3lt Nissan Patrol Exhaust

Submitted: Monday, Jun 09, 2008 at 19:47
ThreadID: 58571 Views:2471 Replies:3 FollowUps:4
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Before I did my trip out west I fitted a exhaust temp gauge and a boost gauge as I have a concern about Nissan engine failure.
One thing I noticed was while towing that if I didn't change up quick enough or didn't take the boost to 32psi the boost dropped down to 0 psi and the exhaust rose by approx 100c. As soon as I backed of the accelerator and slowly increased the boost rose the temp went down. It appears to bog the turbo down for some time and increase the exhaust temp, is this normal as this was my first time towing with a turbo diesel .
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Reply By: TD100 - Monday, Jun 09, 2008 at 20:06

Monday, Jun 09, 2008 at 20:06
My friend if you can get 32psi out of it i would be running the other way before it goes BOOOOOMMMMMM !!!!
AnswerID: 308855

Follow Up By: Member -Captain Chaos (QLD) - Monday, Jun 09, 2008 at 20:11

Monday, Jun 09, 2008 at 20:11
What is the max boost it should have?
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FollowupID: 574880

Follow Up By: Member -Captain Chaos (QLD) - Tuesday, Jun 10, 2008 at 17:22

Tuesday, Jun 10, 2008 at 17:22
sorry should of read 22psi
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FollowupID: 575078

Reply By: Trevor R (QLD) - Monday, Jun 09, 2008 at 20:54

Monday, Jun 09, 2008 at 20:54
I know it is different vehicle but hope this helps in some way.

My 4.2 Patrol is set to max 14psi and at no time does the turbo "bog down". If I stick the boot into it then the boost just goes up, keep the boot in for any length of time and so does the EGT's. Also if I leave it in too high a gear and labour things, the EGT's will similarly rise.

I was worried about running my 4.2 at 14psi but this seems ok as I have now got 360 000km on the clock all with modified hp figures but only the last 100 thou with the 14psi (was at 11psi from new). Each engine model re-acts different to differing boost levels, someone has put a link up to Lonard's Auto and I would definately call someone like him to get guidance surrounding your engine.

Regards,
Trevor.
AnswerID: 308891

Follow Up By: Member -Captain Chaos (QLD) - Tuesday, Jun 10, 2008 at 06:05

Tuesday, Jun 10, 2008 at 06:05
thank you will be making a phone call first up today
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FollowupID: 574959

Reply By: Chaz - Tuesday, Jun 10, 2008 at 07:55

Tuesday, Jun 10, 2008 at 07:55
Captain Chaos,

32psi is way too high and I’m surprised it doesn’t go into limp mode after that.

The reason your boost drops under load is because the ECU reduces boost to promote EGR. The VNT system is completely ECU controlled unlike a conventional waste gate turbo like the 4.2 and Navara use. What you are seeing is normal, but the boost level is too high and you will have problems such as leaking intercooler or blowing off or splitting cooler hoses or possibly worst.
There is a simple fix for this problem and you can adjust your boost to a safer level. I run a maximum of 18psi under full throttle at 4000rpm, but my boost rarely goes over 15psi. Driving in the city, I don’t let it go over 9psi. My EGT’s rarely exceed 250C in the city and 400C on the highway and my boost doesn’t drop under load.
This is how I did it
18psi should be a safe limit for an engine with 17:1 compression ratio, but for long engine life I run the lowest possible boost to achieve acceptable EGT’s which I’ll never let go over 450C.

Chaz's Patrol
AnswerID: 308949

Follow Up By: Member -Captain Chaos (QLD) - Tuesday, Jun 10, 2008 at 17:27

Tuesday, Jun 10, 2008 at 17:27
As you will see I typed in the wrong number should of been 22psi,I am getting the same around town as you.
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FollowupID: 575079

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