Half Bridge vs. Street Port
Looking to hear from those of us who have had both.
Particularly in terms of a street driven car
I know the idle will be up and the vac down,.. how much?
Emissions?
Spool on same turbo?
Difference in whp with the other variables the same?
Difference in mpg with other variables the same?
Is the hbp really louder, with the same exhaust?
Any other insight into the real life differences is welcome.
Thanks!

 

over hear in the uk, there are a couple of guys who run HB RE engine with a HKS t51 and they arnt running any more BHP than people with a large street ported RE engine on the same turbo. Thats with engines/ V mount/ fuel set up/ tuning and dyno all done by the same tuners.

Main difference is spooling the T51, its about 1000 - 1500 rpm earlier on the BP, but noise, economy is worse

Torque is better on the BP but that may be to do with the earlier spooling

 

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good luck on what i predict will be similar outcome to the thread i linked.

 

wow is all I can say... lol

 

Might want to contact BDC. Question for argument will be how big a street port? I've seen street ports that were just plain ridiculous.

 

you didn't seem to see the thread in the rotary performance section?

 

BDC does great port work for both street ports and half bridges. He uses no machines but makes those ports as close to perfect as any machine could do. Have you guys seen his ports? If not here you go http://bdc.cyberosity.com/v/EnginePorting/

edit: I got his hbp and they look great! He has been a great help and actually is rebuilding my motor as we speak

 

Million ways to skin a cat.

Power is power is boost & fuel........port or not.

 

yeah as far as all out power I'm starting to see people not care to much about ports rather how big a turbo you can put on it. However if your not going all out and using a 2 step to launch with then a half bridge is great for the increase in turbo spool. I mean if we where going to argue with what port is better you can look at ken's 7.28 second half bridge and draw whatever conclusion you want from that but of course thier are just as fast rotaries out there with a little overlap and exhaust. I just think the half bridge is going to be a fun car that will help my t70 spool alot better than a street port could.

 

Overlap never hurt a turbocharged motor.

B

 

had both gas mileage from a bridge made me go back to a street. and certain tunners (will make enough power on street as they will on a bridge)

bridge is louder than a street!

youll probably gain 10-15 extra more horses.


bridge is good for big turbos as the power range is between 4000-8500rpm and the street is between 2700-8070rpm


half bridge idles at 1300rpm full bridge idles at 1500rpm street port idles between 800-1100rpm depending on how extreme the street is.



Honestly a half bridge gets annoying. and because of the gas mileage i would recommend staying with the street!

 

I have a half bridge port I love it. I wouldn't recommend it if the car was going to be driven a lot. The port spools the hell out of my T-78 which is really nice. It can get annoying sometimes when your in the car for a long period of time my ears ring for the next 3 hrs lol. Their is a vid in my sig of what mine sounds like

 

which i why i went back with the street. Since my rx7 is my only car i daily drive it! so i has to be streetable in some way.

 

can we lock this thread before flame war starts?

 

What? NO one has flamed or even gotten out of line. Go take your medicine and calm down.

 

stay with a stock motor if you are asking this question

 

see my sig
Gained extra power also I spool up 1000 rpm quicker, now a lot quicker pulling out of corners, gas milage for me is the same, but yes it will idle at around 1.2K to 1.3K and yes it is louder. Also my peak power arrives sooner and holds on longer to the peak power.
I wont go back to street as I luv the way HB spools up my turbo quicker therefore gets rid of any noticeable lag I had. Great if you are circuit racing

 

Ha! I knew some cybermouth was going to have to say that.
But on a street car it is a relevant factor.
If I can make 10% more power over a big SP with a 1/2 bridge at a cost of 50% worse mpg (hypothetically), it might not matter on a racecar but on a street car it matters, at least to me.
Total Cost vs Total Benefit
Thank you to everyone else.

 

he actually has a point. The rotary engine doesn't exactly have the reputation of having the best gas mileage around and if your thinking about going large street port or hbp the gas mileage is going to suffer either way you go. Lets face it no one here has a rotary because they are gas savers. It's a fun sports car that has alot of potential but the more you upgrade the worse the gas mileage is going to be, especially if you have a heavy foot. If your thinking in terms of gas mileage then yes stay with a stock motor.

 

I get about 10 mpg

 

riiight because my post had terrible advice.
and you asked about this
my insight to real life says...you need to search, rather than have us spoon feed your cybermouth

you are welcome

 

I am still running N/A for the time being on my half bridge, but if I were to do it over again I would probably just run a street port. The motor makes some pretty good mid range for an N/A, but overall it has just been kinda a pain to tune. However, I'm idling at a steady 1k without any brap, getting close to 15mpg if I don't have a lead foot, and passed emissions with flying colors with a little tuning and "minor modification"...

 

****, then what was the point of porting if you undid all the good stuff???

 

it might matter on a racecar too. we run enduro's in NASA (race car people, not the rocket people). 20% in gas mileage is the difference between making 2 fuel stops and 3. a fuel stop is roughly 2 laps, which is the difference between winning and being at the back....

 

Full Bridge Port! Only way to go!!!!