The Superboxer, a new heart for the Silver Bullet

[silverbullet]

My recent work on a fan-assisted wbx oil cooler kit for Pete's 2500 build http://forum.club8090.co.uk/viewtopic.p ... 9#p8077589" onclick="window.open(this.href);return false;
(and subsequent engines) has made me realize that a mirror-image setup for the rhs could work really well as a radiator for the chargecoolers...

[DSM]

I'm working on a prototype rad for the KO3 turbo using a Bosch 002 pump at this very moment. Any idea how much heat you need to dump?

Duncan.

[silverbullet]

No idea. The chargecoolers are from a 400hp Jaguar AJ-V8 that uses a pretty inefficient Eaton M112
The Opcon 2076 puts a lot less heat into the incoming charge, I have some graphs somewhere but ▲T data is thin on the ground.

[DSM]

Ok Ian. This is my area of expertise . For step 1 if we can estimate the maximum air flow and the pressure increase through the supercharger and the starting air temperature we can calculate the heat produced. An allowance needs to be made for the compressor efficiency as this will add heat as well ( this should be in the graphs or data you have ). Decide on an acceptable charge air temperature required and we have a duty in Kw.
For step 2 decide on the pump and glycol concentration and the space available for the radiator.
Step 3 would be maximum ambient temperature ( crawling on the M25 on a hot day for instance) then the surface required and airflow needed is deducted.
As an example the K03 at 5psi boost will need to have around 2.65Kw dissipated to keep the charge air below the maximum 50C in a 35C ambient.

[silverbullet]

I hoped you would say that!
I had guessed at a similar approach. I know how much the Jag coolers are good for, so that should give an idea of their air flow capacity (more than I need)
Working back from engine capacity and boost ratio etc and then see if a 50mm thick, 25 row 235 matrix will be enough at an acceptable pump rate.
I will dig out what data I have found.
Thanks!

[DSM]

Brain on standby! I already have the performance curves for all the common automotive pumps for my own project. Could you send any data files to my work email please (if you deleted it pm me).
I'm trying to imagine the sound of a supercharged wbx, it will turn heads.

[silverbullet]

Good man! Here are the numbers I have from the ground up.
It will have to be based on a 2.1 for its favourable rod ratio, 137/76 makes for 1.8:1 but means using a version of the messy MV piston to keep the static CR sensible. Hey ho.

So with an engine capacity, blower displacement and a max continuous rpm limit of 6000 for the engine, 15000 for the blower that will give an idea of max boost ratio if it is driven at 2.5 times crank speed.

The only Opcon Autorotor graphs that I found online after a good bit of google mining were for the slightly larger OA 2087 whereas I have the smaller 2076 but I do have basic data for it:
0.76litre per rev, 175 (possibly 190, slightly ambiguous) litre/sec .
Max airflow at 1 bar suction, 2bar (!) discharge and 2.0 pressure ratio gives a pretty constant discharge temp of 105*C with a peak of 110 @ 15000 rpm
Recommended for engines up to 180kw (no mention of chargecooling so is that direct?)

This is as much as I know, other than relaizing that it will be going UN-1 because I think it will shred an 094 transmission!

[silverbullet]

Google "opcon autorotor" and there is a 4-page brochure pdf download at http://www.not2fast.com" onclick="window.open(this.href);return false; that has a few performance graphs.

[silverbullet]

I pulled this boost calculation example from a built thread on the samba, using a Toyota SC12 (Rootes type blower) on a 2.1 wbx:

In order to determine the boost psi, we have to do the following:

To choose a setup you need to know :

1. Engine capacity 2.2
2. Maximum engine speed you will be using. 5500rpm
3. Boost level desired 6-8 psi

FIRST CALCULATION (Engine Litres/min @ 0 Psi )
Multiply engine capacity (in litres) times maximum engine Rpm. E.g. 2.2 litres x 5500 rpm = 12100 litres/minute. Divide this figure by two as engine only fills every second stroke.
12100/2 = 6050 litres/min.
This is the engines air requirements in litres/minute at 0 Psi boost.

SECOND CALCULATION (boost ratio)
Add the boost pressure desired (6 Psi) for the engine to 14.7 Psi (atmospheric pressure).
(6 psi boost desired +14.7 =20.7 psi)
Divide this answer by 14.7 and this gives the boost pressure ratio.
(20.7/14.7=1.408)
This is the boost pressure ratio above atmospheric pressure.

THIRD CALCULATION (Actual air requirements @ desired boost)
Multiply the boost ratio by the litres/minute obtained for 0 Psi and you get the actual air requirements in Litres/min for the engine at that boost. In our example this is 6050 litres/min X 1.408 = 8518.4 litres/min for 6 Psi boost.
To decide on the correct size of supercharger you need to know :-
1. The swept volume per revolution of the supercharger. ( SC12- 1.2 L/rev)
2. The maximum continuous safe operating speed for the supercharger. (Toyota SC12 11000 rpm??)
3. The maximum pressure that can be safely produced by the supercharger continuously. (Eaton M62 12 psi, SC14 10-12Psi)

FORTH CALCULATION (Supercharger rotor speed)
Divide the desired air flow (8518.4 L/min) by the swept volume of the supercharger (SC12 from the is 1.2 litres per revolution). This will tell you the maximum speed the supercharger rotors must be run at to produce the volume required.
8518.4/1.2 litres = 7099 rpm for the SC12 well within its capabilities.

FIFTH CALCULATION (Pulley size ratio)
Divide the rotor Rpm by maximum desired engine rpm to get the drive ratio of the pulleys. For an SC12 producing 6 lbs of boost in this application, the supercharger pulley ratio is
7099 /5500 rpm = say 1.3:1

[DSM]

Right! First stab at what is required; I read through the data and as you found it is not specific enough to give a definitive solution.
If we assume therefore at maximum rpm we have a flow of 190l/s at 2bar boost leaving at 105C then for every 10C you wish to cool this air you need to reject 3.5kw.
To home in on what is required we need to know the maximum boost allowed and the desired inlet manifold temperature.

I also looked at the Mocal data sheets and they show performance for oil but not water. Do you have anything?

The Bosch 002 pump will flow 20l/m against 30kpa and I believe this is the same pump that Jaguar used. There is an 010 variant that flows 25l/m and was used on the AMG turbo engines but is stupid money if you can find one.

[DSM]

I was writing when you posted that. So we can now home in on the boost level and flow rate required and I think we still have to assume the compressor discharge temperature does not exceed 110C for a 21C ambient as we have no better data.
So to recap if you can tell me the maximum boost and flow rate and ideal inlet temperature we can finish step 1

[silverbullet]

I found a peak air flow/hp calculator here http://www.mk5cortinaestate.co.uk/calculator3.php" onclick="window.open(this.href);return false; which indicates that a 2100cc engine at 12psi boost and at 6000rpm* would require 191 litre/second (and potentially make 269 crank HP), i.e. that will max out the blower discharge flow, so that's the ceiling.

*or 13 psi at 5800

[silverbullet]

PS I could give Mocal a call and ask what their convectors perform like with water/glycol, will have to be this afternoon as I have a Speed Awareness course to attend in an hour

PPS The 8" fan is rated at 200 litres/sec of air (not terribly useful what the Mocal cooler specs are all based on air flow velocity and Watts per tube per degree C) I do have a small anemometer so maybe the best thing to do is to build up a fan & enclosure, then measure the air flow rate using a 25 row cooler, because I have one to hand?

[silverbullet]

Trying to get a handle on how much air & heat the original XJR V8 cooler setup could handle, a 4 litre 400PS at 5800 seems to require 285 litre/sec @ 7psi boost, but again we would be guessing at what Jaguar considered an acceptable inlet charge temp (and how much over-capacity there is in the system)
Too many unknowns!!!

But this might be useful in getting a ▲T for the Eaton M112
http://www.capa.com.au/eaton_mp112_4th.htm" onclick="window.open(this.href);return false;

Looks like circa 180F at its upper rpm limit for 7-8 psi boost?
E D I T: so that is 100*C differential at far less boost than the Opcon, that is running faster!

[silverbullet]

Quick bit of arithmetic:

(2100cc x 5800 rpm) /2 = 6090 litre/min

12 psi boost → (14.5 + 12) / 14.5 = 1.83 boost ratio

6090 x 1.83 = 11145 litre/min air required

11145/0.76 litre per rev → 14664rpm blower max speed. 15k max continuous so thats ok.

14664/5800 → 2.53 blower drive ratio. It has a 76mm Polyvee drive pulley iirc so would ideally need a 192mm. I just happen to have a 185mm. Close enough!