Car just has hacked airbox w/ K&N dropin and downpipe, stock maincat/catback

 

more information please.......


what your boost pattern....more detailed.

 

10-11 psi on the primary, spike to 11-12 psi at transition, solid 10.5-10.0 on the seconary, then falling to 9.0-9.5 by 6500 and 8.0-8.5psi @ 7000

 

i have somewhat of a similiar problem.. my boost pattern is 10-6- 11/12 at transition then 7 psi.. im still trying to find out the issue. The general opinion is a clogged cat.

 

yep. clogged or clogging cat. remove the 2 bolts to the downpipe and shine a light in there to have a look. if it looks like clean fine mesh, all is good. if it looks like a hair clogged shower drain, it's melting/melted.

 

That's about right. With a mostly stock car, it usually won't be able to hold more than 8-9 PSI to redline:

http://www.scuderiaciriani.com/rx7/boost_test.html

 

I agree with Mahjik - my stock 94 with 38,000 miles had a similar boost curve after I installed a downpipe: 11.5 psi on primary, spike to 11 after transition, then 9.5 psi to 6.5K and 8.5 psi at 7K.

I'm playing around with larger restrictor pills in the wastegate actuator hose in order to lower the spike at 5.5K because it causes boost cut in cold weather. I'm running a Holley 72 jet now and problem is much better, with no drop in boost above 6K.

 

Is a catback going to let me have 10 to redline?

 

Adding a catback to your current mods should make it able to hold 10 PSI to redline.

 

See my mods to Intake and Exhuast are Apexi Twin intake's. And 3 inch DP and 3inch CB with RB Dual Tip. SO im suspecting my cat is the issue.