevyman18 wrote:i am on a budget for the build. thats why i am sticking with either the darts for 1025, or the eddys for 999. i am only 18, and this is my first build, i want to use parts that are gonna work, and last without problems (or least amount of).


Very smart for a beginner ! IE: Asking questions and then coming to this forum.

$$$ and performance wise the Brodix IK180's should be on the list for consideration. They can be had for around $1050 just about everywhere.
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Postby chevyman18 » Thu Feb 07, 2008 1:43 pm

so in other words, stick with a 170cc or 180cc intake?
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Postby BH » Thu Feb 07, 2008 1:51 pm

Yes. The edelbroke air gap works really good on this as well FYI.
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Postby ralph85 » Thu Feb 07, 2008 1:59 pm

IMO, any of the heads in question will work well. If the application is mostly street driven, lean toward the smaller side. It will be more responsive. If it's going to be raced frequently, you'll probably want to upgrade your performance sooner than you think, so you might consider going a little larger to give you some growth. Some other things to consider:

You have an opportunity to increase your compression by adjusting the chamber size. You should consider it. Especially if you go with an aluminum head. You can go 10:1 or more on pump gas.

Make sure the intake will match up with the head port without doing a bunch of work.

If you have headers or plan to buy, make sure the plug angles are compatible (been there done that).

Good luck
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Postby chevyman18 » Thu Feb 07, 2008 2:05 pm

the engine is estimated at 9.6:1 with 64cc heads. i was thinking going with the fel-pro .015" thick gasket to bring it up to about 9.8-9.9:1 for the aluminum heads, if not i would use something thicker for the iron heads, and keep the compression around 9.6:1 to avoid any possibilities of detonation or overheating. i heard something about bolting aluminum heads down, that there is a possibility of the head bolts stretching and warping because of the expansion of the aluminum heads??
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Postby ralph85 » Thu Feb 07, 2008 3:18 pm

Your pistons are probably down .025, so that .015 head gasket should give you a quench height of .040 which will help mix things up and make it less detonation prone (you need to check tho). I've never used that gasket, but spoke to the Felpro engineer about it and it should be good for your combo. IF you can get alum heads for only marginally more than iron, the weight savings alone is probably worth it. That cam with a dual plane like an RPM air gap and a head with 180-200cc runners should work well in a street strip car. Very similar to my neighbor's combo.

Good luck
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Postby chevyman18 » Thu Feb 07, 2008 3:22 pm

ralph,
so in you opinion, you dont think there would be any performance difference in running the 170cc aluminums to the 200cc irons? or so little that it wouldnt make a difference?
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