I have someone that has a very good streetport that informed me that a streetport can produce just as much power as a bridge port and that bridge porting was over rated.

Now...

I am of the school of thought that bridge porting creates more port overlap, thus killing some low end power and shifting the entire power band slightly higher into the RPM's thus allowing for the production of more power.

Am I wrong here? I thought anything but a super aggresive street port wouldn't come close to a bridge port. What are your opinions on this?

Thanks guys.

-Maniac

 

for racing, you can't argue with decades of proof thorugh practice - so i'd say your friend is wrong. for the street, his argument holds water in my opinion. i'm a firm believer in aggressive streetports and i think with tuning they can significantly close the gap between street and bridge. by the time you get a bridge quiet enough for the street, it has lost some power.

 

From a racing point of view... not unless it's pretty wussy bridgeport. Granted, you can get a good streetport into the 240hp neighborhood (NA of course) but that's getting to the limits... and it's going to be on the peaky side too.

 

Your friend is 100% CORRECT! Bridgeporting is totally overrated. I made more power on a streetport than people made with a bridgeport with the same turbo. Racers like Demetrios K. who ran low 7's, ran a street port. So you'll make just as much power and gain more reliability with the street port.

 

Lets not close the book on this one. A turbo with little overlap vs a turbo with a lot of overlap its highly likely the one with less overlap that is going to win. All overlap does for a turbo is give time for the exhaust to revert into the intake stroke.


On an NA or SC engine this doesnt hold true. The exhaust pressure will be slightly over ambient or, in the case of a SC, much lower than ambient. In both cases the exhaust has momentum going out, not coming in. In the case of a SC'd car the overlap will actually give time for the blower to push out the exhaust contamination. In an NA car the effects will be much less, but still there will be momentum, and hopefully a well tuned exhaust, that helps to evacuate the chamber. In both of these cases it is likely that a BP will outperform a streetport in its powerband.


BC

 

This is a laugh. Of all of you that responded, how many of you have actually done it?

B

 

I hope you guys aren't going to start that BS again and say that so and so drag races with SP so they must be the best. You build the engine for the application at hand.

A bridgeport will make more power then a streetport.
And a PP will make more power then a BP.

If you allow an engine to accept more air what do you think will happen?

 

Care to waver a bet!

 

Enzo
You and I know different. They try allternate ports but leave every thing else on the motor to support a street port and expect it to work. The problem is that because some cannot figure out the combination they bash the others who have. It's funny because both you and I know what the top rotaries are running not to mention the very same ones bashing the BP or PP have not even make the power that the very same guys with BP and PP have made with street ports.

 

+1 to that.

B

 

Yes we do...

But yet people like to argue and ride the bandwagon that SP is the only way to go..

 

Never said so and so, I said "ME". I would rather have a SP than the BP. If you get anymore power, its not going to be that much and the reliablilty suffers big time because of how close its cut to the water jacket. So that being said, I'd still say "Yes, the bridgeport is overated". You loose bottom end so if you drive on the street you won't be happy either.

 

Has this been your experience with bridge ported motors or are you just speculating?

 

That would be a "no" on the first part and a "yes" on the latter for him.

B

 

It's one of those "stay inside the box" things, Enzo. You must stay in it because you're not supposed to go out of it.

B

 

I mean this is easy right? Just post some dyno sheets of motors with the same supporting mods (turbos, ect.) with a street vs a pp vs a BP. I am sure you guys have them?

I think Ernie is making a good point about the streetability of BP motors, I have not read many rave reviews about those driving them on the steet.

 

I've been daily-ing mine for 2 1/2 years. It drives just fine. Infact, I drove it all the way from here in Tx to Alabama, up to TN, back down to AL, then back home. 2000 miles. Runs perfectly fine.

The reliability issue is a moot point and is a false stigma that stems from years gone where some of the non-turbo race car guys would cut ridiculously-large bridgeports well past the water jacket o-ring land that would require some sealant or other trick once the o-ring was cut. The other issue has to do with the width and thickness of the bridge that's left over once you make your bridgeport cut. I have almost 40 bridgeport engines out there, all for street use, and not a single complaint nor broken bridge or anything else that would support this whole "reliability" notion.

The facts are simple when it comes to BP's and PP's. Induce overlap, produce substantially more torque, all else remaining the same. It works much, much better than a street port.

Edit: One more thing I wanted to add -- notice the people responding positively about bridgeports are those of us who've actually done it. Most all of us will say we're never going back to a street port. But, those that argue against it, are those that are speculating from a point-of-view that isn't experiential. Rhetorically speaking, why is that?

B

 

Here we go again....

B, you and possibly all your BP motors you have built are a good example of what Crispeed stated :
"They try alternate ports but leave every thing else on the motor that supports a street port"
What have you done differently for the BP ?
Don't remember ever seeing any of your logs going past 7.5krpm !!!!
Don't remember you or any of your motors making a substancial or even more horsepower over a SP under same conditions.

Show me facts/dynos that make your small eye-brow BP better then SPs.
Some people just love that "brap...brap...brap" sound !!! :-).

JD

 

With a small eye-brow type of bridge which barely goes past rotor housing edge reliability is not an issue but its gains in flow vs the added overlap is the main argument.
Out of 40 BP motors how many are making over 500rwh ?
How many have gone back to SP ? ( I personally know of 2 and are happier now).

Then explain why your dyno sheets contradict your preaching?
I made more torque on a stock motor w/N-S stock twins and pump gas then your 24psi single turbo methanol injected BP setup !!!
You have yet to prove your point since your 1st BP motor !!!

Ok, you have done it but NOT proved anything.

JD

 

i drove an fd with a sp , then the same car with a bp, good single turbo, good exhaust , good tune , etc. The powerband was moved way up to the point that it was not nearly as powerfull under 4500 rpm. Sure , above that it made more power but it wasn't worth the trade off in my opinion. not for a street car anyway.

 

Lemme pose a simple question for all of you to ponder. Since we're talking power and reliability here, let's just talk race cars since we're discussing power and reliability for race car purposes. If bridgeporting with forced induction is such a great thing for a drag race only rotary engine then why is it that NONE of the consistantly fast record breaking rotary drag racers run it? Now before any of you bridge port guys answer this by saying that you have to know the right combination, have experience with it, etc. remember this, racers bridgeporting rotaries have been around for a LOOOOOONG time now, you mean to tell me that no one has figured out the right combo yet?, OR could it be that bridge porting has been tried in numerous ways with forced induction and it just doesn't work as efficiently and reliably in a high boosted forced induction application as a street port OR a semi pp?

 

Holy ****,what a can of worms.

BP is the way,if you want low down ,then go buy a blinking V8

karis

(Streetport is something i would give to the wife to drive)

 

And how do you know that those racers are not using BP, semi PP, or BP + semi PP engines?

I can't really say if its a fact, but I remember seeing a famous fast 3/4 car engine being pulled at NJ; maybe my eyes were deceiving me, but I swear I saw a semi PP

 

Yes, a semi pp, NOT a BP.

 

Oh gawd, here we go again...

I don't think it's a question of RACE-ONLY applications - I think the answer is obvious to this.
BDC likes to argue about streeting BP's...

Personally, I'd rather go PP for full-race.


-Ted