4AGE cams......choices, dyno results and discussions!!!

[Slimer86]

Small ports have a smaller internal area with comparison to the big port head.
Obvious yeah, I know, but as the area of flow increases, the velocity of the fluid in the area (port in this case) decreases, but as a side note, pressure in the port is increased.

Small port heads have a higher velocity of fluid flow in comparison to the big port head.

[Frak]

Small ports have a smaller internal area with comparison to the big port head.
Obvious yeah, I know, but as the area of flow increases, the velocity of the fluid in the area (port in this case) decreases, but as a side note, pressure in the port is increased.

Small port heads have a higher velocity of fluid flow in comparison to the big port head.

If someone can supply a nice clean bigport and small port head, I'll flow bench em.

[Classic_King]

i do but in briz

[sun_moon]

by the way

http://www.toymods.net/forums/showthread.php?t=3594

[trueno85]

how come you would only use the smallport head? i thought the rods are good enough to hold high rpm as long as you change the pins?

Sorry, didn't dial in after, once they were optimised I guess it doesn't matter other than for reference, but we ran out of time. If I had them(I guess I can find out) I would post up, no secrets.

The engine had been rebuilt so was fairly fresh.

sounds good mate, if you do find out what the settings were let me know as i would be very interested to know

[Classic_King]

If Bill Sherwood is anything to go by then if using 304 or more cams a big port might be a better option. Obviously this is a pretty crazy engine though.

180hp - 190hp
Definitely 304° cams, and you'll have to start paying attention to tuning the inlet manifold length, if you haven't done so already. This is also getting to the limit of what a lightly ported small port head can manage.

190hp - 200hp
Getting towards the upper limit of 304° cams, and you'll also need to have the compression up to a good 11:1. 200hp is about the limit for a small port head, no matter what the porting, so from here on the big port is the way to go. Another area that has pretty much reached its limit is the stock valves - Past 200hp you'll be needing the big valve kit. More on that next paragraph.
The standard exhaust manifold has also reached its limit, so 200hp is about as far as you can go with an engine that still retains a large amount of standard parts. It will need to be revved to around 9,000rpm to get 200hp, though if built properly the engine will still be able to be driven on the road.

I’m guessing those hp figures are it the flywheel.

[sun_moon]

well a smallport has the best port velocity and also compression stock compare to a bigport also stock.

modify them both and still the smallport should have an advantage.

for a streetable engine i would always use a smallport.

my mr2 is a bigport and my trueno is a smallport and the 2 engines feel pretty different i think in terms of streetability and other factors.

toyota wouldnt switch to an inferior design

[slide86]

If I were to do a 16V I would only use a small port head.

same opinion for a forced induction engine?

[land yacht]

for forced induction 20v

[Robo86]

hmm after this i now want ae111 quads + hks 264s... like the sound of 90 wheel kw