2JZ head porting.

[Billzilla]

Ported by Kelford Cams
Intake valve size 1.26"
Exhaust valve size 1.07"

FWIW that's with 2mm oversize valves.

[BigMuz]

rusty, I understand what it means but I wasn't sure what you guys meant in the context of 2js. I assumed that anything with a reasonable amount of power would have enough valve lift that this was all irrelevant. I'm a pushrod guy FFS :D

[Reaper]

Hey Rusty,

OK, spoke to Dusty (MVPMotorsports) this morning about stuff.

Asked him about these flow results from PHR's $6K USD CNC'd head. He advises that industry standard in the US is 28" but he does not know for sure that these results of 300/200 were based on that spec.

If I ever talk to PHR direct I'll ask but there you go, probably was 28"?

reaper do you know how many inches of vac phr is using to quote 300/200 ... doesnt say on their site.

[Reaper]

OK, just an update on this project.

All the snazzy parts are coming in from the US now. There was a slight hold up on some bits so things are taking a few days longer.

Anyhoo, the gist of what's happening now is - 1mm OS Brian Crower dished valves going in on both sides.
TK has only done the 1 cylinder so far and will now alter that one for the larger valves, and then presumably back to the flow bench later to see if the magical 300/200 is gonna be cracked.

The engine came out today. A big thanks to SuperCrown (and Alex - is he on here Sean?) for helping me do the final bit of yanking the engine out cleanly w/o fugging shit up. Considering Sean got so rat arsed last night he had double vision I'm impressed! I would have told him to get fucked if he needed the hand - I kid, I kid mate.

Block and bits are going down to Tony's (TK) - deck and hone block, line bore/hone crank journals to put big end and main holes back into round seeing as ARP studs/bolts are going down under.

TK's also porting/ cleaning up block oil galleries, fixing the oil pump drain/clearance issue (FMS failure on Supra's issue), 'aero'ing the throttle plate, port matching/cleaning up the intake runners/exh. mani etc.

We'll re-assemble the donk down at Tony's to check bearing health etc. This is going to be wicked to have access to Tony's professional facilities let alone the man himself advising how this shit should be done - thanks for the generous offer Tony - I can see why you are always so busy mate, you bust a gut to make the customer happy!

Time frame for all of this is maybe 2 weeks to get the engine all done and back to my shed. Then probably another 1-2 weeks to get Humpty Dumpty back together again. Then a few days to get the donkey on the rollers for a re-tune.

Have also been doing some research on Kelford cams. TK has been quite impressed with their performance on Rex heads he has produced. I've even called up these Kiwi's about their cams to discuss the amount of lift their cams have in the 268/272 range.

Link is here to the 2J cams page >> http://www.camshaftshop.com/camshaft...yota-camshaft/

Recent advice on this thread has been that 2J's become interference at about 10mm lift? I even checked this advice out with Dusty from MVPMotorsports and he agreed - just over 10mm was his advice. People have surmised that this is why every man and his dog punches out cams at ~9.5 mm for clearance? Idea is that too much lift necessitates fly cut piston tops to provide the additional clearance needed, or even new pistons altogether.

So, I called the Kelford Kiwi's and spoke to their 2IC, and later I think the main man - Kevin? and this is what they had to say:-

1) Valve to valve interference is miles away from happening on turbo cars since they run such relatively low cam overlaps. This risk is far more likely on an NA car which for the same level of development may run an additional 30 degrees of duration (eg. 236 @ 50 thou vs. say 266 at same lift for NA was example numbers quoted). Therefore not gonna happen due to high lobe separation on snailed up cars.

2) Valve to piston interference is not lift related specifically, it is a function of duration. The reason for this is due to the std mechanical timing. On the intake side at full lift the piston might already be some 12 degrees past TDC ie. valve is 'chasing' the piston down the bore. Kevin quoted that at TDC the intake valve may only be some 80 thou lifted - if you do the 'maths' it's a way a way.

It is allegedly even less likely that the exhaust side will become subject to valve to piston interference since it is so far advanced it might only be 30 thou lifted @ TDC.

Hmmmm... illuminating.

Now, the interesting part comes here - a la Mythbuster methodology - what would cause valve to piston interference if it is not strict lift only? The concatenation of events is this (apparently) - big phat cams (this will mean big duration and lift), farking with mechanical timing via cam gears, and the real secret sauce is valve float.

What can also be helpful is higher static comp closing up the combustion chamber's as this closes up the static gap between the valve and piston.

Put these things altogether and you might find this type of interference ruining your day.

Are Kelford's to be believed? Even the mighty MVP Dusty has been contradicted by this advice!

What's the answer? Opinions?

When I can be arsed I'm gonna look up my engine manual to see what light it can shed.

One last thing - Kevin and crew said on a street car you can test this shit by doing the following >>

1) rotate engine to TDC
2) clock cam to the top of the cam's lobe ie. max lift
3) use some tool to depress the bucket o' shim even further AND measure this gap

This is the gap between the valve at full lift (for that particular cam) and the piston at the top of it's stroke.

Kev said that on a street car you should aim to have this clearance be at least 2mm on both sides but that more than likely you'll find it is something like 4-5mm gap.

Soooo... if this is true where is all this 'interference' stuff coming from? If there is 1/2 a cm clear at max lift and piston TDC then running 11mm cams on oem pistons shouldn't be bad karma?

I've not spoken to these guys before, don't know about their rep., therefore don't know whether to trust them. Is this test sufficient to verify that the 9.9 mm lift on this 268/272 combo won't even be close to 'inter' contrary to (seemingly) many opinions?

Last bit of info was this - this combo is alleged to drop spool by about 200+rpm over stock Supra JDM cams. I thought it would be much more.

Kevin also advised that for my setup (800 crank) this is as far as he would go cam wise. He understands that the racey head will be great and make well good use of the cams ie. they will be in synch performance wise - the constraint cam wise is based more on the fact that the snail is probably not big enough to warrant 280's etc. The explanation is that the snail will run out of puff relative to the cams ability to flow air at about this level so 280's are unnecessary ie. overkill for snail max cfm.

OK, I'm rooted, lots of typing makes baby Jesus cry.

Hey, while I'm at it - does anyone have any suggestions for 2J things I should take care of/ look out for when putting this bad boy back in? ie. weaknesses to address, tips/tricks to avoid shit getting fucked up - please share.

Ta, cya,
call ya tomorrow TK - cheers mate,

GEE

[oldcorollas]

if you want to get technical about it, do sonething like they suggested.

fit a very light spring to 1 intake and 1 exhaust valve.
(and with head off) push 1 valve down to say, 15mm lift, and measure how much the valve protudes from the head. then do with other valve.

also, while head is off, open both valves until their edges just touch (ie, find the minimum lift required to be in a position to hit other valve).
this will basically give you the lift at the valve mid overlap point at which things feck up... (ie, if at anytime during overlap, both cams exceed this, your fecked.

next, knowing the valve protrusion (minus the head gasket thickness), rotate pistons and find what crank angle gives that space in the cylinder.

rotate back a bit, and then fit head with old gasket and torque up (close enough), and then...rotate engine 5 or 10 deg and push valve in till it hits... measure the lift needed.
do that every 5 deg or whatever and graph it. make sure to make a note of lift at TDC lift required as from that you can calculate what happens with different thickness HG's/head skims whatever.

so.. what you want to end up with is a graph of crank degrees vs lift required to cause contact.
armed with that, you can evaluate any cam with any duration, and any advance or retard, simply by plotting the valve lift vs crank degrees onto the same diagram....

there are easier ways to do it, but thats an easy to understand method that removes any doubts...

(or send me details of the piston to deck clearance vs crank degrees, and the lift required to cause valve to hit when head is placed on flat plate, and the valve angle, and i will graph it up for you)

(edit: if anyone has a 2J in bits in sydney, i'll offer to come measure it next month and put the rumours to rest...)

[BigMuz]

Forget the rumours/ internet/ salesman.

It doesn't matter

Just check that you have clearance at TDC and every 5 or ten degrees after that with the cam as advanced as you are likely to run it. (inlet side) and the same on the exhaust side (but retarded as far as you are likely to retard it)


I fail to see the big worry one way or the other- do they break belts all the time?

Then keep an eye on the belt and change it if you are suss.

[BigMuz]

Oh yeah and as sure i am of the success of this project, it seems to have snuck a fair way away from the original goal, which was to tweak the head on a big single equipped 2j and see the difference.

Now it is head, oversize valves, cams, engine rebuild, tweaking the oiling system, porting the manifold, improving the throttle body.

I know it is the logical time to do it, but are you not concerned about this stuff muddying the waters somewhat?

[TK]

Oh yeah and as sure i am of the success of this project, it seems to have snuck a fair way away from the original goal, which was to tweak the head on a big single equipped 2j and see the difference.

Now it is head, oversize valves, cams, engine rebuild, tweaking the oiling system, porting the manifold, improving the throttle body.

I know it is the logical time to do it, but are you not concerned about this stuff muddying the waters somewhat?

Not really muz, the bottom end freshen & oiling system mods is only being done because it seems silly not to while the engine is in bits, it won't affect power because compression was good before hand - it's more a reliability & peace of mind thing.
After porting the head with stock valves it became fairly obvious that the valve size is the biggest restriction - if a customer is prepared to spend $2.5k on a ported head + another $1k on gaskets, head bolts etc to refit it then the cost of a set of valves is fairly minor - you'd be mad to spend all that money & stick with stock valves. My original idea for using stock valves was based on other multi-valve heads I have done which did not show a huge difference in flow - their valve sizes were a lot better to start with - but that's not the case with a 2J, the stock valves are just too small.
Manifold porting will be restricted to match porting & knocking off the lumps - I do this for virtually every ported head, it's just part of the job, ported throttle body is, again, a minor job - 1 - 1 1/2 hours max, just doing it because it's there & is a sensible thing to do.
Cams will go in later, it'll be run with the stockers for a while.

At the end of this I'll work out a price on a package deal - ported head with larger valves, match ported intake & ex manifolds, ported throttle body + the option of cams to suit.

TK

[Nero]

Given the effort going into this I am surprised that anyone would consider the advice of a supplier such that you would not bother to do a static check on the components as assembeled. My last engine was together and apart 4 times before final assembly...and that was cheap in comparison to this 2J...do the basic work and you will get the data.

[BigMuz]

Fair enough mate- didn't realise you would run the stock cams first. That makes more sense.

[TK]

Nero - we will be, but as the cams won't be going in till later it'll be hard to check if there is a problem now.
If we were to find out that there would be an issue then I'd flycut the pistons now to avoid issues when the cams go in - hence it's a good idea to find out if there will be a problem as it is something that cannot be physically checked without the cams before the engine is assembled.
BTW - on average I do 1-3 dummy assembles on a 'built' motor before final assembly - the number of dummy assembles depends on what needs to be checked & whether it can all be done in one hit or not.
It would seem that with 268/272 duration 10mm lift is the highest lift that can be safely used without flycutting pistons, that'd be why most cams stop short of 10mm lift - those that don't usually go up to 11mm+, if you're gonna have to flycut pistons it may as well be worth it.

TK

[Nero]

Fair enough, it hadn't been mentioned and I am always sceptical of suppliers advice given that most will not accept responsibility for error.

[Reaper]

Streuth - that's a fair few replies already only next morning.

I think measuring is well and truly in order now. Thanks for replies on this topic re: method - ta!

As regards original development target - all that has really changed is the 1mm os valves which as Tony says would be madness not to do. This was a bit of an unknown at the start but since the BC valves are only 400US an owner would be dumb not to do it as porting costs are still the same ie. now we know about the interaction between valve size and porting it is obvious that everyone kinda should be including this as standard.

Just to really spell this issue out - if there were some really tight turns, or not much meat to take out of the ports you might find that 1mm os valves were redundant, but since the "meat" is there the valves will be able to improve things vastly. This was only able to be ascertained on inspection/porting as you can see. Therefore 2J porting can def. make use of these valves.

TK also showed me some late model STi heads where the oem valves were humungus, much larger compared to the 2J so it is nice that the head supports the addition of larger valves, shame it won't support 2mm bigger! (risky?... ie. sealing etc.)

Bang for buck is suspected to be excellent eg. additional 10+% cfm returns for only the valve outlay.

Everything is still going to stay the same - despite the fact that I would actually like to whack on the HKS Type R FMIC now and the AEM ignition amp too.

To summarise for people who can't be arsed reading my essays (I don't blame them!) the mods list is now this :-

1) flowed head
2) Brian Crower springs and retainers
3) 1mm os BC valves
4) cleaned up block oil galleries
5) ported & clearanced oil pump assembly
6) aero throttle body plate
7) port match/clean runners and plenum
8) port match/clean exhaust mani
9) fresh oem rings (maybe include tweak/balance oem rods? here)
10) ARP HSK, big end, main cap studs/bolts
11) ACL Pro Seal gaskets throughout inc. mls hg
12) pcv pissed off in favour of atmo catch can & ventilated cam covers
13) Titan crank pulley & new belt
14) TRD engine mounts
15) BoostLogic timing belt tensioner bracket (dems brakes)

Timing belt snappages are apparently rare according to Dusty, although I have seen references to them stretching at higher rpms and to put this into a 'ballpark' that means probably 8500+, ie. my targeted 7500 (ie. limited by oem pistons/rods) is apparently not that much speed wise.

PS- re: new rings - this car had a compression test when I bought it some 3 years ago and was very healthy and even across "the top" ie. all 6 cylinders were within 5% of each other and all up around 170/180 psi from memory. I don't believe that freshening the rings will really be a power adder as such but more of a preventative maintenance thing, also just trying to lower chance of blowby for when the car starts running hi boost on better fuel.

[Ze]

Forget the rumours/ internet/ salesman.

It doesn't matter

I fail to see the big worry one way or the other- do they break belts all the time?

Then keep an eye on the belt and change it if you are suss.

I agree with ya

It doesn't really matter but on a matter of terminology , whether an engine is an interference design depends entirely on lift , duration and timing don't matter when it comes to telling if its an interference design or not. It's that way for a simple reason because if you lunch a belt you've got no control over timing anyway , so you can't control timing of the valves in relation to the pistons anymore with a lunched belt.

[Andrew Bolt]

....shame it won't support 2mm bigger.

Been done.

Timing belt snappages are apparently rare according to Dusty, although I have seen references to them stretching at higher rpms and to put this into a 'ballpark' that means probably 8500+...

One thing I have seen fail is the tensioner pulley support bracket - snapped in half. Remedy was to make a billet steel unit.