Landon303

iTrader: (25)

Hey, have a few questions for the more experienced

I'm building a bridge from S5 6 port plates. No notching of the housing. Aux ports left alone, existing port street ported but only up (advancement in timing untouched as the bridge is doing all that; didn't bring the port down any)

Easiest way is to just show my series of pics, and have ya'll decide. Will I be OK w/ 2pc seals (will be using atkins, RA classic corner shown for ref). Or should I start over w/ another center iron?

Don't mind the lapping compound















Thank you!

fidelity101

iTrader: (11)

do not use atkins apex seals, they fit terrible in the OEM corner seals and pretty poor in the apex seal groove, maybe some bad combination of the two.

Landon303

iTrader: (25)

Oh ok! Thanks. The low price is appealing haha.

can you recommend another seal? Is the 2pc look like it'd be OK?

j9fd3s

iTrader: (3)

the QC with the OE seals seems to be better.

i am not the one to ask really, but it does look like there is enough support for the triangle piece

fidelity101

iTrader: (11)

A good builder friend of mine had a discussion about this relatively recently and it boiled down effectiveness vs price.

Ideally the steel apex seals are good until 8500-9000rpm. Above that you want carbon or ceramic (which are 1 piece seals) A good Bridgeport might as well be a full Bridgeport and to utilize the power you got to spin it fast so it means balance and clearance the rotating then use a light weight non metal 1 piece seal.

All of this = $$$$$$ and you haven't gotten into the proper intake/exhaust manifolds and injection style/tuning etc yet either.

In summary, its expensive "to do it right"

j9fd3s

iTrader: (3)

i suppose that is the real question with the bridge port, are you going for max power at the highest rpm, or are you trying to make it work within the limits of the stock parts?*

either way is ok, as long as you didn't expect the limited engine to make a zillion hp.

if you were making an engine that was rpm limited, it would probably be good to keep the intake closing less radical than an unlimited.


*apex seals, stat gears and the clutch are the biggies

Landon303

iTrader: (25)

Ah, fair enough. And that makes sense with the LOW price of the atkins seal.

All that said- here's the background on engine and it's "end goal"

I'm building for a friend, it's my first BP, 3rd time porting, and 7th rebuild. I'm not totally new, but I'm not an expert by any means. He's using full S4 NA rotating assembly, and knows that it needs balancing/clearancing for the high revs, but can't afford it. I've told him I will port and put it together since he's dead-set on the bridge, but NOT to take it outside the factory RPM limits. So that all said, we're not expecting much out of it power wise, just something with more than stock power.

Hate to be the center of a half-*** rebuild, but it is what it is I guess, as it's not my engine and I am getting paid on what HE wants haha.

Fidelity-- knowing this can you suggest what seals we ought to go with!

Thanks guys for the responses haha-- really helps!

peejay

I use Atkins 2pc on a full bridge port, no problems. Current engine has something like 38k on it, I forget, car's been parked for a few months.

I tried the 1/3rd bridge engine, it sucked, made the same power as a stock port. About 160hp.

j9fd3s

iTrader: (3)

if the rotors and weights are a factory set, and everything is ok, 8500rpm is no problem.

besides 8500rpm is the limit of the clutch

peejay

It makes me less than thrilled to hear that, given the number of times my 10k tach has pegged while on course.





BTW - Clearanced S4 rotating assembly. Clearanced with an angle grinder while the rotors were chucked in a brake lathe. No rebalancing...

Landon303

iTrader: (25)

Wow the 8500 fact is good to know. I'm gonna casually NOT tell the customer that just so there's less chance of it blowing, though. hahaha.

Peejay ha!!! Duuuude I love it!!! I may have to clearance some here that way. Did you do tips, face or both? Sorry about your 10K mishaps :P

peejay

Sides of the tips. Previous engine with these rotors saw 10k once by accident, had a couple shiny spots on the sides near the corner seals. Not all three (twelve?), just one here or there I hit them with the angle grinder until each face was .002 smaller (.004 total) and I'll see how it is if/when I get to pull the engine apart. I did some oiling mods, mainly heavy porting of the inlet and outlet to the oil pump on the front side housing and teardropping of the passages on the eccentric shaft. Porting only begins with the intake and exhaust ports, the oil system can and should be ported too. I cut the filter open after every oil change to verify that the bearings aren't digesting themselves and so far so good.

My experience with 1/3rd-bridge was less than heartening. I kept that engine to an 8k limit because I was using 3mm iron seals (all stock GSL-SE everything) but that was fine since it didn't make power that high anyway. The engine I have now has a Holley manifold. Much more betterful.

Rotary Powah

iTrader: (1)

Good thread, I'm planning on going the exact same porting route on my S3 6 port - Primaries and secondaries bridged, aux ports left alone, using OEM Mazda 3mm 2 piece seals. With a 50 DCO to top it off. Good to see some people aren't afraid to bridge a 6 port

peejay

Mostly it's the people who have not done it yet

j9fd3s

iTrader: (3)

turns out i was wrong, the RB stuff is good to 10,500….

soOOoooo with non hardened gears and stock bearings, i think 8500 is still good, and if it sees 9000, or even 9500 once in a while that should be fine.

i actually had a friend with a big bridge, all factory rotating bits, no balancing, and he ran it to 11k all the time, and it would see 12k here and there. he ran a 750 holley, on an RB intake, exhaust was a road race type header, into 2x2.5" pipes, it did 231rwhp@9600, which is where the dyne stops reading. it was also his DD, and did 26mpg down to seven stock.

sometime this year, i'm putting together the biggest bridge i've ever seen, it makes the giant bridge in the HTMYrx7 book look teeny. i feel that the engine is going to be angry, and it may make less power because its too big...

jjwalker

Late to the party...

Firstly.

Looks good to me, you actually have more "bridge" than most housings I see. The key here is to think about where that spring sits on the corner seal. The blocked edge on the inside where the spring seats. As long as there is a good spring there, it should stay in place. I would only be worried about long term mileage (it's a bridge port so I doubt you give 2 ***** about reliability into the 200k mile range). Nature of the beast is that apex seals springs tend to sag and clatter at very high mileage and I could imagine that that might cause it to catch the bridge and yank the corner seal out.

Secondly, what happened to all your cars dude? I have been looking for your thread and never saw what the outcome was.

Landon303

iTrader: (25)

Looks like the motor will be going together here SOON! Probably the next week or so. Wound up going w/ atkins seals (dude's budget was kinda tight -___-) but they're new seals, so yea.

I cut a rotor w/ an angle grinder to get a visual of where the seal's path of action would be, and man, i feel MUCH more confidant now. In the pics above, I have the seal perpendicular to the housing. Well, it's actually at an angle, so there's even more of the corner piece supported than I'd originally thought. Which is a good thing.

The one last thing I have a concern over, is the aux ports, and the lack of "ramp" in them. I know all about JB welding/devcon/whatever epoxy'ing a ramp in the end, but it still seems risky. I'd hate for it to drop into the engine. I may just leave it as-is. I'll have a search around & see what others have done.

jj- Oh yea! I stopped updating that thread to let it "die" as I figured that may be the safest solution. But here was the outcome-

we wound up (week or 2 later) finding out it was EVERY neighbor on the street who was complaining. Not sure which one actually started the code enforcement call though, but regardless. We put up a 6' privacy fence that masks any and everything to do w/ a mazda RX-7 other than the 2 up front my wife and I daily. It looks like a "normal" house now. It's been about 7 months, and I haven't heard a thing. Well, I have heard this from the ONE neighbor that talked to us about it (how I learned everyone had a problem was through him too)- He told us HE hasn't heard anything either, and prior to that, he heard ALLLLL about it. So I think it's safe to say we're in the clear. Thanks for checking up on that!

j9fd3s

iTrader: (3)

it does pay to be nice to your neighbors!

with the atkins seals, you may want to take some extra time and make sure they fit everywhere, seems like the trouble spot is in the corner seals. i wouldn't anticipate any problems, but its better to check for no reason than it is to toss it together and have it not work

Landon303

iTrader: (25)

Yea def! We've been really kind & never retaliated, for fear of the worse, haha.

Ahh good catch. Will do. In the event it's too tight, is that something I may be able to correct on... maybe a granite block & some emery paper?