yeah man, this makes no sense at all. so you have a boost gauge reading off the mani, and the map sensor and they both say 10-11. very weird. i mean stock exhaust had me about 1psi higher, but your way higher.

def get it on the dyno. make sure the crank pullley is correct dia too. i know it sounds weird, but if that was wrong dia, then everything else would spin differently. worth a check. stock oem crank pulley is about 139mm. worth a check cuase this would also influence boost. good luck and get that beast dyno'd.

 

What sort of boost gauge are you using? I've seen 2-3 psi difference between various gauges and sensors.

Tim

 

dual sensors


OEM MAP sensor and a Zeitronix MAP

 

With the OEM MAP sensor I can only see when logging data on my laptop. The boost gage is Zeitronix (with Kavlico sensor) and it has a peak hold feature so I can check peak boost any time I want. The Zeitronix boost gage and Kavlico boost sensor are sold together by Zeitronix so they are calibrated for each other.

I have made a bunch of logging runs where I compared the OEM MAP logged results to the peak on the Zeitronix. They have always been within 0.3 psi of each other. The OEM MAP boost graphs were originally very erratic until I replumbed the line to the sensor which smoothed the graphs dramatically.

When I first got the SOT kit I only had the OEM MAP sensor. My first boosted runs logged higher boost than expected so I assumed the OEM MAP sensor was miscalibrated at positive boost pressures. Later I got the Zeitronix boost gage/sensor but it gave the same boost results as the OEM MAP. I have always been surprised at how close the two boost sensors compare to each other.

Both sensors tap in at the same point at the dummy throttle body just before the intake mainfold.

 

Just to resurrect this thread, I finally looked at my boost guage after a week of driving. I have a peak hold feture and after a couple hard runs I saw a peak of 8.7 psi. This is one the stock pulley (6 psi) that came with the kit.

We are both AP1, the differences qwe may have are I have the Moss manifold and high flow cat from berk. Just venturing a guess that the AP1 stock exhaust setup is too restrictive and causes higher boost pressure. WLAURENT has an aftermarket exhaust. I will probably go Mugen in the future (but not until next year) and I would bet that would bring my boost down. Car runs flawlessly though.

 

Just installed my Fujitsubo and have a Berk High Flow Cat and was expecting to see a little drop in boost. No dice. I have a peak hold feature on my guage and got the highest I have seen with the new exhaust on, at 9.2 psi.

The car runs just fine, although I would like to see that number drop. Most of the time when I hit it, it climbs to low 7psi range and then can spike on a down shift and a hammered throttle. Highest boost I think is in first gear (although I never have enough room most of the time to really run 2nd or 3rd that often)

I am reading boost at the dummy throttle body. The only difference between AP1 and 2 downstream is what , cams, header and compression?

 

[QUOTE=vader1,Jul 13 2009, 09:52 AM]
I am reading boost at the dummy throttle body.

 

Just went to burn in the Fuji a little more. A couple hard pulls, 11.2 peak boost. Stumped.

Think the Fujitsubo is gonna be too loud for me too.

Second exhaust installed and probably put up for sale within a week. Fool me twice shame on me.

 

what is the dim on the Fuji.



Intresting read and study on exhaust diams..

https://www.s2ki.com/forums/index.php?showtopic=710752

 

Saw that. I think the diameter is similar to stock. ~60.5mm to twin 50's or so.