bridge port and turbo?
12-06-2005, 03:50 AM
#11
Senior Member
Join Date: Dec 2003
Posts: 162
Actually Bell does make reference to situtations where P2/P1 <1. It's not generally dwelt upon, as in order to get it you end up with something that is a pure race engine with all the drawbacks that entails.
I have some evidence off some of the australian race engine builders that they have this situation quite freqently on high boost rotary drag race engines.
I have some evidence off some of the australian race engine builders that they have this situation quite freqently on high boost rotary drag race engines.
12-06-2005, 10:33 PM
#13
Member
Join Date: Jun 2005
Posts: 49
Originally Posted by j9fd3s' post='784033' date='Dec 5 2005, 10:57 AM
look at howard colemans setup, he's got 2 turbos and i think he's running about 21psi backpressure @15psi boost. imagine how big his turbos would have to be on a pp motor....
https://www.nopistons.com/forums/ind...howtopic=54978
OK, got ya. And yeah, howard's setup is the one i was referring to, couldn't remember the name...
So...what if I wanted a PP engine, turbo(s), 400-500hp on pump gas...I would either have to get a huge turbo or get a smaller responsive one and suffer all thr drawbacks of high backpressure, right?
If this were just a "I did it cuz I wanted to car" and not a hardcore racer or anything, what would be good turbo choices for single and twins? A laggy turbo for a street ported 13B would spool better on a p-port?
Owen
12-07-2005, 11:58 AM
#14
Senior Member
Join Date: May 2002
Location: California
Posts: 22,465
Originally Posted by REZCAR' post='784447' date='Dec 6 2005, 08:33 PM
OK, got ya. And yeah, howard's setup is the one i was referring to, couldn't remember the name...
So...what if I wanted a PP engine, turbo(s), 400-500hp on pump gas...I would either have to get a huge turbo or get a smaller responsive one and suffer all thr drawbacks of high backpressure, right?
If this were just a "I did it cuz I wanted to car" and not a hardcore racer or anything, what would be good turbo choices for single and twins? A laggy turbo for a street ported 13B would spool better on a p-port?
Owen
if you only want 400-500hp then pp is prolly not a good choice. people make that with a street port, or stock ports and higher boost.
12-07-2005, 07:48 PM
#15
Senior Member
Join Date: Dec 2001
Location: Okinawa Japan at McDonalds
Posts: 472
I've said before and I will say it again. The only drawback to running a half bridge turbo on the street is NOISE. After running the bridge and stepping back down to the side I can say this.
12-09-2005, 10:50 PM
#16
Senior Member
Join Date: Jul 2002
Location: DC
Posts: 875
Originally Posted by IGY' post='784660' date='Dec 7 2005, 05:48 PM
I've said before and I will say it again. The only drawback to running a half bridge turbo on the street is NOISE. After running the bridge and stepping back down to the side I can say this.
Well that means bridgy's for everyone!!! Well for meee!!
12-29-2005, 11:20 AM
#18
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Join Date: Jun 2003
Location: Grand Prairie, TX
Posts: 917
Originally Posted by IGY' post='784660' date='Dec 7 2005, 05:48 PM
I've said before and I will say it again. The only drawback to running a half bridge turbo on the street is NOISE. After running the bridge and stepping back down to the side I can say this.
I agree. I'll post more on this topic as well.
B
12-29-2005, 12:07 PM
#19
Senior Member
Join Date: Jun 2003
Location: Grand Prairie, TX
Posts: 917
Regarding the turbocharged bridgeport idea ...
There's been alot of debate over this for atleast the past couple of years or so. I believe much of the negative stigma associated with bridgeporting comes from the normally-aspirated world where problems with overlap are evidenced clearly. However, when throwing a turbocharger into the equation, it becomes a monkey-wrench and things don't turn-out as one would expect. Prior to any of the BP-turbo stuff I delved into, I only knew of one person (John Duarte/Boostn7) who'd experimented with it and ran it for awhile. He eventually went back to a street port for unbeknownced-to-me reasons. Before then, I'd never heard of anyone who was running any kind of BP-turbo setup on any well-tuned EFI system, let alone anywhere. That doesn't mean it never existed; I'd just never run across anyone doing it. So, as best as I can figure, prior to about three years ago, it wasn't an alternative that many would consider viable. The norm was doing your typical street-port variant with a different turbo. Not quite three years ago, I started experimenting with the half-bridgeport turbo platform. I was initially against it and for many months prior to being "arm-twisted" into doing it on a friend of mine's car. My opinions about the setup pretty much echoed Bill Shurvington's. I was adamantly against it and was sold on the idea that it wouldn't work. Well, I turned out to be wrong about it. As many other times in our rotary history, this was yet another discovery that wouldn't seem to work well at all on-paper but, surprisingly enough, turned out to be not only a viable alternative to street porting but a significantly-improving one. I was amazed by the results -- better turbo spool, much better mid-range, and a high-end curve that didn't fall off. I've been working with these ever since (going on 2 1/2 years now) and, like a few have already said, I won't go back. Throughout my research and experience with these setups over this 2 1/2 year period of time, I've found that the bridgeport-turbo combination can yield higher power output figures with lower boost levels and can run a larger-than-normal turbocharger while still maintaining the feel of a street-port turbo combo (all things remaining constant). These positive effects have been echoed over and over again by those that have chosen to experiment with this setup. It seems to be quite a worthwhile option to those that want to delve into it. Many of those people are now BP-turbo advocates where they once may've been skeptical.
The bridgeport-turbo platform isn't without its complications or downsides, however. It does pose a much greater need for fine tuning via a good standalone EFI system. There's just not much getting around this with the exception of having a linear-run vehicle like a straight-line drag setup. I've spent this entire time working on making better fuel curves and leading/trail-split ignition maps for these setups and am still not considering them to be perfect. From what I've experimented with and done over this time, I've come up with ignition stuff that's fairly more radical (in places) compared to your typical stock or street port setup. Another downside associated with these has to do with the difference between half and full bridgeporting. I'll admit that I've not yet experimented with full bridgeporting on a turbo setup, but I suspect the effects are the same -> a "pushed up" power-peak, earlier spool of a turbo and thereby earlier and more aggressively building torque curve, etc. However, the more overlap that is added in to the equation, the more loss of very low-end (below 1500rpm) is found. This is yet one more factor that a stock injection system can't account for very well and one that further emphasises the need for a good, tunable EFI system and professional tuning. Another thing I have found that gives rise to potential tuning issues is how little of a change in shape, width, and heigth the bridgeport cut can exacerbate drivability problems. Even just the smallest change can add a significant amount of overlap into the equation which makes it all the more difficult to tune for tip-in and for idle. I am not sure of what this would be like on a full-bridgeport; only a half. What I've personally found is to go for the half-bridgeport in using two smaller-sized cuts. The benefits of better spool, better mid-range and exceptional high-end (along with the cool, lopey bridgeport idle) are in their glory yet are not diminished by the tunability issues. Here's an example of that:
http://bdc.cyberosity.com/v/Porting/NeerajTandon/
The work done on this motor is what I call my Spec-C half-bridgeport. This particular one was done on a 13BREW just recently. It's my old "mainstay" of a scheme that has proven to work well for street use. The cuts aren't very long or wide at all with comparison to that of some of the more radical bridgeporting schemes that are floating around out there. To be greatly effective, they don't need to be large. They also don't need to be so big and all-encompassing that they threaten the water jacket o-ring land or march into it requiring some sort of hack-job on the o-ring. The o-ring cutting as well as the issue regarding making the actual iron bridge too thin is what creates the reliability issues that many have risen against this setup. When sticking to smaller cuts such as the ones these alleged reliability issues are a moot point.
In my business, I have alot of questions posed to me about this setup. While I am pro-bridgeport turbo all the way, I do tell my customers that "you've got to have your i's dotted and t's crossed if you want to pursue this setup". Extra care needs to be taken in selecting and matching up a properly-sized turbocharger to the application. A good deal of focus also needs to be applied when looking at heat-elimination type things such as heat-blanketting the turbine housing, ceramic coating exhaust pieces, better intercooler, ceramic coating of intake manifolds, etc. I suppose much of this is true for any good setup but I feel that it needs to be more of a stressed point in this case. There's also the noise factor that's been brought up -- depending on the size cuts done on the housings for the bridgeports, there will be a dramatic increase in exhaust noise (to the tune of 50% or greater loudness).
On a side note Sureshot, the rotor beveling job you did looks very good. However, I've got my concerns about its efficacy as a port-modifier as well as the effects on crank balancing. I wouldn't mind hearing more about this as I do not know a whole lot about it.
B
There's been alot of debate over this for atleast the past couple of years or so. I believe much of the negative stigma associated with bridgeporting comes from the normally-aspirated world where problems with overlap are evidenced clearly. However, when throwing a turbocharger into the equation, it becomes a monkey-wrench and things don't turn-out as one would expect. Prior to any of the BP-turbo stuff I delved into, I only knew of one person (John Duarte/Boostn7) who'd experimented with it and ran it for awhile. He eventually went back to a street port for unbeknownced-to-me reasons. Before then, I'd never heard of anyone who was running any kind of BP-turbo setup on any well-tuned EFI system, let alone anywhere. That doesn't mean it never existed; I'd just never run across anyone doing it. So, as best as I can figure, prior to about three years ago, it wasn't an alternative that many would consider viable. The norm was doing your typical street-port variant with a different turbo. Not quite three years ago, I started experimenting with the half-bridgeport turbo platform. I was initially against it and for many months prior to being "arm-twisted" into doing it on a friend of mine's car. My opinions about the setup pretty much echoed Bill Shurvington's. I was adamantly against it and was sold on the idea that it wouldn't work. Well, I turned out to be wrong about it. As many other times in our rotary history, this was yet another discovery that wouldn't seem to work well at all on-paper but, surprisingly enough, turned out to be not only a viable alternative to street porting but a significantly-improving one. I was amazed by the results -- better turbo spool, much better mid-range, and a high-end curve that didn't fall off. I've been working with these ever since (going on 2 1/2 years now) and, like a few have already said, I won't go back. Throughout my research and experience with these setups over this 2 1/2 year period of time, I've found that the bridgeport-turbo combination can yield higher power output figures with lower boost levels and can run a larger-than-normal turbocharger while still maintaining the feel of a street-port turbo combo (all things remaining constant). These positive effects have been echoed over and over again by those that have chosen to experiment with this setup. It seems to be quite a worthwhile option to those that want to delve into it. Many of those people are now BP-turbo advocates where they once may've been skeptical.
The bridgeport-turbo platform isn't without its complications or downsides, however. It does pose a much greater need for fine tuning via a good standalone EFI system. There's just not much getting around this with the exception of having a linear-run vehicle like a straight-line drag setup. I've spent this entire time working on making better fuel curves and leading/trail-split ignition maps for these setups and am still not considering them to be perfect. From what I've experimented with and done over this time, I've come up with ignition stuff that's fairly more radical (in places) compared to your typical stock or street port setup. Another downside associated with these has to do with the difference between half and full bridgeporting. I'll admit that I've not yet experimented with full bridgeporting on a turbo setup, but I suspect the effects are the same -> a "pushed up" power-peak, earlier spool of a turbo and thereby earlier and more aggressively building torque curve, etc. However, the more overlap that is added in to the equation, the more loss of very low-end (below 1500rpm) is found. This is yet one more factor that a stock injection system can't account for very well and one that further emphasises the need for a good, tunable EFI system and professional tuning. Another thing I have found that gives rise to potential tuning issues is how little of a change in shape, width, and heigth the bridgeport cut can exacerbate drivability problems. Even just the smallest change can add a significant amount of overlap into the equation which makes it all the more difficult to tune for tip-in and for idle. I am not sure of what this would be like on a full-bridgeport; only a half. What I've personally found is to go for the half-bridgeport in using two smaller-sized cuts. The benefits of better spool, better mid-range and exceptional high-end (along with the cool, lopey bridgeport idle) are in their glory yet are not diminished by the tunability issues. Here's an example of that:
http://bdc.cyberosity.com/v/Porting/NeerajTandon/
The work done on this motor is what I call my Spec-C half-bridgeport. This particular one was done on a 13BREW just recently. It's my old "mainstay" of a scheme that has proven to work well for street use. The cuts aren't very long or wide at all with comparison to that of some of the more radical bridgeporting schemes that are floating around out there. To be greatly effective, they don't need to be large. They also don't need to be so big and all-encompassing that they threaten the water jacket o-ring land or march into it requiring some sort of hack-job on the o-ring. The o-ring cutting as well as the issue regarding making the actual iron bridge too thin is what creates the reliability issues that many have risen against this setup. When sticking to smaller cuts such as the ones these alleged reliability issues are a moot point.
In my business, I have alot of questions posed to me about this setup. While I am pro-bridgeport turbo all the way, I do tell my customers that "you've got to have your i's dotted and t's crossed if you want to pursue this setup". Extra care needs to be taken in selecting and matching up a properly-sized turbocharger to the application. A good deal of focus also needs to be applied when looking at heat-elimination type things such as heat-blanketting the turbine housing, ceramic coating exhaust pieces, better intercooler, ceramic coating of intake manifolds, etc. I suppose much of this is true for any good setup but I feel that it needs to be more of a stressed point in this case. There's also the noise factor that's been brought up -- depending on the size cuts done on the housings for the bridgeports, there will be a dramatic increase in exhaust noise (to the tune of 50% or greater loudness).
On a side note Sureshot, the rotor beveling job you did looks very good. However, I've got my concerns about its efficacy as a port-modifier as well as the effects on crank balancing. I wouldn't mind hearing more about this as I do not know a whole lot about it.
B
12-29-2005, 12:53 PM
#20
Senior Member
Join Date: May 2002
Location: California
Posts: 22,465
ive driven a well sorted na full bridge car and the only downside is the idle/cruise, everything else is better. the full bridge na, made more power from 2000rpms, than my gsl-se's do. it just bucks under 4500rpms, making cruising a pain.
the car had enough muffler under it that while you could hear it coming, it wasnt louder than say a honda with a fart can....
the car had enough muffler under it that while you could hear it coming, it wasnt louder than say a honda with a fart can....