Hi, Can anyone help? I have increased the boost on my volvo from 7.5psi to about 12.5psi using a bleed valve on the wastegate pipe. On full throtle acceleration in 1st and 2nd I sometimes get a kick it's like taking your foot out and then back on the throtle. I understand that there is a boost control switch/valve that shuts down the fuel pump if the boost is too high. The curcuit diagram shows it but the question is WHERE is it? Some have said that it is near the pedals teed off the boost guage pipe, mine isn't. Does anyone know where it could be? This mod makes the 940 a prety quick car!!
I second that. The B230FT engine will NOT take 20 psi for more than a few moments, and in any case you need some safety precautions in place before you go upping boost, like an AF meter and accurate boost gauge. You may be hitting fuel cut off, but more likely you are experiencing compressor surge.
There is alot to know.
Learn the flow map for your particular turbo, and keep within it's parameters when you are considering a G Valve or bleed to raise boost. Go to T-Bricks and begin to learn how to safely raise boost, or you will be learning all about rebuilding detonated engines shortly.
Iv'e a lot of experience with tuning engines. I was runnerup in the national drag racing championships twice. I built the engine up from 230hp to 600hp relyably.
But that was old technology. no knock sensors or oxygen sensors.
I just wanted to know where the boost control switch was located on the car.
The control switch is behind the drivers knee panel, under the steering wheel. But, there may not be a switch there at all. Some models didn't include it, so in that case, it is probably surge. Check Turbo bricks for specific models. If there IS a switch there, you can carefully dig out the glue, and re-adjust the screw to cut off later, but...take care.
Surge happens when the compressor forces more air into it's turbine side than the turbine is capable of handling. For instance if you turn up the boost via a bleed or G Valve, and are asking for 16 hypothetical lbs from a turbo that can really only handle 12 psi, the compressor will be forcing more into the turbine side (or surging) than that turbine can handle. The effect is that the car seems to be stalling, or briefly lurching. It can repeat a few times in quick succession. If you can get a hold of a compressor map for your specific turbo, you can see what the safe and reliable PSI range for your turbo is. You may be able to get 20 lbs right now, but if you are running out of fuel, or getting compressor surge, it might be time to turn it down a bit before you melt a piston, or get a bigger turbo.
It's a rare b230ft that will reliably run 20 psi all day without some fairly hefty mods, although I know guys who run around 18 without heavy mods. It's do-able for sure, there are crazy Swedes who get 700 hp, setting it up as a drag motor. But get ready for some serious $$ if you want to extract that kind of power from a 4cyl Volvo block.
I have no knowledge of a B200 engine. To be honest, I never heard of that engine before tonight, and thought is was a typo. I continue to learn.
I think you have fuel system LH 2.4, which has the overboost function built into the ECU program. The ECU compares signals from the air mass meter and compares it to engine RPM. If it "thinks" there's too much air going in, it turns the fuel pump relay off. Other fuel systems have the pressure switch you're seeking.
Thanks - that make sense. I talked to IPD about it a little while ago and Scott reassured me that 18-20psi is fine on the 99 R motors. Seems like it's pushing the edge though - especially with the crappy CA gas that I have to burn.
I have discovered (for my self and my driving style)
18-22 psi is just too much power for my 1993 940t... the rear tyres always break loose, and the car is fast ... so fast, I didn't feel very safe drivin' it like that... all the time ... I would not let other folks drive the car, as you had to "know what you are doin'" to keep it under control and out of "dicy situations".....so, I turned down the boost to a more confortable setting...I think I hit 8-12 now...It seems nice, smooth, and strong....my only weak point is/was the tranny......a buddie of mine who is tweeking his 93 940t in a "big way" put in a bmw tranny w/some upgraded plates and clutches...he told me it works like a dream...smooth, and no blow ups w/all the extra torque and power.....the b230's are a great platform to build up on...that's for sure......(imho)
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