Fuel questions: detonation?

[fuforums]

I have a 2.5 intercooled with the mitsu turbo. Only mods are grainger valve and the intercooler. I just got this beast running from storage and it's awesome. Thing is, seems like there is a tinny sounding noise when I get on it pretty hard but not when just revving in neutral. My A/F meter shows green lites at WOT not even in the orange middle section but I'm wondering if that is detonation I hear or maybe an exhaust leak? My pipes are in bad shape and I haven't been under there but I don't want to blow anything up before I get a new exhaust system. With a stock system like this and only running 12psi surge leveling out to 10psi I shouldn't be having a fuel problem, right?

Joe
91 Shadow Turbo Intercooled 2.5

[WVRampage]

What do the plugs look like,but you shouldnt be at the limit yet.

[turbovanman²]

What octane gas? 10-12 psi is about max on 87 pump gas. Whats your base timing set at? you could also have sh*t gas still in the tank. What your hearing is detonation, you can still have enough fuel but you can still get it.

[bn880]

That does sound like detonation from the description. The only way I could see that happening is as mentioned, ---- gas, low octane OR, terrible heat soak and much advanced timing. (not likely)

[shadowdude]

What octane gas? 10-12 psi is about max on 87 pump gas. Whats your base timing set at? you could also have sh*t gas still in the tank. What your hearing is detonation, you can still have enough fuel but you can still get it.

ok so whats your opinion on the max boost for our crappy 91 octane here ??? with the big intercooler and all the good stuff of course .

[fuforums]

I have a bad head gasket so it could be because of that. Going to change it this week when it comes in.

[turbovanman²]

ok so whats your opinion on the max boost for our crappy 91 octane here ??? with the big intercooler and all the good stuff of course .

Probably 14 ish,

But Paul has been known to tune for bad gas, I think 8valves layed down over 300 whp and 300 ft/lbs on pump gas.

[shadowdude]

I really really really really would like to make 275 whp on 91 octane gas.Were or who ( Paul? )is the best to get a SBEC calibrated for this ?? I would obviously give them complete details on what i have for a set up.it has to be possible ,man i want it so bad i can taste it.

[Una]

I have a bad head gasket so it could be because of that. Going to change it this week when it comes in.

Or it could be the other way around.. Detonation usually causes blown head gaskets..

[turbovanman²]

I really really really really would like to make 275 whp on 91 octane gas.Were or who ( Paul? )is the best to get a SBEC calibrated for this ?? I would obviously give them complete details on what i have for a set up.it has to be possible ,man i want it so bad i can taste it.

Paul is the cal tuner for www.turbosunleashed.com Contact Chris and Paul is hard to get ahold of these days.

[shadowdude]

Oh BTW one more question,if I have a walbro 255lph pump,52pph injectors ,a 4 to 1 rising rate regulator and my static fuel pressure is 30psi and i am using 91octane and timing is @12* HOW CAN I STILL BE RUNNING LEAN at 18psi?? my EGT gauge goes right up to and past if i let it 1500 degrees in less than 30 seconds under WOT.I am getting really frustrated with this car.

[bn880]

It can if a regulator is not working properly. get a fuel pressure gauge installed and look at it when you boost.

[shadowdude]

All right ,i will do that today and post back A.S.A.P ,thanks .

[shadowdude]

Well ,I put the gauge on and went out and tried it and of course ,even though i am seeing 50psi at full boost 18 psi ,it still wants to climb right off the scale on the EGT.this is so not right!! I have everything the way it is supposed to be but for some stupid ,one in a billion reason it just wants to keep going lean.i am sooo close to just getting rid of this car ,i have never had such a hard time with a car as i have with this one.Three years of money speading and wrenching and i still cant win !!

[shadowdude]

ok so ,after calming down and using my head ,i now see that i figured wrong and 18psi of boost on my set up for fuel should see 72 psi of fuel pressure ,which i am not ,so i have a "stupid" question,can you hook up a RRR backwards? besides that what else ?? the adjustable is new,any more than 30psi static and it will be friggen hard to start. sigh why didn,t i take up knitting instead.

[contraption22]

2.5's with swirl heads are extremely sensitive to spark knock. Take a degree or 2 out of your total advance.

[shadowdude]

Yup ,i agree ,and I will be timing to 10*.Stock calls for12* of course.What i dont get still is why am i only seeing 50psi @WOT ??? I need 70psi ,well ...72psi to be exact.

[Una]

Weak fuel pump.. Runnin a Walbro 255 yet?

[shadowdude]

Yup ,running the walbro 255lph ,along with what I listed up above .This is why i am stumped as to why i am running low pressure at WOT.It just doesn,t make sense . who ever figures this one out it a master TD tech ,cause i dont get it thats for sure.

[bn880]

Well it's pretty obvious the RRR isn't working properly for you. I mean, you could first do a pump check by closing off the retun line for a second and checking if you get near 100psi of fuel pressure. It sounds like you are running only on your primary regulator @30psi + 18psi fuel pressure (due to boost gain).

YES it's possible to hook up a RRR backwards. (you have a primary AFPR and then a RRR right? Or is it an all in one with static adjust and a 4:1 gain?)

Basically if you have only one regulator and it is the RRR, it's not working as advertized, it's working as 1:1 gain.