Forum for competition engine enthusiasts. RIP Guy Croft 09/11/2020 - This forum will continue both as a source of information and as a memorial to Guy.
Well I sent you some stuff through to show the theory behind where I am coming from, but what do you think to something like this?
The blue shows a sealed duct so the air is forced through the matrix. The inlet/outlet are at the same ends so easy to couple up to the turbo/plenum and you may get some boot space! Hmmm, maybe not after you have fitted your duct to remove the air...
It's very difficult as I have no dimensions to work to, but basically the intercooler you have has tubes which are far too long and a cross sectional area which is too small. It has to be bigger, but in the right areas.
When I was building my mid-engined kit-car (Shelsley T2), a rear-mounted intercooler with twin fans was a serious option, but not my final choice.
I intended to use a twin-pass intercooler (of similar size to yours) to ensure both inlet and outlet were on one side to make the plumbing easier. After a lot of deliberation, first fixing, mocking up etc... there were some fundamental issues that I deemed to make the option not viable. I decided that getting cold enough air to the intercooler was going to be next to impossible.
By adding the intercooler you are trying to make the engine more efficient by reducing the charge temperature to only put more load on the engine by using two 12" fans (say 25-30A draw off the alternator) and increasing the weight distributed to the rear by installing a heavy intercooler setup behind the rear wheels.
I opted for a large charge cooler setup (see attachments) which, although installed in the same position as the intercooler, the addition of 2nd radiator (lotus exige air-con rad.) at the front helped to balance the additional weight (plus the fans only run when the water temperature increases above a set level). The pump that I used is a Bosch item designed specifically for use as a change cooler pump, 18mm inlet/outlet on the pump with 1/2" heater hose for pipework. The pump inlet is only 6" from a header tank so pushes the water around the entire system. The 1/2" pipework works well as it is large enough diameter to have a good volume of water in the system but also reduced the likelyhood of airlocks. The system is completely sealed and the coolant never gets hot enough to vapourize so once it is bled there should be no issues. I haven't had any to date - when logging the air-temps at Donnington the other weekend they did not exceed 45deg C at 12psi boost.
Chris
Attachments
View of engine bay nearly finished with only the heat shield to add.
enginebay1.jpg (120.11 KiB) Viewed 38847 times
View of engine bay during installation (note: charge cooler pump on rear boot lip - not fitted yet!)
As Guy stated already, thank you to the contributors so far. Its great to see options coming out and to see how other people have dealt with or would deal with similar set ups.
I paid a visit to Phill yesterday to see how things were coming along, and the air flow is something we discussed quite a bit.
I mentioned the vent that I originally posted about in this thread, and he's advised that there would be little point. The aerodynamics of this car produce a low air pressure area behind the car. This is evident by the way they get filthiest at the back when it rains. As such, he said that the air would naturally be pulled through the core and out the back. The fans will be controlled by the ECU and only come on when intake temps reach a predetermined level. The fans them selves pass a huge amount of air so the shear volume that will be passing the core should be very capable of keeping the temps down, even when queueing for a drag run. I'm going to make up a vent blocking plate and send it up to phill along with a number of other parts he has asked me to source. I may in turn look at blocking the other side of the boot area off so that the air doesn't pass back over the other wheel arch into the engine bay. I think decisions like this will need to be made once the car is on the dyno and starting to make power.
This is how its currently sitting above the exhaust.
I'd be inclined to re-visit the charge cooler idea. Has the very real advantage, for short events, of your being able to ice up the system without risking C02 in the inlet tract – intercooler efficiencies of over 100% should be on the cards (briefly) as you can run the pump, see below, without running the engine and thus pre-cool the entire system prior to a run. A high mounted reservoir, decent bleed points, vacuum bleeding and – just an idea – a central heating pump (run off a 12v inverter, as in the Practical Performance Car V8 Transit ) should make it pretty reliable and, since the fabrication is already done, pretty cheap.
Otherwise, in the Mark Warner Street Turbocharging book is a turboed Mk.1 MR2 which I like a lot. The intercooler is mounted just below the engine cover (which it vents through, through backward pointing scoops), intake is via the underside of the car (taking full advantage of the high pressure to low pressure effect). Fans cool the intercooler while staging (it's a sprint car).
The I/C will be staying put for the time being. Mainly because other things require the money that it would take to change.
I've been speaking to a few people who run boot mounted I/C's and one recommendation is to wrap the silencers in Aluminium matting and tape. They said the cans stayed a lot cooler compared to without the matting. It seems a cheap method which could give quite good results so will be something I try soon.
Once thing that hasn't been mentioned yet is the lenght of your IC piping. Doesn't seem that bad considering what you are doing - plus your using lovely stainless pipes. I recall seeing a chap in Japan who had a front mounted Intercooler in his MR2 and the pipes went through the cabin into the front boot. Perhaps Guy could comment on the length of inlet tract between turbo and throttle, ideally should it be as short as possible to reduce lag. Maybe not as important for high boost/big turbo/anti-lag drag car applications.
Are you plannning on putting some vents into the actual boot lid? If not where is the air flow/feed going be coming from. Its fair to say that the fans should push air through the IC and the vent underneath will pull some out, but will it not get to a point where the air pressure inside the boot will drop (not exactly a vacuum but you know what I mean). I have noticed that you have cut a section out which goes into the engine bay though, are you going to seal this up? Would be much better venting clean air rather that air from around the engine (plus it'll get all dirty).
Nice project though. I used to have an MR2 myself.
Yes I made the decision to part out the car a few months ago. Now have a Mitsubishi Evo 8.
When you consider the length of the piping in that set up, it is no longer than that of a Front Mount Intercooler on things like the Nissan S14, Skyline, Mitsi Evo, Subaru Impreza's etc. I know of people who have run a similar set up on a stock turbo and they commented on the lack of noticable different over the standard Side Mount Intercooler. I think the speed that the pipework is pressurised at really can't be noticed without possibly electronically logging it.
The MR2 with the FMIC was a Pheonix Power car running some 800hp if I remember correctly. Insane set up, and completely unneccessary as proved by a recent 900hp UK MR2 which now holds the WR for 1/4mile (MR2 only) ar around 9seconds, but it was definately different I'll give them that!!
For me I'd not so much worry about the length but rather the number of bends and cl radius of them, that and diameter. Unless they are hugely long they'll fill up in a nano second when the turbo is pumping.