Since this is copied from the housings Ken races with now, the port timing is already proven.
If it was up to me to come up with it we would be pretty screwed. Well actually I would have had more homework to do.
These are going to be resurfaced after they are flushed so I can be a little more aggressive while I am flushing the tubes.
But if the housings were not being resurfaced it would not be any different than any other porting. You ALWAYS have one hand as a tool rest and the other working the tool. You go slow and you will get the feel pretty quickly. The main thing is learning control and being patient. The aluminum will cut much quicker than the steel insert of the rotor housing. You have to keep that in mind when you are transitioning between the two.

 

Scalliwag,
How would you like to do me a big favor and take this measurement for me?
THANKS!

(see picture in next post)

 

-

 

Since I am copying this from Ken's pports I would have to get his okay to give something that specific. Otherwise he may be a little upset if I post it on the net like that.

 

Well if you could ask him his permission for you to tell me (and if you want to tell me) that would be great!
How about if I keep it confidential and don't tell anyone or post it on the web at all?

 

I don't mind asking him and since this porting is *supposedly* the same as a factory pport (something I have not physically verified though) He probably realizes that makes it in effect a measurement that could be found elsewhere. I will be talking to him by the weekend.
I am going to be doing a set for David Sanchez. He won the first NHRA-Import all-motor class in 2000 but his brother passed away and he dropped out of racing. He is starting to get back into it. He made me swear on my life that I don't even let anyone except myself and the spray shop even see his housings. We are going to be resurfacing his side plates as well and he gets jittery just talking about letting them out of his sight.
David has put together a lot of motors and did the trial and error to get to where he is now.
I can understand his reservations since I am extremely secretive about how I mill and polish housings since it has cost a shitload to get to this point for me too.

 

Just by looking at the housings I could tell you the port timing and dimensions but out of respect I won't. What I can tell you is that it's not the same as factory MFR housings. The MFR ones are very conservetive. They measure 46 to 47mm ID and I'm going to leave it at that! The good thing about the MFR ones is that they can be ported to whatever dimensions you require. If only they were much cheaper.
I'm also in agreement with Ken about the port design. The angled ones like the Racing Beat type are not as good as the ones with the straight port entry angles.

crispeed
87 Rx-7 TII
9.204@150.47mph
2600lbs
un-tubbed

 

If you know or already have measurements feel free to post them unless they were given in confidence to you by someone. As long as I am not giving out the information without consent is all that matters to me.
So post any measurements you wish.

 

Yeah, I think I know the port timing from looking at those pictures as well. I just wanted to get as much info as I could you know

I have also heard that straight-entry ports are better than the ones angled upwards, but I don't have any experience to know for myself.

 

The RB style in effect points downward and with the face of the rotor coming up towards it I always figured it had to have a negative effective on the flow.
The more the angle is pointed into the direction the rotor is turning the less turbulent the reaction would be.

 

Yeah, I know what you mean. I was meaning the exterior of the port upwards, and the interior of it downwards if that makes sence... same way you are describing.

I agree... sounds like basic physics principles to me.

 

Right. In a forced air setup it would not have as much negative effect, but an NA would sure feel it. Granted there is a "pulling" effect as the rotors are spinning, but I am not sure just how much it helps.

 

Do you plan on using the rubber hose connections or welding on some studs or something to bolt the intake to?

Does that interfere with any dowl pins?

 

Oh I forgot to ask, is this going to be an NA or a Turbo engine? (I'll go prepare a new change of underwear now in case you say turbo)

If it were me doing it, I would weld on some 3/8" flanges onto the pipes to bolt the intake too.

 

Ken runs in the All Motor class so these "particular" housings will be NA. He has two 55mm TVI throttle bodies and 4 big honking *** injectors. He uses hose instead of flanges. I have an idea using o-rings in grooves and set screws. But that is for later on. It will look a lot cleaner than either flanges or hose.

 

How is this project going? Got any new pics ?

 

No new pics. I got the holes bored for the tubes in the housings Ken gave me. I have not got my bullnose live center in from Harbor Freight yet Of course with the 3 day weekend I could REALLY use it right now. I tried cutting the tube the same way I cut the first tube and it was a dismal failure. I was not able to get it to center very well and by the time I had cut it tru it was just a little too small. That really sucked and looking back on it I could have avoided ruining the tube. Chalk it up to a rookie mistake.
But I have the hole boring down to a science My jig absolutely rocks. If I bothered to find a deeper holesaw would be the only thing that would make it better. The holesaw bottoms out and you have to back it out and pop the outer "plug" out and then you can drill the rest of the way.

Here is something I should point out that can really get you in trouble. Look at these two pictures and note two things. In the first picture you may notice this was a non-turbo housing. Look at where the drill enters the housing through the water port. This port is blocked on a non turbo and gives a good flat surface for the bit to start cutting.
On a turbo this is not blocked so the first surface you hit is at an angle. For those of you who don't know what this means; starting a drill at an angle is TROUBLE. The bit will try to walk and no telling where your hole will end up.
Now this is where the machinists start laughing because with the *right* tools this would not be an issue. But where there is a will there is a way.
What I did for turbo housings (and now I use it for all) is made a drill jig out of a piece of 3/4" X 2" aluminum stock. It is about 12" long. It bolts to the exhaust studs and has a 1/4" hole where the bit goes into. Using a 6" long 1/4" drillbit I go though the hole on the drill jig.
You still have to start the drilling off slow because it can walk if you try to rush it in too quickly.
But the drill jig does help for two things. 1) It makes it easy to setup because it makes it obvious to where to drill the hole. Believe me when I say that makes a lot of difference. 2) It helps to keep the bit from walking.
I will take pictures of the drill jig if anyone is serious about doing this. Also be sure to drill the holes for the exhaust studs very tight. ANY play would be a VERY bad thing. You want it to not have any play at all.
Once you drill the 1/4" pilot hole you will remove the drill jig (just in case someone does not see this as obvious)
So scroll back in forth between what I wrote and the pictures to be sure you fully understand what I am talking about.
If it is confusing let me know and I will take a series of pics to explain it better.

 

Thanks for the tips. I know exactly what you mean by how the bit would slide and not grip into the right point if the surface was angled like on the TII housings.

If you want to take pics of your jig that would be nice as well

 

Okay, we will just knock the whole thing out while we are doing it. I am sure someone will ask for the full monte Plus I can give more detail since there are pictures to refer to.

1) In the first picture let's make sure everyone knows what the housing looks like.



2) This is what the drill jig looks like. There are two jigs being used. One I referred to early on in the thread is the jig the housing sits on while it is on the lathe. It sets the height to where the 1/4" hole in the drill jig is level with the bit. The housing jig also adjust the angle so you can square the housing 90 off of the drillbit.



3) This is what it looks like mounted on the housing. I use nuts on the studs. This was just for picture purposes.



4) Two things to note in this picture. 1) There is a "ledge" where the arrow points. You either need to make the drill jig short not overlap it or grind a clearance so it does not sit on it. 2) Note how tight the hole is around the stud. (ooh, dirty talk!)
Hopefully this will help some of you take the leap. Plus you can make a couple of bucks off people that lack the ***** to try it. After all, one set will pay for the equipment Let me know if you do because you owe me!

 

Okay, a PM indicated that by mentioning the two different jigs (drill and rotor) that a description of it would be helpful.
So here are pics and descriptions. There are a lot of ways to accomplish a jig and a lot will depend on your lathe. This works very well for me and makes bores in the exact position over and over.

1) This shows the way it sits on the lathe. See previous pictures on page one for reference to what a housing looks like sitting on it if neccesary.



2) Since the jig comes on and off the lathe it is important that it is easy to make sure it is aligned correctly. I put a stop plate on the jig so that when I put it on the lathe I butt the stop plate firmly against the table before tightening it down.



3) To control the angle of the housing and to lock the jig there is a 1/2" socket head bolt that is accessed through the hole (see pic) The plate has been drilled and tapped for the 1/2" socket head bolt. I used a 1/2" thread because it needs to have the hell torqued out of it so the rectagular tube does not pivot.



4) I cut about an inch off of two dowel pins. Get short bolts that thread into the end of the pins. using a drillbit close to 12mm drill the holes for the pins with a drillpress being careful that they are straight. Then drill just the top holes oversize for the pins to fit. Put the pins in and bolt them down.

 

WOW! Thanks!!! I don't know what to say right now...

 

The size of the dowel pins are 16mm the last time I check which was today while I was dowelling a 12A for a friend!

crispeed
87 Rx-7 TII
9.204@150.47mph
2600lbs
un-tubbed

 

it is worth it to really dowel a motor or only when your running huge numbers like 500+ and stuff?

 

There is a huge debate over if it's necessary or not.
Most AUS/NZ rotary builders will swear upon it.
Most NA/PR rotary builders don't do it.
I'm not sure what that tells you though...

I know some rotary shops have given gurantees on their modified engines they sell to people that if they break from twisting they will replace it for free.

There doesn't seem to be a downside to dowling though (other than the price) so it could be good for a precautionary measure. Or is there a downside I just don't know about?

I've never dowelled a motor before... I've never made the power on a motor to require dowelling (yet)

 

I'm smelling another project!