1500 FI Cylinder Head Intake Porting

Discussion in 'Workshop Forum' started by beezee, Nov 10, 2019.

  1. beezee

    beezee True Classic

    I have a 1500 FI cylinder head that I am making some gentle modifications to in the interest of a bit more power. I have already had the head milled to increase the compression ratio, and the next step is to clean up and modify the ports a bit. Now if I remember correctly, there used to be some pictures on this forum showing how to modify the 1500 cylinder head intake ports to get better flow, but it seems the server that hosted them is no longer. I think they were here:


    Did anyone save the pictures or no where I can find them?

  2. Dr.Jeff

    Dr.Jeff True Classic

    Sin City
    Brian, I have some pictures but they are not very detailed. I believe most of them were from Steve's reference (your link). All were in various threads on the forum at one time or another. I'll post them below.
    Keep in mind these pictures are rather radical port mods. You may not want to go this far (e.g. removing the complete valve guide boss, etc). Naturally it depends on the specific build and intended use, but I seem to recall you are building a normal street use engine(?). Removing everything like these pics show has drawbacks...like everything there are tradeoffs.

    When I did mine I found the biggest thing was to make the ports all match one another. Between the head and lower runners and between the lower runners and upper plenum (for a FI engine). Also the same for the exhaust manifold. The factory castings were rather far off from one another and needed a lot of work. I recommend adding pins to locate the head and manifolds so they will remount in the exact same positions every time (there is a lot of slop in the standard mounting). Also the castings were quite rough and had a lot of casting flash, etc to remove.

    Here is what I had saved:

    soo parts 1 and 2 done.jpg soo new valve seats.jpg soo head done.jpg port view number 4.jpg port shape 4.jpg byron after porting.jpg

    I am of the impression that unless you have a flow bench, lots of experience, and considerable knowledge about the science involved, it is much easier to make things worse than better.
    I'm not sure how much you have ported in the past but I found that carbide burrs are not really the best tool for mild clean up work. Instead things like cylinder sanding drums, flap wheels, various shaped abrasive rolls and similar tools worked best:

    1UH58_AS01.jpg images.jpg 41Lq8jDsNJL.jpg
  3. beezee

    beezee True Classic

    Thanks for the reply Dr Jeff.

    I'm not planning anything as extreme as those pictures. The head has to work with the stock Bosch FI, and I wan the engine to behave nicely on relaxed drives, but with a little more performance at higher RPMs. I have a MWB 223 cam to go along with the head work.

    I have started cleaning up the ports using sanding rolls. I read that removing material from the intake port roof is beneficial, so I would like some more details on where the material is removed.

    I like the idea of pinning the intake manifolds as they can move around quite a bit.

  4. Dr.Jeff

    Dr.Jeff True Classic

    Sin City
    Hey Brian, I have lots of thoughts following my experiences of porting a couple of X1/9 heads. But these are just my personal opinions as I am not a porting expert.

    That's what I recalled from your prior posts, and what I wanted with mine. So like you, I decided not to remove the guide boss and make a big bowl like in those pictures. I realize that is the way to get the absolute maximum flow under peak conditions, but it's my understanding it will also result in a loss of lower end torque. With the mild cams we are running (I have the same one you have), the factory FI system, and for normal street use rather than racing, torque is more beneficial than peak HP (in my opinion). So I agree with what you said, extreme porting may not be the best answer.

    I've read various views on this. Porting is one of those topics with more questions than answers. I suppose it depends on each specific head/engine design in terms of the ports, combustion chambers, valves/guides, runners, pistons, etc, etc.

    I recall reading comments by Steve C that removing roof material wasn't the best approach. But this was part of his description to remove the guide boss and create a large bowl (like in the pics). So I think his goals were very different and perhaps therefore the technique would also be very different? I really do not know, but perhaps if the guides and bosses are left in place then maybe opening up the roof is the thing to do? This is where I said that without a flowbench, proper testing equipment, the right scientific knowledge, and lots of experience it is difficult to know what's best.

    As I've been going through my engines recently, I found that one of my heads had already been ported by a prior owner (everything else was completely stock so I was surprised to find this). Their approach was to open up the roofs, but unfortunately it wasn't done very cleanly. The rest of the head was in excellent shape so I decided to continue the same path and finish what had been started. I tried to make each port as smooth of a transition as possible around that otherwise sharp corner, where the roof bends from the runner to the valve seat. Due to the existing porting work that had already been done I really did not have much option on the specific radius, contour, etc, so I just tried to make all of them the same and as clean as possible. Frankly it ended up being a lot of material removed across there. Maybe too much, no idea. And really I'll have no way of knowing because I won't have dyno testing or other comparative data to look at. But I can say the change in terms of overall volume across that section (i.e. the size of the opening) is definitely noticeable, especially with respect to the guide boss. I'll try to get some pictures later today and post for you to see what was done. But remember I'm not saying it is correct or beneficial, just what the cards dealt in this case.

    I think (just my opinion) the overall best approach might be to not try and remove any material (i.e. reshape anything) beyond simple cleaning up and port matching. However that may not be as easy as it sounds. For example on all of my FI intake manifolds the castings are very crude. There are rather deep valleys along the long axis of the runners where they were cast. If you use a drum type sanding wheel so the circumference is maintained in a nice round shape, and move it along the sides of the runners (long axis), you will find that a LOT of material would have to be removed to eliminate those valleys. At which point the runner will no longer be round (in cross section), but oval. And to make all four of them the same and consistent would be difficult. I started out attempting to do this but once I realized just how extensive the casting defects go, I decided to not try and eliminate them. Instead I made several lighter passes along the walls to try and blend them a bit (although that wasn't completely possible either due to the curved shape of the long runners).
    Another example I found was on the head where the valve seats are fitted into the ports. There was a lot of overlap at the bottom edge (the side of the seat that faces away from the valve face). I tried to make those as flush and smooth transitions as possible, but it would require a rather large amount of material removal from both the seats and ports to get them completely smooth; possibly making things too thin/weak in places.
    Also I found the head castings are very porous. Some of my heads were worse than others. As I cleaned up the ports I noticed some of the "holes" (porous defects) would disappear while new ones would open up (as you exposed new material). So I did not try and make all of the walls perfectly smooth, it would have been a losing battle.

    I suppose there really is only so much that you can do and hopefully a little bit of mild clean up is better than nothing. I'll see what pics I can get and post later.
    Cratecruncher likes this.
  5. lookforjoe

    lookforjoe True Classic

    The easiest approach is to simply follow the casting lines and clean it up to remOve all the rough casting and port match. To achieve the runner opening Steve created requires welding additional material to the underside of the runner (!)
    Dr.Jeff likes this.
  6. Dr.Jeff

    Dr.Jeff True Classic

    Sin City
    Based on everything I said in my last post (following my experiences), I'm of the impression that the biggest benefit that can be achieved is from port matching (short of extreme porting). As I said, all of my ports were very far off from matching (as stock). Including on the intake manifold from the head to the lower runners, from those lowers runners to the upper runners (plenum), and on the exhaust from the head to the manifold inlets and from the manifold outlet to the downpipe. Also as I mentioned, the transitions from the valve seats to the ports in the head needed to be 'matched'.

    One major problem I found is that the stock mounting arrangement for the manifolds leaves a LOT to be desired. There is a lot of possible movement each time the manifolds are attached, which moves the relative locations of all the port openings (as listed above). So I added pins (dowels) between the head and lower runners, and between the lower runners and upper runners/plenum to try and help place them in the same location every time. Honestly I still find that there can be a slight variance even with the pins, but it is a whole lot better.

    For the ones between the head and lower runners I decided to kill two birds with one stone. I also wanted to plug the water passages that go from the head to the intake manifold. So I made those plugs out of stainless bolts and extended them up in length to also act as the locating dowels for the manifold. The holes in the head have been threaded to install them. Here is what they look like:
    002.JPG 003.JPG 004.JPG
    What's nice about this approach is the manifolds already had neat markings (stains) of exactly where the water openings are so you know where to drill the matching holes.

    For the mating surfaces between the lower and upper runners I used rollpins:
    009.JPG 005.JPG

    On the exhaust manifold I found it wasn't as practical to add pins/dowels. With the position of the studs and manifold mounting pad holes I found that if the manifold was moved 'down' as far as possible (i.e. toward the block, away from the intake manifold) when tightening the nuts, then it tended to go in the same position each time. This is due to the angles of those mounting pads relative to the studs. I discovered if the exhaust manifold wasn't moved as far down as possible then the mounting pads between it and those for the intake manifold could contact one another. That will allow heat transfer between the very hot exhaust manifold and (hopefully) cold intake manifold. So there really was only one good position to mount the exhaust manifold (as far down as possible), and that seemed to be the same location each time by pushing it against the studs. So that is where I port matched it (also very far off in stock configuration).

    By the way, there has been a lot of findings showing that if the exhaust ports on the manifold are slightly larger diameter than those of the head, then it creates a slight scavenging effect. Steve C found that due to the configuration of the X's ports, if that enlarged opening (on the manifold) was located more toward the lower edge of the head's ports it further benefited the exhaust gas velocities. So by locating the exhaust manifold as far downward as possible (as just described), it made it easy to make the manifold openings slightly larger on that lower edge. Basically the port matching is then done to the upper portion of the manifold to match the head, leaving the extra diameter at the bottom. Hope that made sense, let me know if not.

    As for how I did the port matching. I do not believe in using the gaskets as templates. I've found the gaskets are not that accurate and tend to be off from where you really want the openings. Plus they can move around a lot making it difficult to replicate the location on both sides. Also if you make both surfaces match the openings on the gasket, they tend to be larger than the rest of the port/runner diameter. This creates a 'bubble' in the middle of the flow path, which in theory will disturb the gas flow. Instead I bought a tube of that blue greasy transfer marking compound stuff:
    It requires a lot of on and off testing with it to get both surfaces to match. First work on one side (e.g. the head), then work on the other side (e.g. manifold), back and forth until they are the same. Basically you are removing the "high spots" on either surface until the holes match. With a bit of practice this marking compound is easy to use, but a bit messy. Having done it I believe it is not possible to get a true port match without it.
    Last edited: Nov 10, 2019
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  7. tonyism7

    tonyism7 Daily Driver

    New Jersey
    It's unfortunate that a lot of the picture links in the ultimate sohc thread are dead, but you can still see most of the pictures. Click on the link for the dead picture. It will open a new page that doesn't load. Usually, the address of the new page will be something like:


    If you change the ".org" section to ".cc" the picture should load. The new address will look like this:

    beezee, PaulD and Dr.Jeff like this.
  8. Dr.Jeff

    Dr.Jeff True Classic

    Sin City
    Hey Brian, long post here. But as I promised earlier here are some photos of how the modified ports ended up on one of my heads. This is the head that someone had previously tried to port (incorrectly). I did not try to redo it, but rather I cleaned up what they had (crudely) done and tried to make the best of what was left. I'll add comments with the pics to explain what went on. These pics are actually of a exhaust port, but it is identical to the intakes (more on that later). And they after I've reworked it, but maybe it could still use a little more polishing (although I'm not a big believer in the benefits of polishing ports for a street car).

    First I should clarify the use of the term "roof" as I referenced it before...we may be thinking differently. I'm referring to the portion of the port that is on the 'short radius' side of the bend between the runner and the valve opening. It is the wall opposite of the valve guide. I believe the theory here is to allow more space around (opposite) the boss for the valve guide (to help accommodate the intrusion made by that boss and the guide), in contrast to the removal of the boss and end of the guide. I suppose technically this might be the 'floor' when the head is sitting in its normal orientation? Looking from the manifold end of the runner this is where the prior owner had made some major changes - removing material to open up the neck and round out the radius of the bend (red arrow):


    In the above pic you can see that I also attempted to smooth out the area surrounding the valve guide (better radius the boss around the guide), but I did not eliminate any of the boss's support to the guide nor shorten the guide itself. I'm of the impression for a street engine it is better to keep the guide rather stock.

    Here is the same thing looking from the chamber (other) end. Again the red arrow is what I referred to as the 'roof', and where the changes had been made by the prior person. As I understand, part of this approach is to reduce the sharpness of the bend or corner. Think of a hard 90 degree square corner vs one with the corner's "edge" cut off to make more of a radiused bend:


    If you compare that to a stock head there is quite a bit of material removed across the "roof". Measuring from the guide to the modified roof, it is longer (taller) here.

    Looking once again from the runner end, here you can see what's left of the rather deep casting lines in the runner (red arrows). I removed as much of them as possible without destroying the runner. It is difficult to get the deeper/distal aspects of them due to the curvature of the runner and the guide boss being in the way. I also tried to remove as much of the bad porous holes in the cast aluminum throughout the entire port. The blue arrow indicates the guide boss that I tried to smooth/radius out (described with the first pic):


    Looking into the valve seat and port bowl area (below). The seats were not well aligned with the rest of the port/bowl. I do not know if this was due to poor assembly from the factory or if someone has replaced the seats and did not do a good job. But there was a lot of overlap and gaps as the round seat openings (ID) were not centered within the port opening (area around where the red arrow is, below). I removed material from the walls of the bowl in some areas and from the inside circumference of the seats in other areas to try and 'match' the bores (sort of like port matching a manifold). I also tried to straighten out the bowl's walls as it aims toward the valve/seat opening. This is what SteveC describes in his porting guide, allowing a straighter shot for better flow around the valve head and into the cylinder. The bowl walls on the three sides opposite the port (directly behind where the red arrow is, plus the two adjacent walls) are where you can do the most toward that goal. But it gets very tight as you get down by the guide boss (sort of where the tail end of the arrow is sitting here):


    Finally a shot of the runner, looking from the manifold end. I tried to make it as round as possible and eliminate the casting flaws. But I did not try to open up the overall diameter or make them significantly larger. Again, for a street application I do not believe that bigger is better, but rather maintain better velocity of the gasses. I did port match them with the manifolds. They were very far off (both intake and exhaust) and required material removal from both the head side and manifolds side. My approach to port matching is to retain the diameter across this transition and not make a "bubble" by opening them up to match the gasket (I described this earlier):


    As a result of the port matching, the manifold gaskets will need to be trimmed a little (some aspects of the opening ID). This is because of how far off the stock ports were from one another.

    Considering the head had previously been modified and that I had to make further mods to try and repair that damage, I was concerned that the individual ports/bowls were no longer equal to one another (each one relative to the others)...in terms of overall volume. So I used the CC'ing set-up that I made to measure the combustion chambers and measured the volumes of each port (in the head, from where the manifolds mount to the valve seats - with the valves installed). They all came out to within one CC of the others, which is about the margin of error with my apparatus. Although I used some lab grade equipment I had left from my old practice and I have experience in using such equipment, it is highly susceptible to error and each measurement will yield a slightly different value. So I am fine with getting an average of 1cc difference between all readings. According to what I've read that is well within the margin of acceptable tolerance.

    I do not know how good or bad this porting job ended up being. I do not have a flow bench. I thought about making one but decided it really did not matter, as I don't intend to experiment with a bunch of heads to refine the technique. Whatever I ended up with is what I have to use on this engine, so it really does not matter how good it is (or isn't). I wasn't prepared to buy yet another head (this one was purchased with the understanding it was a good stock head) and start over, so I just tried to make the most of what I had. This will go on the turbo engine and it is my understanding that porting isn't very critical with a boosted application (compared to a NA one).

    On a related subject. I had a great discussion about valve design with the head engineer from Manley Valves while at SEMA. According to him, on these engines the exhaust valve is already extremely large relative to the intake valve size. Seems the original design was not concerned with building any torque, otherwise relying on high RPM's to make more top end HP. The intake valve can be increased in size, but not nearly enough due to the limited room. He said he actually reduces the exhaust valve size in these cases to make the engine more drivable in street applications (i.e. more torque). I suppose that indicates it is more important to get the intake porting right than the exhaust side. However in my case I had already done the exact same porting work on all eight ports (the prior owner made the same mods to all of the ports). And as for modifying the valves to increase flow (e.g. reducing the neck diameter or flattening the backside of the valve heads), he did not recommend it for the same reason. He began offering a lot of technical data to support his view, but frankly the show is so huge that I didn't have time to sit and chat an hour with any one person - so I cut it short and moved on. But I thought I'd throw out the info for others to argue with. :p
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  9. beezee

    beezee True Classic

    Much thanks Jeff! Lots of useful information in your post...

    In regards to the valve seats matching the ports, I have found the same issues as you have, they are not well done. From my observations it seems that the heads came that way from the factory. It's not a difficult job to blend them in with a porting tool and an abrasive roll, which I have already done.

    I have read Steve's ultimate SOHC thread that states improvements can be made by enlarging the intakes at the port roof (around the valve guides), and it seems that you are of the same opinion.

    Steve also posted that a 3 angle valve seat cut will improve flow:

    "A top quality 3 angle valve job will make significant flow improvements at all engine speeds and valve lifts. Try and save money here and you may as well forget doing the job as the results will not meet your expectations. On top of the regular 3 angles, an additional 90 degree straight plunge cut to enlarge the throat of the valve seat will show significant flow gains. It is definitely worthwhile to have this straight plunge cut extend into the alloy head inside the valve bowl to make the straight run into the back of the valve as long as possible."

    So my plan so far is as follows:

    1 - Mill the head to increase the CR. I am aiming for 10:1
    2 - Clean up the intakes and open them up slightly in the area of the valve bowl. In addition I will try to match up the manifolds.
    3 - Install a MWB 223 camshaft which I already have.

    The goal is to eke out a few more horsepower while retaining the stock fuel injection. Once the mods are complete I will need to check the AF mixture to make sure the engine is not running lean. Any recommendations on an AF meter?

  10. Dr.Jeff

    Dr.Jeff True Classic

    Sin City
    From your last post I'm certain we were using the term "roof" differently. Your use is actually correct; the area around the guide/boss would be the roof when the head is installed. I was referring to the floor (area opposite the guide) as the roof because I was looking at it on the bench (upside down). So just to be clear about my head, the prior person actually ported the floor side, not the roof side. I realize that isn't ideal but I just tried to clean up what they already did, plus I did a little work on the roof. But it is my understanding in order to really change the roof you need to remove the boss (raised area) around the guide and cut the guide down to match the new roof height. That really opens up the bowl. It also allows you to better straighten-out the bowl sides toward the valve seat. However I did not want to go that far, plus as I stated the floor had already been modified. Hopefully in my case it won't matter so much - being a boosted engine. If I decide to port my other engine/head (which is stock-unmodified), then I might try removing more of the boss. That engine is NA (not boosted) so the guides aren't quite as important as with the added heat of boosted pressures.

    Thanks for confirming about the seats not fitting correctly in the heads. I have two other heads but haven't had a chance to start working on them yet so not sure how bad the seat fitments are. Therefore I was wondering if this one had been screwed up - especially after seeing how they messed up the ports. Really gripes me to have purchased what was supposed to be a good head from another forum member, but things happen. However if these seats are typical then that part doesn't matter.

    I've always heard the same about a three angle valve grind being best. Mine do not need to be ground so I am leaving them as they are (stock angle). Should I need to replace the valves (it's likely the stock ones will burn with boost), then I'll go to stainless and a three angle grind.

    With my build being a turbo I am retaining the stock compression ratio. But if I was building a NA engine then I'd shoot for no more than 10.1 maximum. I'm not a huge fan of higher compression for street cars; the quality of fuel supplies are not reliable, and I would not want to go through the hassle of running special fuels. Even 9.5:1 would be fine for me.

    I haven't purchased a wideband O2 meter yet, but I have been doing some research on them. Seems to be too many complaints about the Innovate products, so I'll stay away from them. I found a really interesting one that supplies it as bare components. You can mount the circuit board in any type of enclosure you want (to fit your individual build), and the digital readout is also a bare display that you can incorporate into your dash - custom style. However I discovered they only make it with the older style of sensor, not the latest self-calibrating one, so I decided against it. There are some really good products from a few companies that are just too expensive for my desire. I cannot justify buying esoteric level of components on a low dollar car like the X1/9 (no offense to the X, just being honest). So I've pretty much decided to go with the "14point7" unit: https://www.14point7.com/
    Unless I hear otherwise about their quality/reliability. But bear in mind that my O2 requirements may differ a little from yours. I need to use one that will tie into the aftermarket standalone ECU that I'll be using to manage the turbo package.

    Speaking of the ECU. For your build the stock FI should be fine, provided everything is in proper order. Adding a wideband O2 is a excellent idea. If you find the AFR is a tad lean, then there are some tricks to richen the stock system a little. However if it turns out that you are too lean then consider swapping the ECU for a aftermarket one. That will allow several significant improvements to the system with only a few other changes. And it will let you achieve any AFR's you need. Plus if you wanted then you could make more improvements and have a completely modern, fully capable system. I've worked out everything to run my FI with a standalone ECU and it isn't that difficult. The biggest expense is the ECU itself, but if you use a MegaSquirt product then it's not too ridiculous.

    Apology if you already said this, but is your bottom end all stock? These engines seem to have very robust lower components. I'd like to get turbo specific pistons but I'm not able to find any already made for these engines. Therefore I'd have to get them custom made. I've decided to retain the stock ones first and see what happens. For one thing I am only going low boost, and I have incorporated lots of things designed to reduce temperatures. Second, the stock pistons are of a very similar design to ones intended for boost; they have a really thick top ring landing, thick head, shallow valve recesses, smooth flat tops, thick rings/grooves, and are rather beefy by today's standards. Pretty much exactly what a turbo piston is, except they are not forged and don't have the latest alloy compounds. But for a conservative setup and a safe tune they may be fine. I guess the biggest risk is me getting over zealous and try to up the boost too high. I'm freshening up the rest of the bottom end with the existing stock components.
  11. tonyism7

    tonyism7 Daily Driver

    New Jersey
    The valve seat/ port bowl asymmetry you guys are referencing might be intentional. Sometimes it can be helpful to offset the bowl to one side to promote flow and swirl. SteveC might have mentioned it in his Ultimate SOHC thread, but I can't remember. That may or may not what you guys are talking about. The last illustration is this pic kind of shows what I'm talking about.

  12. Dr.Jeff

    Dr.Jeff True Classic

    Sin City
    Good point Tony. I recall Steve discussing that concept in terms of the exhaust manifold's ports in relation to the head's ports. By offsetting (enlarging) the lower aspect of the manifold ports it helps increase the velocity of the gas flow where it is slowest. And it's possible that Fiat intentionally designed that into the valve seat placement. That could be something that might improve flow characteristics around the valve heads if designed properly.

    Although I could also see it's possible that they were just sloppy in the building of these heads - kind of goes along with similar work in other areas of the vehicle. Off the top of my head I don't recall if there was a specific pattern to the offset placement of the seats - such as all of them being asymmetrical in the same way. I'd assume that would be the case if the offset was intentional. But I do recall that it wasn't consistent between ports; some had a lot of offset while others had very little. It's possible that someone had altered them on my head previously. But it's also possible that it was totally random from the factory, in which case I can't see it being a intentional design feature.

    But it's certainly a interesting thought. I like the idea and would love to believe the Fiat engineers were that advanced back then. :)
    Last edited: Nov 16, 2019
    Tavalin likes this.
  13. beezee

    beezee True Classic

    Thanks for the tip! Using this technique I managed to recreate a section of the article to include the pictures and save it on my PC.

    tonyism7 likes this.

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