Max Psi on 57 trim

[supradoc]

Hey guys,

I was looking around the forum...but i still had a quick question.

I just put in a 57 trim CT and am getting it tuned soon. Just wondering approx where I could put my upper limit of psi. I'm aiming for the higher end of the safe range.

I've got 550/lexus afm, 3in piping, walbro, upgraded fmic and radiator, etc.

I wouldn't be running it regularly at max boost since it's still a daily driver, but I was looking to make the most of the car and the new turbo.

I was thinking around 18lbs...is this a realistic goal?

cheers

 

[jdub]

Has the HG been replaced?

 

[supradoc]

Has the HG been replaced?

Yup...with ARPs holding it down

 

[jdub]

On the Lex/550 combo, 18 psi is about max before you hit fuel cut. Depending on OAT it occurs between 16 to 18 psi. Take the tune slow and work your way up...watch carefully for knock (detonation).

Do you have a wideband O2?

 

[supradoc]

On the Lex/550 combo, 18 psi is about max before you hit fuel cut. Depending on OAT it occurs between 16 to 18 psi. Take the tune slow and work your way up...watch carefully for knock (detonation).

Do you have a wideband O2?

I don't...but I'm hoping the guys tuning my car do.
if 18 is about max...then i'd probably like to keep it slightly lower, for the simple fact that i like it when my car is running.
i'm not looking to break any records...just maximize the potential of the car...

 

[jdub]

That would be a good call
Might want to invest in a WB O2 in the near future. Do you have a AFPR and drilled the J tube out to handle the Walbro?

Another thing about the CT26 based turbos is the compressor housing is restrictive at higher boost. Much over 16 psi or so and all you're doing is blowing hot air.

 

[supradoc]

That would be a good call
Might want to invest in a WB O2 in the near future. Do you have a AFPR and drilled the J tube out to handle the Walbro?

Another thing about the CT26 based turbos is the compressor housing is restrictive at higher boost. Much over 16 psi or so and all you're doing is blowing hot air.

I never ended up getting an AFPR because the shop that was handling my car said that it wasn't actually necessary for my setup.

Looks like 16 is going to be my magic number.

This is pretty much the final step for my car...i've dumped way too much money into it...and now it's time to just enjoy the ride

 

[jdub]

What exactly are you going to tune with?

 

[supradoc]

What exactly are you going to tune with?

to be completely honest...i'm not too sure. i was given the name of a garage that tunes our cars.
all i know is that he's not going to use a dyno and that he'll be adjusting/tuning as i'm driving

 

[jdub]

I really hate to be the bearer of bad news, but unless you have a piggyback (like a SAFC) the ECU on the 7M is not able to be tuned. The piggyback has to remain wired to the ECU...it cannot be removed without the ECU going back to stock fuel maps.

If this is the same shop that told you an AFPR is not really needed, there's a huge warning sign going off right now. Just so you know, you are planning to double the boost psi the stock FPR was designed for. If you have fuel pressure fluctuations at 16 psi, it's not going to be good. Plus, an AFPR allows you to execute a global fuel pressure correction (usually down on the Lex/550) to make tuning with an SAFC easier.

 

[supradoc]

sorry...i should have mentioned that i have an safc neo. my car was previously tuned...and i'm just looking to get it re-tuned since i have the new turbo on...to avoid running lean on wot

 

[jdub]

LOL...a Neo will work. That's the answer I was looking for.

Keep in mind what I said about an AFPR

 

[supradoc]

thanks heaps jdub.

i'll keep the afpr in mind. i appreciate the advice.

cheers

 

[Koenigturbo]

I really hate to be the bearer of bad news, but unless you have a piggyback (like a SAFC) the ECU on the 7M is not able to be tuned. The piggyback has to remain wired to the ECU...it cannot be removed without the ECU going back to stock fuel maps.

If this is the same shop that told you an AFPR is not really needed, there's a huge warning sign going off right now. Just so you know, you are planning to double the boost psi the stock FPR was designed for. If you have fuel pressure fluctuations at 16 psi, it's not going to be good. Plus, an AFPR allows you to execute a global fuel pressure correction (usually down on the Lex/550) to make tuning with an SAFC easier.

For newbie audience: J Dub please explain "global fuel presure correction" and O.A.T. for me and hopefully other newber's on this forum. O.A.T.= Operating something temp?? "Usaully down on the lexus/550" please explain in newber language. Eye's not so smart as you is.....:cry:

I'm in the same "subway" Doc is in, also the exact goals and set up that Doc has. Except I have A.F.P.R. My original goal was 18 p.s.i., then I decided to play it safe at 16. You mean to say I can run up to 16 p.s.i. without a piggy back?? I bought this Greddy for nothing then? might as well install my piggy back, since I already have it. It will probaly run better any way with it.
Anything past 16 p.s.i. will need a piggy back...right?

Edit: "Oh" I get it, A.F.P.R. = stablizes the fuel presure, so the presure's not all over the place "hence" making it easier for the piggy back to tune.

 

[Supra87T]

O.A.T = Outside Ambient Temperature.

"Global fuel pressure correction" means you can adjust the fuel pressure. It is hard to tune the lex afm/550 combo without adjusting the fuel pressure.

 

[Koenigturbo]

O.A.T = Outside Ambient Temperature.

"Global fuel pressure correction" means you can adjust the fuel pressure. It is hard to tune the lex afm/550 combo without adjusting the fuel pressure.

cool, thanks!

 

[jdub]

"Global" - means you adjust across the entire ops range...on the Lex/550 the required FP is usually at the lower end of the TSRM ops range (23-30 psi) to keep you from running excessively rich at higher boost. You can adjust FP to where the Lex/550 combo will run fine with no piggyback (you'll still be rich at WOT)...I'm running 25 psi. An SFAC allows you to fine tune with smaller corrections required.

It's not that an AFPR stabilizes FP per say...it has an accurate, wider FP range capability that results in a predictable FP rise as boost increases. The end result is a more stable FP at higher boost when compared to the stock FPR.

The stock FPR is designed for a max of about 8-10 psi of boost to give a 1:1 rise in FP as boost increases. That means it's good up to a max of +10 psi FP over base FP. It will work, but there is no safety margin...max'ing out the stock FPR is like max'ing out duty cycle on the injectors (like running a Lex w/ 440's). It is not a good idea. An Aeromotive AFPR is good to 3-4 times the stock FPR...it has the FP rise capacity to handle almost anything we can throw at it on this motor.

 

[mkIIIman089]

The stock FPR is rendered useless once you put a Walbro in (at least the 255HP version). I tried 2, one brand new, and neither were able to bring FP low enough to be within TSRM range; and as soon as the fuel pump relay kicked over to 12v, fuel pressure would go to ~4.2 kg/cm^2 and just sit there.

So whether or not it'll take the increased boost level seems like it may be a moot point when it can't bypass even remotely enough to keep FP in check with just a Walbro 255HP installed.

 

[jdub]

^^^ Excellent point. I've never tested that, but suspected it might be the case. If you can't get base pressure in the TSRM range, it is a moot point.

 

[supradoc]

so at this point...if i have the walbro put in already...is there any advantage to having an AFPR installed...even tho my car is already tuned??