Let's get a vote from the vets here

what is the risk level associated with running 15 psi on a ported engine, upgraded IC (at least M2 med), free flowing exhaust (straight through style with baffles only) and all fuel upgrades with Power FC (PLENTY of fuel, high 10s to low 11s AFR)

I've been told anything above 14 psi and you are rolling the dice with 93 octane pump gas...opinions/experience?

 

Just get some AI if your worried.

 

Ive never heard that over 14PSI is not good on 93. As long as it is tuned right there shouldn't be a problem. 15 pounds is a lot for the stock turbos though.

 

I thought 15 or 16psi was the limit to 93 octane, but now gas stations all have ethanol in the gas. Which could lower the chances for detonation.

 

Are we talking Rx-7's specifically or all turbo cars?

 

news to me (that all gas now has ethanol)

 

Yeah, please back this up with some supporting data.

I have my low boost setting on 10 and high on 15 but not with twins. I have not had any problems so far.

 

You should look at the gas pump next time you fill up, all the gas stations I have been to. I have seen a sticker on the pump that states there is a percentage of ethanol in the gas(10%).

 

Maybe this is only in NJ, I don't know. Have you guys checked out Tom94RX7, he runs 19psi on stock twins and pump.

 

The stock twins won't last long at elevated boost levels, but it can be done. I ran about 16 psi for 2 years before I started seeing excessive shaft play. If you plan to do it for extended periods then go for an upgrade. There comes a point where you are just generating more heat than relevant power. The stock twins are really out of their efficiency range so I don't feel it is a good idea.

 

Thank you Rotary Experiment Seven, I was only stating that someone has ran more then 15psi on pump, Tom94RX7 for example

 

I have not seen this if Fl or GA. Maybe the south is just behind.

 

on 93 pump gas? full open exhaust?

 

I believe they instituted it about a year or so ago... all gas in the states is now 10% Ethanol. They did it to help it burn cleaner I believe. I know that Va is that way at least.. Though I was pretty sure I saw that it was a country wide thing (maybe the gas stations down south just neglected to put the stickers up..)

 

I run 15 to 16 but mix a few gallons of 100 in to up octane a bit. Like 4 gallons per fill up. No problems for 12000 miles. I have changed out a set of turbos at 7000. I am running a used set for $200 right now. They old set had 60k on them previously.

 

ok, then the question becomes, does this really equate to lower combustion temps and decreased risk of detonation or pre-ignition? has anyone measured it?

 

I ran my twins at 15 psi for about 15k miles (from 75k to 90k) until they blew.

There are a lot of variables involved......my attitude was, 'let's see how long the little bastards will last'

 

stock twins wont last long on 14+psi , i ran my 13b with 60-1 and 20psi on pump for months without problems , its all in the tunning

 

Was that your stock twins, or the BNRs?

 

You sure about that? What about this?

https://www.rx7club.com/showthread.p...ght=enrichment

 

heck if you have a good ignition, 93 octane, a excellent intercooler.. i dont see why you couldnt run safely 15psi on the twins for a while.. as long as you have a good tune.. Id like to try it.

 

actually I'm running BNR Stage 2s which should be a little more efficient than the stockers at 15 psi

 

what are the stage 2's like? do they have the 360 degree bearing same as the stage 3's?

 

nope, and Bryan doesn't make them anymore, but they spool faster than the Stage 3s

 

Stage 2s have upgraded compressor wheels. They spool faster than the 'new' stage 3s (brian's only current offering) because of the smaller stock turbine wheels, vs the larger beefier turbine wheels of the new 3s.