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. :eyebrows:

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, :nod:

[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:confused: ) 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. :nod: 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, :p


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...:D

[Dave]

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

...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. :blah:

[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. :thumb:

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.

[turbovanman²]

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.


Yes, to a point. If you read at the intake, you are reading what the engine is taking in, correct. To get a true reading of what the turbo is cranking out, read at the comp outlet, I was shocked when I checked mine with my old IC, it would spike to 20 ish at part throttle and only read 5 ish at the intake. Also, turbo size dictates volume-lets say you have a TII and a hybrid 50 trim, at 15 psi, the hybrid will have more volume as the wheel can flow more. And as stated, colder air is denser-that equals more oxygen and with more fuel that equals more power. Thats also why if you install a larger IC and don't change anything, you will be leaner.

[Dave]

Yes, to a point. If you read at the intake, you are reading what the engine is taking in, correct. To get a true reading of what the turbo is cranking out, read at the comp outlet, I was shocked when I checked mine with my old IC, it would spike to 20 ish at part throttle and only read 5 ish at the intake. Also, turbo size dictates volume-lets say you have a TII and a hybrid 50 trim, at 15 psi, the hybrid will have more volume as the wheel can flow more. And as stated, colder air is denser-that equals more oxygen and with more fuel that equals more power. Thats also why if you install a larger IC and don't change anything, you will be leaner.

Thank you for our daily thermal physics lesson, captain. :cheer2:

[jckrieger]

I'm surprised nobody has noted this, but the stock cal is extremely rich at 15psi. Has anyone ever compared the 87 CSX cal and the Stage 2 side by side? The stage 2 has 2 degrees more timing advance and LESS fuel from about 13-15psi. This means there was too much fuel in the original cal.

As far as the stock injectors maxing out at 16psi, I'm not 100% that's the case either. The T3 motors made 224hp on the same injectors, and 16psi on a T2 will not make 224hp (on a stockish setup). Yes, the T3 is probably more efficient, but you can get quite a bit of fuel from the stock injectors (remember the guy who grounded the injectors with a pressure switch?).

As everyone said, in most cases it's not a good idea, especially if you're running a non-intercooled car or an intercooled car with a non-intercooled calibration. When it comes to the T2 cals, I believe there is plenty of fuel for a couple extra lbs of boost, as long as you're monitoring EGT's or A/F and you're not laying into the throttle for hours at a time.

Personally, I've run 16-17psi on my 91 Daytona Shelby (2.5L T2) with a modified stock cal and with a 3 bar cal and stock injectors. And no, it wasn't a 3 bar +40% cal :). If I were to recommend a setup like this, I would tell the person to get a 3 bar map sensor and socket their computer for one of Derek's awesome calibrations with the knock detection function. Total cost? Under $100 and the end result would be a very reliable, computer controlled fuel and spark system. That is if your voltage regulator doesn't burn up on your socketed SBEC :(

[iTurbo]

Just thought I'd add my two cents.

I dynoed my Shelby Lancer last year; made 196 WHP and 242 WTQ.

Mods:
3" exhaust (3" TU S/V, no cat, Ultraflo muffler)
MP 804 injectors
KN drop-in filter in '90 airbox
Walbro 255 ltr/hr fuel pump

I dynoed it at 14 psi, it was SOOOO rich at WOT it was off the scale. As soon as it spooled up the A/F went south and didn't reappear on the graph for the rest of the run.

Same thing happened with my brother's high mileage '89 TII Lebaron GTS. It made 178 WHP and ~220 WTQ.

Mods:
2.5" exhaust (2.5" S/V, no cat, Ultraflo muffler)
stock TII injectors
Walbro 255 ltr/hr fuel pump
14 psi boost

With the Walbro pump, I would say 16 psi shouldn't be a problem but personally I would want some WBO2 info before I tried it on a car I needed to rely on.

[Ground Rat]

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.
I've heard the opposite, advancing the timing will spool a turbo faster. Can you explain why retarding the timing would spool a turbo faster?

[jckrieger]

Retarded timing starts the burn process later, so the air fuel mixture does not complete burning by the time the exhaust valve opens. The mixture then continues to burn all the way through the turbine. This generates higher EGT's and gives less energy to the engine and more to the turbo. I might not be 100% correct, but this is basically how it works.

[Dave]

I should add I dont have anything monitoring A/F ratios. :D I'll be buying a Dawe's Device A/F gauge in the next 2 or 3 weeks.

I think why most people have detonated when pushing the limits of the stock injectors via boost is at part throttle. Most don't realize that our injector's pulse at only 25% flow at anythign OTHER than WOT. Of course at WOT they get 100% flow. It is possible to hit 15 or 16 psi at part throttle, I've done it, it's definately not safe. I think that's where I got my salt and pepper from. I'll try 16psi again.

But can anyone explain the redness on my porcelane? I don't run any fuel additives.

[iTurbo]

I'd try a different brand of gas and see if it goes away.

If I were you I'd start looking at getting a two-stage boost control if you plan to turn the boost up anymore. I have upgraded my Lancer with +20s/AFPR/adjustable zener and turned the boost up to as high as 21 psi and wasn't having problems (as far as I could tell) on 91 octane. It was only safe at WOT though. The problem is that the stock TII turbo spooled so fast it was impossible to modulate the boost level with throttle input. It made the car less driveable and kind of annoying to drive because the boost would go up too high at part throttle.


I've found that turning the boost up any higher than 14 was useless and actually slowed the car down because of wheelspin. The stock TII turbo hits so hard it's impossible to modulate the boost level with the throttle. I'm going to use a 2-stage boost controller setup with two grainger valves to get around this. I'm going to set the first stage at 10-12 psi so part throttle boost won't be too high and I'll still get decent traction in 1st and 2nd gears. The second stage will be activated via WOT micro switch so that high boost is only possible when you are flooring it in the higher gears.

[Lugert]

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

I ran 18 psi on my Turbo Van for 4 years. No ill effects.
All depends on how good the factory stuff is.

My fuel pressure was on the high side for a factory car, probably the reason why it worked.

Ran 14.87 in the van with wastegate unplugged, street tires. Drove 4 hours to the track and 4 hours home.

150,000+ miles on the van, the last 60,000 was either at 18 psi, or towing my Shadow.

[turbovanman²]

I ran 18 psi on my Turbo Van for 4 years. No ill effects.
All depends on how good the factory stuff is.



Exactly, so sometimes you win, sometimes you lose, :eyebrows:

[Dave]

Just thought I'd add my two cents.

I dynoed my Shelby Lancer last year; made 196 WHP and 242 WTQ.

Mods:
3" exhaust (3" TU S/V, no cat, Ultraflo muffler)
MP 804 injectors
KN drop-in filter in '90 airbox
Walbro 255 ltr/hr fuel pump

I dynoed it at 14 psi, it was SOOOO rich at WOT it was off the scale. As soon as it spooled up the A/F went south and didn't reappear on the graph for the rest of the run.



So is it safe to say that since I have no exhaust, 2 more pounds of boost, a TII front mounted intercooler, 3" ram air intake (sits directly behind grill next to the radiator), and a ported exhaust manifold that I'm making closer to around 230 to 240 WHP??

[turbovanman²]

So is it safe to say that since I have no exhaust, 2 more pounds of boost, a TII front mounted intercooler, 3" ram air intake (sits directly behind grill next to the radiator), and a ported exhaust manifold that I'm making closer to around 230 to 240 WHP??

Nope, my guess would be 215ish.

[jckrieger]

Nope, my guess would be 215ish.

That's around my guess too. I used to run 20-25ish psi on a similar hardware setup to Dave and made an estimated 250whp based on 101mph and a 3100lb race weight.

[Dave]

I wouldn't go by those kind of estimates, they usually are wrong. The ones for the ET calculators I mean.

[jckrieger]

That's why I based it on MPH and weight :)

[86Shelby]

2.5L, 16 psi, stock intercooler, ported exhaust manifold and 2.5" exhaust gave me 200.6 whp 294 ft/lbs. My LM and fuel system are different than yours but it's still a realistic estimate since you're running an auto, mine was a manual. I could see the additional power sap of the auto taking away the advantage of your better suited calibration.

[Dave]

2.5L, 16 psi, stock intercooler, ported exhaust manifold and 2.5" exhaust gave me 200.6 whp 294 ft/lbs. My LM and fuel system are different than yours but it's still a realistic estimate since you're running an auto, mine was a manual. I could see the additional power sap of the auto taking away the advantage of your better suited calibration.

I also have a stock but front mounted intercooler which noticably made it faster, a 255 pump, 3" RAM AIR intake, and no exhaust. So I think an extra 20WHP isn't too far fetched as the exhaust is the huge component here that helps.

Shoot I noticed that when we uncap ANY of our TM's at the track we've always gained 3/10. In formula that's 30WHP. Now I don't buy that, but I'm sure it's worth 15WHP.

Oh well, I'll be slapping her on the dyno when TU comes in May. Anyone know if I can make a pull? I don't have anything from TU, but I just want to make a pass or two.

[Bubba]

I also have a stock but front mounted intercooler which noticably made it faster, a 255 pump, 3" RAM AIR intake, and no exhaust. So I think an extra 20WHP isn't too far fetched as the exhaust is the huge component here that helps.

Shoot I noticed that when we uncap ANY of our TM's at the track we've always gained 3/10. In formula that's 30WHP. Now I don't buy that, but I'm sure it's worth 15WHP.

Oh well, I'll be slapping her on the dyno when TU comes in May. Anyone know if I can make a pull? I don't have anything from TU, but I just want to make a pass or two.

You have to buy a calibration to participate in this event. It's not too late though; I think there's 1 or 2 spots left.