ninj4

What gains can you get from porting and polishing this generation? I dont want to spend a lot because it will just be a daily car until i can afford an fc so i was thinking of just a port and polish to give it a little extra oomph.

Alex-7

A port job on any seven requires an engine tear down so unless you do it your self it will not be worth your while, esspecially if you don't do headers + exhaust at the same time.


If your not going to keep the car for very long you should just try and find a used header or buy a pace setter header for it . That'll ad a little extra oomph without breaking the bank.....




--Alex

ninj4

Thanks bro.

vipernicus42

iTrader: (4)

Best way to get power out of a 1st gen Daily Driver is to get an exhaust. RacingBeat exhaust is the way to go, +20% horsepower, seriously!

You can also get Rx7Carl to rebuild your carb, good power/cost ratio

Jon

leif

you can also take off your intake manifold and match the smaller holed on the manifold to the larger ones on the engine...then pollish the inside of the manifold while you have it off.

Jeff20B

iTrader: (13)

I thought port matching it will screw stuff up. Ask Carl.

Rx7carl

I wouldnt reccomend that. You can gasket match the secondaries at the engine interface and grind out all the bumps that you see looking down into the top of the manifold. Beyond that, porting the intake manifold gets tricky.

BMS2004

also heard that jeff, something to do with "reversion" do a search on port matching that might show some light.

Jeff20B

iTrader: (13)

Yes, the carb spacer holes are also machined to reduce reversion.

Edit: We rotorheads often do not use the word 'polish' when we talk about porting because it's such a boinger word.

Jeff20B

iTrader: (13)

Carl speaking of grinding out all the bumps that you can see looking at the top of ther manifold, is it a good idea to try to smooth the dual plenum at all? The way the channels are cut has very sharp edges. Can they be smoothed at all without killing power? Also, can the runners themselves be port matched to the gasket?

leif

carl...why is matching the ports such a problem...??? my friend and i made a template from an old gasket...and then expanded the ports on the intake to match those on the engine...

i assumed this would give more power and better responce.

we practiced on a few junked mannifolds first to see how far we could get with out breaking into the water jacket...is this the tricky part you were talking about?

gerbraldy

I want your FB's, give them to me.. you can have my vert..

Rx7carl

Yes, rounding that cut for the plenum (horizontal) is a good move. Also try round the floor of the plenum so its not so sharp. You can gasket match port the secs, but not the primaries. The loss of velocity kills the low end. Now if its on something thats more demanding like a BP or monster port, that might be a different story.

Rx7carl

It wont take much to break into the jacket on the primaries (which I assume you have found out by now). The problem is that opening the primaries runner exits absolutely kills the velocity which in turn kills the low end power of the car. And you dont feel much on the top end so IMHO its a losing mod. Try it with one of the manifolds youve already cut into. Nothin to lose right?


PS- I didnt actually edit your previous post. I hit edit instead of quote. sorry bout that.

Jeff20B

iTrader: (13)

Thanks for the info. The engine only has street ports. The manifold has already been somewhat port matched up top, but the ports where it bolts to the engine are still stock. I'll see how this manifold compares to the older seperate runner manifolds I have, to see how different the primary port size areas are.

leif

hum...interesting...i will have to see about this...we undertook it after a friend
(the one who gave me the design for the manifold) told us about the performance gains he had with one of his race cars.

but i havent atcually tried the part yet...so now im curious.

85MarkRx7

I port matched all the ports and the plenum and I gained alot of low end power I can take off in first without giving it any gas and I and go from first to on up through the gears without touching the gas oh btw I idle at 750-800 rpm.
Weird huh

Jeff20B

iTrader: (13)

That's pretty cool. I only hope my so called port matched manifold wasn't done incorrectly. I'll have to dig it out and take a picture and let Carl judge it.

Hyper4mance2k

iTrader: (40)

Yea Pics on porting would be awesome. I picked up an extra manifold so I could port it, and Now I hear all this bad sutff about porting and I'm all iffy about it...

italian_stud02

i port matched my primaries, not a whole lot of anything. i think it evened out due to the porting of the seconds at the mid range. my car was a sludge bucket with that port, and i didnt get wild with it either.

leif

i wonder then if the gasins came from porting the plenum...and not the manifold...luckily my plenum was ported and rounded...