1jz vs 2jz heads

[Norbie]

I've heard a couple of times that the 1.5jz is a 'torque monster'

Compared to a 1JZ it would be. I can't think of any reason a 1.5JZ would have significantly more torque than a 2JZ though. Seriously, have a look at the overall design of a 1JZ head and compare it to a 2JZ head - there's fuck all difference. Which makes me wonder why so many people keep going on about this 1.5JZ bullshit.

/rant

[chris davey]

Ok so this is all heresay and speculation, But I've heard a couple of times that the 1.5jz is a 'torque monster' could the differnce be similar to the difference between the 2-4valve windsor heads? One for torque, one for hp? I realise that the number of valves makes more of a differnce then a small amount of flow, and also the design as well. But it is a real world similarity that i could draw on. Could also explain why the tuner that 1jz747 see's uses the 1jz head as a preffered basis. 1jz747: is the work shop that recommends the 1jz head specialise in drag racing? To me torque is goooood

Not hearsay, it was tested.

I think you are referring to the old Hardcore Racing guys.

How many 1500hp 1.5jz's have you seen?

For a street car, I think there is SFA difference between a 1.5jz and a 2jz.

[1JZ.747]

my tuner uses a 1j head on a 1j cuase thats what it came with and thats what i went to him with.


i was talking about a whole other workshop in another state and the resutls they had found.

i will be 1.5jz due to allready having bolt on for my head. i just want the extra capacity. if i started with a 2j i would have stuck with a 2j


its pretty simple

and norbie, get the sand out of your vagina

[kingmick]

thought you guys might find this an intresting read!

http://www.competitionplus.com/2006_...der_heads.html

ive been lucky in that i was bought up with both pushrod and modern OHC engines.
in most cases the heads from most factories are a compromise, it all goes down to casting and what they achive with straight out casting. the 4ag is a good example! the flow well out of the box but to really change them you have to grind out in some areas of the ports and add to other parts to really get them flowing aswell as they possible can.

i think alot of people around the world get led a little bit a stray with flow figures and think that if heads can flow 800hp there engine is going to make 800hp. lol i come across this a fair bit and takes awhile to explain to them that is its the whole engine that needs to meet the 800hp mark not just the flow of the heads!

atmo engines are crucial in the way the ports are designed so you have the right velocity,especially road driven ones that you want to have power over a larger rev range. no point in a road car opening the thottle to have a huge flat spot till 3000rpm so max flow at max lift can work against a car that isnt using WOT for over 70% of its time on the track.
hence the diffrence between a circuit racing engine and rally engine. both have been setup to give HP and TORQUE were it is usefull and works where it is needed in both forms of racing. Drag racing you want maxflow hence why fulltime and some part time drag cars{ there not nice on the street} use 1100cfm+ carbies etc. as its WOT the whole time and they need everything max up time. thats a really basic and prob bad explanation.

Boosted is the same, but shaping for velocities the same as an ATMO will restict the boost being pushed in,where the atmo uses them to draw in air. With boosted on the street it is better to have a bit of restriction so there is power down low off boost. on the track its the same as a drag motor, you dont want restictions but you have to compromise a bit to improve drivabilty. A car that has power delivery like an on/off switch is a handfull to be consistant in.

hahaha dont worry about what i have said!lol atleast the link is usefull!