Billiumss

iTrader: (11)

Hello,

What's an affordable way to test your turbo back pressure? Are their decent kits on the market? Analog, digital? What are you using?

From my understanding you want a 1:1 ratio, At what point do you have to start worrying about too much back pressure? 2:1?

Could I use my Narrow Band O2 bung as a port to do some quick tests from?

Thanks!

3 window

iTrader: (1)

Sure you could use the narrow band bung. 1:1 is great while at around 2:1 you’ll see diminishing returns when the boost is turned up. I’ve heard of guys using a cheap peak and hold tire pressure gauge as a super budget route. I use a transducer tapped into the turbine housing right at the flange and monitor it through the ecu. Hope this helps, good luck.

gametech

iTrader: (1)

You only worry about too much backpressure if your power is too low or your exhaust is melting. Less than 1/1 is ideal, but it never has happened on a street legal car, and sometimes not even on race cars. You aim for a certain power or torque goal, then build around it. Backpressure is at the other end of the = sign.

C5_Pete

iTrader: (8)

I’ll preface this with…. I have a race car, not a street car.

It’s nice to measure back pressure and log it. as it gets toward 2:1, you can open the waste gate to relieve the pressure and keep everything in its “happy place”.

As for street car, I’d think just something like upthread with a peak/hold pressure gauge on the dyno (or for a street pull for that matter) to get an idea if your setup is as efficient as it should be.

Good luck

The BallSS

iTrader: (9)

If you're running a 7875 turbo on an LS2 then you're guaranteed to run into excessive back pressure sooner or later.
My 7875 on my LS1 started running out of breath around 6,500 rpm so an LS2 will just get there quicker.
If you can get a reading on the cheap then go for it, otherwise I wouldn't worry about it, you'll see power plateau when it becomes a problem.

SLOW SEDAN

iTrader: (13)

The cheap (~$25) sensors that work with Holley for fuel and oil pressure also work for back pressure. Weld a bung to exhaust, run some coiled hardline to insulate it, configure it, away you go.

The BallSS

iTrader: (9)

Stupid question, you wouldn't happen to have a picture of what this looks like would you?

SLOW SEDAN

iTrader: (13)

You can do it like this:



or a bit fancier with a kit like this: Earls PK0001ERL Earls Exhaust Back Pressure Plumbing Kit (holley.com)

The BallSS

iTrader: (9)

Ah I see, I assumed that's how it went but you know what they say about assumptions lol.
Thank you sir!

pdxmotorhead

A map sensor would measure that wouldn't it? I got to thinking U-pullit..

ddnspider

iTrader: (26)

The plastic sensor will melt unless you do the cool like SS suggested. Not to mention you'd want a 2 bar sensor. The cheap transducers have a nice easy transfer function too for logging.

SLOW SEDAN

iTrader: (13)

100 PSI stainless sensor is only $20 not even worth messing with a POS plastic one.

tblentrprz

Anyone monitoring dome pressure vs exhaust back pressure?

C5_Pete

iTrader: (8)

absolutely. Gotta have a reference.

Dome pressure
Boost pressure
Back pressure

Log them all and see how efficient (or not) your system is.

Billiumss

iTrader: (11)

Thanks for the insight guys. With the $20 sensor, how could I read the value?

Could I integrate the output signal into my HP Tuners Pro interface?

What the heck is Dome Pressure?

I have the Huron Speed T4 AC Kit. For Turbo, I have the Turbonetics 7575 Billet with a 1.15AR housing.

wannafbody

iTrader: (2)

Hold your hand against the end of the downpipe.

ddnspider

iTrader: (26)

HPT pro or EGR pintle position.

SLOW SEDAN

iTrader: (13)

There isnt any dome pressure on your average 7-8 second street car that only uses the bottom port.


Yess!!

customblackbird

iTrader: (2)

I’m getting ready to log back pressure with my new 70/70 turbo. I’m going with the low dollar motorsports $50 100psi transducer which is recommended over the generic $20-35 100psi transducer beloved to have more accurate reading with less noise. Then got a $12 copper tubing mechanical gauge install kit. That’s all you need. I got a 15ft harness and I’m gona pull the oil pressure and connect in on my Holley term x and I will be able to log back pressure with a run and also see how it correlates with boost etc. I could set it up as a input but not worth it as it’s just for testing and then will remove. I’m also gona run boost, pre turbo back pressure and after turbo to see how much I’m seeing in the down pipe and how that relates to the pre turbo pressure. Less than $100 but that’s with the term x ECM. My HP tuners I got the logging external connector where I can add external inputs and it worked for a WB02 I ran when I used HP tuners.

tblentrprz

How close is dome pressure compared to back pressure?