kdick91

Alrighty, another Aristo swap question. It is known that the Aristo has ceramic impeller shafts that like separating at about 1.6bar. Everyone in the Supra world says that 1.4bar is completely acceptable. As opposed to running a restrictor ring, I was wondering why no one runs another BOV when doing an intercooler. What would be the downside of this? Could I just throw in a BOV and not worry about over-boosting the stock twins? Does the BOV need to be recirculated??

Thanks!

cnewingham

iTrader: (3)

blowoff does not regulate boost. the wastegate does

kdick91

Well, it's gonna prevent pressure spike. I figured it might be possible to install one with a ~20psi spring and it'd start blowing of once boost got too high.

In case this is a bad idea, how else can you control boost on stock twins without the restriction plate? The car doesn't need to pass emissions, so it will be decatted.

cnewingham

iTrader: (3)

let me go into a little more detail.

BOV is used to relieve the pressure build up on the intake side to prevent surge and is not really needed on an automatic due to the way the auto shifts as compared to the manual trans. (unless running a built setup and a good amount of boost)

The wastegate is what actually regulates the amount off boost the turbos will boost before bleeding it off into the exhaust which is why a restrictor plate is used to keep from over boosting. If you are not going to run a boost a boost controller and only stock boost which will raise itself by going BPU then just install a BCC to keep from hitting fuel cut and you will be fine.

bov will not prevent boost spike

where in TX are you located at?

kdick91

Well I'm in college in CO right now. I may be working in PA or at home in Houston this summer. The car will be registered in a nearby county in CO (emissions exempt).

I plan to run a BCC and a SAFC but this is a very budgeted build and I don't plan on going single yet, so I figured I don't need a boost controller. Do you think running stock mufflers will be restrictive enough or is that too far downstream? I honestly want to be boosting to right around 20-22psi. Right at the end of the 'safe zone' for the turbos.

cnewingham

iTrader: (3)

if your on a budget then leave it at stock levels. you would not be able to hit 20 - 22 psi without a boost controller anyways. And if you arent planning on going single soon then I wouldnt up the boost to the limits or your be replacing them in short amount of time.

My car hits 15 - 16 psi running open dp and I have hardpipes and intercooler.

on another note, If you are going to use the SAFC to its potential and safely you need a wideband to tune it with which is another $200 - $300
Stock exhaust is fine as it is the same as the Aristo but too be honest with you about your goal and sound of your budget you going to broken down in a short amount of time.

"Maintence before mods"

kdick91

Well, that's why I am here learning haha. I have provisioned all the maintenance I need. I already have a wideband. It's an LM1. I really think I may just fly by the seat of my pants on the exhaust and how it influences boost. If I can get it mated up to the stock exhaust with cats and it boosts fine, I will be a-okay with that. If it is only boosting to stock levels though, I will start freeing up the exhaust to get the boost up to 16-18 (after re-reading it seems that is much safer). It just seems to easy to leave boost on the table like that.

Johnny D

Damn right

kdick91

Lol all of it?

Johnny D

Free up the breathing first bro. Intake, exhaust, downpipe, test pipe, hardpipes, intercooler and a bcc. Then go from there. U don't wanna **** up Ur turbos too early in the game

kdick91

I honestly just want the most powerful setup I can do reliably. I am no novice to the car building world. If something blows up, I can and will rebuild it. I'm just new to 2JZs. I have only been building N/A LS motors. I really want to just run, as previously stated, 16ish PSI until I finish up my last couple of years in college.

deknick

with my 3" open downpipe and first cat delete, BCC, greddy FMIC, pod filter, colder temp plugs, i only hit 15/16 PSI with the boost controller turned off. the effiency of the ceramic twins is 17 PSI, anything past that and nothing more happens but decreases the length of the turbo's.

had mine on a dyno with the boost controller hooked up wrong, and it made less HP at 20 PSI, than it did at 17 PSI.

don't take the stock twins past 18 PSI unless you have a spare turbo sitting around waiting to be installed.

and the stock recirc valve is more than enough for your goals, don't need a BOV, the only way to increase boost on your stock twins is to get a free flowing intake and exhaust, and if it flows to much, put in a restrictor ring, and even then, you won't want to run it like that, as the lag will be HORRID and the boost curve will be pathetic

kdick91

Awesome advice. Thanks so much for clearing things up. I'm hoping I can hit 16psi with all the emissions equipment still in. But if I can't, oh well. Life goes on haha.

EDIT: Second question though, if I am going to only run 16psi, do I NEED a boost controller?

Johnny D

Not really

deknick

if it helps, on JDM twins, with a short ram intake fitted, 3" downpipe and first cat delete to stock piping into the second cat, then to twin resonator delete to 2 straight through mufflers, and with my boost controller turned off, i can only hit 15(ish) PSI.

so for you to hit 16 PSI with stock 1st cat, downpipe, 2nd cat, both resonators and stock mufflers, might me a little hard without a boost controller