Supercharger Heaven

[Mb30sdl]

In my opinion SC is better for low rpm (off road use). You get instant linear boost from idle so you can control wheelspin easier.

 

[RamRod]

Yes a turbo kicks in at a certain rpm, thats because it gets powered from the exhaust pushing on it. The sc takes power directly from the engine via belts, so its always on.

This is not true on all super chargers, for example the one on my Alpha is kicked on once the vacume pressure is at a certain point (you can hear it kick in).

This is to make it more driveable and more fuel efficent

 

[MaxPF]

My understanding is that a SC gives you the sensation of a bigger engine (boost is linear) where turbo tends to be peaky, unless you go variable vane turbo

That's a generalization based on 40 year old technology. As you pointed out, variable geometry turbos eliminate the lag. For a demonstration, go drive a Ford F150 with the Ecoboost engine. Or any modern turbodiesel. Even a properly sized ball bearing turbo (fixed geometry) will light extremely quickly if sized properly.

 

[MaxPF]

In my opinion SC is better for low rpm (off road use). You get instant linear boost from idle so you can control wheelspin easier.

I would have agreed, but my experience is that you never build boost off-road anyway. Granted we're talking a diesel engine in my case, but the principle is the same. I have never seen my boost gauge come off the zero psi peg while off-road. It seems I just never load the engine up enough to light the turbo.

 

[Mb30sdl]

No my F350 takes ~100 feet before boost kick in, same was with my old 300SDL. It's not instant. But with SC you can probably get mild boost from 1500rpm, in low range?

 

[RamRod]

When I get my boost gauge put in I'll watch to see what happens while off road!


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[Sennin]

That's a generalization based on 40 year old technology. As you pointed out, variable geometry turbos eliminate the lag. For a demonstration, go drive a Ford F150 with the Ecoboost engine. Or any modern turbodiesel. Even a properly sized ball bearing turbo (fixed geometry) will light extremely quickly if sized properly.

True, but what I found is that the manufacturers actually manipulatee the fueling to achieve the smoothness youre referring to, as soon as you remove the limitations you actually feel the "peakyness" of a turbo still, althou you cant feel the lag any more.

One place I can say I have experienced the turbo lag still was at high altitude where I had to revv for 20 seconds to get boost going to pull away and this was only at 3500m above sea level. But what was interesting was that I took both my 3.7 and 5.3 H3's to the same spot and didnt experience any performance loss, interesting

 

[MaxPF]

True, but what I found is that the manufacturers actually manipulatee the fueling to achieve the smoothness youre referring to, as soon as you remove the limitations you actually feel the "peakyness" of a turbo still, althou you cant feel the lag any more.

One place I can say I have experienced the turbo lag still was at high altitude where I had to revv for 20 seconds to get boost going to pull away and this was only at 3500m above sea level. But what was interesting was that I took both my 3.7 and 5.3 H3's to the same spot and didnt experience any performance loss, interesting

Yup, turbo lag increases with altitude. The reason is pretty basic - exhaust gas spins the turbine. Higher altitude means less pre-boost exhaust flow, which translates to more lag. Again, variable geometry turbos help tremendously. My Cummins takes significantly longer to spool at high altitude, but because of the wastegate configuration I can achieve the same absolute manifold pressure at altitude as at sea level. Thus the engine can make as much power at 3000m+ as sea level.

I guarantee your 3.7 and 5.3 were way down on power. Power loss is proportional to air pressure, which drops with increasing altitude. This is why piston engine aircraft designed for high altitude operation are universally turbocharged. Conventional supercharger systems (i.e. all automotive superchargers) will lose power as well since they operate at fixed pressure ratios. However, they will still have more power than the same engine which is normally aspirated.

 

[Sennin]

Yup, turbo lag increases with altitude. The reason is pretty basic - exhaust gas spins the turbine. Higher altitude means less pre-boost exhaust flow, which translates to more lag. Again, variable geometry turbos help tremendously. My Cummins takes significantly longer to spool at high altitude, but because of the wastegate configuration I can achieve the same absolute manifold pressure at altitude as at sea level. Thus the engine can make as much power at 3000m+ as sea level.

I guarantee your 3.7 and 5.3 were way down on power. Power loss is proportional to air pressure, which drops with increasing altitude. This is why piston engine aircraft designed for high altitude operation are universally turbocharged. Conventional supercharger systems (i.e. all automotive superchargers) will lose power as well since they operate at fixed pressure ratios. However, they will still have more power than the same engine which is normally aspirated.

Im actually a mechanical engineer, and my final year project was to design and build a pizoe-electric spark plug that fires on compression pressure and thus eliminating the whole spark ignition system. Although we achieved it, there is still a hell of a long way to go before it will ever be implimented due to the variation in pressure. One of the possible solutions was t+s (turbo and supercharger on same engine) to ensure constant pressure in the cylinders. The other problem is advancing and retarding spark timing and that will have to happen with logic control etc.

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[hodges81]

So..... My question is where can I get a SC for my 2006 3.5 H3???

 

[Cajun_Tiger_Hummer]

So..... My question is where can I get a SC for my 2006 3.5 H3???

+1 This!

 

[hodges81]

So i'm guessing theres no kits

 

[soct]

So I'm guessing theres no kits

No. I have been looking too. They are all out of production.

 

[5gn-h3t]

A little closure to this story:

I installed the kit, got everything working/running. Very noticeable power increase without any tune at all. I couldn't and still can't find anyone local with an AWD dyno that can tune this. I found one reputable person that can e-mail me a baseline tune but warned about running it hard without getting it properly dyno tuned.

I've decided to sell the kit and do a V8 swap. "But it still needs to be tuned!," you say. I know, I'm nuts. There is much more NA V8 support out there and I feel I can get most of the hard stuff accomplished via e-mail. If not, I'll be the ass staring at a laptop for months trying to figure it out.

The kit is more complete and has been slightly upgraded since I purchased it. The kit's mounting brackets for the intercooler are a joke (thin bent steel). I made a much stronger one from machined aluminum plate. I also made a block off plate for the air injection system so the kit can be installed on an '07+ truck as well as an '06. I made and acquired many parts that were not originally included. I'm including an '06-style MAF (required for kit, plugs right into any year I5 harness), cooler heat range spark plugs, the injector harness that I made (looks OEM), Rotrex traction oil for the supercharger, and whatever else I've collected for it.

I'm asking $3500 for everything shipped in the US. Anyone that is serious can PM me or call/text me at 570-947-0854. My name is Tom and I'd be happy to answer any questions. You can text me 24/7. Kit should fit anything with an I-5 in it. I'll also put up a for sale thread once I get some detailed pics.

I'm picking up an LH6 short block tomorrow.

 

[MaxPF]

Short block? Are you sure you don't want a complete engine? It usually ends up being much cheaper...

 

[5gn-h3t]

I will eventually get a complete engine. I got it really cheap and it was only 10 minutes away.

 

[Steve #1]

I can understand if you want to move on, but I'm sure you could find someone to tune it. Anyone with a little experience could get you a tune to put you in the ball park then fine tune it after a little data logging. If you have a local AWD Dyno and they just don't know how GM find a GM tuner and have them go to they dyno with you or find somewhere else with a dyno or pull the front shaft and have it tuned on a 2WD dyno. I can think of a lot of options that are a lot cheaper and a lot easier than an engine swap.