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PW4000-94 and CF6-80C2 Comparison

Posted: Wed May 06, 2020 3:02 am
by LH707330
The other thread about the DC10 engines and the 747 wing tank capacities got me thinking about the era of the "commodity engines," where every widebody frame had either 2, 3, or 4 of whatever the highest-thrust engine of the time was. In comparing the PW4000-94 and the CF6-80C2, I saw they have similar thrust, OPR, BPR, TSFC, and weight, but their layout is quite different. Compare here:

PW: 1F 4 LPC 11 HPC 2 HPT 4 LPT 153.6 in (390 cm)
GE: 1F 4 LPC 14 HPC 2 HPT 5 LPT length 168 in (427 cm)

Why is it that GE built so many more stages into their engine and made it so much longer in the process? It was obviously the best-selling engine of that generation, so they were doing something right, but what?

https://en.wikipedia.org/wiki/Pratt_%26_Whitney_PW4000
https://en.wikipedia.org/wiki/General_E ... 6#CF6-80C2

Re: PW4000-94 and CF6-80C2 Comparison

Posted: Wed May 06, 2020 12:09 pm
by Wacker1000
LH707330 wrote:
Why is it that GE built so many more stages into their engine and made it so much longer in the process? It was obviously the best-selling engine of that generation, so they were doing something right, but what?


Its what makes it the 4 time world discus throwing champion.

Re: PW4000-94 and CF6-80C2 Comparison

Posted: Wed May 06, 2020 1:59 pm
by 747classic
See this old thread : viewtopic.php?t=771335

Re: PW4000-94 and CF6-80C2 Comparison

Posted: Wed May 06, 2020 11:47 pm
by LH707330
Wacker1000 wrote:
LH707330 wrote:
Why is it that GE built so many more stages into their engine and made it so much longer in the process? It was obviously the best-selling engine of that generation, so they were doing something right, but what?


Its what makes it the 4 time world discus throwing champion.

Ha ha, clever.

747classic wrote:
See this old thread : viewtopic.php?t=771335

Thanks for the link, that was a good read. The tl;dr of that seems to be that the GE gets better temp margins at high-thrust settings, marginally better TSFC at takeoff, and slower deterioration, but outside of that they seem pretty similar.

Re: PW4000-94 and CF6-80C2 Comparison

Posted: Fri May 08, 2020 6:00 am
by 747classic
I found this article (2017) about the maintenance facilities of the large civil engine OEM''s and MRO's.
A nice comparison between the numbers built of each engine type

Clearly visible is that PW is only No 3 in the wide body engine market , after GE and RR.
The battle between PW and GE seems to be lost by PW during the PW4000/CF6-80C2/E contest and finished off by GE with the introduction of the large GE90-94/110B/115 and the failure of the PW4098 engine.
RR became a good second, but now has serious issues with a large share of it's engines.

See : https://www.ajw-group.com/storage/downl ... mmerce.pdf

Re: PW4000-94 and CF6-80C2 Comparison

Posted: Fri May 08, 2020 8:00 pm
by 767333ER
Well the CF6 ended up being the most powerful of those level of engines and it also is louder than the PW4000-94 which makes sense. The most powerful engine in this case is simply the biggest one. The CF6 basically began as the CF6 and got changed here and there every time there was the need. The PW4000 as an evolution of the JT9D so its lineage is a little longer. A combination of this and the overall engineering goals would likely have lead to different sizes.
747classic wrote:
I found this article (2017) about the maintenance facilities of the large civil engine OEM''s and MRO's.
A nice comparison between the numbers built of each engine type

Clearly visible is that PW is only No 3 in the wide body engine market , after GE and RR.
The battle between PW and GE seems to be lost by PW during the PW4000/CF6-80C2/E contest and finished off by GE with the introduction of the large GE90-94/110B/115 and the failure of the PW4098 engine.
RR became a good second, but now has serious issues with a large share of it's engines.

See : https://www.ajw-group.com/storage/downl ... mmerce.pdf

The battle was somewhat lost looking at the PW4000-94 vs the CF6-80C2, but both were vastly more capable engines than the RB211 at that point which is why the RB211 failed to sell on many 767s and was not offered on the 747-400ER. PW had an opportunity to build on their moderate success there but they squandered it. Then RR came out with the Trent and PW could not secure a second place.

Re: PW4000-94 and CF6-80C2 Comparison

Posted: Fri May 08, 2020 11:15 pm
by LH707330
767333ER wrote:
Well the CF6 ended up being the most powerful of those level of engines and it also is louder than the PW4000-94 which makes sense. The most powerful engine in this case is simply the biggest one. The CF6 basically began as the CF6 and got changed here and there every time there was the need. The PW4000 as an evolution of the JT9D so its lineage is a little longer. A combination of this and the overall engineering goals would likely have lead to different sizes.
747classic wrote:
I found this article (2017) about the maintenance facilities of the large civil engine OEM''s and MRO's.
A nice comparison between the numbers built of each engine type

Clearly visible is that PW is only No 3 in the wide body engine market , after GE and RR.
The battle between PW and GE seems to be lost by PW during the PW4000/CF6-80C2/E contest and finished off by GE with the introduction of the large GE90-94/110B/115 and the failure of the PW4098 engine.
RR became a good second, but now has serious issues with a large share of it's engines.

See : https://www.ajw-group.com/storage/downl ... mmerce.pdf

The battle was somewhat lost looking at the PW4000-94 vs the CF6-80C2, but both were vastly more capable engines than the RB211 at that point which is why the RB211 failed to sell on many 767s and was not offered on the 747-400ER. PW had an opportunity to build on their moderate success there but they squandered it. Then RR came out with the Trent and PW could not secure a second place.

Yeah, the 211-524G/H was definitely the worst of that generation: it was heavier and burned more fuel. PW and GE definitely sharpened their pencils relative to the earlier generation, where it seems the 524D was the high point. I'm wondering how exactly PW managed to drop the ball on the 4000-94, maybe it was the support area where buyers of the JT9D got frustrated. Several longtime PW buyers defected to GE on that generation, like ANA and JAL. Then you have oddballs like Delta who bought CF6-80As, then PW4000-94, then CF6-80C2 on their 767s....