## Top Fuel Pics

Please discuss here all your remarks and pose your questions about all racing series, except Formula One. Both technical and other questions about GP2, Touring cars, IRL, LMS, ...
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 are two things in this world that take no skill: 1. Spending other people’s money and 2. Dismissing an idea.

Joined: 2 Jan 2010

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?

Just shows you how ungodly terrifying nitromethane is.

When I was about 13 I went to the NHRA nationals in Ennis (just southeast of Dallas) with my dad and some friends. I was walking through the pits when one of the teams fired up their car. Of course, I'm standing right behind the thing and ended up with a face full of nitro exhaust. Horrid. You'd have to be like three inches from a regular car's exhaust to get the same kind of immediate burning eyes and closed up windpipe, and I was about twenty feet away. Nasty stuff.

But ever so fun. 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.
thearmofbarlow

Joined: 23 Feb 2012

They have revised the estimated horsepower from 8000 to 9500-10,000.
thearmofbarlow..Yeah it can really take your breath away. I love it.
There are two things in this world that take no skill: 1. Spending other people’s money and 2. Dismissing an idea.

Joined: 2 Jan 2010

@ thearmofbarlow:
When I was 16 I was gofer for a hometown top fueler -- wiping off the slicks, helping line up the car at the line, etc. One night at a little 1/8 mile strip in Mercer, PA I made the mistake of wearing my pride and joy -- a sheepskin-lined suede leather jacket. The fueler fired as I was pushing on a slick and I got a zoomie-load full in the chest. That beautiful jacket forever more had the consistency of cardboard.
Enzo Ferrari was a great man. But he was not a good man. -- Phil Hill
donskar

Joined: 3 Feb 2007
Location: Texas, USA

Plain-talk look at top-fueler-type engines from today's New York Times (technology mixed with push rods):

http://www.nytimes.com/2012/08/05/autom ... t.html?hpw
Enzo Ferrari was a great man. But he was not a good man. -- Phil Hill
donskar

Joined: 3 Feb 2007
Location: Texas, USA

strad wrote:How many times does that engine actually fire during those 3.8 seconds?

Just 506 revs in 3.8 seconds. So each cylinder only fires 253 times - do you replace the plugs for each run?

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?
richard_leeds

Joined: 15 Apr 2009
Location: UK

richard_leeds wrote:
strad wrote:do you replace the plugs for each run?

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.
countersteer

Joined: 28 Apr 2007
Location: Spring Hill, TN

richard_leeds wrote:
strad wrote:How many times does that engine actually fire during those 3.8 seconds?

Just 506 revs in 3.8 seconds. So each cylinder only fires 253 times - do you replace the plugs for each run?

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?

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.
"The question isn't who is going to let me; it's who is going to stop me."
flynfrog

Joined: 23 Mar 2006

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?
richard_leeds

Joined: 15 Apr 2009
Location: UK

richard_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?

http://www.hotrod.com/techarticles/engi ... ewall.html

Looking at this article its not just the valves but a full bottom end rebuild as well I think they reuse the crank.
"The question isn't who is going to let me; it's who is going to stop me."
flynfrog

Joined: 23 Mar 2006

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?

Pre-assembled sub-assemblies + well trained mechanics:

Scootin159

Joined: 6 Aug 2009

For some reason people are always tripped by the last statement in this video.
There are two things in this world that take no skill: 1. Spending other people’s money and 2. Dismissing an idea.

Joined: 2 Jan 2010

strad wrote:They have revised the estimated horsepower from 8000 to 9500-10,000.

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.

I think the HP numbers are BS fed to the viewing audience.

Brian
Last edited by hardingfv32 on Wed Aug 08, 2012 7:39 pm, edited 1 time in total.
hardingfv32

Joined: 3 Apr 2011

richard_leeds wrote:Also, how are the valves replaced in a 90 min turnaround?

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.

Brian
hardingfv32

Joined: 3 Apr 2011

hardingfv32 wrote:
strad wrote:They have revised the estimated horsepower from 8000 to 9500-10,000.

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.

I think the HP numbers are BS fed to the viewing audience.

Brian

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.
Ya know, all you ever wanna do is argue and try to pick stuff apart.
Have you ever been involved in drag racing?
There are two things in this world that take no skill: 1. Spending other people’s money and 2. Dismissing an idea.