GM 781 Cylinder Head Flow Bench Testing 620HP Street/Strip 454 Big Block Chevy
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- čas přidán 3. 04. 2018
- Part 12 - GM 781 Cylinder Head Flow Bench Testing
-In Depth Performance Engine Build
620+ Horse Power Street/Strip Pump Gas 454 Big Block Chevy - Auta a dopravní prostředky
Excellent video, this is the most clear demonstration of a flow bench I’ve seen. I’m enjoying this build series greatly, it’s great to see someone show exactly what all is involved in building an engine. 👍🏻
You showing the whole process of flowing the heads and showing all of the steps involved was great! I actually understand how it works now. Very good video. A person appreciates the time,effort and most of all knowledge that goes into building a HP engine after seeing your videos. You do great work Mark.
Thanks for the videos. Can't wait to see it in your Chevelle running.
Eric
Wow! This is fascinating. I've read about these procedures being performed on heads for years. Now I know why it can cost so much.
Correcting Mark shows lack of experience...esp the 320 Procomps are better. That there is funny. This dude is a master wth these heads nobody does iron anymore
you give r readings,but in no units. What are you measuring here ?
where is the flow bench after you put in the bigger valves?
Do they still use the SF600?
I thought by now they went digital!
Damn! You need a flowcom!
How much would it cost to have u build a set of 781s like this
Thats a pretty good head for a stock oval
How do you convert the results to cfm? You said these numbers are a percentage? Percentage of what?
Mark, what happened to vortec pro
where are you located in case I want to get head work?
So what is the cfm of the ports?
Interesting, do you feel the oval heads are superior to the rect. port ? I know the Rect. heads do have bigger valves, back in the day there was always so much debate of oval VS rect.
An oval shape is a much more efficient shape as far as airflow. (Air doesn't like
corners) Oval ports also have a smaller cross sectional area, which increases
air velocity. The square ports are just plain too big for most street driven big
blocks.
Look any of the modern prostock heads, they're all oval shaped.
The "bad" port exits into the cylinder wall, whereas the "good port" exits into the center
of the bore. That's what causes the flow discrepancy... fyi
He explains this in the video.
i have a set of 049 i stuck 2.300 intakes and it ended flowing 298 cfm at .550 lift, restriction is in the port now. 😂
Sorry , I didn't what the last part. So what would these heads flow if ported , thanks.
Interesting video! I would like to know how the flow bench meter works???
781 test here: stock head 2.06x1.72
Intake: cfm bad side (lowest cfm)
@200= 42.5
@300= 65.9
@400= 76
@500= 82.8
@600= 86.2
@700= 88.7
@750= 89
Exhauste: cfm
@200= 30
@300= 40
@400= 48.5
@500= 54.5
@600= 57.6
@700= 58
@750= 58
The cfm number times the amount of cylinders u have? So 89 times 8(cylinders)?
You need to put a pipe on the exhaust when testing. Your numbers will be arount 20 cfm low
Putting pipes on heads on flow benches give false readings!
@@Anarchy-Is-Liberty Wow, you really don't know what you're talking about. Maybe Hot Rod magazine will do an article on flow testing to get you up to speed.
Y did U block us seeing the 28" of water scale with your left hand on all of the different lift settings?
>>>>>?????
4 and 5 on intakes are always low #s
I think maybe you need to invest in a piece of string and find out where the airflow really goes.
In 2023 cost for valve job and shave heads true 500$ if valve guides needed 800$
Keep reading your hotrod mags! He is finding the flow rate of the ports. AFTER this procedure come the modifications he deems necessary!
Y even make a video ???
Y even watch?
Your work is excellent but at the end of your video your business information on contacting you flys by without enough time to copy it down why not have a still shot with your information because it goes by too fast causing us to repeat about 6 times to get it all. OK
There happens to be a pause button... FFS Jesus, low IQ people... psh
Even the Chinese after market heads are better than this don’t waste time on these heads I’ve done it and it’s not worth it
Anything American made is far better than any Chinese BS!! I will never put any Chinese junk on my classic American made automobiles!!!
Procomp heads😆