[DeTomaso] Compression Ratio Question

Ken Green kenn_green at yahoo.com
Fri Sep 21 23:16:22 EDT 2007


While the static compression will drop if the valves stay open longer, I don't think that implies the same happens at high RPM when VE may exceed 1 on a well designed engine.  If high RPM detonation is the problem (which I think Art suspected for his engine) you may be stuffing over 100% of the cylinder volume into the engine.
   
  Does anyone know if there are easy ways to detect high RPM detonation?  Seems like it would be a lot harder to detect than the obvious low RPM "ping".
   
  Ken

adin at frontier.net wrote:
  I think the term is "effective compression" or something. Overlap 
decreases the liklihood of detonation - let's see what Dan says - this 
is how we set up my alum. head 460.

MadDawg makes some good points . . .



Quoting Mad Dog Antenucci :

> Garth wrote;
>
> "Aluminum heads usually increase the likelyhood of deonation so 
> forget a high compression engine"............
>
> Wooooooooooooooooooooot?! I know you said your advise wasn't 
> worth 2-cents but I disagree with you buddy. ;-]>
>
> Didn't Bob's engine break?! ;-]>
>
> Detonation can be caused by allot of issues including going too 
> LEAN, incorrect timing blah-blah....and maybe I misunderstood DR. 
> DAN on this point but if you are running alum heads my understanding 
> is all things being equal and you are runnng a healthy cam with 
> lots of duration like Art is planning you should be able to GAIN a 
> point on compression or go from 10:1 to 11:1 but I could be 
> wrong....my 302B heads are 11:1 or 11.4:1.....OKAY DAN wotta say?
>
> Dawg
>
> Garth Rodericks wrote:
> Art,
>
> Your 377 stroker was running 10:1 compression with iron, closed 
> chamber heads, and you
> believe detonation killed it. Was the aforementioned CR before or 
> after the additional .020
> was milled off the heads?
>
> You want...
> - 408 stroker Cleveland built with CHI 3V aluminum heads
> - Max HP
> - Durability - I don't want to blow up any more engines due to detonation.
> - Plenty of compression ratio, 11 or 11.5:1
> - MSD knock sensor this time around
>
> My 2-cents, and that's about all it's worth...
> You're throwing your money away building a high compression engine. 
> This engine will fail in
> short order the way you want to drive it. Also, aluminum heads 
> usually increase the
> liklihood of detonation. So, forget high compression. The knock 
> sensor and in-car timing
> adjustments are merely band aids for the high CR and pump gas. And 
> you WILL NOT get
> max HP when you dial it back.
>
> Build a high HP low compression engine that will be durable and 
> reliable on pump gas. Bob
> Benson's Pantera has a 411 Windsor Dart block, Brodix heads, Scat 
> crank, steel rods, etc.
> and makes 550-600 HP with a CR less than 10:1 (I think it was 9.8:1, 
> but I don't recall for
> sure - Bob?)
>
> The point is you can make BIG power with a durable low compression 
> engine and pump gas.
>
> Here's a 9.2:1 CR 2V Cleveland that makes 520 HP on unleaded pump gas:
> http://www.kostecki.com.au/articles/art_of_power.html
>
> I think this engine will be much better suited to the way you want 
> to drive your car and will
> far outlast your proposed build.
>
> Keep us posted!
> Garth
>
>
>
>
> ---------------------------------
> Tonight's top picks. What will you watch tonight? Preview the 
> hottest shows on Yahoo! TV.
> _______________________________________________
>
> Detomaso Forum Managed by POCA
>
> Archive Search Engine Now Available at http://www.realbig.com/detomaso/
>
> DeTomaso mailing list
> DeTomaso at list.realbig.com
> http://list.realbig.com/mailman/listinfo/detomaso
>
>
>
> Mad Dawg Antenucci
> Team Pantera Racing
> The 1st & still the only vintage race team in open road racing
> www.teampanteraracing.com
> _______________________________________________
>
> Detomaso Forum Managed by POCA
>
> Archive Search Engine Now Available at http://www.realbig.com/detomaso/
>
> DeTomaso mailing list
> DeTomaso at list.realbig.com
> http://list.realbig.com/mailman/listinfo/detomaso
>



_______________________________________________

Detomaso Forum Managed by POCA

Archive Search Engine Now Available at http://www.realbig.com/detomaso/

DeTomaso mailing list
DeTomaso at list.realbig.com
http://list.realbig.com/mailman/listinfo/detomaso




More information about the DeTomaso mailing list