exhaust ports

[Terry]

I picked up this F-82 photo from Plane a day this morning. It shows 2 exhaust ports per cylinder. I have several other photos of both the F-82 and P-82 which all have 1 port per cylinder. Anyone know why this is?

[stansdds]

That's an F-82E, it had a different exhaust stack arrangement than the P-82B, but the engines were still Allison V-1710's.

[magoo]

Allison 1710's were a four valve per cylinder mill. Each exhaust valve benefitted from an individual port. Earlier exhaust stacks would relieve two ports each, later tech extractor types were setup one each per port.

P-40's and early P-51 series are good visual example to compare with the F-82. Another parrallel comparison is looking at a Merlin powered Spitfire Mk.I versus a Mk.IX.

Aviation hot-rodding.

[Terry]

Allison 1710's were a four valve per cylinder mill. Each exhaust valve benefitted from an individual port. Earlier exhaust stacks would relieve two ports each, later tech extractor types were setup one each per port.

P-40's and early P-51 series are good visual example to compare with the F-82. Another parrallel comparison is looking at a Merlin powered Spitfire Mk.I versus a Mk.IX.

Aviation hot-rodding.

That's the answer I was looking for. Thanks!:salute:

[Volker Böhme]

Hi,

yep, the early Spits had 2 cylinders per exhaust port while the Bf-109 had 1. Each engine manufacturer came to a slightly different solution, whatever turned out to work better.

Best regards,
Volker

[Sunny9850]

Even on the 1710 there are different configurations, depending on the mount it was bolted to.
On some you do have a 2 in 1 collector for each of the cylinders.
The theory being that the two ports are equalized in flow speed by doing so.
Joe&Pat Yancey's engine shop is based at my home base L67 and about every other week one Allison or another is running on the test stand...exhaust configurations galore.

Cheers
Stefan

[Tom Clayton]

...about every other week one Allison or another is running on the test stand...exhaust configurations galore.

Cheers
Stefan

You really need to get us some video! :applause:

[wombat666]

Siamesed exhaust ports have long been used in competition car engines, not common today but the Alfa Romeo 158/159 and Maserati's 8CLT used dual 8 into 1 systems on their blown straight 8 Grand Prix cars, with Maserati following the same pattern with their 4CLT straight 4 efforts.
REPCO turned out an experimental 3 litre V8 around 1969/1970(?) sporting exhaust ports on the inside and outside of each cylinder head.
Never used for obvious exhaust system problems!

[Sunny9850]

Will do Tom, next time Joe has the rig outside for a break-in run.

Cheers
Stefan