cwsttu

ok i have been searching for a while about bridgeporting a n/a and i have found that....

a full bridge is harsh for a street driven car, but a half bridge is ok if you can handle a slightly higher idle and the loudness

a full bridge puts you around the 280hp mark

now what im wanting to do is rebuild a engine with the best possible design for the n/a, im still confused as to what puts out the most power... im not worried about how long the engine will last because i am keeping my original motor that is stock ported and running perfect on the side in case the new engine blows.... so in other words i would like to know the best power output i can get out of the n/a but i dont want just a streetport.... im also not really interested how much torque i lose so could somebody inform me just a bit more than the searches did? thanks in advance

powrdby13B

If your going to port it yourself, I think the best idea is a massive streetport.
Plus drill straight through the 3/5 4/6th ports to make it a 4-port engine with two massive ports... if you know what i mean...

Infini IV

Search the engine building forum over on the other forum. You could only get the most out of a full-bridge by going with a better intake manifold. A half-bridge might work well, although I haven't heard or seen a 6port running hard enough to convince me it is an alternative...

cwsttu

well i hear of streetports only being abotu 220 to the wheels... is that with this setup? i want some big numbers for the n/a... what kind of numbers will each setup push?

vipers

iTrader: (8)

^^^ agreed.... but also doing a bridge port would work just as good!!! most people frown on bridge port daily drivers cause they dont like to idle and are not happy below like 5000 rpm! but if you dont care about any of that (i sure dont)... then bridge the crap out of it!!! that is the best port (except periphial...but we alll know that)

Falcoms

The massive street port you speak of is still very harsh for the street without a turbo. I say a subtle 1/2 bridge on the main port while gradually expanding size while moving upward (toward the 2ndairy) and a good size full bridge on the secondairy. This way the 2ndairy dosen't open until the time the primary usually opens on a stock port. Also, this will yield more power while retaining low rpm torque.

see my reasoning? This is what I am planning on for my engine when it comes time for a rebuild.

EDIT: Also, the "other forum" is nopistons.com. They have a very nice section on porting of all types, pictures and all. This helps you get in the mindset that you want to be in when figuring out where and how to port. I myself have never ported an engine, but I am gaining plenty of knowledge from just reading and seeing.

vipers

iTrader: (8)

ive seen street ports push 180 hp ...... bridge ports.. like 210 (i think)

Falcoms

^ For a steet driven vehicle where the car in question must pass emissions, this is a true statement. When in a racing-type situation, you can get pretty good numbers on a good bridge port (as said before, ~280hp at the flywheel)

OverDriven

Wow you can actually get 280 with a bridgeport? I'm thinking when my TII project is done, I'll start modding my 87 N/A. Its been stock since I got it 4 years ago. I'll probably go with a BP and maybe a 75 shot of nitrous. I really didn't even know those power levels were possible with an N/A, which is why I got a TII in the first place.

-Joe

Aaron Cake

iTrader: (1)

This is what I did. Not as harsh as a complete half bridge, but still opens much ealier then stock. Of course, this is not an NA application...



If you want to get crazier, you can machine new 5th and 6th port sleeves to maintain the operation of the ports with the addition of the bridge. My setup just leaves all the ports open all the time (no space for the actuators with the turbo in there).

vipers

iTrader: (8)

lol.....in cali, you do anything to the block, and its bye bye emissions! even mild streetports tend to not pass (on a rare occasion they do)...

vipers

iTrader: (8)

hey aaron..... how does she run w/ the bridge?? was there a loss in daily drivability w/ that size port??

Aaron Cake

iTrader: (1)

Engine is assembled, but not in the car yet. Probably next spring. I'm assuming that it will be a beast.

vipers

iTrader: (8)

^^^ oh, i have no doubt she will fly!! let me know how she runs.... im really up in the air on what to do w/ my next motor.. street or bridge

cwsttu

^^^ i like that arron did... what does a full bridge look like? is the reason that is called a half bridge is because you added one eyebrow instead of two?

d0 Luck

what's your point??

vipers

iTrader: (8)

uumm. i think a half bridge is when the hole is only cut open half as much as i could be! still only 1 hole cut.... but the size of the hole(bridge) determines whether its a full bridge or half!

vipers

iTrader: (8)

lol....really, there wasnt a point!! some people tend to care about emissions!! sure as **** not me!! i have ......my.....ways of passing emissions!!

drago86

half bridge is only one runner (either primary or secondary,.. but primary only is kinda dumb) bridge, it has nothing to do with the size of the bridge,.. even though generally most people cut small half bridges because they are worried about engine reliability and half bridges usually find there way into street cars and not race cars.

rotarygod

iTrader: (1)

That's probably the single worst thing you can do. There are so many reasons why that doesn't work very well that it isn't even funny. I've written on it before. I have to keep saying it over and over again to this forum. Bigger is not always better!!!

cwsttu

ok so how would you build the best n/a.... what irons housings would you use and what port... i read on the other forum and some people say a bridgeport is not as bad as some say it is.... whos telling the truth?!?! lol good grief

rotarygod

iTrader: (1)

I'm only referring to hogging the outer housing ports out into 1 large port. Very bad idea.

Me personally, and I know others will disagree, for the nicest streetable motor (which is also subject to debate), I would use T-II 4 port housings with the 89-91 n/a rotors. I'd do a nice streetport or maybe even a halfbridge on the wild side. Long primary exhaust that collects near the back of the car. Duals are fine for stock to mild streetports but once you hit a bridge, you'd better collect it. Once again this is an example of how no one way of doing things is the best for every different situation. I'd use a nice intake manifold such as a Weber style throttlebody/manifold with a standalone ecu. That would all be pretty simple and still be fairly quick and not hard to drive. that's jsut how I personally would do it. There are other ways of course. You go to Australia and those guys think peripheral ports are streetable!

drago86

I disagree, mazdatrix's race car is ported like this, and it has been tested by others with good results.

Also i dont know why you guys think a streetport wont pass emissions,..icemark proved that one,.. pretty much as long as the idle isnt lumpy enough to tip the smog guy off, the cats and air pump will clean it up,.. im going to be smogging my aux bridge motor in a week or so,..

also, a bridge port in race trim can make 290+ rwhp,..

http://ausrotary.dntinternet.com/for...ght=ipra+300hp

drago86

If you really want the most NA power go PP,.. you can make 350+ HP if set up right,.. it will be fiesty on the street though,.. but so will a big full bridge. I reccomend you set a maximum RPM (which will be based off of how much $$ you have to buy high rpm goodies) and then figure out the porting from there going much over 9k gets expencive real fast,.. also consider how much tempermental problems such as part throttle bucking and such you can put up with on the street,.. this is differnent for everyone.

rotarygod

iTrader: (1)

Mazdatrix has this on a RACE CAR not a street car. He has also stated that at 10,000 rpm he still hasn't hit the horsepower peak and that there isn't much power below about 7000 rpm. How can anyone consider that a good thing to do for a street car? that is even less streetable than a peripheral port engine. Bigger is not always better and this is a perfet example of how.