David Vizard's PowerTec 10 EP 13 Part 2 Super Porting Vortec Exhaust and all other 23 SBC heads

hi david weissard here and you are watching power tech 10. so what's the subject of this episode of paratac tan [Music] so if you look carefully you can see that the floor of the port still has little casting witness marks on it as i said i've just taken off enough to clean up also you can see the casting line there at the side of the port of course this is tipped on end and this would be the cylinder center side you see almost nothing has come off there it's all been off around the guide boss all that work on the port and here i've cut it in half but at least i can now show to a far better degree how this is cut away here right this is this centers of side of the cylinder center side of the port right you can see how that's cut away and keep in mind the width of that there now let me show you the other half we're now looking at the cylinder wall side of the port notice how much wider it is here than the uh other the side that's on the cylinder center side of the port bigger cutout here it's cut away here more there's more room for air gases rather to flow down here and out so far our testing on this here has revealed that what we've done so far has not got enough bias on this side here and it needs metal out here as well we can't cut much more out of here because that's going to be where the gasket is right so let's see what other obstacles we might have here well i think the last point of note here is that it gets thin here so be careful how much you cut this away this point here is about a sixteenth of an inch lower than the original stock platform that was there so you can see we're limited here one test i'm going to do on this here and i'm often asked this is what happens if we cut away the guide boss so that the ports more like this well we can actually do that but let's see what it does for flow and then i'll run through what we need to do to make such a move practical our last test number five is with the port cleaned up that means we've gone in done the valve seat done the area ruling on the seat and the part before not just before and just after and cleaned up the throat etc and made a tidy port of it basically nothing has come off the port floor other than just clean it up and port bias has been continued on out to the manifold face where it tapers off to the original shape so our external port shape hasn't changed here's what that looks like in real life again let's check this against number one and we can see just how much just so we can see how much we've gained here's our test five versus test one pretty sizable gain in [Music] flow valve lift will be about here typically so we've achieved all that although we won't necessarily use it but [Music] our port velocity has gone up a bunch quick now let's look at the port energy and see how that's gone up it has gone up drastically so we have increased the flow and the velocity to the extent that the port energy that's the ability the port has to extract exhaust from the combustion chamber during the overlap period and send a pressure wave back has gone up by this much so we've done pretty good there but we've still got to go with a bigger [Music] valve [Music] [Music] point to note here is how this turns into this here we'll be able to see that much more clearly when i section through the head here also note the valve seat there you can see just how much of a turn there is above it now take a look at the intake you'll see that the edge of the seat here is actually a sharp edge to the chamber that's a 30 degree cut there which has got a an edge just there so we have the the radius at the bottom of the intake with a sharp edge at the top the emphasis with the exhaust is a radius on the top because the exhaust has got to go out note the chamber shape this is a virtually finished chamber shape and note this area here is still untouched remember this is a no-go area in this shot you can see the valve seat i've cut this just before i've got to the point of blending this top curve in also in this shot you can see how this is cut away the flow predominantly is going out this way like that so this needs to be cut away notice how the guide boss slopes and how small the guide boss has become let's turn around now and look at this side of the port you can see that although there's a generous cutout here and the ports uh widened across here it's not as much as on this side uh this is the area where we have to be careful not to go through just here that's about the limit the exhaust seat is cut lower than the intake when the two valve seats are level the exhaust would be here actually when it's seated it's there so you can see just how much that's deeper than the intake that allows us to put this curve on here which i'll show you later remember when we were velocity probing i said that it was fast either side of the guide boss mostly just here from this if you make a comparison with the uh the stock uh guide boss you'll see that this has been cut down drastically in here and care has been taken to streamline it just here we've made it deeper and smaller across here also we bias the port in that direction there remember the flow is out like this so this boss here if you look at it is deeper this side than that side right that's so we conserve as much uh or we minimize the amount of metal we take out the port so as we keep the port energy up right so now let's see what this does on the bench this part has already been largely finished right based on what we found from probing the stock port but we've still got to look at it downstream right so that's what we're going to do now [Music] often valve form especially the back side of the valve for the exhaust can greatly affect the flow we see on the left here is a more tulip shape than the one we've been currently using on the right when we installed this the flow increased measurably here's the graph of the one valve versus the other i should point out before we go to the graphs that these numbers here were generated by a clean up on the seat and the installation of that tulip valve i just showed you here's the before figures here here are the after figures let's take a look at the cd curves and we'll see just what effect the seat work together with that tulip valve did forget the blue curve here that's the intake and it's not one that we were currently working on but here we can see the difference in the efficiency of the exhaust this peak here was the result of dressing the seat a little better however as we get down here this is all due to the form of the valve and you'll see it comes up but then it levels out my reckoning is that we could get this to go up like this but the casting gets a bit too thin this curve here flattening out represents a situation where it indicates we don't have enough port bias these two curves here represent the port energy the flat valve the tulip valve as you can see our port energy increased all the way from about 50 000 on [Music] and it's looking pretty good but let's take a look at the port energy density that's where we remove the effect of the size of the port and just look at how efficiently it's generating port energy so let's quit this go to port energy density calculate graph [Music] well these numbers might not mean a lot to many of you but from experience i can say that this curve here which generates at 700 lift 26.3 foot-pounds per square inch per foot length port is very good so we can expect this port to function pretty well in practice well here we are hacking our way through the cylinder head hopefully i've got this blade aligned with the center of the valve guide sometimes not quite as easy to do as it may anyway we'll be through this in a few minutes so we'll be able to compare the fully modified port to the big valve against the stock [Music] [Music] now there are possible downsides on doing a max effort port on a vortec casting i use this particular casting here because i sonic checked it beforehand and i could see it was thin here and it could possibly go through as you can see it's only left a thin wall there usable but barely anyway you will find that most ports are about 40 thousands wider here but this is the dodgy bit here what i suggest you do well take less metal off here and and live with the fact that it's going to decrease your mid-range flow slightly it has almost no effect the radius here on the high lift flow the air is already well separated from this and at high lift the majority of air is going down here and you can see there's plenty of metal to generate that form what we're looking at here is the cylinder wall side of the port cut away much more here because the gases are going out this way and we're focusing on trying to remove metal here also we're trying to make this curve here as big as possible here we take off metal because it's going fast as we did on the other side of the port at this point and i think that's about it for the port but let's look at the seat area from the quench this is the quench pad here and this is the scavenge plateau here notice how there is a radius into the seat which is just about there the reason for this is we want the gases to be able to escape from this area here when the piston comes up close and make it round the corner and energize this area of the port here do the seat like this and that is just what it will do [Music] a point here i need not to overlook i've cut quite a bit away from the spark plug boss here this actual deal here is about a thread and a half shorter than it was stock so when we install spark plug we need to put two washers under the spark plug to get the body of the plug to be just here also it is important that you use an extended nose plug that puts the point of ignition right about where the end of my scribe is there that's going to work for us well unfortunately it looks like we're going to have to draw the line at about 20 minutes for this video here's the problem i have not got to the exhaust ports on aluminum heads yet i guess that's the bad news but the good news is this is all running so well here i've decided to do a part three on the exhaust ports or rather aluminum heads and the exhaust ports of such now this is going to give me 20 minutes to do it instead of just a few scant minutes as would have otherwise been the case we'll be able to deal with things like smoke traces as well as the normal airflow we might even get around to doing some bulk flow tests which i don't think anyone ever talks about that but what it is is it's a down and dirty way of finding out where the bulk of the air is going without any expensive equipment i'll see if i've got time for that so i'm going to leave it to you to hit the subscribe the like and ring that bell that's your job my job is to provide you with the best technical info on youtube i'll do my job you do yours thank you for watching [Music] this is [Music] you

Channel: David Vizard Performance

Views: 18,057

Rating: 4.987431 out of 5

Keywords: Cylinder head, Edelbrock, IOP, Induction optimization program, Porting, SBC, Vizard, chevy, performer rpm David vizard

Id: E2l72kGYnpg

Length: 19min 25sec (1165 seconds)

Published: Wed Jun 02 2021