More power from a 2.5 NA

[Greg S]

It's true! More power!

My anemic little 2.5 NA (Naturally Asphyxiated) diesel powered LR 90 has noticeably more power after taking it to Minute Muffler and getting a blown exhaust seal repaired.

For a few months now I've experienced increasing exhaust noise from the engine bay. I was convinced it was the head to manifold gasket, even more convinced when I changed it, by the loose nuts and slight evidence of blow-by. Unfortunately I still had excessive noise afterwards. Stuffing a rag in the tail pipe quickly showed a leak at the down pipe connection at the manifold. Off to the repair shop here in Duncan where they got me fixed up. Of course, once they hoisted the 90 it was evident the muffler was past its "best before date"; actually it had a big split down its side. They fixed the leak at the down pipe, installed a new muffler and re-secured the failed pipe hangers.

I don't fully understand the physics of it, but there is no doubt about it. The little 2.5 diesel has more power/speed up hills now. I guess I can bend my mind around the idea of mass and inertia of an exhaust pulse from one cylinder "drawing" the gasses from the next contributing to more power instead of just leaking to atmosphere at a failed joint. Or maybe Olive is just happier now that she has had some TLC.

Of note: Minute Muffler in Duncan is where Dixon of Rock Island 4X4 (formerly known as Rock Island Rovers) has service and repair work done on the Land Rovers he imports. They now have some hands-on knowledge of working on Land Rovers.

[Arcades]

Contrary to some people's ideas, engines are usually designed for some back pressure from the exhaust... They don't run we'll unless they have it...

[Crs]

^Good to know.
My entire knowledge of back pressure comes from the banana scene in Beverley Hills Cop. :mrgreen:

[Arcades]

^Good to know.
My entire knowledge of back pressure comes from the banana scene in Beverley Hills Cop.

< insert Eddie Murphy's laugh here >

:)

[Dave_F]

"speed up hills now"
:laughing5: - :laughing6: - :laughing7: - :laughing8: - :laughing9: - :lol:

[discojonny]

my understanding is that diesels do not need back pressure to perform properly, that is for gas engines. my guess is you are able to give it a little more throttle without the noise to deter you.

[Greg S]

my understanding is that diesels do not need back pressure to perform properly, that is for gas engines. my guess is you are able to give it a little more throttle without the noise to deter you.

More throttle? I thought there was only two settings on it. Idle and pinned to the floor. :lol:

Maybe I could cut out a section of the floorboard below the skinny pedal so it goes farther down. LOL

My understanding is the low pressure created behind an advancing pulse of exhaust from one cylinder helps draw the exhaust charge from the next cylinder. A leak prevents that low pressure in advance of each subsequent firing.

Another thing I notice is there is a much smaller white/blue cloud when I start it up in the morning. I'm not entirely sure how to explain that one.

[davran]

Looks like no back pressure is best for turbo-diesels, but not normally aspirated ones:

http://www.myturbodiesel.com/1000q/turb ... rboexhaust