BMW 801D engine in the FW-190... Some Questions

[contrails16]

Hi all! So I am writing this just because I thought I knew a decent amount about the 190, but today I found some sources saying that the 801D engine ran only on 100 octane fuel? I'm just a little confused as I always thought it ran off of the 87 octane B-4 gas. Another question I would like to ask while posting this is more of just to verify my previous knowledge. I know that early versions of the FW-190 prior to the A5 had engine overheating issues, and that this could lead to the engine being perceived as unreliable, but didn't the A5 and onward have more space in the engine bay to allow adequate cooling of the rear cylinders? Thank you all for your time and knowledge

 

[Hardrada55]

I thought BMW 801A and C ran off 87 octane B4 and 801D ran off of 94-96 octane C3? And I thought the Germans moved the firewall forward for center of gravity reasons, though the cooling might have been a nice addition, along with the ability to mount MG 131. Can't wait to learn more.

 

[contrails16]

I thought BMW 801A and C ran off 87 octane B4 and 801D ran off of 94-96 octane C3? And I thought the Germans moved the firewall forward for center of gravity reasons, though the cooling might have been a nice addition, along with the ability to mount MG 131.

I am going to be honest, I am not sure, I am starting to get the feeling that a lot of websites are spreading misinformation about the engine sadly, which is why I came here in hopes of finding the truth.

 

[MIflyer]

Can you read German?

 

[contrails16]

Can you read German?

sadly no, but I may have some twitter followers from Germany that are willing to help... I hope LOL

 

[contrails16]

Can you read German?

Sadly one of my twitter followers was not able to find specific octane information for the 801 D-2

 

[mad_max]

190's needed C3 fuel. DB's used C3 in the 601N series and 87 in the rest.

A8 translated handbook - go to part 7 on Engine Operating and Fuel Supply System page 55.




Data plate from 19-8-1943



A-2 through A-6 - paragraph #7 states C3

 

[DarrenW]

I think it's pretty well established that the BMW 801D ran on C3 fuel but there may have been exceptions to this.

This is an interesting document which shows the results of testing performed on various samples of fuel taken from downed German aircraft. Discussion of C3 fuel starts on page 9. The listed octane numbers show us how it rated using allied testing procedures. It looks like the lean rating hovered somewhere in the mid 90s....

 

[Deleted member 68059]

I`d be interested to hear where the source for contention is on this, its pretty well established.

The only times where the 801 was on B4, were versions 801 C or earlier, and later on as an emergency measure when there wasnt
any C3 about, in operations many engines were de-rated to use whatever was on hand (i.e lowering the boost). However as far
as factory specs go, the 801 D onwards was definetly not specified for B4.

Its pretty easy to differentiate BMW 801 A,B,C to D versions as the A,B,C on B4 are all limited to 1.32ata manifold pressure. These were typically bomber engines.

C3 came in with the D version: (this is in English as its from the British Intelligence file on the 801)

As far as 801 unreliability, there are many aspects to that, and there was a lot of work reworking the exhaust pipes etc and improving the cooling
as was the case for all air-cooled engines. However, most of the problems were metallurgical in nature, and indeed the 801 was
deeply unreliable until somewhere around late 1942. There isnt really a "cut off date" for that, the issues were always ongoing to various degrees.

 

[contrails16]

Thank you everyone for taking the time to answer this for me. I can't remember where I read the 801D ran B4, perhaps it may have been me incorrectly associating A,B,C variants with the D. I think I was also shocked to find out that the 801D was meant for C3 fuel, as when it was introduced in 1942, I thought the Germans were struggling to acquire such octane fuel. Thank you everyone once again. Another question I have for you knowledgeable bunch is in short, what did BMW and Focke Wulf do to fix the overheating issue on the FW-190's equipped with earlier engines? Thanks

 

[DarrenW]

Another question I have for you knowledgeable bunch is in short, what did BMW and Focke Wulf do to fix the overheating issue on the FW-190's equipped with earlier engines?

I believe that moving the engine mounting 15 cm further forward and adding larger cooling slots in the A-5 model did improve engine cooling.

 

[contrails16]

I believe that moving the engine mounting 15 cm further forward and adding larger cooling slots in the A-5 model did improve engine cooling.

View attachment 592280

Good that's what I thought it was