View Full Version : ST 185 Boost Controller

09-26-2011, 09:09 PM
I want to increase the boost on my stock ST185, it's from 1992 and I was wondering what kind of boost controller I should get and what kind of PSI is safe to run on that engine? I'm a total noob so any information you have would be helpful.


09-26-2011, 09:25 PM
Use a ball and spring type manual boost controller or an electronic boost controller.

The amount of boost pressure that is safe is all dependent on the health of your motor. Before you increase the boost you should give the motor a good tune up(plugs, wires, cap, rotor, fuel filter, air filter, oil change, coolant flush). With a healthy motor you can run 15-16psi safely on the CT26. The 92 ST185 fuel cuts at 17psi. If you plan to run 16psi all the time I would recommend ditching the top mount intercooler and get yourself a front mount. Keeping intake temps down at that kind of pressure will prevent detonation.

The Captain
09-26-2011, 09:25 PM
Have you done any supporting mods? I wouldn't try any increase until you do a downpipe and some kind of intake.

09-26-2011, 09:34 PM
This is a popular MBC.


I use an HKS electronic boost controller. It's nice being able to adjust boost pressure from the cabin.

09-26-2011, 11:24 PM
I was a huge believer in manual boost controllers, and ran them on both of my MR2s.... untill I went electronic, WOW, what a difference. Back in the day, I used a Blitz DSBC, but for my ST185, I will be using the EMS to control boost.

09-27-2011, 02:06 AM
Um yah I'm an ebc guy but I can't say nothing on this matter as how I have 2 boost controllers on my mr2. A manual one and a greddy ebc. But now soon imma be switching to an autronic sm4 and will be letting the sm4 control the boost.


09-27-2011, 07:21 AM
No need to do a downpipe. MBC + boost gauge is the best bang for buck performance upgrade on a gen2 3sgte. In fact I skipped getting a downpipe entirely since I knew I wanted a bigger turbo eventually, ran 15psi in my mr2 with just an intake and boost controller for a year. I don't know how well the stock TMIC's hold up to 15psi so I may change that along with the MBC.

I bought an EBC when I first got the car, sold it 4 years later for a ball and spring MBC and I haven't looked back since. If I ever go back to an EBC it'll be NLR's basic AMS-500

09-28-2011, 04:18 AM
I'm the opposite as sang. Intake and down pipe increased my boost beyond stock fuel cut without even running a controller. And EBC properly set up beats MBC any day of the week. I do however have my EBC being controlled by my stock knock/knock response system tho. I've got my solenoid grounded to the tpc pole so if the ecu would open stock tvsv my controller works. If criteria aren't met my controller don't work and I'm stuck around 11 psi.. I also have the simplest EBC evAr. the original Greddy ProfecB. 3 knobs and 2 buttons. (knobs are wastegate response, low boost level and high boost level. Buttons are power and low/high boost)

09-28-2011, 05:06 AM
I'd probably go with an Electronic boost controller but do they need a manual part? or do they run through the ECU?

09-28-2011, 04:17 PM
When installing any boost controller you have to block off the TVSV. It's really simple


EBC's operate independently. They consist of a control unit and a stepper motor. They are very easy to install. A 12v wire and a ground wire for the controller. The stepper motor has a few vacuum lines to install. One goes to the turbo, one to the wastegate, and one to an uninterrupted vacuum source on the intake manifold. Then you plug the harness from the controller into the stepping motor.

Here is a diagram of the installation of the HKS EVC EZ 2. This is what I have. Very simple setup. Most other systems are similar.



joe's gt
09-29-2011, 04:27 AM
Although I've never owned either, an EBC, while the greater up front cost, will keep the wastegate closed until the point of full boost and instaneously open it versus bleeding off boost through a wastegate that opens prematurely with a MBC.

09-29-2011, 02:53 PM
^Well Joe, a ballspring is supposed to do it that way too. You have to overcome the spring pressure for controller to allow boost past, but its not perfect.

09-30-2011, 09:19 AM
get a boost gauge first, stock fuel cut is ~14 psi on the regular 3SGTE IIRC. Make sure you're hitting stock levels ok before increasing anything, I was held back by a clogged cat.

09-30-2011, 10:20 AM
Check out these install sheets on two MBCs sold for the mr2 / trac. Might help you decide which way you want to go;



10-13-2011, 02:21 AM
On a gen 2 RC the fuel cut is at 17 psi like the gen 3!

10-13-2011, 06:50 AM
get a boost gauge first, stock fuel cut is ~14 psi on the regular 3SGTE IIRC. Make sure you're hitting stock levels ok before increasing anything, I was held back by a clogged cat.

Its actually ~12 psi at sea level. More the higher up you go. Here in Utah on a Rev1 Ill hit fuel cut around 14. Down at sea level I hit it at 12 on the dot every time.