A way to get more air to the radiator?

[hurststeve]

The S cooling system is marginal, we all know that. Has anybody thought about making holes in the underside of the front of the bonnet, in that flat plane that extends almost to the bottom of the radiator?

Seems to me that might provide quite a bit more air flow, as the forward sloping radiator sort of leans over that bit of the bonnet. I don't think it's particularly structural, but that could be overcome with metal stiffeners anyway.

[Boosted LS1]

If you can increase exit area then more air will enter the radiator. Can the outflowing air be controlled in a better way?

[GreenV8S]

hurststeve said:

The S cooling system is marginal, we all know that. Has anybody thought about making holes in the underside of the front of the bonnet, in that flat plane that extends almost to the bottom of the radiator?

Seems to me that might provide quite a bit more air flow, as the forward sloping radiator sort of leans over that bit of the bonnet. I don't think it's particularly structural, but that could be overcome with metal stiffeners anyway.

I think you're looking in the wrong area. You should have massively excessive air flow at speed. Where it gets marginal is low speed/stationary cooling, and the main problem here is hot air recirculation. You can address that by ducting the front of the rad out to the grill.

[trackcar]

Never had any trouble with my S cooling at all .. not even now at 300hp! I think if you're struggling you maybe have a underlying problem that needs addressing? Is your rad old and silted and many of the heat-sink fins missing? Would it benefit from a recore?

[hurststeve]

Hmm. I can see that getting better outflow would be best, but short of cutting slots in the top of the bonnet I don't see a good way to achieve that. (I've taken the seal off the back edge of the bonnet which will have some effect I suppose.)

Ducting would reduce recirculation, yes. Something to ponder.

(PS. When posting, how do you do that thing where you quote a previous post and it comes up in a box?)

[hurststeve]

Radiator is new. Two electric fans are fitted. And to be honest it all seems to work, but the fans come on more than I'd expect in a "normal" car. We haven't had any proper hot weather yet but it doesn't seem to take much, once it's up to temperature, for the fan to switch on. Perhaps I'm just worrying too much - it goes off again too so something must be right.

[hurststeve]

Forget my earlier PS. Just figured it out!

[Boosted LS1]

hurststeve said:

Hmm. I can see that getting better outflow would be best, but short of cutting slots in the top of the bonnet I don't see a good way to achieve that. (I've taken the seal off the back edge of the bonnet which will have some effect I suppose.)

Ducting would reduce recirculation, yes.

With most cars the centre of the bonnet is a high pressure region but the outside corners may be low pressure so make good exit points. You can use wool tufts to see what the air does. Also you can duct air under the car and even fit a spoiler but that's maybe a little OTT.

[hurststeve]

Well, I've gone off the idea of holes in the bottom of the bonnet now. After wandering around outside a bit I'm pretty sure that (without the fans on) the holes would cause air to spill out rather than go in, thus probably reducing the flow to the rad. (Unless a scoop was fitted......)

Must remember to wander around before posting.

[trackcar]

you want to put that seal back on the trailing edge of the bonnet, it's an area of high pressure not low pressure and won't be helping .. most of the air goes under the car and through the transmission tunnel.

[geoffn]

I am with Trackcar on this, I have never had a problem with the cooling no matter what the ambient, cooling fan comes on when I expect, stationary or slow moving, and goes off as soon as I am on the move. I refurbished the system not so long ago, backflushed etc and replaced all the hoses.