95 K3500

[Mayson]

Hello everyone. Looking to chip an OBD1. Reasonably fresh tranny, recent turbo and injectors. Re n Re engine but not sure where it originated. appears to run well. Worried that 6.5's have a weak crank. not interested in overpowering, maybe 40 -50 hp. will probably need new down pipe ??? Suggestions??? Just used for towing 14,000 lb. equipment trailer as high as 10 -12000 lbs. deck-over. thanks for any useful knowledge. I like my truck.

 

[Will L.]

Welcome.
Gonna start with the issue of “chip”. Epa is up everyone’s backside and you could be a plant/ snitch. So even if there were places we know can do it- no one is gonna make suggestions currently.

Now set that aside without getting feelings hurt hopefully is you are for real.
There is a ton of guys here that know these engines at amazing levels.
The power you want is easily and safely done without a chip anyways.

Read the stickies in the library. So much info that will make your engine better in every way and make it last longer.

Yes the 6.5 is a weak bottom end. Do the improvements to sustain its life.
Fill out your signature with truck details and modifications so we don’t repeat things that you already know.

First must do items:
Oil cooler hoses are fail prone and ruin engine in 5 seconds
Balancer/ belt drive pulley is huge weak point and need replacement every 100k miles, or fluidampr last 500,000 miles and does better job.
Coolant temps: 200f good, 210 danger, 220 pull over now & let idle down. Factory gauge is garbage. Cooling improvements are known- there are many BS sales pitched items that actually do harm. So speak up/ show what you’re running.

Air intake needs improved but many do it wrong- read threads.
4” exhaust is target.
Hole your new turbo isn’t a gm. If so cry and replace it with a better one- this is INSANELY CRITICAL to power and mpg improvements at same time. Hilariously it will also be cleaner emissions. EPA wont understand it- but its real.
Many crap-tastic injector sellers around- who and what did you buy. Many make it worse and can ruin pistons.

No one likes to pull a newly rebuilt engine. But with a new one you can do a few improvements inside now to make it last many many years. Depends on budget what to do and how much it helps.
Balanced rotating assembly and adding TSP girdle will seriously help that weak bottom end. Spend another couple hundred bucks on gapless rings and you won’t believe how clean your oil stays along with added life before blow by.
Obviously way more but hope you get the idea.

Btw, show some pics- we all love show n tell like its 3rd grade still. Seriously though we like pics and more we see of what you have the more we might catch little details of things you don’t know.

 

[dbrannon79]

@Mayson welcome the the forum. there are a few folks here including myself that dabble in the old OBD1 tuning for personal use. before doing any electronic upgrades, what all have you done parts wise to your rig? take in all you can from @Will L. he is very knowledgeable on these diesel rigs so are others here more so than me.

things to do before any tuning, everything Will said above. the exhaust and turbo are two of the biggest downfalls of these engines in a stock setup next to keeping the engine cool. Start off on the low cost end and get a boost gauge installed and install a manual temp gauge with the probe in the passenger side head up by the #8 cylinder. that cylinder is the hottest part of the engine. temps are best kept under 210. anything over that and you need to ease off the go pedal and let her keep cool. 230 at that cylinder and it's too late, cooking the rings or worse. then move on to getting a EGT gauge installed in the manifold just under the turbo so you can make sure never to go over 1200 deg.

lots of us here can help you along suggesting what we've experienced that works best for a given use case. Were all here to help

 

[Will L.]

Thanks @dbrannon79 for the vote of confidence- but there are way smarter guys than me here for this rig. I just shoot my mouth of and have a quick draw at it!

@Mayson
Tuning would be my last step on it. The core of the design has many errors that correcting them gives no only more power but longer life and sometimes better mpg as well.

Be specific please, and putting these in your signature line helps a lot because it will pop up automatically w/ each post- that saves hassle when we are trying to work out options on improvements or repairs.

What turbo?
What injectors & from where?
What air intake system?
What exhaust system?

Really quick- going to a 4” Exhaust and proper sized turbo instead of the (well coined by @WarWagon in his article) asthma attack turbo will give the trifecta- better power, mpg, longer life.

The weak bottom end is a serious issue. 2 things to do asap and a detail:
1. Check the harmonic balancer and belt drive pulley for rubber cracking or external ring shift. Seriously grab the balancer ring and try dislodging it- if you can it was about to go anyways. Only 2 good options for replacing and many bad.
2. Check oil cooler hoses. If seeping, or brittle- change them now for some aftermarket hoses from Leroy or get a set made at a hydraulic shop with actual hydraulic hose like used on a backhoe.
Both of these give no warning and destroy the engine in seconds.

Final thing is factory temp gauge is crap. Once you know it’s accurate 200 is ok, 210 watch the gauge more than the road,220 pull over and let it idle back to normal.
Heat is actually the #1 killer of this engine.

 

[dbrannon79]

Hey, I have learnt everything about my truck from you guys here. if it wasn't for this forum and everyone here I'm sure I would have blown up mine within the first 6 months to a year of owning it!

 

[MrMarty51]

Welcome to the forum Mayson.
One word of advice, if Your engine is running too warm, do not buy one of them flo-cooler coolant pumps.
Only the balance flow GM pump is tested and proven.

 

[Will L.]

Hey- never directly answered the question and meant to.
If you are done with all that and still want to tune:

 

[SnowDrift]

Mayson, welcome!

Did you stick around for responses?