20v building na

[pornstr20v]

hey guys building a 20v monster (head is all done)
i was wondering wat parts i can use
Pistons?
rods? how would stock ones go
hows would the crank go?
any other parts i would need

im going for a na build looking for big power with big comp

what fuel setup as well

[oldcorollas]

what rpm, what cams? (duration, lift) etc

how much power, and how long do you want it to last?

[fixeruperer]

and what fuel do you want to run.

[GEMTA22]

What ecu you got or planning to use ?
What sort of power you after ?
Is it setup for rwd ?

[-GT-]

How have you got a complete head built for this monster NA and have no idea about the bottom end?? Surely this engine has all been designed together? ie cam duration, lift and timing with respect to piston clearance, compression, combustion chamber cc's, head flow and gasket thickness? Cam's rev range and peak power rpm target with engine rev limit and mean and peak piston speed and acceleration?

What about gearing and final drive ratio to suit this rev range? Or will you worry about that later?

To start with, we'll need at least all the specs you can provide on this head to even ballpark answers to your questions.

[Billzilla]

Wrong head, you should have used a 16v big port sorry mate.

[Brendan]

Bill is right.

Bottom end i'll go off what ive been told from the toda guy who seemed good imo.

They do pistons upto 11.8:1, use a metal headgasket, or u could O ring with a custom copper one, rods may need to be shot peened but the rods are ok, rod bolts, mains and head studs should all be replaced, crank may need some serious work pending how high rpm u plan on using.

We really need more info to help you.

[Chrisso]

I think you should read Ed's thread here: http://www.toymods.net/forums/showth...t=build+engine

[The Real Roadrunner]

Wrong head, you should have used a 16v big port sorry mate.

Why? ive already seen 200hp atw out of an N/A 20v.

Whats specifically stands out to say its wrong?

If the bigport is the "gun" head to use why did toyota stop producing it and go for other more efficient head designs?

That's like saying a Gen1 3sge head is better than a gen5 head without giving good reasons let alone results.

If your basing your theory off the fact that FA ran the bigport head then you may want to look into the reasons why they used it and no other head.

I don't know the OP but would like to find out the reasons behind your logic.

Cheers
Linden

[oldcorollas]

i think it is due to the valve area, and port size at the high rpms (10-11K) needed to get that sort of power from a 1.6L....

small port and 20V are better in midrange.. but do they choke earlier than the bigport?
and then you have cam lift, bucket size, etc

[The Real Roadrunner]

There are heaps of different things that affect it like ramp angles, duration, total lift, shrouding etc. as far as the ports being too small goes, doubt it.

check they airflow path on a 16v head versus that of a 20v, its like chalk and cheese. not to mention the port area on the 16v bigport is waaayyyyy too big.

Why would you want to rev an engine that hard? ive never seen a reason to go past 10k on anything bigger than 1.3L. how big is the usable rev band once you start building to suit 10K+ revs? whats the average power like?

Sure it might make bulk HP but it wont be fast unless its kept in its powerband (fine if you have a hewland quickchange box) and the moment you drop it off "song" it will be a pig.

Im yet to see anyone in Aust actually build a big HP 16v but feel free to post graphs of those over 150hp, many ppl talk about it but im yet to see one running.

Cheers
Linden

[Billzilla]

Why? ive already seen 200hp atw out of an N/A 20v.

Whats specifically stands out to say its wrong?

Simply because you can run much bigger cams in a 16v head than a 20v. You need big cams to make power at high revs.
I can expand on that, but the cam consideration alone is enough to make anyone building a big HP engine choose a 16v head over a 20v.

Im yet to see anyone in Aust actually build a big HP 16v but feel free to post graphs of those over 150hp, many ppl talk about it but im yet to see one running.

Well you have now - The last 16v I built was just a good street engine and it was about 185hp. Chris O'Shannessy's 16v makes more power than any 20v anywhere that I have ever heard of as well.

[GEMTA22]

Is that 185 rwhp you built mate ?
Care to share the specs bottom end and head specs ?

Cheers

[The Real Roadrunner]

Bill,
What are the max sizes for either? ive never measured them up personally but i cant see much more than an extra 1.5mm or so of lift being involved. does it also coincide with when they bind springs etc, is there more meat in the head to mill out for stronger springs to fit?

even the FA engines didn't run the biggest cams they where allowed to so im yet to see a good reason why the 20v head is worse when you probly couldn't even "use" the bigest cam you could fit.

Ive seen a couple of 20v's go past 10K revs, any real need to go further (other than wearing the engine out)?

[Billzilla]

The limit is the tiny 23mm bucket the 20v's use. The 16v's run 28mm buckets so you can use larger duration but perhaps more importantly lift cams. You're struggling to get much more than about 0.380" lift into a 20v and I know you can get a 0.440" cam into a 16v.

(And this is one reason why I'm using the 7AFE head, with its 31mm buckets)