Good point, Because the fact that diesels don't have spark plugs, the air flow dynamics are COMPLETELY different

 

I've always got hung up on the fact that a turbo is a huge exaust restriction, and superchargers hate restrictive exhausts. You could put a huge A/R housing on it, but then you run the risk of the supercharger being done and the turbo not being fully spooled yet. I think with a gas engine, you'd have crazy EGT's with twin charging without some sort of bypass valves or something.

 

The cool thing about compound system is a turbo would spool much quicker than it did without a SC because of the increase airflow provided by the blower at much lower RPM's. If a turbo hit max boost at 5K on itself, it's be realistic to think it'd spool in the high 3K's due to all the added airflow and exhaust gasses provided at lower RPM's by the SC.

 

I sure wouldn't say diesels make great off idle torque. It may look like it when they are dyno'd, but only when you just look at the chart. Take a diesel to the track and launch it off idle. You'd be lucky to get a 60' time of less than a 2.2-2.3. Until they come into boost there isn't much for power at all. The sequential turbo system works out very nice in the way of making very quick boost and yet still flow enough air to make the hp in the higher rpm (higher airflow demand). They are however more complicated and are considerably more prone to problems. As for running a supercharger with a turbo, you're just asking for more heat. This is the reason that no other companies do this. If you look at the famous Detroit diesel you'd see just how big of a blower they used just to keep the blower from being a restrition to the turbo. There is no best of both worlds. You either get the efficiency of a turbo with some lag or you get the parasitic drag of a blower. The only big way around this is alot of cubes. Then you have alot of power even when not in boost, unfortunatly with no fuel milage to match.

 

Nitrous and Turbo, great off line performance, and great top end. But there is that thing of getting greeeeedyyyyy on the bottle.
They even have progressive controllers to trim the nitrous back as the boost comes up.

The only way to put the hole compound thing to bed is for someone to do it. Post the results good or bad..

I think the chart shows nice low end. And lets face it; you can give up a little in the begining if you have a few hundred extra at the end.

Rick sorry but the thread looks like it took a turn.

 

It was so big because IT had to supply the air so the engine would run.


take a 408 with 8.0 scr. install a pt-88 turbo on it, make it build 20-25 psi of boost What are you IAT going to be?

Take the same 408 and turbo, install a Radix. Run the radix with the largest pully you can find so your boost would be 4-6 psi from that alone. Then the turbo would only have to build about 10-15 psi to hit you 25psi goal. What does the IATs of a pt-88 at 15 psi and a radix at 5 psi look like?

If some one would like to buy my 10-1 pistons off me, I'll gladly order 8-1's and put this to bed...

 

Get in line buster, I was here first!
I think you and I have an ideal system for trying this out in any case. Better than front mounts or pro-charged as seen in one recent application.

 

You have no traction though

 

If some one wants to loan me a Radix for a couple month, I will gladly test it on my new motor (9.25 to 1 forged ls1).

 

Brainstorm, How about adding a bypass circuit for the turbo into the intake plenum of the engine with a valve that is set to open once the supercharger is out of its efficient range. It would probably also be wise to install an electronically activated "slipper" clutch on the pulley of the super charger to de-couple/re-couple it from/to the serpentine belt without shocking the bearings and rotors.

To address EGT, set up a bypass circuit in the exhaust that activates on EGT, backpressure, and RPM of the motor. Just make sure there is a minimum flow of exhaust through the Turbo side to keep it spinning.

Just a few thoughts.