Compound Boost/Twin turbo+Supercharger

[anton28]

So I noticed that GT40 and 03/04 Cobra guys run Twin turbos with their blowers. Now I know the ups and downs of such a set up so lets not make this a debate as every set up out there, either TT or supercharged, has its ups and downs. I just wanted to know why we haven't seen a set up like this on a viper. How sick would a Roe car along with the Twin Turbos be? Not to mention how sick it will look under the hood! Roe blower with the turbo intake pipes along with two blow off valves.

 

[cyaford]

The GT500s are also doing the combo. I think the problem is you'll be limited in how much power you can put down. At some point, the Roots would be a restriction to the turbos.

 

[Seb]

probably because of cost factor. The benefit is instant response with plenty of top end mass flow.

 

[BOTTLEFED]

The Roe would restrict air flow up top and just be adding heat
Down low it would be good, but the turbo could be adding too much backpressure
So they may make a lot of power, but the efficiency would be atrocious since they would be fighting each other along the way
I don't think there is a problem with not making enough power on a TT setup

 

[Ricketts]

With the Roe it would just be a restrict/heat maker. The big flaw with the Roe in comparison to the KB'd, Whippled Cobra's GT500's etc is the fact the Roe is non-intercooled.

 

[Russ M]

A properly sized turbo on on 8L motor and you have more low end torque than you know what to do with.

Vipers already have serious traction issues because of the low end torque, the only thing a Roe will give you is a bump in torque up to say 2k rpm. And even then we are not talking very big improvements.

My turbo car has 400lb torque at 1500rpm to the wheels 460 or so at 2k and 500 at 2.5k. After that turbo's come on to full boost, and you start roasting R compound tires at 100+mph. This is also on a dyno, on the street power comes in considerably sooner due to the load.

 

[anton28]

All good points guys! The ROE/KB unit that Roe sells does have heat issues. That i know because it had one as well. Now if someone would retrofit the new KB 2.8H liquid cooled Mammoth unit on to a viper!!!!

 

[CWhiteRun]

Now if someone would retrofit the new KB 2.8H liquid cooled Mammoth unit on to a viper!!!!

There are a few people attempting this...but of course they want it to be super secret. I would give it a whack...but I'm lucky just to have a 2.4L Roe.

...and regarding the compounding boost idea is a great one if it's USEABLE. Our cars would be completely useless with that much power. I read a few years ago that VW has been working on bringing a setup like that to the marketplace in the form of a 1.4L four cylinder. Here's the story ----> The Turbo- and Supercharged Car | Popular Science

 

[EllowViper]

2.8H LC just maintains even heat range across the rotors on the blower...not an intercooler. Meant to control thermal expansion from-to-back on the rotors allowing tigher & more controlled lobe clearances. As most realize, the rear of the blower (cold air side) expands less that the hot (discharge) side of the blower. So the rotors experience heat expansion at differing points on the rotor. The LC accounts for this temp variance allowing the rotors to maintain front-to-back clearances better than the non LC models. Even if the ROE was intercooled, the 2.8 and smaller really do not put out that much boost as compared to a turbo. Yes..any intercooling would be better than the current situation I agree. My 2.8H with the smallest possible pulley is hitting 14 or so PSI and I'm spinning the piss out of it. If we were able to use the 3.6 and get the boost into the 20's, then the benefits of intercooling whould be greater. Actually I would postulate we couln't run that much boost without intercooling. Also, we don't have a drive belt that will support anything bigger than the 2.8 either. I'm leaving all kinds of belt dust on the assessories as it is and my tensioner does quite a dance when the blower starts pulling. The Mustang guys are running more ribs on a bigger pulley and are still having slippage issues.

 

[anton28]

2.8H LC just maintains even heat range across the rotors on the blower...not an intercooler. Meant to control thermal expansion from-to-back on the rotors allowing tigher & more controlled lobe clearances. As most realize, the rear of the blower (cold air side) expands less that the hot (discharge) side of the blower. So the rotors experience heat expansion at differing points on the rotor. The LC accounts for this temp variance allowing the rotors to maintain front-to-back clearances better than the non LC models. Even if the ROE was intercooled, the 2.8 and smaller really do not put out that much boost as compared to a turbo. Yes..any intercooling would be better than the current situation I agree. My 2.8H with the smallest possible pulley is hitting 14 or so PSI and I'm spinning the piss out of it. If we were able to use the 3.6 and get the boost into the 20's, then the benefits of intercooling whould be greater. Actually I would postulate we couln't run that much boost without intercooling. Also, we don't have a drive belt that will support anything bigger than the 2.8 either. I'm leaving all kinds of belt dust on the assessories as it is and my tensioner does quite a dance when the blower starts pulling. The Mustang guys are running more ribs on a bigger pulley and are still having slippage issues.

What 3.6 unit are you referring too? If KB, i didnt even know they had one in production that size. I know they are working on a set up but didnt know it was already for sale. So you are already running the 2.8 on your viper? Who did the conversion?

 

[EllowViper]

3.6 won't fit without extensive mods and fabrication. Prett slick blower however. The 2.8 is a direct bolt on replacement (upgrade I suppose). I got mine directly from KB but Sean Roe has them for sale as well. I posted the 2.8 install on the forum a while ago. DIY.

 

[RTTTTed]

Since TTs can build a lot more power than is useable adding is unnecessary.

I owned a Detroit Diesel called a Silver 92. It was Turbo'd and had a Roots blower on it. Terrible for maintenance and unreliable. Big power and terrible mileage. They were 2 stroke engines.

I saw an Oldmobile at "Hot Rod Supercruise West" in Vancouver wash. The car was supposed to be just as fast as if the turbos weren't there. Near as I remember the turbo was plumbed into the top of the blower housing case. Probably a fake.

With Roots blowers building as much as the dragsters are running now (5-7,000hp) I can't see the point of double systems ... except for looks.

Ted