[ao.frog]

Hi.

I'm about to try the first hot start on my Extreem IO-360 with no purge valve and dual P-mags.

I've checked the POH's available on this forum, and it seems that the most common way is to skip the priming with the fuelpump and mix. Just to turn on the mags and switches and crank and then feed in the mix gradually.

On the previous prop-aircraft I've flown, (Cessna + Cherokee with carb's) the procedure has been also to pump the throttle slightly.
What techniques does you people use on a FI engine when hot starting?

Thanks!

 

[RV7Guy]

Easy stuff

Hi Alf,

This is very easy. I live in AZ and operate in some of the hottest climate possible. I've taught this technique to several that are new to hot weather living.

1) Mixture full rich
2) Throttle full
3) Pump on for a few seconds, then off
4) Mixture off, pull
5) Throttle in just a little
6) Crank, the engine will turn and start for a second. DON'T DO ANYTHING ON THE FIRST IGNITE. Keep cranking. The engine will grab again. When it does, push the mixture full rich and pull the throttle to idle.

This make take a couple of times to get the timing down to catch the second ignition. If it doesn't work, do the same steps. You'll get it.

Very simple process that I've taught many.

 

[sjhurlbut]

My technique is exactly as you describe. I once flew 20 famil flights in 1 day and got the hot start technique down. If it has sit for more than 5 min I give it about 1 sec boost. Otherwise just leave the mixture at cut-off and throttle a bit above idle and crank. Mixture full rich after start. May also need to increase throttle to get 1000 RPM initially.

After it starts watch the fuel pressure carefully. More than once on hot days I've had to turn the boost pump on because of vapour lock. Once the hot fuel has circulated you can turn the boost back off. About 30 sec or so.

Steve
RV7A Flying 2 years
Mattituck Red/Gold TMX IO-360

 

[RV8iator]

Just about the same..

I do almost the same as the two above with the exception that when my engine it hot I always go to throttle and mixture full rich and hit the fuel pump ON for about a second. I have not had any trouble starting my hot engine this way.
When cold I prime with the pump and throttle and mixture full forward for about 3 seconds and it always starts on the first or second blade.

 

[Geoff]

Hi.

I'm about to try the first hot start on my Extreem IO-360 with no purge valve and dual P-mags.

I've checked the POH's available on this forum, and it seems that the most common way is to skip the priming with the fuelpump and mix. Just to turn on the mags and switches and crank and then feed in the mix gradually.

On the previous prop-aircraft I've flown, (Cessna + Cherokee with carb's) the procedure has been also to pump the throttle slightly.
What techniques does you people use on a FI engine when hot starting?

Thanks!

I use a similar technique to the other guys who answered (either no prime at all or only a second or so), but I start with the throttle at about the 1000 RPM position (as opposed to full) and the mixture at idle. If it doesn't catch in a few blades, I start slowly advancing the throttle until it does. When it does, I pull the throttle back and advance the mixture.

The idea here is that you don't know how much fuel is in the cylinders, and hence you don't know how much air you need in the cylinders to get the fuel to burn properly. In a hot start there is almost always too much fuel. At some point between idle throttle and full throttle, you'll find the right amount of air, get the proper air/fuel ratio, and the engine will start.

Starting with full throttle works okay too, but I've found that sometimes this is too much air and/or leads to high RPMs just after start if you don't pull it back quick enough. That's why I start at near idle throttle and just keep opening it until the engine starts. I also have dual P-mags, and I've never had a problem starting when hot.

I read about this technique in an article last year, but I can't find the original source anymore.

 

[steveKs.]

I leave mixture in idle cutoff and full throttle. I don't boost a hot engine. When she catches, push mixture forward and throttle back.

I am installing a sniffle valve. I always get a hot start but the engine is loaded up for a few seconds before it clears all the fuel. I think the sniffle valve will cure this.

 

[ShannonEvans]

hot start

The guys are pretty much correct. However, on my Super III Beech, I had a little trouble when very hot this summer. found that
1)slight throttle
2)full rich mix
3)boost pump 1sec
4)mix lean
5)throttle 2/3 full
6)Crank & when it grabs slowly feed in mixture
7)pull throttle to idle

Worked best. Seems a little more throttle helped

Shannon Evans
N5650S

 

[osxuser]

Jeeze, that complicates things a lot.

1. Mixture ICO
2. Throttle 1/2 open
3. Crank till it fires
4. Slowly feed in mixture and retard throttle

Works like a charm, Lycoming, Continental, fours, sixes, everything. I don't get the whole mixture ICO, pump on, pump off part.... that would do something on the Continental sixes with the vapor return line, but doesn't do squat on a non-purge valved lycoming....

 

[RV7Guy]

Idle cutoff?

I leave mixture in idle cutoff and full throttle. I don't boost a hot engine. When she catches, push mixture forward and throttle back.

Idle cutoff??? Do you have a Turbine in yours. Got Idle cutoffs in the turbines I fly!!

 

[RV7Guy]

Careful!!!!

A couple of more things.

Know the approximate throttle setting for 1000-1200 rpm. Use that and DO NOT GO ABOVE THAT for hot start procedures. You don't need it and for TD models you could have an issue if you don't have the stick all the way back. I saw a guy start his with this procedure and didn't have the stick all the way back. When the engine lit the tail came up and he nearly got the prop. He was carrying to much throttle. He was fortunate to get the throttle off before the prop hit.

A sniffle valve isn't needed. One more piece of complexity.

Trust me on this guys. It is not unusual for us in AZ to fly at 106 degrees or more temp. I've never had a problem with this procedure. You only need to work on the timing to get the second time it fires and the mixture in quickly and get the throttle out quickly.

 

[David-aviator]

....It is not unusual for us in AZ to fly at 106 degrees or more temp......

Lots of good info here as this neophyte moves on to a Barrett IO360.

One more time, Darwin, what oil cooler are you using? I know it works and I don't want to screw around with oil cooling in the hot summer around Missouri.

 

[RV7Guy]

More info

Hi David,

Good to hear from you. I will be having the Barrett team build me a fire breathing monster for my new project.

I am using a Stewart Warner 8432R Dual Pass oil cooler from Pacific Oil Coolers. It is pricey but well worth the money. Can't remember the exact price. Pacific is great to work with. I have not had any oil temp issues from day one. The other day I took off in the afternoon to fly to work. It was 107 degrees. Even in a 1200 fpm climb I only hit 205 for a short time. In cruise at 8500 OAT of 78 I was running 185 oil temp.

The cooler is baffle mounted behind the #4.

Good luck.

Lots of good info here as this neophyte moves on to a Barrett IO360.

One more time, Darwin, what oil cooler are you using? I know it works and I don't want to screw around with oil cooling in the hot summer around Missouri.

 

[dicer]

Just curious what everyone is talking about. No matter what fuel delivery system is used. Idle cut off means zero fuel flow. It would be a bit hard for it to run and start with zero fuel. In my old cessna 150 and 172 flying days, we started it the same all the time hot or cold. I never in my life had used the primer. I'd pump the throttle.
Some of the large radial engines are started stricly on the primer and then mixture is brought in.
Has there been a problem with these engines blowing up not starting correctly?

 

[David-aviator]

Hi David,

Good to hear from you. I will be having the Barrett team build me a fire breathing monster for my new project.

I am using a Stewart Warner 8432R Dual Pass oil cooler from Pacific Oil Coolers. It is pricey but well worth the money. Can't remember the exact price. Pacific is great to work with. I have not had any oil temp issues from day one. The other day I took off in the afternoon to fly to work. It was 107 degrees. Even in a 1200 fpm climb I only hit 205 for a short time. In cruise at 8500 OAT of 78 I was running 185 oil temp.

The cooler is baffle mounted behind the #4.

Good luck.

Outstanding! I've been zero-ing in on that cooler. Dan the man says the same thing, go dual bypass early.

Back to this thread, the AFP system comes with a purge valve. Anyone here using the device? I get the drift most do not have it. The engine I am getting comes with it and a sniffle valve.

P.S. I had a tour of the Barrett skunk works in Tulsa this past week....very interesting. I was most impressed with the computer that provided data to balance a crank shaft. This is an FAA approved process. A neighbor reported a ride in a friend's Cherokee with a Barrett OH'd engine, it was the smoothest Lycoming he ever experienced. (Coming off the 6 cylinder Subaru, it will be interesting to see just how smooth that is. )

 

[David-aviator]

Just curious what everyone is talking about. No matter what fuel delivery system is used. Idle cut off means zero fuel flow. It would be a bit hard for it to run and start with zero fuel. In my old cessna 150 and 172 flying days, we started it the same all the time hot or cold. I never in my life had used the primer. I'd pump the throttle.
Some of the large radial engines are started stricly on the primer and then mixture is brought in.
Has there been a problem with these engines blowing up not starting correctly?

Bob,

You are talking about an engine with a carb, they are talking about fuel injection and a hot engine causing vaporization in the plumbing to the injectors. That vaporized fuel can prevent fuel from getting the injectors and hence, special procedure to start a hot engine. It is not a big deal once you learn the technique.

Superior tried a carbon fiber plenum to save weight and sometimes a back fire with pooled fuel in the plenum would cause them to crack, I don't think any engines blew up. The sniffer valve is designed to allow that pooled fuel after shut down to drain out. (Larry Vetterman told me don't let it drip on my red hot exhaust pipes. ) The new Superior plenum is metal.

 

[DanH]

Throttle cracked for 1000 RPM or less, mixture in ICO. Start cranking, ease the mixture forward sloooowly.

The above assumes a current tech starter and battery, and a good spark.

I do not think nice thoughts when I hear any engine start with a big burst of RPM. Might want to reconsider some of those techniques requiring full throttle to crank.

 

[billpilot1]

When does it transition from hot back to cold?

At what point does the engine transition back to a cold start. I've got an XP IO 360 that I only have 40 hours on. Still working on the hot start. All this advice is great, and I will give it a try. But the other day, I flew in for some radio work, and about 3 hours later when I went to start it, I treated it as a cold start, and that was wrong. OUtside temp about 75 degrees. How do I know when to do a hot vs go back to a cold start? Any advice on this! Thanks in advance for your help.
Bill

 

[roadrunner20]

Superior tried a carbon fiber plenum to save weight and sometimes a back fire with pooled fuel in the plenum would cause them to crack, I don't think any engines blew up. The sniffer valve is designed to allow that pooled fuel after shut down to drain out. (Larry Vetterman told me don't let it drip on my red hot exhaust pipes. ) The new Superior plenum is metal.

I had the Superior forward induction with the ryton sump and sniffle valve.
I've since replaced it with the new aluminum sump which added 4lbs up front. I needed extra weight up front as I was turning a 3-blade Catto.

My hot start procedure:
Idle cutoff
No prime
Very little throttle(1/8")
Mixture on first fire.
Adjust throttle.

 

[osxuser]

Darwin... Idle Cutoff or ICO is an industry wide term... for all pistons i've ever worked on. I'd imagine turbines are the same, but I don't have any real experience there .

1/2 throttle works fine for everything i've ever done, including taildraggers. But yeah you do have to be on top of it, and getting the throttle out more quickly than on, say, a piper arrow. Cracking the throttle 1/8" will just mean you'll have to crank longer before it will fire, could be an acceptable compromise for people, I prefer to be easier on my starter, but that means I take the chance of sticking the airplane on it's nose if I don't pull the throttle back to idle.

 

[DanH]

Cracking the throttle 1/8" will just mean you'll have to crank longer before it will fire, could be an acceptable compromise for people, I prefer to be easier on my starter, but that means I take the chance of sticking the airplane on it's nose if I don't pull the throttle back to idle.

The compromise is between being easier on your starter and easier on your connecting rod big end bearings....if in fact it bothers the starter at all.

 

[kcameron]

Cracking the throttle 1/8" will just mean you'll have to crank longer before it will fire

I disagree with that. The point of cracking the throttle (instead of leaving it at the idle stop) is to allow more air flow. The extra air is needed to counteract the over-rich mixture caused by pooled fuel in the intake. If you watch your manifold pressure gauge, you'll see that cracking the throttle allows the manifold pressure to remain at ambient during cranking. Opening the throttle further doesn't increase the manifold pressure therefore no additional air flow and no reduction in start time.

My experiments show that my IO-360 is always rich during a hot start and that the engine starts just as quickly with the throttle cracked as it does with it opened further.

 

[osxuser]

I'm sure that the MP might be equal, but you can't realistically argue that more air (or less resistance to the air) wouldn't get the mixture combustible faster. There is no scientific way to test cranking time however. Either way will work in the end.

In some engine configurations it may not make an APPRECIABLE difference, but the procedure I outline works for every FI aircraft engine I've ever started, including every model of Continental IO, TSIO 3xx, 4xx, 5xx series. And most lycoming IO-320, 360, 540's including turbo and normally aspirated.

 

[DanH]

I'm sure that the MP might be equal, but you can't realistically argue that more air (or less resistance to the air) wouldn't get the mixture combustible faster.

Sure, but the argument is moot. Like the man said, MP at ambient means no additional air.

In some engine configurations it may not make an APPRECIABLE difference, but the procedure I outline works for every FI aircraft engine I've ever started......

Nobody is saying your proceedure doesn't work. The issue is lighting it off with a big burst of RPM and no oil pressure.

I'll bet you don't hold the throttle halfway to the floor when you start your car <g>

 

[roadrunner20]

BTW, my hot start with cracking the throttle 1/8", is what the manufacturer(Superior) recommends. I followed their instructions and there is no demand on my starter. It always start < 1 turn.

 

[billpilot1]

I'll ask it again!

Can someone tell me when it becomes a hot start as opposed to a cold start. After being shut down for 3 hours in 75 degree weather, I should have treated it as a hot start! Is there some indicator? Rule of thumb! ???
Thanks
Bill

 

[RV8N]

So... is this going to be the new "primer wars"?

Karl

 

[osxuser]

Sure, but the argument is moot. Like the man said, MP at ambient means no additional air.



Nobody is saying your proceedure doesn't work. The issue is lighting it off with a big burst of RPM and no oil pressure.

Oh, well if you retard at the first pop, the RPM never goes beyond normal idle... tomato vs. tomauto....

 

[kcameron]

Can someone tell me when it becomes a hot start as opposed to a cold start. After being shut down for 3 hours in 75 degree weather, I should have treated it as a hot start! Is there some indicator? Rule of thumb! ???
Thanks
Bill

Probably no answer because no one has a rule of thumb? If they're like me, restarting after multi-hour stop is rare enough that they haven't gathered enough data points to really know where to draw the line.

My approach is to use the hot start procedure if I've already flown that day except in the rare case that it's really been a long time (say 5 hours or more?) since I shut it down. The theory is that, if the pooled fuel has evaporated and the hot-start procedure results in an over-lean condition, it's instantly correctable by a quick shot of boost pump and mixture lever. On the other hand, erring by adding fuel to an already over-rich state can add a lot of cranking time.

 

[ao.frog]

Does a sniffle valve change things?

Hi.

Thanks for alot of inputs on this tread folks.
I've learned alot!

The answers have made me wonder if an installed sniffle valve changes things? Maybe that makes the hotstart procedure different from an injected engine without one?

Also, it'd be really nice to know if anyone has a rule of thumb regarding when a hot start is a hotstart or a cold start?
Maybe it can be as simple as placing your hand on the cylinders?
If you can keep it there: cold start?
If not: hot start?

I've always learned that if you can keep your hand somewhere for more than a few sec's, then the temp are above 60* Celcius...

Thanks.

 

[rzbill]

We forget so easily

I'll bet you don't hold the throttle halfway to the floor when you start your car <g>

Have we all been driving EFI cars long enough to forget what it was like to start a flooded mechanically injected or carb'ed car? It was (or is, if you have one) SOP to mash the pedal to correct a flooded condition.

I'm not buying the supposition that cracked throttle will correct richness as quickly as WOT. Especially if you have a RSA-5 with a scratched and/or leaky mixture gate valve. It doesn't take much fuel to compensate for the air from cracked throttle. I've seen enough leaky RSA-5s to just go with the assumption that all leak.

I agree with Stephen that deft throttle work can quickly start the engine without a rage of rpm. Even so, if the engine is hot, it was by definition recently pressurized with oil so there should be a good film still in the mains and big ends. Spam can batteries are usually the weak link for me, so I like to "get er done" before that thing quits.

 

[osxuser]

Have we all been driving EFI cars long enough to forget what it was like to start a flooded mechanically injected or carb'ed car? It was (or is, if you have one) SOP to mash the pedal to correct a flooded condition.

I have a '74 Dodge Dart, and thats how I had to hot start it. In fact if I didn't, I'd be cranking for eternity.

 

[Steve Brown]

This one

Jeeze, that complicates things a lot.

1. Mixture ICO
2. Throttle 1/2 open
3. Crank till it fires
4. Slowly feed in mixture and retard throttle
........

This is the one I use as well. Feeding in mixture while retarding throttle, while releasing the start key/button is a handful, but it works.

Sometimes I'll start with full throttle.

 

[David-aviator]

No one has yet mentioned using the purge valve. Is anyone spun up on its use? I believe it is mechanically opened to allowed the boost pump to pump fresh cool fuel into the injection lines. I guess that's all well and good so long as the plenum has no fuel in it. In other words it seems the sniffle valve would be a cousin to the purge valve in operation.

 

[AlexPeterson]

Have we all been driving EFI cars long enough to forget what it was like to start a flooded mechanically injected or carb'ed car? It was (or is, if you have one) SOP to mash the pedal to correct a flooded condition.

SNIP

Yes, it was SOP to go full throttle on those old cars to clear a flooded condition. However, it was to force the choke open (they had a linkage such that full throttle opened the choke, at least part way). If the MAP is ambient when cranking at partial throttle, you can't get more air in by going full throttle, as others have already said.

No one has yet mentioned using the purge valve. Is anyone spun up on its use? I believe it is mechanically opened to allowed the boost pump to pump fresh cool fuel into the injection lines. I guess that's all well and good so long as the plenum has no fuel in it. In other words it seems the sniffle valve would be a cousin to the purge valve in operation.

I have a purge valve, but I believe its main benefit is not in circulating cool fuel through the system pre-hot start. It is in preventing fuel from puking into the engine after shutdown. Only a tiny amount can still go in the engine, specifically that which is downstream of the purge valve, which is attached to the flow divider.

A few weeks ago I got to the hangar and noted some blue staining on the floor under the engine. Uh-oh, that never happened before. I got a flashlight and looked up inside, and could see fuel had dripped from the small hole in the FAB which is inside the filter (yes, I have another hole outside the filter). Hmmm. I then noticed that the purge valve had been pushed in. I remembered doing this to help a passenger egress on the previous flight. Most px's get out ok without it, but this time for whatever reason I needed to push it in. So, fuel barfed into the engine after shutdown, and some made it to the ground. Does it really matter? Don't know.

I do use the purge valve pre hot starts for maybe 10 seconds, to ensure fumes are out and relatively cool fuel is in. Then, 1/4 throttle, mixture ICO, then slowly in it catches. Seems to consistently take about 8 blades to fire, but quite reliably so. I've been too chicken to experiment with alternate hot start methods!

 

[rzbill]

OK, so we agree to disagree.

Yes, it was SOP to go full throttle on those old cars to clear a flooded condition. However, it was to force the choke open (they had a linkage such that full throttle opened the choke, at least part way). If the MAP is ambient when cranking at partial throttle, you can't get more air in by going full throttle, as others have already said.

Point taken on a flooded COLD engine and closed choke, but on the flip side I have land vehicles without chokes that benefit just as well from WOT for flooded start.

I understand the point about MAP, but there must be another factor at play because cracked throttle flood correction does not fit my experience.

 

[ao.frog]

Here's what I've found...

Hi all.

Thanks for all the inputs to my question: how to hot start a IO-360 with no purge valve.

Over the weekend, I hot-started my engine for the first time. I did 4 hot-starts total and every time the engine started without problems.
Before every hot-start, the engine had been sitting on the ground with the oilcooler door open for approx 30 minutes. The OAT was 10-14* Celcius.

Before I decided on a hot-start procedure, I sent an e-mail to Bill Peterson at Superior. He has been providing superb customer service for me all the time and here's what he recommended (and what I used):

"If the engine is hot, skip the high boost pump prime if there's more than 15 psi of fuel pressure.
Leave the mixture at idle cut off and crack the throttle and engage the starter. Rich when engine fires.

It usually starts but if it doesn't, go with mixture full rich and boost pump on until about 25 psi, then boost pump off, mixture idle cut off, throttle cracked and engage starter."

I've found that to achive 25 PSI fuelpress takes about a second or less.

I realize that only 4 hot-starts maybe too little to establish a firm ground on, but it has worked very nice for me so far, so this is how I'm going to do hot-starts until further.
Also, it feels alittle bit better to have the throttle at only 1 cm open...