11.5\9\11.5 boost pattern...dangerous??
 

I have an 93 FD with a 3" cb\dp, stock mp, ported wg and twin air filters. Took it for a test drive and i was very happy to see no boost creep or spike . But its the 11.5 psi of boost that's scraring me aaaaaa little.

So, the question is...is it safe and reliable to run like this or should i find a way to lower the boost to 10 psi??

Another question :P !!! Do you think i won at least 20 hp on flywheel??


""note"": i did my research on the forum and i only found people with boost creep\spike or no boost problem.

check the thread in the advanced tech section about running 10psi of boost.

you probably gained more than 20hp with those mods :)

You should lower your boost to 10 psi to be safe.

1) Cool air temps will do that. I have a couple of flow mods and my boost can elevate 1-2psi. Therefore I don't max out my boost in cool weather (fortunately, I'm not driving it in general when it's cold/winter). 12psi is not good.

2) Check the zero on your boost gauge, or take another pressure gauge and tee it in for a test. Could be the gauge is reading a touch high.

Dave

if you are on a stock ECU then you are just asking for problems at 11.5 psi

oh ooh
 

you dont want to look for problems with an fd....

i just did a test drive with someone outside the car.... theres is no black smoke comming out from the exhaust a wot....its reallly running poor then

running poor you mean running lean? I assume that running rich results in black smoke at WOT, which is in a way, a good thing?

thats my opinion... i prefer to see some black smoke, meaning it runs rich.

Boost Gauge Accuracy
 

Is it really 11.5 psi? Has your boost gauge been calibrated? Some of them are not very accurate.

you will not see black smoke out the tailpipe if you are running a stock cat.

spend some time reading all the good info collected in the stickies so you can learn more about the car and what not to do.

MMmmm
 

Yes, i use the autometer carbon fiber boost gauge. I didn't calibrate the gauge...

My autometer boost gauge sucks ass. But luckily I trust my profec spec II to read accurate boost :)

My autometer guage was always 2psi off from the PFC read out. I believe you hit some built in ignition safety cuts at or close to 12psi on factory ECU if I remember correctly. It varies based on RPM on what the Factory ECU will allow, to help with the boost spike transition period, etc. 11.5 is kind of pushing it in my opinion, but only if the autometer guage is reading correctly. You might be running 10/7.5/10 in all reality.

Before you do ANYTHING more, calibrate the gauge against an accurate pressure gauge. It could be low, in which case you're in trouble, or it could be 2 psi high, in which case you are OK. You don't know unless it is accurate.

boost accurancy
 

ok, let say my boost gauge is not accurate....

Do you think my car boost between 10-11 psi, 11-12psi or 12-13psi ?

my mods: cb\dp , ported wg, twin air filters and everything else is original.

with a ported wg it sounds like a 10/7.5/10 setup. with your autometer gauge reading 1.5-2psi high. Just like the other guy said though, calibrate your guage before you run the car hard again.

Rob,

Did you have your boost gauge installed before the mods were added? I'm guessing not.

My boost gauge reads 12 psi when I'm actually at 10 psi. But that's *MY* boost guage. It's actually accurate up to 5 psi then after that it goes to crap. It's not a linear deviation either.

Just for your info:

The ECU is programmed to cut off fuel at the following ABSOLUTE pressures. If You live at sea level, your maximum boost gauge readings should be less than the third column values. If you run at higher alttudes, you can boost a bit more.

I can't view it. What does sea level state?

edit- Thanks!

I changed the file type - try it again.

Dave thanks for the mappings. I knew it peaked around 4500, but I didn't want to go look for the details.

Not true! If you granny drive the car around a bit or you let it idle for extended periods of time, you will get alot of un-burned carbon deposits in the exhaust which can & will burn off during a WOT run. I don't usually drive the piss out of my stock car but when I do, I see a crap load of black smoke out the rear end. After a few more runs the black smoke goes away.

^^ odd. mine doesn't do that at all. mods in sig.

Ok, before i do any mods on my full stock fd, my boost pattern was 9\7\9 with the same autometer gauge and with a very dirty air filter.

My point exactly! What did 9/7/9 mean? Was it actually measuring 10/8/10 and reading 9/7/9, or was it really 9/7/9?