I have been under the impression due to much reading and due to personal experience on multiple dynos that 21psi is pretty much the standard for pump gas (in my case, 93oct). I was recently notified by Precision Dyno that not only is 21psi not the standard, but that 23psi is considered CONSERVATIVE on pump gas (no race gas, no toulene, no alcohol injection) based on this quote from Nick@Precision,

"Secondly, 23psi on the stock turbo is PERFECTLY CONSERVATIVE."

So, if 23psi is conservative, that would mean that 24-25psi is more standard on pump gas, right? I am only able to run 24-25psi on race gas without knock and with a healthy timing advance upwards of 23-24 degrees by 7500rpm in 4th. On the dyno and at the track, if I try to run a sustained boost level above 21psi on pump gas, I incur knock. The response from Nick@Precision was,

"In your case, you cannot boost over 21psi without knocking and I feel sorry about that, as it should not cause detonation with a proper tune."

Also,

"The other point is that if you are detonating with 23psi (on pump gas) then your tune needs to be "revised"...At 23 psi you may be detonating because of an overly aggressive timing map. NOT because the 93 octane fuel reached its threshold."

So, from this, I gather that it is not better to tune for an aggressive timing advance, but rather to keep the timing more conservative in order to run higher boost with lower octane? Correct me if I'm wrong. Does this make more power than keeping the boost lower while maintaining a solid AFR and an aggressive timing advance? Since I obviously don't have nearly as much experience as these guys and am only a novice tuner, I'd like to hear thoughts from other experienced tuners on these notions.

If possible, I'd also like to see some track results from someone running 23+ psi on 93oct (no alky, no fuel additives). Thanks...

 

Did you ask him these questions?.....This is gonna start a war of opinions!! If what Nick says is accurate,then he knows more than most. I think the bottom line will be; of course you can tune it for higher boost, but your margin of safety will be out the window. I think its a great debate.

 

I didn't want to do anymore whoring of the other thread, so I started my own. I hope there is no war; I just want the truth. If Nick is correct, then I will be changing my tuning philosophy, which means I will also be changing my advice to others. I'm very skeptical on 23psi being considered "conservative" for pump gas, so I'd like to have that verified.

 

I've read this as well. I'm not sure what to buy off on as far as this issue goes. I know with the upgraded actuator much higher boost levels are possible.

I also noted your MBC from your sig. I upgraded to the AVC-R. I know people complain about it all the time, but I noticed a definite improvement over the Hallman. I can now have my boost setup differently for each gear, RPM, or Injector Duty Cycle. When I set the thing to my second map and run a default 21psi across the board, it is a night and day difference. I know people don't generally like EBCs and I'm not trying to start a war.

 

That's fine and all, and I don't disagree, but I'm not referring to holding boost through a boost controller or eliminating taper with a stiffer WGA. I'm talking about the ability to run high boost on pump gas without knock. I'm also talking about the notion that 23psi can be considered CONSERVATIVE boost on pump gas, when I consider it very aggressive.

 

It really depends on what the tuner is using for an EMS. SAFC users may have a hard time on 91 oct, boosting 23psi, since it has no way of retarding timing. With full timing control, there should be no problem spiking to 23 psi that tapers off at high RPM's. I was running this way w/ my XEDE for over a year. Now that I have a bigger turbo, I can run 23psi to redline w/ the colder air.

 

I don't know if you'll be able to run higher boost without upgrading the WGA, but I do see what your saying. I can't get past 1.55 bar without severe taper on the stock turbo. I normally run 1.5 bar as my max and 1.3 to 1.4 in different RPM/load ranges.

I don't know how accurate the factory knock sensor is but I have 0-5 knock reading (according to my SAFC) at 1.4-1.5 bar in 4th gear WOT all the way to 8K on 93 octane.

 

i would think on the stock turbo running 21 psi and more timing would be better

but i am also pretty novice on the tooning, bump for a good question

 

Like I have said many times along with the rest of my staff, 23 psi is perfectly safe on pump gas (93 octane) as long as you are tuned properly. This is on the stock turbo and supporting mods.
Talon you can save what I just said and put it in your sig. It will never change.
There certainly will not be any war. You are fellow member looking for advise from many on this board that all share different theorys. It should be quite interesting the responses that will come from this thread.
Let the games begin!

 

Good points. I'm referring to a flash (not S-AFC, since I realize it is inferior), and I'm not talking about 23psi at redline, but more like a brief spike that settles to 22-23psi and holds through the meat of the powerband (4500-6500rpm). After that, the stock turbo will naturally taper, but during that middle section, I'm referring to a sustained 22-23psi being considered conservative. I sustain 20-21psi in 4th at the track and on the dyno with 93oct without knock, but no more than that.

 

I didn't say anything about it being safe. I know that it can be safe, but you said 23psi was conservative. We're talking about tuning and making power at higher boost levels on pump gas...levels that are usually used by people on alky or race gas. That's where my questions lie. Can 23psi be considered conservative? Feeding off of that, can 24-25psi then be considered normal and not conservative on pump gas? Can you make better power at 24-25psi on pump gas than at 21psi with more aggressive timing and AFRs?

 

I am no guru, but i know when we were tuning my car both on 94 and on alky, both of my maps are no where near your timing up top. I was surprised to see how removing the timing in the mid range and up top didn't hurt power and just cleaned up all the nock noise we logged. On 94 i run 23ish to redline and the logs are very clean as far as nock.

 

I don't see what the problem is. I am running 23-24 all day long on 94 pump gas in my car.
I know how Nick tunes this way but you have to understand it is not like he is going to come out and tell because then he is giving away tuning information that other tuners then can use to thier advantage.
The way this boost level becomes conservative is either using EcuTek flash or through AEM.
You are definitely not going to do it with an AFC.

 

I understand what you're saying. This is why I'm asking. Are these the only guys who are able to make 23-24psi work on pump gas, or is everyone able to do it? I haven't seen any track results of people claiming to run such high boost on pump gas, so it's hard to verify. I also haven't seen dyno numbers from such boost levels on pump gas that trump 21psi numbers on pump gas.

I'm looking for verification through many avenues...not necessarily for Precision to explain their secrets. Also, if this is considered conservative, then who is running a setup that is NOT consevative? There is a wide gap between conservative and aggressive, so who is in the middle? I'd like to see those dyno numbers and track times if they exist...assuming these people are running around 25psi on pump gas.

ManOfFaith, you bring up an interesting point. I am obviously getting my advanced timing on race gas due to the leaning out of the SAFC, which causes the ECU to provide more aggressive timing maps. I thought this was helping me to go much faster (trap 4.8mph higher than pump), but perhaps it is not providing as much additional power as it could due to extra "noise"? This is possible, but I'm not sure. I'd be amazed if I could trap even higher than 113.2 in 4th. Can you tell me your trap speeds, timing peak (degrees/rpm), and boost level on the alky map?

 

I can second that. My car essentially holds a flat 22psi to and past redline without any ill affects in consistency on 93 octane. This is not the first time I've heard of a professional in the field recommending higher boost over more agressive advance. Took me a little time to accept as well since we've all been programmed to that 21psi peak standard.