TVIS+cams+Itb

[Rice86]

car - AE86
engine - 16v 4age bigport

im going with the T3+20v itb setup on my 16v bigport

have toda 264 7.9 and 272 7.9 cams and toda adj cam gears to suit

Questions.

Is it possible to keep TVIS with T3+20v itb setup?
is it worth keeping if possible?
are these cams direct bolt in without any other modifications needed?


EDIT, added question

What is best for this setup i am going with, Silver top ITB or Blacktop ITB?

[sundee]

Ditch the TVIS
Cams, 264 are a bolt in , 272 are not considered a bolt in, I would do valve springs if it were my engine

[timbo]

How are you going to run them, i.e. 272in 264out? 7.9 isn't much lift to do springs.

[meadan]

My cams have 7.9mm lift and Im running stock valve springs. Thats in a smallport though.

Im pretty sure the stock bigport cams have 7.9mm lift anyway? I think I read somewhere anything over 8mm lift is where you might want to worry about spitting out shims, Ill look for the link again.

[sundee]

So if you had 8.1mm lift you would do valve springs but not for 7.9mm
For the sake of a few hundred bux, you have 100% reliability .
In the end it's your engine, but for the cost of valve springs it's really a no brainer

[timbo]

Well I don't agree with that, it is like replacing something that doesn't need to and purely for the sake of it. Yeah, 8.1mm may need new springs and buckets, but if anyone was going for some serious cams I'm sure they would have AT LEAST 9mm of lift and a much bigger duration. You do what you need to, to make it work. I didn't replace my oil and water pumps during a rebuild because I pulled them apart and they were fine. I just think something like that is doing it for the sake of it, just because it is easy to do when the cams go in.

[sundee]

We seem to think very differently, I don't like to do things twice.

[meadan]

According to billzilla

Bigport has 7.56mm lift
Smallport has 7.1mm lift

[Rice86]

to be honest not to sure, but whatever way that will work the best to get performance with this setup. so someone that knows their shit can advise or the tuner should be able to advise what would be best anyways

Cheers Adan! can i ask for a favor for help with the installation of the cams and ITB when the time comes? lol

i totally agree but in this case what works shall be left alone..and if it seems like springs are needed then springs will be bought no doubt.

ALSO i know you told me to ditch the TVIS, care to elaborate on reasons or anyone else?

i just don't want this to feel like a dog from 1000-4000rpm if you know what i mean. it still is going to be a very standardish bigport motor

[sundee]

Quote from billzilla's modified 4ag page:

Note that with cams larger than about the 260° mark you will actually benefit from removing the TVIS, if fitted. The TVIS, when used with cams smaller than about that duration, will give you more low end ( < 4,400rpm) power, but this effect disappears with the bigger cams.


Smart man, good enough for me.
And makes sence to, with the larger duration you have shifted the power band above the rpm range that the Tvis works in.
And if your going to make any decent power from an NA it needs large duration cams, and it's trade off for the extra top end is a loss of low/mid range torque.
There is actually no way around it.. Except force feed it.