SBM Edelbrock/Speedmaster Head Data

[PRH]

When dealing with stock or entry level type heads, many times the rest of the port isn’t up to the task.
On that type of head, especially in milder applications, the pinch is not the limiting factor for power production.

 

[273]

When dealing with stock or entry level type heads, many times the rest of the port isn’t up to the task.
On that type of head, especially in milder applications, the pinch is not the limiting factor for power production.

I could see that, the other day was moving stuff around and came across my old J heads and couldn't believe how small the ports are

 

[polyjohn]

Wow Guys, just brilliant and very technical all at once!

The long and short of it is:-

If you haven't got a decent bench, then don't think about all out porting DOH!

There is an old adage, ''if it looks right, then it probably is right''.

Can a SM 170 head be ported to 300cfm without a degree in science?

Great work porting guys, you take my breath away with these flow numbers.

On a slightly different note, are the CNC ported SM heads any good, what do they flow???

 

[Earlie A]

Wow Guys, just brilliant and very technical all at once!

The long and short of it is:-

If you haven't got a decent bench, then don't think about all out porting DOH!

There is an old adage, ''if it looks right, then it probably is right''.

Can a SM 170 head be ported to 300cfm without a degree in science?

Great work porting guys, you take my breath away with these flow numbers.

On a slightly different note, are the CNC ported SM heads any good, what do they flow???

Here's how the stock SM, the CNC SM and the stock Trick Flows tested on my bench. All 2.02 valves.

Porting the SM to 270-280 is not that difficult, especially if using a 2.055 or 2.08 valve. Getting to 300 takes some work and some testing/cutting machinery.

 

[cookietruck]

That TF port really starts working at .250”

 

[Earlie A]

That TF port really starts working at .250”

Yes, compared to the other two it keeps working for longer.

 

[273]

One of the guy's at TF said for their street heads they really focus on flows between .300-.500" lift.

 

[PRH]

Imo, the curve on the cnc SM is as unimpressive as it is because it’s poorly executed.

With a more refined throat and valve job, the numbers in the middle could be noticeably better.

They’re in it for the quick cash and banking on the CNC buzzword for sales.

It’s pretty bad when there are areas near the middle of the curve where the ootb untouched head is better.

 

[273]

Imo, the curve on the cnc SM is as unimpressive as it is because it’s poorly executed.

With a more refined throat and valve job, the numbers in the middle could be noticeably better.

They’re in it for the quick cash and banking on the CNC buzzword for sales.

It’s pretty bad when there are areas near the middle of the curve where the ootb untouched head is better.

And the sad part is how hard would of it been to find someone to do a decent port job they could of copied, even now how hard would it be to update their cnc program to a better port shape.

 

[Earlie A]

Imo, the curve on the cnc SM is as unimpressive as it is because it’s poorly executed.

With a more refined throat and valve job, the numbers in the middle could be noticeably better.

They’re in it for the quick cash and banking on the CNC buzzword for sales.

It’s pretty bad when there are areas near the middle of the curve where the ootb untouched head is better.

I could not agree more. Large bowl and a 93% throat on my CNC SM head. I hope other heads are better than mine.

 

[PRH]

The problem isn’t really in the bulk of the cnc “porting”…….., it’s detail work in the seat and bowl area, and how well that transition is sorted out.

And the fact is, it takes expensive machines, with operators given ample time to get that transition done right.
When you’re building a product around a low price point, that just doesn’t fit into the equation.
So, what you get instead is a blown out bowl that can be made to mate up with a way less than optimal ootb valve seat shape.
Once the valve has been opened up enough to get clear of the influence from the seat, the cnc work done upstream finally starts to reveal itself.
Which, in EA’s example is after .450” lift.

Without getting into too much detail and derailng this thread, an example of what I’m talking about are these results from a CNC ported BBM head.
Without doing any work other than in the immediate seat/bowl area(no additional porting in the runners), by implementing a more air flow friendly seat profile, adding a small back cut to the valve, and blending away a little ridge around the OD of the valve job I was able to pick up:
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With basically zero gain in runner volume.