How are gte pistons are less compression?
11-27-15, 08:20 PM
#1
How are gte pistons are less compression?
http://www.supraforums.com/forum/sho.../680149?page=1
I have studied and studied this forum and for the life of me I can't figure out how the piston reduces the compression. They are the same hight, they valve pockets areally just a little different, the combustion chamber is relativity tighter in the gte head so I would think n/a head is lower compression on that, the cc per piston is not even 7cc's different. So I can't figure it out. The top piston ring starts in the same place but is a little wider. The piston pin is in the same place. Idk.
I am buying gte pistons because I hear over and over that they are lower compression but Idk how.
Does anybody know if I do install gte pistons what my compression ratio will be with ge head gasket vs gte head gasket. Both factory.
Also, does anybody know what the squish ratio would be with the gte pistons and ge head gasket vs gte head gasket? Please help as I'm trying to build an efficient motor that last long and I don't have to go back into it to often.
I have studied and studied this forum and for the life of me I can't figure out how the piston reduces the compression. They are the same hight, they valve pockets areally just a little different, the combustion chamber is relativity tighter in the gte head so I would think n/a head is lower compression on that, the cc per piston is not even 7cc's different. So I can't figure it out. The top piston ring starts in the same place but is a little wider. The piston pin is in the same place. Idk.
I am buying gte pistons because I hear over and over that they are lower compression but Idk how.
Does anybody know if I do install gte pistons what my compression ratio will be with ge head gasket vs gte head gasket. Both factory.
Also, does anybody know what the squish ratio would be with the gte pistons and ge head gasket vs gte head gasket? Please help as I'm trying to build an efficient motor that last long and I don't have to go back into it to often.
11-27-15, 09:40 PM
#2
The GE and GTE heads should roughly be the same. The difference in the pistons is the dish in the piston top. The deeper the dish, the less compression. The piston pics are a little misleading because they don't show depth that well. The other thing is, that the gte head looks to have been heavily machined, where the GE head hasn't
Last edited by pogoism9; 11-27-15 at 09:44 PM.
11-27-15, 11:11 PM
#3
I caught on about the compression ratios and squish effect at the bottom of the first post.
How does one get 8.5:1 compression ratio out of ge or na/t with the proper squish effect? Changing to even smaller pistons? I know smaller rods (not really feasible because they'll be too low and not enough compression to make an explosion inside cylinder) is one method, like those of 1jz.
Thanks pogoism. I really can't see any difference in the dish.
How does one get 8.5:1 compression ratio out of ge or na/t with the proper squish effect? Changing to even smaller pistons? I know smaller rods (not really feasible because they'll be too low and not enough compression to make an explosion inside cylinder) is one method, like those of 1jz.
Thanks pogoism. I really can't see any difference in the dish.
11-28-15, 01:11 AM
#4
Grumpi,
First of all, are you absolutely set on 8.5:1 for any particular reason or would you be okay with something close to that, anywhere between 8.7:1-9.2:1? Because you can get to a compression ratio within that range with your GE head and GE pistons which are exactly the same strength as GTE pistons. They simply lack the more aggressive dish in the NA application. The rods are also exactly the same as GTE rods and thus equally as strong. This applies to any 1992-1997 2JZ-GE engine. (*For a 1998-2005 GE block, the rods and pistons should be replaced).
Three things are at work to reduce the compression of the 2JZ-GTE engines:
-The GTE pistons have a more pronounced dish.
-The GTE head gasket is 1.3mm and is Multi Layer Steel. The GE head gasket is MUCH thinner at something like .3mm (I cannot recall the exact number, sorry) and may not be MLS.
-The GTE has a slightly different combustion chamber than the GE head. Ali explained this to me a while back as I had asked his advice on aftermarket head gaskets and suffice to say I'd have to reiterate his explanation from my notes but it is significant enough to further influence the compression and squish.
Barring some rule that says I can't, I will be getting my 2JZ-GE block with the factory pistons as close to 8.5:1 as I can by swapping over a 2JZ-GTE head (not needed as per your question but I have to in my case), and by using an HKS "Stopper" 2.0mm head gasket or a Tomei 2.0mm gasket. Cometic was my original choice but they apparently stopped making theirs in 2.0mm thickness. In my case, depending on how the rebuild and inspection of my GTE head goes, I should be able to get to 8.6:1 or 8.7:1 without compromising optimum squish.
There is also a 2.4mm head gasket size from Cometic. Possibly HKS or Tomei too. That can get you below a 9.0:1 if you need this. Although I would defer to Ali SC3 or Gerrb on the math to determine the most appropriate one because 2.4mm is getting up there.
But you don't need to replace your GE pistons to get very close to your goal in most cases.
First of all, are you absolutely set on 8.5:1 for any particular reason or would you be okay with something close to that, anywhere between 8.7:1-9.2:1? Because you can get to a compression ratio within that range with your GE head and GE pistons which are exactly the same strength as GTE pistons. They simply lack the more aggressive dish in the NA application. The rods are also exactly the same as GTE rods and thus equally as strong. This applies to any 1992-1997 2JZ-GE engine. (*For a 1998-2005 GE block, the rods and pistons should be replaced).
Three things are at work to reduce the compression of the 2JZ-GTE engines:
-The GTE pistons have a more pronounced dish.
-The GTE head gasket is 1.3mm and is Multi Layer Steel. The GE head gasket is MUCH thinner at something like .3mm (I cannot recall the exact number, sorry) and may not be MLS.
-The GTE has a slightly different combustion chamber than the GE head. Ali explained this to me a while back as I had asked his advice on aftermarket head gaskets and suffice to say I'd have to reiterate his explanation from my notes but it is significant enough to further influence the compression and squish.
Barring some rule that says I can't, I will be getting my 2JZ-GE block with the factory pistons as close to 8.5:1 as I can by swapping over a 2JZ-GTE head (not needed as per your question but I have to in my case), and by using an HKS "Stopper" 2.0mm head gasket or a Tomei 2.0mm gasket. Cometic was my original choice but they apparently stopped making theirs in 2.0mm thickness. In my case, depending on how the rebuild and inspection of my GTE head goes, I should be able to get to 8.6:1 or 8.7:1 without compromising optimum squish.
There is also a 2.4mm head gasket size from Cometic. Possibly HKS or Tomei too. That can get you below a 9.0:1 if you need this. Although I would defer to Ali SC3 or Gerrb on the math to determine the most appropriate one because 2.4mm is getting up there.
But you don't need to replace your GE pistons to get very close to your goal in most cases.
Last edited by KahnBB6; 11-28-15 at 02:46 PM. Reason: Correction.
11-28-15, 06:54 AM
#5
Kahn. No im not dead set om 8.5:1. Im just wondering in case me or other people out there did want to reduce compressiom to 8.5:.
It seems like just using the gte pistons and a ge head gasket drops compression to 9.0:1 and maintains proper squish. I'm OK with that and is actually great.
It is my understanding that gte pistons and headgasket significantly reduces the squish. I'm just trying to look for the happy medium.
It seems like just using the gte pistons and a ge head gasket drops compression to 9.0:1 and maintains proper squish. I'm OK with that and is actually great.
It is my understanding that gte pistons and headgasket significantly reduces the squish. I'm just trying to look for the happy medium.
11-28-15, 02:55 PM
#6
^^ Did you mean to type "GTE head gasket"? I haven't heard of anyone using a GE NA head gasket for a turbo application, though I could be wrong. Usually people suggest the factory Toyota TT 1.3mm head gasket at minimum with an NA-T.
You've got it right though. The end-all best solution is to swap out the GE pistons for GTE pistons or any aftermarket GTE piston with a compression ratio of your choice (8.5:1 through 9.2:1 or thereabouts depending on the build type, intended fuel and ECU/tuning choice). It's just that this gets expensive and is a lot of extra work when it's just easier and well proven in the SC and MKIV communities to find a happy medium with the factory 92-97 GE pistons and rods and a thicker aftermarket head gasket for a lot of folks since both versions of the short block and rotating assembly are equally strong and capable.
Yes, swapping out pistons and mostly rebuilding/reconditioning the bottom end does make things more optimum. It's just not a necessary step for most owners unless a big custom engine build is required, at which point new pistons and rods would be factored in anyway.
I'm interested to see what your solution will be regardless.
You've got it right though. The end-all best solution is to swap out the GE pistons for GTE pistons or any aftermarket GTE piston with a compression ratio of your choice (8.5:1 through 9.2:1 or thereabouts depending on the build type, intended fuel and ECU/tuning choice). It's just that this gets expensive and is a lot of extra work when it's just easier and well proven in the SC and MKIV communities to find a happy medium with the factory 92-97 GE pistons and rods and a thicker aftermarket head gasket for a lot of folks since both versions of the short block and rotating assembly are equally strong and capable.
Yes, swapping out pistons and mostly rebuilding/reconditioning the bottom end does make things more optimum. It's just not a necessary step for most owners unless a big custom engine build is required, at which point new pistons and rods would be factored in anyway.
I'm interested to see what your solution will be regardless.
Last edited by KahnBB6; 11-28-15 at 03:00 PM.
11-28-15, 05:45 PM
#7
I'm just a kid and don't have big hp goals. I've just always been a big believer in better safe than sorry. In this case, building a block that can handle 800hp but only wanna push around 5 to 6 hundred daily. I want pauter rods no matter what. Carillos are a second option but I don't want lighter weight rods since I have a lightweight flywheel and want lightweight pulleys, (alt, water pump, and power steering.) Gotta keep that rotational mass going. Lol.
Right now I already ordered two pistons from Toyota for 65 each(my price). Once I get paid I'll get the rest 4. Then wanna line hone,
drill and weld bugs for turbo oil drain and
take my block to get the oil galleys drilled for oil feed on exhaust sidea of block. Just a couple of things i want.
But the only thing I have never understood was about the Pistons vs gasket. I don't want aftermarket pistons cause gte's are proven for up to 800 I believe. Theyre lower compression than ge. And aftermarket forged tend to slap when cold. I don't want that.
Rods are strong also but I have seen them bend. Granted they still work, but why would I risk it if I'm already taking the motor apart anyways.
Also, I do believe it's ge block, head, and gasket with gte pistons. That's what it says on the very bottom of the first post on supraforums.9.03:1 compression with factory .045" squish.
Right now I already ordered two pistons from Toyota for 65 each(my price). Once I get paid I'll get the rest 4. Then wanna line hone,
drill and weld bugs for turbo oil drain and
take my block to get the oil galleys drilled for oil feed on exhaust sidea of block. Just a couple of things i want.
But the only thing I have never understood was about the Pistons vs gasket. I don't want aftermarket pistons cause gte's are proven for up to 800 I believe. Theyre lower compression than ge. And aftermarket forged tend to slap when cold. I don't want that.
Rods are strong also but I have seen them bend. Granted they still work, but why would I risk it if I'm already taking the motor apart anyways.
Also, I do believe it's ge block, head, and gasket with gte pistons. That's what it says on the very bottom of the first post on supraforums.9.03:1 compression with factory .045" squish.
Trending Topics
11-28-15, 06:10 PM
#8
http://forums.probetalk.com/showthread.php?t=1701218140
Here's one page. Not the first and certainly not the last. So I want to prevent against that. Granted he was pushing 35psi and 100 shot, neither of which I plan on.
Here's one page. Not the first and certainly not the last. So I want to prevent against that. Granted he was pushing 35psi and 100 shot, neither of which I plan on.
11-29-15, 07:05 AM
#9
Grumpi , if I may ask , what will be the use or purpose of the car you are building ?
One usually should build the short / long block based on its use. Will it be a drag car , daily driver with occasional drag strip use or just plain daily driver ? That should dictate what kind of internals you need to use so it will be reliable and can handle the abuse based on the intended use of the car.
Stock 2jzge / 2jzgte short blocks will handle 500-600rwhp all day safely / reliably with the right ECU and tune. It is a different story if it is a totally drag car where it is continually abused and pushed to its limit to break into a particular time slip just like the car on the link you posted on the previous post.
Torque is what bent those rods . 35psi / 100 nitrous shot is no doubt too much for stock rods. With the right combination of add on parts on a stock 2jzge / 2jzgte long block , one can get to the 700rwhp RELIABLY without bending rods... of course with the right ECU / tune / tuner to help keep the engine safe. There is just too much variables when one is building an engine.. but it has to start in knowing where or how will the engine be used.
I would save my comments later on you saying not wanting a lighter rod like the carrillos since you have a light flywheel once you have informed us what the car is meant for. Before you know it , depending on the use of the car , you might not even need aftermarket internals most especially if you are working on a limited budget. If sky is the limit with funds, then by all means build the engine with all the bells and whistles.
One usually should build the short / long block based on its use. Will it be a drag car , daily driver with occasional drag strip use or just plain daily driver ? That should dictate what kind of internals you need to use so it will be reliable and can handle the abuse based on the intended use of the car.
Stock 2jzge / 2jzgte short blocks will handle 500-600rwhp all day safely / reliably with the right ECU and tune. It is a different story if it is a totally drag car where it is continually abused and pushed to its limit to break into a particular time slip just like the car on the link you posted on the previous post.
Torque is what bent those rods . 35psi / 100 nitrous shot is no doubt too much for stock rods. With the right combination of add on parts on a stock 2jzge / 2jzgte long block , one can get to the 700rwhp RELIABLY without bending rods... of course with the right ECU / tune / tuner to help keep the engine safe. There is just too much variables when one is building an engine.. but it has to start in knowing where or how will the engine be used.
I would save my comments later on you saying not wanting a lighter rod like the carrillos since you have a light flywheel once you have informed us what the car is meant for. Before you know it , depending on the use of the car , you might not even need aftermarket internals most especially if you are working on a limited budget. If sky is the limit with funds, then by all means build the engine with all the bells and whistles.
11-29-15, 07:25 AM
#10
I would daily it during the summer since it has no heat during the winter. Lol. Welded the heater core hold shut. During winter park it or just go to drag or drift events. But yeah I would take it to some drag events but mostly drifting.
Sky is not the limit with funds but I'm not gonna hold back on it either. I don't have a number per se. Right now I see a minimum of 10k since I still have to buy aem v2, xs power ffim, gm lq9 coil kit from suprastore, intercooler, turbo kit, solid diff and rear subframe bushings, custom driveshaft since mine is too long, coilovers, bc 264 cams, 1000cc injectors, dual tt fuel pump set up, and more. Those are just the basics.
Sky is not the limit with funds but I'm not gonna hold back on it either. I don't have a number per se. Right now I see a minimum of 10k since I still have to buy aem v2, xs power ffim, gm lq9 coil kit from suprastore, intercooler, turbo kit, solid diff and rear subframe bushings, custom driveshaft since mine is too long, coilovers, bc 264 cams, 1000cc injectors, dual tt fuel pump set up, and more. Those are just the basics.
11-29-15, 07:52 AM
#11
First , let me move this thread to the performance / maintenance section where it should be.
For budget purposes, let us limit this discussion to the long block ( short block / head) only since all the other bolt on parts costs would depend on what you are getting thus costs can bring you way up there. And I believe the thread is about having a strong / reliable long block that would support the intended use.
If your budget is at least $10k for the long block , you should be able to build a stout long block with aftermarket internals that would support at least 800rwhp reliably for the intended use you mentioned.
With regards the Carrillos saying you don't want a lightweight rods ... generally , the lighter your whole rotating assembly the better. Lighter rods doesn't mean they will easily bend. I just wonder why you didn't want the Carillo rods being lighter ?
For budget purposes, let us limit this discussion to the long block ( short block / head) only since all the other bolt on parts costs would depend on what you are getting thus costs can bring you way up there. And I believe the thread is about having a strong / reliable long block that would support the intended use.
If your budget is at least $10k for the long block , you should be able to build a stout long block with aftermarket internals that would support at least 800rwhp reliably for the intended use you mentioned.
With regards the Carrillos saying you don't want a lightweight rods ... generally , the lighter your whole rotating assembly the better. Lighter rods doesn't mean they will easily bend. I just wonder why you didn't want the Carillo rods being lighter ?
11-29-15, 09:21 AM
#12
Someone once told me that if you lighten everything up, (flywheel, rods and pistons, and pulleys,) then the engine won't have enough weight to keep turning on idle. Or it'll want to die because of lack of rotational mass.
They said the best thing to do is to balance it out for example, factory flywheel and pulleys with lightweight internals, or factory weight internals and lightweight pulleys and flywheel.
They said the best thing to do is to balance it out for example, factory flywheel and pulleys with lightweight internals, or factory weight internals and lightweight pulleys and flywheel.
11-29-15, 11:45 AM
#13
The lighter your whole rotating mass which include your rods , the better it is because there would be less weight to rotate .. less weight to move that means you can push it to higher RPMs... higher RPMs can get you more HP .
11-29-15, 03:37 PM
#15
Yeah, on the second page it shows that .045" squish is what's optimal.
If I use gte pistons and Ge head and head gasket,
piston to deck = .005"
Ge gasket = .010"
Ge head = .040"
That makes it lower compression and perfect squish.
So lightweight flywheel, pulleys, and rods and pistons won't hurt anything at all?
Even if that were the case I still wouldn't want aftermarket pistons for the fact that they slap when cold. And the whole potential cracking thing if they're silicone based, or whatever the statistic is, scares me.
If I use gte pistons and Ge head and head gasket,
piston to deck = .005"
Ge gasket = .010"
Ge head = .040"
That makes it lower compression and perfect squish.
So lightweight flywheel, pulleys, and rods and pistons won't hurt anything at all?
Even if that were the case I still wouldn't want aftermarket pistons for the fact that they slap when cold. And the whole potential cracking thing if they're silicone based, or whatever the statistic is, scares me.
Last edited by grumpi300; 11-29-15 at 05:13 PM.
