dyno claimed 8.5psi???

[g2ic02]

alright i have a redtop sr20det with a t28 set at stock boost.... ok i have a couple of questions....why is it boosting to 8.5 psi i thought stock boost on a s15 t28 was 10psi...i have also heard 7psi....but why the odd number from a mustang dyno. The kid i bought it from said it only had 18,000 miles on the turbo so it shouldn't have a bad wastegate actuator.

If someone could also clear up, whether all s15 t28's are ball bearing would be great, because it takes longer to hit full boost than my t25..

Oh i hit 189 rwhp/174tq on the mustang dyno at like 65 degrees @stock boost(walbro 255, fmic, 3" turbo back exhaust)

after thinking about it, maybe my fmic is robbing some pressure??

[sr240mike]

Did you get an a/f readout with that. It could be poosible that you have a boost leak.

[Flybert]

Plain and simple, get a boost gauge.

[g2ic02]

i do have a boost guage it reads 10psi...but the dyno read 8.5 at peak boost......and no they didn't hook up the wideband on my car for some reason....it was a group deal 45 for 2 pulls, so i wasn't gonna be too picky.

[Jeff240sx]

Dynos don't read boost. That's your problem.
-Jeff

[WeldingHank]

there are some dyno's that have a boost input just as a reference point for HP numbers and where you spool and such.

[g2ic02]

yup this one definetly did have a place to read boost...they tapped into the vacuum line going into my bov. are these decent numbers for stock boost on t28??

[Happyman]

yup this one definetly did have a place to read boost...they tapped into the vacuum line going into my bov. are these decent numbers for stock boost on t28??


Is your BOV before or after the intercooler and how is your boost gauge setup? Before or after the intercooler for pressure? That could be the reason. Maybe your boost gauge is setup before the IC(reading higher pressure) and the dyno was after the IC(reading the lower pressure drop that the IC causes)

[g2ic02]

my bov is before my intercooler and my boost guage is after(at the throttle body)...but i think my boost guage is off a little(junk autometer guage).....right now i have my waste gate vacuum going to my hot pipe so i am gonna try and t it off the vacuum line that goes to the bov then see what it does.

[Jeff240sx]

yup this one definetly did have a place to read boost...they tapped into the vacuum line going into my bov. are these decent numbers for stock boost on t28??

Tapping your vacuum line would mean that you a) have a vacuum leak somewhere and b) lost vacuum to something that needed it during the dyno.
I know that some Mustang dynos have a messed up left Y-axis set to boost pressure (psi), while the top line (with hp/tq) states an input boost level. Those numbers I've seen have never coincided.
-Jeff

[g2ic02]

jeff240sx .... thanks for the info on the dyno itself.....the way i had my vacuum lines hooked up on the dyno were as follows.....from from wastegate to hotpipe.......from throttle body to "t", then one end of "t" goes to bov, the other end of "t" goes to dyno so everything should have been connected correctly