dcchris311

Here we go..
I dyno'd my 94 Fd about a month ago with only downpipe and exhaust It still had a stock main cat and intercooler. It put down 237rwhp at 7psi. So here's my question. If stock boost is 10 psi and a all stock Fd puts down about 212rwhp, why is it that my fd is putting down 237rwhp at only 7psi?? Am i missing something???

ondabirdhouse

iTrader: (26)

There are a lot of factors but generally airflow is key. Anytime the stock intake and exhaust parts are changed out more free flowing performance parts you have increased airflow. From a less restrictive air filter to a larger better flowing cat back. Think of it as a straw...small taco bell straw at 10 psi only moves x CFM (cubic feet per minute). Now take a big 7/11 slurpee straw and flow the same x cfm and you get a lower psi because it's less restrictive better flowing.

Make sense?

0110-M-P

iTrader: (10)

Also, not all dyno's are created equal.

ondabirdhouse

iTrader: (26)

Very good point!

dcchris311

Yeah makes sense now, thanks guys!!

dcchris311

Here's another question without starting a new thread.
Have any of you guys ever looped your turbo so it only ran 7psi? The previous owner had this done by pettit racing.

ondabirdhouse

iTrader: (26)

What exactly do you mean by looped?
Modified waste gates/actuators?

dcchris311

I'm not exactly sure but I waiting for a call back from pettit racing.
When I googled it I saw another forum saying that he his turbos looped to only run 4psi during the break in process.

ondabirdhouse

iTrader: (26)

Now that I think of it its probably the solenoids that are somehow looped.
I'll look into this when I get home.

dcchris311

I found the thread that talks about ha king his turbos looped set at 4psi, but he doesn't really explain anything its the 6th post. .for sale 93 rx7 tt black/beige [Archive] - Tampa Racing

zack4173

iTrader: (3)

I've never hood of looped but if you are missing the little restrictors in the waste gate lines our cars will only run 7 psi.

ondabirdhouse

iTrader: (26)

That sounds like its it. I was thinking maybe the actuator rods were modified.

Sideo

Im sure he just took out the pills the "loop" is an empty line were the pill/ boost controller goes. pretty impressive that makes 237 at lower than stock boost even if the dyno was generous

dcchris311

Dude! I just got off the phone with Mazdatrix and I asked them whats the stock psi on a FD and they said 7-8psi!! WTF!!!! Why does everyone say something different?!?!?
[/QUOTE]Im sure he just took out the pills the "loop" is an empty line were the pill/ boost controller goes. pretty impressive that makes 237 at lower than stock boost even if the dyno was generous[/QUOTE] Would it make a difference if it was an awd dyno??

And yes the pills are missing and im confused on what the stock boost level is.....seems like everybody sees a different psi.

DaleClark

iTrader: (55)

From the factory, the FD does 10psi of boost, which drops to 8 before transition, then goes to 10 when the second turbo kicks in. This is the "10-8-10" boost pattern you'll hear people talk about.

The factory ECU controls the boost control solenoids to raise the stock boost to 10. If you disconnect or bypass those solenoids, you'll get 7 or 8 psi of boost. That's "spring pressure" on the wastegate. This is probably what they mean by "looped" - they bypassed the boost controllers. That's not a common term in the RX-7 community.

A bone stock FD is actually more like 220-225 to the ground. Your numbers are reasonable with your mods, you'll be making quite a bit more that that with better boost. But, the factory boost control can easily run away with the boost level with a downpipe and cat-back, if you can keep boost to 10psi you're good on the stock ECU, more than that and you're in trouble.

Also, according to your sig you have quite a bit more than the exhaust. Is that the same car you're talking about?

Dale

dcchris311

Why did Mazdatrix tell me that it was the right psi???? They also said that the pills don't really do much other than slow down the rush of the air coming into the wastegates.

Yes, its the same car but those other mods were added after the dyno run was done.

limepro

iTrader: (2)

When I bought my car it was also like this and the PO stated pettit had done it, it took a little bit for me to figure it out but very easy to fix.

Let me look at the diagram and see if I can remember which 2 hoses I need to attach, there was a single hose that was "looped" so it ran off wastegate only.

limepro

iTrader: (2)

Wow, looking at the diagram I don't remember which 2 but if you look in front of the UIM, take out the black plastic air box, the 4 metal "hoses" that are all attached together, there are 2 of them that are probably looped together, run those lines to the correct spots and it will boost correctly.

I think this was done to protect it from over boosting due to the more free flowing exhaust.

Edit: Unless you are missing the pills then you need to replace those.

dcchris311

You were right about those hoses and I'm missing the pills on the lines. After talking to Pettit, I deiced on keeping this way do to the fact that I won't run the risk of over boosting. I'm fine with 7-8psi, it's plenty fast for me haha
Thanks for the help fellas!! I greatly appreciate it!

Btw, im gonna go dyno it this friday with all the mods on it!!

Tem120

iTrader: (5)

what is this stage 2 ecu you speak of in your sig? if its one of those modified ecu they can usually run up to 14 psi . so you COULD add the pills back if thats the case . otherwise save up for a PFC and then put the pills back in . or one of those said modified ECUs