T25... spools to 15psi at 4000?

[curt2go]

Wel I have posted a few other places about this but here is the problem. I hit full boost on a t25 at about 4000 rpms.. That is bad.. It is very sluggish of the line. I mean very sluggish. Compression on average is 158. Tiny boost leak at the TB shaft but still getting the bubbling in the oil on the turblo inlet boost leak test.

I did recently port the t25 mani and o2 sensor housing....

I even blocked of the pcv and same result(It leaks a tiny bit as wee. The new one I bought leaks even more)

Please help.... This now is starting to get madening. i have been chassing little boost leaks but none of them are the culprit. They are all fixed now except for the tb shaft. The boost leak test will get to 20 psi but then slowly go down to 5 psi and stay. Slowlyt meaning about 20 secs to get from 20psi to 5.

Let me know what you guys think. Thanx

 

[ddavisaf]

15lbs of boost with stock exhaust is fine. At least, I think that's what you're saying when you said DP. I ran it all day long.

 

[curt2go]

I don't have a down pipe but will be getting one soon and do have a boost gauge. Along with full exhaust. I will be pulling my own 02 sensor numbers along with what the reading is at the rpm and such. Making my own little device to log this on a computer soon.So I will no the a/f of the car. I have done the basic maintenance to the car. the only thing that has not gotten looked at is the trani. But the fluid is not dark and is at a good level. I am going to order TB gaskets and seals and mani gaskets todays. Where is the best to get those.. Keep in mind I am in Canada so I will have to order then online most likely.. TTY

 

[ddavisaf]

Mach V

Jackson Auto Machine May have them... not sure.

DS Motorsports Call and talk to someone to order.

DSS Call and talk to someone to order.

Slow Boy Racing Probably have to talk to someone here too.

 

[curt2go]

Thanx..

 

[doug]

A guy on the DSMLink forums (actually he's the guy that developed the Palm Pilot client for DSMLink), Hal Landry, does throttle body rebuilds-- I just had him do mine and he did a great job. If you have the time and don't feel like doing it yourself, I highly recommend his services.

http://206.124.12.138/hlfab/index.html

 

[91Bomb]

15lbs of boost with stock exhaust is fine. At least, I think that's what you're saying when you said DP. I ran it all day long.

My understanding has always been that the stock downpipes (DP) on our cars are very restrictive because of the 90 degree press-bent section (2" inner diameter on straight sections and much less on bends) AND because the flex section of the DP is restrictive (not 100% sure about flex-section being restrictive because I heard this from a meineke guy)

Of course the stock cat converter adds a great deal of restiction too. From what I've read in the past the stock mufflers aren't too bad. If you only remove the cat you will reduce restriction in the system but not enough IMO for running 15 lbs. Personally I'd have a DP + hgh-flow cat (or test pipe) before upping the boost.

You might not notice a problem right now but trying to force too much exhaust through pipes too small is going to cause your engine and turbo to work harder and as a result excess pressure inside the engine

Stock DP + added boost =

 

[Attack Eagle]

My understanding has always been that the stock downpipes (DP) on our cars are very restrictive because of the 90 degree press-bent section (2" inner diameter on straight sections and much less on bends) AND because the flex section of the DP is restrictive (not 100% sure about flex-section being restrictive because I heard this from a meineke guy)

Of course the stock cat converter adds a great deal of restiction too. From what I've read in the past the stock mufflers aren't too bad. If you only remove the cat you will reduce restriction in the system but not enough IMO for running 15 lbs. Personally I'd have a DP + hgh-flow cat (or test pipe) before upping the boost.

You might not notice a problem right now but trying to force too much exhaust through pipes too small is going to cause your engine and turbo to work harder and as a result excess pressure inside the engine

Stock DP + added boost =

hi, this is a 97 turbo, not an n/a 1g.

The dp is one of the things you do after you have gone to a bigger turbo. on a t25 it flows more than enough with just a cat back without spiking (15-16psi until 5k). If you have the inclination you can swpa to a 3 inch dp and cat and but then you start running into overrun spikes of 19 psi until it settles at 15-16 before falling off.

 

[91Bomb]

hi, this is a 97 turbo, not an n/a 1g.

What does a n/a 1g have to do with anything

 

[curt2go]

I am ordering the downpipe tommorow and I will let you all know what the outcome is. It may not be as big a difference with a t25 but with a 14b i think you would definately need the more breathing.. TTY

 

[doug]

It will help a little, but my feeling is that's not your main problem. I hope I'm wrong, though-- I know this is pretty frustrating for you.

 

[curt2go]

I know that it is not my problem but ai wanted to get a downpiep anyways.. It will help alot with the 14b.. TTY

 

[ddavisaf]

I ran 16psi on a 14b with stock exhaust also

I have never had a problem with excessive crankcase pressure.

Every oil change involves me check the pcv though. I run stock locations on the pcv and valve cover vent.
Regular maintenace is pretty good for your car, contrary to popular belief.

 

[91Bomb]

I ran 16psi on a 14b with stock exhaust also

I have never had a problem with excessive crankcase pressure.

How are you monitoring it?


I have a real problem with what is left out in 'upgrade path 0' and how new DSM'ers can get pretty fouled up IMO by following it. Since 'upgrade path 1' is for 275+ HP it will be assumed that path 0 is for stock HP up to 275 HP.

I listed earlier in this thread what I thought to be wise to have when going the 'cheap upgrade' route which would be the route where you are running stock injectors, FP, turbo, etc.

To me the 'cheap upgrade' path means you want to run the max boost with theese stock components and not lean out which is at about 16 lbs.

Since those who choose this route probably aren't using a 'logger' I would pesonally recomend the following that are not listed in 'upgrade path 0':

EGT or wideband o2 -- so some basic monitoring can be done
Real boost gauge -- the stock one is good for stock boost only
Run 15 lbs boost -- If you run 16 which everyone says is the max and your boost gauge is off..
FP re-wire

A couple of things I see under 'upgrade path 0' that I personally don't think is nearly as critical or even necessary for this 'cheap upgrade'/15 lbs boost path is:

Hacked maf
Removal of ridge in TB elbow
BCS mod ( get a bleeder valve if you don't have an mbc)

There's some debate whether stock exhaust is good for 15-16 lbs. I'd AT LEAST have a test pipe on there if all else is remaining stock. If I wanted to be environmentaly freindly and/or liked to go for state emmisions testing I'd get the high-flow cat but would them definately go to at least a 2-3/8" DP.

Maybe in between upgrade path 0 + 1 there should be the 'cheap upgrade' path for some of the reasons I just mentioned.

BTW, my profile says 1g N/T but I owned a 1g turbo for 8 yrs and I'm shoping for another one and the 'cheap upgrade' path is my preferred route because it's cheap