compression or flow?

[mopfried]

Thinking of a cheap build with avaiable parts that i already have.
360LA block with H116CP speed pro .030 over pistons, .005 in the hole.
Set of Edelbrock untouced (used, not ported) RPM 63 cc heads Quench closed chamber)
.036 head gasket... comes up as 10.6 static compressio.
4 speed in a dart. \
I know i need to be careful picking camshaft, but will 10.6 be too much compression for pump gas?
Hot street motor.. headers, 355 gear ..maybe fuel injection...

I have never ran aluminum heads.....
I have some W-2 iron heads (70 cc and no quench, Open chamber, ported .5 point dtop in compression)and all it take to run them except pushrods.

So the question is do i give up the poeted W2 flow for higher compression and quench?
what difference will either make?

 

[TT5.9mag]

I’ll take the ported W2s and less compression all day long and twice on Sunday.

 

[Plymouth 65]

Domed pistons in the 360 w/ported W2 heads. 65'

 

[Dan the man]

I'm probably wrong about this but I don't think that the extra flow will be much good with out compression. That's why I don't think that putting 360 heads on a stock 318 does much for performance, sure it helps flow but when the cr is under 8.0:1 the benefits of more flow has to suffer

 

[ch1ll]

Your dynamic compression ratio will be lower than your static 10.6 with your hot cam due to valve overlap. I belive believe wallace racing calculators has a dynamic compression ratio calculator that you figure in your cam specs.

I’d take compression over flow. Compression is key for hp especially at the higher rpm’s. The raw edelbrock heads won’t flow all that much less and are more forgiving at a higher ratio.

If I used the w2’s, I’d buy pistons to match.

 

[9secRR]

Dropping .5 in comp is nothing. Will not even notice it. There is no chance I would bolt on a set of edelbrock heads before W2’s.

 

[dusterbing the peace]

Do you have flow numbers for the W2s to know how much they out flow the Eddies? You’ll want to know what lift point you need to hit with the cam you’ve yet to pick (and get springs to match).

Rough maths:
estimated hp = 2.06*cfm
Then use Wallace calculator for weight and power, factoring in the extra 60 lbs for the W2s.

ET-MPH-HP Calculator

These are just ballparks to point you in a direction. As mentioned, that half point won’t affect much depending on actual flow achieved…not knocking the port work, but a grinder in the wrong hands can mess up the flow numbers pretty quick.

 

[OldmanRick]

With the 3.55', i'd probably run the Eddie's and build for upper/mid range torque. A cam in the [email protected] area along with big dual plane intake would work well in the 4k to 5700 rpm area and still be pump gas friendly plus allow a decent timing curve. Myself, i would just carb it.

 

[perfacar]

more air flow will produce more cylinder pressure , which makes more power, years ago. had a very sharp engine builder, stock n s/s said , he would give up .5 comp for more air flow or bigger cam. will go faster. just food for thought,

 

[Belvedere2]

I've never run Edelbrocks but I like W2s. Make sure they're both 70cc. Might weren't so cleaned up at 69. Close to 10:1, small Racer Brown Hydro in a 340. 180psi and runs on 93. Dynoed over 400 for what that's worth. Think your 360 would put out more if similiar build. Run at least those 3.55s and that Dart will fly.

 

[rumblefish360]

I'm probably wrong about this but I don't think that the extra flow will be much good with out compression. That's why I don't think that putting 360 heads on a stock 318 does much for performance, sure it helps flow but when the cr is under 8.0:1 the benefits of more flow has to suffer

Yes, you are incorrect.

Your dynamic compression ratio will be lower than your static 10.6 with your hot cam due to valve overlap.

Where in the mention of a cam in this thread?

Horse before the cart?

I belive believe wallace racing calculators has a dynamic compression ratio calculator that you figure in your cam specs.

Yep! In that sea of calculators….. it’s there!

Also @mopfried

I’d take compression over flow.

Bad move mostly if not every time. It’s been proven otherwise. Search member IQ52 for his results .

Compression is key for hp especially at the higher rpm’s. The raw edelbrock heads won’t flow all that much less and are more forgiving at a higher ratio.

The available octane and timing curve are more important to this than anything else.

If I used the w2’s, I’d buy pistons to match.

A zero deck .030 over flat top and a 70cc head and a .038 X 4.xxxx head gasket will deliver a very friendly local gas pump 91 octane while keeping the ability for a good timing curve.

The ratio will fall in around 9.7-1 - 10-1 depending on head gasket and head cc amount.

This I have done in the past, it’s not a problem.


Purchasing pistons to match a W2 head, to me, seems like your saying get domed pistons. I call this a bad move since the extra dome material is pushing the ratio, perhaps, maybe, over a 91 octane limit. 93 should still be in the ball park. It was for me.

Another possible draw back to a dome slug is how high the dome is and the work around them dependent on dome height and shape. The possibility of and IMO, for sure in my wheel house is to knock off the sharp edges and soften the slug to help prevent detonation.

Cylinder head flow (and with a capable intake!) makes more power than increasing the compression. While it’s really needed more and more for a large cam and the larger the cam is the more compression is needed to off set the overlap and loss of dynamic compression at low rpm.

Smallest cam I ran at 10-1 with iron heads was a MP circle track cam, 288/.497(?) - 108, also ran the Hyd 292/.508-110. I was in NY at the time and 93 octane was more than enough.

 

[273]

A point of cr is worth about 3-4 % in power so 1/2 a point gonna be 2% at best (10 ish hp).

I wouldn't worry about it.

 

[mopfried]

Do you have flow numbers for the W2s to know how much they out flow the Eddies? You’ll want to know what lift point you need to hit with the cam you’ve yet to pick (and get springs to match).

Rough maths:
estimated hp = 2.06*cfm
Then use Wallace calculator for weight and power, factoring in the extra 60 lbs for the W2s.

ET-MPH-HP Calculator

These are just ballparks to point you in a direction. As mentioned, that half point won’t affect much depending on actual flow achieved…not knocking the port work, but a grinder in the wrong hands can mess up the flow numbers pretty quick.

I bought the W2 heads used. The old Iron 810 castings. I was told they were ported by shady dell. I have no way of confirming that. I do have a set of W2 porting thempates and they fit perfectly.....

 

[mopfried]

Yes, you are incorrect.


Where in the mention of a cam in this thread?

Horse before the cart?


Yep! In that sea of calculators….. it’s there!

Also @mopfried

Bad move mostly if not every time. It’s been proven otherwise. Search member IQ52 for his results .





The available octane and timing curve are more important to this than anything else.




A zero deck .030 over flat top and a 70cc head and a .038 X 4.xxxx head gasket will deliver a very friendly local gas pump 91 octane while keeping the ability for a good timing curve.

The ratio will fall in around 9.7-1 - 10-1 depending on head gasket and head cc amount.

This I have done in the past, it’s not a problem.


Purchasing pistons to match a W2 head, to me, seems like your saying get domed pistons. I call this a bad move since the extra dome material is pushing the ratio, perhaps, maybe, over a 91 octane limit. 93 should still be in the ball park. It was for me.

Another possible draw back to a dome slug is how high the dome is and the work around them dependent on dome height and shape. The possibility of and IMO, for sure in my wheel house is to knock off the sharp edges and soften the slug to help prevent detonation.

Cylinder head flow (and with a capable intake!) makes more power than increasing the compression. While it’s really needed more and more for a large cam and the larger the cam is the more compression is needed to off set the overlap and loss of dynamic compression at low rpm.

Smallest cam I ran at 10-1 with iron heads was a MP circle track cam, 288/.497(?) - 108, also ran the Hyd 292/.508-110. I was in NY at the time and 93 octane was more than enough.

I have a strip dominator W2 intake. TTi W2 1-5/8x1-7/8 step headers. I have an old Crane SSH 320 cam that worked pretty well on an old 340 that closed @ 46 deg ABDC. 496" intake and 504" exhaust. I believe it was some where aroud 243 deg duration. I would probably look fr somethuing like that with maybe more lift.

 

[33IMP]

We have a vague idea of what flow to expect from rpm's. I'd have the W2's flowed, (if you have somebody local that can do it), to find out how much better they are. 5% better, I might run the rpms. 15%better, the W2's become a no-brainer.
With your w2 intake, headers and cam, I think I would use the W2's, 100%
In MY opinion, the half point loss in a pump.gas engine is a plus.

 

[rumblefish360]

I bought the W2 heads used. The old Iron 810 castings. I was told they were ported by shady dell. I have no way of confirming that. I do have a set of W2 porting thempates and they fit perfectly.....

MP template ported should equal 300cfm up top but as said above by 33 IMP, flow test them. The reason being (from where I sit) is the head may not flow as much as the aluminum head and if your not lifting the valve up very high, then your not taking advantage of the cylinder heads air flow capability.

With the lift you mentioned above on the camshaft, that’s not a lot and the W2 loves a high lifting valve and even better if it hangs open there for a bit. Search YouTube for https://m.youtube.com/results?sp=mAEA&search_query=charlie+servidio
And scroll down some and find him (and I) flow testing my W2 heads.
Here is a W5 flow test where you can see stock vs ported W5 heads which are basically a square port aluminum version of the W2. They had very similar flow curves.

I have a strip dominator W2 intake.

Excellent

TTi W2 1-5/8x1-7/8 step headers.

Excellent

I have an old Crane SSH 320 cam that worked pretty well on an old 340 that closed @ 46 deg ABDC. 496" intake and 504" exhaust. I believe it was some where aroud 243 deg duration. I would probably look fr somethuing like that with maybe more lift.

Lift wise, get as much as possible with the W series head. Check every cam grinder you can find. Howard’s, Schneider cams, Bullet are a few of the smaller companies that are also very very good to check out.

 

[junkyardhero]

i'll echo what several others have mentioned and say go with the W2's, especially if you have all the stuff to run them.

 

[PROSTOCKTOM]

It won't go without flow. That compression ratio loss won't have much if any power loss in that range, but lack of flow limits everything throughout the rpm range.

Tom

 

[RustyRatRod]

It won't go without flow. That compression ratio loss won't have much if any power loss in that range, but lack of flow limits everything throughout the rpm range.

Tom

What he said ^^^^^^^

 

[Newbomb Turk]

Dont worry about flow numbers. The W2 will out horsepower everything else even if it flows less.

Use the W2’s and forget all the rest.

 

[bigfoot]

MP template ported should equal 300cfm up top but as said above by 33 IMP, flow test them. The reason being (from where I sit) is the head may not flow as much as the aluminum head and if your not lifting the valve up very high, then your not taking advantage of the cylinder heads air flow capability.

With the lift you mentioned above on the camshaft, that’s not a lot and the W2 loves a high lifting valve and even better if it hangs open there for a bit. Search YouTube for https://m.youtube.com/results?sp=mAEA&search_query=charlie+servidio
And scroll down some and find him (and I) flow testing my W2 heads.
Here is a W5 flow test where you can see stock vs ported W5 heads which are basically a square port aluminum version of the W2. They had very similar flow curves.




Excellent


Excellent




Lift wise, get as much as possible with the W series head. Check every cam grinder you can find. Howard’s, Schneider cams, Bullet are a few of the smaller companies that are also very very good to check out.

The W2 and W5 share a few parts, but a W5 is nowhere close to a square port W5. I own both. Exhaust ports and exhaust bolt patterns are different, intake port floor is raised and ports are rectangle. Very different heads that share a few parts.

That being said if OP has a ported set of W2's and all the parts I would run them everyday before I bolted eddies on.

 

[PRH]

I guess I’ll be the outlier here……..

Mild stock stroke street motor with cast pistons, small-ish cam, 3.55 gears?

I’ll take the Ede heads.

 

[TT5.9mag]

I guess I’ll be the outlier here……..

Mild stock stroke street motor with cast pistons, small-ish cam, 3.55 gears?

I’ll take the Ede heads.

How come? I mean if the hard part of W2s is obtaining all of the rocker gear, valves, etc, and he has all of that, why wouldn’t you choose them over the Eddie’s?

 

[PRH]

I just feel like it’s a better match for the intended use(chugging along on the street with a manual trans with modest gearing), and I like aluminum heads with good quench for pump gas.

That’s how I’d do it, but to each their own.

 

[TT5.9mag]

I just feel like it’s a better match for the intended use(chugging along on the street with a manual trans with modest gearing), and I like aluminum heads with good quench for pump gas.

That’s how I’d do it, but to each their own.

I like different opinions, (and value yours quite a bit) thanks. I think in his other thread he mentioned wanting a “hot street” engine and the number 500hp was thrown around. Seems like a lofty goal for unported Eddie’s on a 9.8-10:1 360 IMHO.