the srt-10 trucks with the sts kits at 7 psi is just insane.....but i hear that they suffer oil issues with those trucks.....i forgot what the issue was but i know it had to do with oil

 

please enlighten me. with an aftermarket super/turbo charger, the boost for the crossfire will be minimal.

what i seem to read is 4-5 psi is about the limit for the compression ratio.

are the ecu's/fuel management system so delicate that it won't recognize a boost of 24-30%? [based on 1 psi=6%] and compensate with more fuel?

does anyone really know what the ecu is set to handle as it relates to 'leaning out'.

i realize my thoughts are a bit confusing, but everything i've read online about boosting any engine leads me to think the ecu could compensate for the additional air pressure/density.

please feel free to shred my thoughts

 

it will not compensate ... the system cannot compensate for such a large difference and you will lean out badly. to maintain a safe AFR at boost you need to be in the 12:1 range minimally. these engines are tuned to run leaner than that at WOT from factory. adding boost will mean it needs to compensate for the extra cfm and run richer than it is programmed to in order for it to be safe ... it is just not happening.

two options ...

one, disable the stock fuel pressure regulator at the tank side and use a adjustable rising rate regulator with a return line plumbed into the lower filler neck..

two, extra injector running off the schrader port of the fuel rails.

either way ... you need to provide more fuel.

5psi will give this car 50hp extra minimally ... that hp comes at the price of heat, the air charge will be heated as it is compressed, even the best intercooler cannot bring it down to ambient.. which menas you need the extra fuel and/or reduced timing to compensate ... i honestly think you can get away with just having extra fuel so long as your air fuel ratio tuning is done to perfection. the higher timing gives you a smaller window of error but does not necessarily mean it cannot be done safely.

 

5 psi will net a little more than just 50hp....If you wanted to make your non srt a nice sleeper you could always run a meth kit and higher octane...you could see 8-10 psi with those add ons with a mild street/dyno tune.

 

what are the injector sizes on the crossfire?

 

do a search I remember HDDP posted the specs, the stock injectors from what I remember, just barely supports 215hp

 

one, disable the stock fuel pressure regulator at the tank side and use a adjustable rising rate regulator with a return line plumbed into the lower filler neck..

either way ... you need to provide more fuel.
i honestly think you can get away with just having extra fuel so long as your air fuel ratio tuning is done to perfection.

ok...adjustable fuel pressure regulators will raise fuel pressure 1 PSI for every PSI of boost when connected to a source of manifold pressure.

using the formula: sqrt((boost+14.7)/14.7) * CR = ECR

sqrt = square root
boost = psi of boost
CR = static compression ratio of the motor
ECR = effective compression ratio
with boost being 5psi,
sqrt[5 + 14.7]/14.7*10.5=12.155245

if 12.1 is the safe max compression ratio for alumn heads and pump gas, then 5 psi is the optimum pressure.

so, if 5 psi increase of fuel is optimal,does anyone think the ecu can't keep up?

 

The fact of the matter is that they are bosch fuel injectors, and it will not be hard to find a higher flowing fuel injector. Thus the PCM sees so much fuel initally, but be able to run more boost in the end as far as fuel is concerned. there is no need to go into the tank to work on the FPR. Fuel is rarely a serious issue until over 15lbs of boost. There are minimal mods to take care of that. If you run more than 5 psi, you need to start looking at compression ratios, head strength, and bottom end strength.

on a side note there are 2 srt-6 engines on ebay for 1500!!

*EDIT*...I may ramble at times, but what I was saying is that the stock PCM can handle it.

*EDIT*...Information below is straight from tech connect, our (chrysler's) manuals

 

N/A
SPECIFICATIONS - ENGINE
ENGINE SPECIFICATIONS DESCRIPTION SPECIFICATION
GENERAL SPECIFICATIONS
Engine Type 90 ° Bank Angle Liquid Cooled with Dual Tuned Intake Manifold and Twin Ignition
Displacement 3.2 L (195.2 cu. in.)
Bore 89.9 mm (3.54 in.)
Stroke 84 mm (3.31 in.)
Valve System SOHC 2 Intake and 1 Exhaust Valve per Cylinder Roller Rocker Arms
Compression Ratio 10.0:1
Brake Horsepower 215 (160 KW) @ 5700 rpm (67.2 bhp/liter)
Torque 230 lb. ft. (312 N·m) @ 3000 rpm
Firing Order 1-4-3-6-2-5
Lubrication Pressure Feed – Full Flow Filtration
Cooling System Reverse Flow – Forced Circulation
Cylinder Block Cast Aluminum Alloy with Siltec Bore Liners
Crankshaft Forged Steel
Connecting Rods Forged Steel
Pistons Aluminum Alloy – Flat Topped
Compression Pressure 689 kPa (100 psi)
Max. Variation Between Cylinders 172 kPa (25 psi)
CYLINDER BLOCK
Cylinder Bore Diameter
Standard 89.900 – 89.915 mm (3.539 – 3.540 in.)
Repair Max. 90.150 – 90.165 mm (3.549 – 3.550 in.)
Out of Round 0.014 mm (.0005 in.)
Taper 0.03 mm (.0011 in.)
PISTONS
Piston Diameter 89.87 – 89.90 mm (3.538 –3.539 in.)
Piston Ring Groove Depth No. 1 3.1 mm (0.122 in.)
Piston Ring Groove Depth No. 2 3.1 mm (0.122 in.)
Piston Ring Groove Depth No. 3 3.5 mm (0.137 in.)
PISTON RING GAP
Compression Ring No. 1 0.20 – 0.35 mm (0.007 – 0.013 in.)
Compression Ring No. 2 0.20 – 0.40 mm (0.007 – 0.015 in.)
PISTON RING WIDTH
Compression Rings 1.5 mm (0.059 in.)
Oil Ring (Steel Rails) 3.5 mm (0.137 in.)
CONNECTING RODS
Bearing Clearance 0.026 – 0.054 mm (0.001 – 0.002 in.)
CRANKSHAFT
Main Bearing Clearance
Radial 0.030 – 0.052 mm (0.001 – 0.002 in.)
Axial 0.100 – 0.266 mm (0.003 – 0.010 in.)
CYLINDER HEAD VALVE SEAT
Valve Seat Width
Intake 31.000 – 31.016 mm (1.220 – 1.221 in.)
Exhaust 35.000 – 35.016 mm (1.378 – 1.379 in.)
VALVES
Face Angle 45° ± 1.5°
Stem Diameter
Intake 6.975 mm (0.274 in.)
Exhaust 6.974 mm (0.274 in.)
Head Diameter
Intake 36 ± 0.4 mm (1.417 in.)
Exhaust 41 ± 0.1 mm (1.614 in.)
Length
Intake 119.4 ± 0.2 mm (4.700 in.)
Exhaust 122.2 ± 0.2 mm (4.811 in.)
Valve Margin
Intake 1.2 mm (0.047 in.)
Exhaust 1.6 mm (0.062 in.)

 

SRT-6
SPECIFICATIONS - ENGINE (SRT)
ENGINE SPECIFICATIONS DESCRIPTION SPECIFICATION
GENERAL SPECIFICATIONS
Engine Type SOHC 18-Valve 90° Supercharged V-6
Displacement 3.2 L (195.2 cu. in.)
Bore 89.9 mm (3.54 in.)
Stroke 84 mm (3.31 in.)
Valve System SOHC 2 Intake and 1 Exhaust Valve per Cylinder Roller Rocker Arms
Compression Ratio 9.0:1
Brake Horsepower 330 (246 KW) @ 6100 rpm (103.13 bhp/liter)
Torque 310 lb. ft. (420 N·m) @ 3500 rpm
Firing Order 1-4-3-6-2-5
Lubrication Pressure Feed - Full Flow Filtration
Cooling System Reverse Flow - Forced Circulation
Cylinder Block Cast Aluminum Alloy with Siltec Bore Liners
Crankshaft Forged Steel
Connecting Rods Forged Steel
Pistons Aluminum Alloy - Flat Topped
Compression Pressure 689 kPa (100 psi)
Max. Variation Between Cylinders 172 kPa (25 psi)
Supercharger Helical Two Rotor Design
CYLINDER BLOCK
Cylinder Bore Diameter
Standard 89.900 – 89.915 mm (3.539 – 3.540 in.)
Repair Max. 90.150 – 90.165 mm (3.549 – 3.550 in.)
Out of Round 0.014 mm (.0005 in.)
Taper 0.03 mm (.0011 in.)
PISTONS
Piston Diameter 89.87 – 89.90 mm (3.538 –3.539 in.)
Piston Ring Groove Depth No. 1 3.1 mm (0.122 in.)
Piston Ring Groove Depth No. 2 3.1 mm (0.122 in.)
Piston Ring Groove Depth No. 3 3.5 mm (0.137 in.)
PISTON RING GAP
Compression Ring No. 1 0.20 – 0.35 mm (0.007 – 0.013 in.)
Compression Ring No. 2 0.20 – 0.40 mm (0.007 – 0.015 in.)
PISTON RING WIDTH
Compression Rings 1.5 mm (0.059 in.)
Oil Ring (Steel Rails) 3.5 mm (0.137 in.)
CONNECTING RODS
Bearing Clearance 0.026 – 0.054 mm (0.001 – 0.002 in.)
CRANKSHAFT
Main Bearing Clearance
Radial 0.030 – 0.052 mm (0.001 – 0.002 in.)
Axial 0.100 – 0.266 mm (0.003 – 0.010 in.)
CYLINDER HEAD VALVE SEAT
Valve Seat Width
Intake 31.000 – 31.016 mm (1.220 – 1.221 in.)
Exhaust 35.000 – 35.016 mm (1.378 – 1.379 in.)
VALVES
Face Angle 45° ± 15'
Stem Diameter
Intake 6.975 mm (0.274 in.)
Exhaust 6.974 mm (0.274 in.)
Head Diameter
Intake 36 ± 0.4 mm (1.417 in.)
Exhaust 41 ± 0.1 mm (1.614 in.)
Length
Intake 119.4 ± 0.2 mm (4.700 in.)
Exhaust 122.2 ± 0.2 mm (4.811 in.)
Valve Margin
Intake 1.2 mm (0.047 in.)
Exhaust 1.6 mm (0.062 in.)

 

a true rising rate regulator has a adjustable fuel slope so the ratio can be changed from 1:1 all the way up to 14:1 ... such as a BEGi MR2035

a 1:1 regulator is only useful if you are running massive boost pressures that are effectively counteracting your fuel pressures reducing the injectors spray volume and are using another module that allows you to tune the injector pulsewidth. this makes the 1:1 regulator maintain the injector spray volume at lets say 2ms at 0 psi intake manifold pressure the same as at 20 psi intake manifold pressure. without the 1:1 volume sprayed would be reduced greatly at 20psi as the fuel pressure would be effectively counter acted by that amount.

adjustable rate, rising rate regulator has never been my way to go about things as i prefer the accuracy of the auxillary injector but it will work

 

I just checked, they get the lower compression ratio, from the pistons.

Heads are the same part#
Pistons and connecting rods are different

 

An aux fuel injector is anything but accurate, unless you are running wide band O2, with an O2 on each cylinder. The fuel doesn't distribute evenly, you'll end up burning up at least one cylinder, also it completely mind F's the MAF, and PCM.

 

you mean to say the NA andSRT6 have the same cranks?

 

MAF could care less so long as you are not spraying the fuel over it damaging it over time. it does not affect CFM it sees.

stock ECU will be happy so long as the aux injectore is tuned to follow boost properly ... which will maintain the AFR the stock ECU expects at part throttle and the richer 12:1 ratio at full boost which the stock ECU will not affect as the stock narrowband o2 sensor is only accurate at 14.7:1 so the stock ECU does not look for lambda correction at WOT.


auxillary injectors so long as chosen carefully for their spray pattern and used with high enough a fuel pressure do a decent job of equally distributing the mixture to each cylinder unless the intake manifold is of crap design ... such as on the turbo 2.5 dodge motors we used to run many moons ago that had a uneven air distribution resulting in the spark plugs showing different temps across the cylindesr (this is how to check your system is running correctly, spark plug reading, EGT or wideband o2 per cylinder is the easy expensive way to do so). So a single high quality injector, injector holder, wideband o2, megasquirt 2 for on the fly wideband correction ... ticket to ride in my book.

if you need a much more elaborate solution you should not be looking for a 5psi simple entry level system ... if you are ... you're going overkill.

 

also ... i have experience with such systems over a span of six years running one on a personal vehicle and helping many others with similar systems. why did those engines not get destroyed over the 80k i put on my engine or hundreds of K combined on all the others ?

simple research and checking the plugs to assure all cylinders a are running at the same EGT resulting from a proper distribution of fuel.

 

or less ... it all matters on what tubo you use and intercooling ... you can pop a t25 with choked A/R on it and not intercool it and make 50hp extra ... that statement was made thinking conservatively since the ECU will not compensate for even 50hp on its own.

 

I lie crankshafts are different part #'s
parts catalog is weird I will do some more research.

 

[quote=intenseblu]or less ... it all matters on what tubo you use and intercooling ... you can pop a t25 with choked A/R on it and not intercool it and make 50hp extra ... that statement was made thinking conservatively since the ECU will not compensate for even 50hp on its own.[/quote


ahhh. back to the original question!
there are parameters of richness vs leaning out that the stock ecu must deal with.

other than making a broad statement of what the ecu can and cannot do, does anyone have any data on that parameter?

while the debate of how to accomplish boost the most effectivly for the dollar is informative, the original question deals with what the ecu can handle.
lots of bashing here with regard to boosting systems not viable without rewriting the software.
but i'm still looking for proof that the ecu can't handle minor boost.

i'm all for supporting some of the boosting concepts and have a few ideas of my own. but dialog with others is the foundation of learning. someone out there must have the absolute data the ecu's are programmed with.

one more to throw out...
if course we have all seen the performance increases posted by numerous companies on their reprogram.

would it not be possible to provide the additional boost info [5 psi], additional fuel pressure available...ect, and have the ecu programmed for optimal performance?

 

%20-25 long term fuel trim and %20-25 short term fuel trim ... it can only apply these adjustments to bring the idle and part throttle conditions to a 14.7 stoich burn. the final numbers are still applied to wide open throttle conditions but do not adjust based on wide open throttle air fuel ratio as the narrowband sensor is only accurate at 14.7...

and yes it would be possible to reprogram the ECU but at too high a cost and each build would have to be tuned as variances in what turbo was used or intercooler would affect tune required .... so unless a company makes a kit and has ECU's mass reprogrammed to be distributed with the kits then the cost would be very high. hell its going to be high no matter what you do for these cars ... so yes its all possible, how fat is your wallet ? how bad do you want it ?