ok... I have a 12a bridgeport, its a daily driver, drives like a gem and I cant get enuff of the brap brap brap idle... all you ppl saying bridgeports are not streetable obviously havnt driven a nice bridgeport setup, or cant drive lol.

 

How big is the bridge? Any pics of the engine build up?

-Marques

 

no pics of engine build up sorry. but it puts about 180hp to the rear wheels, although it feels like more and idles at about 1300rpm nicely. Revs to 10,000rpm easily too not that i do that often if at all...

 

If people are caiming 200rwhp for a streetport, a bridgeport that only gives 180rwhp must be quite small and an unusual shape with emphasis on porting out.
If that is the case surely overlap is not significant and the brap brap is in the ear of the beholder.

Therefore with this port shape it is possibly streetable in spite of 1300rpm.

 

What apex seals are you using for that 10,000 rpm?

-Marques

 

I think most of the people on the forum use the porting terms a bit too loosely. To say "my streetport/bridgeport makes xxxHP" doesn't mean a whole lot. All it does is give a poor basis for comparison. I mean, the name only describes the port type, you could have a mazdatrix template, or something you've done yourself to make it larger. In which case, you should elaborate. Saying something like, "my 12a mazdatrix streetport with a 48dcoe, and RB streetport exhaust makes 160rwhp," is a bit more accurate, I'd say.
Anyways, my point is, when you look at/type in these numbers, just keep that in mind.

 

jayrot- a very good point. In Australia streetports come in two types mild and extended.

Mild is porting where you enlarge the port while keeping the same shape. Its size is limited by the path of the corner seals. Its very driveable.

Extended is when you go wide to the corner seal line but the shape is elongated to really delay the port closing. In its ultimate form there is little difference in its performance, and that of a mild bridgeport which keeps the original size and shape, and just adds the outside second port.

Thus, under the generic name 'streetport' you get a wildly different power curce and output. But the critical point with both is to have good input and output systems. You can actually go backwards if they dont match.

I once started a thread to quantify different port specs but got nowhere. As Carl said the biggest difference of all is the dyno you are using and the day you do it.

As a matter of interest your example of 160rwhp was spot on, was it based on actual experience?

Are there any differences between the Mazdatrix and Racing beat templates?

 

jayrot? whaaa? it's a C! heh
Yeah, you see a lot of differences between port designs, even within a specific type. There's just no clearcut definition outside the shape. From what I've noticed, people who get real good don't use templates, but understand the engine well enough they can go by what they think will work given what they want in terms of HP how much low end that want to give up, etc...
I've got a mazdatrix streetport template, and plan to mess with their bridgeport template sometime soon. A friend of mine is putting together a SP 12a now using the mazdatrix template I got, but I don't have first hand experience with any ported motors, although I plan to very soon. I came up with that number based on what I know about the increases mazdatrix claims, and the increases from those mods. Seemed like a good estimate.
I don't know if they're different or not, RB says theirs was developed in house, but mazdatrix doesn't mention it, and theirs is about $5 more than RBs.

 

I'd like to see a dyno chart of a 12a streetport putting 200 to the wheels.

My 12a J-Bridge, ceramic apex seals, Dellorto 48dhla 42mm chokes and very high flowing and extremely loud exhaust put 205 to the wheels with 30 degrees timing. Kicks and bucks when driven under 4000rpms. Too much overlap! I couldn't imagine driving it on the street!

A 1300rpm idle on a bridge. I bet it's not a J-bridge, mabye a standard bridge or an eyebrow port. Mine idles @ 1800rpms a steady brapp-brapp-brapp. doesn't studder or cough.

$.02 given!

 

The 200 hp was in reference to a streetport13B 4-port, which fitzwaryne said would only produce only 146 hp. I don't know if he meant with the stock catalytic converter, air pump, fuel, and anemic induction, etc. but I was definitely basing the higher figure on upgraded components, and as an upper range.

I agree with the porting comments there are different sizes and shapes more along a continuum than simply one or two.

In planning the porting a suggestion is to have in mind the type of intake manifold you will be using, (i.e. partially stock components, or custom fabricated) and item such as injector sizes or carburettor size/type, and if modified rotors used

 

lol... I havnt dyno the car, 180rwhp is what the old owner guest it was... however i wouldnt be suprised if it was more... Its got a 4 barrel holley on it, dont know what size and high flow 2 1/2 exhaust.... got 2 fuel pumps, one for cracking and one for cruising

 

and it does go brap brap brap.... i luv it, ppl look at ur car like wtf is that thing w0000t

and yes i am a n00b to rotories :P

 

dyno thay puppy heb09! I'd like to see what a 4bbl holley can put out!

 

I want to dyno it.. but I dont want to have it revving its heart out for so long :S I know every1 says rotors like revving, but its still metal on metal and I dont know if its worth to dyno it. Usually if I want to have a play i'll rev out to 6 1/2 but anything after that and the fan belt starts sqeek/slip.. tried to tighten it up but can get the alternator to budge, its pretty tight as it is. time to find a rotary shop... I've only owned this car for 5 days
I'm definitly hooked on rotors I would like to rev out to 10,000rpm but not while it sqeeks :S

 

dual
belt
pullies

110psi oil pressure regulator
17.5mm oil pump
-10 oil lines

is what it needs

 

Out of interest I checked other threads for data on the typical performance of a Streetported 13B-4p. The only result I could find was on the dyno thread where RiffRaff gave 136rwhp on his mild streetported 13B with a RB exhaust system. I also checked 13B streetport outputs for some old school rotaries and 140-150 rwhp was typical. We are a bit more clued up now so I still reckon around 180rwhp for a 12A BP and 150 for a 12A BP with idles around 1200 and 1500rpm respectively while fuel usuage would be 16mpg and 12mpg..

There are always going to be exceptions, and variations due to the the extent of porting within the generic description. But at least the data gives a good general starting point for decision making.

 

Good post fitzwarryne.

My REPU will get dyno'd next year and I will post it here. It's got 13b 4-port with some streetporting and real nice intake and exhaust system. Should be add current data to the benchmarks.

Brad

 

is a holley or a webber better?
i know holleys are better on fuel right?

 

Going on that alone I think the 12a/13b hybred should be able to put atleast 10 to 15rwhp more.
I think this should put me within an exceptable bracket. Not quit the 100:1 that I want but close enough considering that it would be rwhp not fwhp.

 

what a load of s**t.. If my bridgeport used that much fuel, how have I done 400km in the last 5 days and only put in 50 litres of fuel, and still have atleast 10 litres in the tank?!?!?
Get your facts right...

 

heb09- you claim you are getting the equivalent of 24.3 mpg average in your bridgeport. This is a consumption rate that many stock ported RXs do not achieve.

My posts were to expect 9mpg in competition and 12mpg over all. Bridgeport drivers tend to use the potential of their engine. These figures were based on numerous examples.

For example, I suggest you look at the posts on this thread for objective evidence from other drivers. The data is:-

wackyrotary 14.5mpg driving in country areas
karlsm 12.2mpg
12abridgeport 11.0mpg
AD RX 8.7mpg

If you achieve 24.3mpg all I can say is you must have an exceptional light foot, or inaccurate instruments.

If you have numeracy problems in understanding US measurments then compare your claimed 10litres per 100km, with AD RX at 28 litres per 100km.

 

well I have a bridgeport and I;m talking from first hand experience, not from what other ppl have posted. sure if i put my f00t down i can almost see the gauge moving (well not really) but i dont drive my rx7 hard all the time because i dont wish to blow my engine any time soon...
guess i have an exceptional light foot because if my instruments were lying, wouldnt i have run out of petrol? I guess i am just annoyed that ppl try put bridgeports down because of fuel consumption, but u have to feed the horses at the end of the day. So anyone wanting to bridgeport their 12a, dont even worry about fuel consumption. If your worried about fuel, then dont drive a rotor

 

heb09- obviously you must have a very efficient set-up, what type of carb and exhaust system do you have? Do you have any details of your port opening? Is the port shape flattened rather than elongated as is becoming more of a fashion for streetports

 

AMEN to that!!! well im building a 12a Bridgey and even though i drive about 90km a day just to and from work, i want to have some more power on tap for the weekends.


If you want a bridgey, you alrady should know that yes your fuel will go up, but its the same with any car. U want the horses you give em more food :P

-James

 

Bridgeport is such a wide spread term, it's very hard to compare one to another.

I've seen a bridgeported motor that had it's bridges less than 1/2in long. It's still going to give you a brap brap brap sound and of course eat way less fuel with just a little better top end than a street port.

In my opinion bridgeports can be very cool but on average make too much noise for the power they put out unless they are in a super light car.