So after much discussion on this and other forums a few of us have come to a conclusion. None of us have ever seen a dyno sheet of a bridgeport or for that matter a peripheral port 12a or 13b that is not turbo'd. If anyone has sheets if you could post and a slight description of your setup that would be greatly appreciated. I am planning on building an engine soon, and i'm trying to gather ideas and information on what powerband I want because it is for my full time auto cross car.

 

i don't have the dyno sheet any longer as it was done about 10 years ago,but i still run the same combo block wise,my engine my 280 whp @9600 RPM,i have old school 74-78 13b rotors,racing geat carbon seals,racing beat Peripheral port housings,lots of oil system mods,i had a 51 mil weber 46 mil chokes

 

Bridge port + turbo = dyno sheet e-*****
Bridge port + no turbo = racer who doesn't want anyone else to see how much power he is (or isn't) making

 

so im stuck taking a shot in the dark... after about 10 years of doing this rotary thing i think im getting tiard of the dark secretes and pho-propietory knowledge everyone thinks they have. It's just like this in the US though. That's why the Auzzies and Puerto Ricans have a bigger and growing scean with faster cars. It takes a village to raise a car, and until we realize that rotaries will continue to be uncompetitive, like in ita, and things like pro 7 will continue to die.

 

I never understand it either, a dyno sheet can be posted without any name of the owner, what car its in, or even what type of racing its used for. The only exception would be the drag n/a guys which have so much power n/a it would be pretty obvious who owned it.

 

The rotary community is the most open one I know of. But still, when you have sponsorship and contingency money on the line, you need to make business decisions.

Perhaps my earlier statement was a bit *too* harsh, but the point is that most people who are free with their dyno sheets are merely building badass street(ish) vehicles and these type tend to either go for street ports, or they reach for a big turbo and some huge ports for it to flow through. Not too many people build heavily ported N/A engines for "street" use, it's for racing in classes that disallow turbos but do allow porting.

I thought cars in ITA and pro 7 were not allowed to be ported *at all*... Last time I looked at a pro 7 rulebook, the cars had to have 100% stock drivetrains right down to the solenoid rack, exhaust manifold, air pump, and OEM type converter. Where do you even find a 1st-gen that hasn't had some tweaker "YANK OUT THE RATS NEST OMG !!!" or hollow out the converter?

That's another point... the base cars are going up in value because most of them have been scrapped due to damage/rust/being junked because of stupid kid mods, so the ones that are left are not really cheap. Find me a $500 RX-7 in good shape and I'll find you someone willing to flip it for three times the price.

And really, racing kills cars, so if you care about the cars and the community, you'd do what you could to prevent people from racing them... every car turned into a race car is totalled, it just has not happened yet.

 

After 10 years of doing this you shouldn't have to ask this question.
Besides a dyno sheet may be able to point you in a similar direction powerwise but will not be the main deciding factor. Every engine is different and will have to be tuned differently. Also, drivetrain, suspension, cooling, etc are all things that are more important than a stupid dyno sheet. Dyno sheets don't mean squat, what really matters is the numbers at the drag stip or track. If you want all out max power than build a pport, if you want something with a little less power and a little easier on the wallet then build a BP and go from there.

Ps. The reason the Aussies and PR's are way ahead of the game because they spent the time and money in R&D and have been doing it for years. Very few people will just hop on the internet and show and tell all their major secrets. There's plenty of knowledge on the internet to meet your goals, but you will have to spend some time getting there. Good luck

 

If you want secrecy - go to the IPRA intakes thread at Ausrotary. Lot of hush-hush tuning going on... and mild bridge ports allegedly close to the 400hp mark, making good power over 7000 and simply not falling off... gotta be some BS but that's what's so nice about "secrecy", you may not be holding any cards at all but everyone else builds hype around it so it looks like you have an awesome hand. And all you have to do is keep your mouth shut, which is easy since you have nothing to spill, or maybe you did tell all of your secrets and nobody thinks it could be that simple...

I do really like the tapered runner, external fuel injector intake manifolds though! Enough so that I know what I'm going to be doing when I start experimening with composites...

 

Has anyone ever used RB bridgport templates? I'm looking to make peak power around 7500rpm with a useable power range from 5500-8500 rpm. Looking to have at least 210whp.

 

That's basically what I am using on my 12a rx2. I'm making over 200+hp to the wheels.

 

13B-PP
74 13B rotor housings with 50mm ports
GSL-SE rotors
3mm carbon apex seals
S4 e-shaft oil modded
racing oil pressure reg shimmed
front oil reg shimmed
factory mazda intake
weber 48IDA with 46mm chokes
fidanza 8lbs flywheel
ACT 6 puck clutch
4.44 rear gears


Things i still have to do is weld the weights in the distributor and lock the timing at 25-30 advanced at 6000rpm and redyno.

 

I still don't see why people would care that much about postin dyno results ... its not like you're telling them what you have done to the engine (ie port timing, intake lengths and tricks, or exhaust tricks. Pick up any piston magazine that does engine builds and everyday they spill a new bean ...

 

I think it would be really interesting to see this motor dyno from 2000 or even 3000 rpm. That engine makes more low end torque than most side port motors!
Not to pry, but are you running relatively long intake and exhaust runners?

 

You can tell your competiton a lot with numbers.

Let's say you're 3 seconds faster around a given course and your competition is eating themselves up trying to make more power. Then they see your dyno sheet and lo and behold your engine is making 25hp *less* everywhere in the useful powerband - then the lightbulb clicks and they realize they need to work on the suspension/driver and not the engine - and soon they're faster than you.

Or they might see that they don't have enough off-peak power...

The people who (as in, money depends on it) always keep secrets. Cam timing, cylinder head flow, special things done to the intake, exhaust setups...

 

Here is a pic of my intake setup



I dont have a pic of my exhaust but it is dual 2" pipe into 3" up and over the axle then dual 2". I have two magnaflow mufflers under the body and two edlebrock mufflers at the back.

 

You are way undercarbed and choking the engine down. With your port you should easily make around 260-280hp+. Not trying to be cocky but I am making more power with my small 12a bridgeport- standard bridge. You should be making way more power than me. Trust me, get a bigger carb, get a afr meter and egt meter, it will drastically help you tune and make all the power you can safely.

Get a bigger carb. 51+ and go 3" all the way from the header back with one high flow muffler.

 

Here's a picture of my carb/setup on my 12a- It is a modified 48IDA. The bottome is bored out to 51 and the top has been converted to 55DCOE boosters/venturies. Although, I am mainly set up for drag, I drive this car on the street all the time. You can at least do the 51 mod for around 275 bucks and this will help you out alot, but if you want my opinion I would save up for a 62MM Terminator II carb.

 

its hard to spend money. I have two son's and a wife. We built and race this car on a small budget. The engine cost $600 and the ports were made in the late 80's by my wifes father. The next toys are a injection perfection throttle body, microtech, nitrous and 11's i hope. But until then i will race the car the way it is.

 

With the above "toys", your going to spend several grand. If you just upgrade your carb, the low end-51 -$275.00, or the high end- 62mm TII carb $1200.00, you'll spend way less, total bolt on and I can guarantee you to go 11's on the motor only. No need to squeeze. I'm doing low to mid 12's with my 12abp.

If you know what your doing you may sqeeze a little more horsepower by going throttlebody and aftermarket ECU like MIcrotech, but that's if you're a master tuner. So that means you'll have to pay someone to tune for you. I am just giving you something to think about. Trust me, a carb setuup will be way cheaper and you can net just as much if not more horsepower with it. You have to learn how to tune the IDA and it is very easy if you get and AFR and EGT meter, they will be the best thing that you can buy regardless if you go carb or efi.

 

Never Looked at it like that ... thanks for clarifying.

 

EFI will more than likely make more power, but it will also make better power which will ultimately make the car faster. You can also tune the low end to be more tolerable. If you're planning on spraying, EFI will be a much better option as you can have a motor map and a bottle map, and not have to sacrifice power or retune when you want one or the other.

 

Wrong. A properly setup carb will allways make more peak HP than FI ever could. When the pressure drops across the chokes it causes a temprature drop that can't be duplicated in a FI setup. The colder intake charge will always net more peak power than any FI setup. The benifits of FI are the ease of tuning, more driveable, and you can acheive a broader power curve than you can with a carbed application.

I've never heard of using the 55 DCOE booster venturi. Is there a benifit to it as opposed to the long IDA one, or do you just have to use it when you bore the IDA to 51.5mm?

 

Umm I disagree with you completely there, FI has been proven time and time again to make more power everywhere including peak, please explain this temperature drop and why it cant be duplicated in a fuel injection setup?

 

I know of an engine thats almost identical spec, aside from smaller ports and chokes. Its in an Rx3 street car that runs high 11's at 113mph on semi-slicks with a 4.6 ratio.
Theres nothing wrong with a 48 IDA and in my experience there is little difference power-wise between a 48 and a 51 IDA.

Fuel injection definitely makes more power than a carb, and is much quicker and easier to tune. Value for dollar IDA's are hard to beat, but injection is the way to go.

 

Simple physics my friend. When the pressure drops across the chokes it drops the pressure in the float bowl and draws the fuel out and when the fuel atomizes in the low pressure it drops 20-100*F. It is impossible to replicate in a fuel injected application, and it's impossible for a fuel injected car to make more peak power because of that advantage. This can be seen in well tuned carbed applications when the intake manifold will freeze and get frost on it. My Turbo FB would have ice on the intake manifold after a few hard runs in 50* F ambiant temps. It was a street ported 13b with a stock s5 turbo blowing through a weber 45dcoe with no intercooler. FI is easier to tune and easier to get better numbers, but when it comes down to peak efficiancy you get a colder denser intake charge with a carbed application tuned to perfection. The reason some FI setups make more power than carb is because the carb is not setup correctly. As I said before Usually FI makes more power across more of the RPM band because it can be tuned for a broader range, but peak power can not be duplicated to a PROPERLY setup carb application.