What are the Pro's and Con's between a big Race Port and Half Bridge?...

Taking into consideration Power, Reliability and Drivability....

 

What's a race port? You mean a peri port?

Half bridge has a possibility of being driven on the street. PP's have none.

 

race port, like a HUGE street port....

 

usually, a race port implies a peripheral port, as that's the only "true" race port.

A huge street port vs. a half bridge......it really depends, N/A vs. Turbo.

Since you're from Canada, I'm going to assume that you either a. have a TII or b. imported a J-spec TII, so we'll talk about Turbos. Comparing these engines in NA trim is an entirely different subject.

I'm not the best person to ask about turbos, I've only owned one (out of 4) and prefer to foucs on NA.

That being said:

Driving feel and power:

For driving feel, the HBP crowd is adamant that you get quicker spool time, leading to increased feel and drivability. They are also admant that for the same setup, all else being equal, the HBP will make more power.

The SP crowd counters with, if we have different setups, we can make just as much power as the HBP crowd.

That being said, my opinion is that if you're starting from scratch and deciding which port to use, then the all else being equal argument is thrown out the window. That is, since you're starting from the ground up, you can select a power goal that you want to hit and pick the port and the appropriately sized turbo from the start. The only advantage from one over the other at the planning stages, is that you know the HBP will give a quicker spool time, even if ultimate power figures will be the same on different setups.

Drivability/Streetability

The going argument from the HBP crowd is that the HBP is perfectly streetable, which I do agree with to some extent. BDC has been driving his HBP for the past three years, with few problems, a fact that he always likes to show off with. Kudos to him, I say, for making a port work for him. The SP crowd really doesn't have much to worry about, since the SP stands for STREETport.

My personal take is that, even though I own a rotary, gas prices being high as they are, I'm still looking to maximise every last drop of fuel that I can. Here, the obvious nod goes to the SP, since mileage has always been a weakness of the BP and HBP motors.

Reliability/Longeivity

This seems to be a very sensitive topic for the HBP crowd. I'll preface the next statement by saying, On average, history has shown, that the early failure rate, as a percentage, of HBP has been higher than that of SP's. Now, this is historical data, and if the current trend of BDC-styled HBP's live up to their reliability standards, then the gap is significantly closed. Early HBP's weren't cut right or cut too deep, making those engines week. I haven't heard many customers of BDC complain that their engine has failed prematurely. Since SP's seem to account for the larger part of engine builds, SP's tend to have a higher failure number. That's really only due to the law of averages.

In the end, the decision is up to you. While I wouldn't mind the increased boost response of the HBP, mfun is secondary to cost efficiency for me, and so I would stick to the streetport in order to have fun while trying to save as much gas as possible.

 

? Canada got NA's too you know, but yes, it's a JDM TII.

 

I know, but it seems like most of the FC owners nowadays that post from Canada are driving the Turbo variety. So I made a reasonable assumption.

Do they still have good free Stampede breakfasts? I hear that they've recently been of the well, lacking, variety.

 

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/bridgeport-vs-1-2-bridge-584583/

heres a good thread on the HBP vs. a full BP.....

as well what do you plan on doing with the car?

ps: link is not working???

 

definitely, the important questions is what do you want to do with the car? That lays the groundwork for how your should proceed.

I think you linked it wrong, upon inspection, there's two http://'s in the link.

 

A huge street port is just that, a street port. Any street port that flows like a bridge is going to be wildly unreliable since the side and corner seal ends will be virtually unsupported.

A race port typically would mean peripheral. The only real issue with peripheral ports is that to quiet them down for street use means choking the exhaust, which kills the power.

Really the answer depends on your goals.

If you want to make 400HP, then a street port is fine. If you are looking for more, then you'll want to bridge if for no other reason then the fact that it will spool that monster two much faster then a street port (and it will make more power, but I don't want to start that debate again).

 

I am glad I read this thread.. cause I was planning to steeet port my new S5 T2 engine and this supports that what I want to do and the goals I have a SP will be the way to go


Dave

 

Watch this:

Street driven P Port

Anything is possible.

 

Sure, it can drive on the street, will it be civil, will it suffer from throttle jerks at constant throttle situations? will you wake up the whole neighborhood, town, county if you don't choke that exhaust? If you do choke the exhaust, why not just have a street port where you can get the same power level, with none of the additional compromises. Will my wallet be dry after all the gas money I'm going to have to put in that thing?

Anything can be driven on the street. I could drive a 787B with a 4-Rotor PP on the street if I have money. The question is, is it feasbile?

 

Peripheral ports tend to behave better then bridgeports in regard to bucking and light throttle issues. It's all in the tuning. Much of the bad press that bridges and peripheral ports get is left over from the days of carburetors. Fuel injection helps a lot.

 

Fuel consumption is not determined by porting, but by the quality of tune of your EMS.

My friend runs a HBP w/ a T-70 and nets 22 mpg during cruise on the highway.

 

First, tell us what your power goals are. A good streetport can break 500+ rwhp pretty easily with the right turbo combination.

 

Behave better......but not as good as an SP of course.

I've heard of streetports hitting 28 mpg/highway, joining the very exclusive 400 mile on a single tank in an S4 club. Some of them were Turbo's as well. I'm sure RETed would love to tell you about his trip. I think J-Rat nets 24 city on his 10th AE SP. I personally made 24 mpg highway on an SAFC tune w/ no timing advance. I've hit the 400 mile on a single tank in an S5 mark. I've never heard of any half-bridge/bridge/semi-peri/peri that can come even close to that. I would say that's due to the difference in port.

 

Talk to "mazpower", he'll tell you about it.

 

Yeah, but what's his city mileage?

My car gets great mileage on the highway but once it's in the city things change drastically. High overlap ports do not like low RPM operation and need a LOT more fuel to operate smoothly.

 

That's why I didn't mention city mileage.

 

when i hear race port i think of the "monster" port

 

I dunno I like mine full bridged and all, used to drive it all the time, until summer came...Only so many days I can go with out AC

 

i'm going to be using my BNR3 for the time being and the half bridge from what i understand wouldnt work nicely with the turbo, but my goals are around 500whp at most, and ofcourse i want power, i will be buying a bigger turbo in the future since i have to sell mine for a rebuild....

i want streetability and reliability, to see me net just under 300whp on a mustang dyno before it popped has got me set on rebuilding the engine since the rest of the car's done, i want to track it, auto X, road course, everything, so mid 400whp is pretty much what i'm looking for....

hope that helps....

 

Well I know a T04E 57 & 60 trim turbos will spool verrry quick with a HBP. The 57 trim will peak around 380rwhp-ish and the 60 trim should get right at 400rwhp or so. They are both very peaky and right at the edge of the surge line at those rates.

 

so, how would a half bridge react with a BNR stage 3 turbo?...

 

of course it would spool super quick, but would max out too quick and not hold max to redline. In all essense, the engine would out breathe the turbo with flick of a wrist