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Discussion Starter #1
I have decided that if I get a built shortblock, which may be within my budjet at the moment, that I'm going to need custom pistons. I want high compression (11:1-13:1). I'm gonna run propane as the startup/idle/cruise fuel, switching to pure methanol (with perhaps 5-10% water mixed in), during boost. Both of these are high octane fuels, and I can use higher compression to get better response, power, and spool. However, there are no high compression off the shelf pistons for the 2JZ.

I called JE, and can get their normal 2JZ pistons at 11:1 compression for $1100/set, including rings.

I think I remember hearing that some of the usually more expensive piston makes (Weisco, Arias, etc), make every set of pistons custom anyway. I'd figure in that case, it shouldn't be any more for one compression ratio than another, if they are all made to order. Anyone confirm this?

Disclaimer: I ask the usual "don't do this because it's not done" people to refrain from lecturing me on why I shouldn't run higher compression.
 

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You might also consider running a NA headgasket to get yourself a bit more compression. Or you could mill the block or head although a HG would be much more preferred. 11:1 up 13:1 is REALLY high though. If you combine the 11:1 pistons with the NA Headgasket then you will probably be looking in the area of 12:1 compression or somewhere around there.

Good Luck working out the fuel system.

Later,
 
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Discussion Starter #3
You happen to know the difference in installed (ie torqued down) thickness between the stock NA and TT gaskets? I thought they used the same gaskets, but the NA has different pistons.

There any difference between the NA and TT head volumes (in ccs)?

Ideally, I'd like flat top pistons, then use the correct gasket to get to my target compression.

Yes, 13:1 is crazy, but with propane or methanol as the only fuels, I have lots of octane. I'm probably gonna settle around 12:1.
 

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Derek, Check out Arias pistons as I think they offer the higher compression made ones.

Adam
 

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Adam, I think the arias you are referring to are the 9.5:1's. AFAIK that compression was because their data showed an incorrect number for our combustion chamber making their pistons have a higher compression based on that number...using the true number I believe it was like 8.9:1. Although, you could be talking about different ones.
 

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AnArKey said:
You happen to know the difference in installed (ie torqued down) thickness between the stock NA and TT gaskets? I thought they used the same gaskets, but the NA has different pistons.

There any difference between the NA and TT head volumes (in ccs)?

Ideally, I'd like flat top pistons, then use the correct gasket to get to my target compression.

Yes, 13:1 is crazy, but with propane or methanol as the only fuels, I have lots of octane. I'm probably gonna settle around 12:1.
If im not mistaken then the TT are I beliebe 1.6mm or 1.2mm I cant quite remember. And the NA I believe is something like 0.3mm so there is DEFINATELY a difference there. But you are correct in the heads being different as well. The NA heads are a tad different but I dont think the volume is any different. The NA and TT pistons and rings are the same.
 
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Discussion Starter #7 (Edited)
Wow.....really? You SURE the NA and TT pistons are the same? That's TOO cool! So I can get NA compression ratio just by using a NA head gasket? That saves me a LOT of trouble. I'd be happy with just a 11:1 ratio from a NA gasket and milling the head just a touch.

The math doesn't agree however. Assuming a 1.6mm gasket gives a 8.5:1 ratio, a .3mm gasket will only bump it to 9.5:1. Either the pistons ARE different, or the NA head has less volume. FYI, using the same gasket, same head cc, but a near flat top piston gives me about 10.5:1, which is what the NA's compression is.
 

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NA pistons are different. The top ring land is thinner (weaker), for one. I believe the head volume difference is 2cc. 42cc for the GE and 40cc for the GTE but do a search just to be sure. I access to both GTE and GE heads, so if you need some asistance (or want one) let me know.

Ryan
 

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Have you thought about using the GE head? In your app, I think it would be beneficial. The throttle body would be 8~10"away from the compressor outlet. The GE head has much larger exhaust ports (round) and the exhaust ports are a straight shot from the valve (unlike the GTE head). Of course the exhaust manifold would have to change. I think Lar makes a GE tubular header though. The cam position signal can be handed off to the EMS via a MKIII GTE CPS (no distributor). The intake ports are a little smaller but the valves are the same size. The lower GE intake runners are .100 larger than the GTE lower. The runner length is within 1/4" between the two although the bolt pattern is different. The upper plenum's volume is close to the GTE when you factor in both sections. The GE intake also has the ACIS variable runner length flapper. The EMS could perform that function quite nicely. I picked up an SC300 head/intake for my IS project but decided against it due to I/C pipe routing issues. I'm now going to use the GTE head/intake/throttle body.

Just some thoughts....

Ryan
 
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Discussion Starter #10 (Edited)
I was planning on using a GE head actually, for the reasons you listed. Hoping to get a VVTI head, and have the EMS control the intake cam.

I really don't like the GTE cast manifold, but love the Toyomoto GE cast manifold. There's one reason.

I wouldn't run the stock GE runners or intake manifold though, it's too restrictive. Gonna build a sheetmetal manifold.

If I ever make my steam powered or other experimental "on demand" turbo a reality, the cheap and readily available normal NA headers for the GE will also be ready, rather than needing something custom and expensive. I'm actually getting a set in a buy going on right now, as I plan to have a SC300 someday. May be within a few months if I "get the job."

I'm pretty set now on building up a shortblock. Bought some Eagle H-beam rods. Now to get some custom flat top pistons. I have a spare GTE shortblock sitting in my garage I can build. Then I can sell my entire existing GTE, and top the new built shortblock with a GE head, which I can port. Also gonna have the piston tops, combustion chambers, exhaust ports, and Toyomoto manifold Swaintech TBC coated.

The car is mostly apart, so taking out the engine/tranny together now would be easy.
 
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Discussion Starter #11
OK, I have done some further number cruncing, and I think I got it figured out.

Second hand data:

TT gasket installed thickness: 1.3mm
NA gasket installed thickness: .3mm
TT head volume: 45cc

I know the TT pistons are dished -14cc. This is from several piston makers.

Assuming a 0 deck height (pistons flush with top of block), it calculated to 8.5:1 exactly. So the data sounds just about right.

Someone else posted that the NA head is 42cc. This was measured carefully.

I can only assume that the chamber is shaped differently, so that correct squish/quench is maintained on the NA head, with zero deck, and the paper thin .3mm gasket.

So if I was to get flat top pistons, which would actually be -2cc for the valve reliefs, run the NA gasket, and a NA head, I'd get a compression ratio of 11.92:1, just about right.
 

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Give Venolia a call. They will make you anything you want. They are in the process of making me a custom set of Big block chevy pistons for a turboed big block truck we have. They are also very reasonable. We paid roughly $680 for a set of 8 custom made pistons and tool steel wrist pins from them. http://www.venolia.com/ Oh and if it makes you feel any better we have run 11.5:1 compression in a Local buddies Pro-modified drag car on straight methanol and a BDS 12-71 supercharger making 40 lbs. of boost. Drew
 
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Discussion Starter #13
40lbs boost and 11.5:1? Kick ass! Methanol rocks.

I'll call Venolia about some pistons too. Gonna give Ross a try too.
 

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AnArKey said:
40lbs boost and 11.5:1? Kick ass! Methanol rocks.

I'll call Venolia about some pistons too. Gonna give Ross a try too.
Venolia is your best bet. You just have to fax back their order form that you download off the website. And yes, methanol does kick ass, did I mention 3500 HP? Drew
 
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3500HP? Must have been flowing methanol like it was coming out of a garden hose!
 

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Oh yeah 5-6 gal per run depending on the burnout and warmup times. BTW that was bigger than a garden hose, 1 1/2" fuel line ;)Drew
 
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Discussion Starter #17
AnArKey said:


I called JE, and can get their normal 2JZ pistons at 11:1 compression for $1100/set, including rings.
compression.
1100 seems high for je pistons
go with JUN (cossworth) pistons they are $1500.
 

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Ross and CP are both good... CP are lighter and have a stronger availible wrist pin(the heavy duty one) I dont see ANYONE breaking this wrist pin.. its pretty crazy:)

Also I wouldn't run the na headgasket because its too thin imo. The multi layer tt hg is much stronger. I've never measured the actual piston but I think the na pistons is about a 6-7cc dish based off other calculations.

Lemme know if you are interested in cp pistons... Much cheaper than your je quote:)
 
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