20v and aftermarket cams...

[Just1n_mc]

So I'm In the process of building another Silvertop 20v and was hoping I could get some real world advice about cams.

I'd like to retain the VVT and factory rev limit but use larger cams for a bit more power up top. I've found numerous manufacturers who make them but none of them back them up with dyno sheets.

Who has fitted aftermarket cams to their 20V and what power have they gotten from them?

Any advise would be greatly appreciated.

[Celica RA45]

try kelfords in nz they might have a profile that will still retain the vvt

[Just1n_mc]

The problem is they don't back up there cams with any dyno sheets. Looking at there website you can retain the VVT up till the 194-C profile.

The only cams I can find with dyno sheets are the Tomei Poncams 264 Inlet and 256 Exhaust.

[xero]

why do you need a dyno sheet to back up cams? all its going to show is that on that particular engine they made XXX power. each engine is different and each engine reacts differently. hell even adding adjustable cam gears to STOCK cams will allow you to change the power around. just by adding X cams to Y engine will not result in Z power. then you have to take into account drivetrain layout, AWD will have more drive train loss, RWD loss will not be as big as AWD, and FWD drivetrain loss will be the least of both.
a dyno is just a tool for measurement its not the be-all and end-all for a engine.

as Glenn has said kelfords would be your best bet for the profile to retain VVT. otherwise talk to your engine builder (or find one to talk to), talk to your tuner and do some reading on other cars with the same cams you would like and see how they respond.

[shrike]

From Memory 272 is and 11mm lift is the biggest you can go with vvt but i could be wrong

The question is do you want more top end or more low down Torque

Whats the application

[dnegative]

If you go bigger you will probably need to rev it more...

[Just1n_mc]

It's for my AE82 Racecar so I'm wanting a bit more up top.

I was thinking along the lines of Tomei Poncams which are 264/254 or a set of kelford 194-b's

[Just1n_mc]

After talking to some people now I completely confused.

Best I can tell getting air into the engine isn't an issue having quad throttle bodies and 3 intake valves. Getting the exhaust out seems to be the restriction. Is there any merit in running a longer duration exhaust cam than inlet? I see they use staggered cams in the 16v's (normally larger inlet) with great success but apart from the tomei poncams you don't here about it being done much in the 20v let alone running a larger exhaust cam.

[Celica RA45]

just remember that the 3 inlet valves are still bigger than the exhaust and from memory TRD used a 304 inlet and a 312 on the exhaust
this was for the black top 20v motor thou

[Just1n_mc]

That was my logic as well. Having the larger exhaust cam to help it breathe and staggering them helps give a wider powerband.

I was thinking along the lines of a 265 intake and 276 exhaust but just wasn't sure if my theory was correct.

[dumbass]

what ecu u going to run
air flow meters don't like big cams

[Just1n_mc]

I'm running an emanage blue currently.

[Just1n_mc]

So I have bought a new head to go onto the bottom end I'm building that has been professionally built (ported, flowed, valve grind and re-seat, toda valve springs Toda adjustable cam gears.) But it has 282 duration cams with 8.7mm lift on both the inlet and exhaust.

I'm still toying with the idea of going with a lower duration higher lift intake cam like a Toda 272 9.2mm as I think it could help make better power.

Any thoughts??

I'm also now running a Haltech Sprint 500 ECU and running a coil over plug setup.

[xero]

leave the 280s, lift bigger than what they have will have the intake cam lobes touching the spark plug tubes and will need to be clearanced.
what is going to be the static compression ratio you will have?

[Just1n_mc]

Should be The best part of 11:1 with a TRD head gasket.

I thought you could run a lot more lift than that before you had clearance issues with the spark plug tubes?? The Tomei Poncams are 9mm lift and they are just drop in.