Jun 2.7l Stroker Build Underway (hks T04z)

[WetGTR]

So really when someone says they are putting 'BIG' cams in, in actual fact they are smaller

<{POST_SNAPBACK}>

No, its just the base circle and has nothing to do with a smaller cam. Its so you can actually make it a bigger cam in the sense because you will not be required to machine the head as much for fitting to obtain that sort of lift.

Tomei also have smaller base circle cams when you wish to use 10.2 lift cams.

I had the HKS cams before (large base circle) and the only difference was I needed thicker shims - HKS cams @2mm shims where Tomei cams were @3mm shims (Tomei being @1.7mm smaller diameter base circle)

In the end it all works the same once fitted with proper shims sizes for valve clearances.

Edited December 15, 2005 by WetGTR

[StageZilla]

well abit more progress in the past few days. we have gaped all the rings, and pistons and rods r installed without a problem

also picked up my head the other day and it has been ported and polished extensively, plus the squash/quench area on the underside of the head has been removed as reccomended by JUN on big power setups. also added a set of tomei cam studs for safety with the large lift.

picking up shims on monday or tuesday and then reassemlbing head.

heres a few pics of the supporting hardware on the engine/driveline. including JUN oil pump, twin plate clutch, 9L baffled sump, etc

cheers

Brad

[Cubes]

Damn. (In awe)

The oil pump topped it off.

EDIT: All this work an no polishing of the combustion chamber? hehe

Its easy to miss the little things.

Edited December 17, 2005 by Cubes

[Bl4cK32]

not if he he hasnt put the head on yet?

[proengines]

Looks like it's all going very nicely! One question, in the photos of the head the quench areas are still there, were they removed after the photo was taken?

[blk180]

Hey StageZilla what type of block are you using

[StageZilla]

hey proengines, i must admit i havent seen a stock rb26 head in over 3-4 months now and i asked for the quinch area to be done as they suggested, and im sure theres no square edge as on the stock head? its been machined out so its all rounded. or am i thinking of the wrong area? anyone got a pic of a stock underside of a 26 head?

stock block is being used at the moment. n1 in the future if it goes pear shaped hehe, i had always thought the n1 block was around 7-8K but i found out they are only like 3k which is pretty decent, but mine had already been machined up by then.

EDIT- well just lookin on JUN website and now i can see it aint been done, as the edges are still square and not the same shape as the bore. god i pay these bloody shops to sort this shit and look what happens, f**kin useless

so would removing the area be a smart idea or what?

Edited December 18, 2005 by StageZilla

[Blitz]

Nice progress, not long now

[proengines]

I'm not 100% sure about removing the quench area, it seems to work on Jun's engines with the power they are making but it will be quite a big difference in compression between what you have now and what you'll have if you remove the pads. We smooth them off and radius the edges and that's about it, I haven't wanted to chop out a customers head just as an experiment. The nice thing about having the pads there is that if the piston runs close enough to the head (.75-1mm) you get a good shockwave that forces the mixture in towards the spark plug where it can burn properly.

It's the old open chamber vs closed chamber argument. At the same compression and timing the open chamber will detonate first. If it was my choice, to drop the compression I would run a flat top piston (or a lower dome) and leave the pads there, just with the sharp edges removed.

What sort of compression are you aiming for?

[Amaru]

Im not too sure on the technical side of things when removing the quench areas, but I did go for a ride in a JUN 2.7L/T51R-SPL kitted R32 GTR the other day which has had the quench areas completely removed. The car drive beautifully on and off boost (and pulled like a friggen freight train as it would on 1.5 bar!), and the workshop that built it (arguably the biggest in Australia) always remove the quench area on their JUN stroker motors if big boost is going to be used.

I sent you a PM about all of this the other day Greg, but am going to pop in to see you this week

[MattSR]

A tuner friend of mine spoke with Koyama himself a number of years ago on this topic - he said that removing the quench pads is only done on customer engines and that it makes the engine less prone to detonation, but it also reduces the combustion efficiency.

[StageZilla]

I'm not 100% sure about removing the quench area, it seems to work on Jun's engines with the power they are making but it will be quite a big difference in compression between what you have now and what you'll have if you remove the pads. We smooth them off and radius the edges and that's about it, I haven't wanted to chop out a customers head just as an experiment. The nice thing about having the pads there is that if the piston runs close enough to the head (.75-1mm) you get a good shockwave that forces the mixture in towards the spark plug where it can burn properly.

It's the old open chamber vs closed chamber argument. At the same compression and timing the open chamber will detonate first. If it was my choice, to drop the compression I would run a flat top piston (or a lower dome) and leave the pads there, just with the sharp edges removed.

What sort of compression are you aiming for?

<{POST_SNAPBACK}>

cheers for the info, mine looks to be smoothed around the valves abit more than stock, and im thinking JUN would supply the stroker kit and pistons suited for the squish area to be removed (like shape of top of pistons).

im aiming for 8.5:1 comp ratio with a 1.2mm metal head gasket

also AMARU can u PM me the name of the shop who did the car u mention and the removing of squish area? thanks..

decisions, decisions..... B)

[Sweetleaf]

The sump you are using gets very bad oil surge at the track,few ppl have panic'd when they see all the smoke at wanners.

[StageZilla]

The sump you are using gets very bad oil surge at the track,few ppl have panic'd when they see all the smoke at wanners.

<{POST_SNAPBACK}>

maitland (sp?) fabrications work that is. i bought it off someone cheap, and just wondering what do the better designed ones do instead? any pics of the good designs?

cheers

Brad

[AlexCim]

Brad, are you selling your RB26 crank and rods?

[Ronin 09]

Brad, does the sump have a door hinge in it??!!?

[Denver]

maitland (sp?) fabrications work that is. i bought it off someone cheap, and just wondering what do the better designed ones do instead? any pics of the good designs?

<{POST_SNAPBACK}>

Maitlands work is usally 20 billion times better than that... however...

You really would want evenish distribution of the oil pan either side of the pickup point..

that instance of the sump you have, has the majority of the oil capacity to one side of the pan, and as pointed out, certainly in the case of waneroo, which has a large amount of right hand turns, all the oil will end up in the left hand side of the sump behind the gate, and given theres only one corner that isn't a right hander, on long track and 2 on short track, it'll probably mean you run out of oil fairly promptly..

ideally..

you want good capacity either side, with a dual gate setup for left and right hand cornering, so a good volume of oil is kept in the pickup area..

id personally have tried to keep the factory baffling setup too and extended it with the gate system, simular to tomei's insump gatesetup for factory sumps..

Im just getting a sump designed atm by a friend of mine, which when completed ill pop some pics up, which should be pretty well functional for racing/drifting requirements, its probably a couple weeks away tho..

cheers

[discopotato03]

I'm interested to know why Jun would remove the quench zones of the chambers . I thought conventional thinking was good quench zones and static CR set by the piston crown . Wouldn't this make for better detonation resistance and combustion efficiency ? A lower "hump" on the crown may help scavenging with with long period cams .

Gary whats your thoughts/experience ?

Cheers A .

[StageZilla]

hey alex yes im selling my original crank and rods, $300 for crank and $250 for rods or $500 for both together if u like

yes the sump has a hinged door.

just wondering should i have a winged side of the drivers side of the sump aswell for another hinged door area? any pics welcome also im using the factory baffling inside the sump as i just removed it for the picture.

[Denver]

Hokay, my mistake there, i was putting more though to this last night, saddly the front diff is an issue for clearance and extending the sump on the right side, in my case it won't be an issue as the front diff is going <r33 gts-t> but even still, you should be able to get some more capacity to the right side of things..