RX7Club.com - Mazda RX7 Forum

RX7Club.com - Mazda RX7 Forum (https://www.rx7club.com/)
-   3rd Generation Specific (1993-2002) (https://www.rx7club.com/3rd-generation-specific-1993-2002-16/)
-   -   will i be ok without boost controller (https://www.rx7club.com/3rd-generation-specific-1993-2002-16/will-i-ok-without-boost-controller-755587/)

Sideo May 12, 2008 05:00 PM

will i be ok without boost controller
 
if i am wrong, please correct me, im not trying to be cheap, its just that i dont have one yet. it seems that boost controllers only raise the stock boost level, but cant go any lower than stock, is that right? I am wondering if i will be ok without a boost controller for a few weeks with a ported wastegate, and the manifold modified to allow it to open more. the car isnt running yet but i want to make sure i will be ok for a little while.

4CN A1R May 12, 2008 05:07 PM

a boost controller on the lowest setting should generate 7-8psi on primary and secondary

parid May 12, 2008 06:12 PM

A boost controller won't let you run anything less than what the wastegate spring is. It's 8psi on the FD. Which is less than what the stock boost control is set to. So technically you could just run wastegate boost without any controller and it would be less than stock.

Assuming you haven't left out any other critical details, you shouldn't have any problems with the stock boost control and a ported wastegate. If anything, it should help you if you have boost creep issues.

RX7LINK May 12, 2008 06:22 PM

you have a PFC. its not the best to control boost but surprisingly it works quite well

Sideo May 14, 2008 10:56 AM


Originally Posted by RX7LINK (Post 8184331)
you have a PFC. its not the best to control boost but surprisingly it works quite well

i thought the pfc could not control boost unless you bought the boost attachment for it.

Mahjik May 14, 2008 11:26 AM


Originally Posted by Sideo (Post 8190016)
i thought the pfc could not control boost unless you bought the boost attachment for it.

I can, but it just uses the same mechanics the stock ECU uses so it's prone to the same issues.

Rotary Potato May 14, 2008 03:18 PM


Originally Posted by Sideo (Post 8184114)
if i am wrong, please correct me, im not trying to be cheap, its just that i dont have one yet. it seems that boost controllers only raise the stock boost level, but cant go any lower than stock, is that right? I am wondering if i will be ok without a boost controller for a few weeks with a ported wastegate, and the manifold modified to allow it to open more. the car isnt running yet but i want to make sure i will be ok for a little while.

Correct, a boost controller can only raise boost, not lower it. It keeps the wastegate flap held down longer so that you can raise your boost. It doesn't open it earlier or anything if you want lower boost. Porting your wastegate and installing a boost controller do two different things so your statement about "will I be ok for a few weeks....." doesn't make sense. If your car is more or less stock, you won't need to port the wastegate or get a boost controller. If you want to raise boost, get a boost controller. If you want to prevent boost creep, port your wastegate.

Mahjik May 14, 2008 04:51 PM


Originally Posted by Rotary Potato (Post 8190896)
Correct, a boost controller can only raise boost, not lower it.

That's not technically correct. A boost controller can lower boost, but it cannot lower it below what the wastegate spring allows. The stock wastegate spring allows about 7 PSI. So with an electronic boost controller, such as a Profec, installed, turning off the boost controller yields the lowest the wastegate allows which is lower than "stock" boost.

The cool thing is that something like the Profec has 2 boost settings (high & low). However, you effectively have 3:

Off - 7 PSI
Low - 10 PSI
High - 13 PSI

or whatever you set the low and high to....

Rotary Potato May 15, 2008 11:39 PM

Yes, you are correct..... as usual. I should have said not lower than the wastegate spring allows. I knew it in my head, but didn't get it into words, lol.

wolfman May 16, 2008 12:54 AM

If you want to keep the boost under control, I'd suggest the Greddy eManage. It's a piggy back onto the stock ECU and prevents boost creep.


Originally Posted by Sideo (Post 8184114)
if i am wrong, please correct me, im not trying to be cheap, its just that i dont have one yet. it seems that boost controllers only raise the stock boost level, but cant go any lower than stock, is that right? I am wondering if i will be ok without a boost controller for a few weeks with a ported wastegate, and the manifold modified to allow it to open more. the car isnt running yet but i want to make sure i will be ok for a little while.


Sideo May 16, 2008 02:42 AM


Originally Posted by Rotary Potato (Post 8190896)
will I be ok for a few weeks....." doesn't make sense. If your car is more or less stock, you won't need to port the wastegate or get a boost controller. If you want to raise boost, get a boost controller. If you want to prevent boost creep, port your wastegate.

my car is not stock. as it says in my signature i have full 3 inch exhaust, ported TB UIM LIM streetport, alot of flow mods. and like i said in my post i did port the wastegate. i just wanted to make sure it would not overboost without a boost controller, but it looks like i dont need one unless i want to raise the boost.

Smitter May 16, 2008 03:52 PM

i ran 14lbs on the stock twins with no boost controller, just the power fc and had no troubles.

dhays May 16, 2008 05:11 PM


Originally Posted by Sideo (Post 8196685)
my car is not stock. as it says in my signature i have full 3 inch exhaust, ported TB UIM LIM streetport, alot of flow mods. and like i said in my post i did port the wastegate. i just wanted to make sure it would not overboost without a boost controller, but it looks like i dont need one unless i want to raise the boost.

You really never mentioned why you are concerned about your boost levels and why only for a few weeks? It sounds to me as if what you want to avoid are boost spikes, correct? From my limited understanding, you could easily get boost spikes with your current mods. Are you waiting until you get a tune?

If it is boost spikes you are worried about, then just don't drive the car hard for a few weeks until whatever you are waiting for is taken care of. Or am I missing something here?

4CN A1R May 16, 2008 11:03 PM


Originally Posted by Mahjik (Post 8191216)

The cool thing is that something like the Profec has 2 boost settings (high & low). However, you effectively have 3:

Off - 7 PSI
Low - 10 PSI
High - 13 PSI

or whatever you set the low and high to....

i have the old school profec b and my boost stays at whatever i last set it at. with it on or off. the only difference i notice, is the gain. it pulls harder with the controller on

Smitter May 17, 2008 03:17 AM


Originally Posted by smitter113fd (Post 8198201)
i ran 14lbs on the stock twins with no boost controller, just the power fc and had no troubles.

i should have added that i did this with full exhaust, intake & large street ported motor


All times are GMT -5. The time now is 07:48 AM.


© 2026 MH Sub I, LLC dba Internet Brands