'99 Mustang build

6 Shooter

Well-Known Member
The upper is pretty easy to make and then weld up. Just do not have any time. If you have an interest in doing this project, with your email address, could send you a bunch of under construction photos, dimensions, and tips/tricks. The absolute starting point is the lower intake where the porting is significant. And, some re-routing of coolant lines is required. You also need access to an aluminum welder/welding. If you decide to go this route, suggest you decide on a throttle body beforehand. space is very limited when figuring out how to get idle air into the TB and have room for it. I used an 80mm Wilson TB and actually have a spare part which attaches below for routing and hooking up the IAC which you can have to use or fabricate a new one.
 
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BRN2RUN

Active Member
I'm still waiting to get my heads back (machinist is still backed up), but before I had dropped them off, I had read this:

http://hotrodenginetech.com/pipemax-creator-larry-meaux-on-race-engine-head-porting/

I had originally polished the surfaces, but then I had decided to roughen up all the textures, too, with a rotary rasp, which creates a rough enough texture that you can feel it when you move your finger across it. I'm doing the same thing in my Super Coupe heads.

I think that 60 grit cartridges (very rough by sandpaper standards) is still too fine of a grit to really motivate surface air movement in the boundary layer. As per NASA, airflow along the surface of anything is zero:

https://www.grc.nasa.gov/www/k-12/airplane/boundlay.html

Consider this: when I took off my self ported/ polished intakes last year, imagine how frustrated I was with the EGR section having left a layer of carbon on there. My Moroso air/ oil separator kept probably 95-99 percent of the oil blowby out of them, but the carbon bugged me. Polishing likely improves some aspect of performance, but the problem is: it won't last. A slightly roughened texture should last, and that's probably why Larry is seeing a bit more power out of his engines, along with less fuel used for a more efficient burn. The combustion chambers are still a part of breaking up and atomizing fuel until it ignites, and though there's likely less carbon buildup with it (or maybe not: think of the soot covered intakes at the EGR section), once you fire up the engine, the polished surface won't last very long. The other frame of mind is that the mindset of an intake runner's air moving too fast in that the fuel falls out of suspension by sticking to the walls, possibly the same thing happens in the combustion chamber and that it actually needs to be slammed against another rough surface that breaks up and vaporizes the droplets up even further.

If we apply the polished intake/ EGR theory to the exhaust port, it too will get covered by carbon and a roughened texture should last through that. I suppose the worry is that there may be more carbon build up because of a roughened texture, but when Larry says that he observed bone dry exhaust ports, he was seeing less un-atomized fuel which would indicate a better burn, anyways, and one would assume less carbon (with a proper tune on the car).
 

BRN2RUN

Active Member
I had got a 91 performance tune from MPT Tuning last year, and Ken does a great job with these. He puts the spark all the way to 50 or so degrees of advance at cruise speeds, whereas Bama puts it to about 40 ish (and that's even on their 93 race tune). While the full throttle performance is about the same as Bama's (27-28 degrees of advance at WOT), the seat of the pants feel at cruise speeds is noticeably faster and the car feels WAY lighter, as it should with 10 degrees of advance. It feels like a gear swap. After I get my cam and heads on the car, I'll get him to do a 93 race version. I had taken a screenshot of the datalog, and you can see that the spark advance is right to the MBT spark (MBT spark being optimal advance for the most power).

Ken Osborne MPT  91 performance tune 1000X562.jpg
 

BRN2RUN

Active Member
Here's some string/ flow testing pictures, below. The Slurpee cup is definetely MacGuyver, but it's almost the same size as the cylinder bore. Don't laugh! :) Here you can see where the air flows the strongest through both ports, when the string (air wave) is longer--the short side flows a lot of air and the long side (opposite of where the strings are coming out of, by the spark plug) is much more difficult to move air. The SC single port heads have a much more even distribution of flow--they still want to flow quicker on the short side, but it's not as difficult to get the string to move through the long side on those heads:

stringtesting1.JPG


But the problem with the split ports is that while you have two ports flowing air, eventually the air streams tangle up with each other. How long they tangle up with each other, I don't know--this is no simulation of an actual piston under vacuum/ pressure circumstances, nor the appropriate valve lift for the piston distance (vacuum head at the top of the Slurpee cup that can be moved around to vary vacuum source within a cylinder). But it does eventually interfere with each other at some point, when the air streams get longer. This is probably what Ford tried to address with the IMRC valves as a crude variable cam timing, but it's something that TIVCT properly rectifies:

stringtesting2.JPG



Here's a better look at a low valve lift, and where the airflow is strongest, where there is no interference between the air being moved through the two ports, when the air wave is short (string is short):

stringtesting3.JPG



Here's a shot of a high valve lift, and the path of least resistance that the air has to take--the straight string is the shorter, upper RPM round port, and the string that's viewed sideways here, was caught in the photo in the middle of chaotic, swirling action, as we can see from the same high lift with the same vacuum. That port is the longer, low end torque port, and this swirling action may be good for mixing with the fuel, but its unclear how much upper RPM, high valve lift damage that it may do from having a stray air stream whipping around. Again, the vacuum source isn't likely to correspond with the piston's location in relation to the valve lift (nor the actual swirl in the cylinder due to the rotation of the vacuum source as the piston moves down), but it does show that the low end torque runner's bends and design aren't as good for creating upper end horsepower. You can also see that the outer edge of the valve impedes the straightest path possible for the air to go:

stringtesting4.JPG
 
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BRN2RUN

Active Member
This photo was a work in progress photo, not of finished ports. In red, I've outlined the high velocity area in the exhaust port. I'm guessing that this is removed by most people (including pro head porters), as it looks like an impediment to flow. It likely is, however, the long side flows very poorly, and what this ridge does, is speed up the airflow and send it to the sides of the valve, and out the short side. The string circles the valve, extremely quickly on the sides and on the short side. Removing that ridge probably picks up gains on the flow bench, but a ton of velocity will be lost. On my original head porting that I'd did a couple of years back, this ridge was removed, and compared to this new design that I've done, the flow on the sides was much lazier.

Essentially, from what I can tell with the string testing, is that removing that ridge will basically have the same effect as losing at least one of the angles of the factory valve job (and maybe closer to two), because the multiple angles speed the airflow up in these heads so that--even though the exhaust ports are small--they're very efficient, and why simply hogging out the ports doesn't yield the gains that are desired on these heads. If that ridge is removed without installing a bigger valve to flow more air on the short side to compensate for the loss of velocity, that's where some of the port work has gone wrong, I think. In comparison to single port SC heads, when hooking a vacuum up to the exhaust ports, the exhaust velocity is much weaker, though the airflow is much more balanced on all sides, and it's not as difficult to get the string to move on the long side.

In other words, consider this ridge to be a kind person gently persuading people out the closest door--the path of least resistance--when a building is on fire. Removing that ridge removes that person, and that causes people to run around scrambling for that door....if only they knew where it was. :) Directionality is key in these heads.

highvelocityareaonmustangheads.jpg
 

BRN2RUN

Active Member
I'd bought a cam, beehive valve springs and hardened pushrods from Dave at Super Coupes Unlimited (he also works with the split port engines). Cam is 218/224 at .555, and should be on the way soon. Today, I'm going to re-port the lower intake manifold, as I'm going to try to grind down the EGR boss/ area as much as possible, and try to have it not impede flow as much. I'd noticed that it's on the short side (the path of least resistance), so grinding it down and smoothing out that whole area should improve flow a bit. I'd also re-ported my upper intake by removing probably 2-3 mm in diameter, and had gave it a roughened rotary rasp texture (along with the throttle body and throttle blade) and will be doing the same to the lower. It seemed to pick up some power. I'm going to datalog it and see if it had dropped the vacuum at all at WOT, and by how much. I think that it was at about 2.1 to 2.3 inches of Hg at WOT, before.
 

BRN2RUN

Active Member
Here's a couple of pictures of my re-ported lower intake manifold, with a roughened texture to promote more airflow along the boundary layer. It had gained noticeable power, because 3rd gear where it's a 1:1 ratio used to be a slug for me, but it pulls hard in 3rd now. I had re-did my upper last week where it had seemed to gain something, but I can say that the lower intake seems to be where the greatest gains are. What I did was concentrate more on the EGR area, to give that area more of a downslope ramp (a steeper angle should be better), and a better area for air to manage. Also, at the head side port of the intake, I had removed a lot of material, especially on the high RPM runner/ port (the round one), as it has a natural bell shape to it that I had kept, but opened up much more. My initial port work, I was somewhat concerned with opening the ports up too much, but I can now say that a lot of material can be removed with no worries of airflow slowing down too much, especially on stock heads/ cam. I tried to get the lighting in the photos to accentuate the roughened texture.

This is what the upper intake sees, going into the LIM:

Lowerintakemanifoldreportedwithtexture.jpg


This is what the head sees:

Lowerintakemanifoldreportedwithtexture2.jpg
 

BRN2RUN

Active Member
It lives! It fires up!!!! I had finally installed my heads and aftermarket cam myself, and there's no leaks or anything.....it's running smoothly (other than a low vacuum at idle right now). I'd only taken it a few blocks and driven it normally, but I can say right now that it definitely has more balls in the low end. The vacuum is lower than it should be at idle, so I'm going to datalog some things and dial it in properly. I'll have some pictures and tutorials up very soon. There was some unavoidable broken bolts (rusted, weak), busted knuckles and some other interesting detours that were out of my hands, but it feels that much more satisfying having been dealt those curveballs and getting everything together as it should be.
 
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