Increasing diesel engine power 2

[FZR1KG]

I've noticed that in hot weather I get less power out of my engine and also I get less power out of it when it warms up fully.
I'm guessing that this is because the intake air heats up so I have less air density.
My car has a turbo and an inter-cooler, more correctly an after-cooler.

I just thought I'd ask here if insulating the air intake lines in the engine bay before it enters the turbo would reduce the heat absorbed from the engine bay reducing the final intake temperature.
Would it be worth trying or is it a waste of effort?

 

[LadaTrouble]

No smoke on an indirect injection diesel? Get someone to confirm that from the rear as you are under full noise.It may be under fueling,which will explain the power loss.These things are pretty dirty and should have a little black smoke under load.I'm in NZ and pretty familiar with small Japanese diesels...we have a Courier at work that has done 1,450,000km,and still won't lie down.It's very gutless of course,a joke in the company considering we are a Mitsi dealer.

 

[FZR1KG]

Will try to do that this weekend. We're having guests over so I'll see if he minds following me.
Good to see the reputation of the courier engine is going strong, 1M45 km, thats some mileage!

I don't understand why there would be power loss as it warms up if it was under fueled. Shouldn't it be the same low power all the time?

BTW, my mate has a Triton dual cab diesel. My courier is faster than his and his is a later model, not sure what thats all about LOL

 

[winfieldblue]

The "fast idle valve" might be retarding the start of injection if it's the same set-up as the toyota rotary pump which has the engines coolant running through the sensor. I disconnected mine, and then burnt out a set of glow plugs every month, melting the tips off them! Retarding the injection timing fixed this problem.

 

[LadaTrouble]

Yeah,you have to use a 10mm spacer jammed into the coldstart when setting the timing on those engines.But his 02 courier should have an electronic pump,so no cold start valve.

 

[70btdc]

I think you would be surprised to find that your intercooler CORE temp varies almost exactly as the performace does.

If you say you can sit and idle for 5 mins and still have performance for a short distance, why wouldn't the pre-compressor intake pipes already be up to engine bay temps? If the intercooler is far enough away from main engine bay heat soak (at the front of the car) then it will not heat up until the first time you compress the air. If it is small in size, or poorly positioned in the airflow, the core may never get back to the ambient temp in normal driving, acting as a heat soak, controlling temps below a certain level but also not allowing minimum temps to be reached again.

Have you got a cheap multi-meter with a k-type probe? Epoxy the sensor to the IC core, tape the meter to your windscreen and have a drive. Also check your intake piping temps between the compressor and IC, you will see that they will return to closer to ambient temps alot quicker.

A larger or more efficient intercooler is the answer.

 

[Compositepro]

FZR1KG, I don't mean to be pedantic but your rule of thumb of the temperature doubling is based on a common but very serious error that needs to be quashed. It can only apply if you are using an absolute temperature scale and then the factor would need to be adjusted to something like 1.1. For example, if the outside air temperature is 0C or -5C what will the boosted air temperature be by your rule?

 

[FZR1KG]

Compositepro,
No worries. I don't think you're being pedantic. More that I wasn't clear in what I wrote. It wasn't a doubling of the temp in DegC I was using to get that figure, I found that error earlier when I forgot to convert to Kelvin in my quick spreadsheet to get me a rough idea and entered a neg temp to work out what I was seeing in the early winter mornings. It got colder as a result of being compressed! LOL

70btdc,
You have a very valid point.
That would also explain the effects I'm seeing.
I'll flush the intercooler and raise it up so its more into the air flow and see what happens.
I no longer have a multimeter with a thermo couple input. I had a great data logging multimeter till I lent the thing to a co-worker. Now I have a fancy paper weight.

Just curious, how would I calculate the required size of the intercooler for this car. Its a 2.5 litre turbo with about 15psi boost. Produces about 90kW of power if that is a factor.
While its not blocked due to oil from the PCV, how much would a film of oil in the intercooler affect its efficiency?

 

[MrWFO]

methanol or water injection.

 

[rmw]

As a heat transfer engineer by day (job), I would say that unless you are interested in calculating to the third decimal place, the heat transfer through your tubing walls is negligable. The only help you will get by doing that would be your feelings. I work with an intercooled gas turbine and we would LOVE to get some credit for the heat lost by the tubing walls pre intercooler but sorry, we have to do it with lots and lots of (expensive) heat transfer surface area in the intercooler. And, yes, our Brayton cycle machine suffers when the temperatures get up to summer time levels. Enough that there is a measurable difference between early morning and mid (Hot) afternoons.

The post about the potential underfueling condition caught my eye. Otherwise, I think you are just dealing with the ravages of the PV=nRT law. Hotter air has larger volume and it affects turbo performance, tube wall friction, after cooler efficiency and effectiveness, fuel properties, etc.

I drove a turbocharged IDI diesel for years and I can't say that I ever noticed any difference hot to cold, but then again, my turbo may have had as much shaft horsepower as your little 4 banger. (See tongue in cheek.) But that said, mine was way over fueled, and if anything I had problems in the other direction due to that.

Typically a turbo will spool up and overcome lots of the detrimental effects of hotter air, but if you are underfueled, you will never push your turbo hard enough to spool it up to make a difference.

Remember too that at a hotter starting point, the turbo exit temp is hotter and hotter air has a higher volume which causes increased pressure drop through your after cooler. It is all working against you.

Go for checking the fuel system. I think that is where you will get the biggest bang for your buck (quid). Changed your filters lately?

rmw

 

[FZR1KG]

Well, its seems like its a case of mainly under fueling.
A quick adjustment to the fuel delivery made a world of difference.
I say mainly because it still has the same symptoms but much milder.
Before it would get quite sluggish, now its just a slight power drop. Its noticeable if looking for it but otherwise it drives like it should.
I'm happy with the results. When summer hits I'll see if it makes any more change to the performance but right now its going fine.

Thanks for the advice everyone.