I removed the sleeve, torched out the diffuser, build up a weld on the edge that faces into the rotor housing and then ground it down to meet flush. It makes for a really smooth transition. Yes the divits that the roll pins came out of are going to be filled back in and ground smooth.

So for all those who say "you need turbo housings to port the exhaust"
enjoy

 

Are you going to fill in the top two holes? Looks good.

 

Hadn't thought about it, probably should when I take the sleeve out to fill the roll pin divits.

Thanks

 

loking Great man

 

Your "streetport" looks as big as my exhaust port on my 12a bridgeport. Does that mean your port is big, or does it mean my port is too small? Here's a pic of my 12abp ports. Your port looks nice BTW.

 

Finally someone that knows how to port an exhaust! Great work. Looks really good. It's got the proper rounded bottom and flatter top. This gives the best flow. A flat opening with a rounded top is terrible for flow and it has nothing to do with total open area. You're going to have a really nice motor.

 

those housings look ******* mint dude!

 

Thanks for the support, this engine is actually my first time porting anything other than a 5hp briggs on my mini bike back in the day.

I thought the port was a bit HUGE myself, but RB calls it a street port.
https://www.rx7club.com/rotary-car-performance-77/turbo-na-housing-difference-476862/
I've heard exhaust should be 70% of intake area. I should be somewhere in there. It's only gotta push a 2000# car (VW beetle) so a little less low end is not exactly going to break my heart.

Funny you shold mention the housing condition...
I went out on a limb on the advice of my dad. This is usually a catastrphic idea but he is a mold maker of over 40 years and knows a thing or two.
he took one look at my housings and said what about the lines? (light chatter and just wear stuff) I said its fine, just gonna be a little less than perfect.
He busts out a box of hone stones basicly and says this should do it.
So I basically "honed" my housings. It took very little material off and took for ever.
I probably have 8 hrs of manual honing in my two housings. I went from 220-400-600 grit then down to a polishing stone. It was very hard to develop a consistant motion but after an hour or two I could work a nice cross hatch and keep the stone very flat to the housing. Bottom line it was worth it!

I'm worried about my trans, right now it's just stock VW IRS (not swing axle) I am planning a rebuild but I still have to figure out how much power this thing might make and what it will take to keep the trans from grenading.

 

dang it all my pics from honing are too big to uplaoad... ill work on that

 

www.rxbeetle.com (site in progress)
Huge pics there of some of my handy work

 

Difference is his is a 13B and yours are 12A housings huge difference in the size of the ports.

 

That DOES look like a very nice port.

The only thing I did different (besides smaller for my turbo application) was I squared out the upper corners so I could put more radius in to the "runner".

Check out yawpower.com In Paul Yaw's flowbench info he goes through porting an exhaust port cut by cut with flow results. You will see that you might want to square out the top of the port more!

That is going to be an awsome motor in that little car. Do you have Fred Puhn's book "how to make your car handle"? In that he covers the VW swing axle suspension as it was used a lot in grass roots racing for its simplicity. Basically, run stiff springs for little movement and also run a "Z" bar accross the rear axles so they resist raising together under braking. As for all the power through the transaxle.... A bus unit or a built box $$$ ??

 

I have a super beetle, no swing axle here. Full double CV jointed half shafts and McPherson struts up front. (chew on that nader!) I have a rear sway bar tucked in there and The front is getting lowered about 2" with stiffer springs as well (they are actually rear springs from a Honda CRX on adjustable perches)
The bus box is really pricey and from what I am reading guys are running down into the 10s with built type 1 transaxles. It becomes a question of components and build tollerance. for instance 3rd and 4th gear are only pressed onto the output shaft of the stock type 1 trans :O

I read the Yaw article, tons of good info there. I might try and square the top radii a bit. My next step is surface grinding my irons and re-nitriding them. Should be good as new.

I've seen numbers in the 160 and as high as 200hp on a NA street port engine. Any idea where I should be sitting with this kind of porting, megasquirt, and exhaust similar to this: http://www.rxbeetle.com/index.php?fu...e=P1010062.JPG
I am basically going to make a new header identical to my 12A but out of SS and with the 13B flange.

 

I know it'll be wider due to the housings being wider, but his port timing looks more aggressive as well. It looks like it opens sooner than my port, and stays open longer than my port (closes later).

 

Remember that while Paul's exhaust ports may have been more squared up top, he also didn't have any exhaust sleeves installed. I'd leave those alone. They look great.

 

Ah,Super Beetle! Sorry, I had missed the part where you had mentioned you had IRS.

This is going to be an awsome car. I remember reading the BFG G-force challenge where a stock class? Super Beetle battled it out in competition with cars such as 3rd gen RX-7 and WRX on skidpad, slalom and track times.

I was impressed by the #s of the Super Beetle- if it would have had some power like yours will...

One of my dream cars, seriously. I want a bug, mini, and Fiat 500 in my garage with my rx-7 and Honda N600.

 

Everyone should own a beetle once in thier life and should drive it through one winter. I drove mine through two and it was more than engouh.

rotarygod: Good point, I am a bit slim on wall thickness in the top of the sleeve.

 

Exhaust port sleeves. This should give you a clear idea of how I got em out and built em up. I did end up filing the holes in the sleeve.

https://www.rx7club.com/attachment.p...&stc=1&thumb=1
https://www.rx7club.com/attachment.p...&stc=1&thumb=1

 

RxBeetle~
That looks like some pretty sweet port-work you've done so far. I love it. I'm especially impressed with your removing the splitter and how smooth everything looks. I can't wait to see the motor in action. I will definitely be tagging this thread for when I start working on the streetports for my '87 13B.

Doc Holiday~
I have a picture request on your engine. I'm in the process of building a streetport 12A and I just finished the rough cuts on my exhaust this past weekend. I did a somewhat custom job on them, basically, I bought the RB race templates and then made them a little shorter and wider. They sort of look like yours now, but I'd like to see any closer shots of yours if I can. I'll put a link to my thread here in a few minutes and hopefully the new pics of mine will be posted by the weekend.

Thanks, and kudos go out to both of you guys.

1

 

Mine don't look as smooth because I opted not remove the sleeve and have materials welded to smooth it out, but it should get the job done.

Some links:

12A exhaust port questions

My 12A streetport buildup

 

looks great diabolical1! Is this going to be carbed? Nikki or aftermarket? If you need any parts let me know, I have a half blown 81 12A that I will need to get rid of when this baby goes in.

I did most of the finishing with a couple different sanding drums. Final polishing was done with a felt drum and polishing compund. I was at the abrasives store this week and I could have kicked myself for not getting there before porting. Oh well, next time.

What is really getting to me is that I can't push this engine to it's limits due to the fact that I do not have a vehicle capable of handeling the power without investing some serious money. I have all the machines to properly pripherial port the motor, and a turbo would be just make a good thing better. But how the hell am I supposed to put 500+HP through a vehicle that was origionaly designed to handle 1/10 of that... For now I'll stick with a nice NA and gain the experience for the next one, hehehe.

 

Sorry bud, thats the best picture of the exhaust ports I have. I have some pics looking from the outside, but I dont think that would help much. I'll attatch them anyway, mayeb it'll help.

 

thanks.
i'm always looking for 12A stuff. so if you have that engine into the early part of 2006, i just may take you up on that. hell if you'll part with the whole thing, i'll come buy it off of you then. i'll keep you in mind. i plan to follow this thread for as long as you are building.

 

man, anything is better than nothing ... which is pretty much what i had before now. thanks.

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Some pics of the intake ports as per Mazdatrix template and my handy work.