Hi

 

I am wondering about buying some hood vents. (GTR vents) I have a problem that the engine gets a bit hot when the weather is warm.

 

I don't have the platsic shield under the engine anymore. Could this cause the hot engine problem that the hot air gets pressed up during driving?

What's going on here, a 'warm engine temperature issues thread' and Vods hasn't posted a reply

What's going on here, a 'warm engine temperature issues thread' and Vods hasn't posted a reply

 

because i find engines are usually warm when they are running.

 

though not enough info to really give a good answer to it. could be a number of things.

shouldnt have to put vents in they run hot but they like it,, mine sits in this heat in traffic just fine temp gauge never moves

shouldnt have to put vents in they run hot but they like it,, mine sits in this heat in traffic just fine temp gauge never moves

 

The 300zx OEM temp gauge only has 3 settings, cold, drivable and blown head gasket.

 

You would be better of getting a aftermarket temp gauge to figure out what is actually happening.

Bonnet spacers would let you dump some heat.

 

No need to chop anything up that way.

 

Take them out when the weather turns again.

 

Vents and spacers can mess your cooling up, cooling us done by airflow, changing airflow with vents etc can mean air sits in bay for longer, just find why your having heat issues and not mask it

Bonnet spacers would let you dump some heat.

 

No need to chop anything up that way.

 

Take them out when the weather turns again.

 

 

 

I'm 99.9% certain that bonnet spacers have the opposite effect (although common sense tells you what they should do) they actually hinder hot air extraction from the engine bay due to the low pressure area at the base of the windscreen

Vents and spacers can mess your cooling up, cooling us done by airflow, changing airflow with vents etc can mean air sits in bay for longer, just find why your having heat issues and not mask it

 

?

 

not sure how you think air circulates inside an engine bay, but if the heat has no where to go (stock z32) then heat builds up, Vents do not interrupt the flow of air, hot air rises, putting vents on the bonnet aid cooling as the air can escape, it also aids airflow as the air has somewhere TO go, hence the reason why people raise the rear of the bonnet in hot countries.

 

The z32 coolant system is quite sensitive to not being well maintained and the design is actually one of the most annoying aspects when modifying your car. I would actually class a upgraded radiator as a must when going anything over stock HP as more HP means more heat is being generated.

 

With a fully functioning cooling system with the correct engine covers, the air comes in the front, past the Oil cooler (if its there) past the A/C fan, through the A/C radiator, sucked through the coolant radiator, past the Vacious fan, then blown over the engine, there is a small port for the hot air to escape on the top seem where the bonnet meets the rear seal up by the battery, the rest of the air is released via the side's out of the wheel arches, and under the car. which to be honest isn't optimal, you have a large hot air pocket at the top of the engine bay between the bonnet and the plenum that sits at a constant temp of hot moving air as the fan blows it over.

 

If you add vents here, it gives the hot air that accumulates here a means of escape, Aids the cooling and actually gets rid of stalled air in the system.

 

If the clutch is working correctly on your vacious fan, there is a hell of a lot of wind movement, enough to cool the engine effectively IF the rest of the system is working as intended.

I'm 99.9% certain that bonnet spacers have the opposite effect (although common sense tells you what they should do) they actually hinder hot air extraction from the engine bay due to the low pressure area at the base of the windscreen

 

Ive got mine raised, trust me when driving that hot air does move over the top of the car, you can feel it if you put your hand up with the roof off.

 

If that was the case, the GT40 wouldn't have the radiators in its bonnet the way it does, there is sufficient turbulence there to move that air away from the windscreen cowl and wipes/

it's a high pressure area when the car is moving, so the spacing or removing the rubber seals makes no difference.

There's conflicting evidence for and against which is very subjective, however independent testing shows that under certain driving conditions (stop and start traffic driving in particular) they can reduce intake temperatures (again very subjective dependent on vehicle in question, engine configuration and air density/pressueres etc...a lot of these tests are South California based) but they certainly reduce the effectiveness of the radiator, which can cause overheating issues within the engine bay

 

(cut and paste)

 

this means that if your rad is super effective you can possibly trade off some of that for cooler intake temps but if you already overheat (due in part to a poorly functioning radiator) then this will make the problem worse.

it's a high pressure area when the car is moving, so the spacing or removing the rubber seals makes no difference.

 

 

 

So the base of the windscreen is a high pressure area (when travelling at speed), in contrast to under the bonnet which is low pressure area, therefore it'll blow air in not suck it out...would that be correct?

I've had vents in my Z for over 7 Years now and that was running a stock rad up until last year when the rad finally developed a leak due to the age of the thing... Got a nice Koyo one now, just cause it came at the right price but a stock rad with vents kept the engine temps well down... Could do a 30 Min run down to DannZX place, running at full boost 1.2 bar in places and on arrival at his, lift the bonnet and the plenum would feel cold... Plenty of air being circulated around and vents are a great idea when stuck in traffic to release the heat!!

The base of windscreen turns into a vortex the air does not actually go.anywhere. if you let air out of engine bay with vents it will not circulate around the engine fully. In stop start traffic vents help, in actual driving shrouds help more,

I always wondered if having bonne vents caused any problem with letting rain water or car wash water in?

rear facing louvres as oposed to vents would cause a low pressure area to form in the slip of the air rushing over the bonnet, thereby allowing the low pressure air stalled under the bonnet to be littteraly pulled out of the louvres by the passing higher pressure air flow causing a mini vortex behond each louvre

 

this is why louvres were used in many sports cars of the past and military aircraft ........vents do not act in the same way unless specifically designed to do so .....such as the escort cosworth and lancia delta integrale

rear facing louvres as oposed to vents would cause a low pressure area to form in the slip of the air rushing over the bonnet, thereby allowing the low pressure air stalled under the bonnet to be littteraly pulled out of the louvres by the passing higher pressure air flow causing a mini vortex behond each louvre

 

this is why louvres were used in many sports cars of the past and military aircraft ........vents do not act in the same way unless specifically designed to do so .....such as the escort cosworth and lancia delta integrale

 

They are still used in many racing cars now, and some road cars, a few that spring to mind are Aston martins, pug 206, Evo 10.

 

As for raising the bonnet, there seems to be conflicting views and evidence online depending engine lay out, some people say it makes it worse, others say it improves it.

 

I suppose its down to if you notice a major increase, lower the bonnet. if not and you end up with a cooler engine, leave it raised

I always wondered if having bonne vents caused any problem with letting rain water or car wash water in?

 

Water should not be a problem if you place the vents beside the engine and also not directly above the turbo/manifolds.

I do not have an overheating problem when driving normally. But if I was to take the car to the track I think some vents would help a lot. Better to be on the safe side. Just with normal driving it gets so hot in the engine bay that it's not possible to touch anything before it cools down a bit.

Found some vents on ebay that I think could be ok on the 300: http://www.ebay.com/itm/08-09-10-11-BMW-E90-E92-E93-M3-GTS-MATTE-BLACK-HOOD-SURROUND-VENTS-/360459585258?pt=Motors_Car_Truck_Parts_Accessories&hash=item53ed10c6ea&vxp=mtr#ht_2077wt_1270

Hi trond, where in Norway are you?

I do not have an overheating problem when driving normally. But if I was to take the car to the track I think some vents would help a lot. Better to be on the safe side. Just with normal driving it gets so hot in the engine bay that it's not possible to touch anything before it cools down a bit.

Found some vents on ebay that I think could be ok on the 300: http://www.ebay.com/itm/08-09-10-11-BMW-E90-E92-E93-M3-GTS-MATTE-BLACK-HOOD-SURROUND-VENTS-/360459585258?pt=Motors_Car_Truck_Parts_Accessories&hash=item53ed10c6ea&vxp=mtr#ht_2077wt_1270

 

You would probably benifit more from getting a vented bonnet, rather than cutting up your existing one. considering its only 4 bolts to change, you could then have one for the track and one for the road. or have your original as a spare.

You would probably benifit more from getting a vented bonnet, rather than cutting up your existing one. considering its only 4 bolts to change, you could then have one for the track and one for the road. or have your original as a spare.

 

A bit more than 4 bolts. Also have to paint the bonnet. That is lot more expensive then a pair of holes in the bonnet.

 

Joely p: I live south in Norway, nearby a town called Kristiansand.

i've not read this fully but, my bonnets spaced, and can i just add air does flow out of my bonnet and over the roof at speed,

 

had a water leak way back when and the steam came right up over the windscreen no vortexes or anything, and particularly when sitting in traffic noticed since it was done the average temp dropped a couple of degrees,

 

although im now running a huge rad and nismo thermostat which have dropped it even more... (id say get a bigger rad before cutting your car up. )

A bit more than 4 bolts. Also have to paint the bonnet. That is lot more expensive then a pair of holes in the bonnet.

 

Joely p: I live south in Norway, nearby a town called Kristiansand.

 

Most vented bonnets are carbon fibre so no need to paint it, just leave it as a carbon fibre bonnet.

zx-tt has a nice one for sale