extreme engine tech na 4ag

[ga_goosh]

I came across this site that lists all the weaknesses in the 4ag and ways to increase longevity in a high performance 4ag. check it out.

http://www.motoiq.com/magazine_articles ... a-4ag.aspx

[drift]

hmm, good read and nice find

[dr.occa]

Yes, the biggest problem with the 4AG is the flexing at higher and sustained rpms.

[joel26]

nice find on this article

[mooreofit]

im willing to bet all that crank deflecting is engine harmonics, its funny how boost changes this.micks old boss who builds and races rail cars says its not detonation that kills most of his motors its the vacuum created in the cylinder on the intake stroke coauses such an extreme torsional load on the rod.he told me stories of rod bearings wrist pin failures and ring lands ripped from the piston.as long as the motor is under boost it doesnt have this fight which free's up power and lowers damaging engine harmonics.Its why i think boosted 4ag dont brake cranks at 250 whp.

this article still makes me want to gurdle my mains with another design that would tie into the webbing also and bloc fill. i dont feel the block guard is really nessisary in 4ag under boost till 4-450 whp.and this is not for harmonic reasons.its to bolster the cylinder wall as i hear they split around 500hp.

[dr.occa]

I'm in agreement with Alan; it's harmonics/vibration resonance. When you've got components spinning at sustained, high revolutions, it's doing the waltz on the edge of a cliff for more than 5 minutes. Boost introduces the power through compression on fewer strokes. Timing is given more room to sink the ball in the basket if you know what I mean. It's power in a relaxed state rather than in a frantic state.

Rotaries on the other hand...

[mooreofit]

yep rotaries dont have this issue.the loads are still there just applied in circular motion and dont have a reciprocating force to add to harmonic distortions. allthough adding boost will put allmost all load\force pushing down on the rod and not the crank having to pull down the rod cap during intake stroke.only force applied on crank at all times are down.and the combustion\ exhaust stroke does not have to fight the resistance of the vacuum on the intake stroke of another cylinder. greatly reducing engine harmonics under boost.

[dr.occa]

As for high rpm rotaries, it's easy to get them setup for 8K rpm and above. The rotating assembly just needs to be sent in to like Racing Beat, Pineapple Racing or Mazdatrix and dynamically balanced. It's not expensive really. Under $300 and you've got a steady, high revving wankel.

[joel26]

^^^^^ good to know........

[mooreofit]

he said wankel...