10psi with no mods?

[87witmoreboost]

My car is 100% original/stock and being one of such few, I want to leave it that way (as far as people can see). I want to get a MBC and run around 10psi, but won't do it if I need to do too much to safely do it. I would really like to leave the car completely stock other than the MBC (and a temporary t-fitting on a vaccum line to get the MBC to hold 10psi). I would consider an open air filter (eliminating the stock box), but do not want to touch my stock exhaust. Is the stock bypass valve safe at 10psi? (can the diaphragm handle it??). My car has 92.5k miles and it runs as good as new. My head bolts were re-torqued at one point to 70+ ft*lb , so I am not too concerned about the HG.

I love the car as-is, but would really like it to pull just a little harder. Anyone running a similar setup to what I want?

 

[swaq]

I wouldn't recommend running 10 psi without any other mods. Also, an aftermarket intake isn't going to gain you much. If you want it to pull harder you should start with a downpipe. Your exhaust will still look stock but you'll have more power and the turbo should spool quicker.

 

[OneJoeZee]

Turning up the boost a few psi with a stock exhaust seems pointless to me.

 

[tissimo]

I had a bosch bov on my car when I ran 10 psi with stock intake and exhaust..

Fwiw, Bone stock I ran 15.1 @ 91 mph and with 10 psi (fell to 7 by redline, used shims, mbc might be better) stock exhaust and intake I went 14.33 @ 95 mph.. Gained 4mph... a good 20-30 or so hp..

also just putting a full Turbo back exhaust same 10 psi I went 13.9 @ 100.. another 5mph gain.. another 20-30hp just from the exhaust

 

[emiliorescigno]

Don't bother if you're leaving the exhaust stock. It's like trying to breathe through a straw. Even if you work really hard to breath fast, you won't get very far, and you'll wear yourself out in the process.

 

[Dan88t]

FWIW, back in the day (when I was young and poor) I added a K&N FIPK and an MBC to my otherwise stock Supra and set it to around 11psi and the "seat of the pants" gain was certainly noticable. When I gutted the cats that gain was pretty noticable too.

But I was young and stupid and thought it was pretty cool how the turbo and mainifold would glow after a long hard run - then I'd just shut the car off.. I really didnt treat the car well...

 

[spinningheadboy]

I'm getting 8-9 psi, with just a k&N filter, cooleze 3'' downpipe, 3'' exhaust, lower turbo hardpipe. I have no boost controler.

Free up your exhaust, it makes a huge differance. I think the stock exhaust was meant to choke the 7mgte down.

You can have a near stock sounding 3'' exhaust when it's done right, if that's what you are concerned with.

cwd

 

[Poodles]

the stock intake isn't as restrictive as people think...

the exhaust on the other hand is a huge restriction (especially the elbow)

running 10PSI on a stock car won't hurt it IMHO, but you won't see the same kind of gains as someone with more mods...

 

[MK3.0dudeman]

I wouldn't recommend running 10 psi without any other mods. Also, an aftermarket intake isn't going to gain you much. If you want it to pull harder you should start with a downpipe. Your exhaust will still look stock but you'll have more power and the turbo should spool quicker.

dose any body run a aftermarket dp with a stock exhaust?I would like to do this for a lil bit how much more power would you make and also how dose it sound

 

[vas85]

Exhaust would have to be the most restrictive....

On a dyno my GT Limited with 10psi only drpped to 9.6 (with an MBC, 3'' Turbo back exhaust, K&N Filter, FCD, Highflowed CT26) where as my cousins R31 GTS-X which is a RB20DET with 13psi boost would fall down to something ridiculous like 8psi by the end? (completely stock car other than the MBC)

Point being said the car obviously can't get rid of the exhaust gasses quick enough to allow for more boost which is why it would drop so much I believe hence the reason why the stock exhaust is restrictive once boost is increased.

Invest in a full exhaust 3'' turbo back or so... and then with an MBC set it @ 10psi.

 

[starscream5000]

At least replace this one thing, I swear it looks stock with the turbo heat sheild on: Suprasport turbo elbow. Better than a MBC on a stock supra any day.

 

[7MsuprO]

I wont say anything about exhaust since everyone else has but unless you want looks stick with the stock filter. I believe it is a better "filter" than cone types and doesn't really lose you power on a stock setup.

 

[rumptis]

I did just what you are wanting to do, open air filter and MBC at first.

The stock exhaust if very restrictive like everyone says but upping the boost made a big difference down low but up top it would still fall on its face.

I dynoed mine like that and the boost would spike at 14 psi and then fall off to about 7. I had 237 HP and 290 ft/lb It would really give you a kick in your pants.

I say go for it but if you want any real increase in power then going 3 inch is the way to go. I now have 3" and just dynoed again at 10 PSI and made 269 HP and 280 something ft/lb.

Don't let all these nay sayers get you down. Once you feel more boost you will want more power and be changing your mind about keeping it stock.

Good Luck!

 

[87witmoreboost]

I have a lot to consider here - Thanks for the feedback everyone. I know I continue to hear that the exhaust is very restrictive, but I cringe at the thought of changing it. I really don't want the exhaust to be loud and do not want a huge muffler hanging out. I have a friend with a full 3" exhaust with a high-flow cat and apexi muffler and the car is far louder than I would like.

It sounds like everyone agrees that the Toyota air box is fine for the moment, which really makes sense. After all, if it was REALLY restrictive, it would mean that it would have to be so restrictive that that the vacuum it creates on the intake of the turbo is enough to slow the rate it pulls air in.

As for the exhaust, would an aftermarket downpipe mount to the stock exhaust? Would that help move exhaust gases enough to allow no drop in boost at high RPM's or is it the stock cat, resonator, and muffler? I think everyone sees my issue here - I love being able to drive down the highway and not hear my exhaust moan in my ear - i've been there with other cars and its simply annoying. Any more feedback is greatly appreciated!

 

[spinningheadboy]

An aftermarket downpipe will bolt to your stock second cat. There are quiet exhaust systems on the market. Mine as pictured below is a 3'' stainless cat back with a resonator. It may scare small children, but my exhaust is very resonable to live with. My wife drives the car to work occasionally, and says it sounds perfect.

cwd

 

[Poodles]

There are quite a few exhausts on the market that will flow better, and not be too loud.

Apexi isn't quiet by any stretch of the word LOL

Seriously, don't be scared to do these mods since it will show the LARGEST gain possible. You really can't go too big on a turbo, and freeing it up will make it a hell of lot more happy.

I run a DDP on a modified stock exhaust, and it hits very hard and pulls great. The stock CT will fall on it's face at higher RPMs regardless, but better exhuast helps a lot.

I wouldn't say that an intake kit is a waste of cash, it will show gains, but the stock airbox isn't really as bad as people think. It sucks in cool air and flows fairly well (could flow better with some help). I had to go to an aftermarket filter with my hardpipes (which is a nice gain as well, much more responsive).

As soon as you start modding, it won't stop, trust me, it's like crack. You get more boost, and then it's not enough, so you go after more...and more...

 

[rumptis]

that just cracks me up...LOL

It may scare small children

cwd

 

[themadhatter]

what you could do is get a 3" downpipe and install a cut-out before the second cat

 

[starscream5000]

As for the exhaust, would an aftermarket downpipe mount to the stock exhaust? Would that help move exhaust gases enough to allow no drop in boost at high RPM's or is it the stock cat, resonator, and muffler? I think everyone sees my issue here - I love being able to drive down the highway and not hear my exhaust moan in my ear - i've been there with other cars and its simply annoying. Any more feedback is greatly appreciated!

Yes, an aftermarket down pipe will bolt onto the stock cat, if you are getting one, make sure you either get a full 3" DP that will bolt onto the turbo elbow, or a full 3" DP with an integrated elbow. The two piece DP setup will look pretty much stock with the heat sheilds on it. Check out www.suprasport.com for the full flowing turbo elbow. Watch out if you are wanting a 3" DP and go shopping for it on ebay. Most of those shrink down to 2.5" after the flex section. They are fine in their own respect, but they will not free up the exhaust resrictions as well as a full 3" will.

If you leave the rest of the exhaust stock, it will be a tad more loud, will a bunch more response as far as spool time and a little extra boost to boot.

You can get aftermarket exhaust that are really quiet just as everyone is telling you. The HKS dragger is damn big, 3.3" with a resonator on it. I swear, I've stood beside a Supra with a Dragger and didn't even know it was running until the throttle was blipped.

 

[swaq]

There are some exhausts that have a more stock look and aren't as loud. I have the HKS Turbo Sport Exhaust on mine and it really isn't very loud and you wouldn't know it wasn't stock if you didn't know Supras.