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Newest hmmwv- NXT 360

Will L.

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Thread starter #4
So -p400, electronic ip, hvlp turbo, 6L85E trans. And some 20” wheels I actually like.

Wondering how they did the ctis because you can’t see air lines from center going out like old style. The only problem with the old ctis system was crappy fittings they used.

Now about the price tag...
 

Will L.

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Hmmwvs never had an electronic ip before. I read something about emp proofed electronic injection.

But this also wouldn’t be the first bit of misinformation out on updated hmmwvs.

Last I knew was a db4 going onto p400’s, but if them boneheads would learn from long term users that know it instead of asking military mechanics that got their training from the people that later ask what is best causing cyclic theories- they would have stuck to the db2s that are proven most reliable, longest life, and most power available. SMH. Sometimes wish I had stayed in the loop with the 6.5 decision makers.

Imagine if they were to have p400 heads done in a cnc with Chris’s flow capability and coatings. Then spent some time on a VVT like the dmax like the 2 brothers did. Then imagine the db2 being built to performance specs like some of the real pump builders could do like ol Scott from J&S.
Nay sayers that stuff would never happen, but I remember when coated crankshafts were never gonna happen. It isn’t like they are tryin to produce the golume GM did. Add a couple machines and few more people in production line and add maybe 3 days to each build for another 100 hp and 200 torque, and get more engine cooling and longer, more reliable life to boot.
 

Will L.

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222DF607-E819-4EAD-BC51-EAEB5E688DDF.jpeg

They made changes to the front end- original was newr flat at the blue arrow. The extended front grille, which has since been changed to this version is slanted enough that maybe it changed the aerodynamics of it that this is a good set up. Really hope they were smart enough to have the coolant heated up like we did and run the fan like we did all inside a wind tunnel.

The best design that worked on the old hood had the front edge just past flush with the front end, not back or tapered like the green arrow points now.

Also the height of it is much lower, maybe why they tried opening up the front and tapering the sides so it could pull air in easier at the 30-50 mph range. The best height was roughly 1.5” high measuring vertical from the rear of the top grille (closest part open newrest the wind shield). Then the top piece was parallel to the ground, not tapered to match body at all, so it would catch 100% of the air to the top of the scoop and create a higher pressure at the back of the scoop on he inside. It also allowed plent of air to be drawn in when zero head wind is present.

Side walls were vertical. It looks like the rear wall is the same angle as ours.

The red arrow shows the basic airflow that occurs. Up the hood, up the windshield (yes in rain at higher speeds the water drops goes straight up in many places on the windshield). The air going over the roof creates a pocket and forces the air bouncing upward off the windshield foreward towards the upper radiator grille. (Just like riding in the bed of a pickup close to the cab- how the wind goes exactly backwards of what most people think it would do). When the headwinds speed gets up to modern freeway speeds (above 55) there is a literal wall of wind blocking air from coming into the top grille. The faster you go, the bigger the air blockage gets. So the top plate of the hood scoop stops the air pocket from getting to the opening. That allows the incoming air to be drawn into the stack.

An interesting thing is most of the air coming in keeping it alive is from the front grille. But with the top grille wide open, a lot of the incoming air that goes through the front grille goes over the radiator and up out the top of the top grille. It just skips over the radiator like you imagine it does over a sloped hood.

That is also part of how the scoop top coming all the way foreward helped. By creating no exit point, all the incoming air from the front grille is forced through the lower (front) half of the stack. Then the air that got trapped by the scoop gets shoved to the back of the scoop, and by having the top flat (we tried angles of corse) that air curled downward of the back angled plate through the top (rear) of the radiator. That part was actually key, because getting the most cooling air tk go through the hottest part of the radiator made the best temperature differential.

I know when Bill Heath designed his scoop for Hummers He told me it was later redesigned by the hummer parts sales parter he was working with for better aesthetics. He said the testing showed his original worked about twice as good. When he described it to me dimensionally, it made sense. This scoop is similar to the redesigned one that He worked on, and since He said it was about half the performance... well... I am not convinced they actually put this hmmwv in a wind tunnel, compensating for engine fan, front tire air disturbance, etc.

I hope they did. I am guessing this new one is also using a gfd with the larger radiator and 24” (ish) fan against the radiator like it should be. Also hope they corrected the radiator core pattern away from the 1920 design of inline cores for the staggerd and dimpled ones.

It would be nice to see this in person and even talk with one or some of the folks that designed this. For interest in learning and incase there is anything I can share. Then also to put a bug in their ear about selling parts to us average folk, and congrats to the individuals that took what imo is a good platform and stepping up its game.
Anytime a super capable off road, upArmoured rig can weigh over 15,000 lbs, and do 100 mph- oh yeah!
 

Dullahan

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#12
Great info, thanks! This part caught me by surprise:
View attachment 53140
An interesting thing is most of the air coming in keeping it alive is from the front grille. But with the top grille wide open, a lot of the incoming air that goes through the front grille goes over the radiator and up out the top of the top grille.
It makes me wonder, if the upper grille could be closed off at speed, with a Venetian blind type of setup rather than fixed grille bars, would it make a noticeable difference?

It also seems most scoops, unless the back end were horribly designed, would block the high pressure air at the base of the windshield (red arrow), and provide at least a little improvement. The remaining performance would be from a combination of good flow through the scoop into the stack, and ram air effect - the latter working at it's best like you had it, with the front of the scoop even with the front of the hood (no real boundary layer issues). Am I on the right track or barking up the wrong tree?
 

Will L.

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Thread starter #13
We tried shutters to stop top wind disturbance and trap more air from front. Didn’t work. Not enough area to allow needed cfm. Also we were trying to avoid things that fail, and moving parts fail.

Blocking a little of the back helps, but the faster you go, or more headwind present, the farther foreward the blockage becomes. I don’t remember exact numbers, but something like 55 mph the reversed flow front was in front 1” from rear of shroud. At 60-5”, at 65-8” at 70-12”, etc. it continued until there is a slip stream that covers the entire top grille. Cfm is increased proportional to speed, provided it gets throalugh the radiator. But at lower speeds there has to be a large enough opening to allow enough air in. So really low pro units will restrict to much.


Some people say, it’s not a race car, just do 55 max- what they engineered it for. To me-what if 2 possibilities:
1. Headwind. Last 3 days we been dealing with 25 mph winds. So overheating freeway speed heading southbound would be 35 mph.
2. I’ve been shot and done some shootin. My preference is not gettin shot for some reason- haha. Sometimes getting out of the area is a better option. Who the hell wants to think, “Oh, I better not drive over 55? Maybe they will quit with the shootin cuz they know 55mph is all this was designed for.” Or the worse ever is “Don’t worry guys, we will be there to give help when we can, but you know we can’t do 60 mph or we might overheat.”
Slow military vehicles is the dumbest ass thing I ever seen. Big part of why I like that they got this heavy thing up to speed.

Anyways.. this new front end will flow air very different, wait and see I guess. The difference of the more effective fan they will be running will make up for a lot.

You’ve no signature filled out, do you own a hummer or hmmwv?

Hummers/hmmwv have a wierd problem of overheating that shows the aerodynamics being the main issue. Hummers never overheat in city traffic, regardless of work load.
You can take the fan off a 6,000 lbs pickup truck, get on the hiway and cruise at 60 mph and it will jot overheat. Until you get to the offramp, then be mighty careful. A hummer without a fan is doomed the faster the speed the worse it is. Myself and another hummer owner did this (my old gm block not my optimizer) in verifying the problem.
 

Dullahan

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#14
2. I’ve been shot and done some shootin. My preference is not gettin shot for some reason- haha.
My sincerest thanks for putting it all on the line so the rest of us can do cool stuff like talk about the idiosyncrasies of cooling systems without fearing for our lives, livelihoods or freedoms.

Mine's a Hummer - I considered a Humvee because I liked the waterproof electrical system and the ability to add the fording kit, but ease of adding 12v accessories and A/C won me over. :)

Another thing jumped out at me on the NXT 360 - what's the story on the hvlp turbo? I'm guessing high volume low pressure, but do we know if it cures the 6.5's asthma? Do we know if it's a bolt-on replacement for a gm6 or gm7?
 

Will L.

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Thread starter #15
OMG it makes all the difference to the 6.5!
ATT, hx40, hx35/40 hybrid, are good options. But no one makes a kit yet for the Hummer. @Burning oil Leroy started working on one, but has half of Pittsburg's irons in the fire- Any news on that Leroy?

The closest thing has been the s300/s400 hybrid that was offered by Peninsular Diesel, which is now owned by John of Unique Diesel. Maybe see if he has any info on it?
 
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