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98 Chevy 6.5 what new turbo setup should I use
- Thread starter 1998chev65td
- Start date
My MPG improved as I noted in the long install thread as it quit smoking so bad and burned more fuel on take off, but, My build was a unique NA 6.2 with the small NA precups and the ATT/BD Spool Valve dropped on. The small precups held me back for burning more fuel than the GM3 could at it's 14 PSI redline boost. Your 6.5 Turbo precups are bigger so YMMV.
Husker6.5
135' diagonal 16:9HD, 25KW sound!
Yo Mama May what?
boatist
New Member
I just went from ATT to HX40Wii. I kept my ATT KOJO tune and my crossover and downpipe are wrapped. Loss of boost between shifts and having the power come on above 2000 were my main reasons for the swap. ATT pulls like hell from 2400 to 3500 and will even make a little boost at 1500. Its too early too call which I like better on my truck but the added whistle with the CKO (subtle but noticeable) makes me grin. Just my two pesos.
6.5L
Old Iron Runner
The MT with an ATT was great, although it had it's Achilles heal; the 3rd-4th rpm drop. It takes a lot to spool the ATT back up after that large of an rpm drop. Unloaded it was fine, and mileage was around 20mpg. So pretty good. Cruising boost was around 3psi at 2500rpm light throttle. The BD-Spool Valve I used immensely helped the spool and rpm drop. It really woke it up in the bottom and once the valve opened at the top end, it could carry it the distance. Think mechanical VGT. Cruising boost with the valve as I set it up was around 5psi light throttle. Mileage was around 19mpg. There wasnt really a lot of downfalls to the valve. And the sound, really can't be described. Only "unholy". It is quite an experience. The only reason I changed turbos was because I like trying different things and got a good deal on a HX35. Then it was an HX35/40 hybrid, and now I'm running a billet HX40 with a 14cm housing. They've all had their ups and downs. To be completely honest, I am probably the happiest with my HX40 as far as all around performance with my MT, but I'd love to get the ATT back on the custom manifolds and see how it does after hitting it with the WMI, just for fun. Hopefully this weekend I can pull the pan and see what happened and do some investigating. I've already got a large list planned out for Leroy.
Will L.
Well-Known Member
Quick spool- or anypart of the turbo affecting mileage: the more air flow (not just boost) and the sooner you can add it as well as keep it all the way up the rpm band, the more it helps create power. The more power you have available at lower throttle position you can move the truck wigh less fuel down the road. The hard part is not "enjoying" the new found power too often. So instead of towing a trailer up the hiway at 90% throttle, you can do it at 50%. Instead of W.O.T. Getting up to speed from a stop light, its only 50% throttle. That helps mpg a lot.
@6.5L I think we all have a list for Leroy, Most of us just can't get the bank account to back it. I know thats my problem. Haha
I really enjoy seeing the different turbos you run and posting the details.
I'm kinda surprised i havent seen you guys jump into compound turbos with a waste gate dumping from the little gm into the ATT or something big like that. More expense, but already having the factory as the small, and upgrading to the bigger one, then later when the playing starts it is just plumbing, a wastegate, and an extra boost gauge for testing.
For me just fitting the hx40 or ATT is a challenge, but to add both would be hard. Knowing how they do on a friends 7.3 and a big pump has made me consider turbo on the roof, no joke. I just can't pull that trigger...
So something to learn by the newbys here is when upgrading turbos, if you know you will not tinker with your rig for fun or getting the most out of it, sell the old parts to offset the new ones. But if you ever get to playing around with stuff, shelf the old turbos for later projects and parts trades.
@6.5L I think we all have a list for Leroy, Most of us just can't get the bank account to back it. I know thats my problem. Haha
I really enjoy seeing the different turbos you run and posting the details.
I'm kinda surprised i havent seen you guys jump into compound turbos with a waste gate dumping from the little gm into the ATT or something big like that. More expense, but already having the factory as the small, and upgrading to the bigger one, then later when the playing starts it is just plumbing, a wastegate, and an extra boost gauge for testing.
For me just fitting the hx40 or ATT is a challenge, but to add both would be hard. Knowing how they do on a friends 7.3 and a big pump has made me consider turbo on the roof, no joke. I just can't pull that trigger...
So something to learn by the newbys here is when upgrading turbos, if you know you will not tinker with your rig for fun or getting the most out of it, sell the old parts to offset the new ones. But if you ever get to playing around with stuff, shelf the old turbos for later projects and parts trades.
6.5L
Old Iron Runner
Well, with all things considered, my folks let me borrow an old little Ranger they had while mine is toast. I think I am going to buy it off them and retire the six nickle to "project" status so I can go all out on it. Which means I can finally get my intercooler going, along with compounds and a hoodstack, and my prototype pump. Which were my goals for a while. Just couldn't do it with my DD. And I don't have the funds either, but I do have an open credit card lol
They are both great turbo's over the GMx crap. At the end of the day I need everything the top end has for power due to derating from extreme outside temps, low humidity, grades all over the place here... Love to see others do the same comparison and try other turbo's as well. I feel the HX40II gets you get more boost at the expense of more backpressure and detailed what I found (nearly same HP and TQ on the dyno) running both here: http://www.thetruckstop.us/forum/threads/att-run-vs-hx40ii.38950/
After driving the MT Dodge I have with the NV5600 and @6.5L comments IMO @Hill Top would benefit from splitting the 3-4 shift. 3, 3 with GV on, 4th GV off, then 4th GV on... make sure you address the 5th gear nut issue when you are adding the GV unit. The NV5600 is a heavy slowshifting SOB that's cranky when cold so I don't recommend that. (It also sheers down even AMSOIL quick!) G56 maybe. Both have the extra gear to help that 3-4 RPM difference over the NV4500. The GV addresses it with parts on hand looks like...
At the end of the day the 5.9 MT gets me nearly 20MPG around town in the long bed crew cab as long as the AC is OFF. The auto in Patch gets 10. 14 on a good day freeway. The 5.9 nearly became the first 6.2 dropped in a Dodge 3500 due to engine replacement cost.
Will L.
Well-Known Member
6.5L
Old Iron Runner
HAHAHAHA
boatist
New Member
LOL. I think CUMMINS owners everywhere would have a heart attack.
6.5L
Old Iron Runner
For fun, I posted on a Cum Dumpster forum on facebook for fun that I was going to swap a 6.5L I had in place of my blown 12valve 5.9L "because I had the spare motor, cheap parts, and wanted something reliable". OMFG the world blew a top lol It was the funniest shit ever.