over boostin fc

stuart wizy · July 25, 2007, 11:13:43 PM

took my new cab out today for the first proper drive since I got it.
its totaly std with a rebuilt motor 18000 mile ago, my first blast in first gear just spun the wheels, 2nd lag lag and a nice kick back in the seat then revs cut at about 6 k rpm and wouldnt let me rev past 3k rpm so i pulled over and shut of the engine and reset the ecu, then I started it back up and it was back to normal free reving to red line.
the car has been stood for 2 years until now so has anyone any ideas why its overboosting?
im gonna try a boost gauge in it tommorrow to see what boost its reaching so does anyone know the std boost on a fc?
cheers
stu

Brett · July 25, 2007, 11:19:30 PM

Around .4 bar is standard:)

McPie · July 26, 2007, 11:20:52 AM

I have same ****.

But I drive nice ~10min and engince start\'s fuel cut, I think that it is starting. But Firstly I\'ll try to change all hoses, especialy vacuum hoses. Because on of them was broken in 1700km redline tour latvia.
I also made an FCD, but propably it got wet, do not work, any ideas?

Prof · July 26, 2007, 11:23:38 AM

Turbo II engines - should be 5.5 PSI on the spring, and the boost solenoid (operated by duty cycle from ECU) should raise this to about 8psi.

However if you mod the intake or exhaust for freer breathers, you can expect this to rise and without a chipped ECU or FCD you\'ll get fuel cut at 8.8 PSI.

stuart wizy · July 26, 2007, 01:33:31 PM

im gonna but a boost controler on it and fcd, straight through exahust, air filter and bov. Ive just got a wideband for my drag car to check my afr when I wind the boost up to see what stock ecu can take boost wise.
should be fun!!!

beezy · August 29, 2007, 10:49:37 PM

Whats a good safe boost with good power.

Also what sorta max limit that a rotary will handle?

Brett · August 30, 2007, 09:44:40 AM

With FCD, 3" turbo back, BOV and panel I was making over 200atw - when I got a chipped ECU it went up more and there was loads more mid range torque. Max power was around 6500rpm, this was at 0.9bar in 4th gear. :wave

stuart wizy · August 30, 2007, 10:30:37 AM

brett what do you control your boost with? and where have you piped it up?
Ive pluged the standard boost feed to actuator with a bolt and took a feed for boost controler from plenum then from boost controler out to actuator.

Brett · August 30, 2007, 10:50:12 AM

I was using a home made bleed valve - plumbed in before the control solenoid. This time around I may go for an electronic boost controller... (As and when I get my hands on the top mount and another 3" system)

A more basic method would be to add a restrictor in the down pipe - taking the ID down to around 2" or something - you would probably see a peak of 0.8-0.9 bar like that...

beezy · August 30, 2007, 04:53:54 PM

Ok chears, so what could i put the boost up to (Max)
That a rebuilt rotary engine can take with these mods?

turbonetics turbo
greddy pipework
alloy radiator ( v-mounted with 2 electric fans )
v-mounted intercooler with electric fan for extra cooling
blow off valve
calsonic oil cooler
apexi power fc with commander
greddy profec b boost controller
uprated fuel pumps and swirl pot in the spare wheel well
550cc primary injectors and 1000cc secondaires
uprated leads and HKS plugs
3.5" from manifold back to the back box and small centre box
stainless back box 4"
power steering pump moved to get better pipe run for the intercooler
ITG air filter
fuel pressure regulater

Thanks Jon

beezy · August 31, 2007, 05:14:14 PM

Anyone??

Its running 1Bar.... Will it be saft to put upto 1.2Bar?

Brett · August 31, 2007, 05:18:16 PM

Its hard to be certain - what spec is the turbo? Providing you are not generating too much heat 1-1.2bar could be possible... But I\'m no expert.

Prof · August 31, 2007, 05:50:57 PM

It will all be down to the cooling - certainly enough fuel for it, and with a power FC you can take advantage of the bigger secondaries - but heat in the intake charge is going to be your limiting factor.

So many factors like the bore of the intecooler pipework, the size of the turbo, the intercooler efficiency and the airflow across it. Also, if you\'re running vmount, have you still got the original Tubby II bonnet, or are you using a different one ?

Something like water injection would help provide a safetey margin.

beezy · August 31, 2007, 07:05:14 PM

Quote from: ProfIt will all be down to the cooling - certainly enough fuel for it, and with a power FC you can take advantage of the bigger secondaries - but heat in the intake charge is going to be your limiting factor.

So many factors like the bore of the intecooler pipework, the size of the turbo, the intercooler efficiency and the airflow across it. Also, if you\'re running vmount, have you still got the original Tubby II bonnet, or are you using a different one ?

Something like water injection would help provide a safetey margin.

Ok great, thanks mate!!

Yes its a Tubby II bonnet aswell but i would like to det something like this...

Prof · August 31, 2007, 07:22:28 PM

Quote from: beezyOk great, thanks mate!!

Yes its a Tubby II bonnet aswell but i would like to det something like this...

Just get one that fits better than that one - lol :Laugh

I\'ve seen carbon fibre bonnets with that grill pattern on eBay in the US - would cost a bit to bring over - but would be nice and light and a good replacement for the ally bonnet. Would help keep the heat out of the engine bay. Also with a vmount setup, the front lip will help a lot.