Another little project- an intake air preheater

sk66

sk66

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Made a little fitting to mount a 12v glowplug in the upper plate on the intake manifold. I retapped the tee m10x1.25 and then cut a little bypass in the seat to allow the boost sensor to function (will mount in the side extension). The relay will get power from the GP relay supply, and will be switched manually. Initially I'm going to use the 6v relay trigger wire I already have installed... just unsure if I want them in tandem or not.

I don't have a block heater, and that doesn't help when off-grid anyway. And my van has never failed to start (down to 10˚f)... but it is really unhappy starting when it's that cold. I don't know if this will actually make a difference or not; but I believe it should (Cummins 5.6/6.7L engines use an intake heater instead of glow plugs).


intakeAirHeater.jpg
 
This is a great idea! I have this feature on my ford 7.3 from the factory. I talked with Mardy at amazing imports in BC years ago and he had suggested this when I was going through some of my cold start issues.
 
Well, I found out what happens if you apply voltage to a cheap GP for too long... they blow out the tip.
I had gotten some inexpensive plugs for a Hilux that were supposed to be self regulating... well, it didn't self regulate and at about 12 seconds it blew with a loud bang. I guess I'm lucky nothing hit me as I was bench testing the setup and didn't take any precautions.

So now I'm waiting on a couple ceramic plug options... One is a $25 glow/ignition plug for an Eberspacher heater that I'm not sure will work with this setup, but will arrive in a few days; the other is a $50 NGK that I know will work, but may not get here for another two weeks.

​

 
Curious how this works out. I started adapting a Dodge grid heater yeas ago but it remains yet another unfinished project on my work bench... along with my million other unfinished projects...
 
A little progress today. The Eberspacher ignition plug arrived so I adapted it and gave it a test run. I talked to GlowShift and they said I need to keep the temp ≤ 200˚f at the boost sensor so I added a 6" brass manifold for it. I ran it for about 2 minutes straight (this time in a can) and it was fine; which isn't surprising really considering it's intended use. I like this glow plug because it extends fully beyond the mounting plate, and it's cheaper; what I don't like is the somewhat clunky boost manifold and dual holes.

Starting from 72˚ the temp of the mounting plate/air reached 175˚, but the end of the manifold only reached 86˚f; the glow plug itself reached max temp (well/glowing red) in ~ 5 seconds.

At this point I am pretty confident this is going to work well. Hope to install it tomorrow...

Untitled-1.jpgUntitled-2.jpg
 
First test successful... with the engine cold soaked at 50˚f/10˚c I was able to start the engine with only the inlet air heater, but it took quite a while (over a minute pre, and held on during the start); the engine would not start without it... it was a pretty clean start, but it wasn't really that cold.

I will try again tomorrow morning when temps will be around 32˚f/0˚c to see what happens.
 
Well, it didn't seem to make much difference when temps are freezing; and I found out why.
For some reason, when pulling power from the 6v GP relay with the original wiring still attached (dropping resistor/glow plugs), it's acting like the two systems are in series rather than in parallel. I.e. the voltage is dividing between the loads rather than the current... I'm only getting 10v to the inlet heater and 2v to the GP buss bar.

I don't really understand why it's doing this, but the fix is simple... don't try to run both simultaneously off of one relay. I think I'm going to just disconnect the 6v circuit from the relay since I already have the manual switch/wiring installed. I wonder if the ECU will utilize it for afterglow; not sure what it is basing that function on?

But it is cold and rainy today, so it will have to wait for another day.
 
Final update; for now at least.
Firstly I found I didn't need to place the boost sensor very far away when it was actually cold, so to make it more compact and neater looking I redesigned it a little... I should have taken a picture of it installed.

inletHeater.jpg

Sub freezing tests (25f/-4c) showed it does make a difference, I had significantly cleaner starts... but as soon as the engine started moving more air it couldn't keep up. And since I had disabled the after-glow function it was a problem... I had to apply manual (12v) afterglow.

In order to use it I also had to do a double glow plug cycle, which is not something I typically do. I turned the key on and activated the inlet heater for ~20 count (probably ~15 seconds) and of course the pre-glow cycle ended well before that. So another pre-glow cycle while still activating the intake heater, and then start when the pre-glow cycle ended. The start was very low smoke; but I cannot attribute it solely to the intake heater as the process was different than normal.

For now I have removed it and restored the glow system to normal operating condition. I just wanted the van reassembled and usable as it's getting too cold to work on it in the driveway. It's not like my van won't start in freezing conditions as is... it can just get pretty smokey. I also don't drive my van much in the winter except occasionally for fun; or if we have a significant snow event and I need to drive somewhere.

I did acquire a ceramic glow plug to use instead, but IDT it would work any better (possibly worse) because the glow tip is much smaller; it just doesn't justify the added cost IMO. I don't have the ability to measure those kinds of temps, so IDK if one actually glows hotter.
 
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