rx7anator

ok i got my engine all apart and i cant see myself spending $100 on some metal with outlines so i can port my engine.

so...at my sho we do a lot of deisgn work and i can sketch up the stock port. then inlarge it with any offset and print it out on this clear plastic .

so my question is...when you port. do you make the whole port larger by the same amount.

or do some parts get inlarged and some dont as much.

if its decently easy to get the right port shape...i WILL sale these...for ALOT cheaper then racingbeat.

Thanks

Brad

Jeff20B

iTrader: (13)

You usually go up and also smooth the inside to remove any casting flash.

rx7anator

say im gona do a street port...is there a certain shape im looking for..or just a bigger stock port.

and with the exhaust. should i just make it larger and circle-er. to closer match the outer port.?

Thanks

Brad

purple82

Here's the thing with porting. The shapes of the ports are tuned for the desired engine performance. They are altered to increase duration and "lift". It's pretty easy to screw it up and get a crappy running engine.

Racing Beat, and anyone else reputable, has gone through alot of plates tuning the engines in. That's why their templates are so expensive, you're paying for the development, not the flat sheet of aluminum. You'd be damn lucky to hit a good design on the first try without any past experience.

rx7anator

well that pretty much shut me down...lol. i COMPLETELY understand that companys go through and lot of r&d...but i always like to try and do things my self if i can. that and im VERY cheap(as are we all) ...and broke most of the time.

maybe i can buy a street ported housing and exhaust ported housing off ebay and copy the design.???

diabolical1

iTrader: (3)

this is NOT as easy as it sounds, but it's just to help since you say you're good with designs. as long as you have a good mental picture of what the rotors are doing in the stages of their travel you should be okay.

just rotate a rotor on a shaft over one of the side housings and measure where the side, corner and oil seals travel, then use a marker or something to get a good port tracing, then make your own template. for the exhaust, start going wider first, then, move up or down depending on where you want overlap. then do the same with the marker and make a template.

Rx7carl

Buy or borrow templates from a reliable source like RB or Judge Ito. Porting is much more complex than it looks. Your altering the characteristics of the engine and its easy to ruin what was a good engine. Dont **** around. The real skinny on this subject is over on nopistons. Theres enough material and pictures to study in the engine building and porting section by Jugde Ito (porting expert) to help you. GO READ THE WHOLE THING, you will not be disappointed.

Rx7carl

Actually what I contemplated and peejay posted once is to dykem the side housing, then drop a fully loaded rotor on an eshaft on it. Spin a couple of times and you have the limits of the seal travels for reference.

rx7anator

i actually have read that whole thing. when this site was being upgraded and i had nothing else to do.

oh yeah i took my motor into the shop today to clean it up with the ozzy juice and let our head desinger, mastermind, car guy take a look at it. he actually new basically what was going out...but through out the day EVERY guy in the shop asked me what size cam i was puttin in it.

and one guy thought the exhaust ports for where the dizzy went.

oh well.

any one wanna give up some 12a street port templates for free or cheap??? (free being the key word)

capri93

OK here's a sugestion theres always people looking to buy templates my self included. Get a set of RB temps. copy them and sell them cheaper make your money back. If your copy quality is good I'd buy a set.

Rx7carl

You are missing an important point. The templates are (for the intake) fitted to the iron plates using the dowel pin holes as a set point. If your off by any reasonable margin (like say .002") you can be in for some real trouble.

capri93

Didn't think it was quite that precise.

Rx7carl

Well, the bigger you go, the tighter the tolerances cause your getting closer to dropping a seal into the port. Go read what Ito has written over on nopistons. Get the flavor of whats going on, then make your decision. I would personally only get one from a reputable source, or brew my own. Its not worth the possiblity to me of ruining a multi thousand dollar engine cause I was too cheap to get good templates. My $0.02.

purple82

Not to mention the questionable ethics of copying and making profit off the work of someone else at the other person's expense.

diabolical1

iTrader: (3)

couldn't have stated it any better.