New 6.5 TD owner

[arrowheadracing]

Hey guys, I just picked up a really nice 95 GMC 3/4 ton 4x4 long bed ext cab. My first big truck. The truck has 130,000 on it and was an original owner ( typical little old farm lady ). It has 3.73 gears and I just installed 285 75 16 tires. I have a couple of questions.

Day I bought the truck it stalled and from that day on it would surge and run bad. I replaced the oil pressure switch and that cured that problem. But I still think it lacks power. This is my first diesel. And I ve drag raced door <A TITLE="Click for more information about car" STYLE="text-decoration: none; border-bottom: medium solid green;" HREF="http://search.targetwords.com/u.search?x=5977|1||||cars|AA1VDw">car</A>s for close to 12 years and currently race motorcycles. So I know its not going to rip me into the next world. But I still think I shouldnt be beaten by a Geo metro to 50 mph. I ve run every check on it and everything seems to be on par. So it must just be lacking power to satisfy me.

So here is my list of upgrade I ll be doing in the next week or two.

4" exhaust ( is there much more noise with no muffler or any power gain without it ? not looking a top fuel car sound )

Chip

PMD cooler

Cone style airfilter with a elbow I ll make for it so its not right in front of the turbo.

I was looking at some boost controls, any recomendations ?

Also a home made air to air intercooler. Anybody have them and where and how big are they ?

Injectors ( cost vs mpg vs performance will they be worth my buck for some bang , or are they only going to help if I crank my boost up high ).

I am also looking to lift the truck 2-4 "s anyone with suggestions on where to look for a good kit.

I also run a small chrome and polishing business ( mostly motorcycle parts ) and will be doing some polishing on the aluminum parts under the hood. I ll post pictures of everything soon. I ll also be putting up a diesel page on my website, so if anyone wants to send a few pictures and a small description I ll post some pictures up.

Sorry so long winded, but thats just the way I am.

Glad to be here and look forward to hearing some reponses.

Thanks
Todd

WWW.arrowheadracing.com (http://WWW.arrowheadracing.com)

[rjschoolcraft]

Here's the road that I went down so far.

My 6.5 Performance Thread (http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=006650)

There will be more to come in the future.

The biggest hurdle is controlling EGT and engine coolant temperature. The intercooler is huge and increased boost really helps the 6.5.

[Spindrift]

Charge air cooling, in whatever form works best for you, is a critical element of any mod plan, especially if you plan to tow. Certainly, the ability to maintain boost is important. The jury is still out on whether or not boost of greater than 14 psi is productive.

[65turboman]

These guys are exactly right about the charge air cooling. Some of the best inexpensive improvements I made were getting a better flowing exhaust, and doing airbox mods. My 95 ran much better with just this. You are right on track with your plans. Also dont forget to add EGT and turbo boost gauges.

P.S. My truck is not too loud IMHO with out the muffler or cat
-----------------------
1995 2500HD 2wd RCLB, 6.5TD

[Keith Richards]

Every time I hear someone say they are a new owner, and truck seems way down on power,it leads me to beleive there is something wrong with the truck to begin with,before thinking about power mods,although theres nothing wrong with doing power mods.I was impressed from day one with the power of my stock 6.5 turbo diesel.But mine is a 98 and it has 4.10 gearing,Yours being a 95 may have left the factory with a little less power.I'd look further into the possibility of something not working properly,before doing mods.If you said towing heavy weight that would kind of be another story,but empty your truck should pretty burn rubber,mine did,and does more now with the simple mod of a 4"exhaust.Good luck

[arrowheadracing]

Well mine will burn the tires a touch out of the hole, and I can feel torque. But it just seems lazy after that. To jump from my 10 second GSXR into the truck , I realize its not going to compare. But it just seems to me like it should pull harder then it does. With about 2000 lbs of rocks in the back of it, it still felt the same power. Now I am not sure if your truck will smoke the tires from a dead stand still for 100 ft or what not. If it does and its stone stock, then something is definetly wrong with mine. Because I am lucky if it will go 5 ft before it hooks up and goes. I did forget to mention I will be installing a set of egt, trans and boost gauges. Also since I am avergaging about 17-18 mpg, I cant believe something else could be wrong ( if there is and I can get 20 mpg, then I ll be tickled ). I ve checked everything except the turbo boost. I havent yet replaced the fuel filter ( doing that this weekend ). So maybe I m bottlenecked there.
The GVW on my truck is 9000 lbs. It just seems alot to be asking of only 380 ft lbs to push ( if indeed they even make that much ).

Thanks for the info guys
Todd

[Dihrdbowti]

Any smoke when taking off under heavy throttle?

[arrowheadracing]

I dont get any smoke until I hit higher rpms. Sometimes its heavy black, mostly its light black. So I am just assuming sometimes I get a little better boost then other times. I checked my vacuum at the pump and its 25 "s , after the solenoid at the actuator its 15"s. So I assume that everything is working good since the acuator moves freely. No burps or hiccups since I ve replaced the oil pressure switch. But since I am still new to diesels ( certified gas mechanic ), I am learning thier quirks still.

Thanks

[99gmccrew]

You are "right on the mark" with your planned mods. Ive done pretty much the same thing that you have planned. If you do your own intercooler do a search on intercooler and you will get some good ideas. I did my own and saved some $$$. Check out my link. JK's boost controller works great on these engines combined with charged air cooling. He also sells a great IC. I enjoyed making my own version and saving some coin.

[JTodd]

What should 0-60 mph times be for a stock 6.5? It would be nice to know what it 'should' do stock. Based on what I am reading here, my Suburban appears to be underpowered compared to others (I don't think I could light the tires without a neutral drop, but won't try)

If I am on a flat stretch of road, tranny in drive, from a dead stop what should a stock 6.5 with 3.73 gears do?

[Kennedy]

Originally posted by ronniejoe:
Here's the road that I went down so far.

My 6.5 Performance Thread (http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=006650)

There will be more to come in the future.

The biggest hurdle is controlling EGT and engine coolant temperature. The intercooler is huge and increased boost really helps the 6.5.

No doubt about it. Recently dyno'd a stock '97 with hollow cat and muffler bypass pipe at 137.8HP. Then added my exhaust, retested and got 148.3HP. Added my boost controller and got another 5.5 for a total of 16HP gain and end result of 153.8HP. All without adding any fuel on a 130k+ truck with original injectors.

The truck did not have gauges to monitor EGT, BUT one observation was we dropped 1 full mark on the temp gauge. Initially, we hit straight up position during each run. Modified, we dropped one full segment with shorter fan clutch cycles between runs...

[JTodd]

I ran a 0-60 run this evening. It took approx. 14.5 sec. I just put it to the floor and let it go. It pulled evenly to a shift point of around 2800 rpm. Moderate to light black smoke. How does this compare to what it should do?

Thanks for the info.

[arrowheadracing]

It pulled to only 2800 , or 3800 ? In drive mine pedal to the metal shifts around 3700. My cruise rpm is 2300 at 65 mph. Thats with the stock 245 75 tires. I ll check mine out tomorrow and see what she does.

Todd

[JTodd]

Another attempt showed the 1st to 2nd shift at about 3200 or so. It smokes, but not a huge plume of black smoke. It is black, but not a lot of it. I first thought is to much exhaust back pressure. Any thoughts anyone?

[rjschoolcraft]

Originally posted by Spindrift:
The jury is still out on whether or not boost of greater than 14 psi is productive. This juror is convinced.

On the way to the Pull-Off last summer, my wastegate shaft partially bound up, limiting boost because the waste gate couldn't close all of the way. I could still make and sustain 11-12 psi in that condition while towing, but the power was noticeably down and my egt was way up. With all things working properly, I sustain 18 psi while towing in a hill or headwind. When that wastegate stuck and limited boost to about 12 psi, it was like someone threw out the anchor.

[Spindrift]

RJ,

Please be more specific as to what you have done to your truck in order to achieve the benefits of your truck's operation at higher than normal boost levels. Or, are you really saying that the rest of us have this same potential as well, and we just haven't come to the same realization?

[rjschoolcraft]

Actually, all of the specifics have been hashed over many times. Read through the thread I referenced in a post above. Here is a quote from a post in that thread...


Originally posted by ronniejoe:
16Ga,

Yeah, I'm kinda replowing some ground, here, but...

I think the fact that I'm still running stock compression, electronic injection pump and stock GM-4 turbo accentuates the point. At this point, the engine internals have not been touched. No balancing, no reduced compression, etc. I would like to build an 18:1 engine some day and bring the boost up even more with a bigger turbo, but that is just not in the budget at the moment. The Project Truck gave me hope when I thought I'd really "stepped in it" after buying this truck. Now, I hope I'm giving others even more hope as they consider their truck's futures.

For me, I'll be driving a 6.5 for quite some time before I can afford a Duramax. So, I've got to get everything I can out of the 6.5. Right now, I'm feeling pretty good. I'm also glad to see the hard numbers to back up my seat of the pants assessment of where I stood. It makes me convinced that the purchases I've made from Kennedy have been wise ones! smile.gif

It also backs up some of my comments from the past that have been rebutted somewhat (not maliciously). The boost levels and resultant power are significant here and revise some of the collective wisdom from the Page, IMHO. I've believed this for a while, but didn't have any hard data to support the belief. It's amazing what a couple of hours on a dynamometer with a guy who is as dedicated to getting this right as I am will do! :D

Thanks again John! :cool: I had to replace my turbo while at the Pull-Off (see the Rendezvous article (http://www.thedieselpage.com/rendez/ren04.htm)) because of a worn wastegate shaft and bushing. In a pinch, I replaced it with a stock rebuild unit.

My experiences with my Suburban lead me to believe that the collective wisdom concerning 12 psi boost maximum is in error. Would I produce more power at 18 psi boost with a bigger turbo than I do now? Sure. Do I produce more power at 18 psi boost with a GM-4 than I do at 12 psi? Absolutely. The dyno numbers and my towing experience show that.

Here's a quote from a doubter:
Originally posted by dieseldummy:
My trouble came from pushing to much boost on the stock turbo and pushing to much fuel. All it created was heat, so watch coolant and intake temps. and you'll be allright.

Also, on a side note, RJ I must disagree with your theory about regulating boost. Backpressure is critical to engine life, run too much backpressure for too long and you elevate temperatures and run against the "choke" point of the turbo. I know you will tell the tell of running sustained boost pressures of 15-17 psi or whatever the number is, and you have gotten a lot of miles out of your 6.5 this way. I commend you on this great accomplishment. My personal experience has stated the opposite of yours which is why I dissagree (sic) about boost control.
If this theory is right, I should see higher egt at the higher boost pressures. I don't. My egt is lower at 18 psi than it was when the bushing failed limiting me to 12 psi...by a lot!

At least one other person has reported running higher than that (vac pump straight to waste gate actuator yielding 20+ psi) with similar results.

In answer to your question, yes I think all could benefit from higher boost (with charge air cooling, of course). If I get the opportunity, I would like to upgrade my turbocharger to run higher boost yet.