28 replies to this topic

[Zoomad]

You got the idea, geared up numerically speaking...

 

I've got tunerpro on another laptop and that's what I can use to tune the MEFI4 system with the 5.3.  I can get live data for sure, but it's a giant pain in the arse.   I got the software loaded to the laptop I use daily, but it will not connect to the ECM at all.  I've played with port settings and the like and it will not connect.  So I'm stuck using a dinosaur laptop running something like Windows 98 on it.  Trying to get help from the tunerpro guy is very similar to talking to a brick wall.  I think I'd get help from the brick wall sooner too.  

 

I do have my own Tech1 GM scan tool though, it just doesn't work with the MEFI4 system. 

 

Swapping for the sake of the fuel economy gains really won't pan out financially for sure.  Mine was pretty simple as the truck came to me without an engine.  Something had to go in there and I had a solid take out engine from a customer's truck.  Stock top on though it was way better, power and fuel economy compared to a stock TBI 350 that should have been in mine.  Hell, I could do burnouts pretty easy with the 35" tires.   Now not so much with the added weight on the rear I've got way too much traction for it to spin.  

 

If you get to CO, drop me a line.   There are a couple of places in the state that go by Four Mile, but as areas that have Elk hunting, it's probably between Salida and Buena Vista or near Leadville.   Both areas are only 2-3 hours from my home.  Pretty country up there as I've done a lot of wheeling around there.  Much this summer too.  

 

Glad we could compare notes too.  Always good to get the perspective.  I've got another buddy in Denver with a 77K5 and a very original FWC camper.  I mentioned him before in my thread here.  He's in the process swapping out the carb'd 350 for an L29 Vortec 454 too.  Again, it's an altitude thing.  He's only gone out a couple times in his and that was enough to start looking for something better as his 350 was wheezing all the way up the hill. 

[jmodge]

 I was disappointed when Chevy discontinued the small block, but no doubt these LS engines are way superior. I do hope to get out there and bring my quad with me. It would be interesting to see how the TBI adjusts to altitude. I will for sure give notice if and when I come out.

[ntsqd]

FWIW if I were going to be at altitude a lot I'd go turbo-diesel. This based on driving my old VW Caddy (pick-up) with low pressure turbo  (7psi Max) over the Million Dollar Highway, Durango to Ouray. It was just as slow at the Pass as it was at sea level.

I've also driven our CTD (6BT) with camper over that highway going the other direction and I've gone higher here in KA (Barcroft Station @ 12,400') with it. Same thing, the truck didn't know or care that it was at altitude. In the Caddy I passed a Texan in a 6.2 powered DRW flatbed pulling a gooseneck livestock trailer over the Pass. Even with it empty that truck was hurting up there. Turbo or not, when a Rabbit diesel passes you there's something wrong......

 

EDIT: I want to say that the '99 LS1 from a Fire-chicken Trans-Am that we put in a Jeep YJ had a throttle cable. It's been a while, I could be wrong, but I don't think so. Used a Ron Francis loom kit and I don't recall running wire to the throttle pedal. I'm also reasonably sure that it still had the Jeep pedal, but I HAVE slept since then.

Edited by ntsqd, 23 January 2019 - 03:21 AM.

[jmodge]

ntsqd,

 

 I'm starting to feel like deleting projects instead of doing them Curious how that altitude affects boost numbers. We actually have a couple alh tdi's with mild tunes and slight injector upgrades. I suppose your Caddy was waste gate? I wonder if an ecu controlled vnt would call for more more boost because the map is reading a lower pressure. I am assuming barometric pressure is lower at altitude?

 

zoomad,

 

 I never looked at your truck build, you guys are top notch pros, I am impressed. I will admit I am more like the guy who apoxyed the shift indicater. You don't by any chance still have a factory tach for the K5 do you?

[ntsqd]

As odd as it sounds I didn't pay much attention to the CTD's boost gauge while going over the Pass, but I did pay attention to the Caddy's boost gauge. No change in peak pressure, *might* have been a little slower achieving the peak boost - not sure, it has been 20-odd years since I took that trip.

 

I get whittling down projects, in the process of doing that myself.

 

I didn't say it, but I was thinking during the typing of my last post that for what you're mostly going to be doing I agree with Zoomad, what you've got works pretty well considering. I know that part throttle moves the torque peak around, but my preference is to try to gear so that cruise mph happens at a little under the Torque peak rpm. Reason being is that peak Torque RPM is the engine's BSFC, Best Specific Fuel Consumption, RPM. The RPM where the engine makes the most power for the least fuel.

[Zoomad]

map is reading a lower pressure. I am assuming barometric pressure is lower at altitude?

 

zoomad,

 

 I never looked at your truck build, you guys are top notch pros, I am impressed. I will admit I am more like the guy who apoxyed the shift indicater. You don't by any chance still have a factory tach for the K5 do you?

 

Much appreciated.  We are just a couple guys working out of a garage like most, one of which has a big case of OCD about factory appearance. I'm getting that way, but my buddy is certifiable.   Wait until you see the big block swap we do.  It's grown from being a 454 to an 8.1L by the way.  That should be fun..

 

I sold the complete factory tach cluster I had.  I have a tach left, but don't have the separate harness for it. I'm holding onto it in case I want to alter it to run with the 8.1.

[jmodge]

 Thanks for the responses guys, my best bet is to leave well enough alone on my truck and spend some time on the camper.  

 

 No problem on the tach, I do have a mini tach that I thought I would install in the empty lower left spot, but when I pulled it apart it seems a circuit board was in the way and I was not about to butcher it. I redid my underhood harness when I put the vortec heads on, as the old one runs beneath the valve covers and was oily. I raised it above the engine and ran a tach wire back into the cab. 

 

 So while considering the gear change, I can hook up a tach and vacuum gauge to see what the motor likes. I put a flat tappet cam with a profile that is very close to the roller cam in the '96 to '99 trucks, low torque curve. If I decide to go with a little taller tires eventually, 4.10's most likely. If not 3.90's are an off the shelf gear set for the 8.6" ring gear. 

 

 For that matter I could use several tire sizes to similate gear changes and note the changes in vacuum. less vacuum is less air, is less fuel? Could also check mileage using gps. I know the weight of the rotating mass changes things, but it should get me close. Any thoughts?

, 

[Vic Harder]

 For that matter I could use several tire sizes to similate gear changes and note the changes in vacuum. less vacuum is less air, is less fuel? Could also check mileage using gps. I know the weight of the rotating mass changes things, but it should get me close. Any thoughts?

, 

less vacuum means the throttle is open more, so more air and fuel.

[jmodge]

Right, I misquoted that.