I actually just went by Brian's (BDC's) house today to drop off mufflers for another forum member and we talked about bridgeports, among other things. What he told me is basically what slammed said. He (way back) used to not see the point until a friend talked him into doing a small half bridge and he immediately notice an earlier spool of the turbo, and it didn't drop off high up. Hes definately sold me on a half bridge whenever I can finally afford a turbo car. He also sold me on Atkins seals, but thats a different story...

 

spooling a turbo up is all about velocity. i don't see how a half bridge helps that... but i am intrigued. we usually give the exhaust ports a little earlier opening and a more direct flow out the port to help spool the turbo's up. didn't think a panty line over the secondary intake port would help with spool. it definitely didn't on my buddies car full boost @ 5k on a 57 trim... not even a 60-1 but like i said that turbo sucked and his new one will show the true value.

i honestly may just do a half bridge anyways just to fully see if it's worth it or not. i'm not a big fan of the brap brap idle tho :/ hahaha

and again, i do apologize if you think i'm bashing. i'm not trying to, i praise bdc for his work. he's a great guy and very smart with rotaries. i'm just not sold on the half-bridge yet, but i want to be hahaha. i'm just being stubborn i guess. i'm running twin t04's on my TII so spool isn't really the issue. it's full power and i know that i can make my goal on a street port. but if a half bridge will truly allow me to make my goal at a significantly lower boost ratio or so then i will be sold.

hmmm... i dunno... i'm a little drunk at the moment hahahahah SORRY!

 

I am shooting for around 400 rwhp. I want to be able to do this without pushing the limits of the motor for greater dependability. The same idea is going to be carried over to the turbo that I will use on this project.

So, what would be a fitting turbo for this? I am looking to run a Haltek E6K on it as well. I am trying to get all of the parts needed to start my project by early next year. ie...turbo, ems, injectors, ignition, and fuel supply system. Any input on these other matters would be greatly appreciated.

Thanks

 

Properly done bridgeports are not a problem. You run into issues when the eyebrow is cut into the side seal path (catches the leading edge) or when the bridge is too thin and cracks. Following any of the vendors templates eliminates making the eyebrow too large but it's your discretion to keep the bridge thick.

Most porting does not effect reliability unless you are talking about seal-eating streetports (BIG ports that cut into the seal paths) or j-bridges.

A half-bridge bridges the secondary ports (those on the rear and front iron) only. A full bridge also bridges the primary ports (on the intermediate iron). To confuse things further, with 6 port engines you can do an aux bridge which only bridges the auxiliary (5th and 6th) ports.

Easily done with stock ports. Or if you want to deal with a little less turbo lag, a street port is more then adequate.

60-1 turbo, Haltech E6K, 720CC primary, 1000CC secondary, Walbro 255 LPH pump, front mount.

 

yep, that's dead on! the 60-1 will easily make your power requirements on pump gas and will spool up plenty fast.

 

so lets say if I got a bridgeport on a s5 FC NA, what kind of ECU would i need to make it run properly?

 

If 400 is all you want, you can do it on stockports. I did it, and so have others. No unreliable B-port necessary.

 

A standalone.
A bridgeport is probably overkill for an NA, though. It would have a pretty peaky powerband, not something well suited for street use. You can get 170+ to the wheels with a good streetport and some fuel control, and still have it very usable around the street.

 

wow, this is a great thread, some fantastic info here.

I think that the stock TII manifolds are restrictive personally, I can't think of what else would be making my topend suck. I gotta go check my intake manifold thread!

You need a standalone to make any bridgeport run properly. (or a carb)

 

I dont think the BPs unreliable at ALL. I drive mine everywhere even untuned with about 200 miles on tank. Just watch who does your cuts..they may cut too close.

But anywho, the BP spools the turbo quick because obviously the cut allows air to come straight in and straight out the exhaust ports. But i will say not everyone will need a BP.

 

How many miles have you logged on your BP?

 

I ran a t78 on my streetport FD for a short time, right before I knew I was going to rebuild and HBP (different irons). I got spool around 4300 with a little power dropoff after 7800.

WIth all else in the setup left the same except the porting I immediately saw faster and stronger pull from the turbo, spool by 36-3700, and stronger pull on the top end.

I've never heard anything bad from people who actually ran a HBP, other than the extra noise and slightly high idle. Everyone loves the driveability and power output.

 

ummm whatever a years worth of driving does..so around 7k for me.

 

Okay,

Everyone knows they dont last a long time, but with everything else in the rotary world, there have been MAJOR advances. Please dont think I am trying to call you out. Just let me know when you exceed 10-12000.

 

It will run on the stock ECU, but fairly crapily. You really need a standalone that gives you complete timing and fuel control (timing control around idle and light throttle is key).

If you are bridgeporting an NA, you are probably going for max power. So don't bother with a half bridge. Go full bridge or go home. Both will have basically the same low end and light throttle issues, as well as the idle...

But especially with the S5, you have to look at something other then the stock NA intake. Either swap on the TII intake, use something like the individual throttle bodies or make something custom. I bet the VDI doesn't like bridgeports one bit.

The stock TII manifold is fine. Many people have made plenty of power on them, with good top end. I'd look elsewhere for any problems (a dyno graph really helps here).

You'll never get a bridgeport running "properly" with a carb. Half bridges especailly because of the major difference in flow between the primary and secondary ports (generally the carb manifolds run the primary ports of the primary venturies, then the secondary off the secondary venturies).

I know a bunch of people with half bridges. A few of them are daily drivers with 50K or more (kilometers) on the engine...

 

I was thinking a 2 barrel actually :P

but I wonder if the low vacuum at idle would cause major issues with a carb, I think it would.

I daily drive my halfbridge now that it runs right! :P

 

How big is your exhaust housing on that turbo?

 

I am talking fullbridge.. and for reference, 50k is 30k miles.

 

I'd like to hear more about this auxilary bridge (and no, I ain't talking Star Trek, neither ). It sounds kind of interesting. You might be able to increase the top end without affecting the low end (for a S5 n/a with standalone).

30k miles, is 50k km in real units.

 

There should be no question of the reliability, like i said it depends who cuts them and how..for instance you do an extremely wide cut I would think twice. my cuts are not that. Nor do they question the reliability of the irons holding but, PM BDC, he has done several 8hr trips on his bp.

 

 

I know brian, thanks..

The question is, what is a reliable amount of mileage you can expect from a fullbridge?

I say 10k or so.. If its more, then GREAT! That means the Bridge is coming up well! Just give me concrete examples!

Please believe me when I say I am NOT trying to instigate some form of flame war. Just some good solid evidence that the full port is starting to outlast its "reputation" if it were..

 

I am sure that you know brian, I know brian myself, he lives 2 minutes from me. lucky me. Also I know that you are not trying to get things stirred up. I guess if you lived by us and lived and breathed BPs 24/7, you'd be just as sold. I honestly think I've got more than 7k on my BP, As I come to think of it we did it back in Jan 04'. Bought a Jspec tore it down and went straight to town on it. So...Over two years of driving everywhere in it, Im sure that is more an 10k.

 

to bring the point up again since i'm not the only one who wants to know:
aux bridges on a 6 port motor?
this is a setup i'm thinking of in my head . . .
true duals
electronic aux ports
true cold air or ram air intake
possibly a custom designed plenum
and the BP aux ports only
running on standalone


wouldnt that be sexy?

bolt a cat in for emissions day and other than that its fun time!

 

oh ok, i see why it's a little more reliable...... cause there's barely an eyebrow there! i call that a panty port

nah i'm just messin. looks good... i'm still debating. i may just give it a shot. if i don't like it or it doesn't work out i can just build another one.