Turbo Charging

[kacyk]

Is this for real? If it is, I have a 2003 Yukon that's craving some extra punch! I wonder if it would work on a H2?

Turbo

[kacyk]

Is this for real? If it is, I have a 2003 Yukon that's craving some extra punch! I wonder if it would work on a H2?

Turbo

[Fastest H-Town Realtor]

Until I see live dyno work and street testing, I call BS. The "cooler charge" theory goes against all the modern ideals of exhaust gas flow proficiency. If a cooler exhaust meant better exhaust gas velocity, then the Jet Hot coatings, that already have been dyno proven, would not be neccessary.

The turn around time for the exhaust to speed up the impeller, then deliver the boost has got to be .5-.75 of a second without load. With added load to the motor, the lag can only get worse.

With a shift point on the test vehicle of that article being at 5800rpm, my theory shows to be peliminarily correct. Look at the relatively low torque readings vs. the HP reads. On a lower rpm turbo kit, the torque should outdo the hp. The test dyno proves to me that the turbo is taking its time to spool up. Prolly not hitting real boost until 3500-4000 rpm. For a turbo install, thats high rpm for boost.

Color me not impressed. Anyone want to offer other perspectives?

[B]

stock 6.0, 3200 stall, 3:08s
If this link works, you can see how well it does work. Your theory is a little flawed as turbos work off load. This is a great bolt on street kit that provides great results.
I saw this, so I thought I would post to add some insight from someone who has installed many of these kits and can confirm the results. My own car went from 310/325 to 412/451 at 5psi.
Just in case the link doesnt work, the truck ran 11.99.

[PARAGON]

We've discussed the STS as well as other turbos on here recently.

The theory is sound, while the application might be off some. The STS won some innovative design awards and offers some unique looks at where turbos can possible go. Header coatings' purpose is not to keep the exhaust gases hotter, that is just a product of what their real purpose is, which is the retain the heat in the exhaust system and not bleed it into the engine bay.

In theory, the exhaust gas idea is somewhat the reverse of the increasing the intake charge. Cooler gas is more dense and therefore can react with the turbine more effeciently as opposed to hotter less dense air.

Your other observations are somewhat on target though, but that, IMO, is a product of application and not of sound theory. For instance, turbos on diesel engines start creating boost as low as 1200 RPM. So you can obviously create boost at lower RPM with turbo as long as the properly handle the higher RPMs with a wastegate control or something. So, it is possible to have a smaller impeller on the STS type and spin the boost up much sooner to get the torque.

It really depends on what you are wanting to accomplish. I believe most H2 owners are really wanting higher torque numbers but there are situations that having a higher HP number at higher RPMs would be desired. Balancing these two needs is where everything is headed.

The turbo in this application might have spooling time but obviously a turbo can be designed to lessen or do away with it.

As far as the idea of a turn around time, that seemed logical but I don't know how noticeable the lag would be just because of the extra piping. If the turbo was a smaller one that spooled up sooner and created boost at lower RPMs, there would be a charge in the intake pipe to begin with. Now, go to WOT, and there would be some "time" lost between the sucking of the air and the increasing of the pressure all along the pipe. Since there is more volume of air that has to increase in PSI your idea of delay makes sense. The question would be how much of a delay.

But it's innovations like this that drives the technology to the point that we end up with the right setup. I don't see much improvement or innovation in the application of the screw supercharger and there is a certain efficiency that goes with the turbo systems that would be a plus.

I think it boils down to individual need and application. Personally, I have no desire for a system that starts creating boost anywhere above 2000 RPM. I would want boost to occur around 1500 RPM or so to increase the available torque.

[Fastest H-Town Realtor]

B-

Sweet truck you have there. Could you elaborate on the "off load" idea? Also, my post of not hitting boost until late rpms is kinda validated with the realization of a 3200 rpm stall convert. It lets the turbo spool.

Paragon-

True, the coating keeps under hood temps more in check, but its primary purpose is to keep exhaust gasses speed up thru the header. This is
a snip-it from the Jet hot site:

"Nevertheless, JET-HOT Sterling will normally boost power when applied to headers for two reasons. First, the coating promotes denser, more potent fuel/air charges by insulating the engine bay from exhaust heat. At the same time, it accelerates the pulsed-vacuum effect on “tuned” headers, resulting in more effective scavenging of cylinders. The increased velocity of exhaust gases produced by higher exit inertia not only clears each cylinder more quickly; it also draws in the next fuel/air charge more efficiently."

The exhaust gasses staying hot keep the molecules more active, a desired effect in the header. To cool the gasses would make them less active and slow down the flow. I believe this is a therm-dyn law. Dont quote me on it,though. The diesel turbos are positioned very close to the exhaust outlet of the head, keeping flow high. Add in a powervalve downwind of the turbo to keep pressure active within the exhaust and a turbo system designed to make boost early, then bleed of excess flow with the wastegate and you have a responsive turbo set up-If the unit was any other way, a turbo diesel would be a bad idea because diesels shut down way early than the gas counterparts. Redline on a diesel is 4K.

A small(er) turbo that will provide low rpm pressures will map out(pressure maps) short of flow on the 6L engine. This will severly limit top end power and overwork a turbo. Any turbo install is a compromise, as is a blower install.

My experience with turbos is limited to systems I have hobbled together from junk yard parts and reading all I can from design gurus like Hugh MacInnes.

The 6400lb/325hp H2 needs low end grunt to make a difference. A 600hp/265ftlb engine would diminish the experience, whereas a 325hp/500ftlb engine would be pure sex(shut up drty ). One major advantage of the turbo system is not sacraficing up to 70hp to drive the blower. For this reason, I think a good turbo system would better enhance the driving experience than a lycholm screw/roots type blower kit, although I'm not willing to hand my warranty over to GM on a silver platter to be voided. I can yank the package off of the engine with little problem, but the turbo will be problematic for re-running exhaust. I also like the intercooler/intake manifold set up much better. Again, opinion.

As I set up to open a 4cyl/fwd perfomance shop later this year, I think the front vs. rear turbo debate will be a fun project to tackle. I will attempt to build both and compare results. Be warned though, I only use dyno testing for tuning issues. My kuddos are handed out on the track/street. Dyno kings and trailor queens dont excite me.

[KenP]

I love the sound of a turbo spooling up. Really nice.

[NU2H2]

I think you may have misunderstood what "B" meant when he said Off Load. Maybe should have been worded more like under load. The turbo will spool up sooner under load than "under loaded" Hence when you tow with a turbo you generally see full boost and full TQ much much sooner than regular driving. generally 1800-2000 under load than 2800-3000 no load. This will be seen when used with a big truck like the H2. I personally would like to see a turbocharged H2 tooling around town blowing the doors of sport trucks might make for a nice change.
Jonathan

[PARAGON]

I'll disagree with you completely on the idea that header coatings' "primary purpose is to keep exhaust gasses speed up thru the header." Again that is the byproduct of attempting to achieve lower engine bay temps. Besides, the scavenging of the cylinder only occurs at the exhaust manifold/header and the increase in temperature creates more vacuum pulling more of the exhaust air out of the cylinder more efficiently. This is the purpose of headers altogether to begin with. Increased heat is not an advantage nor a factor down the line, though. The exhaust temps drop naturally. The STS system is simply taking advantage of this natural drop by moving the turbo further down the line. The STS is not proposing that it lowers the exhaust temp, just that it takes advantage of the lower exhaust temps. Again, further down the line the gases are naturally cooler and cooler air is more dense and dense air acting on the blades are more efficient as compared to hotter air. I think that is the point being lost here.

You are right it is thermodynamics. Cooler air is more dense. If there was some way to spin the turbos with only cold air, it would be more desirable than using hot air because denser air reacts on the blades more efficiently. It's just like airplane wings. Planes get more lift when the temps outside are cooler as opposed to hotter. The molecules are more closely packed together creating the effect of more molecules moving across the wing surface. The same idea applies to the turbo. If there are more molecules moving against a turbo blade it moves the turbo more efficiently as compared to hotter air where there is less molecules in the same volume of air.

It's applying all of this where it will make the difference though. So much R&D needs to be done to achieve the desired results. I agree the H2 needs more torque than extra HP but smaller turbos tend to spool quicker (simply due to having to spin less mass) and create boost at lower RPMS. I don't have all the answers, own a shop, or even tune, but I do like to see the continued innovation.

[PARAGON]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by NU2H2:
I think you may have misunderstood what "B" meant when he said Off Load. Maybe should have been worded more like under load. The turbo will spool up sooner under load than "under loaded" Hence when you tow with a turbo you generally see full boost and full TQ much much sooner than regular driving. generally 1800-2000 under load than 2800-3000 no load. This will be seen when used with a big truck like the H2. I personally would like to see a turbocharged H2 tooling around town blowing the doors of sport trucks might make for a nice change.
Jonathan </div></BLOCKQUOTE>I don't believe I have heard this before. It sounds like you are saying that an engine loaded up at a given RPM will create more boost than one smoothly running at the same RPM. I don't know if I agree or disagree with that completely, but if I had to say right now, I would disagree.

The engine only moves so much air at a given RPM. Just because reverse pressure is being applied through the driveline and the vehicle is working harder to pull a load at that given RPM, it wouldn't be moving more air through the engine. Turbos are as much a product of engine RPM as screw superchargers. If the RPMs are low and the turbo is not tuned for that low of an RPM, creating more load through the driveline would not increase the exhaust outflow thereby increasing the boost from the Turbo.

That's my opinion and again that's the first time I have heard that theory so I haven't had time to give it much thought.

[PARAGON]

Along those lines, one could build a turbo that had 5 psi boost at 500 RPM, it just wouldn't be desirable. You would TUNE the turbo system to map out the boost that is best suited for the vehicle AND desires of the owner. This would include the size of the turbo, pitch of blades, how the "overboost" is handled at higher RPM through a controller and wastgate(s).

[NU2H2]

Loading a turbo is exactly what you do with a stall converter.

[PARAGON]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by NU2H2:
Loading a turbo is exactly what you do with a stall converter. </div></BLOCKQUOTE>Right, but what does that have to do with your comments about driving conditions affecting boost.

A torque converter reacts relative to engine RPM not load from the driveline. So a converter allows the transmission to react at a higher RPM before "engaging" to take better advantage of the best torque band for that engine.

Of course, this is how I understand it, but I could be wrong since I have little experience with tuning cars.

[PARAGON]

I don't know if I understand very well what I just said.

My point is that the torque converter allows for the engine to reach higher RPMs before it "engages" the transmission. So a higher stall means the engine is turning higher RPMs upon launch and it's those higher engine RPMs that "loads up" the turbo.

[NU2H2]

Sounds like you have a good handle on the stall idea. The turbo will react different to load. Just like towing a 7000lb trailer you have to produce more power to move the weight, hence more RPMs. The more RPMs produced the more boost produced when under load to a certain point that point being governed by the wastegate. The turbo will not produce boost when not under load ie neutral therefore turbos react different under different load conditions. More load more torque produced lower in the rev range. Stalling up the car with a stall converter is "loading" up the motor through the drivetrain.
Do I sound like I am rambling?

[KenP]

Guys, put the vehicle in Cruise Control and head down the highway. As you approach a very moderate hill you will notice the boost gauge go from vacuum to boost without a change in gears and little, if any, change in rpm.

Did I say I love the sound of a turbo spooling up? I had a 5k stall on my Buick. Talk about a crazy sound. (Just thought I 'd throw that in for fun.)

[NU2H2]

yep exactly

[PARAGON]

Ok, I don't think we were looking at it the same way. I tend to isolate the factor being discussed and let all else remain the same. If you were at agressive throttle pulling a trailer, you most likely will NOT hit boost sooner in the RPM range than if you were not pulling the trailer. The driveline load does not matter since under WOT the engine is at it's most efficient (moving the most molecules).

Now, using Ken's scenario, let's assume RPMs do not change. Throttle positon does change due to the cruise control input. This increases gas input which increases exhaust density and will spin the turbo creating more boost than it was when it was just cruising along on the flat surface. I guess what I am saying is that if the boost is mapped out on a dyno and it hits Xpsi boost at XXXXrpm, adding a trailer is not going to change those numbers because on the dyno the engine was stressed up by being taken to WOT. The engine would be at it's threshold with or without the extra load.

So, my point is that if you are moving along, a change other than additional driveline load has to occur to reach more boost. Simply loading the engine doesn't do it, as in Ken's example more throttle (and more gas) is required and boost does increase.

I do have some experience with turbos since we have 2 turbo diesels for the farm. Both a powerstroke and a duramax. But I think this was more of misunderstanding or incomplete explanation than being right or wrong.

[NU2H2]

Maybe so, but the we can get into why we use eddie current or load bearing dyno machines. Using load will affect how the power is made. I have seen turbos producing full boost by 1800-2000 when towing and the same vehicle not producing full boost until 2800-3000 RPM not towing therefore load is a factor.
I agree this point is mute and getting beaten to death

[LasVegas]

Not a turbocharging expert but have many hours flying sophisticated tc aircraft & I'll limit this to those generating 100's not 1,000s of hp. Some aircraft are turbocharged just to maintain sea level pressure (29.92 in mercury) at altitude. Others actually boost to 40, 50 or more inches and on top of that bleed off air to pressurize the vessel (cabin) to 5 psi differential or more. Suffice it to say that plenty of boost can be had from a turbocharger. Most aircraft never exceed 3000 rpm at takeoff and more often it's down around 2700 & develops full boost with nearly -0- lag. So rpm is NOT the controling factor. It's all a matter of the size turbocharger & the controller set up to do whatever you want to accomplish. Early tc aircraft actually had manually controlled wastegates with no controller at all. I think turbochargers are more adaptable than roots type chargers and if someone were to design a good one for H2s I'd consider doing it.

Okay, my pet peeve. Cars don't have motors, they have engines. Motors, as in electric motors require external power sources to generate energy. Engines generate energy without external power sources. Sorry, goes back to my school shop days.