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Bridgeport vs. 1/2 Bridge ?

Old 10-11-06, 07:04 PM
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Originally Posted by BDC
Good Lord, I don't even know where to start. With all due respect to the forum membership here... so many "experts" yet so few people here who have any actual, real experience with this.

I've got 3 1/2 years with turbo'd bridgeports under my belt and it was a path of experience that I was initially against. Needless to say, I was drastically wrong about my original preconceptions about it. The one thing I've learned philosophically about all of this is to never open your mouth about something that you know little to nothing of. That same philosophy applies here to this porting ideaology. It works, it works extremely well, with few downsides, but within certain parameters. The "problem" with it is there's so few people doing it, and even fewer "standards" out there that people will adhere to, for it to really be a competing point-of-view for the time being.

I'll write more on this later. I could write a book about this.

B

Please, give us more. I am wanting to learn more about bp and hbp motors. You are the only person whom others have spoke highly of on this subject. So, the only way to set standards and protocol for standards is through experimentation and the results drawn from such experimenting.
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Old 10-11-06, 07:55 PM
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Thumbs up

Alot of my writing about this centers around the differences between bridgeports and street ports on a turbocharged application. I'll focus on those differences primarily in my response here.

As I eluded to earlier today, basically this whole idea of doing a turbo'd bridgeport setup was something I was initially against. I'd spoken to Don Marvel about it about 4 years ago and his opinion of it wasn't one that was optimistic. Otherwise, I hadn't really known many people who had experimented with it except John Duarte. And, for reasons unbeknownced to me, he's elected to go back to a street port. Other than that, when I initially did my first one, I hadn't known anyone who'd really pursued it to the degree that I and a few others have been doing for the past 2-3 years. My friend Tony had been harassing me for awhile to do it on his (half bridgeport) but I was against it based on what others said even though they had no first-hand knowledge let alone being completely ignorant of how to actually make the cuts.

Long story short, to my surprise the before/after difference was amazing. I still stand by it today. Boost built earlier in the RPM band and with much ferocity, overall power seemed to be higher, and the high-end power did not drop off. Mind you, nothing else was changed on this motor setup at all; just fixing a sheared outer water jacket o-ring and adding two bridgeport cuts that were 1/8" wide and 1.25" in length.

One thing I've learned about turbocharged bridgeport applications is that seemingly small changes made to the bridgeport eyebrow cut can yield fairly radical differences in noise levels, low-end drivability, low-RPM gas mileage, as well as overall high-end power. The overall conclusion of my experience with these is that a conservative half-bridgeport with smaller-sized, conservative cuts yields a very beneficial and appealing combination of the advantages of the bridgeport (earlier port opening, earlier and harder boost thresshold, considerably higher peak power) while still retaining excellent drivability characteristics and still good gas mileage. The car can still start and run in the cold weather just fine, can still be crisp and responsive like a stock or street ported motor, and can still perform just fine on the streets while having that cool "brap brap", lopey idle and the more "hotrod" sound of a rotary. I stand firm on this claim and, along with being an owner of one of these setups myself, I will never go back to a street port.

Here's a visual example of the kind of port I'm referring to:

http://bdc.cyberosity.com/v/EnginePo...geViewsIndex=1

In the circles of the community as it stands in the present time, there seem to be several objections to using a bridgeport for the street, even though generally speaking they lack objectivity and merit:

- Lack of reliability
- Peaky power
- Loss of low-end drivability
- Loss of fuel mileage (gas-consuming "pigs" is one quote I've run across)

These claims, without any substantiation, are entirely false on their face. Every bit of this, again, goes back to the size and shape of the bridgeport cut that's being made, as well as the # of cuts being made on the motor (whether it be two for a half-bridgeport or four for a full-bridgeport). The issue of reliability, in as much as I can figure, stems from the old school NA bridgeport days when people either made the iron bridges leftover (after porting the standard port outlet and cutting the bridgeport cut) too thin or if the bridgeport transcended into that of a J-Port where it protruded into the inner water jacket o-ring land, therefore requiring some sort of hack-job sealing at the now two ends of the o-ring. The kind of bridgeporting that's being done, albeit on a smaller scale by a few of us in this community, doesn't lend itself towards these reliability problems whatsoever. The iron bridges are left nice and thick and there's no protrusion into the o-ring land on the iron housing. In all honesty, the size of the port doesn't need to be the size of a lemon to produce power. The overall paradigm for making power comparatively here is different -- we're talking about turbocharged applications where the engine is relying on an external air pump (the compressor) rather than its own aspirative ability. The other objections (gas-guzzling, no low-end, peaky power) are false as well. The only one that has any shred of merit would be the gas-guzzling claim but I wouldn't call it that. Granted, with the advent of overlap in the motor, and at lower RPMs where that overlap is physically "more present", there's going to be a loss of mileage, but again it depends greatly on the shape and size of these bridgeport cuts. If they're left conservative, it's minimal. Highway gas mileage is not much different at all. My "gas guzzling" car still yields slightly over 20mpg on the highway at 80mph in 5th gear at 3300-3400rpm.

The positives -- The way a half-bridgeport engine over a street ported engine fleshes itself out in the real world is that it yields the ability to use "more turbo" -- namely the use of a larger turbocharger all together (compressor and turbine), all else being equal. On its face, it tends towards reliability: Using a larger exhaust can yield lower turbine inlet pressures in the exhaust manifold area. Using a larger compressor can produce more power with the same boost pressures with lower IAT's (intake air temperatures). Since the motor has considerably higher VE (volumetric efficiency) over a stock or street ported motor with minimal overlap, it can turn a much larger turbo (or set of turbos) while still producing the same, if not better, boost thresshold and "feel" of a standard-sized turbo. It can also take better advantage of a larger and more efficient compressor, such as a Turbonetics T66, while continuing to build power past the point where a stock or street ported motor has begun to starve for air (6-7krpm ranges). This is why I believe, when it comes to porting in general, opening the port earlier is what yields more power over closing the port later. The higher the engine spins, the less physical time it has to injest and exhale a "gulp" of air. With a bridgeport, the port is opening so early that the peak power RPM is extended, not shifted, substantially higher. It's the best of both worlds.

All in all, when it comes to this or anything else for that matter that "steps outside of the box" or crosses the lines of "orthodoxy" the community has set forth as being the accepted norm, I highly advise for those that are reading that they only listen to those people who've actually done it or are very closely related in some way to those that've done it and have real, practical experience. There's so many so-called "experts" on these forums that have so little real-world experience that, while they can talk a good game and can appear knowledgable, their words I think should only be taken with a grain of salt.

B
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Old 10-11-06, 07:57 PM
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Originally Posted by RotaryResurrection
That's kinda odd, it goes against everything I've seen and heard of. The more air you can efficiently move into the engine at low rpms, the faster you can spool a turbo. It has been my personal experience that cars that go from Sp to HBP spool faster with all else being equivalent.
Mine too, Kevin. That's what caught my attention to all of this in the first place and forced me to change my mind about it.
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Old 10-11-06, 08:27 PM
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BDC, how much do you charge to hbp a set of irons? Thanks for the info!
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Old 10-11-06, 08:33 PM
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Excellent write up BDC.

BC
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Old 10-11-06, 09:09 PM
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woowoooooo! now as i'm sure alot of that "expert" jive was directed towards me it's all goooood. we say the same about alot of builders on this forum. first off i'd like to say my whole deal in this thread was to kick up the fire. i know you don't know me bdc, but you do know my good buddy neil. we tuned his setup today for 15psi on the Q-trim MPt70 and it is A W E S O M E !!!!!! he hits 15psi by4300rpms in 4th. the boost never dies from shifts and it pulls like a got damn freight train.

i've been planning to do a hbp since i found out he had one, which was about ummm... i dunno 2 years ago? i do have real world experience with them AND full bridges. i still don't care for the full bridges and turbos but i DO like the HBP setup. i love how it NEVER stops pulling. shift at 7k, 8k, hell 9k it doesnt matter. it keeps pulling!

so enough with the bs, and i apologize if i threw you up in a storm of aggrivation on all this

we're putting alcohol injection on his car soon and will be tuning for 20+psi.


and for reference on his car. @ 1/4 throttle it will still make around 10psi just cruising, has great low end drivability, and the mileage is so-so. still rich on the cruise, but we'll get it worked out.

i'll post videos soon
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Old 10-11-06, 10:07 PM
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It wasn't directed towards you, Zac. Infact, there wasn't anything directed specifically at anyone.

B

Originally Posted by No_Rotor_RX7
woowoooooo! now as i'm sure alot of that "expert" jive was directed towards me it's all goooood. we say the same about alot of builders on this forum. first off i'd like to say my whole deal in this thread was to kick up the fire. i know you don't know me bdc, but you do know my good buddy neil. we tuned his setup today for 15psi on the Q-trim MPt70 and it is A W E S O M E !!!!!! he hits 15psi by4300rpms in 4th. the boost never dies from shifts and it pulls like a got damn freight train.

i've been planning to do a hbp since i found out he had one, which was about ummm... i dunno 2 years ago? i do have real world experience with them AND full bridges. i still don't care for the full bridges and turbos but i DO like the HBP setup. i love how it NEVER stops pulling. shift at 7k, 8k, hell 9k it doesnt matter. it keeps pulling!

so enough with the bs, and i apologize if i threw you up in a storm of aggrivation on all this

we're putting alcohol injection on his car soon and will be tuning for 20+psi.


and for reference on his car. @ 1/4 throttle it will still make around 10psi just cruising, has great low end drivability, and the mileage is so-so. still rich on the cruise, but we'll get it worked out.

i'll post videos soon
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Old 10-11-06, 10:08 PM
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Originally Posted by NMJ87T2
BDC, how much do you charge to hbp a set of irons? Thanks for the info!
I'll shoot you a PM on it.

B
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Old 10-11-06, 11:17 PM
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Originally Posted by BDC
It wasn't directed towards you, Zac. Infact, there wasn't anything directed specifically at anyone.

B

ok thanks i told neil i probably got out of hand on the anti- hbp games. hahahaha i just can't wait to see how mine does with TWINS!!!!!! woowoo! my only deal is, the only bridge ports we've done are mostly intended for n/a setups... = pretty large and open early as well as close late. you seem to have your timing setup pretty set for the eyebrow so maybe i'll just send the irons your way? i dunno. i'm going to modify some templates and i'll contemplate it some more

shoot me a pm as well please for the cost of just doing the porting on the two irons, i'll already have it streetported and all. just need the eyebrow thanks bro!
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Old 10-11-06, 11:58 PM
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Originally Posted by BDC
Boost built earlier in the RPM band and with much ferocity, overall power seemed to be higher, and the high-end power did not drop off.
Earlier boost implies more power, but it doesn't.
Overall power? I doubt it.
High-end power? Sure.
I've already proven this before that your "499rwhp" did not make more power under 4kRPM than my measly 253rwhp on DynoJet plots.
All I hear is all kinds of excuses.


The overall conclusion of my experience with these is that a conservative half-bridgeport with smaller-sized, conservative cuts yields a very beneficial and appealing combination of the advantages of the bridgeport (earlier port opening, earlier and harder boost thresshold, considerably higher peak power) while still retaining excellent drivability characteristics and still good gas mileage.

(blah blah blah)

All in all, when it comes to this or anything else for that matter that "steps outside of the box" or crosses the lines of "orthodoxy" the community has set forth as being the accepted norm, I highly advise for those that are reading that they only listen to those people who've actually done it or are very closely related in some way to those that've done it and have real, practical experience. There's so many so-called "experts" on these forums that have so little real-world experience that, while they can talk a good game and can appear knowledgable, their words I think should only be taken with a grain of salt.
Be careful of what you read and what you hear over the Internet - that's true.

Here is the facts (I'm sure BDC will correct this is any of it is wrong):
Tony Farkas - ~480hp @ 23psi @ ~7250RPM (on HKS cast manifold, etc.)
I believe there's a dyno sheet floating around for this number.
This car (I think?) also was the same one that did the 499 number, but I can't find any dyno sheet for that run.
Our own J-Rat - 434hp @ "right around 20psi" @ ~7,000RPM ON A STOCK PORT 13BT MOTOR (on HKS cast manifold, etc.)

http://not2fast.wryday.com/turbo/glo...rbo_calc.shtml

Plug the numbers into that above link...

BDC's HBP on Tony Farkas' FC made...15hp more than J-Rat's STOCK PORT motor.

So, I ask again, is the (H)BP worth it?
15hp for all that trouble?
The numbers are indisputable (unless I fucked up on my recollection).

Let the whining and excuses begin...


-Ted
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Old 10-12-06, 07:05 AM
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Originally Posted by BDC
In all honesty, the size of the port doesn't need to be the size of a lemon to produce power.
Well that's no fun.
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Old 10-12-06, 09:10 AM
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Originally Posted by sniperstevedave
Could you restate that, Aaron Cake? That last paragraph is confusing me. You tried aux portts as an experiment, haven't taken it past 4K yet, say its easy to drive at the low end with no noticable lack of torque. Yet you say they should not be considered, and one should go half or full. ???
I can see how that could be confusing. My writing style is sometimes unique in that it makes perfect sense in my head yet when it hits the page...For example the metal store has gotten used to me sending in orders that list pieces of sheet metal as "2MM thick by 12 inches long by 1.2 meters wide".

Anyway, what I initially meant is something like this. I don't recommend the aux bridge because it still has some of the "disadvantages" of the bridgeport without all the advantages of a half-bridge.

The overlap still produces the "brap brap" idle and can cause some minor bucking down low (though keep in mind that my EMS is still untuned and there is 1.7KM of driving on the engine). I personally like the idle but there seem to be those who don't. I guess over time it could get annoying but I'm not expecting to have problems with the ricers wanting to race me like I did before. And this car is kind of loud....

I have not noticed any significant loss of low end torque as compared to a 6 port engine with the sleeves removed. Meaning that I can still drive around at 2K without major issues, and rev it up to 2.5K to get moving initially. Once it's tuned and the idle is less then 1500RPM and the A/F ratios are more sane (as well has having a little more timing advance then 0 degrees!) I expect the low end to improve signifantly to the point where in normal driving conditions I could slip the clutch at ~2K to get going. Keep in mind that all this is under very light loads.

Free revving, there is hesitation under 3.5K but after 4K the engine wants to fly to redline. Since the engine has all new bearings and so little mileage on it I have not driven it past 4K under any load. Also compounding that is if I go past the injector stage point (3500 RPM) without enough load (manifold pressure about 5") the 1600 CC secondaries come on and flood the engine with fuel...built in rev limiter at 4K. Once I get some miles on the engine I'll have that tuned out.

I expect that once the engine is broken in (at this point, looking like next spring because it is now cold and snow is predicted within a week...) and rough tuned it will fly at the top end even with the stock turbo. All indications have shown that the turbo wants to spool around 2K and part throttle (witness my "that was boost" comments in the video...) so it's going to make boost instantly under heavy throttle. When I get the real turbo on there it should spool nicely almost as low (either GT35R or some custom TO4 made locally). Keep in mind that this is a high compression engine as well...

Clear as mud?

Edit...Forgot my final point.

Now the reason I say to do a half bridge is because all this will be amplified. More aggressive port timing means a better spooling turbo, and larger port area means more flow...So a half bridge (as opposed to an aux bridge) has more potential but both have the same "drawbacks".
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Old 10-12-06, 10:44 AM
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Originally Posted by RETed
Earlier boost implies more power, but it doesn't.
Overall power? I doubt it.
High-end power? Sure.
I've already proven this before that your "499rwhp" did not make more power under 4kRPM than my measly 253rwhp on DynoJet plots.
All I hear is all kinds of excuses.



Be careful of what you read and what you hear over the Internet - that's true.

Here is the facts (I'm sure BDC will correct this is any of it is wrong):
Tony Farkas - ~480hp @ 23psi @ ~7250RPM (on HKS cast manifold, etc.)
I believe there's a dyno sheet floating around for this number.
This car (I think?) also was the same one that did the 499 number, but I can't find any dyno sheet for that run.
Our own J-Rat - 434hp @ "right around 20psi" @ ~7,000RPM ON A STOCK PORT 13BT MOTOR (on HKS cast manifold, etc.)

http://not2fast.wryday.com/turbo/glo...rbo_calc.shtml

Plug the numbers into that above link...

BDC's HBP on Tony Farkas' FC made...15hp more than J-Rat's STOCK PORT motor.

So, I ask again, is the (H)BP worth it?
15hp for all that trouble?
The numbers are indisputable (unless I fucked up on my recollection).

Let the whining and excuses begin...


-Ted
No "whining", no "excuses". Are you trying to bait me? Projecting what you assume others would do based on how you yourself would respond? Already attempting to pre-emptively dismiss and compartmentalize my and others' responses to your alleged "proofs" as being "excuses" even before we've ever written a single word? You haven't changed much.

It's all just practical, real-world experience. I didn't originally like the whole bridgeport turbo idea myself but it seems to work. You've been on this anti-bridgeport trip for well over 2 1/2 years now, but I've still yet to see you even make one (even though you've been threatening to do it forever), let alone try and mess with one in person. Again, give it a try Ted. It may pleasantly surprise you, or are you so emotionally committed to your point-of-view that you'll forever, staunchly refuse?

A couple of responses to your technical objections:

- You've not "proven" a thing against my claims. That's from a thread on NoPistons from early '04; It was a comparison of your car and Tony's car. I remember the graph you'd drawn out. You claimed that "in a race to 4krpm, you'd win". First off, the scenario is unrealistic and ridiculous. Who's going to race from a dead stop to 4krpm? Give me a break! Secondly. Max and others caught you playing funny with the numbers to try and lend strength to your argument. Thirdly, you were intellectually dishonest when you refused to consider the other facts about this: Your car's got a stock turbo, his was a larger-than-QTrim setup w/ a large shaft and supposedly had, as you've claimed, "less" low-end, yet amazingly enough it was still able to accelerate one of those turbos to the point of making gobs of power in the mid-range. Stick your foot in your mouth, Ted; you proved our point without even knowing it.

- Boost, in and of itself, is an ambiguous number and means nothing without a few other qualifiers. You're aware of this, right? Comparing boost figures doesn't yield bonafiable, comparative output power figures based on some rigid scale. 10psi of positive output pressure from a T66 will automatically yield a hell of alot more power than the same boost from a stock turbo. The same rule applies to this turbo of his -- a Schwitzer S300 which is rather small on the compressor side. Tony's hotside was also too small for the application; a 0.83 A/R housing, the only one we could find for the turbo.

As I've asked you a zillion times in the past, I'll ask you again -- show me some real-world experience instead of relentlessly trying to somehow debunk my claims. Are you ever going to actually do some of this stuff or are you that guy that instead just plays armchair quarterback? Bark about theory and numbers all you'd like, but the real world is where the rubber meets the road. And, funny enough, those that've done it all seem to swear by it.

B
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Old 10-12-06, 11:01 AM
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No "whining", no "excuses". Are you trying to bait me? Projecting what you assume others would do based on how you yourself would respond? Already attempting to pre-emptively dismiss and compartmentalize my and others' responses to your alleged "proofs" as being "excuses" even before we've ever written a single word?
Who, RETed? NEVER!
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Old 10-12-06, 11:13 AM
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Wow, I just love the rhetoric you like to spew.
I don't believe you were an English major in college?
Nice try to make you sound more intellectual than you really are.
It might work on some of the other more gullible RX-7 owners...

Yeah, I guess you're up to your own same tricks.
I don't remember half of that you claimed, but then again my memory isn't the greatest.
Fudging the numbers?
How is that possible when I took the numbers verbatim from dyno plots posted.
I'd like to hear how that was possible.
Unrealistic of a race which had an artificial 4kRPM limit?
Sure, I'm not going to deny that.
Fact is that I clearly made more power under 4kRPM - it was a statement given the facts from the Excel graph from posted dyno sheets.
Nothing more, nothing less - again, more whining.

See, the problem is that you think you've made some miraculous discovery...all on your own.
That I find hard to believe.
Others (i.e. Mazda Racing) have been messing with this stuff longer than you - longer than me - and you'd think they would've figured it out years ago?
Thinking outside the box?
I doubt it.
It's been done; you just don't want to admit it.
Just because you haven't seen proof of such claims doesn't mean it doesn't exist.
You make it sound like your broke some rigid laws of physics - you didn't.
My above post just proves you didn't do anything incredible.
Sure, it makes power - I never denied that.
But you're boasting about something that isn't that spectacular - I just proved that too.
Just because you like to claim you've found some new "technology" in porting and having all these ignorant RX-7 folk kiss your *** makes it so?
No, not necessarily - that's my point.

You're making power with some half-assed porting? Yes.
Claiming this half-*** porting is the answer to all your power needs? No.

Sorry about taking so long about disproving your claims - I'm still digging myself out of a big hole.
Actually, I might never get to do so - I still think BP's are a waste of time.
I'm already planning on skipping BP's and jumping straight into PP's at this point in time, so you can have your BP's all you want.

Good luck, cause everyone knows this thread is going to turn to muck now.
All I asked was to quantify your numbers, and you still like to bring up all the negatives - all you had to do was explain why only the 15hp gain; nothing more / nothing less.
That last reply didn't even manage to address that, but you had plenty to throw a lot of mud at me.


-Ted
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Old 10-12-06, 11:15 AM
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Originally Posted by BDC
And, funny enough, those that've done it all seem to swear by it.
Although I've yet to have the HBP motor I was talkign about run in yet, I can tell you I'll be pleased with it.

Its going to make the power Im shooting for (mid- high 300's) and its giong to sound like a rabid monster.

Could the same power (relatively speaking) be made on the same turbo with a stock or street port? yes. But I think the biggest difference will be in location and length of the powerband - which will be higher and longer with the HBP.

The question of reliabilty, as you've mentioned, lies more so on the actual cuts itself then in the blanket statement of "BP's are less reliable than stock or street ports". And since mine is *fairly* conservative, I don't forsee any major issues with it.

I think the main point of the comparison between the two is that both CAN make large numbers, they simply have their own quirks when reaching the limit. Quirks in the actual difference between powerbands - the rest is pretty well moot.

Fuel mileage is somethign I don't really consider a factor in a HBP or BP, or for that matter, a high HP stock or street port. Because honestly - who is going to build a +300hp (rotary) car to drive on the street and really watch their fuel mileage? doing it for interest and curiosity is one thing, but anyone building a car like that and is worried about losing fuel mileage or having bad mileage has their priorites mixed.

I still stick by my opinion that BP's are *mostly* for ego in a turbo'd setup. They have their benefits, but for most people (who aren't well versed in turbo'd BP's) there are risks associated with taking the leap that can all be avoided by doing a simple street port - all the while making neglgibly close HP to what it would be with eyebrows.

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Old 10-12-06, 11:20 AM
  #92  
BDC
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Originally Posted by RETed
Wow, I just love the rhetoric you like to spew.
I don't believe you were an English major in college?
Nice try to make you sound more intellectual than you really are.
It might work on some of the other more gullible RX-7 owners...

Yeah, I guess you're up to your own same tricks.
I don't remember half of that you claimed, but then again my memory isn't the greatest.
Fudging the numbers?
How is that possible when I took the numbers verbatim from dyno plots posted.
I'd like to hear how that was possible.
Unrealistic of a race which had an artificial 4kRPM limit?
Sure, I'm not going to deny that.
Fact is that I clearly made more power under 4kRPM - it was a statement given the facts from the Excel graph from posted dyno sheets.
Nothing more, nothing less - again, more whining.

See, the problem is that you think you've made some miraculous discovery...all on your own.
That I find hard to believe.
Others (i.e. Mazda Racing) have been messing with this stuff longer than you - longer than me - and you'd think they would've figured it out years ago?
Thinking outside the box?
I doubt it.
It's been done; you just don't want to admit it.
Just because you haven't seen proof of such claims doesn't mean it doesn't exist.
You make it sound like your broke some rigid laws of physics - you didn't.
My above post just proves you didn't do anything incredible.
Sure, it makes power - I never denied that.
But you're boasting about something that isn't that spectacular - I just proved that too.
Just because you like to claim you've found some new "technology" in porting and having all these ignorant RX-7 folk kiss your *** makes it so?
No, not necessarily - that's my point.

You're making power with some half-assed porting? Yes.
Claiming this half-*** porting is the answer to all your power needs? No.

Sorry about taking so long about disproving your claims - I'm still digging myself out of a big hole.
Actually, I might never get to do so - I still think BP's are a waste of time.
I'm already planning on skipping BP's and jumping straight into PP's at this point in time, so you can have your BP's all you want.

Good luck, cause everyone knows this thread is going to turn to muck now.
All I asked was to quantify your numbers, and you still like to bring up all the negatives - all you had to do was explain why only the 15hp gain; nothing more / nothing less.
That last reply didn't even manage to address that, but you had plenty to throw a lot of mud at me.


-Ted
The only person that will turn this thread into "muck" is you. Thanks for your response.

B
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Old 10-12-06, 02:44 PM
  #93  
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Originally Posted by RETed

Good luck, cause everyone knows this thread is going to turn to muck now.

-Ted
It only goes that way when you seem to chime in and somehow speak from your years of "hands on experience" with the HBP and BPs with countless hours of dyno tuning and experimentation. You are probably better off in a street port thread if you even know that.

<3 E.
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Old 10-12-06, 06:42 PM
  #94  
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Originally Posted by Aaron Cake
I can see how that could be confusing. My writing style is sometimes unique in that it makes perfect sense in my head yet when it hits the page...For example the metal store has gotten used to me sending in orders that list pieces of sheet metal as "2MM thick by 12 inches long by 1.2 meters wide".

Anyway, what I initially meant is something like this. I don't recommend the aux bridge because it still has some of the "disadvantages" of the bridgeport without all the advantages of a half-bridge.

The overlap still produces the "brap brap" idle and can cause some minor bucking down low (though keep in mind that my EMS is still untuned and there is 1.7KM of driving on the engine). I personally like the idle but there seem to be those who don't. I guess over time it could get annoying but I'm not expecting to have problems with the ricers wanting to race me like I did before. And this car is kind of loud....

I have not noticed any significant loss of low end torque as compared to a 6 port engine with the sleeves removed. Meaning that I can still drive around at 2K without major issues, and rev it up to 2.5K to get moving initially. Once it's tuned and the idle is less then 1500RPM and the A/F ratios are more sane (as well has having a little more timing advance then 0 degrees!) I expect the low end to improve signifantly to the point where in normal driving conditions I could slip the clutch at ~2K to get going. Keep in mind that all this is under very light loads.

Free revving, there is hesitation under 3.5K but after 4K the engine wants to fly to redline. Since the engine has all new bearings and so little mileage on it I have not driven it past 4K under any load. Also compounding that is if I go past the injector stage point (3500 RPM) without enough load (manifold pressure about 5") the 1600 CC secondaries come on and flood the engine with fuel...built in rev limiter at 4K. Once I get some miles on the engine I'll have that tuned out.

I expect that once the engine is broken in (at this point, looking like next spring because it is now cold and snow is predicted within a week...) and rough tuned it will fly at the top end even with the stock turbo. All indications have shown that the turbo wants to spool around 2K and part throttle (witness my "that was boost" comments in the video...) so it's going to make boost instantly under heavy throttle. When I get the real turbo on there it should spool nicely almost as low (either GT35R or some custom TO4 made locally). Keep in mind that this is a high compression engine as well...

Clear as mud?

Edit...Forgot my final point.

Now the reason I say to do a half bridge is because all this will be amplified. More aggressive port timing means a better spooling turbo, and larger port area means more flow...So a half bridge (as opposed to an aux bridge) has more potential but both have the same "drawbacks".
As for confusing writting style, that's pretty common. I still have trouble with clarity when discussing deep technical topics, but I am getting better.
As for the aux bridge, I am not sure how it is even possible to lose low end torque or power, since the ports only open at high rpms. Perhaps you have done something barbaric like removing the sleeves? Actually, this is understandable since you turbocharged a n/a engine and no longer need them. However, my interest in an aux port is for a naturally aspirated 6 port (S5), not a turbocharged one. I am wondering if it might make a large increase in top end power, without affecting the low end. Since my car is a daily driver, and will be for some time to come, I do not want to lessen low rpm performance, while maximizing high rpm performance, since when I drive for fun I will be staying at high rpms anyway. Do you (or anyone else) have any first hand info on an aux bridge in this respect?

As for the two of you (you know who I am talking about) I have noticed that neither of you is posting dyno charts, and humbly request that until that changes you take it somewhere else.
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Old 10-12-06, 06:56 PM
  #95  
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He actually posted that the sleeves were removed.

I think a bridged aux port with working sleeves would be especially cool because a bridge port would never pass smog here uless you have a hookup. Even a rough idle can knock you out of the running on visual....and swapping an engine in and out isn't so easy as the straight pipe that alot of people use .

I figure that, with the sleeves closed, you would have the drivability, smoggability, and gas mileage of a street port with considerably higher top end.

So...I am curious to see the results as well.

--Alex
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Old 10-12-06, 07:20 PM
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I am not sure why a bridgeport wouldn't pass an emissions test, it shouldn't have any problems as long as it is properly tuned and the engine is in good condition.
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Old 10-12-06, 07:28 PM
  #97  
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Originally Posted by raptor22
because a bridge port would never pass smog here uless you have a hookup. Even a rough idle can knock you out of the running on visual....and swapping an engine in and out isn't so easy as the straight pipe that alot of people use .
Move somewhere like TN. The rednecks here could care less about the environment.
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Old 10-12-06, 07:35 PM
  #98  
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Originally Posted by sniperstevedave
I am not sure why a bridgeport wouldn't pass an emissions test, it shouldn't have any problems as long as it is properly tuned and the engine is in good condition.
It's a high overlap setup. Think of it like a 2-stroke motor -- it's highly emissions unfriendly. How would you "properly tune" something like that to pass?

By the way, regarding your "dyno sheet" comment, a dyno sheet isn't the end-all, be-all deciding factor in whether or not something is efficacious for our setups. This can apply here, as well. There's an ever-growing number of people that agree with the claims I've made and that a dyno sheet, while helpful, isn't necessarily, ultimately needed to prove them.

B

Last edited by BDC; 10-12-06 at 07:53 PM.
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Old 10-12-06, 07:58 PM
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Originally Posted by sniperstevedave
However, my interest in an aux port is for a naturally aspirated 6 port (S5), not a turbocharged one. I am wondering if it might make a large increase in top end power, without affecting the low end. Since my car is a daily driver, and will be for some time to come, I do not want to lessen low rpm performance, while maximizing high rpm performance, since when I drive for fun I will be staying at high rpms anyway. Do you (or anyone else) have any first hand info on an aux bridge in this respect?

Im taking delivery of what you are talking about on saturday. it will be untuned and has a ways to go until it is optimized, but Ill keep you posted if you are interested.


BC
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Old 10-12-06, 08:22 PM
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Also, with respect to the dyno sheet, those were two entirely different setups. If I read the posts right, they had pretty different turbos, which greatly effects the output and power band.
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