Performance 2T-ZE design

[Radar]

When boring the block from 85mm to 88mm, what needs to be done to the head?
Also when you buy custom pistons you have to know the valve pocket depth, how do you work that out? .511" lift

[jeffro ra28]

Radar, the piston manufacturer work out the valve relief depth when you supply them info such as head gasket thickness, cam specs, valve diameter, deck height, compression height and if they do not have the 2t's chamber shape on file they will definantly require a sample piston or a chamber mould (even if they do they will ask for a sample piston or combustion chamber mould to save any doubts) unless they do them of shelf for 3t's in which you have to check compatibility.

[jeffro ra28]

Oh, and you shouldnt have to do anything to the cylinder head with the 88mm bore. It should infact improve your squish area slightly. Not that the hemi chambers had much of to start with.

You may require a custom head gasket for the larger bore also. Make sure you sort this before ordering pistons as they will need to know HG specs and you may be stuck with very few options for thickness, HG bore diameter etc.

Will the 3t ones work?

[Radar]

The 3T ones will work fine with longer rods, but I doubt BME make off the shelf pistons for the T series motor. They want an order form filled out with what I want.
I've been considering using a cosmetic head gasket from BRD; 1.2mm thick / 3.466" bore? Should squish down to about .040"? I don't want to go to overboard, I'm trying to maintain fairly high compression (10:1)
http://www.bmeltd.com/pdf_files/pistonorder.pdf
And for extra money you can have certain extras done
http://www.bmeltd.com/pdf_files/2008...20Services.pdf
I'm just not 100% on a few things still?
If compression height is:
Block Height(7.758") minus 1/2 the crank stroke(2.755"), minus the rod length(5.200"), minus the deck clearance(0.008")?
7.758 - 1.3775 - 5.200 - .008 = 1.1725
Is this too excessive and will I have pushed the pin into the oil groove?
Ring lands? How thick do these need to be?
Ring Grooves are 1.5x1.6x2.8 I believe?
Not sure on the groove depths?
Also asks for intake pocket depth and exhaust pocket depth?
That's why I assumed I needed to know the valve relief depth.

[jeffro ra28]

Short answer is yes you can push the piston pin into and up to the height of the top of the oil control ring land but you will need to use oil rail supports with your oil control ring. The piston manufacturer should automatically supply you with suitable oil rings with oil rail supports suited for pistons with the gudgeon up as high as the oil control ring land. But some manufacturers require you tick the box in the custom order form for "oil rail supports".

For ring dimensions id go with 1.2 top, 1.5 second, and a 2.8 or 3mm oil.

Also, why BME?

I would get some custom JE's or atleast a piston company that has reps in Australia (Rocket - ARIAS, Performance Wholesale - JE, Hi octane - CP and so on). Especially if your are a little vague about how to fill out the forms.

[Radar]

BME use forged aluminum, one of its main advantages is reduced weight while still maintaining fantastic strength and durability.
Not to mention reasonably cheap.
BME also make forged aluminum rods I want to use them also for the same reasons.
So I kinda thought an all aluminum bottom end would be fairly rev happy and reliable.
(Moldex Billet 4340 crank)
The question isn't if I can push it into the oil ring, its am I GOING to?
I don't want to put the pin in the oil ring, I just want to find what the max is I can go before I'll reach it up against the bottom of it. (Chasing a high rod/stroke ratio)
I need a labeled diagram of a 3t or 2t or 2tg piston with measurements if it exists?
I'll keep plodding along until I figure out the forms 100% but until I can anyone that knows and could give us some tips it would be much appreciated.

[jeffro ra28]

Despite BME's fancy marketing speech, there really isnt any noticeable performance difference between their product and any other forged piston manufacturer. The only thing you may notice is a difference in piston-bore clearance specs which is mainly dependent on the silicon content of the aluminium used.

If this engine is designed to be used for endurance then do not use aluminium conrods. They do not and cannot withstand the amount of heat cycles that a steel connecting rod does. They are designed for drag race engines only and have absolutely no place in an endurance engine of any kind. So unless 1/4 mile drags are your thing, i advise strongly against the use of aluminium conrods. Plus you will not notice the difference. If you have no budget and really want lightweight then go titanium rods but be prepared for a price tag upwards of 1k per rod.

If it were me going to all the effort of custom pistons, id put the longest dam conrod in the engine that the piston would allow. Why are you worried about whether or not the gudgeon pin enters the oil control ring land? The only real disadvantage is having to pay $24 for a set of oil rail supports and spending a whoping extra 3 minutes to assemble your rings on pistons.

[Radar]

This is why I ask questions to stop me doing silly things... Ok so CP? Wiseco? JE? all good stuff?

[jeffro ra28]

JE, Wiseco, CP, mahle, all good gear. ARIAS are O.k, not as good as the others but is a bit cheaper.

Its good that your giving it a go, its the best way to learn, but if its your first time measuring up an engine for custom bits then you need some guidance. Is there a speed shop close to you that can talk you through and or source the pistons for you?

Do you own any measuring gear?

[Radar]

Haven't even thought about talking to a speed shop yet, maybe its time to pay them a visit before I go spending money.. Nah no measuring gear, I intended on buying the parts and getting a shop to put it together for me. I'll have a ring around tomorrow thanks for the help man.

[jeffro ra28]

Best advice i can give is to go to a shop that has a known reputation with older toyota motors. Not the biggest baddest V8 engine builders etc.....

[Ical]

Any recomendations on such a workshop.

Thanks Ian.

[jeffro ra28]

I know Rod (Thetoyman75), and a few other 2tg and 18rg nuts know of a few. Maybe they will tune in.
I do my own however but have not had years of experience with them at all.

[Radar]

How much cranking pressure is too much when your adding boost?
I'm under the thinking that if I have a cranking pressure of 180~200psi that will be the upper limit.. I'll be running 10.5:1SCR (196 cranking psi) with 10psi..
Will this be too brutal and just cause mass detonation...?
I'm fairly confident in my fuel being sufficient with two rows of brown dot 100cc LPG injectors good for up to 330kw (105~+/- octane & freezing).
So yea what are the upper limits of cranking pressure when adding boost and working with only 104~108 octane fuel??
Also
When it comes to forced induction its better to have bigger ports and valve lift rather than less right?
Also
What would happen if I were to ceramic coat the piston face, combustion chamber, exhaust port, and both valve faces?
Could it improve combustion and reduce detonation?
I think I read somewhere that its either the combustion chamber coated or the piston face... Not both? But I don't Know?

[allencr]

How much...
I'm under the thinking...
Will this be too brutal ...
I'm fairly confident ...
So yea what are the upper limits...
When it comes to forced induction...
What would happen...
Could it improve...
I think I read somewhere...

Read A lot more stuff. Looking at that 'cranking pressure' thing, I know there's gotta be a lot better stuff out there to read.
No, the compression ratio is an exact fixed number and there is nothing 'theoretical' about it. Yes, the intake valve/s do not close at BDC and some close a lot later then others, End of story, no magic.