Boosting Power: Upgrading A 6.5 Detroit Diesel With A Holset Hx35 Turbo!

[@happycamper137]

No matter what else..... the 6.5 is the best sounding diesel EVER!!!

[@FreedomFarmsMo]

I wouldn't go that far I still think my Duramax sounds better but it's still a cool truck

[@matthewramsey6835]

Cool to see someone still messing with these trucks. Planning to do a hx35 soon myself.

[@FreedomFarmsMo]

I use it as a daily and light towing around our farm 10,000 lbs or so. Anything more than that I use my Duramax

[@Milkman3572000]

You are livin it! An adult playing with his toys! When I saw your video.. I thought to myself.. WHY would anyone mess with perfection? Because You CAN! I am a huge fanboy of these 6.5s. and 1911s. Older is better in my opinion.

[@FreedomFarmsMo]

I really enjoy it honestly. Spoiler alert most of stuff is older. Our tractors are 40 and 48 years old. Our combine is 40 years old too. I actually have a us army issued 1911 too😁 I'm pretty blessed

[@JREACHER1954]

Nice. Yeah, the factory style lift pumps leave a lot to be desired. IIRC the EP158 (93 year model) has the best numbers. I swapped out to a Carter 4601HP and fuel pressures on my 94 range between 9-11+ psi, depending on throttle. Still run the factory GM-4 turbo with vacuum controlled wastegate. Kept it that way as I feel I can achieve the best fuel economy and I don't tow enough to warrant a turbo upgrade.

[@FreedomFarmsMo]

The Carter 4601HP is what I purchased. It should be here early next week. I also ordered a tune from quad Star too. The hx35 really makes it a whole new truck even without a tune. It has also gotten about 1-2mpg better since the turbo swap as well. Factory turbo we averaged 18-19, now we are consistently 20+ mpg. We use ours for towing but nothing heavy. We use our Duramax for anything more than 10,000lbs.

[@milesj6064]

Nice job on the upgrade. I used to have a 98 K1500 with the 6.5, I upgraded the center section of my turbo with the wicked wheel from Heath diesel, and also upgraded my lift pump, and relocated the PMD and upgraded the battery wiring on the truck. I enjoyed that truck and I love listening to your truck something about the sound of the 6.5 even compared to the duramax. Keep up the good work, and I will be checking out more of your videos.

[@FreedomFarmsMo]

Thanks you. I enjoy, I still love my Duramax too but the 6.5 is a good truck. I have done all the same upgrades as you plus recently got a tune from quadstar too

[@ambikesandboards]

You can swap in a 1993 stock lift pump and it gives a lot better psi than the newer models like 9-11psi at idle. I got mine from o reillys bc it has lifetime warranty and I had problems with ac delco brand i got from rockauto. The oreillys lift pump is VERY good. Always keep a spare onboard though

[@FreedomFarmsMo]

I swapped in a carter pump. Makes 14psi at idle and maintains through the rpm range. Thanks for the idea though

[@ambikesandboards]

@@FreedomFarmsMo good to know about the carter. thx for sharing

[@FreedomFarmsMo]

@ambikesandboards you're welcome

[@Dmdmvt]

Man we need to start a community bros I got a 6.5 too

[@FreedomFarmsMo]

There are a few groups on Facebook for them

[@coltonleavitt3660]

I got a 6.5 to

[@vvvv-lu8zi]

Im between that 6.5 a lq4.....

[@jj629ful]

I have a 6.5 turbo diesel looking to upgrade the old turbo and will a gas turbo work?

[@FreedomFarmsMo]

Probably not well. Diesel and gas engines flow air in very different ways. For instance a gas engine has a throttle blade to control air to control rpm. A diesel uses the fuel to control rpm and there is not a throttle blade at all.

[@michaelotten6334]

I need that whistle! Liked and subscribed.

[@FreedomFarmsMo]

It is great, and really runs way better too

[@JuniorJunior-g4c]

I have a 6.2 diesel with a hx35, I turned the pump up a 1/4 on the fuel.. but i only run 4 lbs average ,and maybe 8 full throtlle .. Why dont i have the boost numbers you and others have ,or what can i do to get more boost lbs . Thanks , great video!!!

[@FreedomFarmsMo]

The hx35 is likely in need of the 12cm exhaust housing and you likely have the 15cm exhaust housing. Turbo speeds are based on a few variables. Exhaust velocity/flow, fueling, timing, and heat loss. The 6.2 may just not have the fueling capacity either, injectors/injection pump may need upgraded to 6.5 versions?

[@nasersamara3836]

this engine have to install inter cooler like i do it be crazy power not to biger the turbo

[@FreedomFarmsMo]

A more efficient turbo is a far better power gain

[@2insane484]

Thanks for sharing! Did you ever consider a super 60?

[@FreedomFarmsMo]

I did consider one but for $1300 less I achieved what I was looking for. The 6.5 will never be able to compete with a modern diesel and I rarely use it to haul more than 10k lbs. Anything more than that we use our Duramax

[@christopherwilson7698]

Wow that fuel pressure was making me 😢, Thank you for the video excellent info and explanation I think 6.5 guys just love underdogs lol. Good luck with her🍀 and keep the videos coming, oh also what do you think about a 5’ exhaust waste of time ?and adding intercooler..???

[@FreedomFarmsMo]

I think an intercooler is absolutely necessary otherwise if you're just forcing hot air in it won't make much power compared to the same amount of air at a cooler temperature. The 5-in exhaust would be a waste of time I only have a 4 in exhaust on my Duramax. My Duramax makes 653 wheel horsepower and 1601 ft lbs of torque with 4" downpipe and exhaust. Definitely wouldn't need a 5" on a 6.5

[@floww812]

Debating on the 35 vs 40 and 54 and 60

[@FreedomFarmsMo]

The HX35 made a big difference on my truck. It was night and day from stock turbo to the HX35. And that is no change except the tune. Ran the same boost levels and everything else factory. Now I have a tune from quadstar and it is even better yet!

[@JB-iq3sy]

Did the hx35 and quadstar tune have an affect on fuel mileage at all?

[@FreedomFarmsMo]

Fuel economy with hx35 and factory tune gained about 1.5 mpg and took me to 17.5 @75 mph with 4.10 and nv4500. The tune from quadstar got me up to 18.3 mpg @ 75mph. Those are full tanks highway only.

[@herschelmajors6237]

Sounds nice

[@FreedomFarmsMo]

Thank you

[@glocktopi1796]

So can I put a hx35 without any other supporting mods or will I break something

[@FreedomFarmsMo]

In my opinion like I mention in the video. The factory turbo was the cause of head gasket issue because of the drive pressure restriction. The hx35 is much safer. I run 15 lbs of boost with no issue

[@floww812]

I really want to go wvo , but alot of kits been discontinued on these. Are you getting better mpg's with the hx35 swap?

[@FreedomFarmsMo]

Mpg went up less than 2 mpg but the power is substantially better

[@Jean_1999]

Is the HX35 not making too much boost when you first start it? Im sure if I install this Turbo on my stock Truck its gonna defuel. Would be cool if there was some sort of Turbomaster for the HX35. Because putting together my own turbomaster is not really something Im good at😅

[@FreedomFarmsMo]

You can't run it with eh factory waste gate that comes on the hx35 because of the turbo orientation. Watch the full video and you can see why it won't work and how I made my turbo master work on it.

[@ThirteenTwentyRepair]

I’ve become a non believer in the repeated myths of the 6.5. I run an HX35 average 7-15lbs and peak at 22lbs when I’m balls to the wall passing someone at 80mph. 230,000 original miles, no studs, commute an hour each way to work daily and tow between 4-7,000 lbs. egt’s rarely hit 800 and usually live between 4-700. Back pressure is what kills a head gasket and I’m making less back pressure at 22lbs with the HX35 4” straight pipe, then I was on the GM4 at 15lbs.

[@FreedomFarmsMo]

I agree that the turbos caused a lot of issues that plagued the 6.5. I don't push mine as high I only run 12 psi. It's done well for me so far. It does get warm pulling long hills with a trailer. Generally we are pulling between 5-12k trailer weight.

[@100pyatt]

FACTS

[@williamwheaton8117]

Max EGT of 800 degrees? Are you running an intercooler? Or just upgraded water pump, fan and fan clutch?

[@FreedomFarmsMo]

@williamwheaton8117 the only thing that will help egts is an intercooler a better exhaust housing on a turbo or water methanol injection. A water pump or cooling fan or anything else of that nature won't do anything for your exhaust gas temperatures

[@joseesparza2364]

How do you think an hy35 would fare on a 6.5?

[@FreedomFarmsMo]

I would say about the same but I'm not sure and don't know anything about the hy35

[@terryburgettburgett965]

Sarge the hot rodder

[@FreedomFarmsMo]

Absolutely 😁

[@terryburgettburgett965]

Hey Sarge how are you

[@FreedomFarmsMo]

Doing well Terry, hope you are too!

[@zoemiagab]

did you re-stud your heads? The 6.5 is not built to withstand over 10 or 11 psi......

[@FreedomFarmsMo]

I did not stud the heads. The 65 is capable of 15 psi safely with an aftermarket turbo. The reason it would blow head gaskets above 10 psi was the factory turbo had a 2:1 drive ratio so it took twice the drive pressure to create 10 lb of boost meaning if there's 10 lb of boost in the intake there was 20 lb of resistance on the exhaust. So you had two forces fighting with each other and they found a weak point which was typically the head gaskets

[@tylermayes9830]

Been running 20lbs for over 3 years on an H1C, just upgraded to an HX. These engines are stout if you're not overworking a stock turbo setup, drive pressure is what kills these, not boost

[@terryburgettburgett965]

Backflow kills horsepower even on a naturally asperated motor

[@FreedomFarmsMo]

It absolutely does

[@Moose400ex]

lol My god those motors were complete turds. Clunkers and to think that 6.5L and fords 6.9L IDI motor were the only competition that the Cummins 5.9L 12valve VE and p7100 notes had! That hx35 is capable of soooo much more lol. That clunky 6.5 doesn’t have enough sack to get full boost out of that hx35. You really need a FASS system lift pump dude. That’s not enough fuel pressure or flow. When you started saying… ‘it’s time for a…’ I wanted to fill in the blank with ‘Cummins 12 valve swap’. It’s cool to see some of those old detroits still running these days, most all blew the head gaskets. They weren’t very good motors, noisy, clunky, low on power, weren’t very efficient motors. Not compared to a Cummins. The problem was They didn’t have enough bolts holding the heads on and clamping force, so it caused them to spit head gaskets out. I mean i guess you could put head ARP head studs and o ring it but I don’t know why you would want to put any time, money or machine shop time to o ring the heads. It’s just be kicking a dead horse. Take that clunkey oily nasty Detroit thing out of there and swap in a 12 valve Cummins if you were going to put any kind of money at it at all. A 12 valve Cummins will fit puurrrrfeclty in there and power that thing puurrrfectly. One with the good 215hp p7100 pump would be the best, but you could defiantly use one of the lower hp ones depending on what you able to find. The 215hp’s are getting harder and harder to find all tho I guess there is a Chinese company that’s reproducing them and knocked off the Bosch castings. lol finally china uses their infringement on something good! Heck even one of the first generation Bosch VE rotary pump 22 valves would be more than plenty for that lead sled. Believe it or not the VE injection pumps are capable of 600-700hp. They can make huge power. They’re reliable injection pumps, they are easy to tune, and will eat any type of waste oil or waste veggie oil, motor oil, or trans fluid or hydronic oil if you were wanting to run that stuff mixed and diluted down with diesel! Parts are cheap for a 12v, they are easy to work on, they are simple, and reliable and make tons and tons of low end torque! A 12v would drag that old clunky 6.5 backwards around town all day! I’ve done several swaps over the years. Swapped a 12v be rotary pump motor into my buddies 1 ton square body suburban on 40” swampers. My buddies ‘97 Chevy half ton had a p pumped 12 valve motor in it. There just all around good fitting motors, they get killer fuel Milage, mid-high 20’s all day long, towing a trailer!!!they’ll fit in anything! There’s companies out there that offer swamp/ conversion kits, motor mounts kits, and everything you need to swap one into a Chevy square body, fords, ford OBS, Fummins swap! Nothing better than a ford with a Cummins. A cummins swap is a lot easier than you might think, depending on what choice of transmission you choose. The best thing would be to use a 5 or 6 speed manual trans, like a nv4500. That OE Chevy trans is gunna get eatin up by the power and torque of a Cummins, it won’t last long lol. Cummins 12/24 valve swap the world! Haha.

[@FreedomFarmsMo]

Cummins? 😂 That's cute.....the 6.5 had a head gasket issue due to the drive pressure of the factory gm turbo. The factory turbos had a 2 to 1 drive pressure as mentioned in this video. That was the purpose of changing to a different turbo. Secondly a 6.5 does get good fuel mileage, I average 20-22 mpg driving to work and back every day 70% hwy and 30% in town driving. Lastly this truck has an nv4500 and there are minimal differences mainly being input shaft spline count, bell housing, and output shaft spline count in the nv4500 that Chevy and Dodge both shared in those years. If I were to swap it it wouldn't be a Cummins. It would be a Duramax. The Cummins isn't a bad engine but it is far from superior anymore. In 2001 the Duramax changed the game and Chevy had a direct injection diesel like Cummins and power stroke and leveled the playing field since they were using similar technologies. Also no diesel pulling 10k+ is getting 20+ mpg. When we are pulling trailers we are never pulling less than 8500 lbs as our 32' hydraulic dovetail gooseneck is 8500 lbs empty. Glad you like your Cummins, but you won't be seeing one around here.