bonnet jacking

Has anyone doen this or know any more about it?

I plan to jack up my bonnet by using some washers under the hinge bolts. The idea is that the bonnet will then let all the hot air escape with me cutting a big vent into it. When the winter comes I can then put the bonnet back to normal, which you cant do with a phat vent.

Comments? Good/bad idea?

I don't really understand why. Is the ventilation not adequate as is?

Most manufacturers have spent a lot of time with development of the under bonnet temperature, ventilation and heat radiation. So if the car is original, don't do anything unless you know what you're doing.

Sounds like a cheap way to cool down your engine, except it would look kinda funny with the hood/bonnet sticking up. I would just get a carbon-fiber hood. Better heat dispersion than metal and much much lighter.

heh, when I saw this thread, i thought the topic meant "bonnet stealing"

Uh, afraid your car is going to be snowed-in in the winter?

(Pardon the pun..):bloated:

Car is not stock. I have (amongst other thngs) a custom cold air intake (simlar to iceman) and soon will be adding 4-2-1 manifold. I have seen cars that have a slight gap (5 - 15mm) to let out cold air which doesn't look too bad as you can hardly notice until you really look closely.

At the moment the engine is getting real hot and affecting the cold air system, i dont really want a vent as most look stuck on or silly.

Wow, your very brave hotting up a Micra, there not exactly the performance car of the century. But then living in the UK, I guess you have to take what the insurance companys will let you.

On an older car, like a MK1 Escort what prescribe could possibly have some benifical affect, however a lot has changed in the years between an old Esci' and your Micra, and Nissan will have put a lot of thought into how air flows around the engine bay of your Micra.
Chances the car is designed in such away that air flow if out the bottom of the car, and not out the top of the engine bay.
There is a chance that messing with it could actualy have a bad effect on the car, causeing incorrect airflow through the radiator, or negativly effecting aerodynamics. It could even draw air away from your intake.

Removing excess heat from your engine bay is something you simply dont need to do, your car is not modfied enough to be producing any more than stock. The best way to get cold air to the intake is with a cold air intake, or CAI.
This ducts air from out side the car much like the stock intake would have, but uses a more efficant design.
If you can not find an aftermarket one for your car, then you can easily make your own. Use your existing intake, and simply add enough extra pipeing to it, to get it to the frount of the grill, or corner of a wheel well or, even the orginal intake point, and use a pod filter on the end of it.
Use carbon fiber or similar piping in the engine bay, to minimise heat soak, and damage from the engine temp, and then you can use cheaper PVC drain pipe away from the engine.
Any actualy performance gain is likely to be minimal, as with all after market intakes for modern cars, but the car should sound better.

Wow, your very brave hotting up a Micra, there not exactly the performance car of the century. But then living in the UK, I guess you have to take what the insurance companys will let you.


No offence but a Civic is hardly a fire breathing dragster. Not sure where you live but in the UK they are not.


Removing excess heat from your engine bay is something you simply dont need to do, your car is not modfied enough to be producing any more than stock. The best way to get cold air to the intake is with a cold air intake, or CAI.
This ducts air from out side the car much like the stock intake would have, but uses a more efficant design.
If you can not find an aftermarket one for your car, then you can easily make your own. Use your existing intake, and simply add enough extra pipeing to it, to get it to the frount of the grill, or corner of a wheel well or, even the orginal intake point, and use a pod filter on the end of it.
Use carbon fiber or similar piping in the engine bay, to minimise heat soak, and damage from the engine temp, and then you can use cheaper PVC drain pipe away from the engine.
Any actualy performance gain is likely to be minimal, as with all after market intakes for modern cars, but the car should sound better.

I do have a custom CAI sitting in my front grill, it has been built to 130% of engien capacity giving me gains in the mid range, a longer pipe fitting lower to the ground would give colder air but put the gains higher up in the power band.

I want to add a performance 4-2-1 manfold, which unlike the stock system is not heat sheilded. I know that others have been very pleased with bonnet vents but the problem with bonnet vents are that they look dumb.

Then coat the damn header with ceramic. That, or wrap it with those braided heat sleevings.

Originally posted by dilated

I want to add a performance 4-2-1 manfold, which unlike the stock system is not heat sheilded. I know that others have been very pleased with bonnet vents but the problem with bonnet vents are that they look dumb.


Ok, 1st of all adding a set of unshielded headers will have little to no effect on the under bonnet engine temps. You may see a rise of a few degree's, but certianly nothing that will have any effect on the cars performance.
However if it does still bother you then as 454Casull a ceramic coat or properly applied heat wrap will keep temps down.


and 2nd, Yes, about 90% of all Civics made are slow little econo boxs, and many would have a hard time keeping up with your micra, but there are a small number of Civic's that will run rings around virturaly every single FWD nissan ever made, namely the SiR and Type R models sold in Japan, and the VT(iR) and now Type R models sold in the UK Europe, and Australia/New Zealand.

Thanks for your advice. Sorry about the civic dig - just a little joke, everyone seems to hate little japanese hatches. I actually like the civic especially the Generation 4 and 5, i think honda lost it a bit after that.

Sorry to doubt all the advice you have given but I really dont beleive that nissan have got everything right with the car, many micra owners have reported good things about bonnet vents and I hve seen a lot of japanese march's with jacked bonnets so I thought these bioys might know what they are doing.

I knwo what your saying about my engien no being that hot, but the CAI does get very hot after about 40 mins. I have done a throttle body coolant bypass which helps but I really would like to do all I can before spending (or wasting) any money.

Also have heard that wrapping the header can cause exsessive heat build up which could crack the mainfold or exhaust system.

Thanks for your advice. Sorry about the civic dig - just a little joke, everyone seems to hate little japanese hatches. I actually like the civic especially the Generation 4 and 5, i think honda lost it a bit after that.

Sorry to doubt all the advice you have given but I really dont beleive that nissan have got everything right with the car, many micra owners have reported good things about bonnet vents and I hve seen a lot of japanese march's with jacked bonnets so I thought these bioys might know what they are doing.

I knwo what your saying about my engien no being that hot, but the CAI does get very hot after about 40 mins. I have done a throttle body coolant bypass which helps but I really would like to do all I can before spending (or wasting) any money.

Also have heard that wrapping the header can cause exsessive heat build up which could crack the mainfold or exhaust system.

Also have heard that wrapping the header can cause exsessive heat build up which could crack the mainfold or exhaust system.
Melting or cracking?

Sounds like it would hirt your aerodynamics, but if you're willing, go for it. Myself, i wouldn't bother doing it to a Micra, but if that's your thing, all the power to ya.

Wrapping the original header in ceramic is perfectly fine, as long as it is stainless steel. Its those aftermarket ceramic headers (sometimes oem) that crack. You see, the parts companies think they can get away with using non-stainless steel underneath their ceramic headers. The weaker metal might eventually warp and crack the ceramic.

As long as you stick to stainless steel (or stronger) you'll be fine, even if it starts to get discolored.