Quetions On The 1JZ Power

[ryangaudoin]

yea im currently with a pretty much stock 1jz and the only mod"s so far is
hks cold air intake
hks BOV
oil pressure,water pressure, boost guages
walbro fuel pump
as far i know that im trying to get this stock most out of my 1jz to it's full power before, if i feel like upgrading the turbo's, and intercooler which i might upgrade soon

1. I will be getting a full 3'' y-pipe and 3''downpipe,and the whole cat back with a high flo cat im thinking 3'' or 3 & half inch and a HKS EVC boost controller. So I want to now know if anyone know's for sure or is more acurate on this, how much power now will i be getting now from these Mod's and with the ones i already got??

2. and i will be getting a greddy fuel cut defencer & HKS Speed Limit Defencer later on with 550cc injectors, and a fuel pressure regulator,cam gears with the O2 wideband

now i would like to know if #2 would be good upgrade with the stock twins on the 1j and how much power i would probably get

Thanks Ryan

 

[ryangaudoin]

Before i go to #2 is it good to stay with all of the mods that i have and that i will get in #1 ??

- right now im really looking into keeping the stock twins and getting around 320 RWHP or more would this be possible?? and if there is something else for me to get 320 RWHP or more without upgraded the turbo's then you can tell me, as i would like to know ??

 

[ryangaudoin]

i also found out that for the 1j i wouldnt't have any problems with the fuel cut, unless i think if i break around the 125mph limit

but i heard i will need a speed cut limiter

 

[Boost Lee]

Any particular reason you're aiming specifically for "320RWHP"?

I only ask because I'm under the impression that you want to remain having this car in "Daily driver/Street car" mode.
If so, With a Fuel cut defencer and really anything beyond 1.0 bar on a BPU setup,
The stock twins are infamously known for failure beyond this point before too long.

The number of failing twins are astronomical when pushed to their limits, so don't get slap-happy with a Fuel Cut Defencer. In my honest opinion, I wouldn't run one...

With your common 1JZ upgrades....12-14PSI seems to net most around the 300-320RWHP marker; So this is certainly doable................but understand that just because it's a "JDM" motor with "JDM" twins doesn't mean they're brand new.
Some Japanese punk probably beat on these twins at some earlier point in life.

Your "#2" question...Well.
These are modifications that aren't really big Horsepower "adders" after install....
More or less, are made to *allow* you to go beyond those limits. (AKA Supporting mods)
(ie. 550cc injectors = ability to push more fuel, AFPR = compensate/add fuel pressure where needed, o2 WB = Safely monitor your motors air/fuel mixture, Speed-Limit Defencer = won't cut the car off at 12X.00 MPH.)

Jeff

 

[BlackMKIII]

With a full 3" exhaust, if I take the silencer out I bang on fuel cut all damn day, even with the boost controller off. It's a farking pain in the arse. I installed a fuel cut defender and had it "tuned" for about 1.3 bar.

Well about 6 months later I melted the pistons. Never even heard it detonate. Even though my wideband showed a nice healthy mixture, the cylinders were too hot and I got to spend more money on another 1JZ.

The moral of the story? FCDs ARE BAD, MMMMMKKKAAAAAAAAYYYYYYY????

 

[ryangaudoin]

so your saying that if i stay with the stock twins i can only get 12-14 psi to be on the safe side, and with the all the mods i have and that i will get in #1, i'll only get around 300-320rwhp if that's what your saying then for now that's fine with me. If i upgrade to steel turbines i would get more power ?

and for the speed cut limiter for the 1j i dont need a fuel cut defencer, the speed cut will do both is that what your saying or should i get both ????

i want to keep it as safe as possible for now till i upgrade to bigger twins, i dont want to go single with this supra i only plan for around 400hp in the future , cause i have a 180 im building to 500+rwhp = bigg money with mods,

and then a mk4 supra

thanks for me helping out
Ryan

 

[aphxero]

Dude you dont need to buy all that crap.

my bros daily driver makes 316whp with 3" dp/exh, FCD and a front mount that's it. Naturally hits about 14 psi. He's already put like 20k miles with no probs so far.

Also if you want to go over speed limit just cut the sp1 wire or put it on a switch. yeah it will throw a cel but so what. As soon as the ecu turns off it'll go away.

Btw, here's my bros chart:

 

[foreverpsycotic]

BTW, might want to look into an AFC and some 440cc injectors anywhere over 14psi. I had bad wastegates, and with a 3" dp and exhaust was seing 16psi at the intake manifold. The car didn't like that too much, and I ended up keeping 3gal of vp c10 in the tank with the rest @ 93 octane too keep it safe.

 

[10secdream]

Anyone find that the difference between running the 1JZ on stock twins at 14psi and say 18psi is very minimal?

 

[foreverpsycotic]

I felt a good bump from 12 to 16psi, but I never went over that.

 

[10secdream]

Ya I have a feeling that by running increased boost and thus lower timing really did nothing for me performance wise. Plus the stock twins are completely out of their efficiency range at that level.

 

[Gritz]

Ya I have a feeling that by running increased boost and thus lower timing really did nothing for me performance wise. Plus the stock twins are completely out of their efficiency range at that level.

Do you have anything to back up this statement, or is this hearsay??
Im willing to bet with a nice IC the stock twins would be pretty efficiency at 18-20psi...and make 400whp...If they will stay together:aigo:

 

[ryangaudoin]

if i can only get 300-320rwhp on stock turbo's before, or if i go steel turbines, and before i go upgraded turbo's, can i run this power all day if i want and i want to know for sure if i need a fuel cut defencer

aphxero are you sure it's 316 RWHP or to the crank, and how much would it help if i upgrade to steel turbines

 

[foreverpsycotic]

Do you have anything to back up this statement, or is this hearsay??
Im willing to bet with a nice IC the stock twins would be pretty efficiency at 18-20psi...and make 400whp...If they will stay together:aigo:

IIRC the highest stock twin whp was 412, and was done at 21psi. They blew up shortly thereafter.

 

[ryangaudoin]

ok so it looks like i'll only get 300-320 on stock turbo's which is fine with me, but i want to know if i run this power all day if i want, and i want to know for sure if i need a fuel cut defencer or not.

if i go steel turbines how much would that help, thats before i go upgraded turbo's

 

[Gritz]

ok so it looks like i'll only get 300-320 on stock turbo's which is fine with me, but i want to know if i run this power all day if i want, and i want to know for sure if i need a fuel cut defencer or not.

if i go steel turbines how much would that help, thats before i go upgraded turbo's

Sure that will help, but it might not be worth the cost, when you can just go single and be done with it..From the info i got low 300hp is fairly safe with the twins..don't for get these turbos are 15+ years old!! Do some more research on going steel and the cost..

 

[Gritz]

IIRC the highest stock twin whp was 412, and was done at 21psi. They blew up shortly thereafter.

Wow, do you know what mods it took to get there? cause around 400hp is all i would want in my 260z...The only reason i went single is because of cost and reliability...Do you have the dyno chart for this? i would imagine that 1j made a pretty nice tq curve with the stock twins...
If only it was cost effective to fully rebuild balance and add steel wheel turbines i would have prolly stayed with the twins...

 

[foreverpsycotic]

Wow, do you know what mods it took to get there? cause around 400hp is all i would want in my 260z...The only reason i went single is because of cost and reliability...Do you have the dyno chart for this? i would imagine that 1j made a pretty nice tq curve with the stock twins...
If only it was cost effective to fully rebuild balance and add steel wheel turbines i would have prolly stayed with the twins...

AEM, some sort of ignition box, cams, cam gears, tuning, 3" ypipe back and 1 hell of a tuner.

 

[Gritz]

AEM, some sort of ignition box, cams, cam gears, tuning, 3" ypipe back and 1 hell of a tuner.

Cool, are there any twins, that are a natural upgrade to the stock ones? New i might add..

 

[10secdream]

A Custom Twin Turbo kit would be the way to go. Then again why not just go single and have a more reliable and cheaper solution.