black79

I decided I might as well try porting my engine today, before i start putting it back together. I have never tried this before and i would like to know what you guys think of it. I would apprectiate any constructive criticism (how ever thats spelled) any of you have.

chino_rx3

iTrader: (3)

Well I think you still need to polish it more inside, need t make sure no groves or

lines .need to be smooth so gas and air will just go right in with no problem every

little drop maters, too many lines , smooth it out.

Stanis

iTrader: (2)

How close to the oil control ring path did you get? The 3rd picture looks like you did fine, but the 4th one looks like you may have ported in that direction. Run a clean t-shirt across the port and rub the edges of the port. Does the shirt catch or snag?

black79

Yea I ran a rag through the passage and it didn't snag or catch on anything, I'm pretty sure that I didn't go too deep into anything, I didn't really take to much material out, as I think this is a pretty mild street port. I was using small sanding drums on the end of a dremel to try to smooth it out, is there something else I can use that would polish it up a little better? What do you guys use?

Jeezus

iTrader: (4)

Are you using the major port of the bridge template?

EDIT: What I am asking is are you not going to be porting the eyebrow, just the main?

black79

yes, thats all I'm porting, I'm not cutting out the actual bridge itself. My brother-in-law just had the bridge template from when he ported his so I decided just to use that one.

Jeezus

iTrader: (4)

Cool cool. What I heard is that the streetport is a bigger port than the main port of a bridge. Point being the Bridge, you have to leave room for the corner seal to glide over, whereas the streetport you can cut as much as 40% into the corner seal travel area. Just what I have heard... I know it is not good to spread "he said she heard" stuff, but if someone could correct me if I am wrong (or who has a same dealer made SP and BP template) that would help

Nice job on the porting. I just got done grinding out some PP housings.

black79

So are you saying that I didn't make the port big enough? I know that a street port is such a vague term so maybe this is not enough to make a differance? Thanks for the compliment on the porting. Did you try to polish yours out at all? If so what did you use?

'84-12A-GSL

Use the two different grits on the sanding drum, than buy a couple different grits of fine grit paper and get in there with your fingers if you really want it to shine. Than hit it with a buffing when on the dremel. But I wouldn't polish the intake ports to a shine. I'd leave some texture for better air fuel atomization. Unless you're running FI. The exhaust on the other hand, polish to a shine.

bugman1973

id cut the bridge in it if it were me or cut the ports just a tad bit bigger. im planning on running a odd port configuration when i do my rebuild

Hyper4mance2k

iTrader: (40)

They shoud look like this: http://bdc.cyberosity.com/v/EnginePo...1b3322b91b77d6
but those are good for your first attempt.

black79

Bugman 1973, why would you suggest that I cut the bridge out? Do you think that only using the main port would be too small? Do any of you think that there is any negatives to having the bridge port?
Hyper4mance2k are those pics yours? If so what did you use to polish them like that?

djessence

There are always negatives with a bridgeport. No low end, relatively low engine longevity. Just so you know.

dantheman

iTrader: (4)

Use cartridge rolls and flapwheels to get that finish. I would finish everything off with a 80grit sandpaper. I try to make sure that a fingernail does not hang in in any scratches that I see.

black79

so what everyone is saying is that by just using the main part of this template that the porting would be too small?
I know that with a search there is a lot of topics about engine longevity with a bridge port, but I am wondering if anyone could tell me if they have had any experience with an engine that quit pre-maturely that was actually caused because it was bridge ported?

black79

anyone?

djessence

Well people are saying its too small but it is still porting nonetheless. You are making the port bigger. Maybe not as big as a bridge or large street, But there will be some difference. Will it be huge difference, probably not but it will change a bit

Jeezus

iTrader: (4)

Porting is fine. Just that the bridgeport does not port as "high" up as a streetport template will. The bridge of the bridgeplate supports the corner seal, and the streetport can actually go up a little more into the corner seal ares.

Please excuse my horrible MSPaint drawing. 30 seconds, literally.



Red = bridge
Blue = street

I would get some templates for both ports, but I do not really feel like spending $90ish to be like "Hm, they were right/wrong"

black79

Ok thanks for the drawing. I didn't realize that the bridge-port wasen't as high as a street-port. This car will not be a daily driver, but it also won't be a track car. I need to know just how bad a bridge-port is to drive in traffic, as well as if anyone has had major problems because of the bridge-port.

'84-12A-GSL

what did you use to do the porting? A Dremel? With what bits?

djessence

it sucks in traffic, no low end power/torque at all. Its a race port basically. So they want all the power at mugh higher rpm, as well i believe it allows greater rpm range so you have more top end as well. All of these factors reduce longevity because you have to drive the **** out of it. Its just a logic thingand the stress formula, maybe not as extreme on rotaries but with pistons (omg i did not just mention that word here) 2x RPM = 8x stress on engine.

So if you have nothing below say 4000 RPM, you are going to spend far more time between 4 and 8 constantly not going up and down through the range. This causes stress, stress = engine failure. For a hard driven bridgeport, the engine life seems to hover around 40-50k (miles i think). Not great considering most of us get 160k from factory built engine before needing a rebuild.

black79

Yes I used a dremel with a few different shaped carbide bits. These bits work very well, and seem to last forever. These were the same bits that were used to port about 3 other engines by my brother-in-law, and they are still very very sharp. I'm still kind of up in the air about what I should do with the porting. By the way if anyone was wondering this is an S5 Turbo motor. Also, I am am going to be running the stock turbo for a while, will this have any effect on which porting I decide to use?

rotpower

I had a bridge port as a daily driver for a couple of years way back and I can tell you exactly what it will feel like. Basically, you will not be able to go on a date in the car. The passenger will start asking you what the hell is a matter with your car as you are loping around in 30mph zones in 3rd gear. If she isn't a total gear head and an understanding daisy duke type lass that maybe has visions of stardome in the Dukes of Hazards, she will never understand why your car runs like it does putting around. It's hard to have smooth, natural conversations with someone as the car bucks at every brap, brap, brap, brap as you are breath on the throttle lightly at a civilian pace through neighborhoods. In fourth gear it will really buck around town. Yes, every video you have heard that has that infamous bridgeported brap, brap, brap sound at idle will be felt through your rump loafing at 30mph in top gear. There is a lot of overlap in the intake with a bridge port at idling speeds. And you are essentially idling at low neighborhood speeds. If you've driven a, hot, fast, two-stroke bike around at low speeds, picture that.

Having said that, your bridge port will run like a scalded dog at mid revs and full throttle and if your lass is understanding about this type of play, you (and her) will love it.

Additionally, a bridge port will not benefit fully without copious amounts of fuel, breathing through a mandrel bent, very free flowing exhaust. Build the exhaust right with a VERY unrestrictive muffler and you will throw 4-6 foot fireballs out the back of the car as you back off the throttle at 8,000 RPM setting up for a turn. It is simply a fabulous show at night. Sometimes the backfire can be deafening if you are on a tight two lane road that has a wall on each side. A great way to scare the sh*t out of your passenger if they are not expecting the bang. And IT IS A BANG!
Sounds like a gunshot.

In my opinion, if you bridgeport a car, you need to go for the whole enchilada. Fuel, exhaust, ignition, plugs, the works. Make it breath otherwise, you are wasting a lot and not benefiting much with the bridge and might as well live with a large street port.

My bridgeport was way back when Racing Beat was just getting noticed in the early 80's. I drove an RX-2 in high school that had a stripped interior, road race suspension, Holley 600, hardened gears, pinned rotors (good for 10-11,000 rpm) and the old square Racing Beat box muffler that basically had few baffles and that was it. At times I bolted on a megaphone after the Y past the rear axle and went down the back roads near my house. It ran like a rocket and there were only few cars that could hang. Built muscle cars with road race suspensions. There would be an occasional BMW 2002, or Datsun 510 that could hang in the turns, but never on the straight.

After a couple of years, I reverted back to the street port.

So, it is up to you and whether you want to live with a bucking car and value performance over normal every day comfort. To me, it didn't matter back then. I had one thing on the braing. Today, two decades later, if I built a bridgeport, it would be exclusively as a street play toy that I would only drive occasionally on a sunny day. Similar to owning a really fast bike. If you bridgeport it, do it right and bolt on all the goodies. Do the high rev mods and you will have a screaming dragon at 10,000rpm. The thing will really breath at 6000-10000

bugman1973

i was just saying cut the bridge out because it does look like you could go more in to the housing. thats a really small street port. doing it thats small to me just seems like you polished the ports but thats all in how you see it i guess. when i get mine done it will be a lot bigger than that but i have different plans than you do.

black79

well the car is only going to be a street play toy, and only driven occasionaly. As far asdates go, i'm pretty sure my wife won't let me go on any dates and i'm also pretty sure that she will never be in the car so I'm not too woried about that. I guess my biggest fear about the bridgeport is losing the bottom end. How bad is the bottom end power with a bridgeport? I mean does it feel like your driing a really slow car at low revs, or is it that it just dosen't pull as hard as it does at say 6000rpm? How much different will the acceleration be from a stock port to a bridgeport?