jf4828

I purchased this car a few weeks as my 2nd FD project and I don't understand why my power varies so much! First, here is what im working w/....
Apexi Intake
Oversized Radiator(brand?)
Stock Intercooler
Full Greddy intake piping
Y Pipe
New stock turbos
Apexi ECU stock mapping
Air/Fuel Ratio Gauge
Boost Guage
Greddy down pipe
Stock Cat
Apexi N1 Exhaust

Ok, I'm running a very solid 13-8-13 boost pattern but the hp varies w/ out apperant reason? The fuel ratio is exactly where it should be and the ECU is putting out good numbers elsewhere. I often notice a change in the exhaust note which seems to be linked partially to the power of the car. I have checked from the downpipe to the catback and I see no signs of exhaust leaks..... That leads me to beleive that the Cat is clogged. The problem is that I don't understand why I wouldn't see a change in the boost when the exhaust note changes? I never get less than 13 before or after secondary. Another stupid question, how much of an effect does intake temperature make? The wide open intake system is right above the radiator fan which i suspect may be part of the problem....... Oh btw, compression is excellent so that is a non issue... Thanks

Joel

luneytune

I believe a clogged cat would reduce horsepower by restricting the exhaust but have no effect on final boost pressure. I would think you would need an extremely clogged cat to start limiting boost. IMHO

jkprelude

If your boost is running the same every time...and there is no compression problem...and you can maybe hear an exhaust note change...how do you know that you're loosing horsepower? Did you do a dyno run and notice this? Or can you just feel a difference? It sounds like its a great running RX-7.

jf4828

Well, basically the tires go from breaking lose in second gear under full throttle to not. 115 merging on the interstate ramp I drive every day to 100mph.... I suppose it is probably just that damn cat? I can't wait till my midpipe comes in Anyone know much about the intake temperature? My power FC registers ~ 80C air temp... What is a good temp range reading on the power fc? What sensor does it read from?

CCarlisi

ditto-I have posted about this in the past.
On good days it seems as though my car has more horsepower BEFORE BOOST COMES ON-it pulls away at low rpms better, slams me back in the seat much harder under boost, and generally seems to rev faster.

On bad days it feels like the displacement has dropped by 40%. Everybody is quick to point the finger at heat soak, but I haven't found a direct coralation. Yesterday for example the car was very strong yet the intake temp was 70 degrees and the water temp was hitting 100 at times before the fans kicked it down to 92. I was stuck in stop and go most of the time so I imagine my stock IC was nice and toasty. On the other end of the specturm there have been cold days where it has felt dead with intake temps in the 40s. Temperature does seem to have an effect, case in point a slow day in the summer is slower than a slow day in the winter, but in either case there seems to be another variable that is not directly connected to heat soak.

If we eliminate boost as a possibility, we have fuel and timing. I don't have a solid enough understanding of either of these two areas to formulate a hypothesis. If anyone feels incline, I'd be interested to hear some thoughts on this.

-Chris C.
The relevant mods:
bottom feeding intake(CWC style)
PFC
DP
CB
new hoses, ck valves, solenoids

jf4828

CCarlisi, you hit the nail on the head. I feel like I'm driving my own car. I can't make a correlation for the life of me??? I do know that when the water temp goes up some power is restored because the air temp goes down, but not always full power. I will PM you once I build the cold air box and replace the cat w/ a mid pipe.... Hopefully this will solve this problem... In the mean time i guess it's a guessing game?