Thoughts on some infamous danger

[Dave]

I know what the majority of people will say if I ask to run 16psi on stock fuel. But I've done it... been doing it on pump gas for the past half year actually.

But I want some opinions as to why everybody thought this was dangerous? My plugs are usually a little whitish, never any salt and pepper. Always look good. I'm using 94 octane and running 12* timing, I have a TII mounted as a front mount and a stock T03 Garrett.

Thoughts?

[Bubba]

Stock fuel meaning pressure or octane?

[Dave]

Stock fuel meaning pressure or octane?

Both.

Stock regulator, filter, pump, injectors. hehe I now have a 255 pump, but that just got put in a few months ago. I definately will be swapping out filters to ensure good fuel flow.

Off topic - Christian did you get it running yet???? Mine will be on Monday, I had to swap trannies in the Acclaim yesterday, instead.

[Bubba]

I'd atleast put in an adjustable fuel pressure regulator and bump the base fuel up a couple psi just to be safe. A little less power is better than blowing someting up in my book. How do you think I ran 24-25 psi on an internally stock 2.5 motor? Having extra fuel of course.

Nope, still just as we left it. I gotta do some work today at a co-worker's house, but plan on hitting the garage tomorrow to try and finish things up. I just hope the head gasket doesn't leak this time, otherwise there's another problem, i.e. warped or cracked head/block. I seriously doubt it's gonna leak since the only time I had problems was under boost.

[GLHSKEN]

Safety. Why chance a good running block. You can do it yourself, but NEVER recommend something to someone that is risky.

[turbovanman²]

The stock injectors are maxed out at 16 psi, so any change in fuel needs and you have a lump of metal,

[Ondonti]

plugs dont sound good to me IMO


If you arent getting a little brown tinge then you are hurting something or else what you think is 16 psi is just due to your crappy boost gauge.

[89DaytonaTII]

or else what you think is 16 psi is just due to your crappy boost gauge.

that's what I was thinking, it's easy for a guage to be off.

[Dave]

I just got a brand new gauge, it even sits nicely at 0. I'm running 15.5psi now with 12* timing and 94 octane... pulled the plugs after they fouled out. Had a reaaaaal bad miss. Anyways the porcelain was all red (which doesn't make sense as I'm not running a fuel additive ) and on 2 of the plugs the porcelain had salt and pepper with the dark red.

So now I'm left to decide to either turn the boost down a pound or back the base timing back 1*. Ideas??

[Dave]

Oh and I gapped the plugs to 35. I thought it was too high, causing the electrode to jump, but it would create a longer electrode making the spark disperse more... is that right??

[GLHSKEN]

Dave, that should be fine for that boost level. The higher we go in boost, the more we gap them. I was running .028. a 400whp car I know was running .025. A 500whp car was gappes at .022

[turbovanman²]

Dave, that should be fine for that boost level. The higher we go in boost, the more we gap them. I was running .028. a 400whp car I know was running .025. A 500whp car was gappes at .022

You typed it backwards, higher boost, LESS GAP,


Also, larger gap, better spark which equals better fuel economy but with a boost engine, it means the spark can get blown out. So play around.

If you want to run stock injectors, get an AFPR and turn up the base pressure a bit.

[SpoolinGLH]

I think ken in the middle of his sentence started thinking of ring gap instead of spark plug gap...

[Dave]

I think ken in the middle of his sentence started thinking of ring gap instead of spark plug gap...

...or boobs.

Anyways so I think I did foul out a plug or two because I cleaned them up with a wire wheel on my bench grinder and today it was missing again. Time for new ones.

Simon, that will be my next mod after all these expenses are paid for... $472 later.

[ludwig340]

I did it, too, in my '89 Daytona Shelby (and loved it), but like Ken said, I wouldn't recommend it as safe because I got away with it. I had a very healthy low-mile short block and really didn't beat on it much.

I'm quite sure I could have destroyed it quite easily. Pretty sure the scanner just barely saw knock retard at WOT and we bumped the boost down slightly at one point.

[3Bar_Mopar]

One thing I've wondered.

Running that much boost on stock fuel on a stock T1 cal and an intercooler would cause problems, right? It seems to me that the T1 cal would not be set up with a fuel curve that could support the additional oxygen that the intercooler provides and you'd run lean....or leaner....is this right?

The T2 cars have bigger injectors becuase of the intercooler. The 2.5 have them because added displacement...but adding an intercooler ALSO to the 2.5 would cause a lean condition...

[Dave]

Adding an intercooler just cools the air down and compresses it together a little. It adds no more oxygen, it's the same amount. Just after the intercooler it's denser and much, much cooler.

I've began questioning my fuel needs to run 16psi and have the boost turned down now to 14.5 to 15psi. I will raise the boost to 16psi ONLY if I have two gallons or more or 110octane or higher. I'm considering pulling 1* of timing out to set me back to 11* base. Thoughts on this???

Also I took the plugs out, again, they still looked quite red (BTW I clean them everytime I pull them) and only one this time had salt and pepper on the porcelain. So I gapped them to .031 and I was running about 14psi but it felt even faster than 15psi with .035 gap. The gap makes a huge difference! I nailed 2nd gear so hard that the front end kicked out to the side on me.

I do hope to see high 13's on it with 16psi, race gas, slicks, no exhaust, and no interior.

[3Bar_Mopar]

Adding an intercooler just cools the air down and compresses it together a little. It adds no more oxygen, it's the same amount. Just after the intercooler it's denser and much, much cooler.

Densinty = more air crammed into the same space, which means more oxygen at the same boost level than without an intercooler, hence more power...

Also I took the plugs out, again, they still looked quite red

Mine were like this also...I never run any additives. Must be what's in the fuel from the refinery.

[Ondonti]

I would drop the boost 1 psi.

retarding the spark wont make up for a lean condition like you think it would. Retarding the spark also kills power.

Less boost and more timing should give almost the same power and better economy + peace of mind. Retarded timing will spool the turbo faster and give the "feeling" of being faster because of the increase in lowend torque but it will kill power.

[Dave]

I would drop the boost 1 psi.

retarding the spark wont make up for a lean condition like you think it would. Retarding the spark also kills power.

Less boost and more timing should give almost the same power and better economy + peace of mind. Retarded timing will spool the turbo faster and give the "feeling" of being faster because of the increase in lowend torque but it will kill power.

Hmmm interesting... makes sense.

Moving on... about the intercooler, the turbo is always spinning at let's say 15psi, it will always crank that much out AT THE TURBO unless the manifold pressure tells it that there's a restriction that makes it neccassary to run more than 15psi at the turbo to achieve 15psi at the manifold. So if there's a 2psi drop in the intercooler, the turbo will crank 17psi to create 15psi intake pressure. With that said, the turbo will produce this much air, or the same amount of air before the intercooler, just it will be denser. There wont be more volume, just a denser charge.

Atleast that's the way I'm seeing it... I'm still brushing up on my thermal physics. Gotta love turbo technology.