Twin turbo setups build boost faster and generally peak between low to mid rpm's. Alot of AWD cars have TT setups because they can make more torque off the line and not have to worry about traction. Also rally cars are limited to 300hp so they take advantage of this with a twin turbo setup that produces 300hp throughmost ofthe engines rpm range.

 

And no, two turbos do not automatically spool faster than one. It all boils down to the size of the turbo(s) vs. the size of the engine spinning them. Two small turbos with the same power potential as one larger one will have the same spool as the larger one. You can find extreme examples of both; either two tiny instant-spool turbos or one huge turbo that takes till 5k rpm before the fun starts. Neither extreme makes one better than the other.

I've quite a few turbo cars over the past 15+ years - 5 turbo DSMs, two twin turbo Stealths, and my current Subaru. I also converted a 94 Supra from twin to single. It made 505 whp on pump gas with great drivability because we didn't pick some huge dyno-crushing turbo. It was meant for a daily driver and responded accordingly. 121-122 mph traps show it wasn't hurting up top either.

That same turbo would probably spool extremely quickly behind a Hemi and would yield plenty of top end power. Bigger isn't always better. No matter what the engine, a given amount of horsepower requires the same basic amount of air plus fuel; it's up to you how you get to that point.

 

I know that this is for a Hemi, how about us 4.7 guys?? Can we get good results with our motor too?? Will I have to upgrade my motor in any way or can it be left stock. I'm at about 50,000now. I like the thought about having a turbo that is truly a bolt-on and can be done by me and not worry to much. What are some of the performance #'s after the install?? Any better fuel mileage, I know at first it will suck because of wanting to get it "Spooled-up" sooner and the feel the power thing but later for on. Here's some other questions

1 Tranny issues??, 2. rearend issues, 3. tire issues i.e.traction? 4. smile factor?

Thanks All H-

 

they hemi crank dyno standards are with all accessories, hense net horsepower rating. When in the 70's and earlier, they dynoed, it was gross, just the engine with nothing on it.

Oh, and for the sts guys. If running a max of 7 psi, any estimates on the hp gain, and what about driving habits and the 5sp auto that comes with the hemi. do you have to do anything special like no boost on down shift, etc.

 

I made 267rwhp stock with exhaust and cai.

With 7lbs of boost, I made 419.xrwhp.

The important thing about driving is NOT to let it downshift while under boost. It will destroy the clutches in the trans. So you guessed it right, lOl.

Upshifts are no problem.

 

is there a way to reinforce the clutches, or is there a way to stop the boost for downshifts(or just let off the gas?)

 

That question is a little complicated to answer.

There is a trans solution. But you will have to send the truck or trans to the shop for them to modify the trans.

If you are wanting to downshift for extra rpm under boost, forget it without the upgraded trans.

And the rest of the answer would depend on the mph you are going at the time and what gear you were in.