Big 6.5 Test

[Acesneights1]

Sounds like maybe he needs a new Turbo that is less restrictive, HUMMMMM:biggrin5: that will also give him cooler intake temps.

It has a GM4. Not sure what you guys mean when you say less restrictive ???:confused5:

 

[Acesneights1]

Installing an I/C will help with temperatures some, but the excessive turbine restriction (backpressure) will still be there. The EGT's will also suffer under the rule of the GM-X turbo, driving that much more heat into the heads and consequently the cooling system.

He would likely have better results running just enough boost to keep his exhaust "clear" under load at WOT...

Regards,

Goldsburg

OK now I'm really lost. Bill H told me more boost was better for keeping it cool because I thought maybe I needed to cut the turbomaster back.

 

[Slim Shady]

OK now I'm really lost. Bill H told me more boost was better for keeping it cool because I thought maybe I needed to cut the turbomaster back.

I think Goldsburg and I were thinking the same thing but maybe for different reasons.

The GM -4 is way to small to make 14 psi boost without adding excessive amounts of exhaust back pressure and intake air heat, and that keeps heat in the motor.

When the GM-4 is making 14 psi boost it is near normal for intake air temps to be in the 200 degree range on a 90 degree day. If you drop your boost to around 9 or ten psi you may see your engine heat stay some what lower. You are providing less pressure at a cooler intake air temp. FLOW or CFM is where it is at not PSI the two go hand in hand to a certain degree then it is all about providing CFM not just pressure.

Lets talk air compressors, after all that is all a turbo really is, it is not anything more spooky than that.

If I have a cheap air compressor that flows 12cfm at 90 psi and I have a good 2 stage compressor at 125 psi and 23 cfm which compressor is going to have a cooler air flow at the rated pressure and cfm.

Neither they are both at there maximum rated flow at pressure, so lets keep the 125 psi compressor and drop the pressure down to 50 psi and still at 23cfm, now we have cooler air and more flow than the cheap compressor does at 90 psi and 12 cfm. A much more efficient setup.

So your GM -4 was not designed to provide 14 psi for any given time on top of that you restricted the exhaust by limiting the waste gate so you are keeping all that heat in the engine just long enough to get the heat soak going when running her hard. Cumulative heat soak and we know cast iron loves to retain heat, that is why they used to make steam radiators out of it.

 

[Acesneights1]

So GM-8 maybe the way to go ? I'm probably in the end just going to sell the camper. I don't have the money to buy a Dmax plus I love my 2 door. I think in the end I may just be asking too much from it. When I'm not towing the truck is fine. Besides right now I'm looking at an IP so camper sale may fund it. I've dumped thousands into this truck in upgrades and realistically speaking it tows no better heat wise than when I started. it does un a hell of alot better and is fun to drive and definatley turns heads when the 4 inch exhaust and diesel sounds come rollin by. The weird thing is my 2000 should have no problem and it overheats exactly the same as this truck does.

 

[Acesneights1]

The sad part of all this is the truck power wise pulls that thing like it's nothing. The truck literally will break the tires loose around town(no camper of course )
I really feel at this point in the game it has more pulling power than my old 99 Stroke.

 

[Slim Shady]

-

I wouldn't give up on your truck. I don't think you need a new turbo. We just need to find your problem. It is not a big problem or expensive, just hard to find. So don't give up.

 

[jcool]

I wouldn't give up on your truck. I don't think you need a new turbo. We just need to find your problem. It is not a big problem or expensive, just hard to find. So don't give up.

hot air from cooling stack going into intake. thats what I think you should correct next and see where that gets you.

 

[JiFaire]

Kenny - have you done the TCC lock mod yet?

I know it was the final step of the puzzle for another guy I know that tows with his 2-dr Tahoe... that and finding the 'just right' sweet spot for towing (the speed at which everything stayed cool - in terms of gear, rpm, speed). Now he pulls a big load just fine, and his mods look just like yours. 95 tahoe, too, with a GM-4.

 

[Turbine Doc]

hot air from cooling stack going into intake. thats what I think you should correct next and see where that gets you.

Cooling stack ???? you've lost me, there

 

[JiFaire]

Cooling stack ???? you've lost me, there

I think he's talking about the rad/AC Condenser/Tranny cooler/etc ...

Kenny cut up his stock airbox, so it's drawing in hot underhood air; the stuff is plenty hot after it passes through all those rads. Never noticed the significance of that initially, but Justin might have a good point.

Same thing happens to guys who use Walt's intake and try to pull hard.

 

[nvmtnlion]

No it doesn't :reddevil:


Well, if you build a box around it and remove the right front turn signal lens and replace it with a piece of expanded metal :lol:

 

[Turbine Doc]

. I don't quite undertstand what you said about Map pis vs Turbo ?

PSIA vs PSIG is what I was talking about, the MAP sensor (Manifold Absolute Pressure) is a precision sensor that is biased by prevailing atmospheric conditions so a scan tool reading is atmospheric plus what the turbo is adding read in PSIA or kPa, most boost gauges are in psig reflecting straight turbo boost output without complensating for atmospheric conditions. So in order to correlate what a common boost gauge is displaying vs what a scanner is showing you need to subtract out the barometric pressure.

Baro conditions do have effect on total boost volume delivered so PCM takes that into account for proper fuel/boost scheduling, hence need for more precise reading ergo a psia/kPa from MAP sensor.

In earlier post you show 27.81 psi boost which ain't happnin with a GM-X any turbo, unless that is including baro nominal 14.7 at sea level maybe more maybe less so when subtracting out baro conditions (using 14.7 nominal) gives you 13.1 psig, now depending on temp of the day anything above 10 psig is where you really need to start looking at some sort of post turbo cooling either WMI or ATA/WTA IC.

260 F IAT isn't mega hot but is getting up there, plus from testing results when looking at Mitsu TD07-22 turbo and China (clone)turbo back pressures that much boost are knocking on 30+ psig with a GM-8 which has better outlet flow than the GM-4, which is kinda like a blocked soot trap.

So I'd look at everything again, possibly put stats in boiling water with meat thermometer to see that they are opening properly, also look at the lock up mod Jif was referring to. Are you losing coolant, have you ever done a cooling system pressurization test, is there such a thing as too much water wetter, this new rad, is it possible it is too big, hear me out I'm just doing some out loud thinking of other possibilites, for why yours is different from so many others.

Heat exchangers are sized for flow they expect to see vs temp drop, it is possible that at speed your rad is flowing so fast that coolant isn't staying in the rad long enough to transfer the heat to the core for air to pull heat, any idea what the trans temps are, I had to add the deep pan and Deraile extra trans cooler to mine but my occasional 18K load needs all cooling I can give it.

 

[Turbine Doc]

I think he's talking about the rad/AC Condenser/Tranny cooler/etc ...

Kenny cut up his stock airbox, so it's drawing in hot underhood air; the stuff is plenty hot after it passes through all those rads. Never noticed the significance of that initially, but Justin might have a good point.

Same thing happens to guys who use Walt's intake and try to pull hard.

Ahhh I didn't recall that mod, some will argue the point it don't matter to suck in underhood air, in normal driving difference would be negligible, but towing where you are really generating a lot of heat rate thru all the heat exchangers, it ain't helping any.

 

[jcool]

Ahhh I didn't recall that mod, some will argue the point it don't matter to suck in underhood air, in normal driving difference would be negligible, but towing where you are really generating a lot of heat rate thru all the heat exchangers, it ain't helping any.

exactly, putting a load on the engine causes a lot of heat, and to circle it back through only produces more...

 

[Acesneights1]

exactly, putting a load on the engine causes a lot of heat, and to circle it back through only produces more...

The airbox cut open mod is the one on Kennedys site. All I did was lose the snorkel(actually it wasn't there to begin with) and open the box a little more. it still draws air from the fender not the eng compartment. I'm leaning more towards needing an intercooler. The only thing i was going to try first since it will only cost me 30$ in R134a is yanking the a/c cooler out and taking it for a drive. If I dropped the truck down to 45-50 MPH on hills the temps dropped some.

 

[jcool]

The airbox cut open mod is the one on Kennedys site. All I did was lose the snorkel(actually it wasn't there to begin with) and open the box a little more. it still draws air from the fender not the eng compartment. I'm leaning more towards needing an intercooler. The only thing i was going to try first since it will only cost me 30$ in R134a is yanking the a/c cooler out and taking it for a drive. If I dropped the truck down to 45-50 MPH on hills the temps dropped some.

but without the snorkel(unless its something attached to the exhaust manifold) and the air box open more under the hood it will be drawing in more air from behind the cooling stack which is already going to be hot... an intercooler is a good idea but will only cause backpressure for an already overworked turbo. I am not trying to offend you by any means. Personally I would try to seal off the intake under the hood and tube it either under the truck or soley in the fender if possible. hope that makes some sense....:confused5:

 

[Acesneights1]

J, no offense at all I just don't think I'm explaining what i did right so as confucoius(spelled that one good huh ?)say..picture worth 1000 words.

 

[Acesneights1]

More of when I cut it open.

 

[Acesneights1]

Kenny - have you done the TCC lock mod yet?

I know it was the final step of the puzzle for another guy I know that tows with his 2-dr Tahoe... that and finding the 'just right' sweet spot for towing (the speed at which everything stayed cool - in terms of gear, rpm, speed). Now he pulls a big load just fine, and his mods look just like yours. 95 tahoe, too, with a GM-4.

No I accidentally deleted the PM you sent me on how to do it on the old site. Trans temp looked ok on GMTDscan.

 

[JiFaire]

I'll dig up the URL for that mod again for ya. It makes a big difference... the tranny temp doesn't have to be that high, but what it does is prevent the engine from shedding heat.

Trust me on this one... it's a 15-minute mod that costs $5 and makes a big difference.

PS - I did Kennedy's airbox mod too, and it didn't hurt my IATs, so I doubt that's your problem.