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Turbo Sing and our beloved 6.5's

dbrannon79

dbrannon79

I'm getting there!
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Seguin, TX
I had a question on all the different turbo options out there including the wicked wheel as an option for our trucks. I thought I'd ask what y'alls opinions were and how each turbo acted under different conditions.

I know I am not looking to upgrade any time soon due to the need for a replacement engine, though if I run across something in my price range or used, I might be intrigued to try it. but what I am looking to do is be able to hear it sing as I cruise at low speeds through town, taking off lightly from traffic stops and such. I love to hear the turbo sing but with mine, the only time I can hear it is when I have the passenger windows down and I'm driving past buildings on the passenger side where the sound echoes back from the exhaust. Other than that I can barley hear it when the engine loads up.

Reading and talking to some of you all here, I learned that the ATT only spools up around 2000 rpm and under load which is probably one of the best towing turbos out there, but for me, a person who will probably never tow anything heavy or rarely tow anything at all idk if that is for me. what I would like to do is find something that I can keep it within stock boost pressures and hear it at low rpms, also hoping that the PCM can still control the boost with the actuator and vacuum solenoid. I'm not looking to get more power or make more boost, just hear the sing :)

I have been looking how the HX35 is and how it reacts at low rpm on our engines, but I really can't find much info in that area other than it supposedly does better than stock which really doesn't tell me anything. Also read where other's have said the WW will make more noise but not much over stock.

Lately I have been seeing a lot of talk about the ebay ones on the FB groups praising them but I can see that most that post them are youngsters that just wanna make a power house out of these engines. knowing those from fleabay can explode and destroy and engine when put under a load, it makes me very hesitant and want to steer clear from them.

If this maybe explains it better, it's just for show, kinda like those idots do on their rice burners that no one likes to hear, but the turbo whistle on a big truck has always been music to my ears lol !
 
I can't help you on that.. although I do definitely love to hear the spool😁...I cut out my exhaust, eliminating the soot trap and such which allows me to hear it more. But that's cause here you don't have to pass emissions with a older diesel...also hear it better with more air flow ..not sure what air box your using... Honestly a turbo is a expensive part to change for nothing more than more spool... although can't say I wouldn't do it if I had the cash 😉
 
I hear ya on that, the less $$ the better. I still have the OEM flat panel filter (snorkel removed from fender) 3" downpipe to straight 4" diamond eye exhaust kit with muffler and 4" to 6" tip on the tail.

I did hear the turbo better when I had that spectre cone style open air filter, but I got rid of that since I was pulling in hot air under the hood. but even then the spool sing wasn't all that! I have had thoughts of getting a washable air filter in the OE box but after talking to some of the guys here and looking at filtration reviews, I kinda veered away from that in fear of dusting the engine.
 
Transmission and gearing have a lot to do with the turbo that is right for you. A 12cm hx35 will spool immediately with most setups. I can't help you with the whistle. I only hear mine at 3 and 7psi (not loud and very brief). However, ANY turbo with a bigger exhaust housing will reduce drive pressure and make your engine happier! Just don't go too big. Variable vane turbos definitely sing louder.
 
I always thought the GMx turbos would benefit having a larger exhaust housing / larger exhaust impeller. I wouldn't mind getting my hands on a used HX35 from an older Dodge 12 valve to try without spending a bunch of $$, but I am not certain that they have a vacuum actuator on them. those all you have to do is remove the beauty ring in the intake housing to make some noise lol

now finding a pick a part junk yard with a diesel engine is a whole other task around here!
 
dbrannon79 said:
I have not heard of that mod. is that something done to the stock turbo or a whole other thing?
Click to expand...

I wouldn't waste the money on doing it to a stock turbo. But plenty of aftermarket turbo companies offer it for $300-$400. All it does is make the turbo whistle ALOT louder. There is no performance to gain with it. But is sounds awesome!
 
dbrannon79 said:
I always thought the GMx turbos would benefit having a larger exhaust housing / larger exhaust impeller. I wouldn't mind getting my hands on a used HX35 from an older Dodge 12 valve to try without spending a bunch of $$, but I am not certain that they have a vacuum actuator on them. those all you have to do is remove the beauty ring in the intake housing to make some noise lol

now finding a pick a part junk yard with a diesel engine is a whole other task around here!
Click to expand...

I agree that the stock GM-x series turbos are not worth messing with. I have plenty of used Holsets setting around and could set you up with one for your truck. An hx40 is a great choice for a one and done turbo on these engines.
 
dieselfuelonly said:
I agree that the stock GM-x series turbos are not worth messing with. I have plenty of used Holsets setting around and could set you up with one for your truck. An hx40 is a great choice for a one and done turbo on these engines.
Click to expand...
how are the HX40's compared to the 35's? I have no experience messing with them other than what's stock on my truck! I'm sure there is a super performance gain with ether one, does one spool better than the other at lower rpm, or have a way to keep boost calmed so I don't go boom lol

sorry for all the questions, I am very interested.
 
I can't say I have direct experience with either, although I do have a 35/40 hybrid sitting on the table waiting for me to finish the charge air cooler. This is my basic understanding of the main differences, folks with actual experience running one please correct me if I'm wrong...

the 35 is smaller than the 40. Which means it can spool up quicker at lower rpm. But due to it's smaller size it has higher EGTs at higher boost levels compared to the 40.

Not to say a 40 can't be made to spool up quickly too. However, the 40 is a big step up from stock, and given what you're looking for and considering the health of your engine, I think the 40 would be overkill.

If you did lots of open highway cruising, the 40 would certainly be a good option. But from what I read you're looking for a little more giddyup in stop and start traffic, which to me the 35 is better suited for.

I see you already have a boost gauge, which will be really helpful. If you want to run more boost than stock you'll have to install a boost fooler or have the ecm tuned to allow higher boost without setting a code or going into limp mode.
 
I was thinking the same thing, the 35 would be bigger compared to stock, 40 would be even bigger! I don't think I'll need a monster even when I do find a replacement block. I would like to see a little more giddyup for when I need it plus the idea of the turbo whistle as I'm just creeping through a parking lot as others see my old gelopy wondering what's he got under the hood lol
 
It’s about your use- not big/ bigger/ biggest.
If you plan to keep it 2500 rpm and don’t want a bigger power bump- then hx35.
The 35 still doesn’t push enough air to use up all the available fuel above2200 rpm.
If you want that power all the way up through the 3,000 range- then 35/40 hybrid.


Pushing way more power and wanting it throughout then 40
 
@Will L. what's the size of the 35 compared to stock GM8? just between the two is there a noticable difference other than the whistle? I'd like to keep my rpm's lower, heck, if the 35 will do good at lower rpm and give some moderate power increase I may want to look into changing the rear end gears to a lower set for better fuel mileage on the highway. the more economical I can make it, the better with these fuel prices rising! just did my fuel mileage today and got 13.5 mpg on mixed driving.
 
The GM series turbos are said to have about a 9cm (squared) exhaust housing, whereas the standard hx35 has a 12. Also available is a 14cm (what I have). Lower drive pressure at similar boost is the big advantage of the Holset over the factory BorgWarner. Running a gm-1 thru -8 at higher boost is a good way to lift the heads off of the block (I've done it).

Real world, your IAT will come down a little, and your engine will run "freer" and be less stressed.
 
In my opinion pretty much anything is an upgrade over the factory turbo. I bought my first 6.5 before I really knew much of anything about diesels. Previous owner claimed to be a diesel mechanic and he had installed boost and pyrometer gauges. Again didn't really know it at the time but the dude had installed a homemade turbo master and essentially welded the wastegate shut. I'll find a pic of it for y'alls entertainment. Between the pyrometer breaking early on and not knowing it was a problem to be running the stock turbo at 15 psi, the engine seized less than a year after I bought the truck. So yeah, get rid of factory turbo and install a pyrometer.

Since @dbrannon79's engine has blow by and 300k on it, I think the 35 would be a great option running no more than 12 pounds of boost. Don't want to force too much air into a tired engine. If the engine wasn't a bit spanked maybe the 35/40 would be a good option, but with head bolts, no CAC and no way to monitor EGT or IAT you'd be playing with fire. Even though I have a studded p400 I haven't thrown on my 35/40 with the 14cm2 housing because I was advised not to do so until an intercooler/CAC was in place. I've already had 2 6.5s grenade on me and I'm not looking for a third!
 
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