So my motor blew on the dyno today. Headgasket fromt he looks of it, not sure if there is any other damage. Had it tuned on a stock ls last year at 217hp at 8psi. This year with the brand new motor build, ala forged rods pistons rings oem headgasket etc. Anyways I went from dsm 450cc injectors to RC 550cc injectors. My tuner said last year the dsm inj. were at 64% duty cycle for my tune. Today the 550's were at 94% I believe he said. At onle 224hp!!! So was one of them justnot working correctly or what? I mean it blew coolant everywhere. The mechanic said smoke came out the exhaust first so thats why he assumed it was the headgasket as the problem. Anyone know if a f*cked up injector could cause this?

 

why did your tuner still tune it at 94% injector duty cycle ? 80% is pretty much max if u want the injecftors to be safe.

 

94% at 224whp? doubt it. . . unless there is like a tonnnn of timing and hes adding a tonn of fuel

 

your motor didn't blow. Your headgasket did. You may need to get your head looked over. Check for cracks, the coolant passages. but Im pretty sure you block is fine. You should have too much to worry about since the block is probably good. Second, do it yourself. From personal experience I would say your better off doing it yourself.

 

was this the same tuner that tuned your car last year?

 

i doubt if. if you only gained 7 hp , upped the injectors to 550 how are you running 94%

 

something doesnt seem right there. check to see what timing and fuel he was running

 

if I could get that info I would, however he decided to do one more pull when the injectors where near the maxed 94% just to see what was up. Not sure what the timing was though. And he did add more fuel I remember him telling me that. Also, he was the tuner who did my car last year so he had the logs from that still and was comparing.

 

What is the static fuel pressure at?

 

CHANGE TUNERS....bottom line.

 

94%???? on a 550 and 218 WHP? shouldnt you have been blowing out black smoke like 007?

 

fuel pressure was 43.
can't really change tuners, this guys does fabulous work.
and I have no idea what blowing out black smoke would mean if the injectors were at 94% duty cycle at 218hp... please explain more

 

94% duty on 550's is 197 pounds of fuel an hour. That's half a gallon a minute. Even at a pig rich 0.6 BSFC that is enough fuel to support 330 hp.

 

Post the dyno chart up with the air fuel graph.

 

I'm still thinking 1 of the 4 injectors just wasn't working at all, or very little. That would cause the other 3 to overwork am I correct?
I will see what I can do about the dyno graph.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by j-robsDA &raquo;</TD></TR><TR><TD CLASS="quote">I'm still thinking 1 of the 4 injectors just wasn't working at all, or very little. That would cause the other 3 to overwork am I correct?
I will see what I can do about the dyno graph.</TD></TR></TABLE>

no, every cylinder is seprate from the others, if ones not working that would cause one cylinder not to fire, maybe an increase in fuel pressure

 

43 psi is to low if you are boosted. Base pressure, its fine.

It should rise 1:1 with boost, or the pressure ratio across the injectors will be too low.

 

Who makes a 1:1 FPR? I am using RC550 cc with stock FPR and do not have problems.

 

Aeromotive... etc. All the regulators for fuel injection on summit/jegs are 1:1...

So is your factory FPR.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Flr Power &raquo;</TD></TR><TR><TD CLASS="quote">Who makes a 1:1 FPR? I am using RC550 cc with stock FPR and do not have problems.</TD></TR></TABLE>

a factory fpr is a 1:1 almost all of them are unless your talking fmu's