Відео

Will a modified 800cfm Quadrajet per you book making 1020 cfm support a 600 hp Small block Chevy?

I left three responses to the survey. In addition. I would love to prove Eric's truck can be made faster with a smaller cam, and better driveline components. His HP is extremely high for the times he is turning. It is easily a 9 second truck if he utilized more torque than rpm.

Thanks DV. Everyone learns from each other. I'm glad Eric called you.

Yep. The track can be a great dyno

would like to know more about Mission Impossible if you have the time. I'm a SBF guy and anything to do with Windsor SBF is awesome!

There is no dought that head desingners have used your knowledge to then call there head the Best!

Interesting vid thanks dave

I’ve been watching your videos for about 5 months now and I’m 16

Hate that I missed this live! Lake Speed is a great guy and this session really touched on a lot of subjects and some really interesting details that are often glossed over or never even brought up.

I always try for the best velocity for the usable RPM of the engine combination, which should match its use. Everything has to work together. Even connecting rod length affects airflow requirements. The most common mistake I see in amateur, or even some "gurus", is a completely mismatched combination, such as a 350 Olds engine with stock heads and compression, a hot street cam, with a big single-plane, massive carb, 2" headers, a 5,000 stall convertor and 4:56 gears. I had told the owner what would happen; but he went ahead and as predicted, it came out of the hole like a jack the bear and fell flat on its face because it couldn't rev to use all the high-RPM parts. Another good one was a plow truck 350 Chev engine, which needs low RPM torque. A local shop recommended 882, 76cc head with 2.02 and 1.6 valves, angle milled for more compression, flat-top hypereutectics, an old L79, 350HP, 327 hydraulic cam, a single plane with an 850 double pumper but running exhaust stock manifolds. They also told him the intake side didn't have to be milled after angle-milling the face. Other than the compression increase, everything else was high-RPM, not low RPM torque.

Thank you DV. I'm a poor boy racer. What's up know about you long time ago. I got a bunch of books you put me in victory circle.

Brilliant - thanks for that explanation.

A BMC B series engine video would be hot hot hot!! ;)

Where can I find your Motortec Features? I'm not having any luck finding it.

A video on making flow better thru transitions would be very valuable. 😀

Thanks for your bbc book build hp on a budget. I was always told rectangle ports are the heads to use. So after reading your book I bought afr 265 heads and a camshaft you specd from Terry Walter's. Thanks again. Hope to see more bbc info and watching you and Andy's videos.

Thanks!

After 350ft per second, you're in the realm of compressibility the flow starts fighting itself.

David is so smart

Good information as always Sir 👍.

Come on folks , it seems ... only one in ten viewers are giving a 'like' by hitting the thumbs up . We can do better , yes ? There is no man more deserving than the mighty David Visard and the charitys he serves aswell. ❤. If we help those that help others , the world is a better place. 😊 .Here is a pun ! It is im-port-ant 😂. cheers everyone .

I seen it actually work that way . During the 80's and early 90's , an old timer racer sold me on this. Everyone was stuck on port flow volume. BBc rectangular heads where 355 cfms and larger. Old timer showed me the way of port velocity of Bbc oval port heads. Oval port velocity flowed better then Rectangular heads. Big heads where high rpms , oval port velocity was better lower to mid rpm. More usable , responsive engine for the street. Also learned smoother ports on intake side was not better. Always great videos.

Perhaps at the planning stage of the heads would leaving the inlet valve diameter std and putting in the biggest diameter exhaust valve as possible and machining as needed. Just thinking this would help the imbalance.

I need a porting school

Place an electric diagonal fan on top of a piston in an operating cylinder. When the piston is at BDC on the intake stroke, the diagonal fan will generate a lower pressure area on top of the piston attracting air to flow into the cylinder through the intake valve even though the piston is rounding BDC and moving toward TDC. The spinning fan will obviously encourage air to flow into the cylinder until the intake valve closes. Remove the diagonal fan and replace it with high velocity swirl energy generated by a purposely designed intake port and it will act exactly like the diagonal fan and allow air to enter the cylinder by increasing the velocity and lowering the air pressure even though the piston is moving toward TDC until the intake valve closes. As opposed to a lazy/large flow/low velocity port with no swirl energy that allows the air pressure in the cylinder to equalize with manifold pressure at BDC and the rising piston will simply push all of the air previously captured, back into the intake port before the intake valve is closed. No ram effect, no volumetric efficiency, no power. ☺

How do you measure back pressure and what steps to take to reduce it some.

The guy who ported my heads complained about the valve size being too big. He like to see smaller ports and valves than what one normally see on different port videos. He mainly works on engines for professional rally, rallycross etc. Considering Darin Morgans formula for cfm demands one realize that many heads flow more than enough. Thats cid x rpm x 0.0009785/number of cylinders. That works out to a port on a 350 only needing around 256 cfm at 6000 rpm! That means there are a few other factors in play in a head deciding the horsepower other than flow. Things like shape, surface texture, chamber size/design/orientation, etc..

509 TRUCK BLOCKS have supetior alloy . Its not as high as the bow-tie offering but about half way . Theyll hardly rust after machineing . Thats a BIG CLUE indicateing higher nickel content . Theyre also harder than production blocks are when bored before ck-10 finished . My findings , dont care what others say . I found this verified Chevrolet data years ago . Theyre better blocks if core shift isnt a factor .

DV can you do a video on induction port and manifold tuning? Ie induction length vs pressure waves, plenum vs no plenum, variable induction systems, etc?

Hello david, Is there any truth in putting dimples in port walls .?

David this would be a fairly easy fix & fill on the 4.8 or 5.3 ls cathedral ports and the truck intake manifold . Nothing is being done with this on these smaller ls engines by Anybody !!! Its throw your wallet at it and forced induction . Big deal !!! Thank you for this tech being made clear . Chevy has made this easy to do . I appreciate your confirmation of my observations on this particular application which is very very similar to your shown example .

Just curious as to what % you like to see for the bowl area to valve ratio too please

Another jewel found only here. Much thanks.

Thanks for sharing all of your hard work!

Thank you David and Andy

Very interesting stuff, thank-you!

Thanks!

How is port volume measured and how can it be used to compare different engine families? If all you’re working on is SmallBlock Chevys port volume could be used to determine the right hand for the job. Now compare that to a Ford FE head which has a much shorter intake port than the SBC, and tell me how you can compare the heads four the two engines. Even comparing an SBC to a Mopar LA engine won’t work because the Mopar’s valves are centered in the combustion chamber and the Chevy is not. It seem like somebody took a term and started throwing it around like rating car speakers in watts instead of efficiency.

I want an oil geek shirt too!

I've read your SBC book enough times over several years I needed to duct tape the cover. All while buying many recommended parts and brands along with your spec cam from Lunati, I'm very pleased, did the go, now time for the show. But DV, you have to do something about these full length ads and not being able to skip after 5-15 seconds, please!!!

Don’t let the centrifugal force weight you down! Loose weight and run more freely! Weeeee:)

Thanks again for the great information on cylinder head ports and manifolds.

If only Ford "Sewer Pipes R Us" Motor Co had known this when they designed the 427 Tunnel Port, Boss 302, Boss 429, 351C 4V, etc...

Thanks DV

Lake is more than awesome

Thank you Mr. David Vizard for sharing your experience and knowledge!

More great stuff! Thank you DV

What's your other channel?

Early Holden V8 firing order is opposite to Chevy V8 ! 😮thanks for sharing, all the best to yous and your loved ones

Thanks, DV. v/r wh