1268 replies to this topic

[Exmantaa]

I've also seen plots of heat echoes through w2a setups Thing is, it's not meant to be an instantaneous 1:1 transfer process. The principle is to have an instant heatsink (water), and the front heat exchanger is designed to then shed this over an extended period. Having echoes circulating after a single big heat spikes is entirely normal 'Extended period' is of course a bit subjective. For eg, if you require a system that sheds heat on an unrelenting / constant basis, you don't have time off load for the front exchanger to 'catch up'... but that's pretty rare (boats etc running at constant rpm/load) 150L /min is enormous! My reckon on repurposing the heater lines was twofold: 1- save weight of 2 complete water circuits (?10kg) 2- I wanted to ditch the 'flap' heater control and run the core on a valve (can't do that if the heater core flow is a part of the thermostat circuit)

 

You can do #2 easily by using a "bypass" valve with the existing tubing. If I'm correct the updated Fezzasus heaers use this system.

 

For the rest you simply need as much cooling as you can get/afford.  

[Doctor Ed]

True The whole 'multiple sets of lines' thing bugs me tho. It's not very elegant

[Arno]

If you don't need/want to keep the boot/luggage space in the car then IMHO it's also quite doable to go '911 turbo' style and fit air-air intercooler(s) in the back area with sufficient mods to the clam, ducting/shrouding and perhaps some hefty (puller) fans to add more airflow.
 
Eg:
 


Will it be less complicated? With sufficient mods to clams and getting all ducting worked out to maximise the airflow across the coolers perhaps not.. Is it different? Yes

 

Bye, Arno.

[Mopeytitan]

Now that's an idea!! Would make rear clam cutouts actually useful

[Doctor Ed]

except the vx doesnt have any space in the rear quater panel as above, and rear calm cutout are next to useless from a flow perspective. i did the maths on a fan driven rear A2A cooler, and it would work, but theres several things against it, primarily the bulk and rearward position of it all, but as im planning some proper big diffuser tunnels through the back, venting becomes a significant issue. plus the PWR stuff popped up at a mates workshop, and for 200 whos saying no?

[Mangham54]

except the vx doesnt have any space in the rear quater panel as above, and rear calm cutout are next to useless from a flow perspective. i did the maths on a fan driven rear A2A cooler, and it would work, but theres several things against it, primarily the bulk and rearward position of it all, but as im planning some proper big diffuser tunnels through the back, venting becomes a significant issue. plus the PWR stuff popped up at a mates workshop, and for 200 whos saying no?

 

 What's in the rear quarter panel? I thought I recall a bit of space, as i spent ages clearing a load of crap out of it.

[Doctor Ed]

youd want the exit of the IC to be in an area of flow, the 911 above has it behind the rear wheel arch. the vx220 has no 'behind rear wheel arch', the closest would be at the back of the car, which is an aerodynamic dead zone, so all flow would need to be fan-driven. youd get SFA passive flow

[Winstar]

youd want the exit of the IC to be in an area of flow, the 911 above has it behind the rear wheel arch. the vx220 has no 'behind rear wheel arch', the closest would be at the back of the car, which is an aerodynamic dead zone, so all flow would need to be fan-driven. youd get SFA passive flow

Not quite true as the rear of a car is a negative pressure zone so can be used to suck air flow through from the side/front if the exit is in the right place. Anyway read the Barcelona 24 prep blog for all you need to know on cooling high power vx/lotus http://www.hofmanns..../archive/201108

[Doctor Ed]

from what ive experienced on other square backed cars is that the flat back is far from a neg pressure zone, and rather a whirlpool off eddies... so wont push nor pull air, and relying soley on the pressure differential from the side scoop to drive through a core or 2... well, i just cant see it working well. you could pump (with fans) into the air at the back of the car without having to force it uphill, so that would be a feasible solution and net good rates. could equally draw from the rear of the car and pump into the deadzone behind the rear window or i could just buy the W2A that my mate rocked up with edit - ps, awesome link, thanks

Edited by ed.oates, 04 May 2016 - 01:51 PM.

[Nev]

W2A (with large front mounted pre-rad) wins hands down in any sort of serious demand situation, as I'm sure you know already

 

Also, remember much of the weight of a W2A is in the front of the car, which helps with handling considerably in my experience (I have 42% front axle weight with me in the driving seat, which is good high % for a VX).

 

Just look at the problems the SC'ed kids get in with IATs hitting 50 to 100 degrees C, all due to a lack of suitable charge cooling and it's clear that good charge cooling is vital as soon as you hit a PR of 1:2

Edited by Nev, 04 May 2016 - 02:16 PM.

[Doctor Ed]

that, and an M62 beyond a PR of 1.5 just turns into a massive heat pump. easily +40degC difference between 5psi and 10psi from an M62

[Nev]

I push 10 PSI out of my turbo (most of the time) and have no IAT issues what so ever as I am on the bottom left of the pressure map island and have a good W2A intercooler setup. Even on a sustained flat out blast for a couple of minutess the IATs are usually no more than 8 degrees above ambient on a cool day and 12 degrees above ambient on a hot day. This is a key advatage of going for a correctly specced boost pump (whether it be turbo or supercharger). As I am sure we all know by now both the K04 turbo and M62 (at circa 300 BHP) are both thrashing on the far top right of the pressure island.

Edited by Nev, 04 May 2016 - 02:34 PM.

[Doctor Ed]

[Nev]

Gawd, how many plates in that clutch?? 3 or 4?

 

Edited by Nev, 05 May 2016 - 09:45 PM.

[Doctor Ed]

Nah, they're just spare intermediates. Will set it up as a twin cerametallic

[Doctor Ed]

notes from the weekend... heater piping is 14mm ID - it flares out in the engine bay, but the bulk of the piping, and the connections at the front are all 16mm OD / 14mm ID. no way that is going to flow much over such long lengths. based on water flow calcs, assuming only a few psi pushing things along, an idea scenario would have 30-35mm piping. i know thats exactly what was mentioned here previously, but I came up with that same number myself the round-about way after trying to figure what kind of flow i needed for cooling etc. nice to see the numbers kindve match really. still 30mm anything is a big chunk of tubing. the barrel core, and the front exchanger are both 19mm fittings. so what i was thinking was: - use an Davies Craig EWP115 pump, which has 38mm standard fittings. mount the pump at the back of the sill, infront of the rear wheel arch. - run 38mm hose in the sill front to back, and from the pump to Barrel reduce it to 19mm, and at the front to the exchanger, also reduce it 19mm. that way I have only short lengths at a reduced ID, and the long runs from front to back are big open pipe. its not absolutley ideal, but its a neat compromise. 19mm hose in 'work areas' is manageable, and im taking at least some advantage of the 38mm pump fittings we'll see how that goes next up, fixing the front clam. ok, yeah, fiberglass repair work sucks dick. started with a clam in 2 pieces, ended the weekend with one big piece. so progress the front hood!?! wtf, how does that thing manage to weigh so much?! angle grinder is coming out today (after my second coffee). hood hinge along is 1.2kgs. im ditching the latch/catch mechanism (mines busted anyway) and will simply use 6 Dzus fasteners to keep it in position on the front hood, what an absolute abortion as far as airflow goes! massive flat 'bridge' sitting in the middle of the flowstream, with no air guide/spoiler to help. and to make matters worse, in the middle at the back is a big cutout for tool access for the latch mechanism. its like a massive windsock. *facepalm*. cant do too much with it, but will try and add a splitter/spoiler to guide the flow to the sides a bit (i did consider just chopping it out, but it does look a little dumb without that bridge in place)

Edited by ed.oates, 09 May 2016 - 08:23 AM.

[Doctor Ed]

I should also add, my heater box is fcuked. the core is fcuked. the resister pack is fcuked.

motor runs nicely though 

after looking at exactly 1061 different heater core diagrams, Ive bought a Volvo 940 core, which with a bit of gentle persuasion should fit exactly inside the box (plus minus some foam/sikaflex). Ill run this on a cable operated bypass valve. should go ok. PS, thanks to the guys on the forum, who posted the resister specs. helped a heap. I order two ceramic 10W audio resistors (48x10x10mm) in 1.0ohm and 2.2ohm to solder in, in place of the melted, corroded, destroyed ones
 

Edited by ed.oates, 09 May 2016 - 08:35 AM.

[techieboy]

You need an FLD'd bonnet

[Doctor Ed]

yeah i dont know if it needs a hole/vent so much, it just needs to 'not be a brick wall' on the underside. vent on FLD's does look nice though!

[Doctor Ed]

fyi, pre angle grinder the front hood weighs 6.5kg