I have a rx7 fd 1995 and am thinking of adding more power. The two ways I am looking to start adding power is Bridgeport the engine or to add a bigger turbo. I am running 10psi with both turbos and am thinking off making the second turbo run more boost. What is the better option to start with. I will be doing both eventually but what is best to start with? Cheers

 

Take your pick..they will both start you on a financial journey..as you start altering the engine or any parts,you need other supporting parts to make that modification work properly.

 

Whats your power goal first?

 

First question is what's your use of the car? Daily driver, street car, weekend track car? If the majority is street driving then stick with a street port and a larger turbo and more boost. You will have more usable power through the rpm range with a streetport and a turbo to match your use of the car. If it's mainly a track car and you don't drive it that much on the streets then sure go bridgerport or even semiPport.

 

somewhere around 400hp to the wheels. or as close to it as i can get

 

Look into the EFR 8374 or a similar sized turbo. With upgraded fuel and spark you'll be able to make 400hp. There is an older thread from Turblown that made 483 with e85 and stock ports.

 

I second Brian's recommendation of the Borg Warner EFR 8374 setup, and would also recommend Turblown's own street setup kit with the TDX61 with a 1.0 A/R spec. I would imagine with a street spec aiming for 400whp, you would want a good balance between air flow at high rpm and low down response / spool up. The EFR has great response even with the boost set relatively low 1-1.2 bar for example, and Garrett TO4's / GT35 series have similar specs and hold boost well up to the redline.

You would want to street port the motor if you are trying to improve overall air flow and efficiency through other complementing upgrades such as open exhaust / intake, bigger and smoother flowing intake track pre/post intercooler. You can take that even further with bigger throttle bodies, port match both the UIM and LIM or get one of Elite Rotary's awesome intake kit package. Stock ports are not inferior in anyway if you aren't staying in the 7500 - 8000 rpm range 80% + of the time because your peak power is around that area, in the case of Bridge ported motors.

If you do go the single turbo route, you will also have to upgrade the fuel system so replacing the stock rails and injectors to more modern top feed set up with bigger injectors. More high flow fuel pump hot wired will keep injector duty at safe levels and widen scope for turning up boost if you want. This will allow you to tune the new turbo setup to its most useable power band and get you into the max power zone as often as possible during street driving.

 

if i get and EFR 8374 will i need to rebuild the engine with new seals, dowls and ports? their websites says it can produce 5-800hp

 

If you want to make the upper limit of the turbos potential then yes, at 400 then no.

 

would it be better to get a medium sized turbo? not a large one like the EFR 8374. mate of mine says thats to big for the car and will have huge lag

 

8374 is perfect size for 400-500rwhp rotary - basically premium pump fuel/15-16 psi type of deal. VERY responsive.
It can be pushed to maybe 550, but you'd want E85 or water/meth inj for that.
The next smallest one is the 7670 which also works well but with stupid response and will need more boost to make less power up top.
The 800hp rating is theoretical figure for a piston engine measured at flywheel.

 

The EFR 8374 is the single turbo you want for your goals.

On a rotary it is sized to make 350-550rwhp (low boost stock port to maxing the turbo on a big port rotary).

It is very responsive-
Check out this video of an FD on a track with EFR 8374 (boost gauge is on the Left on dash).

I used an EFR 7670 on my FC which has twitchy boost response, but it is sized for 250-450rwhp on a rotary.

 

Going the single turbo route, couldn't you just get bigger injectors and use the stock rails? pros/cons? Also, I think ECU upgrade either way (I didn't note if he did that already). I'm also guessing the fuel upgrade includes the pump and FPR.

 

The OE rail wouldn't be able to accept any modern injectors and the old injectors are quite outdated. Depending on power goals you can get away with upgrading the secondary rail and keeping the primary rail as is. Full Function Engineering sells just that too.

 

When it comes to fuel rails, there are so many choices out there to choose. I am sure some of the official vendors on this forum can chime in on this. Depending on the lower intake manifold you use (OEM or aftermarket like eXcessive or Elite) you can also choose to blank out the primary fuel rail opening on the iron and use a single four injector top feed rail directly on the manifold. Makes for a simpler and cleaner injector setup. If using the OEM manifold then obviously get a both secondary and primary injector rails to accept modern injectors.

 

back to life!!

Any comments on modern turbos? Everyone and their mom says that turbo technology has come leaps and bounds in the past few years... there's gotta be a good solution for the FD!
I've heard great things about the Garrett GTX series, and the new Borg Warners, but would love some help narrowing down the exact models!

I'm looking for:
Streetability (relatively low rev boost)
Reliability (easier/better maintenance over stock)
Stock+ power (say 350hp at wheels)

Happy to do cooling upgrades to support it; i.e. second oil cooler, V-mount rad/IC kit.

Car is a '99 RB (265hp, single oil cooler.)

Any help appreciated!!

 

Nothing compares to the EFR on a rotary because the lighter TitaniumAluminide exhaust wheel is like a leaf in the wind to the rotary's strong exhaust pulse.

If you are sure you only want 350rwhp and best possible spool an efr7670 is the turbo. If you think you might want more than 400rwhp ever but not over 550rwhp the efr8374 is the turbo.

If you wait and get the turbosource variable ar version of the efr8374 exhaust housing you will have the latest/best technology turbo for the rotary (not sure it is out yet).

 

Not done yet, wish it was

 

Thanks again! I've never heard anyone ask if I "only" wanted 350 at the wheels lol
On an efr8374, at what RPM would it be fully spooled? what about the smaller efr7670?

 

Fully spooled? I guess it depends on how much boost you want to run.

Example, depending on gear/load my EFR 7670 could only do 14psi or so at 3,000rpm, but could hit my target 26psi by 3,500rpm.

8374 is going to be about the same depending on set-up (manifold, port, size of downpipe), however the bigger 8374 compressor tends to surge if you try for example to run that same 26psi at 3,500rpm so you might have to slow the boost ramp down so its more like 17-20psi between 3-3,500rpm and full boost at 4,000rpm.

If you are shooting for low boost and 400rwhp you should see that right between 3,000 and 3,500rpm depending on the rest of the set-up on either turbo. Difference is the EFR 7670 will be a hair more responsive.

 

We have several vidoes on our youtube channel.

Generally the 8374 sees 15 psi by 3k for most people( capable of 25 psi at this RPM)
The 7670 sees 15 psi by 2700rpms( capable of 30 psi by 3k rpm).

4th gear figures, bigger difference in the lower gears.

https://www.youtube.com/user/TurblownEng/videos

 

Bridge and single

 

Recommend Bridgeport with medium turbo. So fun to drive and with a smaller lag.