hi guys i have a fd3s s7 rx7 and am wondering if its possible to run a half bridgeport on the stock twin turbos, which are non sequential. emissions have also been removed, and will be run with a power fc ecu. is this safely do-able

 

Yes. Off-hand I'm not sure what the motivation would be for doing that, but yes.

 

since they will obviously physically bolt up to the engine they came with, then yes, it CAN be done. the real question is why? even with a half-bridge, you will still have too much engine for the turbos - and not just a little either, it will be a gross mismatch.

reconsider or explain what it is you're trying to do and get better advice.

 

It makes a cool sound.

Go for it!

 

Seems like PARALLEL stock twins on a half bridge would suit it ok if you are looking for ~300-350hp max.

In parallel configuration you actually get a lot of hotside area, so it shouldn't choke out the bridge on the low rpm too badly.

Downside is parallel twins are really really laggy.

I mean a stock sequential FD with exhaust/intake/IC/boost up (~300hp) would absolutely rape it.

50hp up top (and requiring supporting mods) isn't worth losing 100hp down low in my opinion.

 

basically guys this is my project, and i dont have the funds atm to do a full single turbo conversion, and i want to get my car on the road so i can drive it. reason i ask this question is just to see wheather or not i can safely run this set up. i know the factory twins are to small with comparison to the engine and its mods, but im not after big power i just want it to run so i can drive it and break the engine in.

 

thanks for the advice and info guys,keep it coming, i know it is a odd thing to do, but i do have pplans to single turbo it in the near future.

 

well, if it's pretty much just for break-in, then i don't see why it should be an issue. if you listen to Blue TII, it might even be more to your benefit because if the lag is as bad as he describes, then it pretty much guarantees you don't boost the engine while breaking it in.

 

Hey Im planning to do the same thing! Do you have a tune for power fc?

 

no sorry i dont , havnt got to that stage yet, just finishing up dropping the engine in, then will take it for a tune.

 

Oh alright. Did you delete omp, emissions etc.? If you took pictures putting back together id like to see them! Kind of unsure with some lines on mine.

 

a street port, 14 psi of boost, #9 plugs, stock twins in sequential mode, a good fuel pump, 3" exhaust and you will think twice about going single

 

^At 14 psi, the stock twins are 40 % over what MAZDA intended them. They'll be making as much heat as boost, and won't last long doing it. That's not to say you shouldn't appreciate the qualities of the stock sequential twins. You just don't need 14 psi to do it IMO.

 

no offence bro, but why do reputable Japanese rotary tuners i.e. Knightsports, re-amemiya, mines, r-magic etc produce re-mapped ecu tuned for 0.9, 1.0 and 1.1 bar of boost???
I mean taken into consideration a proper intercooler setup that would significantly reduce intake temps. I run a knightsports 4beat ecu tuned for 1.0 bar boost with a stock intercooler setup, daily driven where ambient temps are 31 degree Celsius and above with no problems been like this for some years, no turbo failure

 

No offense taken...'bro'. But just because they're well-known, Japanese, and "tuners", doesn't automatically make them reputable. They're likely just playing to the market, full of people like yourself.
You're running the stock IC but speak of running a "proper intercooler set-up"? IMO your stock IC is not "proper" for 14.5 psi (1 bar) and strongly suspect your IATs are silly high. Probably fortunately for you....with the pressure drop on the stock IC, the manifold is seeing a lot less than 14.5. Still, your stock twins are working way harder...and their life-span has been shortened.

BTW, love your island.

 

hey hey don't jump on my stock inter-heater , that's all money can afford at the moment, I usually run stock boost during the day, only with proper fuel and cooler temps I may run 1.0 bar. I agree 100% on turbos passing its efficiency levels at or above 14 psi, just testing your knowledge
I have acquired a pair of knightsports rf420 that I will install soon cost me like $53USD , but is in desperate need of a rebuild. Trinidad is a great country

 

Skip the Bridgeport. Unless you are going for higher power levels with a single turbo (500HP +) then your best bet is a street port. You'll also enjoy not getting 8MPG.

 

Did you ever run non sequential twins on a halfbridge or bridge aaron cake?

 

No, but I have run half bridgeports on other smallish turbos. It's great in the beginning because the turbo is on/off. Instant boost at any RPM. But the peak power sucks and doesn't do the Bridgeport any justice. So you're wasting all that fuel and dealing with a hard to tune engine for no benefit compared to just properly sizing the turbo.

 

Aaron what about a HBP with a Borg Warner EFR 8374?? I was originally planning on the 7670 because of the fast response but after reading your post I am having second thoughts.. Love you youtube channel btw, cheers

 

stevexk


Aaron what about a HBP with a Borg Warner EFR 8374??

I'm not Aaron, but-

Yes, this is a really really good combination.

There are several bridge and semi p-port circuit race cars in Japan that use the HKS T04Z (which is has 84mm compressor and 74mm turbine wheel major diameters).

This combo would have insane spool and do 450rwhp on low boost and up to 500rwhp on medium boost. Probably couldn't run high boost because the compressor would already be out of flow.

I would recommend lots of external wastegate (like the 60mm on the HKS T04Z) on this combo though as opposed to the popular internal wastegate and maybe even the 1.15AR exhaust housing over the usual 1.05AR one.

 

BLUE - really appreciate the info man, trying to learn as much as I can before I actually pull the trigger and get things in motion.

Hmm 450rwhp would be perfect. From what I have been gathering, the fact that a HBP would produce more exhaust would allow it to spool a larger turbo as fast as say a stock port would on a smaller turbo, but still be able to be useful in the higher rpm range. For example sake, how would you compare the response time of a stock port with an efr 7670 vs a HBP on a 8374? What rpm range would you assume the turbos would kick in at? Everyone is trying to tell me to go street port for response time and reliability etc etc.. I understand this would be more beneficial for what I am trying to achieve, but I am stubborn to wanting a half bridge, especially after reading about BDC's HBP's.

So you would suggest EWG for this settup, is it because running lower boost on efr's with an IWG would be susceptible to boost creep? I have come across a thread of someone running into boost creep problems with an IWG efr at 12 psi.. What would you suggest for injector sizing? I am planning to combo all this with a v mount and water injection as well on pump 93. I should also mention I have an apex pfc.

 

For example sake, how would you compare the response time of a stock port with an efr 7670 vs a HBP on a 8374? What rpm range would you assume the turbos would kick in at

I have no idea, but from watching videos even on a street or stock port the response of the EFR 8374 is really close to the EFR 7670 on the same port.

Sometimes when you drive a car you perceive a more of a difference though, the human body is a sensitive instrument.

I am not 100% sure what you mean by at what RPM the turbos would kick in, but on both turbos right around 3,000rpm is when the boost curve will go nearly vertical.