Simple SBF Highport porting question, please

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fasteach
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Simple SBF Highport porting question, please

Post by fasteach » Mon Jul 09, 2018 6:43 pm

Hello;
I bought a set of 192cc "fast-as-cast" heads, and thanks to some kind advice i got on YB i'm in the process of opening them up to 2.05 Sq.in at the pushrod pinch (MCSA).

Here's the thing; I widened the ports by laying back the pushrod bulge .050, and it gained flow as well as letting the pinch velocity go apeshit (340+fps).
I raised the roof to a 1262 gasket all the way back to the guide boss, and now have 1.98 Sq.in. and the port gained from .400 on up, and the port velocity stayed the same.

I would like to continue gaining area at the pinch, but when i (gently) tinkered with the pushrod bulge, my test port flow separated right after the bulge and lost 7cfm from .500 on up.
With the intake manifold bolted on, the port doesnt seem to exhibit the turbulence and flows the same as the other ports.

I was wondering if its safe to gain area on the right side wall in an effort to reach my runner volume, as well as slow down the pinch velocity, without risk of throwing the rest of the ports into separation?
Right now the other ports are 1.950Tx1.150W with 3/8 corners at the pinch, and flow the same 308cfm at max lift as when tested with a valve installed upside down.

as delivered on my bench:... .100=68, .200=133, .300=199, .400=248, .500=274, .600=284, .700=290, .800=291.
raising roof and p-rod blend...100=68, .200=129, .300=199, .400=253, .500=280, .600=297, .700=304, .800=308.

I'm not really looking for more flow, but the center of port velocity seems fast (340fps) and the SSR is 360fps.
This will be a 333 (4.040x3.250 11:1 274/288 .728/.707 108-108 solid roller for nitrous) so i believe i could use some more area to calm things down.
Any advice you could offer would do me a world of good and would be greatly appreciated.

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Re: Simple SBF Highport porting question, please

Post by KnightEngines » Mon Jul 09, 2018 7:37 pm

Fast is good provided it's stable & can support the motor.
340ft/s through the pinch & 360 over the turn is not that fast - remember it's flowing pretty much 300cfm @ .600" lift, unless you're turning it to the moon a little 330 cuber is not going to use that flow, slowing it down will just hurt inerita ram & kill cylinder fill ABDC.

300cfm @ 2" MCSA is nice, that'll support the motor to 7000rpm or a bit more, at which it'll only be demanding around 250cfm.
If you want more rpm then open up the MCSA & make sure it's stable, but don't go chasing flow, you have plenty.

If 7000 peak & 7500rpm over-rev is good for you then leave it, you're good to go.

Remember - if you mess with a thing for long enough, eventually you will screw it up.

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Re: Simple SBF Highport porting question, please

Post by philly » Mon Jul 09, 2018 10:52 pm

KnightEngines wrote:
Mon Jul 09, 2018 7:37 pm


Remember - if you mess with a thing for long enough, eventually you will screw it up.
story of my life :oops:
phil.

fasteach
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Re: Simple SBF Highport porting question, please

Post by fasteach » Wed Jul 11, 2018 12:05 pm

Thank you for your advice...i appreciate it.
The original plan was to open the MCSA up to 2.05 for 7500 rpm, but since the left side of the test port is so sensitive, and i've already raised the roof .100, i wondered if widening the right side wall was a less risky route to take while looking for my 2.05/215cc objective.
Thank you for easing my mind about the port velocity. Much of my reading here over the years led me into thinking my numbers were too fast.

Your observations are appreciated and your observation makes perfect sense...it makes enough flow to just try them as-is, and see what happens.
Just an anecdotal mention, but the ports flow 282cfm with the funnelweb manifold attached, so i'm well past the 250cfm you mentioned.
Thanks again!

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Re: Simple SBF Highport porting question, please

Post by mag2555 » Wed Jul 11, 2018 12:20 pm

Stop right where you are as you are already loosing some very important flow at .200" !
Have you CCed the head now to see if your percent of flow gain matches or exceed's your gain in port volume?

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Re: Simple SBF Highport porting question, please

Post by fasteach » Wed Jul 11, 2018 12:47 pm

Thank you for the good catch!
I could've sworn i included the 204cc statement in my original post, my apologies.
In my defense, the 2 flows i've included are not from the same "before and after"port, so there may be some variance in the valve seat configuration as delivered from TFS.

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Re: Simple SBF Highport porting question, please

Post by swampbuggy » Wed Jul 11, 2018 12:51 pm

Fasteach...How much power are you hoping for ( or did i miss it ) ? Mark H.

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Re: Simple SBF Highport porting question, please

Post by fasteach » Wed Jul 11, 2018 1:37 pm

Swamp, thanks for looking.
I'm hoping the engine will make 525ish on muscle, but Dean Harvey @ compcams specced the cam for a 300hp shot.

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Re: Simple SBF Highport porting question, please

Post by swampbuggy » Wed Jul 11, 2018 2:43 pm

It is a pretty well accepted rule of thumb that an engine (should) produce 2 H.P. per each CFM of flow. Example 300 CFM X 2=600 H.P. . BUT all the other parts HAVE to be optimal to compliment the head flow. Carb., intake, camshaft, exhaust are the more important ones, but there are other items as well. This being said, you should have plenty of flow to easily reach your goal IMO. Mark H. :)

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Re: Simple SBF Highport porting question, please

Post by blykins » Wed Jul 11, 2018 2:53 pm

philly wrote:
Mon Jul 09, 2018 10:52 pm
KnightEngines wrote:
Mon Jul 09, 2018 7:37 pm


Remember - if you mess with a thing for long enough, eventually you will screw it up.
story of my life :oops:
You too huh?
Lykins Motorsports
brent@lykinsmotorsports.com
www.lykinsmotorsports.com

fasteach
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Re: Simple SBF Highport porting question, please

Post by fasteach » Wed Jul 11, 2018 6:18 pm

Swamp;
After playing with Cleveland heads for 30 years, i've learned that the world doesnt revolve around a flowchart,
and "rules-of-thumb" work...till they dont.

Sq.in of area must be appropriate for the displacement, and if the port is right, it will move air.
I tried and tried to trick my BOSS302s into needing 3sq/in, epoxy, 2.19 valves and 365cfm...they werent impressed with my efforts.

Dont get me started on cam companys with 20-somethings recommending valve events for heads that were obsolete before they were even born.

Now at 50 years old, my back is just too tired to lift 54lb heads on and off, around shock towers and export braces.

This new-fangled aluminum inline head is like nothing i've experienced and so im trying not to ruin a good thing from tinkering...
It's as if Knights engines already knows me :lol:

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Re: Simple SBF Highport porting question, please

Post by Rick360 » Wed Jul 11, 2018 7:16 pm

mag2555 wrote:
Wed Jul 11, 2018 12:20 pm
Stop right where you are as you are already loosing some very important flow at .200" !
Have you CCed the head now to see if your percent of flow gain matches or exceed's your gain in port volume?
Ignore ^^this^^ completely WRONG comment. Low lift flow only matters on the flowbench.

Focus on having a consistent csa thru the length of the port. There is no good flowing port that isn't fast around a turn. I've seen really good ports (horsepower) well over 400fps on the SSR on the bench. Make the SSR a nice radius starting just above the seat.

Rick

fasteach
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Re: Simple SBF Highport porting question, please

Post by fasteach » Sat Jul 14, 2018 5:30 pm

Thank you Gentlemen, for taking the time to offer some valuable advice from your experience.
Much appreciated.
Duke

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Re: Simple SBF Highport porting question, please

Post by MELWAY » Sat Jul 14, 2018 8:56 pm

Sounds like a cool project

What size intake valve and seat angles are you working with?

That cam sounds awful big for 11.1 comp on that size engine. If will LOVE the dope button
3370lb Sedan 9.89@136MPH 358chevN/A

fasteach
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Re: Simple SBF Highport porting question, please

Post by fasteach » Sat Jul 14, 2018 9:36 pm

Melway, the heads come with 2.02int/1.60ex, with seats already cut. intake seats are 35/45/60 from TFS.
The combo is a duplicate of a buddy's, that runs 5.70/122 1/8 mile in a fox...different cam for my weight, and my porting instead of his.

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