How much psi is the 2G uip good for?

[truwarrior]

I was thinking about just getting a EVO BOV if it fits on my 2G. Thing is how much psi can a stock uip flow? I don't wanna be pushing 20 psi and only getting 16 psi up to the throttle body. Then I could put the money saved towards a greddy FMIC and T28

 

[mlopez]

Huh

 

[Mistaspakles]

UIP? 1 zillion psi.

 

[jpolizo]

There are two problems with the stock UIP assembly. One is the stock BOV which leaks boost. The second is that the pipe itself is a weirdly flattened thing that seriously harms air flow. Replacing the BOV will help you hold boost pressure, but you still won't be able to get much air through the pipe. Do both for best results.

 

[nhsean69]

If it helps, i did a leak test and i had everything pressureized to about 17-18psi, stock pipes seemed to be fine. Just make sure all the clamps are tight. Doesnt mean, you shouldnt upgrade them tho. I recently went to the Greddy Pipes.

 

[truwarrior]

Does anyone know what I'm talking about? I'm trying to figure air flow and pressure at the two different sided before and after the bend.

 

[truwarrior]

Basically if I'm running 18 psi into the throttle body, what's my boost in the lower intercooler pipes? Ig it's less then .5 psi I'm not to worried about it.

 

[KRAZYKOREAN]

Your making the same boost level everywhere...lower and upper piping...etc etc..its all the same pressure..also your not makinbg any sense..

 

[truwarrior]

No it makes perfect sence. You basically said it's worthless to get a uip because the stock uip and lower ic would have the same psi hense making the purchases of a uip pointless to me anyways . Although I don't think you know what I'm talking about and I don't know what your talking about.

Let try this again.

If I'm making a 20 psi after the turbo outlet how much would the bend in the uip decrease flow and reduce boost by redline? Basically I don't wanna overboost my turbo just to get the desired boost level to the throttle body.

Well I guess I figured out a way to test it. Just set the boost in low rpms then when I redline if the boost drops my uip is probably the bottle neck of flow, of course I'll need a new turbo first

 

[Gopherhog]

Your biggest drop in boost post-turbo is most likely going to be in your intercooler, unless you have some serious knots in your piping. Flow wise, i don't think you are loosing any PSI, but you are definitely not flowing as many CFM as you could be.

Is that what you are asking?

 

[jpolizo]

I think I see what you are talking about. If I connect a 2000psi scuba tank compressor to an open 55 gallon drum with a hypodermic needle, you will see a couple thousand psi on the compressor side, and practically nothing in the drum. You are trying to figure inability to flow air volume as pressure drop across a restriction. An interesting excercise and if you run some experiments it will be interesting to see what you come up with.

On the other hand, if you dig around on the Internet you will find many, many, upgrade guides for the turbo DSM cars. I haven't seen one yet that hasn't determined the UIP to be a restriction worthy of repair. These upgrade guides were done by folks who tried lots of things and wrote down what worked. If you think they are all wrong and test this yourself, you would be doing everyone a service by posting your results.

Personally, I can't imagine the stock pipe flowing air for beans and I did notice an improvement in my car's performance when I replaced the pipe. Maybe that's just wishful thinking on my part though.

 

[jpolizo]

In thinking about this some more, I think I figured out what your original question was. Paraphrased: "how much do I need to turn up boost to compensate for not replacing the UIP"? Or, another way: "is 15psi with the stock pipe the same as 14psi (or whatever) with an upgraded pipe"?

You can do lots of things to your car that will increase performance, other than the UIP. Certainly going with a turbo and intercooler will make you very happy even if you don't do the UIP. The whole intake, engine, and exhaust is a system and, depending on your goals and your budget, numerous combinations of upgrades may get you where you want to be.

The UIP is not an absolute limit. Yes, you can compensate in other ways and, were I to guess, I'd say 1psi would pretty well cover it in a moderately upgraded car.

 

[truwarrior]

Bingo. The only way I can think to test this is to put a boost gauge right after the turbo and then one coming from the throttle body, make a run then compare the boost pressures at different rpms.

I figured the stock uip is some what of a restriction but just how much? Is it really better replacing a nice light weight pipe with a heavy metal one that cost $$$. The pipe I do want is $300 with 1G bov. If I could just use a EVO BOV then I could put that money to use on something else.

 

[jpolizo]

Sounds like your experiment would work, but it also sounds like a heckuva lot of work. I'm also not sure if the results scale well. For example, would you get the same answer with a T-25 as you would with an FP Green at the same boost level? The Green would be trying to move a lot more air through the restricted pipe.

You might be able to infer the answer. Buschur indicates that an upgraded UIP is something like 7-10 horsepower gain. I'm not sure what to figure for a psi-to-horsepower conversion factor but if you could find a reasonable one for the target turbo, that might get you the answer you want.

 

[mlopez]

Originally posted by truwarrior
Bingo. The only way I can think to test this is to put a boost gauge right after the turbo and then one coming from the throttle body, make a run then compare the boost pressures at different rpms.

I figured the stock uip is some what of a restriction but just how much? Is it really better replacing a nice light weight pipe with a heavy metal one that cost $$$. The pipe I do want is $300 with 1G bov. If I could just use a EVO BOV then I could put that money to use on something else.

Why go through all the trouble. If you don't want to spend the money on a name brand uip, then just have one made out of aluminum from a local shop. The uip seems to be a real restrictor. Just follow the upgrade path in order.

 

[Omega]

You are confusing boost (pressure)with airflow.

No matter how small or large a pipe is, it will always hold the same amount of pressure (boost). Now, a small dia pipe can flow as much air as a large diameter pipe, but it will need a higher pressure to do so... which is what I think you are trying to say.

By upgrading the UICP you are increasing airflow. Now, by increasing the amount of airflow into the engine, you will actually lower the pressure of the intake. You will actually be making more HP, but at a lower pressure (less boost)

 

[jim97gst]

A Brode UICP is about $65. A used 1G BOV is ~$50. So for a little over a $100 you can make what most people seem to think is a huge improvement (measuring with a butt dyno). My wife said she could feel the improvement, and she normally has no interest in what I'm doing to the car. I don't think you'll find a better bang for the buck improvement.

 

[kpt4321]

Omega is right on the money.

The UICP is "good for" as much pressure as you want to throw at it.

What you're concerned with is the pressure DROP of the intake piping. You will find that there is approximately a 1-2 psi drop in pressure from the turbo outlet to the TB, with stock everything. The intercooler accounts for the vast majority of this.

Upgrading the UICP only will probably not net you much more manifold pressure for the same turbo outlet pressure. It will, however, net you more flow, and therefore more power.

If you're concerned with pressure drop, get a new intercooler.

....Kyle T.
93 TSi AWD "TURBO4"
14b - 12.8 @ 108

 

[swedeGSX]

You can make your own uicp just cut the flat part of and put a sturdy hose or a metal bend there instead. That's a cheap fix. Make sure you glue on some typ of beading on the plastic pipe or use 2 or more hose clamps so it doesn't fly of.

 

[GoSpeedRacerGo]

Remember you are going to custom fab at least SOME piping if you want to get a t28 and FMIC...so why not just go all out and get some short route piping? Someone local could make all your piping for less than 75 bux...

 

[igs]

theres a difference between pressure and flow. pressure is the same EVERYWHERE. pressure is limited by how strong your pipes and clamps are. flow is the same EVERYWHERE. flow is limited by the biggest restriction in your intake path. Get it?