New exhaust.. Turbo lights go crazy

[Syzygy]

I've just put a 2.5" mandrel exhaust from the turbo back in my lj70. The car is a lot nicer to drive and has a really good sound. Can hear the turbo much more now. The exhaust is actually quieter at high revs and overall i'm really happy with it.

I took it on the freeway tonight (110km/h) and noticed that the turbo lights on the dash were behaving differently. in the past, the green light came on under light load, and under heavy load the red light also came on. But now, both come on, then the green one goes off. Cant understand why there would be a change...

The car is much nicer to drive at 110, but the red light stays on... I'm guessing the top speed has probably gone up at least 10-15km/h. Although, i have a hill that i regularly test things on. and the gain is 0%. absolutly nothing. the numbers (speeds bottom and top) were exactly the same in both 4th and 5th as they were last time i tested it.

 

[denis]

You have less backpressure behind the turbine, which can spool easier especially at higher revs. You have more air, but not necessarily more power depending on the fuel adjustment. If you turn the max. boost pressure down you may gain a bit of efficiency by not pumping unnecessary air, if you keep the boost higher and turn the fuel up you may improve the efficiency as well because the revs. will be lower for a given power. Also, more power = more heat, you may want to take that into account.

The lights are not always accurate, the senders may be acting funny because they're ont working in a pressure range they are used to.

 

[Stone]

Put a turbo gauge on. Better yet, put a turbo gauge and pyrometer on...especially on a 2L-T. That way you will know if the turbo is really generating that much pressure (ie. wastegate issues) or if your sender is doing funny things.

Orange light is supposed to be over-boosting...and if it comes on it's not good. The orange light on my 13B-T BJ74 has never come on except when the ignition key is first switched to "ON" before cranking.

The green light comes on as soon as there is anything higher than atmospheric pressure. Mine comes on at 1 PSI.

 

[Tapage]

Just wondering ( and always learning ) in a turbo setup the backpress issue is also afected in the same range as a non turbo setup when you put large exhaust tube.?

 

[denis]

Just wondering ( and always learning ) in a turbo setup the backpress issue is also afected in the same range as a non turbo setup when you put large exhaust tube.?

The pre-turbo backpressure will equal post turbo backpressure times the pressure ratio across the turbo. 2:1 will be typical, 3:1 or more can happen in small turbine/ high boost setups.

 

[Tapage]

The pre-turbo backpressure will equal post turbo backpressure times the pressure ratio across the turbo. 2:1 will be typical, 3:1 or more can happen in small turbine/ high boost setups.

Thanks for the info Denis ..

 

[crushers]

run a boost gauge and forget about the idiot lights. better peice of mind...