:(

Well I finally tore apart my backyard turbo'd sebring.. cracked the side (both ringlands) of the #2 piston. I chaulk it up to an injector locking.. could have been a weak spot in the piston too, but all the other pistons are fine, indicating that they were receiving enough fuel.

Therefore.. for those who run stage II (greater than 6psi) and are still using stock injectors... you might wanna consider getting a set of 270-330cc injectors on your christmas list to yourself. Really i can't see how Hahn and Star can actually recommend running injectors with fuel pressures greater than 100psi. Sure it works.. but for how long is the question.

I'm replacing that piston and putting my 440's and AFC in so i can lower the WOT fuel pressures to a sane amount (50-60psi).. there's a reason why 1G's come with 450cc and 1:1 regulators stock..

ttyl

WheatKing

-- DSM Junkie --
4 - 1G talons
4 - Avenger/sebrings
1 - Jeep to tow em home when they break

Detonation can occur even with ample amounts of fuel. (Our ECU's can't seem to pull timing past 14* advance at WOT) Stock pistons are brittle and cannot withstand the uneven stress forces of detonation under any circumstances. It's common for even slight tuning mistakes to destroy these pistons, and the margin for error gets even smaller the greater the boost. I blew mine running 9PSI with 440's and a 3:1 regulator, always got low EGTs and fairly safe voltages. #2 piston cracked exactly like yours, the other three were 100%. Were you running an EGT gauge, Wheats? How much boost?

Also, i believe that the reason we can "safely" (big quotes there) run 100PSI fuel pressures is because our injectors will actually lock OPEN, dumping fuel, rather than lock shut.

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'95 Eclipse TurboGS (garage deco)
'95 TSi AWD (restoring a survivor)
'97 Talon ESi-T (poor impulse control)
'99 Eclipse RS-T (daily beater)
'13 Evo X (mostly stock)
'17 Sienna (Middle Aged Dad Mobile)



Factory Service Manuals: http://nawdu.de/files/

>Also, i believe that the reason we can "safely" (big quotes
>there) run 100PSI fuel pressures is because our injectors
>will actually lock OPEN, dumping fuel, rather than lock
>shut.

Yes thats the whole premises of being able to run the higher ranges of boost on stock injectors. You basically have a gross fuel dump with no pulsing of the injectors, otherwise you would be running lean. Kits with FMUs and stock injectors incorperate this inefficiency by design. Naturally its not precise but keeps you rich.

:farfrommugen:
Yes I still own a 2gnt.
Damn right I've been here longer than U
klassic_liven@yahoo.com

Humm .. learn something new every day.. lock open then eh?..

Unfortunately i don't have an EGT gauge right now.. was doing a lot of plug reading to gauge the fuel situation.. that and i'm running one of those wandering cartech FPRs.

I was pushing about 9-10psi.. just about finished a 300 mile trip, then an integra cut me off.. so i wanted a bit of revenge.. it bit me in the ass.. heheh next thing i know i have the wife on the radio (she was followin me in the jeep) tellin me i got smoke coming outta everywhere..

The cool part is the 14B spools at like 1700rpm.. hehe.. it's truely punch and gooooooooooo. bit flat on the top.. but a bit of porting will fix that.

I just got my AFC... dunno if i can convince the wife to get me an EGT gauge for christmas too..

Ahh.. the fun you have when your broke..

oh well.. i'm slappin a new piston in.. topping it up with 94 octane.. dumping some 104+ or toulene in and will be haulin ass some time in january..

If i find a job soon.. maybe i'll swap a 2.4L in while i got the motor tore down.. ya never know.

ttyl

WheatKing

-- DSM Junkie --
4 - 1G talons
4 - Avenger/sebrings
1 - Jeep to tow em home when they break

You're right there is a very good reason the 1st gens are using 450cc injectors

I had a similar discussion with some 4G63 turbo owners recently. The auto tranny 1st gens use 390 cc stock injectors and one friend is already datalogged at 137% duty cycle on them. We were trying to figure out how 235cc injectors can support 275 hp with 420A turbo kits.

We all guessed they run the fuel pressure super high (since the kits have fuel pumps), but we all agreed that isn't ideal. Yes, I guess if they do lock open that is OK, but injectors should really be run at about 85% duty cycle.

"Tutto fa brodo."

Todd Scungio
98 RS
15.173 @ 90.70 MPH

And also a 2011 Ralliart

Injectors are rated at flow@xxpsi of fuel pressure, normally 45psi. This is the flow of that injector at that specific fuel pressure only, just like peak hp would be that much hp at that specific rpm only. Raising or lowering the fuel pressure raises or lowers the flow rate accordingly, hence lowering the fuel pressure to make the injector a managable size for the ecu to allow it to idle. In the same instance, our stock injectors are 235cc, but only at 43.5psi, not at what we use it at on the turbo. Without doing the math again, running the stock injectors at 110psi which is required for 10psi on a S16G, makes the injector flow at something like 440cc if I recall correctly. The math takes 3 seconds I do not feel like spending here. The problem is that the injectors are being worked very hard to support this flow rate as the holes in them are only so large so to flow this much fuel it has to push hard and fast, which is where the effect of the injectors being locked open at wot would come from. The ideal maximum fuel pressure I hear recommended is 70psi, but this is not an absolute number, just like the 85% usage is a recommendation. They are more of good rules of thumb, but many cars tend to operate outside of these parameters, it depends on the situation.

I am going to stop now because I was going somewhere with this tangent and now that has completely slipped my mind. I know I had a reason when I started.

Cheers.

05 Mazda RX-8
06 Lotus Elise

chris u've been away from america a bit too long imo... come home!

im going to run 550s soon when i get my big 16G on

The Original 2GNT []D[][]Y[][]D


96 RS


97 GSX