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Discussion Starter #1
I've had my 1jz gte vvti (standard single turbo) for about 6 months, i have had it tuned using a ecumaster emu standalone and it is running 290whp - around 340 at the fly at 14psi. The engine is running great and the car is so fast and i am happy with it. But my tuner tells me even with bigger turbo the engine is max'd out and would require a thicker headgasket to start going any higher. I've been reading that 400-500hp should be easy without touching any part of the engine internally and people have gone higher. I have also searched for thicker head gasket mods but cant find much information that will help me, people have said dont touch the head unless you really have to and its broken!

Is my tuner correct? and a thicker head gasket is just what my engine needs? have other people used thicker gaskets to achieve 400+? or is there something up with my engine?

My next mod i was planning was going to be the tomei arms 8280 bolt on manifold, turbo, cams etc as seems easiest and i want to keep the factory look. i am looking at between 400-500hp comfortably.

The only mods i have at present is the ecu, larger intercooler and 3" straight through exhaust.
 

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Glad to be back
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It's probably time to find a new turner. The only limitations you're going to run into at those power levels are the turbo and injectors. IIRC, the stock VVTi single is good for 16-17psi I think? Then you'll have to consider swapping out injectors after you max them out. Since you're on a ECU, find some drop ins and retuning shouldn't be a big deal.

It what you're reading is correct, you don't need a thicker head gasket. there is no need.

Your future plans are a good plan for sure.
 

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JetFire
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Definitely sounds like you need a more knowledgeable tuner. Video below is of a stock longblock 1jzgte not that you need to make that much but you can make over 500HP comfortably with what you have internally. I had a single turbo 1jzgte stock longblock in my old SC300 made low 4's on pump gas on a T61 many years ago. I ended up going 2jzgte but the 1jz would have had no issues going into the 5XX range. This was way back before E85 became an option.

 

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Discussion Starter #4
Thanks guys, the tuner seemed to know his stuff... well he dazzled me with numbers and science but yea i was surprised he said that i would need to change head gasket before getting anymore. I mean the turbo is at 14psi at its lowest point, i cant make it go any lower even with waste gate jammed open. I did try increasing the boost to around 16psi but at full throttle it felt like i was hitting a fuel cut or hard knock. I've checked the setting and boost cut was set to 250Kpa (36psi) so i dont know whats up. Injectors at max on 14psi are at around 60%dc so i thought they would be fine for the extra boost.

Well this is the company http://www.tdi-plc.com/ they look at seem professional enough, they are local to me and had some f*ing nice cars being done.
 

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Unlimited Time Attack A70
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Your tuner has no idea what hes talking about. A 1j bottom end will handle 600+ easy untouched and has been upto 900hp on stock internals. Whats his reasoning for a thicker headgasket? to lower compression to boost more? its not an na-t swap... With proper fuel and a turbo and a way to manage it youll be well above your desired range and still not have to worry about the bottom end. The 1j-2j headgasket is a full multilayer metal gasket that has been proven to hold over 1000hp. Go find someone else that is well versed in the jz
 

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Question to suit.
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This video is suspicious, by the way. Not enough information. Other 1J folks have also questioned how authentic the power of the 1J in the video.
 

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Discussion Starter #8 (Edited)
Your tuner has no idea what hes talking about. A 1j bottom end will handle 600+ easy untouched and has been upto 900hp on stock internals. Whats his reasoning for a thicker headgasket? to lower compression to boost more? its not an na-t swap... With proper fuel and a turbo and a way to manage it youll be well above your desired range and still not have to worry about the bottom end. The 1j-2j headgasket is a full multilayer metal gasket that has been proven to hold over 1000hp. Go find someone else that is well versed in the jz
Its going back a bit but the tuner was saying something like to get more air and fuel into my engine i required a thicker gasket, There was no way to do it otherwise, he even suggested a bigger turbo and injectors would make no difference.

To be honest i am out of my depth, he baffled me with science and i couldn't really keep track of what he was on about.

The only thing i can think of is there was a problem with my engine, i did do a compression test, dry with a very old gauge that wasn't very specific reading around 160 which is on the lower end of the desired scale, but someone with 150's was running more mods with more power. So i cant say.

I will take it to another tuner, see what they can get out of it, will up the boost to 16psi or so im not to worried about the turbo shitting itself and i do have a set 850cc injectors that will fit if i modify the fuel rail.

This video is suspicious, by the way. Not enough information. Other 1J folks have also questioned how authentic the power of the 1J in the video.
All video's or dyno tunes can never be 100% confirmed, unless it was on your own car with an engine you know hasn't been modified, no one can say for sure that an engine hasn't been modified just from a video.

^ exactly. Tuner either has no idea what he's talking about or is thinking about another platform.
I keep thinking ive missed something, maybe he was trying to tell me something else but he mentioned head gasket change for sure.
 

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Unlimited Time Attack A70
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Its going back a bit but the tuner was saying something like to get more air and fuel into my engine i required a thicker gasket, There was no way to do it otherwise, he even suggested a bigger turbo and injectors would make no difference.

To be honest i am out of my depth, he baffled me with science and i couldn't really keep track of what he was on about.

The only thing i can think of is there was a problem with my engine, i did do a compression test, dry with a very old gauge that wasn't very specific reading around 160 which is on the lower end of the desired scale, but someone with 150's was running more mods with more power. So i cant say.

I will take it to another tuner, see what they can get out of it, will up the boost to 16psi or so im not to worried about the turbo shitting itself and i do have a set 850cc injectors that will fit if i modify the fuel rail.
all an engine needs to make more power is fuel, air and spark. so explain to me if you add more fuel and more air how you will NOT gain power. just adding a thicker gasket is going to make you LOSE power. you be making your combustion chamber larger, that will lower your static compression and create less response and less power with the same amount of fuel and air. This is basic engine fundamentals. I'm literally telling you hes wrong. That is just so ridiculous, i cannot believe this guy touches other peoples cars.... ok ill put it the way hes trying to explain it in very simple terms. Say you have 1 cup of fuel and 1 cup of air and you dump both of those into a 1 gallon bucket. now light it on fire. it goes boom. Now say you have 1 cup of fuel and 1 cup of air and this time you put it into a 5 gallon bucket. its also going to go boom but there is more space for it to go which creates LESS pressure. Also did you notice that i still only used 1 cup of fuel and 1 cup of air. The explosion is going to be the EXACT same due to the same amount of air fuel mixture. Hes trying to tell you that more air fuel mixture wont make more power...come on
 

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Find a new tuner...
 

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Discussion Starter #11
all an engine needs to make more power is fuel, air and spark. so explain to me if you add more fuel and more air how you will NOT gain power. just adding a thicker gasket is going to make you LOSE power. you be making your combustion chamber larger, that will lower your static compression and create less response and less power with the same amount of fuel and air. This is basic engine fundamentals. I'm literally telling you hes wrong. That is just so ridiculous, i cannot believe this guy touches other peoples cars.... ok ill put it the way hes trying to explain it in very simple terms. Say you have 1 cup of fuel and 1 cup of air and you dump both of those into a 1 gallon bucket. now light it on fire. it goes boom. Now say you have 1 cup of fuel and 1 cup of air and this time you put it into a 5 gallon bucket. its also going to go boom but there is more space for it to go which creates LESS pressure. Also did you notice that i still only used 1 cup of fuel and 1 cup of air. The explosion is going to be the EXACT same due to the same amount of air fuel mixture. Hes trying to tell you that more air fuel mixture wont make more power...come on
I think he was trying to say that the engine wouldn't take anymore air and fuel in physically. Like there was no way that more could be forced into the cylinder. On a na-turbo this would require a thicker head gasket and is exactly what i am doing on another nasp car. Either way the 1jz should be able to take more, maybe i missed somethign and he was saying my injectors couldn't put out anymore or something. but his final words where to change head gasket which i wont do.

Thanks for your help though, i will be taking the car to another tuner, i have larger injectors which i will swap over then i will max the standard turbo and see what i get. At some point when my wife isn't looking i will accidentally but the tomei stock looking setup or something similar.
 

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Unlimited Time Attack A70
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I think he was trying to say that the engine wouldn't take anymore air and fuel in physically. Like there was no way that more could be forced into the cylinder. On a na-turbo this would require a thicker head gasket and is exactly what i am doing on another nasp car. Either way the 1jz should be able to take more, maybe i missed somethign and he was saying my injectors couldn't put out anymore or something. but his final words where to change head gasket which i wont do.

Thanks for your help though, i will be taking the car to another tuner, i have larger injectors which i will swap over then i will max the standard turbo and see what i get. At some point when my wife isn't looking i will accidentally but the tomei stock looking setup or something similar.
i see, and yea hes incorrect. But looks like you have the right idea now. throw some bigger injectors in there see what your turbo can do, then upgrade as desired
 
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