914 low on power

[rhtrudder]

Having trouble with the 914 engine in my plane , on take off when the engine is in boost ,it starts to falter. Could it be the fuel a bit stale as the last time it ran OK but that was about 6 weeks ago The fuel is stored in a tank under ground and could be 12 weeks old and it runs OK in all the other engines on the farm Nothing else has changed since it ran 6 weeks ago and now its playing up ,can premium UL degrade it that time

 

 

[M61A1]

Sounds Ike the best place start looking. 6 weeks is a long time for PULP sitting in a vented tank.

 

 

[SDQDI]

I would have to agree with m6 on this, but also have a good look at the airbox and fittings as if it has a leak anywhere that could cause trouble with boost.

 

I also read somewhere lately about rubbers on carbies cracking but can't for the life of me remember where:scratching head:

 

But the fuel is the best place to start and easiest fix

 

 

[rhtrudder]

Drained all the fuel out and replaced with new from the servo , all fixed, how easy was that, goes to show pulp doesn't keep for long

 

 

[DrZoos]

This is well debated...many will say that 98 degrades to a lower octane then 95 over a period of weeks in unsuitable storage.

 

I know plenty of high performance bikes racing on 95 because 98 cant be trusted even straight from the servo....where as if they tune for 95 its usually pretty close

 

 

[eightyknots]

Drained all the fuel out and replaced with new from the servo , all fixed, how easy was that, goes to show pulp doesn't keep for long

Definition of PULP: a magazine or book printed on rough, low-quality paper made of wood pulp or rags, and usually containing sensational and lurid stories, articles, etc.

 

It sounds pretty bad. I would stick to the 95 because it retains its octane rating for much longer.

 

 

[Guest Maj Millard]

I used to run 98 in the 912 ULS ( 100 HP) but got a couple of bad batches...now I only run 95 exclusively as it is a lot more consistent .....had no dramas with 95..........Maj.....

 

 

[rhtrudder]

My 914 is fitted with a intercooler that has air directed through it via a scoop on the cowl , thanks to the previous owner, I always wondered what the air box temps were so I fitted a temp gauge off a engel fridge . the temps rarely go above ambient so if the intake charge is that low maybe I can run unleaded if detonation is a product of high intake temps

 

 

[AVOCET]

Definition of PULP: a magazine or book printed on rough, low-quality paper made of wood pulp or rags, and usually containing sensational and lurid stories, articles, etc.It sounds pretty bad. I would stick to the 95 because it retains its octane rating for much longer.

Have you any idea how long ?

Aprox .

 

 

[DrZoos]

95 seems safer if suitable on anecdotal evidence... which is all we have to go by

 

it could be worth contacting your fuel supplier to ask them specifically the differnce between octane degradation in 95

 

But for at least 10 years in competitive motor sport i have heard the same story over and over....

 

no problems with 95, lots of problems with 98

 

Mind you i have no knowledge of turbo applications...

 

In my experience running 450cc moto bikes i have had plenty of dramas with 98 and none with 95.... ever lots of popping and pinging with 98...and never missed a beat on 95

 

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