Manual Boost Controller Question

[drifts14x]

Hey there, I am in the process of assembling my KA-T Turbo Kit, (3 pieces to go, 4 if I get the answer I'm looking for). Anyways, I am thinking about adding a Manual Boost Controller to my factory 1988 RX-7 Turbo, as it is wastegated at 6.7 psi. Ideally, I wanted to run 8-10 psi, to yeild about 250 Flywheel HP. So, if I install a boost controller like the one here:

http://cgi.ebay.com/ebaymotors...33742

Would I be able to increase my boost levels beyond 6.7 psi?

[IvanAtSPRacing]

I cant comment on that specific MBC, but a ball and spring style works quite well. We use a ball and spring style on the PhatKA-T.com R&D S13. Base spring pressure is 8 psi and we have run up to 16 psi.

The one thing you want to know is that the further away from base boost you go, the less control over the boost you have. 10psi is normally the max you would want to go beyond base to still have decent boost control (no spikes / creep)

[RMiller]

My brother uses a JoeP MBC on his FD and I use the same on my CA. Neither of us have spiking issues. He runs 10psi (on non-sequential), I run 1 bar.

[MarkEmark]

I had a JoeP MBC....sold it because it didn't work better than the $5 home depot setup I was using....actually it didn't work as well, if you could believe it...I have a pretty elaborate MBC setup though, it's not just a needle valve in-line with the wastegate...I also have a second bleeder line that puts air back into the turbo inlet...it's worked well and keeps the boost pretty constant...I could never justify spending $250 on an EBC-are they really THAT good? I doubt they're much better than a $5 MBC.

[andrave]

if you have spiking issues, they could be. Its also nice to be able to adjust boost from inside the cabin, if you want to have a setting for race gas, a setting for fast street, a setting for highway cruising, or whatever.

[RMiller]

Electronic is also better because it doesn't gradually open up the wastegate door, it stays shut until close to the boost setting. So it should reach full boost faster.

Some people have spiking issues with manual controllers, but I don't and my brother doesn't. My boost goes right to where I want and stays there, I'd say it is always within .05 bar throughout the powerband.

[Redline240]

I cant comment on that specific MBC, but a ball and spring style works quite well. We use a ball and spring style on the PhatKA-T.com R&D S13. Base spring pressure is 8 psi and we have run up to 16 psi.

The one thing you want to know is that the further away from base boost you go, the less control over the boost you have. 10psi is normally the max you would want to go beyond base to still have decent boost control (no spikes / creep)

Can't help but wonder why you used a mbc when the aem ems has a ebc...

Redline

[IvanAtSPRacing]

Can't help but wonder why you used a mbc when the aem ems has a ebc...

Redline

Thats an awesome question. I guess basically... I am lazy well... not really. For setting up the EMS on the twin's car, we used a Honda 1010 box and had to cut and crimp pins for every connection on the box. I wanted to keep things simple and not get into too much of the added features of the EMS without knowing that everything was working first. Slapping on a $60 MBC was quick and easy and would have cost just about as much as a GM boost control solenoid and wire harness. Now that we know everything is working well on the twin's car, we will be exploiting some of the extra features of the EMS. We are shooting for BIG power with the new semi built motor and will probably run the WG dual port now and use the boost control functions of the AEM EMS.

[AustinSilvia]

my friend got a $10.99 mbc on ebay and the spring came set at 10 psi as the lowest setting. he has no problems with it. it makes his turbo spool super fast (no creep), and he gets loads of power all the way through the rpm range (for a d16 del sol engine with bad compression it is fast... his clutch can't hold down the power). power comes very early too.anyway if you're going to get one check to find out what the lowest setting on the spring is, and purchase accordingly. my friend almost blew up his engine at first because he didn't know the spring rate and the thing boosted up to 15 psi in a heartbeat. how his engine didn't blow up is a mystery, and you probably won't be as lucky if you make the same mistake. anyway it runs fine and he has no problems with it at all now that it's set properly. rotaries are touchy engines though, and the computers are tuned for the turbo to spool in a certain fashion (not as fast as i am describing...). the guy i am talking about with the del sol also has an '93 rx7 twin turbo. his free flow exhaust alone makes the thing spool a lot faster and the stock ecu is not calibrated to handle fast spooling. anyway he has to be careful with it because it can run super lean in an instant because of the free spooling turbo and no fuel compensation. i'd say you will need to ensure your car is running rich before you turn up the boost with a mbc because that free spooling could blow your engine up. there could be a big difference between the newer and older rx7's though, so i'd say read about them and get as much info as you can before trying this.

[drifts14x]

I appreciate the input, you guys made my decision for me, I guess it's time to invest in an MBC to hold me over until the SARD Trigger gets cheaper.