selecting an intake manifold

[grumpyvette]

info worth reading thru!

viewtopic.php?f=52&t=322

http://victorylibrary.com/mopar/intake-tech-c.htm

viewtopic.php?f=55&t=624

WATCH THIS
http://www.youtube.com/watch?v=N_ART4SBmdg

http://www.youtube.com/watch?v=lqqtK0lP ... _embedded#


OK for the guys that don,t like reading ILL make this short and to the point,
when selecting an intake manifold the cam timing and compression ratio of the engine, and the header scavaging tunned rpm range should match the intended rpm band., IF it does, it simplifies intake selection.
IN about 80% plus of the cases Ive seen if the rest of the combos set up too match the cam timing and head flow,rates, youll rarely see a single plane intake work well with a cam that has LESS THAN about 235 degs duration at .050 lift and youll rarely see a dual plane work as well as a properly set up single plane intake with a cam with over about 250 duration at .050 lift or with a heavy nitrous shot.
It that 235-250 at .050 duration range that tends to be finicky on what works best.
naturally displacement , compression and gearing effect results, but if you read thru the three links above and do a few honest tests I think youll see as I have that those factors hold true much of the time!

 

[grumpyvette]

youll die of old age useing a dremel to port with....and keeping the burr wet with WD 40 helps a bunch

http://www.harborfreight.com/cpi/ctaf/D ... mber=93621

http://www.burrs4less.com/catalog/E_Ser ... g-8-1.html

http://www.diyporting.com/Shrouding.html

viewtopic.php?f=44&t=392&p=5415#p5415

http://boosted.envy.nu/articles/porting1.htm

http://www.gmtips.com/3rd-degree/dox/ti ... t/port.htm

http://hotrod.automotive.com/71320/hrdp ... index.html

http://www.sa-motorsports.com/diyport.aspx

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

http://www.eecis.udel.edu/~davis/z28/buildup/plenum/

http://www.froadin.com/eng_mod_int.html

http://www.ws6transam.org/ported.html

http://www.gofastnews.com/board/technic ... l#post5343

info worth reading


http://www.superchevy.com/technical/eng ... _test.html


look this is not a guessing game (selecting the correct port size)you select and verify the correct port size and cross sectional area,using know calculations, valve diam. and flow rate for the application, verify clearances in the valve train,and that the cam and valve train are compatible for the intended rpm band and stress levels,
you match the cams intended rpm and power band to the displacement and compression ratio,make sure the valve curtain are exceeds the port cross section slightly , select the cam lift and duration to maximize the port flow,potential, select headers designed to operate in the same power band, select a drive train that keeps the engine in that power band most of the time.

http://www.rbracing-rsr.com/runnertorquecalc.html

viewtopic.php?f=52&t=322

viewtopic.php?f=56&t=1730


just a question,for you gentlemen, who think they need a larger carb, to go faster, now you may need that carb, but having some basic, info to use helps,I see these discussions on selecting carb sizes frequently, but IM amazed at how rare it is for someone to actually hook up a quality vacuum gauge, or data logger, and an air/fuel ratio gauge to the plenum and header collectors have some buddy log the true air pressure readings in the plenum and f/a ratio as the car travels thru the track. now thats always been my approach,naturally you need to have a known ignition advance and a steady fuel pressure etc, and reading plugs and use of an INFRARED TEMP GUN on the headers just after a run looking for some consistency in temps doesn,t hurt with that info added
generally Ive found that if your WOT vacuum drops in the plenum , as your running thru the lights to between 1" and 0.5"going to a larger carbs, rarely going to give any noticeable gains, and generally keeping the f/a ratio in the engine at the top end of the track to in the 12.5-13:1 range will produce the best times, but Ive only had 40 years doing this stuff and IM still learning and wide open to suggestions

thoughts guys?