Pie in the sky supercharger thread

[rob h]

I can only tell ya with my experience. For instance my blower on my 408 comes in at 2400, it can come in sooner. I tried that and all it does is spin tires and make it a complete hand full. Honestly never looked into a turbo with the truck being so big n heavy. I Probably should of tho, maybe it was a better way. I just wanted less parts involved to worry about.Boost comes In it's more fuel air and timing and meth injection..lol..on mine. At 2400 it starts and goes up with rpm, at 5k it's all in at 12psi. That's around 120hp, a nice bump in power.

It's not what people wanna hear but...Wouldn't it be better tho to put a 5.3 or a 6.0 with a cam in it..? Its injected, plentiful, runs well and is fairly cheap.

 

[rob h]

And yes I keep seeing the decade word about my rides..lol.. things take time to perfect, some are never done. Both those rides I look at now tho...more money than brains but they are fun..lol... carry on.

 

[my kids took the truck]

And yes I keep seeing the decade word about my rides.

I bought my K5 in 1993, I am working on decade three.

The engine change is a possibility. However, I live in an apartment and put in 85 hours last week at work (I saw you work in nature's garage). I used to use my grandpa's shop (semi abandoned deep in woods full of flathead tools), but cousin issues. My father-in-law's cramped driveway is my new shop. My wife also has a rule, if it isn't broken we don't fix it. Right now, it isn't broken. It would just be nice.

 

[shady]

A good hard burnout and a convenient oil leak would fix that

 

[Blue85]

Electronic timing control; I am guessing this is Mallory-type control on top of the current HEI?

My wife wants more stoplight tourqe so she can just dump the clutch. More or less.

Typically you'll want a way to retard the timing when you get into the boost. With a mild setup you might be able to just make the vacuum advance come in sooner and back off the initial or something like that, but being able to actually program can help with any pinging issues that can arise - instead of pushing you towards race gas or e85.

More stoplight torque? Like a gear swap?

This is key. I don't usually get to 2,000 RPM. Anything over that and people on bikes start looking over to see what is coming (just flowmasters, it seems quiet).

What changes when boost comes in? I can reasearch, but what is a lower RPM of boost with different types of supercharger? Turbo usually is higher which is why I am asking about supercharger.

On a roots blower boost doesn't "come in" unless something is opening and closing a bypass valve. The speed of the blower is always an exact ratio of the engine speed, so once the throttle is opened a certain amount you start making boost. Here's the N/A vs. SC 3800, where you can see it's adding about 50 lb-ft from 1000RPM to nearly 5000. At higher RPM torque falls off from the hot air and reduced timing. A screw-type blower is pretty much the best thing for low end torque (other than cubes) and no lag, but not very efficient up high.

 

[my kids took the truck]

Not that it is apples to apples but a shop done regear is $2,500 (plus replacement lockers since everything is apart); while I rebuilt an entire GM12 bolt years ago and was surprised how easy it is, idk -- I like shops these days.

That would get me a long ways towards a $3,000 supercharger (installed in f-in-laws driveway because he'd help on something like that -- he is brewery facilities and while he can't fix a lightswitch in the house he can make a boiler humm at work; gear change, he wouldn't even come outside to hand me a beer).

 

[rob h]

I agree with the re-gear idea, nothing crazy tho so on the highway it doesn't rev high. What kills you is the low compression, it needs more to be n/a to have the power you want. With the supercharger and low boost i think as long as you have a wideband 02 and good ignition it will work fine but the ignition part i'm not sure. Too much timing will not be good and cause spark knock plus you will need to run premium fuel. Unless the timing is limited to a certain degree but that will be for you to find out. It will gain pep for sure, if your set on it i'd look for a used one. They have to be out there, i can ask a buddy if you want, his sits on the shelf in the shop.

The post above with the engine heat pulling timing is also why the newer stuff is inter cooled, i went thru hell with my inter cooled system keeping it cool with 12 psi. I had to get a bigger reservoir, intercooler and pump. It works now but i bet i have 800.00 plus in just that.

 

[CyberSniper]

For the cost of a newish (read: usable without rebuilding it completely) blower you can get a used L9H or preferably L86 6.2L. Weighs a lot less and easy to get 450hp/500ftlbs without opening the motor.

 

[my kids took the truck]

This should have been titled the regear-supercharger-L86 thread. All three sounds like the solution. That is real pie in the sky.

Nobody has said go electric lol

A key variable is gas mileage. Gears will be lower. I don't know about L86. Supercharged is good for +3 miles per gallon. In the long run that will payoff.

 

[Blue85]

Supercharged is good for +3 miles per gallon. In the long run that will payoff.

Don't see how that's possible. MPG should be the same as now or a little lower. Or you have a lot of fun with it, quite a bit lower. MPG from the gear change is hard to predict, and based on your mix of driving.

 

[rob h]

Don't see how that's possible. MPG should be the same as now or a little lower. Or you have a lot of fun with it, quite a bit lower. MPG from the gear change is hard to predict, and based on your mix of driving.

Haha, exactly you will enjoy the power and the mpg will be worse. Although the idea of the supercharger bypass tho is to run around without using boost until its needed..lol.( like mine no boost until 2400 rpm) Still think the gear change is a good idea or just an ls swap..lol.

 

[my kids took the truck]

Haha, exactly you will enjoy the power and the mpg will be worse.

Can't argue against gear change -- 3.73 would put me at 2,500 RPM at 65 MPH.

Check out this discussion about fuel economy. It is a good balance: There is professor X with "by the physics it must be worse fuel economy." Then there is pragmatic Joe whose brother's truck got 20% improved fuel economy when he added a supercharger.

https://www.thirdgen.org/forums/tech-general-engine/611079-time-settle-debate-better.html

The supercharger should be able to take hills and accelerate out of curves with less fuel -- I think the above discussion is between straight line constant 65 MPH (less economy) and real world mild driving (more economy).

 

[Blue85]

I don't know. Maybe, but I can't see 3MPG. Biggest savings are probably from keeping you in a tall differential gear and maybe downshifting less. No way it would ever pay itself off.

It's pretty hard to go from N/A to forced while changing nothing else. It's inherently a change to the intake and/or exhaust, plus tuning changes. Roots shifts the power band down, so they're usually matched to steeper gears in a street rod and than can increase MPG. For a fair comparison, you should dyno tune the N/A setup before going forced, but typically you see rough-tuned (driveway) N/A compared to professionally (dyno) tuned forced.

Power is basically volumetric efficiency * displacement * fuel. You do see an increase in volumetric efficiency to go along with your increased drag/restriction. For S/C, you're also bringing the VE peak lower in the band. There is also some effect of a blower on a carb that is supposed to help atomization, but that's really only closing the gap on EFI. Haters bag on roots blowers for the "large parasitic drag" on the engine, but I think it's also reducing the pumping losses of the engine by doing some of that work.

 

[CyberSniper]

L86 makes north of 300ftlbs at the rubber at 1300rpm. Find them at pick-n-pulls for $3500.

Run-of-the-mill tree-fiddy is fine, but I would never put excessive money into one anymore. The best part about them is they're cheap. Don't ruin that.

 

[my kids took the truck]

The best part about them is they're cheap. Don't ruin that.

In the back of my mind I was thinking there would be some good used blowers with low miles. What you said about 350 ci means they really should be laying around.

Also

"No way it would ever pay itself off."

I didn't run the numbers. Long long payoff period right.

I am heading out for a four-hour round trip with some highway grade -- which I don't drive much anymore except a few times a month (as in drive anything anywhere; all Lyft, walk, commute train, and bus). I put in colder plugs a few weeks ago, though didn't change the timing to take advantage of it. Let's see how it drives today.

 

[mtnman]

The benefit of any “forced induction” is increased volumetric efficiency. Forcing the air in means better use of available displacement. Great running/tuned N/A engines can approach 85-90% VE. Forced induction engines routinely achieve above 100%... Over 100% VE engines can easily be driven efficiently, if you can keep your foot out of it! Every time I do something to make more power I use it all! But fuel mileage has NEVER been something I care about...

 

[Hogback Fabrication]

I'm 100% for forced induction, especially at altitude where I live.

But I wouldn't count on better MPG with a supercharger. And I wouldn't put a lot of stake in an internet post from a guy who's brother got 30+ mpg from a supercharged V8 pickup

 

[my kids took the truck]

fuel mileage has NEVER been something I care about...

You are not looking for a bump from 18 mpg to 21 mpg to really make that difference /s

Off-road capability is important. However, driving 70 mph there without draining my bank account seems to have a big impact on if I am even slowly driving this K5 through muddy twisty washes in the first place.

Update on the trip yesterday. I was holding off on recurving my ignition advance until I was confident my plugs were not going to foul (too cold). They seem fine. These are long tip plugs, I could push it further and go short tip. When I get time, I will recurve my timing. That should put some torque in the bottom end. Maybe is enough.

I checked the stretch of highway that gave me a problem. It is a long mountain 6.6% grade with long curves I have to slow to maybe 55 mph -- or my kids start to yell that it's a roller coaster ride. For a comparison, I checked another grade that is over smaller hills in the valley, it is a straight shot up to the grade and up the hill, it is also 6.6% for a comparable stretch. I hit that section this weekend and didn't even notice I'd covered that stretch until I was near the top of the hill, there was no power loss at ~70 mph (2,100 rpm). I have this narrow hole in my 3rd gear to 4th gear power band. It is too fast for 3rd and too slow for 4th. So I just sort of floor it and let the power valve and air valve take over as I slowly loose speed and see if I will crest the grade before I lose rpm (1,500 rpm to 2,000 rpm). I am a big fan of excess acceleration potential in all situations. It is right about 1,900 rpm in 4th on a long 6.6% slope that things start to go to shit (with worn out 32" tires it was nbd).

Looking for a cheap/quick fix. 50 HP NOS shot /s

Or, I could just take the real low-buck fix, go up the hill at 45 mph in 3rd like my grandpa would have and enjoy the scenery (grandpa would have cracked open a beer to pass the time too).

EDIT: It turns out 6% grade is the maximum on interstates -- so this is sort of a niche issue since I shouldn't ever encounter 6.6% https://arstechnica.com/civis/viewtopic.php?t=1109365 Here you go, my problem statement that I will pitch to my wife: I need a supercharger for an oddball section of highway we drive one or twice a year because I don't want to slow down and it seems unsafe to drive faster since I have our kids in the truck. Yeah, let's throw $4k at that... Maybe I should put the sway bar back on and take the corners /s