These were done last night. I spent about 4 hours alone total on the bridgeport cuts on an already done set of street ported front and rear irons. This is the same half-bridgeporting scheme I offer to folks who do T4-style setups and want more mid-range and high-end power that still want decent street drivability. The bridgeport width and length (heighth) is kept conservative while the same types of radius'ing and other modifications are made to help 'accent' its flow as an additional intake port as opposed to just having a cut made straight down into the iron.



http://bdc.cyberosity.com/pictures/S...alfBridgeport/ For all pictures



http://bdc.cyberosity.com/pictures/S...t/Spec-C_1.Jpg



http://bdc.cyberosity.com/pictures/S...t/Spec-C_4.Jpg



http://bdc.cyberosity.com/pictures/S...t/Spec-C_6.Jpg



http://bdc.cyberosity.com/pictures/S...t/Spec-C_7.Jpg



http://bdc.cyberosity.com/pictures/S...t/Spec-C_9.Jpg



http://bdc.cyberosity.com/pictures/S.../Spec-C_11.Jpg



B

damn .. thats nice .. when its time for a rebuild, i'll keep u in mind.



J

looks good



must have killed you to nick it on the bridge though https://www.nopistons.com/forums/pub...#>/biggrin.png

I just tried posting on this but the server whacked out. My apologies for a repost.



Anyways, yeah I was pretty pissed off when that happened. It happened at the tail-end of finishing the second eyebrow cut. I think I was edging up the port closing timing on the eyebrow when I did it. My lower back was killing for about 20 or so minutes from being hunched over for hours working on it whilst standing the whole day so it had something to do with it. The housing is getting lapped after this is all done so it won't be an issue; still noticable in the pictures, though. https://www.nopistons.com/forums/pub...1047683664.gif



B

yeah even if it doesnt matter it's still one of those things that makes you want to strangle someone.

Oh YES. I definitely felt like that after it happened. I was furious because I'd spent several hours that afternoon and evening working on those, flawlessly, only to have that happen with about 5 minutes left to completion. https://www.nopistons.com/forums/pub...1047683358.gif



B

https://www.nopistons.com/forums/pub...IR#>/bigok.gif very nice looking thanks for the pics

My projects always get fucked in the last 5 min if they get fucked at all.



NIce job Brian.. Pix look great.

Typically how long will the bridge hold up?

Thanks, man.



Yeah, that always gets me when it happens. It's difficult to avoid sometimes when you've got an 1/8" grinding stone whirring at over 25,000+rpm; it wants to grab on to anything and skip around.



How long will that kind of bridge last? I'm not honestly sure but I wouldn't bet it'd die any sooner than your average stock or street port. That bridgeport is quite conservative -> the bridge itself is still quite thick and wide. I'll measure the thickness of it tomorrow and tell you but I believe it's about 0.225" wide or so, or right at 1/4". It's fairly meaty compared to those uber-thin on es that you may've seen crack.



B

looks real good BDC. what are shape of bits that you use for that?

I use 1/8" grinding stones for it; cylindrical-shaped or cone-shaped. Nothing fancy really; just something long enough to clean up and edge the eyebrow cut in all of its depth.



B

Thank you Justin https://www.nopistons.com/forums/pub...IR#>/smile.png I really enjoy doing this kind of work. It's very satisfying.



B

Don't forget to mention Mineral Ice for the lower back https://www.nopistons.com/forums/pub...#>/biggrin.png https://www.nopistons.com/forums/pub...#>/biggrin.png https://www.nopistons.com/forums/pub...#>/biggrin.png

Somehow, I get the feeling that you know exactly what I'm talking about, Ito. https://www.nopistons.com/forums/pub...DIR#>/wink.png



B

looks great as usual brian.



Roan

Don't suppose it passes emissions? https://www.nopistons.com/forums/pub...#>/biggrin.png

Overlap doen't look too bad... I suppose its possible, no? The secondary runners shouldn't be getting much, if any, airflow at low load and idle conditions anyway...

I graduated from mineral Ice to Percocit and Trnasdermal Fentanyl for the back pain :(

I seriously doubt it does. I suppose it's worth a try but I doubt it. https://www.nopistons.com/forums/pub...IR#>/dunno.gif



B

It might. The overlap from the bridge might have no effect. Since you'll be running on primary injectors only and possibly with the secondary throttle blades closed.



Fuel would have to come in the primary ports, out into the bridged secondary ports, then re-enter the combustion chamber when the bridge and exhaust are open together.



I say try it!

I think its possible. The secondary runners receive little to no air under light throttle since the secondary butterflies are closed, so the secondary runner porting should have limited effect on emissions.

I guess I'm the only one who thinks they are a waste of time then?



What I've always wondered is these BP's are not back-cut correctly, and they do very little to added flow.



I think you got dyno graphs of another BP motor running, and it clearly shows that the BP does very little to add to the power.







-Ted

I've seen dynos of 2 cars built by the same builder with the same turbo, etc. Only difference is street port vs half bridge.



One made 425 hp @ 15 psi, the other made 463 hp @ 15 psi.



They work. Whether you can do the same thing with a more aggressive street port may be possible.



I believe you already had this argument. Let's not start it again here.

I originally thought it was a waste of time myself, Ted. I was originally against the idea until a friend of mine all but cornered me into doing this on his engine a long time ago. Even with lousy bridgeport cuts then, it turned out to be very effective. At first blush, they may not appear to work to you, but trust me they do. I honestly wouldn't go through the trouble and the hours involved in punching these things out if they weren't beneficial in some way.



B

maybe if you disconnected the secondary throttle plates so they stay closed? i'd be amazed if it could be done https://www.nopistons.com/forums/pub...#>/biggrin.png , we have a visual too

Oh, I didn't say it wasn't going to do anything.

Maybe I should reword it to state that if the BP was done "properly", it would've made a whole lot more power.



Not start it here? Are you afraid one of your gurus is perhaps wrong?

I'm surprised no one has said anything this long, since I know there are competent BP porters out there that'll laugh at the BP that BDC is cutting.



Maybe I should just use pictures...



This is what I'm talking about - BDC uses no backcutting on his BP's.

http://fc3spro.com/TECH/PORT/bp2.jpg



The backcutting profile is one of the most important points for (any) porting. If you're ignoring this fact, you're got a lot to learn about porting in general.



If BDC would kindly post one of his dynos off his BP motors, you'll see the little "tail" in the dyno graph at the tail end of the run. That's his BP's effectiveness on the power band. If you've ever seen a turbo'd BP, the dyno graph is significantly different - it basically just shoots up with no sign of dropping off on the top end.



If you guys want the truth, you need to be able to comprehend what I'm saying. If you want to stay in your own little world, then I'll just shut up right now.





-Ted

See previous reply...



Your BP's are basically only effective if the main port gets overloaded. Your BP then takes over any "overflow" that can't efficiently flow through the main port. I had my suspicions on your ports initially, but I couldn't prove anything; your dyno sheet confirm my suspicions[sp?]. You should try and compare your dyno runs on your BP's with other turbo BP's. There is a big significance in the curve. Other BP's have a flat, climbing torque line, while yours do not. You can easily analyze your curve to confirm my suspicions that your BP does not flow until way up in the RPM band.



Without the backcutting, there is no easy path for the intake charge to go through. Through fluid dynamics, we know that the air intake charge will tend to flow straight and hit the wall of the main port before taking a bend into the combustion chamber. Look at the BP port pic I just posted - you can see the how much easier the intake charge can flow to get into the combustion chamber. With the nil backcutting if your BP's, there is no easy way for the intake charge to get through the BP unless the main port is overloaded.





-Ted

Do you have a dyno sheet to go with that picture of the BP?

The above comments you've made Ted are the very reason why there's so much animus against you in the Rx7 world. There's absolutely no reason for the abrasive and caustic remarks you've made continually against me nor is it necessary here. I'm just like the next guy who's looking to build a better engine and do things better the next 'go around', but this kind of taunting and language from you does nothing to further your technical points; Infact, it will make people look at you like the jerk you really are and question anything you have to say, even if you are right. You're alienating yourself on rx7club.com and it'll quickly happen here, as well. I've seen some of your porting work that I didn't necessarily agree with but I didn't go off and lambast that work or make you appear to be blatantly incompetent in public or on one of these forums here. Instead, I'll salute you on the effourt done and look forward to good results. There's so sugar-coating or infidelity here; it's the truth.



Guys like you make my blood boil because of how arrogant and self-righteous you come off on these forums as if you're the "know-it-all" with next to NOTHING good or positively constructive to say to anyone about what they do. Perhaps you should post some of your bridgeported housings' pictures, from various angles, with explanations to the application, to substantiate just how skilled you are and why everything you say should be listened to.



If you had bothered to read the original posts, you would have learned that this bridgeport is done _conservatively_ as a way to add a little extra mid-range and top-end power plus give the bridgeported notoriety to the vehicle. I've done much more radical than this with the aforementioned "back cutting" you're speaking of. I'll let a photo illustrate:



http://bdc.cyberosity.com/pictures/T...d/DSC02079.JPG



Backcutting of the short radius of that eyebrow cut *was* done at two different points:



-) On the combustion chamber side, it was done with the same grinding stone I use to fine-edge the sides and bottom of the cut as well as tapering the closing timing. The angle isn't done sharp because the width of the eyebrow cut prevents nearly anything from getting in there.

-) On the port tunnel side, it was done there as well.



There was backcutting done. It's standard for me to do. Had I taken a picture from the perspective of the port tunnel, you would have seen it. You're mistaken and you're a jerk for the way you've come off. Nobody is going to "laugh at my BDC bridgeports" because those that are better than me see that I atleast have a solid idea of what I'm doing. Plus, they see that I'm out looking for constructive criticism to make improvements in my skill in doing them. Only a guy like you, who seems to thrive off the angered responses in threads like this, will even bring the subject up and try to turn a technical and mostly-enjoyed by the community hobby and trade into a veritable "pissing match". It reminds me of the bully kid in elementary school that tries to knock someone right back down that's trying their hardest to lift themselves up above their circumstances.



By the way, while we're on the subject Ted, where's the pictures of your bridgeports? Where's your cars that you've setup that you've learned from and experimented on to produce the best results you can? I managed to 499rwhp and 399.7ft/lbs of torque at 22psi of boost out of this car (two weeks after this dyno was done) with a *much worse* bridgeport (that had zero backcutting or closing timing tapering) than the ones you've seen posted here:



http://bdc.cyberosity.com/pictures/T...2/DSC01575.JPG



Where's yours?



B

not for nothing, ted, but youre failing to take into consideration the drastic difference of the start of the intake cycle. These bridge ports may look small, but make a LARGE difference on when air can start flowing into the combustin chamber. I have a BDC bridgeport in one of my cars. The plate is 'backcut' as you call it. It makes more power than my last HUGE streetport motor.

Take it easy guys.



When you say "back cutting" Is this what you are refering to:

https://www.nopistons.com/gallery/al...ridgepaint.jpg

Putting Brian on the spot like this a total bullshit. He's a big boy and as his last post shown he can hold his own.

But I will tell you what I do know. I know the motors I have seen Brian build like in Tony's car have proven his work for him. He is also a guy that will go way the hell out of the way to help people, even at least one that blew his motor because he was a dumbass and a broke dumbass on top of that.

He shares his ideas and how he actually does things that get the power he is able to get.

Hell most builders would not share that info and since they don't they are less susceptible to someone being over critical of their work and trashing them over it.

Brian will be the first to tell you that he learns new stuff all the time and is ALWAYS willing to listen to new ideas. He is one of the least confrontational people I know and not because he is a puss, but just because he is a good natured person.



This was very uneccesary and even if you don't think he does it to your satisfaction Ted there are ways to be diplomatic. Your point was structured in a way that everybody took offense to it. It was pretty much an all out attack.

I'm fine, Justin.



You're right on the picture, by the way. Someone pointed this out to me during the summer time last year when I was in the first stages of practicing and learning all about BP stuff. Although I don't know to what measurable, practical effect having the short radius (underside, underneath the inner water jacket o-ring) "backcut", but I suspect it will have an effect for the positive most definitely. If it's left with a 90 degree bend, then I don't believe it will work as well.



B

Only one way to find out... https://www.nopistons.com/forums/pub...#>/biggrin.png

I'll give it a shot on a secondary/auxilary bridge 6 port engine. I'll try disconnecting the secondary throttles... it should work.

You could always just machine a plate to go between the UIM and LIM, with only ports feeding the primary runners, and then pull the secondary injectors leads.

It'll be interesting.





Does secondary-only porting have an effect on emissions testing? With FC manifolds, it should have very little effect, especially on idle output.





Brian: I have always used a die grinder with carbide bits for my porting. Would you mind posting a pic of the rotary tool and all of the bits that you use? I'm curious.

Thanks.

As far as getting a bridge through, I had this idea for a secondary/aux bridge. Bridge the Secondayr and Aux ports, leave the promarys close to stock. Then machine a plate to go between the inkate manifold that would have throttle stops in the runner for the secondary and aux ports, operating like the Euro butterflies.

I figured I could get near 230wrhp and maybe get it through DEQ.

Sorry to hijack Brain.

I know I'm not the most "PC" person out there.

If it came across as a personal attack, then I apologize - this was not the intent of the reply. I wanted go get a valid discussion on the pro and cons of BDC's BP, and that's it. The reply was sent when I had to wait for a bunch of idiots building maintenance people for their annual pipe inspection, and I hadn't slept for over 30 hours - I apologive for coming across a little rough there.



I guess it all comes down to personal philosophy on bridge porting. I don't normally do them, and I don't like doing them on street, daily driven vehicles. I don't like the longevity question, and blowing a motor due to a failed bridge is not worth it in my book (for most people). I normally advise against it only in extreme circumstances. With that said, I have two BP projects under covers. One is definite, and it should be up and running within the next two months. This car is going to run a "secret" BP I'm going to try that should solve the longevity question; I want to see if the car will "run the numbers" and work properly before unveiling any info on it...if anyone cares.; the car is going to be an all out drag car. The other BP project is for a huge HKS T51R Kai 13BT, and the shop owner is busy getting his new shop in order before giving me the go ahead with the BP work.



BTW, that pic that I posted is a generic BP pic out of a Japan magazine. I dunno who did it or what kinda power it makes, but it's not my work. It's the same pic in my website.



Bottom line, we have vastly different views on what a BP should do, and I'll leave it at that.





-Ted

Ted,



In your opinion what should a bridge achieve over a large streetport? I'd like to know.

I don't know if tread jacking this is right, but I'll welcome to replying in a separate thread if another one initiated.



This is my philosophy about BP's...



The BP will compromise engine life - I'm sure we are all in agreement here.

I haven't seen proof of any BP design that will come close to what a SP longevity has - which is is basically 0% failure. This means that you're going to end up with a damaged motor - the question on how much damage due to the broken bridge depends on how good your luck is. With that said, I believe if you're going with a BP, why not go all out? The only compromise design is a "half" BP for those people who want a little more streetability in their engines. The failure of a half BP is still going to kill the engine just as much as a full bridge, but you do cut your chances in half. I think all bridges would've failed at around the same time (within 10,000 miles of each other), if given the chance - if they don't, then quality control and repeatability on porting technique is in question.



I would like to see comments by some of the more well-known porting gurus like Judge Ito, but I wouldn't be surprised in non-involvement on such a controversial thread. The information I've gathers on people who do BP's on a regular basis have formed my views on what a BP should and should not be; I trust these individuals, because they give me the straight-up info without all the sugar-coated BS. I've run BDC's pics of his BP's, and they have all confirmed my suspicions. I know it's not the nicest thing to do on a forum to challenge people (especially "gurus") on their positions, especially on their work - it always ends up being taken as a personal insult. I welcome BDC's (or anyone elses) comments/opinions/insults on MY work at any time - this is the only way I can *learn* when I can or cannot defend my work. I'd like to think I got a pretty decent grasp on BASIC engine dynamics, and anything that goes over my head I turn over to friends who are BSME grads.



I've known BDC for a long time, and we go way back... It hurts me to see his position stated on my challenge to his BP work by putting up the age-old "I've hit XXXhp (499 in this case), what have you done"; I find this defense a little lacking as anyone with a big turbo and a little knowledge could do this. So what if I beat 499? To me, this doesn't make me better than BDC, but does that legitify (is there such a word?) to BDC that I'm better? I would hope not, but why issue such a challenge in the first place? BTW, if it makes any difference, I do have a twin turbo project in the wings that should break 500rwhp on pump gas - I think that 499 run was made with a race gas mix? I think both [B}BDC[/B] and I started out FC3S/rotary engine experience at about the same time, with similar experiences going through FC's and Haltechs. He's lucky he got to mess around with bigger projects, as losing my job 3 years ago and losing almost all my stuff (tools, car parts, etc.) to some really stupid involvement with some bad characters have left me in a big hole at this point in my life; I'm lucky to be able to be involved with FC's/FD's and rotary engines in general in this point in my life through some very good friends, but having no money myself really cramps my R&D on potential projects.



I'd like to think my theories on rotary engines are made through objective thinking and reasoning. It would be nice to confirm them through objective testing, but my current financial situations limits that right now. If I come across other people's theories that I do not agree with, I tend to vigorously challenge such positions. I guess I'm doing it a little too vigorous, as people do get offended! Hell, I've cross paths with Judge Ito on some of his postings and pics on the other forum, but they have been cleared up after an initial flurry of miscommunication; I hope he's still not mad about that. https://www.nopistons.com/forums/pub...IR#>/smile.png I am a supporter of Judge Ito's work and theories, as many of my experiences have mimic'd his advice - I still think he's giving away too many secrets though! https://www.nopistons.com/forums/pub...IR#>/smile.png Case in point, I stumbled into the side seal problem by accident, and my intake ports have a very shallow angle on the closing end which is solves this problem; I was surprised to see the pinned post by Judge Ito at the top of this section addressing that very problem!



Anyways, I'm rambling too now...





-Ted

What's up fellas !!!!



Onle a few remember me running a half-bridge in my TII many years ago.

It was a full half-bridge w/ big street-ported sec's, rotor housings were notched and 45 degree of "back-cutting" was done.

Longevity was the same as my SP......had left plenty of material for the bridge. Motor ran for 10 months as a daily driver, a bit over 8k miles and ~440-450 rwh dyno pulls on pump gas(94).....later 495rwh (race gas). On that 495rwh run I put down 418lbs of torque.



Motor made nice torque and power for the boost...but I later realized I could not take full advantage of the bridge port without replacing the OEM TurboII intake and spinning the motor higher rpm(8-9krpm). Hmmm... FD intakes do flow more.



It sounded like a killer in the street.......but at the gas pump I would always get the same question.." needs a tune-up, huh??"



My .02

If it's so easy where's the proof you've done it? Where are the pics of your porting?



You always attack other people like this, but when the tables are turned you use the same old excuses every single time. "Anybody with a big turbo can do it" "I'm not about that high hp stuff" Give me a break. Shut me and all the others up Ted, show us once and for all what you've actually done.



Up until this last bit of crap this thread had some good info (if you knew who to listen too) I don't think there is 1 set way to port a motor, BDC explained the reasons for the type of porting seen in the first group of pics and it seemed to make sense to me.