I have a civic d16z6 with a Precision 55mm Turbo 3231 T3/T4 490hp 4-Bolt .63 A/R, and the problem is that i can't load more to 13 psi and turn to 7500 rpm not before, the psi load so slow i can't not get the boost i want what is of 18 psi at 5500 rpm.
some mechanics tell me what put a .ar48 in exhaust and this solve the problem, but i donīt think in the idea because my proyect I'm putting together for 350+hp at 20+psi

my setup is this:

Turbocharger: http://www.ebay.com/itm/Precision-55...#ht_4930wt_753

vitara pistons (75.5mm)
eagle rods
head stock d16z6 (ported)
arps
injectors 510cc
walbro pump 225
wideband innovate
ecu demon (ectune)
blow off greddy
wastegate 38mm emusa
downpipe 3"

1. believe that the Turbocharger is too big for my engine?
2. which could be the problem?

thanks

 

HELP!!!!!

 

The turbo you have will work well for your engine. There must be another reason for the boosting issue. Have you checked the intercooler piping for leaks? If a coupler is loose, it could leak air faster than the turbo can replace it...which means you build some boost, but not much.

What spring is in the wastegate?
Are you using a boost controller? If so, which one?
Which exhaust manifold are you using?
Do you have an upgraded MAP sensor?

*You may consider a larger set of injectors. I would recommend 550cc+

 

Map sensor or boost controller. I have a bigger snail and boost 21 pounds no problem. reaches full boost at about 5500 rpm

 

Are you sure your vtec is engaging? I have built several sohc turbos. They all start spooling with this turbo at about 4500 or a little less and full boost buy 5500 or near that. When I said full boost I meant 25psi+. You either have a boost leak or no vtec or your timimg is way off! Even if this low comp build with Vitaras, it should still have no trouble. Hopefully this helps!