20v

[philip]

Hey I've heard that the 20v silver top is just as quick as the 4agze. Is this true? I was going for the ze conversion but the insurance is high so if it is as good I'll do that one intsead.
Any help would be great.:)

[rob_RA40]

standing start the GZE will munch it
100km/h roll on the 20V will have the legs

[Sxer]

Agreed.
Around town the gze should much a 20V. Around a track a 20V would be closer. The 123kW that toyota claim for the 20v is generally considered pretty optimistic and most seem to put out lower levels than this. the gze though can be made to hammer and is easier to convert to turbo should you decide to go ballistic with it.

check out
toymods (www.toymods.org.au) for more info on toyota engines

cheers big ears

[Rex_Kelway]

The 4AGZE has a nice whack of low/mid range stomp. The problem however is that it really cant breathe to well higher in the rev range, this is why they tend to get a bit flat beyond 5500rpm.

The 20V though breathes very well right through the range and has the ability to rev like a bitch, but has none of the midrange of its S/C'd brother.


I would say that the two engines should really not be compared, to decide which is a better choice. They both appeal to totally different types of drivers/situations. Unless of course you take the tough as nails 4AGZE, lose the supercharger and turbocharge it instead, then you can have revs and boost.

[skitz_supra]

bolt the 20v head to the GZE bottom end, perfect for a turbo.....

[Rex_Kelway]

Not necessarily, The 20V head was designed wholly to produce good air velocity using only atmospheric pressure and vacuum to fill the cylinder. The idea being to help the little 1600cc displacement build as much torque as possible.

When forced induction is on the cards the conventional atmospheric inlet efficiency theory suddenly goes out the window. It then becomes (basically) an excercise in stuffing as much air through the head and into the cylinder as possible.

This is why in my opinion the 16V Bigport head is better for forced induction.

[Billzilla]

Originally posted by Rex_Kelway
Not necessarily, The 20V head was designed wholly to produce good air velocity using only atmospheric pressure and vacuum to fill the cylinder. The idea being to help the little 1600cc displacement build as much torque as possible.

When forced induction is on the cards the conventional atmospheric inlet efficiency theory suddenly goes out the window. It then becomes (basically) an excercise in stuffing as much air through the head and into the cylinder as possible.

This is why in my opinion the 16V Bigport head is better for forced induction.

I have an alternate theory, Rex.
I think that the airflow goes down the ports at a not much higher speed, but rather at a higher pressure. If you look at the ports of successful turbo engines, they aren't much bigger than n/a ones in many cases.
I'm going to build a turbo 7AG and will be using the 20v head, as they have more valve area than the 16v does and I think that's a good thing to help the breathing under boost. They also have VVT which I reckon is a good thing for helping the turbo get up on boost earlier and make torque longer.

[Rex_Kelway]

Ohh you do, do you Bill :D ,

Thats a hell of a co-incidence too, Im also building a 7AGE as a hillclimb engine, except supercharged with a simple Sigma dizzy and fuel only ECU. Dirt Cheap grunt methinks (hopes)


Speaking N/A at the moment.

Rex thinks the airflow pressure has more to do with the complete intake design rather than just the ports. Ie: The plenum chamber is designed to help cylinder filling through reflective pulsing.

Forced,

Rex also believes that XXpsi pressure of static air in a small volume port is the same as XXpsi in a large volume port, however when these same ports are required to flow masses of air the larger port has the potential to flow much more.

So, :p :D

PS, Nice to see you on AussieClubmans too Bill, why can i not escape you :D:D:D. How much is the Fraser supposed to weigh all up?

[Billzilla]

The Leitch?
No idea, I'm not building one! :D
The Fraser, I'm hoping, will be down around the 530kg mark though it might be a little heavier.

Rex is right about the complete inlet system being cruicial.

[Rex_Kelway]

Jesus!! you must be quick, I edited that post (Leitch > Fraser) about 3 minutes after the original post.

I got confused between you and another bloke i know who's having a Leitch arrive soon.

Nonetheless, 530Kg is very light indeed!!!

[itsnotagsr]

on wakefield: 20v better vs 4agze (airflow meter version)
traffic light drag: 4agze

[Kouki]

Rex/Bill,

is the problem (with the 4agze) head design or would it have more to do with S/C efficiency?

Cheers

[Billzilla]

Err ... what problem?
The 16v head is not too bad, but yes, the supercharger is not very good. They are a Roots type blower and so create a lot of heat.

[John]

Especially with a big pulley....... ;)

20v - for the NA purist
GZE - for a daily driver

J