[Jason@JacFab]

Not that I'm going to do it... But I have been thinking about it. I have a brand new TVS1320 that's been sitting on the shelf for a few years looking for a home... The thought has cross my mind to stick it on the intake side of the LTG...

Food for thought, the Volvo S60 is now a 2.0 that is twin charged (both supercharger, and turbocharger), putting out 362hp and 347tq...


Now there are a couple ways a guy could go about twin charging, a compound boost setup, or you can run them independent of each other with some creativity. I'll talk about compound boost first.

So when compound boosting, you're feeding the turbocharger boost directly into the supercharger. From what I've found, this essentially multiplies your boost from the TC (turbocharger) and the SC (supercharger). There is a formula based on the pressure ratios you can use to figure out the final boost number, but I won't get into that, instead I will post this handy chart...



So in theory, you can run both the SC and the TC in their maximum efficiency zones without running either one by itself so hard its into an inefficient range to get a big boost number. So for example, looking at the chart above, you can run the SC at 8psi max, and the TC at 8 psi max, and the final number will be 20.35 psi (around stock), while creating less heat from either the SC or TC, and probably way less than just a stock TC trying to push 20+ psi

Then, running them independently (non-compound), there is generally a diverter valve/flap of some kind that will switch the boost input to the engine from the SC to the TC. You run that SC at low rpm to get instant boost, power and TQ, and when it runs out of steam, the valve will switch the air tract so that the TC boost takes over for that top end power.

MY thought on this, to keep that simple, assuming it would work would be this... Most new age superchargers have a bypass valve that opens while an engine is idling... Assuming you plumb the TC right into the inlet of the SC, my thought is that when you want the TC to take over, have the bypass valve open to bypass the SC rotors and straight into the intake... This should relieve most of the compound boost effect easily, without all the extra BS.

Either way, in theory, you're getting instant boost off the line on low rpms with the supercharger where you would normally experience the turbo lag, and you get the top end pull of that turbo, while not running either the TC or the SC past it's point of max (or at least good) efficiency.

Thoughts?

[DarkFangz1100]

This guy took a lotus and twin charged it..couldn't we follow a similar build? But refine it further

[parish8]

I have considered this but more along the lines of a zl1 with a giant turbo added. People have done it in the past with supercharged cobras but have poor results. They actually report making more power after pulling off the blower.

I think they are using way too small of turbos and the same thing would happen to the stock Camaro turbo. It isn’t designed to flow tons of air at low boost. If your going to size a turbo for a zl1 you would want to consider that engine to be more like a 10.4L engine. 6.2L at 10psi from the blower would act like a 10.4L engine from the turbos perspective.

Normally if you wanted 1200hp a pair of 62mm turbos would be fine but you would never put anything that small on a 10.4L engine. They would choke off the engine. I can post up some turbo maps when I get home and it will make more sense.

I would love To take a zl1 and put a couple of 80mm or larger turbos on the thing.

[geoffchad]

If the goal is to make the same power, lets say 270hp from 2.0L turbo4, then you can do it with (say) 18psig from a turbocharger, like we do, or twin-charge - so maybe 7.5psig from the turbo and 7.5psig from the S/C.

The engine will see similar intake velocities and pressures and intercooling being equal make the same max power - but you're still flowing the same CFM through the turbo, just compressing it less (assuming you change your A/R for this to optimize the curve!). The advantage is at 2000rpm when you slam on the throttle you're pretty much instantly at 7.5psig already from the S/C, so your powerband is wider and flatter and throttle response is better as the turbo then (quickly... very quickly) catches up.

Volvo just decided their turbo4 would be ~350hp and didn't want it to feel peaky or have tons of lag like a single large turbo would. Ford, when faced with the same problem, increased displacement.

W-Body guys have done this too, trying to turbocharge the 3.8L S/C and the results are consistent that if you want more raw power you're better off with a single large turbo or supercharger than the complications and headaches of twin-charging. Same with twin-turbo engines as well.

For a street driven daily driver, a positive displacement blower is my favorite power adder. Their "instant power" is pretty nice. In the case of the LTG I'd rather stroke the engine an then put on a slightly bigger turbo through.

Originally Posted by cooper1965

Sounds like a cool ideal. Great boost off the line, quick turbo spool.. I wonder though, and this is all new to me, but would the cost and effort really be worth the gains as far as reducing your ET? I mean, if it's going to cap off around 8psi, how much could you realistically gain MPH or 60' wise ? Again, this is a new concept to me, but would there even be a noticeable gain on the dyno?

The max psig is the same, but the way it gets there is different. This certainly isn't cost effective, it's done to make a wider and flatter torque curve. Look at LTGs that are boosted higher and harder toward the 350hp mark - they give up power down low but make TONS up top. twin-charging like this robs a relatively small amount of that top peak and adds it several times over in down low power and throttle response.

[Zzsteve]

we have done this in the past with both the GTP, and the LSJ supercharged cobalts. mixed reviews really, but ill tell you that both cars were substantially faster after pulling the blower off. i have driven several twin charged cobalts that made north of 500 WHP, and was not terribly impressed (compared to a strictly turbo only setup). its really hard on parts, overly complex, and just generally works better on paper than it does in any practical application.

with an unrestricive intake manifold, and a "good" supercharger, i would expect results to be considerably better than blowing through crappy old gen 3 M90s like we were doing many many moons ago.

my vote: a properly sized turbo, and a tiny shot of the sauce to get you out of the hole

[Michigan1LTRS]

Originally Posted by Zzsteve

my vote: a properly sized turbo, and a tiny shot of the sauce to get you out of the hole

Yes!!

[vaspen]

To help super low endrpm for the s.c, mercedes, designed the m60 ? To be clutch driven to only engage above 1800rpm to help with the motor at idle being it was a 4 banger

[Jason@JacFab]

OK... So good for exotic builds, mainly for eye candy at shows... Probably not so great for performance. Scrap that idea.

[ChicagoTommy]

Originally Posted by Jason@

OK... So good for exotic builds, mainly for eye candy at shows... Probably not so great for performance. Scrap that idea.

Yeah, unless you're an OE manufacturer with an unlimited R&D budget, no one is twincharging an LTG. This is exactly why ZZP sells a block off plate for the M90 supercharger that comes stock on the L67 engines. You remove the OE drive coupling & rotors, then replace with the block off plate.

[Centerforce_Clutches]

Originally Posted by Zzsteve

we have done this in the past with both the GTP, and the LSJ supercharged cobalts. mixed reviews really, but ill tell you that both cars were substantially faster after pulling the blower off. i have driven several twin charged cobalts that made north of 500 WHP, and was not terribly impressed (compared to a strictly turbo only setup). its really hard on parts, overly complex, and just generally works better on paper than it does in any practical application.

with an unrestricive intake manifold, and a "good" supercharger, i would expect results to be considerably better than blowing through crappy old gen 3 M90s like we were doing many many moons ago.

my vote: a properly sized turbo, and a tiny shot of the sauce to get you out of the hole

This is basically our experience, too. One of our DYAD clutches was used in a dual charged (supercharged twin turbo) coyote swapped 65 mustang and made 1000 wheel hp, which plenty of people are making with standard single or twin turbo setups. Its neat to see something original done like that, but not sure if its worth the money and extra complexity to the average owner.

[ChicagoTommy]

Originally Posted by Centerforce_Clutches

This is basically our experience, too. One of our DYAD clutches was used in a dual charged (supercharged twin turbo) coyote swapped 65 mustang and made 1000 wheel hp, which plenty of people are making with standard single or twin turbo setups. Its neat to see something original done like that, but not sure if its worth the money and extra complexity to the average owner.

Oh man... I didn't know you guys posted on this forum! Be prepared for a bunch of LTG guys to start asking you for clutches! There is a flexplate thread in this forum where we've started discussing aftermarket offerings. I couldn't remember if you guys had released anything.