383 sbc first dyno experience
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Re: 383 sbc first dyno experience
Good stuff Steve and Thanks for sharing. Very nice work! Still trying to wrap my head around the valve sizing though LOL. I just come here to learn.... as a hobbyist. I think most people looking for the most power out of that combo at that rpm range would be using a head with a 2.05 or 2.08 valve. Your MCSA is supporting the power you're making. A bigger valve should flow more air if the bowl/throat/chamber supported the larger valve....but does something just work better with the smaller valve? It must be flowing a full curtain of air well past the the lift point of 25%/VALVE DIA. Having the bowl shape concentric with the valve stem must help? I know some porters are blowing the bowls out to 105% of valve diameter chasing super high lift flow numbers and making good power. Just boggles my mind Haha
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Re: 383 sbc first dyno experience
For that combo there probably is some luck as well as I don't fully understand what is going on.Bob Hollinshead wrote: ↑Wed Aug 03, 2022 11:57 pm Good stuff Steve and Thanks for sharing. Very nice work! Still trying to wrap my head around the valve sizing though LOL. I just come here to learn.... as a hobbyist. I think most people looking for the most power out of that combo at that rpm range would be using a head with a 2.05 or 2.08 valve. Your MCSA is supporting the power you're making. A bigger valve should flow more air if the bowl/throat/chamber supported the larger valve....but does something just work better with the smaller valve? It must be flowing a full curtain of air well past the the lift point of 25%/VALVE DIA. Having the bowl shape concentric with the valve stem must help? I know some porters are blowing the bowls out to 105% of valve diameter chasing super high lift flow numbers and making good power. Just boggles my mind Haha
3 things that are probably not correct in Google land-
Mis-matched spacer
Mis- matched 300-25 intake manifold, I did that intake to fit my Dart 180 SHP heads.
The combustion chamber not going to the bore wall.
I have more questions than answers unfortunately.
I agree with you on the bigger valve if bowl etc is sized for application. But how big will the front halve of intake port be.
I know it nearly impossible on a 23 deg head but I think we should work towards as constant a CSA through the port but hard to achieve.
My pinch is 2.05"
Throat is 2.27"
Avg csa is around 2.10"
Bob,
Do you have any opinions on how you would improve the cylinder heads without increasing valve sizes, remember I am nearly at max at the pinch
steve c
"Pretty don't make power"
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Re: 383 sbc first dyno experience
When I done my calculations before dyno I was sure it would peak at 6300rpm.
The dyno guys say it is the intake helping the head carry ?
I would like to hear anyone who has has good experience with a undersized valve/bore and made more power than expected.
If you look at the port mould the SSR is not layed way back,I tried to shape it instead of laying way down to get the big number, maybe the shape works well for turning the fuel?
I really wish dyno shop had there fuel flow meters working correctly, would be interesting.
The dyno guys say it is the intake helping the head carry ?
I would like to hear anyone who has has good experience with a undersized valve/bore and made more power than expected.
If you look at the port mould the SSR is not layed way back,I tried to shape it instead of laying way down to get the big number, maybe the shape works well for turning the fuel?
I really wish dyno shop had there fuel flow meters working correctly, would be interesting.
steve c
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Re: 383 sbc first dyno experience
I ordered another set of 255/60/15 R series this week.skinny z wrote: ↑Sat Jul 30, 2022 12:39 pmAre you liking the new tires?steve cowan wrote: ↑Sat Jul 30, 2022 5:48 am New 255/60/15 R series radials.
Still turning tyres off the hit as shown in the 60ft
I'm assuming those are the Mickey Thompson ET Street R Radial Tires 3553.
I'm in the market for 255/50/16's myself but M/T only offers the SS version in a 16".
Been told up to 12 months wait
steve c
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Re: 383 sbc first dyno experience
12 months!steve cowan wrote: ↑Thu Aug 04, 2022 5:13 amI ordered another set of 255/60/15 R series this week.skinny z wrote: ↑Sat Jul 30, 2022 12:39 pmAre you liking the new tires?steve cowan wrote: ↑Sat Jul 30, 2022 5:48 am New 255/60/15 R series radials.
Still turning tyres off the hit as shown in the 60ft
I'm assuming those are the Mickey Thompson ET Street R Radial Tires 3553.
I'm in the market for 255/50/16's myself but M/T only offers the SS version in a 16".
Been told up to 12 months wait
Man, I thought two months for pistons was bad.
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Re: 383 sbc first dyno experience
Steve did you do any flow tests without a valve? What back cut on the valve?
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Re: 383 sbc first dyno experience
Build back betterskinny z wrote: ↑Thu Aug 04, 2022 11:01 am12 months!steve cowan wrote: ↑Thu Aug 04, 2022 5:13 amI ordered another set of 255/60/15 R series this week.
Been told up to 12 months wait
Man, I thought two months for pistons was bad.
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Re: 383 sbc first dyno experience
When I first started with my bench I flowed without valve but was soon told to stop doing itBob Hollinshead wrote: ↑Fri Aug 05, 2022 12:18 am Steve did you do any flow tests without a valve? What back cut on the valve?
The valve is the restriction so let's work around that.
Do you have a bench or access to a bench?
steve c
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Re: 383 sbc first dyno experience
Sorry,forgot about backcuts.
No backcuts on valves, I have done some bench testing but that's all.
I still find the subject confusing and it's probably the most argued subject.
No backcuts on valves, I have done some bench testing but that's all.
I still find the subject confusing and it's probably the most argued subject.
steve c
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Re: 383 sbc first dyno experience
Thanks for sharing info, I don't have a bench but have wanted to build one.
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Re: 383 sbc first dyno experience
What method do you use to measure cross sectional areas - specifically port dimensions.steve cowan wrote: ↑Thu Aug 04, 2022 1:43 amFor that combo there probably is some luck as well as I don't fully understand what is going on.Bob Hollinshead wrote: ↑Wed Aug 03, 2022 11:57 pm Good stuff Steve and Thanks for sharing. Very nice work! Still trying to wrap my head around the valve sizing though LOL. I just come here to learn.... as a hobbyist. I think most people looking for the most power out of that combo at that rpm range would be using a head with a 2.05 or 2.08 valve. Your MCSA is supporting the power you're making. A bigger valve should flow more air if the bowl/throat/chamber supported the larger valve....but does something just work better with the smaller valve? It must be flowing a full curtain of air well past the the lift point of 25%/VALVE DIA. Having the bowl shape concentric with the valve stem must help? I know some porters are blowing the bowls out to 105% of valve diameter chasing super high lift flow numbers and making good power. Just boggles my mind Haha
3 things that are probably not correct in Google land-
Mis-matched spacer
Mis- matched 300-25 intake manifold, I did that intake to fit my Dart 180 SHP heads.
The combustion chamber not going to the bore wall.
I have more questions than answers unfortunately.
I agree with you on the bigger valve if bowl etc is sized for application. But how big will the front halve of intake port be.
I know it nearly impossible on a 23 deg head but I think we should work towards as constant a CSA through the port but hard to achieve.
My pinch is 2.05"
Throat is 2.27"
Avg csa is around 2.10"
Bob,
Do you have any opinions on how you would improve the cylinder heads without increasing valve sizes, remember I am nearly at max at the pinch
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Re: 383 sbc first dyno experience
Once I am getting close to where I think it should be I usually do a port mould then cut it in sections and put on graph paper.Arthur wrote: ↑Sat Aug 06, 2022 11:54 pmWhat method do you use to measure cross sectional areas - specifically port dimensions.steve cowan wrote: ↑Thu Aug 04, 2022 1:43 amFor that combo there probably is some luck as well as I don't fully understand what is going on.Bob Hollinshead wrote: ↑Wed Aug 03, 2022 11:57 pm Good stuff Steve and Thanks for sharing. Very nice work! Still trying to wrap my head around the valve sizing though LOL. I just come here to learn.... as a hobbyist. I think most people looking for the most power out of that combo at that rpm range would be using a head with a 2.05 or 2.08 valve. Your MCSA is supporting the power you're making. A bigger valve should flow more air if the bowl/throat/chamber supported the larger valve....but does something just work better with the smaller valve? It must be flowing a full curtain of air well past the the lift point of 25%/VALVE DIA. Having the bowl shape concentric with the valve stem must help? I know some porters are blowing the bowls out to 105% of valve diameter chasing super high lift flow numbers and making good power. Just boggles my mind Haha
3 things that are probably not correct in Google land-
Mis-matched spacer
Mis- matched 300-25 intake manifold, I did that intake to fit my Dart 180 SHP heads.
The combustion chamber not going to the bore wall.
I have more questions than answers unfortunately.
I agree with you on the bigger valve if bowl etc is sized for application. But how big will the front halve of intake port be.
I know it nearly impossible on a 23 deg head but I think we should work towards as constant a CSA through the port but hard to achieve.
My pinch is 2.05"
Throat is 2.27"
Avg csa is around 2.10"
Bob,
Do you have any opinions on how you would improve the cylinder heads without increasing valve sizes, remember I am nearly at max at the pinch
steve c
"Pretty don't make power"
"Pretty don't make power"
Re: 383 sbc first dyno experience
Short of pouring a mold, can a guy get in there with a pair of inside dividers and get a measurement that way?steve cowan wrote: ↑Sun Aug 07, 2022 12:18 am Once I am getting close to where I think it should be I usually do a port mould then cut it in sections and put on graph paper.
Kevin
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Re: 383 sbc first dyno experience
Yes,inside divider or telescope snap gauges but I think where people get lost is calculations on corner radius. Larry has mentioned he has made templates that he uses.skinny z wrote: ↑Tue Aug 09, 2022 11:49 amShort of pouring a mold, can a guy get in there with a pair of inside dividers and get a measurement that way?steve cowan wrote: ↑Sun Aug 07, 2022 12:18 am Once I am getting close to where I think it should be I usually do a port mould then cut it in sections and put on graph paper.
Experienced guys use divider and alot is the shape .
Even on a 23 degree head you should be able to see a fair amount of the valve.
Measuring inside ports and intake manifolds is difficult and time consuming.
steve c
"Pretty don't make power"
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Re: 383 sbc first dyno experience
Yeah. I had considered the corners being problematic.steve cowan wrote: ↑Tue Aug 09, 2022 3:13 pmYes,inside divider or telescope snap gauges but I think where people get lost is calculations on corner radius. Larry has mentioned he has made templates that he uses.skinny z wrote: ↑Tue Aug 09, 2022 11:49 amShort of pouring a mold, can a guy get in there with a pair of inside dividers and get a measurement that way?steve cowan wrote: ↑Sun Aug 07, 2022 12:18 am Once I am getting close to where I think it should be I usually do a port mould then cut it in sections and put on graph paper.
Experienced guys use divider and alot is the shape .
Even on a 23 degree head you should be able to see a fair amount of the valve.
Measuring inside ports and intake manifolds is difficult and time consuming.
That said, working in a manufacturing machine shop has it's tool advantages. Maybe QA has the right gizmo for the job. We measure everything.
Once I get into it, I'd like to have covered all the bases covered regarding these heads as I'll be posing a couple of questions about their potential.
Thanks Steve.
Kevin