yellow rose
Overnight Sensation
That makes perfect sense...you are raising the floor, speeding up the air. That’s pretty much what I think happens when the intake gets bolted on.
Cylinder Head Porting and Power Production
- Thread starter RAMM
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That makes perfect sense...you are raising the floor, speeding up the air. That’s pretty much what I think happens when the intake gets bolted on.
MOPAROFFICIAL
Oogliboogli
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MOPAROFFICIAL
Oogliboogli
Thread crashed
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sorry for the delay gentlemen. My hands started to tremble and shake. I realized I was really hungry.
I’ll be Measuring from where the cylinder heads deck meets the blocks deck to the lowest point of the bottom the intake port as requested.
Here are my 4 hooligans!
CNC’d ProMaxx (SM) representing stock (-ish?) .205
As cast, last gen, W2/769 .610
As cast W5, .680
BM ported, same
The port itself isn’t raised from the deck but more in the length of the runner IIRC. I don’t have a short block readily handy to lay them on to measure from the deck to the underside of the port, but the pairing picture of the 2 W heads deck to deck is interesting.
First, the decks didn’t meet flat, in order to get the heads deck to deck, it leaves a gap. Then you can see the difference. The W5 is .504 taller laying them deck to deck.
I’ll be Measuring from where the cylinder heads deck meets the blocks deck to the lowest point of the bottom the intake port as requested.
Here are my 4 hooligans!
CNC’d ProMaxx (SM) representing stock (-ish?) .205
As cast, last gen, W2/769 .610
As cast W5, .680
BM ported, same
The port itself isn’t raised from the deck but more in the length of the runner IIRC. I don’t have a short block readily handy to lay them on to measure from the deck to the underside of the port, but the pairing picture of the 2 W heads deck to deck is interesting.
First, the decks didn’t meet flat, in order to get the heads deck to deck, it leaves a gap. Then you can see the difference. The W5 is .504 taller laying them deck to deck.
So I looked into the engines book to see what it said about raised. I thought I read .500, but that seemed like a lot. So, still being a bit Inquisitive I measured the ports depth from the intake face to the backside side of the guide.
W2 = 3.06
W5 = 3.16
Hum...
How about intake manifold attaching points?
Bottom of threaded hole to the deck.
W2 = 1.26
W5 = 1.46
W2 = 3.06
W5 = 3.16
Hum...
How about intake manifold attaching points?
Bottom of threaded hole to the deck.
W2 = 1.26
W5 = 1.46
Hummmm
Intake surface to the cylinder head attaching bolt hole measurements...
View attachment 1715677264
Ahhh, here is something, .300 longer for the W5.
W2 @ 2.33
W5 @ 2.63
Intake surface to the cylinder head attaching bolt hole measurements...
Ahhh, here is something, .300 longer for the W5.
W2 @ 2.33
W5 @ 2.63
PRH
Well-Known Member
My buddies 350 Pontiac Stocker has gone 10’s @3300lbs with heads that flow 200 @.420 lift(max lift).
With the stock intake and carb....... it’s over 2.06hp/ci.
I guess those Pontiac engineers knew what they were doing......30* seats and all.
I never really look at hp/cfm, but it appears both his 350 and 400 stocker motors make the same hp/cfm.
The 350 is slightly better in the hp/ci dept though.
With the stock intake and carb....... it’s over 2.06hp/ci.
I guess those Pontiac engineers knew what they were doing......30* seats and all.
I never really look at hp/cfm, but it appears both his 350 and 400 stocker motors make the same hp/cfm.
The 350 is slightly better in the hp/ci dept though.
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My buddies 350 Pontiac Stocker has gone 10’s @3300lbs with heads that flow 200 @.420 lift(max lift).
With the stock intake and carb....... it’s over 2.06hp/ci.
I guess those Pontiac engineers knew what they were doing......30* seats and all.
I never really look at hp/cfm, but it appears both his 350 and 400 stocker motors make the same hp/cfm.
The 350 is slightly better in the hp/ci dept though.
And let me guess with a QJet.
PRH
Well-Known Member
Of course.
I don’t recall testing any of his heads with the intake installed, but based on other heads Ive tested with the factory intake installed........ there should be a pretty noticeable negative impact on the flow with it attached to the head.
I don’t recall testing any of his heads with the intake installed, but based on other heads Ive tested with the factory intake installed........ there should be a pretty noticeable negative impact on the flow with it attached to the head.
PRH
Well-Known Member
I freshened a set of 906’s used on a 440-4 NHRA SS build.
It’s a 1970, and I believe it runs the big AVS carb(stock 440 carb).
Flat tops, big roller, stock valve sizes, heads ported but under 203cc intake volume.
It went 9.70’s@3250-ish....... shows 650hp on the Moroso Chart(not dynoed).
The point being........ some people have figured out how to make pretty good power and run pretty fast with heads that “aren’t as good as” some of the stuff available off the shelf.
If you took the newer better heads, and applied the same energy and effort into the combos using them as what was done with the stock heads......you’d make even more power and go even faster.
It’s a 1970, and I believe it runs the big AVS carb(stock 440 carb).
Flat tops, big roller, stock valve sizes, heads ported but under 203cc intake volume.
It went 9.70’s@3250-ish....... shows 650hp on the Moroso Chart(not dynoed).
The point being........ some people have figured out how to make pretty good power and run pretty fast with heads that “aren’t as good as” some of the stuff available off the shelf.
If you took the newer better heads, and applied the same energy and effort into the combos using them as what was done with the stock heads......you’d make even more power and go even faster.
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So Hysteric, now that I showed you my 352/stock head hardware, what do you think?
PRH
Well-Known Member
I can’t think of a single engine I built where I felt there was “no more” power left on the table for one reason or another.
There is usually a budget, and then a fairly well defined combo is determined, along with the projected power output.
I can only think of a couple of instances where the power came in under expectations(close but no cigar).
And in those cases, I wouldn’t have changed anything with regards to the heads to “fix” those combos.
My feeling is that most combos fall short of completely “using up” the heads.
So, if something like a cam swap nets a 30hp improvement, the hp/cfm goes up....... but not because you improved the heads.
For me, looking at hp/cfm is similar to looking at bsfc.
It’s a “result”, and not really something I’m thinking about while formulating “the plan”.
There is usually a budget, and then a fairly well defined combo is determined, along with the projected power output.
I can only think of a couple of instances where the power came in under expectations(close but no cigar).
And in those cases, I wouldn’t have changed anything with regards to the heads to “fix” those combos.
My feeling is that most combos fall short of completely “using up” the heads.
So, if something like a cam swap nets a 30hp improvement, the hp/cfm goes up....... but not because you improved the heads.
For me, looking at hp/cfm is similar to looking at bsfc.
It’s a “result”, and not really something I’m thinking about while formulating “the plan”.
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PRH
Well-Known Member
Yes.
Considering you were trying to Ram down my throat and sell everyone a lie in the falsehood of what you were saying, a total lie. Just throwing mud to see if it would stick. IDK, what am I trying to say.
What should you be saying?
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And what false hood was that?
Oh come on now!!!!!
@RAMM this is a great thread. Thanks for taking the time. A lot of good info.
I'll tell you what I'd like to see also, though. A cost comparison per HP gained. I'm always concerned about budget and I'm sure a lot of others are too. Seeing these "all out" efforts is great, but the average person can't afford that. Just wondering, for example, if you can give a cost comparison for instance from say a "street" port to a "street/strip" port to an "all out" port? I realize costs vary due to location, but I'm curious as to HP gained versus cost. IF that makes sense. Or maybe better put, CFM gained versus cost, if that puts it better.
I'll tell you what I'd like to see also, though. A cost comparison per HP gained. I'm always concerned about budget and I'm sure a lot of others are too. Seeing these "all out" efforts is great, but the average person can't afford that. Just wondering, for example, if you can give a cost comparison for instance from say a "street" port to a "street/strip" port to an "all out" port? I realize costs vary due to location, but I'm curious as to HP gained versus cost. IF that makes sense. Or maybe better put, CFM gained versus cost, if that puts it better.
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Oh come on now!!!!!
No. Really.
rmchrgr
Skate And Destroy
Just wanted to update on the exhaust port question I asked early on. I apologize if this is ridiculously obvious to some here but looking at it this way helped me to see things more clearly.
Anyway, the presumptive reason the intake gets focused on when porting (and generally why the intake valve is larger than the exhaust) is because of pressure differential.
It is much harder to fill the cylinder with the intake charge because you are relying on atmospheric pressure to do it. That pressure is reduced further (vacuum) in the intake tract when the piston is pulling down so it makes sense that any extra volume of the A/F mixture combined with a less obstructed pathway into the cylinder would clearly help to overcome the lack of pressure.
But once combustion occurs and the mixture is pushed out, the pressure of the mixture becomes much greater so the extra volume is not needed. Making the pathway less obstructed is obviously beneficial in both instances but again, the exhaust port volume is not as important. I'll be honest, I never thought about it like that.
Carry on.
Anyway, the presumptive reason the intake gets focused on when porting (and generally why the intake valve is larger than the exhaust) is because of pressure differential.
It is much harder to fill the cylinder with the intake charge because you are relying on atmospheric pressure to do it. That pressure is reduced further (vacuum) in the intake tract when the piston is pulling down so it makes sense that any extra volume of the A/F mixture combined with a less obstructed pathway into the cylinder would clearly help to overcome the lack of pressure.
But once combustion occurs and the mixture is pushed out, the pressure of the mixture becomes much greater so the extra volume is not needed. Making the pathway less obstructed is obviously beneficial in both instances but again, the exhaust port volume is not as important. I'll be honest, I never thought about it like that.
Carry on.
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