Kevin Eldredge Interview: What Happened At The Reno Air Races 2008

[beeroosterm]

Why the hell not? As a matter of fact, most engines do not have them - haven't for decades...

[SlamDuncDrummer]

@beeroosterm - I'm not aware of any (non-turbine) engine that produces more than 2000hp without a magneto. I could be wrong but am fairly sure.

[beeroosterm]

@SlamDuncDrummer Did you look?

[beeroosterm]

Respond to this video...  Took me one minute to locate "Tsunami", an unlimited racer with electronic ignition in its Merlin engine. Can't find the hp at this time, but I'm betting it was way over 2000...

[SlamDuncDrummer]

@beeroosterm - Rolls Royce Merlin and Rolls-Royce Griffon both use magnetos. Base Merlin is in the 1500ph range and Griffon is about 1700hp range.

With heavy modifications, either engine puts out well in excess of 3,000ph.

What was your point about electronic ignition? Magnetos are used with electronic ignitions all the time, specifically in aircraft for increased reliably and to decrease weight.

Tsunami has two (2) magnetos.

I actually did read.

[beeroosterm]

@SlamDuncDrummer "Tsunami" had an electronic ignition, specifically mentioned in the article I found. And I had no real point other than to counter the comment that you can't live with or without magnetos. People have been living without them for a long time. And they are indeed a pain in the ass; heavy, and a PIA to deal with. I don't really care...

[SlamDuncDrummer]

@beeroosterm - on the Tsunami website and in the WIKI it clearly states that it has magnetos. Magnetos are run with electronic ignition systems all the time. In fact the WIKI states that Tsunami specifically chose magnetos for weight reduction among other reasons.

[beeroosterm]

@SlamDuncDrummer Here's a quote from the website "A lot of changes had been made. The wing had been moved back nine inches; a major rework of the airframe. Many other things had changed, including the moving the center of gravity, electronic ignition and tail changes." From Warbired aeropress

[SlamDuncDrummer]

@beeroosterm - my simple point was that magnetos are run with electronic ignitions all the time, especially in aviation.

[beeroosterm]

@SlamDuncDrummer Guess I'm a simpleton. I thought the entire point of using an electronic ignition was to eliminate the magneto/contact points setup. I've worked on them for years when restoring antique outboards, and they are a pain in the ass, with the contact points causing most of the problems.

[SlamDuncDrummer]

@beeroosterm - after doing a bit of research on this and talking to a few friends that tune Top Fuel cars and high horsepower, supercharged engines with a lot of compression on cars or aircraft, it appears that magnetos are required to get the longer duration, higher energy spark required to ignite the entire mixture.

For example; on a fuel car they are using a fuel pump that pumps 8 gallons of nitro per minute per cylinder. The magneto ignites all of this mixture leaving nothing behind.

[beeroosterm]

@SlamDuncDrummer Turbo/supercharged engines run with low-compression pistons/combustion chambers, as the blowers up the cylinder pressures well enough. As for Top Fuel cars, they force as much fuel as possible through the cylinders - to the point that the fuel is used as a coolant as well. They do not come close to burning all the fuel that is pushed through them - as anybody who stands anywhere near them can attest. You have to take a "nitro shower" when you get home after the races.

[SlamDuncDrummer]

@beeroosterm - I did a bit of reading and maybe you have an answer:

Nitro burns slower than gas but burns completely because it contains it's own oxygen atoms. While Nitro has lower energy density it can produce nearly 3 times more energy than gas or methanol. This is possible because Nitro contains its own oxygen atoms.

While nitro burns slower, it burns nearly 100% of the fuel. This is why you see massive header flames at night. The dual Magnetos are required to keep all that energy lit.

[SlamDuncDrummer]

@beeroosterm - I have been to a lot of top fuel events as a photographer for NHRA.com and have spent my time in between the trees and within 5 feet of the cars and I have never been sprayed with anything other than tiny tire pieces from the burn-out. Occasionally oil from an oil down but never nitro. My white lenses are typically black by the end of an event.

[SlamDuncDrummer]

@beeroosterm - it is my understanding that Supercharged engines allow an engine to sustain higher power levels at rest. I.E. cruise speeds at say 1,000 less RPM etc. They also allowed piston engines to be efficient at altitude. When an engine can be at rest (so to speak) during a race, this means that this engine will have a certain period of time where it can be pushed harder.

I would think that the combination of reliability and performance would be the reasons for the Magnetos.

[SlamDuncDrummer]

@beeroosterm - I actually reversed my notes on the first post and should have said low to medium compression engines not high compression. I think Top Fuel is 6:5:1 and the Supercharged Merlin is only 6:1.

[schlusselmensch]

Magnetos; Can't live with them, can't live without them.