View Full Version : Jspec wastegate limit?
Stock turbos,no boost controller, how much boost will i be pushing?
3" exhaust no cats. I use 91 octane and dont want to pass 15psi
Thanks
You'll be hitting 1.6bar or more on j-spec turbos with no cats and a freeflowing exhaust.
You don't really want to run more than 1.2 if you can help it. Get a restrictor plate in the exhaust to get the boost back down to a sensible level before you commit turbocide.
You'll be hitting 1.6bar or more on j-spec turbos with no cats and a freeflowing exhaust.
You don't really want to run more than 1.2 if you can help it. A restrictor plate in the exhaust will get the boost back down to a sensible level before you commit turbocide.
Ouch even 1.2 is way too much for 91 octane dont you think?
Any way to lower the boost without exhaust ring?
You could put a brick under the accelerator?
You can run 1.2bar on V-Power or similar.
Have you got something against restrictor rings? You could knock a quick one up yourself from some sheet steel....
RobSheffield
12-08-07, 20:28
Chap is from USA....will they have Vpower? IIRC US octane is different.
Well if the ring is my only option i will have to do that or install one cat or something. 2.5" silencer on the muffler will do the job?
What is the deal with wastegate's? Spring is too stiff ?
Sorry for this dumb question, this is my first 2jz :)
The hole in the wastegate is too small and cannot bypass enough exhaust gas to slow the turbines down enough to limit boost from the compressor wheels.
The restrictor ring (or cats and stock exhaust) create enough restriction to limit exhaust flow through the turbine housings. Basically boost limit is not done only by the wastegate on the J spec turbos - the exhaust design compliments the wastegate function.
I wouldn't fit a cat (they create and trap far too much heat), I'd put a restrictor ring (shaped like a gasket with let's say a 1.875" hole in it) between your two decat pipes. You'll have to play with the hole size to get up to the boost you want - may end up a shade over 2" diameter
It's an easy mod for the safety factor you get on turbo life.
And yes - they had V Power in the states before we did!! :)
Ask away...don't worry about asking stupid questions but you will find a whole heap of info using the search function too.
Chap is from USA....will they have Vpower? IIRC US octane is different.
:yeahthat: It'll be a US spec Supra so same turbos as the UK-spec, so not problems with overboosting.
iaintslow to answer your original question, you'll be running stock boost of around 0.8bar.
Will it make any difference where the ring installed? After the second cat will do it? Or silencer tip on the N1 style muffler?
Will it make any difference where the ring installed? After the second cat will do it? Or silencer tip on the N1 style muffler?
Forget about the restrictor ring you don't need one. The guys were thinking you had a Japanese Supra, in which case you would need one, but on your US spec Supra you don't.
It'll be a US spec Supra so same turbos as the UK-spec, so not problems with overboosting.
Mine overboosted after replacing the stock exhaust with an HKS :(
Forget about the restrictor ring you don't need one. The guys were thinking you had a Japanese Supra, in which case you would need one, but on your US spec Supra you don't.
i do have Jspec one :)
i do have Jspec one :)
Oh right, you will need a restrictor ring then, it doesn't matter where it is placed, after second cat is fine.
Oh right, you will need a restrictor ring then, it doesn't matter where it is placed, after second cat is fine.
Cool :) you think muffler silencer will do the same job? Also can i run 1.2 on 91 octane Shell v-power or whatever? or should i limit it to 1 bar?
Cool :) you think muffler silencer will do the same job? Also can i run 1.2 on 91 octane Shell v-power or whatever? or should i limit it to 1 bar?
If it's a 3" after market muffler it won't be restrictive enough, I think you'll definitely need a restrictor ring fitting to limit boost.
Do you have a boost gauge fitted? If not get one ASAP so you know just how much boost you are making.
I'm not sure about the US fuel octane ratings, as you use a different measuring unit to the UK, I'll let someone else answer the other question for you.
Here we use RON (Research Octane Number).
In the USA they use RON+MON/2, called PON (Pump Octane Number), hence the lower numbers for their petrol. MON is Motor Octane Number.
So their 91 PON is our 95 RON.
To get the equivalent of our 98 RON V-Power you'll need 94 PON
Hope this helps! :)
Here we use RON (Research Octane Number).
In the USA they use RON+MON/2, called PON (Pump Octane Number), hence the lower numbers for their petrol. MON is Motor Octane Number.
So their 91 PON is our 95 RON.
To get the equivalent of our 98 RON V-Power you'll need 94 PON
Hope this helps! :)
So if you use 95 ron in your country how much boost can you run?
Thanks
So if you use 95 ron in your country how much boost can you run?
Thanks
We don't use 95 in TT's at all, they were mapped to run the 100ron petrol they have in Japan so even our 98 is a compromise.
I blew my engine on 98oct Ron and 1,2bar boost, 2 pistons melted down and the head has an opening between 5and 6 cyl.
I blew my engine on 98oct Ron and 1,2bar boost, 2 pistons melted down and the head has an opening between 5and 6 cyl.
I doubt thats down to your fuel though, hundreds of people here drive their cars at 1.2bar on 98 RON and have had no real problems (aside from the odd blown turbo). I'd suggest you had another issue with your fueling.
Edit - just realised you can't reply. Time to pay up ;)
I blew my engine on 98oct Ron and 1,2bar boost, 2 pistons melted down and the head has an opening between 5and 6 cyl. That's not the fault of the fuel though. That's like me saying that I had a puncture and got made redundant while I was running 98 Octane fuel.
98 RON at 1.2 bar is quite safe if the car is setup right.
- - - -
Edit
Homer beat me to it while I was reading the thread :(
Damn thats kind a suck, all i have here in California is 91 :( nothing i can do. Sounds like i will need EGT installed. Where do you guys usually install egt on stock TT ?
I have a newly installed Aristo 2JZ-GTE vvti in my IS300. Boost definitely creeps without any restriction.
Mine is in full TTC mode with secret sauce mods (EGCV delete, IACV delete/port, all VSV delete). I have a 3" downpipe and midpipe going to a 2.5" axle back perf exhaust.
Saw boost creep to 16psi at 4300 rpm. I expected this thanks to all the good info on these boards.
I have a metal catalytic converter now on order hoping to cure the boost creep and smell issue in one shot. I've always intended to do the cat but it will be earlier rather than later now that I have A/F mostly dialed in so I don't have to worry about burning up the cat.
http://www.teckkits.com/IS300/GTE/DSC_1186.jpg
I have a newly installed Aristo 2JZ-GTE vvti in my IS300. Boost definitely creeps without any restriction.
Mine is in full TTC mode with secret sauce mods (EGCV delete, IACV delete/port, all VSV delete). I have a 3" downpipe and midpipe going to a 2.5" axle back perf exhaust.
Saw boost creep to 16psi at 4300 rpm. I expected this thanks to all the good info on these boards.
I have a metal catalytic converter now on order hoping to cure the boost creep and smell issue in one shot. I've always intended to do the cat but it will be earlier rather than later now that I have A/F mostly dialed in so I don't have to worry about burning up the cat.
http://www.teckkits.com/IS300/GTE/DSC_1186.jpg
Nice swap :) i got jdm 2jzgte which going in to 1993 240sx. Before i start the car after its done i want to be sure i dont blow anything up. Trying to do research on boost level with this shitty 91 octane.
Damn thats kind a suck, all i have here in California is 91 :( nothing i can do. Sounds like i will need EGT installed. Where do you guys usually install egt on stock TT ?
You could run a water/alcohol injection system as well. This will allow you to boost a little higher whilst still keeping the engine nice and cool and det free. There are some problems with this - if you rely on it 100% then you can have issues if your tank runs dry or you get a blocked jet or something...
vBulletin® v3.7.3, Copyright ©2000-2008, Jelsoft Enterprises Ltd.