porting on the head intake side.

[pj91gsx]

I have ported the exhaust side of my head, but i was wondering if it is a good idea to port out the area where the head runs up to the valve guides. Would it be a good idea to port more on the intake side for a bigger turbo, like a holset and would it be a good idea for a 16g. I assume it would be a bad idea to port the intake for an all motor right?

 

[delta448]

I'm not an expert on porting as I've said before, but I'll share what I do know since nobody else has replied yet.

Porting the intake side is more involved and technical than the exhaust side on a turbo engine's head.

On the exhaust side, really all you care about is removing all resistance to flow, the ideal shape is a cone that starts at the valve size and ends at the port matched size. The intake side is more difficult since you are concerned with increasing overall airflow and removing flow restrictions, but are constrained to keeping (or modifying slightly) the taper so as to retain air velocity and proper cylinder filling. One trick often used is machine work to accept larger valves. Then the passage has some guaranteed room for improvement.

An intake passage with between 1.7-2.5 percent taper per inch (or roughly 1-1.5 degrees of angular taper) has been proven many times over to produce the best results. Example: If you have a x-sec area of 2 square inches behind the valve seat, the x-sec area 1 inch from the valve should be between 2.034-2.05 square inches, 2 inches from the valve it should be 2.068-2.10 square inches... and so on. This is a very basic idea of the concept usually applied to some more technical intake manifold runner designs used for determining the runner's ideal taper. But intake manis have other variables to consider such as tuned runner length and optimal overall volume.

I know enough to know that I don't know enough to give you advice on what to do on your own at home as far as porting the intake passages of your head and actually gaining some performance. I would suggest checking with some proven porting experts like FFWD to see what they can do for you.

 

[pj91gsx]

when porting I do best when I just go with the flow on the exhaust side. I ported the exhaust side pretty well, I just am not so sure on the intake because i think it will take longer for the turbo to spool if too much is ported. am I right?

 

[delta448]

Not really. The turbo should not be affected, just the airflow through the head which is the important thing anyways. If airflow is increased, you will increase torque regardless of what it seems like the turbo is doing.

You can't really cause the spool of the turbo to suffer by just porting the intake side of the head. The turbo sees the same or maybe more exhaust flow from porting done anywhere, but the compressor side will produce the same amount of air when the turbine is spinning at any given set speed. What is affected is how well the head conveys that air to the cylinders.

Making head intake passages larger increases the volume the turbo has to fill before pressure rises, but at the small changes in volume that porting gives you and the relatively large volume of air flowing through the head, you're talking about only a few microseconds difference even at very low boost on even a smaller turbo. Same principle as increasing the diameter of your intercooler piping. Large volume of air flowing per time versus a relatively speaking small change in overall volume to be filled.

The shaping of the head passages are very much more important than just increasing the size of the passages. The goal is to remove restriction and smooth out the pathway to be as straight as possible. The final bottleneck in porting is always the valve size and camshaft profile.

I guarantee that you won't feel any major differences as far as spool-up is concerned if you do a good job. You may however, feel the increase in power.

But, if you do a halfassed job porting, or don't really know what you're doing, you can actually hurt airflow and make mid/upper range rpm transient spool quicker -all while lowering engine performance and moving in the compressor map a little towards the surge line. Again, let me stress that the shape is the important thing here, not necessarily the size alone.

 

[pj91gsx]

makes sense. so regartless of the turbo I should run big or small the head should still be ported the same correct?

 

[delta448]

Not necessarily. If you want all topend for an all-out dragstrip power curve you can make compromises to shape that increases flow only in the rpms that count, but increase them significantly more than typical street porting.

Usually when porting is done this happens a little anyways. Excessive or not enough taper, larger cross sections and the air velocity gets decreased. -Which may increase the max flow of the head, but decreases cylinder fill at lower rpms because there is less momentum of the air mass to pull in more air during the scavenging and before the exhaust valve closes. That can be offset though with different turbo and cam choices. The camshaft selected really has to work with the port job to get the most benefit from head porting.

 

[pj91gsx]

Im not really looking to run cams, because I want to make my car fuel efficient as well as performance. Would porting the more than cleaning it up be worse since I am not getting cams? I just want to keep the option open as using it as a daily driver with a ported 16g or a drag car with a holset. If I threw the holset on would it not be worth it if I didnt have cams?

 

[delta448]

Porting is almost always a good thing if it's done correctly.
Head porting to me is an art form. If I were you, I'd do a little more research on techniques used by some of the pros or I'd keep the changes pretty mild at first. Gasket match the port, maybe thin out the wall a little between the two valves, keep it simple and it's less likely to be detrimental. Leave the heavy modifying to the pros with high tech equipment.

 

[BrokenTsi]

Personally, I wouldnt even touch the intake side at all. Unless you're trying to run 8's and you cant figure out how to get any faster, I wouldnt even bother porting at all. The stock head is good for just about anything as it sits.

 

[pj91gsx]

Personally, I wouldnt even touch the intake side at all. Unless you're trying to run 8's and you cant figure out how to get any faster, I wouldnt even bother porting at all. The stock head is good for just about anything as it sits.

its too late now, but I think Im doing a great job. I know how to do the exhaust side. the intake I just took out the imperfections and left it with a sanded finish for the fuel and air to mix. I have 4 4g63t heads and I have ported the exhaust on 3 of them. I just port match the gaskets on the intake and exhaust.

 

[Bestwestranger]

If you're going for fuel efficiency and not full on racing power, don't touch the intake side. With its stock size you'll get higher air velocity, and with its rough casting surface, you'll get more turbulance which will help mix the air/fuel. Both are good for torque, and torque is good for economy.

The last time I had my head off to replace the gasket, I ported the intake side (exhaust, manifold, and o2 housing were done the time before that) and my butt dyno recorded no appreciable difference in power/spoolup/etc.

There is alot of good info on the web concerning the breathing aspects concerning n/a and boosted engines. Read up on both types and you'll learn alot, and don't get all your info from one source. What it basically comes down to is that if you want low rpm power (torque), don't port at all or do it in small amounts. If you want to build a race engine (big hp), want bragging rights or just like shifting at 8k all the time, port everything you can get your hands on.

But there's also people like myself that spend 90% of their time tooling around town but ported everything anyway, just to gain a little time and experience with the procedure. And what the hell, those parts were just sitting around anyway, right?

 

[Mr Peepers]

I personally wouldn't change the shape of the port at all, just remove the casting flaws(blending). Gasket match the intake side(and intake mani while you're at it) but not the exhaust side; there's NO reason to hog out the exit of the exhaust port just to neck back down in the runners. Maybe knife-edge the wall between the valves a little but I don't recommend doing more than that without a flow bench and a lot of (educated) experience.

 

[pj91gsx]

Thats good information. I am planning on assembling and finishing porting this Saturday. I finished the intake side in terms of cleaning it up, so I will just leave it. I did way more porting on the exhaust than Mr. peepers is saying I should have done. I'm confident in my work and I have been working on this head for at least 6 months, just looking for information on porting the head and doing the work. I will post pictures if I get the chance. If I ported the intake a lot would it make a noticeable difference of worse gas mileage?

 

[Bestwestranger]

If I ported the intake a lot would it make a noticeable difference of worse gas mileage?

Theoreticaly it would because you'd be shifting the powerband a tad higher, but I doubt you'd take immediate notice of it. You'd probably have to put pen to paper and do some mpg calc's to see it.

Like Mr Peepes said, a good gasket match and a little knife edging would be your best bet. I probably wouldn't even mess with the intake manifold. All the ones I've seen so far match up really well with the gaskets...

 

[dsm-onster]

Just to add to the above. . .

Im not really looking to run cams, because I want to make my car fuel efficient as well as performance. Would porting the more than cleaning it up be worse since I am not getting cams? I just want to keep the option open as using it as a daily driver with a ported 16g or a drag car with a holset. If I threw the holset on would it not be worth it if I didnt have cams?

Fuel economy doesn't waste away with a cam upgrade a many state. THEY drive it differently. This is why fuel economy dwindles. A cam that provides higher VE (any cam upgrade) also leads to less pumping loss and thus better brake specific fuel consumption if you're careful not to play too much with your newfound power. Better BSFC directly affects how much fuel is needed for a certain load and thus gas mileage. I see 33+ mpg with my fp2X cams when I want to.

Nevertheless, the holset (in a bolton housing) will spool almost as fast as the 16g and flow way more. Definately worth it, since your powerband width won't change, but your overall power will . The hx35 is as streetable as the evo3 16g in a bolton housing. Once you swap to it, you probably won't bother going back to the 16g for daily driving.

 

[pj91gsx]

would the holset, be pointless if I didnt get cams? Would it make sense to install it if I wouldnt push a lot a boost daily driving it, but install it for when I want the power as well. I dont think mine is the hx35. its from a 2003, Ill find a way to make it work though. is the size of the hx35 different in size from the newer years. this turbo came from a dodge cummins turbo diesel.

I also have access to a flow bench so I will be able to do a good port job with the use of the flow bench.

 

[dsm-onster]

I believe all 2003-2004.5 are hy35s. There is no bolton housing. The hy35 comes with a non-divided turbine housing. T3 flanged so any ebay t3 manifold will work very well.

An hx35 is not pointless on the street. It spools super fast in the bep housing. Why would you swap back to a 16g for running on the street when it spools about the same? Just turn the boost down. Wht do you want for the street fast spool and decent power at lower boost for pumpgas.

An hy35 should spool faster than an hx35. The hx35 in their twin scroll housing with a true divided manifold spools increadibly quick. The hy35 was installed on the automatic cummins trucks up to 2003 for the neccesary faster spool (like the stock automatic 1g is equipped with the 13g). Everyone now is only speculating how fast an hx35 spools in it's stock turbine housing where a true divided runner manifold is used. But it's likely faster than an open scroll BEP housing. The hy35 has a smaller turbine wheel and was specifically installed on the cummins to spool faster than the hx35. . . So like I mentioned previously, you may never want to swap back to a 16g for the street because it's likely it just won't matter at street boost levels. And, it will likely flow at the same boost yielding more street power at the same boost with no knock. When it's track time raise the boost. Then drive away at lower boost and 16g spool speed.

 

[pj91gsx]

here is a picture of my turbo. should I consider porting the holset on the t3 side, it definitely could be port matched. should the stock waste gate be fine as well? wouldn't the t3 exhaust manifolds from ebay crack? I was considering on welding a t3 flange on my stock exhaust housing and porting it heavily on the flange side. Then I was planing on making a bracket or two to support the weight on the turbo to take stress off of the manifold. what do you think?

 

[dsm-onster]

We're way off topic . Just PM me with any other questions about the turbo. I might be able to help you.

It's definately an hy35, as the center cartridge is affixed to the turbine housing by a v-clamp.

The stock wastegate is known to be way too tight for under 30 psi. It may be the actuator or it may be the hole is too small. Or a little of both. Get an old garrett t3 wastegate actuator and place holes in the actator flange for a fit. These actuators have threaded arms that can be lengthened out to reach the holset wastegate flapper. You'll have adjustable actuator pressure, too.

The turbine housing MAY bump the block with an adapter bolted to the stock manifold outlet location. You'll just have to find out.

Port matching throughout the exhaust preturbo is VERY important. From what I've actually seen of the hy35 the turbine inlet bolt pattern is t3, but the actual inlet is a bit more rounded at the corners. Port matching the dsm flanged manifold with the garrett adapter is going to be more time consuming. And when done is still going to be quite less than ideal.

I'm really excited that I met someone with an actual plan to run the hy35 on their TEL! Many other 4cylinder platforms show good results (turboford, turbo volvo, honda, 240sx). Super fast spool and very thorough topend. A little more choked than the hx35 because of the smaller turbine wheel. But should do very well for a 400whp goal for sure. They go for a bit cheaper than the hx35 because most upgrade to the hx35 from the hy35 for marginal gains in flow.

 

[pj91gsx]

so I would need an external wastegate. right? I have a 1g intake manifold and a 1g cyclone. which would be better for the holset? or should I get a better intake manifold?

 

[dsm-onster]

Try the cyclone and the 1g. Nothing beats field testing . Of course a SMIM would be better. But the 1g intake manifold isn't terrible. My holset h1c doesn't mind my stock 1g intake manifold. It doesn't drop off up top at all. Yet, I have a cam upgrade as well.

I recommend an external gate. This would give you an opportunity to do up an adapter that would transition better from MHI to garrett. Something like the below but with an MHI flange instead of that Toyota flange:

 

[pj91gsx]

ok cool. Im just going to start pm-ing now. I missed that before.

 

[Freerevving]

I also recommend an even, gradual taper from port to valve... It's a lot quicker than exhaust work, and a lot of metal is removed in the process... but when it come to how much you remove, less is definitely more.... 1G INTAKE PORTS ARE ENORMOUS
Almost parallel to the valve stem (a little further toward the valve seat), a little more can be removed... just imagine the air flow... the air path needs to bubble out slightly near restrictions... I just make the pocket a little deeper

edit... don't forget to mildly smooth the short side radius