TheTwinTurboRX-7

Putting together my turbo 12a setup and the 2.5 inch DP for the second gen turbo I picked up is 50 bucks cheaper than the 3. Question is am I going to be happy with that? How much of a power difference would there be from a 2.5 to a 3 inch exhaust.

Also, found cheap Holley Blue 14psi pumps. I assume that should be plenty for my turbo applications, especially since I only run at 3psi pressure right now.

Thanks for listening to my rambling and helping me out.

Ben

pillage6

I think you should be okay, depending on your fuel pressure regulator.

Right now my regulator is not working right and I am out of fuel by the end of second during spirited driving.

pillage6

Awesome.

TheTwinTurboRX-7

opps double post
the regulator I am getting is a mallory rising rate regulator
goes from 3-12 psi

fatboy7

2.5" DP will be fine for a 12a I would think, especially on a stock turbo. It depends really on what you are shooting for power-wise and how much boost you are wanting to run.

pillage6

I am going to pick up the 4309 from Wells today, mine pooped out.

I think it comes with another spring that allows you to go up to 50 psi.

RotorMotorDriver

iTrader: (1)

Yeah, a 14 PSI pump should be fine man. That leaves you plenty of room for when you hit boost and the RRFPR kicks in. Theres an 11 PSI difference, but just to be safe, I would go now more than 10. No need to max out the pump, you never know how inaccurate it can get up there at maximum flow .

~T.J.

FB II

how much boost do you plan on this thing to run when it's tuned? you may need the 3" DP IMO for better boost. i dunno, when i do mine i'm using the 3". but i don't see it making allll that much difference. ok now i'm rambling

TheTwinTurboRX-7

thanks guys
I decided I will go for the 3" and a custom 3 inch exhaust
going to pick up one of the pumps later on today

FB II

YESSSSSS! Good choice! i know you'll be happy with it. hahahaha WOOOOOOOOOOO!!!!!!!!!!

RotorMotorDriver

iTrader: (1)

Makes me wanna continue my turbo project .

~T.J.

S2-13BT

I have a 2.5 inch exhaust on my 13BT and it quite happily runs 12psi and sounds good too. I do plan to go to a 3 inch exhaust when funds allow, but it's fine as it is. I guess it depends on how much boost you wanna run and what kinda power levels you're aiming for.

Also, be aware that a S4 (and possibly S5) turbo may have boost creep issues with a 3 inch exhaust due to lower back pressure. Which do you have? And are you using the stock internal wastegate or external?

TheTwinTurboRX-7

stock internal wastegate, low boost
5psi

piston pounder

Hey pillage6, what makes you think your FPR is f--ked?. Im having the same problems with running out of petro at the end of second gear also. The funny thing is this Holley POS Blue pump and FPR is almost brand new!. Any ideas anyone?

MIKE-P-28

iTrader: (1)

On mine I ran a 3 .. The whole exhaust DP and all , muffler everything was like 350 bucks I forget the exact price but 2.5 should be fine with your setup.

SoRRoW

Are you guys really sure a Holley blue is good enough for turbo?

When I was looking into turbo plans I was gonna run a Aeromotive high pressure pump.

I reall dont think its good for turbo,I might be wrong but recheck with someone who has a Turbo set up.

BTW I have a Holley blue and regulator on the car,I never had a problem.

TheTwinTurboRX-7

its more than enough pressure to overcome the low boost I am running, why wouldn't it be any good

S2-13BT

I'm wondering how you're going to achieve this. The stock boost for S4 and S5 is around 6-7psi. There is no way to lower boost unless you fit a larger wastegate or introduce more back pressure. I can only see you getting more than 8psi with a 2.5 inch exhaust that's any decent. And even more with a 3 inch.

Is the turbo S4 or S5? you can tell because the S4 has a single wastegate door and the S5 has dual doors. The S5 can therefore control boost better.

Am I missing something here?

pillage6

I talked to a few people and they said when a fuel pump goes bad, it just quits, so I figured my regulator was bad.

I just replaced the filter not long ago, so I know that isn't clogged. I checked the vacuum line from the plenum to the regualtor, that isn't clogged.

Last night I bought a new gauge, sometimes it reads 4-5 lbs. and sometimes 1 lb.. My fuel trouble is getting worse, now I am running out of gas during regular driving sometimes.

TheTwinTurboRX-7

it is a series four
already know that
spent more time on the second gen than the first, but thanks for the tip
port the wastegate, run a maunal boost controller

Felix Wankel

You won't need a boost controller at all to run 5 psi. A boost controller isn't going to turn the boost down any lower than what the wastegate actuator is set for. I think its like 5.5-6 psi on a S4, so good luck.

fatboy7

I think both the S4 and S5 wastegate actuators are both set to 5.5 psi, so you won't beable to go lower than this unless you get a different actuator. IIRC the S5 runs higher boost with help from a built in EBC that is suppose to keep the boost to 8psi.

Both S4 and S5 have creep problems with an open exhaust. For instance RB's full exhaust (3" until the y-pipe) on the TII claims to raise the boost to about 10-12 psi. This is due to boost creep, which is not good.

Simply put, boost creep means that your turbo system is out of control, which is dangerous and not optimal in any way.

Port those baby wastegates, then you can use the manual boost controller to turn up the boost when you feel like you are ready for it.

680RWHP12A

PLEASE LISTEN TO ME!!!!! the holley blue will not work for turbo!!!!! stop blaming the FMU!! the only way for a FMU to fail is for the diaphram to crack, or rupture, not raising the fuel pressure, a simple way to test your fmu is remove the boost sensing line, and turn on the fuel pump,if the FMU is bad it will leak gas!

you need a high pressure EFI style pump in order to have a blowthrough system that works properly, THATS THE BOTTOM LINE!!!!

RotorMotorDriver

iTrader: (1)

You know, I didnt think the blue would work, I mean its like 110 GPH which is a lot of gas, but no pressure. Its a high volume pump, not high pressure. Youre gonna need high pressure and a decently high volume as well. I was going to use a stock GSL-SE fuel pump for my setup.

~T.J.

pillage6

I just bought the GSL-SE pump for my blow through, I took Robert's advice.

After this weekend, I will let you know what happens. Right now I am running out of fuel at the end of second gear WOT.