How much does altitude affecte an NA IDI

[tractorman86]

I mean't 15 psi of manafold pressure, the book siad that the less air density the lowere you manafold pressure is. Mabe it is valuble to get a manafold pressure gague and see how the pressure changes as I gain altitude.

huntersbo:i believe they are mainly speeking about flying around 20K and higher

 

[Huntersbo]

I think so too, but couldn't you run more boost at higher altitued such as 7000 feet copared to sea level to gain back the lost power?
Actually I was 4 wheeling in Big bear with my cousin in his jeep and he said that his jeep ran better up there than back at his home in Palm Springs; more power he said. He did have EFI though. Boost or backing off on the pump I would think best at altitude.

 

[RLDSL]

anyways, on the drive up 395 my truck runs fine until i get to bishop where it's about 5,000 ft. then there is a long(i'm guessing 10 mile) 6% grade that starts at around 500 and ends at close to 7000. completely empty i blow black smoke and have to keep it at 3200 rpms to hold 60 mph. that's not the case back home where i'm a mere 800 ft. above sea level.

around town where it's 8,000 feet, there is a noticeable loss in power. slow acceleration, hard starts. black smoke when you're barely on it, and things like that. despite the power loss, i was one of the few vehicles that managed not to get stuck, and i pulled many a small car out of the snowbank.

at 10,500 you're going to see a lot of power loss. just curious, but where in the sierras are you going?

Ah yes, Sherwin grade I believe it is. Used to pull that sucker in a semi a couple of times a week. Way back when going skiing in gas burners , alot of times we'd have to get out and pull the air filters or flip the lids to get up that thing.

But back to the original question, if you cut the fuel back and advance the injection timing a bit it will help a bunch.
Most of the european diesel cars have instructions for this in the factory manuals and some of the later models have automatic altitude compensators that cut the fuel back and increase the injection timing above about 6000 ft I believe it is off the top of my head ( too lazy to go down and look in the books

I guess on these beasts they just figured there was enough spare oomph to at least get over the hills without having to adjust anything

All new computer controled engines make these adjustments automatically.

----------Robert

 

[tractorman86]

All new computer controled engines make these adjustments automatically.

----------Robert

yea but as soon as something goes out you are skrewed!

 

[f-two-fiddy]

Hunter you misunderstand how a wastegate works... A wastegate is nothing more than a pressure relief valve of sorts - meaning that once a set psi is reached then it will start to open which starts to limit the boost. Now operation of the wastegate will be the same at sea level at is at 10,000 feet meaning if the system would produce 10psi of boost down low it will only produce 10psi at alt. Now the amount of air in 10 psi at SL is the same at 10k so adjusting the wastegate would buy you nothing other than you would then produce more boost at both alt's.

This is exactly why I've been saying that adjusting the wastegate is not worth it.
Instead, go with a Boost Controller. There are many types that will work well. You can spend as little as $75, or as much as $600. Heck, you could make a fishtank bleeder type, for $12.00. (not the route I'd take)
As soon as I get an IC setup, I'll be going with a Hallman Boost Controller

 

[Huntersbo]

HALLMAN PRO KIT:

Our new Hallman Pro kit contains our new Hallman Pro valve. The new Pro valve is machined out of billet aluminum and stainless steel pieces. The new design of the valve incorporates some great new features not currently available on any other manual boost controller.

We have designed the Pro valve to not require the use of a lock nut or any type or allen wrench(s) to be able to adjust your boost. Simply turn the adjustment knob and it stays. Another great feature is the fact that the adjustment knob cannot be lost or come out of the valve. Simply put there is not a potential for overboosting since the adjustment knob cannot vibrate loose and come out.

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Hallman Pro $105.00

I like this one since I was looking at the powerstoke turbo which is said to make more boost than the IDI can take; I unerstand that as I drive up a mountain and gain elevation I can increase boost to regain that power loss; starting from running max safe boost at sea level and adding from there as I go up.

 

[f-two-fiddy]

The only problem with the Pro Kit is that you'll have to pull over to turn the knob. An incab/cockpit Evolution setup would be much more convienent

 

[Huntersbo]

In cab was what I had in mind.