Engine RPM basics

["Mad Max"]

Well, here's the assembled mock-up for the driveline - just to see if it all actually bolts up - it does.



#ad




In the end, it'll be NV4500 + NP205 + GV overdrive + 4. 10's + 35" tire (285-70/R19. 5) = 1800 rpm @ 80 mph. Sweet.



- M2

 

[JLEONARD]

I'm agreeing with Cerb and thinking you would benefit by having a conversation with the guys from HTT about a turbo/turbo mod choice for your circumstance.

 

[Don Tanklage]

If you back the high idle stop out... ... ..... about 3600.

3600 in neutral with the stock spring and high idle backed out, okay...



thank you



hummmm



how high will it rev with a load on it? (with the stock gov spring and the high idle backed out)



thanks in advance, don

 

["Mad Max"]

Was talking with Mark up at PDR about turbos, and I think what I'll be doing is a PDR HX-35/16, PODs, 3400 spring, and a PDR fuel cone, plus all the usual pump and timing upgrades.



On top of that I'll be running an ATS intake ram and exhaust manifold, and a Snow water/meth kit. Boost aught to be in the 35 psi range, and I'll set up the meth to kick in around 28 psi. That's about as far as I want to go without having to crack open the engine (except for 60lb exhaust springs for the e-brake, and to kill the KDP).



Thought about a 14cm collar, especially at my altitude (6800 feet), but with the weight (about 8000 lbs unloaded) and primary use of towing, we want to keep the exhaust decently open to get the heat out. The turbo will spool decently quick, but spool-up isn't as important as heat removal in gear under load. The meth will help significantly for the really heavy stuff, and that's also where splitting gears will be a pretty nice perk, especially in 3rd and 4th gear. The hills out here (Rocky Mountains) are pretty steep, so having the splitter will be sweet. Then, depending on the power-to-weight feel, I can either overdrive 5th, or leave it off and let the engine twist a bit. Should be the best of both worlds, all under full manual control.



- M2

 

[bgilbert]

Sam I thought you had a PDR35 on your old engine? If you still had it, I'd just trade turbos. I would skip the fuel cone and save your money. I've seen your work. I'm sure you're competant enough to grind your own.

 

[Don Tanklage]

i have a gear vendors o. d. behind my nv4500



it splits 3rd great, but 4th is a different story



4th over is almost exactly the same ratio as 5th



going from 4th over to 5th it might drop 50 rpm...





i am still curious how far an engine will rev under a load with the stock spring and the high idle stop out???? anyone know?



thanks, don

 

[dpuckett]

My 91 would pull to about 2950-3000; run out of juice about 3250.



DP

 

[cerberusiam]

i have a gear vendors o. d. behind my nv4500



it splits 3rd great, but 4th is a different story



4th over is almost exactly the same ratio as 5th



going from 4th over to 5th it might drop 50 rpm...





i am still curious how far an engine will rev under a load with the stock spring and the high idle stop out???? anyone know?



thanks, don

In the neighborhood of 3000 +/- 100 providing you have enough fuel to run the higher r's. Free reving is a bit different than under a load. Under load if you don't have enough fuel you will not see the rpm's.



My 92 will pull about what I said with the setup I have that includes a pump that is a bit lazy on the top end.

 

[glhs]

Under load it will usually defuel about 4-500 less. So the answer would be 3100-3200... ... ... at least that's what mine was. You do need to check to make sure you have full pedal travel and that might require grinding the linkage stop or maybe some washers under the go pedal mount.

 

[JSchlachta]

This is an overlay of three runs the two lower runs are with stock gov spring and the last one is with 3200 rpm spring other things have changed such as injectors and a little more fueling I have the high rpm limit stet around 3200 rpm when I first put the spring in it would run to 2600 rpm which is too high for me and the overall power is down in the high rpm range.



Jim

 

[Don Tanklage]

thank you all

 

["Mad Max"]

Let me reattack the fuel pressure issue. Bill, forgive my ignorance on the piston lift pump. Are you saying to stay with the stock one or go with an aftermarket variety?



Also, Bill, about the go-fast goodies - we put them on my buddy TJ's rig - I traded him those for his expert bodywork talents on the RC .



My buddy has a FASS system on his 24V '99 rig, but if the pump isn't coming apart, and with a HX-35, do we really need fuel pressure 'augmentation'? If I can keep it all 'factory' then I'll be that much happier.



- M2

 

[Don Tanklage]

Well, here's the assembled mock-up for the driveline - just to see if it all actually bolts up - it does.



#ad




In the end, it'll be NV4500 + NP205 + GV overdrive + 4. 10's + 35" tire (285-70/R19. 5) = 1800 rpm @ 80 mph. Sweet.



- M2

max, i think your gear vendors unit is . 78 UNDERDRIVE, not overdrive



if so, that thing will be at 2500 rpm @ 80 mph!



better check it out...

 

[JLEONARD]

Whatever it is, Max gots himself about 200 feet of drivetrain I do believe!! Dang there boy, that's a heap of "stuff" going on under there.

 

["Mad Max"]

I can see how the . 78 ratio could be seen as an underdrive, but rest assured it is how they calculate the overdrive - take the speed and divide by . 78, and that will give the overdriven speed, verses multiplying by same ratio . Think of the numbers the same as gears in a transmission - in a NV4500, 1st is 5. 61 (engine rotates 5. 61 times for every transmission single output rotation), 2nd is 3. 04, 3rd = 1. 67, 4th = 1. 0 (direct drive - one engine rpm = one transmission rpm), then 5th is 0. 75 overdrive (engine rotates . 75 times per every 1 transmission output rpm, or, the transmission rotates more times than the engine), then, add the GV (. 78) and the engine rotates . 78 times for every overdriven (. 75) rpm of the transmission. With my setup, at 65 mph in 5th gear, with 4. 10's and 35" tires, the engine is turning 1900 rpm. Then, divide that mph by the . 78 GV ratio, and you get 83 mph at 1900 rpm.

I just re-read all that and gave myself a headache. Must add beer :-laf



And no doubt it's a lot of driveline , but it is all mated and all precision-aligned {cool}. The whole kit and kaboodle is pretty nice - Gear Vendors really did their homework on these units, and the adaptors are sweet.



The funny thing is, considering the rig I'm building and the overall chassis length (about 24' total), I'll still need a two-piece rear shaft



- M2

 

[Don Tanklage]

good deal...



have you dealt with the 5th gear problem that the 4500 is prone to?



tank

 

["Mad Max"]

not yet, but that's only because I haven't had the transmission rebuilt. There is a shop here in the Springs, Precision Standard, that knows all the voodoo (tricks) and the upgrades (hardware - 5th gear nut, hardened input, etc), and he's going to do the transmission for me, and the bonus is it's cheaper than buying one new. They really don't wear out, at least not the hardware - bearings, gaskets, seals - all replaceable as designed, but the transmission shifts good, and I want it built bulletproof, and that he can do {cool}.

- M2

 

[sdstriper]

I am curious having read a little on this one. Are you going to use the shaft from Quad4x4?

 

["Mad Max"]

Nope, I'm having it all done at the shop here, which will include the hardened input, and that's mainly due to there actually being a local shop at all - wasn't sure I'd find one, but if there's a local business where I live I'll give them the business all day long verses on-line, plus it gives me a local shop for any issues and future upgrdes.

Nothing against any aftermarket transmission supplier - none at all - No matter where the parts come from they're all good, and they're all needed for big power. I have the time and would rather do it in pieces verses a kit... just my style.



- M2

 

[sdstriper]

I too like your philosophy on the local shop and pieces parts rather than the kits. I do wonder though, from what I read on Quad 4X4 they're shaft seems to be the end-all to the problem, design-wise. Is there similar shafts available from other sources?