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Upgrading Turbo on Everyday Use 1994 BLAZER 2DR 6.5. OPINIONS?

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2DRTURBO

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TTS is a great website for learning all kinds of great stuff about upgrading the 6.5- fairly new to the site but really enjoying my time here. Question for those of you who might be interested, knowledgable, experienced, or simply opinionated in this area....

What do you all think of putting an upgraded turbo on an everyday driven 2dr Blazer/Tahoe. I rarely tow and this is just a fun everyday vehicle for me. I just love the truck and have enjoyed increasing the power and maximizing power and overall soundness of the motor. I have a strong upgraded motor with ALL the usual stuff, chip, cooling, TM, Kennedy injectors, F intake, vac delete, 3.5 Kennedy exhaust, cooling upgrades, gauges, etc etc. The GM4 i have now is in great shape and works great with no issues. Its does, well, fine....

I have read ALL about the various turbos available and know the drill with holsets, ATT, etc. And I know some people are fans of one versus the other, etc. It seems like most people are doing the upgrades for better towing/ But my question is, for a 4wD 1/2 ton SUV that isn't used for towing heavy does upgrading the turbo make sense? Does it make it a lot quicker around town? Better off the line? Better top end on the highway. Basically, is it worth doing and will the seat of my pants increase in power be worth the expense? Any downsides to ATT or Holsets for this particular application? Any opinion which makes more sense for me to do if ANY?
 
Looks like we were typing at about the same time. I just posed similar question but I tow some occassionally and need injectors too. But, I don't tow anything like some folks on here though. No 10k plus trailers for my old girl.
I am sure we will get some good feedback. This is by far the best forum I have been on.
Good Luck!
 
Look at center mount thread.

Anyways just changing the turbo will allow your engine to breathe better on its own and more efficiently make boost. Resulting in more MPG if that's what your after. I have an hx40wII but I am in mid build with truck up on jack stands and having never ran that turbo, but what I can tell you is that the stock gm turbos are a severe choke point on this motor. ATT or hx40 will be better than what you have on there that's for sure. I am considering going the center mount setup at present also so pm me about an hx40 if your interested ;)
Sorry for the plug lol
 
The MPG gain with ATT is a big plus for me with cost of fuel being so high now 1-3 mpg gain depending on health and overall condition of your ride has been what many see when swapping to ATT
 
The HX40 is a great daily driver turbo. Better response and much improved Pyro temps, lower boost at cruise speeds, and better MPG.

Sounds like you already have the basic mods to make a turbo upgrade worth it!

I would really be hard pressed to go back to a GM-X turbo :(
 
My truck is basically the same as yours. My HX40w-ii is by far my favorite mod even though i needed the other mods to use it... i run 20psi peak with stock internals.. cheering about it so far
 
I would go HX40 if i was just cruising around town and wanting more down low/off the line snap. At cruising rpm's the hx40 likely has better flow than the gmx so i wouldnt be worried there either. The ATT has even less back pressure (just by story translating, no real numbers yet) for better performace under high load situations when the HX40 would likely be wastegating.
 
After running both turbo's...
Both are a good improvement.

You didn't ask about ease of install and you should. It is night and day.
The ATT kit wins hands down with 2 cuts needed and 2+2 clamps needed. The ATT is the simplest to install and no wastegate to adjust or mess with. Quality control can catch a housing difference and give you a consistent turbo you can count on for being within a specific specification.

The HX40II comes from fleabay and requires several custom parts. Like a downpipe, intake mods, battery post mod, different air filter. If you have a weekend to kill and lots of extra parts to make it work. Be aware that fleabay is like a box of chocolates because you never know what you are going to get. 10 or 12 blade and the seller appears clueless between both and likely more flavors. Did I mention taking a grinder to the compressor v-band clamp to eliminate it? Just a FYI.

If you mash the throttle to the floor you will notice a difference. (I can roll coal on a GM3 with the fuel turned up, altitude, load...)
The GM3 will spool about the time the starter kicks out. It then chokes the living MPG out of your engine.
The HX40II will generate boost at lower RPM than the ATT. The HX40II chokes just about redline and isn't much good over it. I start to get smoke at the top RPM. (Do you really want to run over the 3400 RPM redline? Some take it to 4000RPM. Just saying.)
The ATT starts to generate boost around 1700 RPM and will enthusiastically take you over redline and then some. Smoke free past 2000 RPM.

From low throttle to full throttle while moving the smaller turbo's smoke for less time.

SOTP and by sound of the turbos the HX40II is generating boost at lower RPM. However I am not as impressed with it foot to the floor in the upper RPM as my butt says the ATT pulls harder in the upper RPM's.

I have 4.10's in the pickup and 3.73's in the burb. The 4.10's allow the ATT to be in sweet spot easy. The heaver Suburban doesn't feel as quick and smokes more than I like with BOTH turbo's. Once the turbo generates boost the smoke clears.

Everything is a trade off - pick one or go with a variable turbo. Cause you get off the line or top end with a middle turbo thrown in there. As long as you are removing the factory turbo you will get an improvement. Off the line the factory turbo wins - only to get stomped past 2200 RPM bad enough to not make the off the line win matter.

Absolutely more load makes the bigger turbo better. Light load doesn't have time or the heat to generate max boost from a large turbo. I see a 3-4 LB difference as in higher boost with a trailer WOT up a hill with the ATT. I am still at 14 lbs unloaded and 18 lbs loaded boost with lower IAT and EGT than a GM3 on the same fuel setting. The fuel setting was at 14 PSI with the GM3 and 1350 EGT. I am at 1000 EGT with the ATT on the same DB2 fuel setting. The bigger turbo's can take more fuel... And I have pushed the ATT past 1450 EGT sustained on a hill with the 1995 DS4.
 
The ATT has even less back pressure (just by story translating, no real numbers yet) for better performace under high load situations when the HX40 would likely be wastegating.
Click to expand...

Just to be clear on this statement, the HX40 will not hit the wastegate until 20 PSI in stock format.

Again around town non-towing the HX40 has been great for me. I agree that it is more "custom" work to install than a ATT, ATT clear winner for install. I just like the early boost that the HX40 offers over the rolling boost from the ATT. From what I hear since I have only ran the HX40. IMO they are different turbos for different jobs. ATT for towing. HX40 light towing and everyday driving.

And yes it is easy to pound out 20 PSI with the HX40. Granted I drive pretty conservatively and very rarely go over 15 PSI.

I still need to address the FTB mod, so I am not in a good position to comment on top end sustained pulling until I am 100% solid on fuel delivery.
 
THANKS

Wow, thanks, incredibly useful, relevant comments, esp Warwagon who is obviously in a unique position to comment on all this having run both. Awesome that you have done this and share with all of us your findings. Much appreciated. Both turbos obviously make sense and will offer nice improvement over stock. What appeals to me about ATT is: Lower Boost Level, which bodes well for longevity on this motor considering its high compression engine and it has its weaknesses we are all well aware of. Stuffing 15-20psi into this motor makes my 18 year old head gaskets shake with fear. Also, ease of install is certainly a factor although not a huge one for me. I am going to own this truck for years so a few more hours or even days of install isn't the end of the world. But the sourcing issues on the Holsets are a risk and pain. Or you just pony up for a genuine one...but that doesn't make $ense.

WarWagon said:
Both are a good improvement.

You didn't ask about ease of install and you should. It is night and day.
The ATT kit wins hands down with 2 cuts needed and 2+2 clamps needed. The ATT is the simplest to install and no wastegate to adjust or mess with. Quality control can catch a housing difference and give you a consistent turbo you can count on for being within a specific specification.

The HX40II comes from fleabay and requires several custom parts. Like a downpipe, intake mods, battery post mod, different air filter. If you have a weekend to kill and lots of extra parts to make it work. Be aware that fleabay is like a box of chocolates because you never know what you are going to get. 10 or 12 blade and the seller appears clueless between both and likely more flavors. Did I mention taking a grinder to the compressor v-band clamp to eliminate it? Just a FYI.

If you mash the throttle to the floor you will notice a difference. (I can roll coal on a GM3 with the fuel turned up, altitude, load...)
The GM3 will spool about the time the starter kicks out. It then chokes the living MPG out of your engine.
The HX40II will generate boost at lower RPM than the ATT. The HX40II chokes just about redline and isn't much good over it. I start to get smoke at the top RPM. (Do you really want to run over the 3400 RPM redline? Some take it to 4000RPM. Just saying.)
The ATT starts to generate boost around 1700 RPM and will enthusiastically take you over redline and then some. Smoke free past 2000 RPM.

From low throttle to full throttle while moving the smaller turbo's smoke for less time.

SOTP and by sound of the turbos the HX40II is generating boost at lower RPM. However I am not as impressed with it foot to the floor in the upper RPM as my butt says the ATT pulls harder in the upper RPM's.

I have 4.10's in the pickup and 3.73's in the burb. The 4.10's allow the ATT to be in sweet spot easy. The heaver Suburban doesn't feel as quick and smokes more than I like with BOTH turbo's. Once the turbo generates boost the smoke clears.

Everything is a trade off - pick one or go with a variable turbo. Cause you get off the line or top end with a middle turbo thrown in there. As long as you are removing the factory turbo you will get an improvement. Off the line the factory turbo wins - only to get stomped past 2200 RPM bad enough to not make the off the line win matter.

Absolutely more load makes the bigger turbo better. Light load doesn't have time or the heat to generate max boost from a large turbo. I see a 3-4 LB difference as in higher boost with a trailer WOT up a hill with the ATT. I am still at 14 lbs unloaded and 18 lbs loaded boost with lower IAT and EGT than a GM3 on the same fuel setting. The fuel setting was at 14 PSI with the GM3 and 1350 EGT. I am at 1000 EGT with the ATT on the same DB2 fuel setting. The bigger turbo's can take more fuel... And I have pushed the ATT past 1450 EGT sustained on a hill with the 1995 DS4.
Click to expand...
 
Last edited by a moderator:
I am currently working on a wh1c, basically an hx35. I picked up the turbo for basically nothing ( traded parts i got for free and wasnt going to use). I am mainly looking for mpg increase and some overall performance. If i had the cash i prolly would have just bought the att for install ease. But i just couldnt beat the price...
 
2DRTURBO said:
Wow, thanks, incredibly useful, relevant comments, esp Warwagon who is obviously in a unique position to comment on all this having run both. Awesome that you have done this and share with all of us your findings. Much appreciated. Both turbos obviously make sense and will offer nice improvement over stock. What appeals to me about ATT is: Lower Boost Level, which bodes well for longevity on this motor considering its high compression engine and it has its weaknesses we are all well aware of. Stuffing 15-20psi into this motor makes my 18 year old head gaskets shake with fear. Also, ease of install is certainly a factor although not a huge one for me. I am going to own this truck for years so a few more hours or even days of install isn't the end of the world. But the sourcing issues on the Holsets are a risk and pain. Or you just pony up for a genuine one...but that doesn't make $ense.

[/QUOTE:]
Both are a good improvement.

You didn't ask about ease of install and you should. It is night and day.
The ATT kit wins hands down with 2 cuts needed and 2+2 clamps needed. The ATT is the simplest to install and no wastegate to adjust or mess with. Quality control can catch a housing difference and give you a consistent turbo you can count on for being within a specific specification.

The HX40II comes from fleabay and requires several custom parts. Like a downpipe, intake mods, battery post mod, different air filter. If you have a weekend to kill and lots of extra parts to make it work. Be aware that fleabay is like a box of chocolates because you never know what you are going to get. 10 or 12 blade and the seller appears clueless between both and likely more flavors. Did I mention taking a grinder to the compressor v-band clamp to eliminate it? Just a FYI.

If you mash the throttle to the floor you will notice a difference. (I can roll coal on a GM3 with the fuel turned up, altitude, load...)
The GM3 will spool about the time the starter kicks out. It then chokes the living MPG out of your engine.
The HX40II will generate boost at lower RPM than the ATT. The HX40II chokes just about redline and isn't much good over it. I start to get smoke at the top RPM. (Do you really want to run over the 3400 RPM redline? Some take it to 4000RPM. Just saying.)
The ATT starts to generate boost around 1700 RPM and will enthusiastically take you over redline and then some. Smoke free past 2000 RPM.

From low throttle to full throttle while moving the smaller turbo's smoke for less time.

SOTP and by sound of the turbos the HX40II is generating boost at lower RPM. However I am not as impressed with it foot to the floor in the upper RPM as my butt says the ATT pulls harder in the upper RPM's.

I have 4.10's in the pickup and 3.73's in the burb. The 4.10's allow the ATT to be in sweet spot easy. The heaver Suburban doesn't feel as quick and smokes more than I like with BOTH turbo's. Once the turbo generates boost the smoke clears.

Everything is a trade off - pick one or go with a variable turbo. Cause you get off the line or top end with a middle turbo thrown in there. As long as you are removing the factory turbo you will get an improvement. Off the line the factory turbo wins - only to get stomped past 2200 RPM bad enough to not make the off the line win matter.

Absolutely more load makes the bigger turbo better. Light load doesn't have time or the heat to generate max boost from a large turbo. I see a 3-4 LB difference as in higher boost with a trailer WOT up a hill with the ATT. I am still at 14 lbs unloaded and 18 lbs loaded boost with lower IAT and EGT than a GM3 on the same fuel setting. The fuel setting was at 14 PSI with the GM3 and 1350 EGT. I am at 1000 EGT with the ATT on the same DB2 fuel setting. The bigger turbo's can take more fuel... And I have pushed the ATT past 1450 EGT sustained on a hill with the 1995 DS4.
Click to expand...
[/QUOTE]


The ATT makes a great daily driver, and it has room to grow with your modifications IF that is what you want to do. There is not much difference between acceleration on the Gm 8 and the ATT we did tests with a G tech there was only a marginal difference in acceleration data. Not enough to even mention.

I use my truck for a daily driver and have no issues with it, I can't say anything about the HX clone because I don't know first hand so I don't say. If I say something I have first hand experience with it not just hearsay.

I do know that I would be hard pressed to put 15 to 20 psi through my engine at 1400 rpm or lower . Bottom ends go out from that type of stress. PM me for my number and we can discuss the pros and cons,
 
I Build and sell almost everything you need for the HX40II install
Click to expand...

x3 Bruce can get you setup for the HX40 setup if you choose that route, and is what I am running.

Slim is your man for the ATT if you choose that route.

Either way you are waaaay better off than the stock GM-X!!!
 
I'm surely going in one direction or another- I'm finishing a few other housekeeping, main't and upgrades such as Kennedy injectors at the moment. But once I'm done getting everything all dialed in the turbo is next. Tough decision, seems like really I'd see such an improvement with any of the discussed options over the gmx... Can't really go wrong
 
The ATT turbo has been proven as a real good dependable set up, so far the CKO40II's have been doing real well ether way you will have a hard time keeping the smile off you face when you step on it and when you pull up to the Diesel pump
 
I have personal dyno experience with both the GM-3 and the ATT and can hands down tell you to ditch the factory turbo immediately. For just daily driving around, I assume the CKO40 would be a great option, but seems to require a little more fab work. If you are just the weekend warrior, then the ATT was a breeze to install. It just depends on what you want. I haven't had a chance with the CKO40 but I hear a lot of great things, and I am currently running the ATT now. I love it. My top end improved substantially. I just towed a 9K lbs trailer yesterday with ease. And that is considering I live at 5200ft above sea level. On a stock motor, the ATT I believe leaves way more room for improvement if you need it. Either way, both turbo's are great choices, as long as you are not running factory anymore :)
 
With regard to which is best, I'll weigh in that while I was part of the R&D crew of the ATT and I give a nod there plus we have a ATT vendor that supports this site, but no HX-40 vendor (officially), I hear good things about the HX-40 from those that run it. Only real negative at this point I've heard about is that it is not a kitted any DYIer install with 24/7 support.

I do have some reservations for long term however, I hope that in the lower Hp load with the 6.5 than what it saw on the peaked & tweaked Cummins where some OEM HX's grenaded; the CKO HX-40 has OEM longevity and some yet to be experienced issue is not in hiding in a knockoff copy HX .

But the really amusing thing that the same criteria some applied to the ATT being a CKO of the Mitsubishi TDO-7 22A as being a bad and risky thing, are now head over heels in love/support of a HX-40 CKO, my concern there is durability of CKO 40, and the aftermarket customer support of a CKO if something at point of origin (China) changes that would impact the turbos down the road.

Kudos/props to Slim Shady/ATT when the design changed at point of origin that enlarged the housing wholly at mfrs discretion without consulting Slim that he recalled all suspect turbos and replaced them with the correct as designed housings.

Will the CKO HX-40 make good on that we don't know yet 1st time a CKO_40 install goes bad, I do wonder if that failure will receive the same negative "fanfare" the ATT did when it had some issues; also do we have a 4 year old/high mileage CKO HX-40 out there yet, 4 years and counting on my original ATT 150K in my truck, and 2 years 50K miles on my 2nd one in my Burb I'm most pleased with my choice of ATT.
 
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