Porting Intake manifold

[KTM-EXC]

I already searched for this topic which answered alot of my questions, but I still have a few more questions.

 

I just started porting the runners on my intake manifold, I also started porting were it meets the throttle body for my new 60mm TB. Im using an air die grinder. To get the rough shape so far I have been using a carbide that I got from work. Im not sure if Im using the right kind because every other minute it gets clogged, which makes sense seeing as its aluminum. Is there a specific carbide I should be using for aluminum?

 

Also.. Once I have cut out the rough shape with the carbide is it alright to use griding stones to finish it off? I have dozens of them at work in all different shapes that I could use. I remember reading a long time ago in some type of hotrod magazine that when it came to intake ports you dont want to have a smooth glass finsish but you want it a little rough, this was on a carbed V8 so Im not sure if this applies?

 

THank you for your help in advance,

Rob

[veritech-z]

Leaving the rough finish on the runners with a carburator has to do with helping the fuel stay atomized from the carb to the intake ports of your cylinder head. This isn't so much of an issue with an injected manifold, since the manifold only flows air, but would be important on your actual intake ports on your head. I'd say doing the mirror finish on the intake manifold runners wouldn't hurt-just don't know how much it would help either.

[KTM-EXC]

cool, thanks

[Clifton]

You need to keep it lubed. WD40, Liquid Wrench, ect work good. Spray the arear every few minutes. Also non ferrous burs don't clog as easy and remove material alot faster.

[BRAAP]

First off, your choice of using Carbide for your cutters is a GOOD one. Carbide lasts MUCH longer than high speed steel, carbide also allows for a faster cutting speed. Sure, the initial cost for carbide is a little more, but if you do much carving at all, in the long run, Carbide cutters end up costing less than half that of high sped steel cutters and carbide allows you to work faster which also saves time. In short, if you are at all serious about carving or porting, think “carbide” only.

 

For carving on aluminum theses cutters ARE different than what is used for carving on iron. The gap of the flutes, the included angle of the cutting edge itself etc. When shopping for cutters for carving on Aluminum, they are generally referred to as cutters for “Non Ferrous” materials. These cutters will carve pretty much any material as the name implies, (which implies SOFT non ferrous metals such as brass, aluminum, magnesium, etc. Non magnetic stainless does NOT fall into this category). In short, you need cutters for “non ferrous” metals. They are a little better at “self cleaning” and will also cut with much more authority. If you use these “non ferrous” cutting bits on ferrous metals, they will dull rapidly.

Also, cutter tip speed is critical in regards to cutter life and clogging. In “the machinist hand book”, there is a formula for calculating this, but for our DIY projects, typically, a carbide cutter spinning at 20,000 RPM and hogging aggressively on the soft Datsun heads and intake manifolds will cause the cutters to clog. The slower the cutter spins, the less it will clog. A quality die grinder that allows for variable speed is the E-ticket. Other wise, you can get an air valve to attach inline with the air inlet of your die grinder and you can regulate the air flow that way, (in the picture linked below of my die grinders and cutters, my “hog” die grinder has this adjustable restrictor on the air inlet). Also, there is wax available that porters use while porting for extending periods. Just dip your cutter into the wax periodically. This helps keeps the cutter cool so the aluminum wont get stuck in-between the flutes so often and also helps to extend tool life. Another “bubba” trick is to have a nice soft piece of cast iron laying around, say an old Chevy iron block that has little to no nickel in it. When the cutter starts to clog, just run the cutter firmly against the cast iron and that will purge the cutter of the stuck aluminum. This will shorten the cutters life, but is quite effective.

 

In this thread is a picture I posted of several cutting bits for ferrous and non ferrous bits approx 2/3 the way down the first page.

 

http://forums.hybridz.org/showthread.php?t=110269

 

 

Hope this helps…

[OlderThanMe]

AH! So the master shows his tools!

I have a couple carbide bits but unfortunately they are for ferous metals. Time to pull out the Rutland Tool catalog and order some!

[BRAAP]

OOpps. I forget to answer the rest of your questions…

 

For final finishing, do NOT use stones. Never uses stones on aluminum and never grind aluminum on a grinding wheel. The stones/grinding wheel can and will explode if grinding/carving aluminum. Aluminum clogs the stones like you are experiencing with your cutters, but when stones/grinding wheels clog with aluminum and then gets really hot due to continued use,(Aluminum expands when it gets hot), it causes the bonding agents within the stone to come loose and at the speeds the stones/grinding wheels spin at, it literally grenades and the end result is usually a trip to the ER. Not good. Sanding wraps as pictured in the link I mentioned above is what you should use.

 

As for how far to take the finish inside the runners themselves… I take it this is an EFI intake manifold, and as such, this is what is called a DRY manifold, i.e. there is no fuel flowing through it, just air. Dry intakes can be mirror finish smooth. A totally polished finish requires LOTS of time and there is a place in this polishing process that we all deem the point of diminishing returns. This point of diminishing returns varies on the individuals patience and available time. With a fine sanding wrap finish inside of your intake manifold on even a hot street engine, you’d be hard pressed to get a measurable increase in HP on the dyno if you spent the time to completely polish it, though if it were completely polished, that would be ideal scenario for a dry intake, as I mentioned, it is debatable whether it is worth the time and energy.

 

As for the intake ports in the head, these are essentially “wet” at approx. half way down and as such, HP gains by leaving a little texture vs a totally polished surface is one of those “6-one, half dozen the other”, propositions. For race “only”, and if you have the time, polished is what you should strive for as the throttle will be at WOT most of the time so the port velocity will be high any way. For street applications where part throttle response should be considered, at least, somewhat important, traditional wisdom dictates that an “as cast” or similar finish in the port would be ideal. But once again, on the dyno, you’d be hard pressed to measure a gain that is substantial enough to warrant the effort put forth.

 

My personal opinion on the DIY port finish… There are MANY other areas of the engine build and tune that would benefit from that kind of effort and attention which could yield much greater gains… But then again, you can never pay too much attention to “ALL” of the details when building your engine. The more attention to detail you pay, the bigger your rewards…

 

 

Hope this helps…

[Sam280Z]

A cheaper and readily available wax for the cutter wax Paul refers too, is toilet seal rings. They are about a buck a piece and available at every hardware store. I've never used it on a carbide cutter, but it works great on the sandpaper wraps.

[KTM-EXC]

Wow.. thanks for the help

 

Paul. What exactly should I be using to for finishing, sanding wrap? If so what grit? I really apreciate the help. Its a good thing I didnt work on porting that tonight or I would have pretty much done the opposite of everything you just said. Ill be taking a trip to the hardware store tomorrow.

[mrparks]

Pardon me if I'm wrong, but even if that area is ported out, wouldn't the runners still be a restriction?

[zeiss150]

Let me just say ... Paul, dude

 

Also, I ported my TB opening for the 60mm, and I finnished it with a file and it turned out really smooth... I know that has nothing to do with the runners but..... there it is.

 

P.S. does any one know if they will ever have an episode of "overhaul'n" with a 240, 260, or 280Z? just wondering cause I would love to see what Foose would do with a Z!?