Just shows you how ungodly terrifying nitromethane is.strad wrote:It comes from pumping nitromethane in and compressing it to near soild state before igniting it.
Something I have always found intersting is that yes a T/F engine turns from 7 to 8 thousand RPM, but a run only lasts 3.8 seconds...break out your calculators...How many times does that engine actually fire during those 3.8 seconds? Make your math simple,,call it 4 seconds and an average of 8000RPM. And THAT pushes you to over 300mph?
There's nothing quite like the sound and fury of a nitro powered car booming down a quarter mile. I might have to make the trip out there again this year. Just 506 revs in 3.8 seconds. So each cylinder only fires 253 times - do you replace the plugs for each run?strad wrote:How many times does that engine actually fire during those 3.8 seconds?
Actually, they're consumed on every run! Yes, melted away. They're pushing amps through the plugs on the order of a welder. Once the thing gets on full song it heats to the point that the mixture auto-ignites. That's why the shut it down with the fuel shut-off. Shutting off the ignition will do nothing at that point.richard_leeds wrote:strad wrote:do you replace the plugs for each run?
the plugs burn off at the 60 foot line. You not only replace the plugs but also the valves. Some where I have an awesome video of top fuel fuel injector at full tilt it looks like a fire hose.richard_leeds wrote:Just 506 revs in 3.8 seconds. So each cylinder only fires 253 times - do you replace the plugs for each run?strad wrote:How many times does that engine actually fire during those 3.8 seconds?
I'm amazed at how it is possible to force a gallon of fuel per second into the cylinders. I presume that is a gallon of fuel, there would be a much bigger volume of air:fuel mix? What's the volume at atmospheric pressure?
http://www.hotrod.com/techarticles/engi ... ewall.htmlrichard_leeds wrote:I'd expect the valve seating would be critical for maintaining the high compression, does that drop off towards the end of the run?
Also, how are the valves replaced in a 90 min turnaround? I guess the cylinder head is designed for a quick plug and play replacement, and you'd not have time to carefully use grinding paste for the valve and seating?
Pre-assembled sub-assemblies + well trained mechanics:richard_leeds wrote:Also, how are the valves replaced in a 90 min turnaround? I guess the cylinder head is designed for a quick plug and play replacement, and you'd not have time to carefully use grinding paste for the valve and seating?
It is a little odd, the HP numbers have been climbing at about 500 HP per season over the last few years while almost nothing has change. The nitro % has been fixed for many years. The engine is very restricted by the rules. You can not introduce a new part without sanction body approval. The sanction body has absolutely no interest in increases of performance.strad wrote:They have revised the estimated horsepower from 8000 to 9500-10,000.
Turnaround times were reduced to speed up the show. 75, 65, and 60 minutes as the rounds progress. As you work through the brackets running few pairs, you start to run out of races to fill the time gaps.richard_leeds wrote:Also, how are the valves replaced in a 90 min turnaround?
Well I wish I had recorded the Northwest Nationals for you. They have been saying 8000HP for ages Brian and so they worked it out mathematically and showed the formula.hardingfv32 wrote:It is a little odd, the HP numbers have been climbing at about 500 HP per season over the last few years while almost nothing has change. The nitro % has been fixed for many years. The engine is very restricted by the rules. You can not introduce a new part without sanction body approval. The sanction body has absolutely no interest in increases of performance.strad wrote:They have revised the estimated horsepower from 8000 to 9500-10,000.
I think the HP numbers are BS fed to the viewing audience.
Brian
