Alright. They are the same bore and stroke. Does the lower compression come from a dished piston or combustion chamber differences, head gasket thickness, or a little of each. After quite a bit of searching, I havent been able to find information on combustion chamber CC's or head gasket thickness. I'm guessing the ring lands would be lowered on the VG30dett pistons to help prevent cracking, but if the differences are spread through the head, headgasket, and piston, what would the static CR be with these pistons in a VE block? Any info would be cool. Also, are the VG30dett pistons forged or cast?

 

I'll look tommarrow.
Not sure on the CC size.

 

Well think about it.
It can't come from the head's cc as you use the same head
It can't come from the headgasket as you use the VE one and there isn't a thicker on available that I know of.
It's either a dished piston to add CCs to the total combustion chamber volume. Or the wrist pin is located higher in the piston.

 

the VG30DE/DETT and VE30DE use the same head and head gasket?

 

No they don't. What HG do you use before and after the install?

 

Hi,

the VG30DE/DETT have the same head setup as the vg30e,

the ve30de does not have the same head setup as the vg30e,

 

maximagxe90, no. The VG30DE/DETT head is not the same as the VG30E.

Jeffy I dont understand your first post lol. He is basically trying to figure out if you put VG30DETT pistons in a VE if it will have the same 8.5cr as the VG30DETT.

 

sir...put the crack down and step away from the keyboard

 

stoopid noobs. the VG30E just has TWO heads to the VE30DE and VG30DETT, because they're both DOHC engine. the VG30E is only SOHC, so it must have two heads on each side to fit all four cams in and make them the same.

 

Lowered compression comes from at least the piston because it is dished. Headgasket is probably gonna be the same as any other nissan. That is a cheap way to lower compression, a route most engineers wouldn't take. Combustion chambers for both of the heads is the same (49.5cc). Ring lands are they same hieght also, I had both VE piston and VG30dett pistons in front of me at one time, and they were very similar including the lands. The pistons are cast stock.

If you could find out the VE head combustion chamber and the dished volume of the Dett piston, you could find static CR.

 

Hi,

ok then vg30de/dett will not work with the vg30e,

but the vg30de/dett have the same head setup as the vg30e,

could it be possible that the vg30de/dett piston fit in the vg30e?

i must been sleepy when i post that last message,

 

1 - true - head will not work..IE interchange...i believe they can be BOLTED to the block (see 3)
2 - false - VG30DE/DETT have DOHC...VG30E have SOHC
3 - true - block is "pretty much" the same.
4 - VERY true

 

Ok, considering the fact that the stock VE piston adds no volume to the combustion chamber since it is flat with the block at TDC, calculating the cylinder head volume is very easy.

We first need to realize that the CR is just the ratio of volumes of the cylinder + head cc/ head cc = 10:1. Cylinder volume is pi * (bore diameter/2)^2 * stroke.

Cylinder Head volume = X
(3.1415926 * (8.7cm/2)^2 * 8.3cm + X) / X = 10

Solving for X gives us 49.34cc's for Combustion chamber. Although this is not the 49.5 I have seen (for both the VG and VE, supposedly have the same head cc's), there is also some more volume to be added when the headgasket is brought into play, which could very well be the .16 cc's we are looking for.

With all this said, seeing as how bore, stroke, and head volume is same for both motors, this means that the compression ratio for both motors is going to be the same for the same piston.

So yes, the VE will be 8.5:1 compression with Twin Turbo Z pistons . And yes pat, the VE will be 10.5:1 compression with NA Z pistons too.

 

Hi,

would the vg30de/dett piston fit the ve30de engine?

if the piston fit the block on the vg30e,

would it fit the block on the ve30de engine?

does the vg30de/dett have the same size piston as the vg30e?

 

would the vg30de/dett piston fit the ve30de engine?

if the piston fit the block on the vg30e,

would it fit the block on the ve30de engine?

does the vg30de/dett have the same size piston as the vg30e?[/QUOTE]



Yes they do, this has been proven by myself and MadMax024.

The bore and stroke are the same, and considering all the above stated, and how the ve is similar to the VG30de/tt, the vg is probably the same case.

 

1 - according to the 1st post...yes. personally i'm not 100% sure...i heard it does fit.

2 - piston will fit the VG block.

3 - size...i wouldn't say the overall size would be the same due to difference in CR. someone would also need to confirm this.

 

Thank you Julio and everybody else with info. Does anybody have a rough estimate what kind of power Z guys are producing before forged pistons are needed? I'm guessing it's pretty high, from what I've read about Nissans engineering and production.

 

Thank you Julio and everybody else with info. Does anybody have a rough estimate what kind of power Z guys are producing before forged pistons are needed? I'm guessing it's pretty high, from what I've read about Nissans engineering and production.[/QUOTE]

Well, its not as simple as that for a couple of reasons. Stock pistons are very strong when it comes to power. I have seen guys producing 500whp is some cases, and heard that 600whp is about their limit. But seeing as how these pistons are cast, they arent strong when it comes to detonation. When entering the the realm above a stage 3 Z, these pistons wont last long if you arent very careful. Most Z guys who are stage 3 have maxed out their turbos (350-380whp), and dont have to worry about pistons unless they get frisky. Most people who opt to get bigger turbos for more power beyond stage 3, end up shelling out cash for the pistons. This is because the motor has to be pulled in most cases to upgrade turbos, and the cost of the pistons themselves are relatively cheap compared to the rest of the supporting mods for the bigger turbos and power. Thats why its hard to find any guy with a Z who got cheap and didnt put in pistons, and is running more than 500whp.

If you are looking to make just under 400hp, these are your pistons to get, because you can find them cheap (mine were 120 w/2k miles on them). But if you have plans for any more than that, def get forged ones, cause you can find them for $550 on TT.net. Rods are good to 600whp too, so dont worry about those.

 

Thanks again.

 

Please put the keyboard and the wrenches down. Take your car into the shop for any required service.

Fitting IN the block is completely different than FITTING.
the bore is the same on them, but the wrist pin diameter on the VG30E is smaller than the VE or VG30DE. Thus Z pistons will not work- unless you do work to the connecting rods or to the pistons themselves. $$$ in either case.

 

julio i know you said the VE and VG30DETT rods look identicle, but are the part numbers the same

 

YES, they are the same part number. It's been verified about a zillion times.

 

i ordered some TT pistons and rods as well as a crank for my spare VG30E. i have no doubts that everything will fit but I'll let you guys know when I actually get them in.

the only thing that won't directly bolt in correctly is the crank. the snout needs to be machined so that all of the maxima stuff can fit on (timing belt sprocket, crank pulley, and i think the oil pump).

 

Where's the deck height addition?

 

restating everything:
for the VG30E: you need VE/VGDE rods and wristpins. then you have your pick of pistons, anything that fits a Z/VE will work in the SOHC VG block with the corresponding rods.
for the VE: any Z pistons, rods, wristpins will work.

all that being said, anyone want to build a high compression SOHC VG? i've still got my VE pistons and wristpins. no noticable problems, i'm almost positive julio has his Z32 pistons..hmm??

 

not for long

 

errrr i meant rods..i know hes still got the pistons.

 

anyone got some Wiseco TT pistons bored .5mm over for sale?

 

Where's the deck height addition?[/QUOTE]



What the blazes are you talking about, explain yourself.

 

http://www.rbracing-rsr.com/squishcalc1.html
http://www.2strokeheads.com/Deck_Height.html
You must add (or subtract) deck height when you do head CC computations.

 

Hey Jim, I've also had to calculate the little area inbetween the top of the piston to the 1st ring.

 

hmm I was never asked that when ordering pistons. I know they'd ask for compression height, but I can't see why they would ask for that.
Is that for a stock replacement?

Julio: I'm not saying your wrong, DH could be zero and your computation is fine.

 

"Ok, considering the fact that the stock VE piston adds no volume to the combustion chamber since it is flat with the block at TDC, calculating the cylinder head volume is very easy."

I already stated this before. I believe this is what you were refering to. Correct me if I am wrong. But yea, i know you are just making sure. When it comes to engine stuff, you definitely want to get it right. As for the volume to the first ring, I would think that would be important too, but small none the less.

But considering that i have heard that the chambers have the same volume, and my numbers were so close, that the computation was correct. Cant be for sure until a head is taken off and measured though, unless someone can get ahold of some nissan tech info.

 

I guess I missed that (doh). But how did you find that? I remember researching a couple years ago for that info and I couldn't find it. Did you measure it yourself?

 

What kinda numbers you looking for, exactly?

The FSM doesn't mention it, nor do the SAE papers written about the development of the VE.
But I DO have a spare set of heads off the car.
the block is torn down so I cant check that.

I also have a VG30E that's been torn down.. the valves are bent, so I can't get a good volume of the head, but I can check the deck height- the pistons are still in the block.

 

When I rebuilt my motor, I rotated my motor so that one of my pistons was at TDC, and it was without a doubt in my mind totally flat with the block. I mean, it could have not been flush by just a little, but it seemed so close in my opinion that it was flush.

-Matt, I was just looking for the volume of the combustion chamber to compare to a vg30de/tt so that I could make sure that my TTZ pistons actually lowers my compression to 8.5:1. Although some some real evidence (volume test) would re-assure my opinion that they are infact the same volume, it would only be a re-assurance due to my calculations.

 

I have some good heads sitting in my garage that I can check. I've been wanting to actually since I want to see the difference between these and the Z32 heads so that I can get an idea of what the compression will be. I'm kind of hoping for closer to 9:1 but if it stays at 8.5:1 I'll be happy.

Shawn, I'm still trying to find how close the valves come to the pistons when at TDC but I'm having a hard time finding my crap set of new head gaskets. (dang things got damaged in shipping but I got a replacement set for free. There was one spot on both gaskets that got torn off which would have allowed oil to just squirt out the side. They should be able to give me a correct measurement though.)

 

they're going to compress when you bolt them down to the car. at least they will a small amount.

as far as valve clearance at TDC.. I will tell you that there's not enough with the OE pistons if you break a timing belt. at least 10 of the 12 valves on the VG30E were bent from snapping a belt at 3000rpm.

 

You have a PM