2018 FS showdown posted.

[Rob Wright]

Off the top of my head that looks reasonable Todd, and it clearly shows that with current legal lift specs the Ford has more combined into/exh airflow potential than the GM and.the Mopar.

Throttle blade area is same/same on GM and Mopar and no surprise since they share the exact same 109mm round bore throttle body.

Ford has an oval-shaped throttle bore & I'd bet it has about 25% more area than the COPO & DP.

In 1997, the high volume production Ford 4v valvetrain was capable of running continuously at 8,000 RPM.....My bet is they got better over the past 20 years.

Not sure how the efficiency maps look for Whipple blowers.....when I asked I was told their data was on a laptop that was in a vehicle that was stolen & never recovered. Unless the 4.0L is horribly inefficient compared to the 2.9L, it has about 38% more capacity....makes sense since 4.0L with 25%-ish slower drive speed matches power output of 2.9L on same/same engine.

Just thoughts........

Originally Posted by JMan;549615[FONT=Georgia

Interesting exercise Rob.

If I calculated right.

Chevy with .641 lift = 4.349 sq.in Int / 3.185 Ex
Mopar with .591/.589 lift = 3.891 sq.in Int / 3.008 Ex
Ford 5.4 with .473 lift = 4.255 sq.in Int / 3.682 Ex

The 4 smaller valves of the Ford increases the curtain area at a lower lift vs. a 2 valve with greater lift.[/FONT]

[bsimms89]

http://nhraracer.com/content/general...362&zoneid=132

Seems they issued a correction stating that the Cobra Jets with the 4.0L Whipple aren't actually permitted.

[D.Johns]

Mute point as we all basically make very close to same power in class legal form with the exception of the TVS which is the underdog in the fight. It needs more weight off and/or more blower speed.

Originally Posted by Rob Wright

Off the top of my head that looks reasonable Todd, and it clearly shows that with current legal lift specs the Ford has more combined into/exh airflow potential than the GM and.the Mopar.

Throttle blade area is same/same on GM and Mopar and no surprise since they share the exact same 109mm round bore throttle body.

Ford has an oval-shaped throttle bore & I'd bet it has about 25% more area than the COPO & DP.

In 1997, the high volume production Ford 4v valvetrain was capable of running continuously at 8,000 RPM.....My bet is they got better over the past 20 years.

Not sure how the efficiency maps look for Whipple blowers.....when I asked I was told their data was on a laptop that was in a vehicle that was stolen & never recovered. Unless the 4.0L is horribly inefficient compared to the 2.9L, it has about 38% more capacity....makes sense since 4.0L with 25%-ish slower drive speed matches power output of 2.9L on same/same engine.

Just thoughts........

[Rob Wright]

Completely agree - they're all pretty close & no surprise since all of them are fed by the same compressor.

The OP has been pitching the disadvantages with CJ since the first day that something else ran quicker, so I think it's worth pointing out the advantages of CJ to balance perspective a bit.

Originally Posted by D.Johns

Mute point as we all basically make very close to same power in class legal form with the exception of the TVS which is the underdog in the fight. It needs more weight off and/or more blower speed.

[D.Johns]

Like you stated the 4v has an advantage of valve curtain area. That is an inherent advantage of multiple valve engines. It also has an advantage of valvetrain stability at lower lifts for higher RPM. It also has disadvantages as well even on the valve area as it is a small bore so the valves are shrouded a somewhat. There are inherent pro’s and con’s to every engine architecture and vehicles chassis/aero. The LS and MOPAR as advantages in some aspects and the Modular has some in others. Valve curtain area is not the “smoking gun”. The combinations as a whole are close in the real world(not identical that’s for sure) but any combo could win any round. Everyone will continue to advance their program to eliminate or work around the inherent short comings and capitalize on their strengths.

Everyone will fight to gain an advantage over the competition. The rule makers usually try to keep the parity.(unless corrupt....)