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Just so you know what kind of time spans we're talking about here. At 1000 rpms, it takes the crank .06 secs to make a revolution. If advance is at 10 degrees it's about 0.0017 seconds of explosion time we're talking about. At 6000 rpms, it would take 62 degrees of advance to allow that much time, but with the speed and heat being generate, total advance can only be little more than half of that.
------------------ 351W 89 Mustang GT Convertible [This message has been edited by jimberg (edited 06-14-2001).] |
jimberg....That's a lot of info, I had to read it twice to catch everything I missed the first time http://www.mustangworks.com/msgboard/smile.gif.
------------------ 1989 lx notch 89,000 miles bolt-ons,stock heads/cam 60'- 2.07, 8.90@78, 13.93@99 |
I just hope it's useful info. http://www.mustangworks.com/msgboard/biggrin.gif
------------------ 351W 89 Mustang GT Convertible |
Quote:
I had a shop teacher adamantly maintain that no engine could be revved past 6,000 rpm or so (yeah rite!) since his calculations were based on a steady state burn (gasoline), unfortunately he didn't any other variables in account when he did the math! For a high RPM engine, a small chamber with a good R/S ratio is desirable, along with a port/chamber design which promotes good fuel atomization/homogezination. a. a small chamber reduces the time it takes to burn the A/F mixture across the chamber b. a high r/s ratio creates more piston dwell time at TDC c. highly atomized and homoginized fuel tends to burn more rapidly. |
Right, the timing isn't linear for another very obvious reason. By compressing the gases faster at higher RPM you generate more heat which will cause detonation earlier and earlier.
------------------ 351W 89 Mustang GT Convertible |
jimberg - how is the timing being non-linear (advances with rpm) going to discourage detonation?
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Sorry. That was unclear. Advance in degrees can be linear in relation to rpms, but advance in an actual time interval would not be. e.g. The 0.0017 seconds in above example.
The faster you compress a gas, the more heat will be generated since there is less time to dissipate the heat. This extra heat will add to the potential for detonation. ------------------ 351W 89 Mustang GT Convertible |
I think jimberg's been readin a lotta physics lately. http://www.mustangworks.com/msgboard/biggrin.gif
Mach 1 TFS added me to the payroll 3 months ago, they keep telling me the check's in the mail, but for some reason, it always get's lost? http://www.mustangworks.com/msgboard/tongue.gif |
Yeah, the old "check is in the mail story"...heard it a hundred times myself...lol.
I think Jimberg is confusing himself...... ------------------ 1993 GT/AOD '93 Mustang GT |
Trick Flows it is....
Thanks! ------------------ Robert 91GT; 88 ASC McLaren #709 |
Re: My head choice dilema...
Have you thought about AFR heads? Edelbrock is an excellent choice as well!!
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Re: My head choice dilema...
This thread is 3 1/2 years old. Whatever he decided, I'm sure its a done deal my now. :lol:
Andy |
Re: My head choice dilema...
I use TFTW heads and couldn't be happier. I have enough low end torque to smoke the tires with a C-4/3.25. I don't know what I would do with anymore low end torque. One other good thing about the TFTW, is that they have a raised valve cover rim that allows using roller rockers with poly-locks and still be able to use stock height valve covers.
On the other hand, I've heard that the AFR 165 heads are "kick ass" in the torque and power department. I think I would have been just as happy with those too. Rev |
Re: My head choice dilema...
Another vote for TW's...
Man, do I love them! Especially w/ 3.73's, but my neighbors for some reason don't appreciate them nearly as much. :D |
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