Toymods Car Club Inc: Tech & Conversions => Staggered cam sizes

Toymods Car Club
www.toymods.org.au

F.A.Q.

Home

Members

Toymods » Tech & Conversions » Staggered cam sizes - 4AGZE Show: Today's Posts :: Show Polls Email to friend

Author

Topic

oldcorollas
Forums Junkie

Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003

Re: Staggered cam sizes - 4AGZE	Thu, 08 September 2005 06:03

well... think about it logically.. by changing cams you change open/close points of valve, and also overlap. with SC you have higher pressure in intake than exhaust, so you shouldn't need to worry about reverse flow as much as the turbo kiddies. you do need to worry about overlap more than the turbo kiddies tho as you will blow mixture out when overlap is occurring (compared to having high exhaust manifold pressure keeping the mixture in) so overlap is bad. but overlap is needed at higher rpm (i think) so that there is enough time for mixture to get into cylinder, and so exhaust scavenging does occur. since 4A flows reasobaly well as it is, maybe you could just get away with high lift cams as opposed to more overlap. as for duration.... closing of exhaust and opening of intake controls overlap, so we are just thinking about opening of exhaust and closing of intake. you could open exhaust earlier, since end of power stroke may not add so much anyway, but i'm unsure of how early is too early. you could leave intake open longer, since you have higher intake pressure than NA, and you will continue to fill cylinder past the point that would happen with NA... so as long as you set the lobe angles to control overlap, have high lift cams with aggressive ramp rates, then you can probably experiment with duration and not lose out too much, since you can adjust them to affect the exhaust opening and intake closing, and leave the other points alone-ish.. what are stock duration cams?? in 272 NA 4AG, cam comes on at what? 4000rpm?? with these in SC, unless you adjust overlap, then you will still have not so good bottom end as overlap is too big to build pressure??? as for staggered, it depends on the relative ability of the head to flow. ie for K motors, exhaust is worse, so you have a longer exhaust duration. i think the only way to really tell (unless someone has results they are willing to share) would be to get sayy stock, 256, 264 and maybe 272, IN and EX, and dyno the buggers.... which do you thinki smore restrictive? the intake or exhaust? [Report message to a moderator]

[Message index]

-=] Back to Top [=-

Current Time: Sat Feb 8 12:44:24 UTC 2025

Total time taken to generate the page: 0.0068750381469727 seconds

.:: Contact :: Home ::.