Boost Beyond The Chip: Mbc Or Ebc

[USMC850T]

Ok so I've got the ST 17 psi chip, intake, and a full mandrel bent exhaust with straight through muffler / resonators. I'm looking to boost beyond the ST program of 17 psi, as I have heard it is mapped up to 21 psi. I am considering using the dawes multi-stage controller with a single boost controller. In doing so, I would be able to run stock boost level, and have a higher programmed level of X psi.

In doing so I understand that my boost levels will change with changes in atmospheric temp (density?). I also understand I run the risk of altering the design of my rods in the process .

Important questions:

1.) Is there any way to stop low level boost from occuring on the MBC setups, and how much risk am I actually putting on my motor of bending rods with the ST chip and 17+ psi?

2.) Would I be better off using an EBC system where I could adjust the max boost level relative to engine RPM, and ensure no excessive low RPM boost will be happening.

3.) Is there a way to set these MBC's up other than guess and check with the boost guage? IE setting and knowing exactly what PSI the BC will allow the turbo to reach before even installing it

Relevant info: 114K miles on car, overall good shape. 90% of driving is fuel economy oriented "grandma" driving, the remainder being drive like you stole it driving.

Thanks in advance

[prasamin]

you're out of the 15g efficiency range over 17psi. don't do it.

[the underlørd]

you're out of the 15g efficiency range over 17psi. don't do it.

thank you pras..

turbo efficiency... learn it.

[TorqueSteer]

If you boost above 17psi, your gonna spin tires down low, so it will feel like your alot faster, but since your above the turbo's and intercooler's efficiency range, your going to generate alot of heat that will cause a retardation of timing up top and your top end will most likely suffer as compared to 15 or 17psi. Id go with a MBC at 18..maybe 19 psi just to try it out, but most likely 17psi will be the best setting. As for setting the MBC out of the car to a boost level, you can do it with a pump and gauge, but it wont be what you see on the boost gauge when u run the car.....you have to take in account the intercooler loss, leaky hoses/vaccum lines/ leaky gaskets/ temperature and so on.

Oh and unless your using really crappy fuel and its incredibly hot out, I doubt a 15g has enough power to bend your rods.

[USMC850T]

73% is not that far out of "prime' 15G efficiency. Right now I believe I fall in the 75% range.

Currently assuming 100 degree intake temp & 17psi, turbo outlet temps should fall at 283 deg F.

At 100 degree intake and 20 psi, turbo outlet rises to 312 deg F.

Am i really going to incur a heavy penalty from the additional heat such that it negates any kind of power advantage from the extra boost?

Also can anyone confirm the ST chip has fuel and spark mapped to 21psi?

[USMC850T]

Edit: Ok so i definately don't have to worry about my rods on a 15G? Even at high boost levels?

[TorqueSteer]

26 psi on a 16t + a 100 shot of nitrous....and my rods still live to tell about it

I have the 15 pound version, Joseph had told me that its a beta test version that was used to create the final software for the T5 map. But even at 21 pounds shes been very much on the rich side and never got lean. Id go ahead and try it on the MBC, see if you like it in higher gears, if so roll with it.

I also just remembered that on the stock intercooler, it could be 16 or courld be 20 pounds, it didnt make too much of a difference. With the front mount, adding a pound or 2 really makes a difference, like a real turbo car should be lol. So keep in mind the efficient of the stock crap intercooler as well.

[S70 R]

do it!!! and learn how to feather the thottle!! :)

[maiku]

you can bend rods with a 15g if you have 21psi@2000rpm

go to the dyno before and after

see how much powah you run

[TorqueSteer]

you can bend rods with a 15g if you have 21psi@2000rpm

go to the dyno before and after

see how much powah you run

Is that possible though? Based on flow charts or anything, I truthfully don't look at the tach too much to even know at what RPM boost begins to build.

[maiku]

Is that possible though? Based on flow charts or anything, I truthfully don't look at the tach too much to even know at what RPM boost begins to build.

i don't know if it's possible....

but i do know that high boost at low rpm = bad engine sounds

i personally wouldn't run anything over 17 on a 15g

[Gioseppe]

what's nice about an ebc is that you can set the gain really slow, so it'll build the boost slowly, not spike to 17 instantaneaously like the 15g's CAN do at low rpm. don't have it hit the max psi you want to run till up higher, where there is less chance of bending rods.

[JCviggen]

what's nice about an ebc is that you can set the gain really slow, so it'll build the boost slowly, not spike to 17 instantaneaously like the 15g's CAN do at low rpm. don't have it hit the max psi you want to run till up higher, where there is less chance of bending rods.

Thats true. (i've got a Blitz DSBC on the 15G)

Incidentally, you can also gain top end power by building boost more slowly. You also get a boost limiter function which can be handy

[PorBleemo]

Out of curiosity what is the most efficient range for the 15G?

[Mesoam]

crappy tuning is what kills motors ;)