43 replies to this topic

[Bengie]

You seem to be spoiling for a row in something you know little about - if its good enought for colin blower with 30 years of racing, its good enough for us

oh just to add, the back of the car is a low pressure area - hence the reason for lift and need for a wing

Bollocks - I'm spoiling for a row because of the usual attitude of a few people on here that state things as if they are fact, when they might not be.

Don't forget that Colin blower's car has got no boot, and half the rear clam missing.

You aren't comparing eggs with eggs.

The back of the car may be low pressure, but what about the middle, where this mod has been done.


The orginal post was asking whether or not the water ingress kit would affect cooling much on a Stage 2 AMD VXT.

In my opinion it won't, because it doesn't cover the chimney heat vent, only the head, and therefore (especially on a VXT, not VXR with it's hybrid turbo) there is no need for unproven cosmetic mods.

My argument is, as I've said, not against the mod, but the misinformation that is bandied around.

[Bengie]

...perhaps I'll just cover them up again to save the arguements!!

The argument isn't about you, nor really about the vents.

You've had them put on, because you liked the way they looked, and because you thought they'd help cooling.

That's fine. What isn't fine is when people take that and say 'This helps cooling' without even testing it.

[Thorney]

At the risk of jumping in.....there is always this - PROVEN to drop engine bay temps



(I'm only trying to lighten the mood before anyone wants to jump on me)

On a serious point there are 2 schools of thought.

1. The VXT suffers from very high engine bay temps, this isn't too much of an issue as the engine was designed to run at high temps but start modding and the temps get higher so in effect ANY mod which reduces this issue is a positive.

2. Engine bay airflow is not as easy as people might think. The VX has a flat floor design with 3 vents placed in the under stray to vent air up and over the turbo, this air is then vented out through the engine bay cover (boot lid). By far the hotest place in the engine is round the turbo and manifold, I've even seen cars with melted mesh The rest of the engine bay is relatively cool, we've put temp sensors (called heat stickers) on a variety of places and the only place where it registered a reading was above the turbo - where in fact the sticker melted

Lotus and Vauxhall knew this so when they designed the VX Sprint they designed the high airflow bootlid to help drop temps. Simple concept - the heat comes from over the turbo so raise the air area above the turbo, raise this further into the airflow coming off the roof and you'll drop the temps (by their reckoning 8-10%) which is significant. All I've done is made it out of CF so its half the weight of even an standard VXT bootlid (and about 1/3 of the weight of the Sprint one) and widen the mesh by 70% to increase heat disipation further.

I actually like the look of the cuts Geoff has done on his car Would I do it? No, as I don't think it makes a 'meaningful' difference to heat drop (but thats not to override No.1) but then the CF bootlid is £700 odd so isn't cheap. Would these vents replace the bootlid in effect - no way but then its a cheaper way to at least try. Bengies 'chav' comment was direct but hardly violent, there are worse names called to people here all the time.

The GT car has a complete open clam (not just no boot, no anything underneath it at all) so the vents there would/could make a difference but Colin isn't allowed to use the Sprint bootlid design (wasn't a prodcution item) but he is allowed to cut extra cooling vents whereever he can. Seeing as the GT car has melted several exhausts and an ECU iirc then he'll do whatever he can to drop temps. Will the vents make a massive diff? Probably not (but more so on the GT car due the clam design) but are they worth doing from his perspective - yes, took about 10mins with a saw and some glue.

IMO in summary. If you like the look then do them, I've no idea how much it would all cost but you are hacking into a £1500 part (clam) so get it wrong and it'll need repairing and its hardly a mod that you can undo. I've no doubt they will do 'some' cooling on a road car but doubt it will be significant so leaves the mod is the 'cosmetic' group for me, thats not to say its not good, like I said I like the look but I personally wouldn't say it was a engine bay temp issue mod. Would there be a resale issue, especially if you're trading the car in? I've no idea but as Geoff says he's not selling any time soon I doubt he cares

[geofflowe]

I am aware of the debate over the mods and although i have not shown them here, I have done a couple more. All will be revealed on Saturday and one of them especially does introduce a significant amount of 'fresh air' in to the engine bay (this has been tested with an air gun - then at around 120mph). The other ones may or may not extract heat but the positioning would indicate they should do.

[kipper]

nail on the head - More air thru the IC, means a cooler charge

Cheeky, while at Palmer's VX day, we had a breif discussion on the installation of fans to force more air through the IC.

Would be interested to find out more.

There also seems to be a problem with the flow through the IC due to the proximity of the inner wheel arch. Have not looked yet but could the IC be moved forward to improve flow through it ?

In the German Opel Speedster project vents were cut into the wheel arches to improve flow through the IC. Perhaps they dont have as much muck on their roads as we do


Dave K

[Thorney]

nail on the head - More air thru the IC, means a cooler charge

Just noticed this, not sure what you mean mate?

A CC is water cooled, adding extra airflow into (notice I don't say through) will help but it can only cool air up to its flow rate (determined by its size and design). The stock IC is very impressive in this regard (after 19 odd goes Lotus couldn't improve on their own design any further) so no point upgrading.

Getting cleaner air to it will help but it won't be able to do any more with it.

A CC is an IC with a water jacket/pipes, so as the air passes over the vanes the water cools it much much more than just the vanes alone on an IC. Its the reason why CC are banned from most race series.

[Thorney]

the installation of fans to force more air through the IC.

This would help a little for when the car is stationary but I doubt would make much difference when on the move, the size fan needed to generate the level of pull would be enormous. Not tried though.

[kipper]

John, I think its a 'cooler charge' not a charge cooler

[cheeky_chops]

there is two distictly different issues here...

charge temp or inlet temp - the temperature between the IC and turbo
engine bay temp - the temp around the engine

Charge temp: if you have little air flowing thru the IC, it wont cool the air enough. A 70c temp is high (stage 2), 38c is optimum. A 10c decrease in temp will increase power by 2% (denser air). If you can get more air "thru" the IC then it will be more efficent. Geoffs mod SHOULD allow more air/heat to dissapate as it is directly above the hot IC (chimney effect)

Engine bay temp - things will melt if it gets too hot. Also, heat soak of air filter pipe, intercooler etc makes it more difficult to get cold dense air into the engine. Thorneys lid WILL cool the engine bay down

Noble has a similar problem, infact worse as its behind a hot engine - http://www.pistonhea...26&f=26&h=0&p=1

There is no doubt, a front mounted charge cooler is ideal, but i dont have £1500 to spend - hence i will be looking at part of the Noble solution to increase my std IC's efficency. I dont expect a massive change, but knocking 10c off the inlet temp would be great

[cheeky_chops]

the installation of fans to force more air through the IC.

This would help a little for when the car is stationary but I doubt would make much difference when on the move, the size fan needed to generate the level of pull would be enormous. Not tried though.

I have only spend a few hours looking on the net so far, still lots of questions

Has anyone got the dimensions for a std IC??
Pressure drop?

[Thorney]

I fail to see how having more air (assuming thats what you think will happen if you vent above the IC) will actually drop air intake temps, the air isn't in the IC long enough to cool anymore regardless of how much air you put around it so I very much doubt any extra cooling there will make any difference at all to air intake temps. How the IC works is air flowing through it at high speed is cooled over the vanes, having more air around these vanes I guess will help but certainly not enough to make any meaningful difference to temperature as it passes accross. The CC works by making these vanes much much colder than the surrounding air so whilst the air isn't flwoing any faster over them the ambient temperature they pass by is much lower hence resulting in lower intake temps. Don't get me wrong, the CC isn't cheap and anything you can do to help drop air intake temps is laudable and I would encourage it for anyone but I doubt you'll get near the effect of a CC set up.

[waverunner]

the installation of fans to force more air through the IC.

This would help a little for when the car is stationary but I doubt would make much difference when on the move, the size fan needed to generate the level of pull would be enormous. Not tried though.

This just reminded me that my MX5 turbo had a fan attached to the IC. It ran totally independantly of the fan behind the rad. Never gave it much thought at the time. I've not a clue why it was there. Brodie Brittan Racing did the work on the car so there must have been some logic behind it.

[cheeky_chops]

I fail to see how having more air (assuming thats what you think will happen if you vent above the IC) will actually drop air intake temps, the air isn't in the IC long enough to cool anymore regardless of how much air you put around it so I very much doubt any extra cooling there will make any difference at all to air intake temps.

The physics seem quite simple the more cold air you pass over a warm object, the quicker the heat will be removed relative to the density of the object and the temp of the air passed over it. So, passing more air thru the IC will increase its efficency towards it maximum. You can do that by fan, cutting open the clam, making the ear bigger or cooling the air - as you say, it all helps.

I doubt you'll get near the effect of a CC set up.

As i said i wont get anywhere near a CC - water has a far higher themal capacity to remove heat. If i knock 10c of the inlet temp i will be happy

[Thorney]

Fair enough Although 10c is massive in terms of a drop I'd be happy with 1-2c if that.

[kipper]

Here's an experiment. Borrow or steal your wife's/girfriends/Mothers hair drier or driers The more the better. Get the engine up to temperature. Install some Wahl temp-plates or simmilar on the rubber piping from the IC to the inlet manifold. Record the temps. Re-do with driers on, cold of course Then face wrath of fairer sex for oil stained drier. Having said that heat loss by convection is directly proportional to the excess temperature, hence more power generally in winter. However, unsure as to the extra lost by forced convection

[plotloss]

Is cooling a real issue on the stage 2's? Are we talking temps that need care etc on normal driving, spirited or track days? Dont mean to hijack. more curious and it certaintly seems to spark debate as a topic!

[Thorney]

Is cooling a real issue on the stage 2's?

Are we talking temps that need care etc on normal driving, spirited or track days?

Dont mean to hijack. more curious and it certaintly seems to spark debate as a topic!

In a word...yes. Its not an OMG I must drive like a girl level but more of one of mechanical sympathy. The three rules I tend to run the engine by on this:

1. Cool down. Always let the engine run on idle for a while after driving hard, ideally a few miles of gentle driving after a hard run is good.

2. Heat soak. On track days, hard drives in hot weather pop the boot lid to help drop the engine bay temps after hard use.

3. Consistent useage. If you're sitting in traffic and getting hot, resist the temptatation to use all the power on first acceleration away to let the airflow cool the engine before using it fully.

I make it sound worse than it is. Of couse a with CC and bootlid I can drive mine how I want

[Bengie]

I make it sound worse than it is. Of couse a with CC and bootlid I can drive mine how I want

Like a girl.

[plotloss]

Is cooling a real issue on the stage 2's?

Are we talking temps that need care etc on normal driving, spirited or track days?

Dont mean to hijack. more curious and it certaintly seems to spark debate as a topic!

In a word...yes. Its not an OMG I must drive like a girl level but more of one of mechanical sympathy. The three rules I tend to run the engine by on this:

1. Cool down. Always let the engine run on idle for a while after driving hard, ideally a few miles of gentle driving after a hard run is good.

2. Heat soak. On track days, hard drives in hot weather pop the boot lid to help drop the engine bay temps after hard use.

3. Consistent useage. If you're sitting in traffic and getting hot, resist the temptatation to use all the power on first acceleration away to let the airflow cool the engine before using it fully.

I make it sound worse than it is. Of couse a with CC and bootlid I can drive mine how I want

Thanks John.

I used to run TVR's and with them its always a one eye on the guage and one eye on the road affair.

So just treat it like a 1980's Integrale Turbo and it'll be fine yes?

You mentioned the other day about intake temps as well, will your 3 tips for mechanical sympathy manage any resultant issues in this area?

Or I suppose I could just go Stage 3 and get the CC fitted.

Hmmmn tough choice

[MartinS]

Can someone just post a picture, so we can see what all the daft argueing is about. Martin S