1JZ performance head build. Advice/help?

[EldarO]

Just all the stuff up top I guess. Just some tips on rebuilding and advice on the performance recipe. Things like the valve ratio are what I'm really keen on.

Also can anyone confirm that over 9mm lift makes the 1JZ an interferrence engine? soarercentral second hand info. Stupid questions probably but what does this mean for me? I know I will have to be careful when I reassemble, but anything else?

Any thoughts on what my new rev limit would be with the proposed set up?

Cheers!

Triptek had a bent valve in his 1J from the timing belt being setup wrong and the piston hitting it.

i thought it was non-interference too.

Elmo.

[ReQuieM]

Sorry for the late reply, easter and then gettign back to work after a nice break!

Makes 100% sense. So much so that I feel like a dick for asking instead of working out myself!

Hmm... seams the duration at .050" Isn't listed unless I'm interperating them wrong. Heres the 'tech' specs:

Spec (unit: mm)
Duration Lift VC
IN 64 (256) 9.3 0.20
EX 0.30
IN 66 (264) 9.3 0.20
EX 0.30

VC = Valve clearance.

Hope that helps..


Emo, They're non-interference, Triptek's turned out to be something else IIRC. 'Cos I was looking at buying it off him! I will be treating it as if it is interference tho, best to play the safe card!

[ReQuieM]

Fuck I spaced that table out. I hope you can still decipther it. Other wise hit up this url for the nice pretty table:

http://www.junauto.co.jp/products/cy...ft-1jz.html?en

[jeffro ra28]

Alright seeming as they do not state in .050".

Ill give you an example of my own. My 2tg is running around 260 cams which turns out to be 233 @ .050". These come on at about 5000 rpm but start to run out at around 7000-7500. Idle is fine, if tuned correctly. I can idle down the street at 1000rpm without any neck breaking jerks at all. Overhead cams dont seem to give the jerky affect as do pushrod v8's...etc

I used to own 298 degree cams for my 18rg, which i never got to use, however these are considered very large cams.

Tho engines at work we are running close to 290 at .050" which is big, and we have 1100 foot pounds of torque at 3500rpm and still 1100 foot pounds at like 7500rpm and a shit load more in between those two RPM's. This however is a different ball park all together. Just an example of what can be done.

If it where me id be going the 272 cams. With EFI, you can tune it to make up for the lost power down low anyhow.

Just a few cents worth mate. Hope it helps you out.
Please more questions!

[chris davey]

Great thread and good info. I am sure this info. will come in handy for others in the future

[ReQuieM]

Fk it I didn't get an email alert that someone had replied. Crakin it.

Wouldn't I be over caming the engine if I drop a pair of '272's' in with the stock turbos? I will be upgrading them down the road but I want to push the stockies hard before I do. So I guess I was looking for a cam that wont hurt the performance on the stockies but will still have head room to help the new twins when I build them up.

Jeffro what do you think about the port matching the exhuast? The US 7m boys don't port match the exhaust manifold side because the claim they loose bottom end. Idealy I'm aiming to build the engine up to make power off boost, obviously with out increasing compression. So I want a fat low end as well. Any thoughts hints?

OH and do you think I should be fine to de-bur and remover a small amount from the ports my self or could I seriously fk some thing up? It was mainly going from the main run of the ports. I wasn't going to touch the resses directly behind the valve as I've heard that is an extremely important area for the flow characteristics of the ports.

I thought that when I get teh head back from the port job I would polish up the exhaust ports, I don't think I can fk that up! I fine to use normaly polishing waxes yeah?

Cheers again, you been a fkn massive help. It's a pitty your in NSW, I'd buy you a bunch of beers and probably get you to the work on my head. Sounds like you know more then most the 'Professionsals' I've talked to!

[jeffro ra28]

Looking at it that way, yeah probably might be overdoing the cam thing with 272's but they still arent very big! I checked the otherday and the "advertised" duration of some of the cams we use in our race engines is 350 degrees...lol.

There isnt much to go wrong when cleaning up ports yourself, pay particular attention to the short turn of the port on both intake and exhaust. I am a big beliver in feel, a blind man would probly do a better port job i think because feel is everything, not look. Feel the ports and like i say, particular attention to the short turn radius.
Port matching brings things to a slightly more complicated level as if its done properly generally makes the ports much larger, and if blended properly will massively increase port volume. But huge improvements are still acheivable without going to all out.

Be very carefull around the valve seat area of the ports, do not nick the valve seat with the grinding bur, also stay away from head gasket surafce, obviously.

Port matching exhaust if done correctly is good. It is helpful not to leave a step from head to pipe on the bottom side of the port but if the pipe is larger then the exhaust port on the topside this is good as it helps stop reversion. Only on the top side however. It means that if any reversion where going to take place, it comes back up the pipe on the top side of the port and bang hits the step on the cylinder head. whamo, there goes your reversion. *Cough* reversion shouldnt be to much problem with forced induction.

As far as cleaning up intake ports, a nice sand/beed blasted finished is desired, as mirror like port finishes prevent atomisation of the air fule mixture. A fine sanded finished will help atomisation. On exhaust port however, mirror finishes are good as it also helps stop carbon build up! However i wouldnt be to concerned about that.

A good finish on intake can be gained with 60 grit emry paper "Pferd" brand is shit house, try and by "Carborundum" or somthing like that when you go to buy the stuff. Simply get a shaft for the grinder, cut a hacksaw slit in it and slide a 10cm length into the slot and roll it up. There you go, the perfect port polisher.


Professionals, when it comes to cylinder head ports, there is no such thing, i dont think anyone has come up with the PERFECT port design yet. However the motorbike industry is getting mighty close!

[ReQuieM]

Sorry my laptop is gettign fixed at the moment so I ponly have net access from work. SO kinda sporatic!

Thanx again for the info. I might start cleaning and deburring the head this weekend. I'd just had a bt of inspiration so now I want the head done so I can see some results! I guess all I have left to do is find a reputable porter/engine builder in melb to finish of the port job.

Cheers again!

[ReQuieM]

Sorry I can't give you any more rep!

[petespipes]

I would like to suggest that you could recognise the biggest name,most succesful power gainer or two or three in the specific area that you want and ask them\copy them\research them.
1jz racing could be worth contacting [he uses this site] and other guys that actually race 1js will probably have the engine specific info you need.

Best wishes.

[beatle]

so how did this all go?

[ReQuieM]

Not yet. Was waiting to sel my rims to fund the cams. But now I have other things to buy... soon, soon.... The head is ready and waiting for funds.