Loss of power around 3600 rpm
 

I have installed the JimB intercooler pipes yesterday. (btw i have ordered those pipes 3 weeks ago and received them this week in The Netherlands, so i dont have the same experiences with Jim as some other people do)

The car behaves a little strange now. Around 3600 rpm it feels like there is powerloss, like the engine holds back. At this point the turbo starts spooling. At 4000 rpm everything is fine again and the power comes in. Any idea what causes this behaviour??

Is this because of the new intercooler piping? Because the way the air is traveling is longer now??

Could be your exhaust, what you got at the back ?
Your in Holland ?
What type of fuel are you using over there ?
I'm in Ireland using the usual unleaded stuff, standard Greddy at 6psi (tighten that waste gate rod up and get more power for your kit). You could set your base timing to 7 or 8 to be safe.

Is is possible that the bipes is seeing so much air flow, that it's pulling timing and it doesn't have to?

Dave

Sounds normal since the intercooler is adding a fair amount of restriction to airflow. Easily an initial loss of over 1 PSI boost. With the cooler intake charge can get a bit more aggressive with the Bipes.

Could be your down pipe and exhaust.

Could be that you are getting earlier spool while still in closed loop and the ECU is not allowing enough fuel to keep the mix rich enough for that extra boost until you hit open loop at ~4000 rpm.

That sounds righgt.

I still have the standard exhaust but replace the cat with an empty one.

Yep. I use the 98 super unleaded fuel. That's the fuel with the highist octane number in Holland.

My base timing is at 12 degrees and retard it with the bipes to 6 degrees at 3800 rpm. I have tightend the waste gate rod to 5/6 psi.

How can i change this? Other bipes settings??

https://www.miataturbo.net/forums/showthread.php?t=2572

The first picture in the first post in this thread gives you a schematic to make an oxygen clamp. They are also available premade from FM and myself.

Basically it fools the ECU into thinking the mixture is lean and keeps it from pulling fuel as you enter boost or adds fuel if you set it lean enough.

98 octane from the pump huh? thats cool :cool:

Well, actually, i believe the european 98 super equals 91 octane fuel in the USA. So it looks nicer then it really is :td:

Actually, I'm pretty sure their octane ratings, even though different from ours, are still better no matter what. Especially considering they don't have MTBE poisoning their pumps. Plus the Shell Supermax and BP's highest octane is well above anything we have with the possible exception of 76 96 octane which is becoming increasingly rare.

or he's hitting 6psi and the flapper is going wide open, causing it to go rich :dunno:

Nope, they're not. Many (most?) places still calculate octane using only the RON rating, while the U.S. uses RON+MON/2. The Shell Supermax is rated for something like 100 or 101 octane on the RON method, which translates to ~93-94 octane in the U.S.

The 98 octane that Andrepascal puts in his car is actually a slightly lower octane than the 93 I put in my car.

"My base timing is at 12 degrees and retard it with the bipes to 6 degrees at 3800 rpm. I have tightend the waste gate rod to 5/6 psi."

This is a problem - close bipes switch 5 & 6 to 'Open' only retard 2* and set switch 7 & 8 to 'Closed'.
Here is my Bipes map for the same set up, 6-7psi, 91 oct, Jimb pipe & Starion IC.
From 1-10 = ooooooccoo (o= open c= closed).

Thanks, i will try these bipes settings right away

I have installed a simple air to fuel meter in the car, using the original o2 sensor. I know this isnt accurate (seems more like a disco light) but it probably can give me a hint if i have a rich or lean fuel mixture at 3600 rpm...


I keep you informed about my findings!

I have tried the settings bartsimpson suggested for the bipes and the power loss seems almost gone now. So i probably used to aggresive settings on the bipes. I will test some more with the bipes settings the next couple of days! And maybe it is still a good thing to install the o2 clamp. Thanks for all the input!

Andre Pascal

awesome.

93 octane here in Norf Cakalacky. Of course it's a little cheaper over the border in SC. One of the good benefits to living in NASCAR country is the number of stations that sell 110 octane at the pump.