Super porting GM Vortec exhaust ports

Most Vortec porting video's leave much of the Vortec's heads potential untouched. Here DV reveals porting moves and the flow bench results in detail. To get these ports to really deliver it is necessary to improve not just flow but also port velocity and port energy. This is part 2 in the Vortec porting series.

[@thatcarguy2778]

I got the chance to talk to David at pri right after his surgery a few years back. Super smart dude and all the big names were in the class he put on including Ed iskenderian. Would love to just sit and chat with him again sometime.

[@johnelliott7375]

Encyclopedia of the racing man, myth , and legend of the winners 🏆 circle. Plus many people who have been there or built them, because of this man and his teaching. God bless you David and I hope that you are having a great evening. Time for me to enjoy and watch the video production.

[@rogerstill719]

I couldn't have said it better myself

[@brracing7861]

It's a shame David Vizard present Channel is difficult to find now. Thanks for latest Video David.

[@deanstevenson6527]

Message to Mr Vizard. It's nice when expertise born in from Africa, fettled from English and French Aerospace, lands in America, and does porting work on 23 degree L31 heads. The dramatic irony is that working SBC heads in 1969 showed your developing skill set, but to add it to an already vastly improved iron SBC head 43 years on, that's awesome. And remember, it was a symmetrical port Cleveland lover that told you that. No Kiwi Ticks Required.

[@bcbloc02]

This video was edited to be paced about right. Looking forward to some new stuff. I hope you are feeling better!

[@mohanperformance.enginerd.1308]

All good information. David has alot to offer. But I think the real question is how the exh port would function when flowed at 1000 deg F and 2 or 300 psi of discharge pressure along with sound waves reflecting back and forth. Maybe a valve in motion as well. That would be an interesting test if we had that flow bench that can test it that way. I suppose a Dyno is that tool. Atleast we can validate changes in that way.

[@techroma1984]

Well yes, the transient situation also plays into the design but this is good advice because it shows you how to keep velocity up in the port (increased flow rate) during critical moments like low lift and high lift. Your scenario can be simulated in Solidworks or Ansys. Try to find a combustion pressure graph for a similar engine for data to put into it, model the valve and allow it to move according to the cam profile, etc. Many examples on KZbin.

[@obbyjep7597]

Awsome, this stuff is very useful I'm learning a lot from your vids and some old books, I have your how to build a sbc book I think it's from 70s . Thanks DV

[@DesignForVision]

Hi David... Would extending the port on a small block Chevy with a half inch piece of aluminum meticulously matched to the head before it goes into the header have any advantage for port flow? Also with small anti-reversion cones in the header right at the flange have any advantage when using a solid roller with a narrow centerline and a lot of overlap... Thank you for all you do for us privateers building race motors for our family racing team. Jolly good show!!!

[@Christopher-re2hl]

Hello Mr. Vizard glad to see your video. I have a question about a cylinder head but I don't want to bother you with it because it's an oddball and I can't find any good information on it as to why GM did that a long time ago and that's probably why nobody wants to fool with them and would rather LS swap the whole engine and I understand because when I look at these heads it looks like the exhaust bowl is offset from the throat towards the cylinder wall. The intake is the same as any other head but the exhaust bowl is difficult to figure out and why it was done like that from the factory. Someone told me those heads are tricky and different to get them to flow better unless I have a flow bench and not to mess with them too much. I think I should send them off to Butler and pay about $2000.00

[@lynnrunningdeer7364]

Wow😳. Several days in a row🤗.

[@tysdrift2404]

I just ordered one of your books I'm looking forward to reading it but a question that I have is a D shape exhaust port going into a round exhaust header do you blend them together like gasket matching? Or do you leave the rige in there?

[@sumguysr]

I love your videos David, but all the transitions, effects, and text are very distracting when I just want to listen to you. It'd be nice if you mostly just used them between segments, like a paragraph break or new chapter.

[@mrkultra1655]

Thanks David. What are your thoughts on the old Chevy “Camel Hump” Fuelie heads?

[@TheProchargedmopar]

👍💪

[@pmd7771969]

Small gains for big aggravation

[@rogerstill719]

Can ANYONE tell me why/how the brass float in my 4779 Holley was so flat that it cut off the fuel supply