Power advice

[Billman]

I need a little advice from the more experienced than I that tow a heavy load...

I'm towing (12k), and want a little more power. Already have hi-flow filter, intercooler, and exhaust. Seriously considering re-flash and injectors. Just something to help keep trans locked up a little more. Between computer and injectors, I'm told 40 rwhp is possible.

Does anyone have similar setup? How many miles since upgrades? Reliability issues?

I've spoke with a few people, some for and some against. It's the ones that are against these upgrades that make me wonder.

It seems head gaskets, small numbers of head bolts, and cracking blocks and heads become a lot more common.

I don't beat my stuff up. I keep EGT pre-turbo below 1200* and maintenance is excellant.

Would like to hear any and all ideas...

[jspringator]

Do you have boost controller? I read one of Kennedy's posts where he was praising the virtues of the stock PCM flash. I have Kennedy's boost controller with no intercoler and am pleased with the results. Also, had my "timing" set to -1.5; it had been set at 0. This made a huge power difference. With an intercooler, you could safely pump up the boost and the fuel(injectors) for more power.

[Billman]

Yes James, I have the boost controller set to max 12-14psi just before it kicks out of overdrive. I just can't say that boost makes a big power increase though. I also have the #9 resistor with no seat of the pants improvement. Same for the timing -1.94. I'm sure all of these improvements work together, but it's tough to see. This is where a dyno is needed. An HONEST one. But in reality, my truck will never see a dyno.

My fear is adding 75-80mm of fuel while trying to keep the cylinder heads attached to the block.

I have read about the 99 and up programming. How would I go about updating my 97?

[Kennedy]

wbucha from Little Neck? did a steering column swap (Passlock) and used the 98+ programming in his Tahoe. IMHO, this programming is the best out there. A reflash WILL give you more upper rpm fueling, but not much.

I dyno tested a 99 stock vs. the towing program for my 96. The 99 program had 20lb/ft on the performance program, and the performance program had 8 HP. This was on a Mustang dyno with the "Crayola" drawing charts. Had I been on a Superflow...


The OE programs from 96-97 seem to have 62mm max. The 98+ have a "torque bulge" to 75-77 mm around 2500 RPM, then drop back to 62mm.

The reflash IMHO seems to lack one key thing: LOGIC. If I do a foot to floor brake stand, fuel goes to max regardless of RPM. Tying the fuel rate to the APP DOES give more response, but this is more of an illusion. The timing is also better in the OE programming as the reflash seems to be more flat like the 94-5 chip data was just loaded forward.


The turbo is the bottleneck...

[GMCfourX4]

I took my truck to a ::cough:: dealership while it was still under the injection pump warranty, and even though they didn't do a damn thing about my PMD (the service manager said "That's the fastest 6.5 I've ever driven, and I drove it over 90 miles and didn't have a problem"... odometer showed 23 miles) they did re-flash my computer, and I have verified with a Tech 2 that it puts out 76 or 78 mm of fuel. If you have a friendly dealer, you might just be able to ask them to re-flash?

-Chris

[DChristie]

Stealership?

He didn't lie he just didn't complete the sentence. "That's the fastest 6.5 I've ever driven, and I drove it over 90 miles PER HOUR and didn't have a problem"... odometer showed 23 miles)

[britannic]

Originally posted by Billman:
Yes James, I have the boost controller set to max 12-14psi just before it kicks out of overdrive. I just can't say that boost makes a big power increase though. I also have the #9 resistor with no seat of the pants improvement. Same for the timing -1.94. I'm sure all of these improvements work together, but it's tough to see. This is where a dyno is needed. An HONEST one. But in reality, my truck will never see a dyno.

My fear is adding 75-80mm of fuel while trying to keep the cylinder heads attached to the block.

I have read about the 99 and up programming. How would I go about updating my 97?

I wouldn't worry too much about keeping the heads attached to the block - combustion heat/pressures and EGTs are the real issues to keep an eye on. It's actually possible to have safe EGTs as measured at the probe, but have the ignition so advanced (on the mech. pump at any rate) that the glow plug tips melt off and the piston crowns go plastic and dish until destroyed.

I'm running 76-80mm3 and boost has been as high as 18psi (I've limited it to 14psi now, since without an intercooler it's a waste to go any higher) in my humble 6.2L. EGTs never exceed 1100F max (average 950-1050F) and since a bad experience with a timing chain that had over 1" of play (I compensated for the chain wear at the pump, but it turned out that at certain engine speeds, #3 and #6 cylinders were too advanced and melted the glow plug tips), I installed timing gears from John Kennedy (best power upgrade yet - especially in an older engine) and now my engine is consistently timed for all cylinders.

[patrick m.]

you have all of the ingredients but one
A BIG FAT NEW TURBO!
there are many to chose from.
my 95 loves its new turbo

[MJEasly]

Has anybody looked into power flowing (extrudehone)the turbine side of the turbo? Some turbo guys I've talked with say it makes a big improvement. Others say a waste of money.

[Billman]

I think I found someone other than a dealer to do a computer flash on my PCM. According to GM, the PCM itself is the same part number from 97-01. All I need to do is have mine re-flashed for 99-00? Does this sound right?

When my truck went to the dealer 2 years ago, they replaced the injector pump/driver and told me they upgraded my PCM. Do I already have 99-00 programming?

I have access to a Tech II. How would I do a baseline test for before/after?

Where exactly is maximum fuel delivered?

britannic: I'm NOT worried about 15psi of boost. I'm AM worried about 15psi of boost for extended periods of time. It's not uncommon to tow my trailer and watch the boost gauge stay at 10psi for an hour or two. Sometimes going up hills and dropping out of OD. This is where I imagine max fuel to be at along with hi boost.

I have seen 14psi for 3-4 min. steady. Now add more fuel, what is going to happen?

If my EGT reads 1100-1200*, what do you think the combustion temperatures are?