[SR] Boosting until redline

[reccakun08]

Asking everyone with a sr20det with stock t25 turbo boosting over stock how much boost can it hold to until redline?

Currently i am boostin about 12psi on a mbc. It will not hold the 12psi all the way to redline it will drop all the way down to 7psi i think after 5,500rpm. I tried cranking boost to 14psi and it is still dropping. I know the stock t25 does start losing boost to redline but how much?

My friends car holds 12psi all the way to redline.

Boost leak? exhaust leak?
Car drives fine and idles fine. Just doesnt pull hard up top from the decreasing boost. Full exhaust and fmic.

Thanks.

[Def]

Mine held about 11.5 psi to redline, and it was in great condition when I took it off. Could have probably held a bit more with an EBC, as I just had a cheap MBC at the time.

[fliprayzin240sx]

Get an AVC-R, nuff said...

[tha240star]

i have a turbo xs mbc and it holds 13 to redline, its spike a lil at first to like 14-15 but thats about it

[SoSideways]

I have a Turbo XS dual stage MBC, and it can only hold about 8psi to redline. At the time of the dyno graph, I had it set at 14psi.

http://i42.photobucket.com/albums/e346/SoSideways/4-28-07_dyno_day_smaller.jpg

[s15specR]

I got a new in box AVC-R for sale, hit me up if you need it, will let it go for the low

[reccakun08]

i have Turbo XS dual stage MBC. You think thats the reason im not able to hold boost? Sosideways my graph is similar to yours. Gotta find it.


s15specR pm a 'low' price shipped.

Thanks.

[garbury]

I made my own mbc and it hit 15 psi and dropped gradually to 12 by redline. http://www.geocities.com/chmwatson/FAQs/mbc.html I threw on my ebc with the stock t25 and it would still drop down by redline. The t25 turbo has problems holding boost levels that high, unless an avcr is really that legit.

Honestly, besides the ability to change boost on the fly, I'd prefer the $12 hardware store boost controller over my greddy profec type-s.

[!Zar!]

The stock wastegate on a t25 freaks out once you start trying to raise the boost.

Also, I hope you aren't trying to boost your car that high with stock sr and no management.

haha.

[reccakun08]

yeah i thought about trying the hks actuator to see if does indeed help and guess prove the mbc isnt reliable.

[Def]

The stock wastegate on a t25 freaks out once you start trying to raise the boost.

Also, I hope you aren't trying to boost your car that high with stock sr and no management.

haha.

14-15 psi on a stock T25 with a stock ECU/injectors/MAF is just fine. The AFR curve is as jacked as it is on stock boost(lean in the midrange), but it's fine for the most part, especially street driving.

I recommend a FMIC to keep IATs down, as it doesn't take long for the SMIC to give up the ghost when trying to cool a little hairdryer like a cranked up T25.

[reccakun08]

Would an exhaust leak or a boost leak be a probable cause?

[ILoveJDM]

Would an exhaust leak or a boost leak be a probable cause?

could be

its possible one of your lines are backing off during boost.

i was having the same problem, so i reclamped and ziptied all my vaccum lines that i had been around (recent install of avc-r)

[SoSideways]

If you're worried about a leak, get yourself a pressure tester, hook it up to where your MAF would be, and pressurize the system to like 20psi.

You will find your leaks much better with that method, if you have any leaks at all.

[codyille]

I've seen this problem with homemade boost controllers. Try a higher quality controller. Or different vac line?