will scoopless gt4 overheat?

[flygt4]

if one were to replace a st185 bonnet with a zr/gtr bonnet for short periods of time wuld it over heat?has anyone tried this before?assuming the i/c has been frontmounted of course.are the vents actually that functional that they r neccessary.

[Twolitre]

Nahh it'll be sweet man, ST165's and most other turbo cars such as Silvias, VR4's Supras etc don't have vented bonnets and they don't overheat, are you going to remove your aircon when going front mount?
The vents are mainly there to give the air somewhere to go once it has gone through the scoop and through the IC

[flygt4]

yeah i was juss a lil concerned seeing as gt4's run very hot anyway and knew there was issues with st165's melting/damaging stuff underbonnet hence the addition of vents in the st185.i find my temp gauge will stay under 1/4 if moving tho so it culdnt be that bad.yeah my aircon will be gettin chucked,it doesnt work properly anyway. it will be worth it to have no heatsoak.was thinking it mite be fun to throw on a non-scooped bonnet,zr badge and my lil 14's every now and then for a laugh. wuld be nice to hav the option to hav a lowkey car too wen i feel like it.

[Twolitre]

You could probably get away with running an ST182 bonnet all the time as long as you got a few things under the bonnet heat wrapped and hpc coated. Some people even use spacers and longer bolts at the back of their bonnets to allow airflow to exit the back of the engine bay, however I'm not sure if this is illegal or not and considering you're ditching the aircon you shouldn't have any issues with sufficient airflow through your radiator.
A debagded ST185 with ST182 bonnet and front mount would make a mean sleeper

[flygt4]

thats the plan man.only on occasions tho.plus wuld be a good way to not attract attention.heading the opposite direction than doing the car up , sorta do it down a bit.change the wheels and bonnet and off id go , in my lil 2L front wheel drive silllycar or so it wuld seem.

[Malcolm]

you need to be careful if you decide to raise the back of the bonnet with washers/longer bolts, as there is a hook on either side of the bonnet, just near the hinge, which is designed to stop the bonnet from going through the windscreen should the bolts sheer off in a crash, and if you raise the bonnet too far the hooks will no longer catch it. Somewhat important because you could potentially be decapitated in a head on crash if you are particularly unlucky.

[Scottie]

there is a rubber strip between the top of the firewall and the bonnet. If this is removed it should aid in vented hot air...just an idea

[Jools]

The vents on the side of the 185 bonnet arent for heat reduction, theyre to help prevent the engine bay from pressurising from the scoop and blowing the bonnet off at high speed

I ran my 182 bonnet even with a top mount on (yes i knew it was a dumb idea, but i didnt have a 185 bonnet then) and it was good for 30~40mins before it got so hot the ECU cut the boost down. But even then the engine temp was only just over half way.

But i gotta say one thing...STOP STEALING MY IDEA!!! Ive just front mounted and am goin back to the 182 bonnet

[flygt4]

thanks for the input guys.hahaha jools dont worry we in different cities , and the more celicas goin hard the better.if i ever see another st182 pulling suspiciously hard ill know who it is then.it all depends on me getting off my ass and sorting my frontmount anyway.

[Malcolm]

Jools, I don't know where you heard that bollocks about the vents being there to stop the engine bay from pressurising and the bonnet blowing off at speed, but it is simply not true. Apparently there were some problems with the st185 bonnet buckling at high speeds in early testing for rallies, but these bonnets were much lighter versions, with significantly less structural strength to them. If those 2 little vents really did stop the bonnet from blowing off, then gtz's, gt starlets and the like would be in serious trouble because they have a very similar scoop design, but no extra vents.

Anyway, flygt4, if you're wanting a front mount, there's a good chance I will be selling mine (piping + vr4 intercooler) in a month or two. Let me know if you may be interested, because I will probably be upgrading all my piping when I install the Blitz turbo + intercooler.

[celica_tommo]

yeah... thats true. air can always escape underneath the car... but I would say the vents would help air circulation around the intercooler and at the top of the engine bay

[deaf_rattle]

dont the vents come closed off anyway?
I remember there being insulation under them standard.

[flygt4]

no there is holes in the insulation under the vents , which doesnt matter really coz i ripped it out.
All_Fours -- i would be very interested in that aye specially if u got the piping coz thats the bad bit.hav u kept ur compressor housing the same way?i heard of people roatating it to make it easier to pipe in.i was gonna go for a vr4/evo cooler anyway.let me know when ur ready to sell it

[Distrb]

you need to be careful if you decide to raise the back of the bonnet with washers/longer bolts, as there is a hook on either side of the bonnet, just near the hinge, which is designed to stop the bonnet from going through the windscreen should the bolts sheer off in a crash, and if you raise the bonnet too far the hooks will no longer catch it. Somewhat important because you could potentially be decapitated in a head on crash if you are particularly unlucky.

Every car I've ever seen that has been in a frontal usually has a bonnet resembling crushed tin foil. The bolts holding the bonnet to the hinges are almost always intact, unless the hinges themselves have been destroyed, which usually results in a taco-shaped bonnet.

Bonnets are not load bearing members. They are relatively flimsy panels designed to crumple on impact.

To decapitate anyone in the front seat, the bonnet would need to absorb all of the impact forces without folding/crumpling. I have never seen a car that has been in a frontal with an intact bonnet that has been rammed back through the windscreen.

just pointing out the flaws in the head slicing bonnet urban myth

[Jools]

Just got my car back from having the fmic installed, and its just as frickin hot under bonnet as its ever been (prob a bit more so since all the heat shields have been pulled off), so im a bit weary now about goin for the unvented bonnet.

As for that bollocks bonnet decapitation thing All_Fours came up with, Distrb is right, the celica bonnet is designed to buckle in the middle, if you look underneath along the sides of it, you can see two arches in the support beam.

[Shotgun]

Spacing up the hinge itself is probably a better option anyway if you were worried about hook situation. May not work for big spacing though.

[Malcolm]

Ok, I didn't say that if you space the bonnet you will be decapitated in a head on, what I said was that if the bolts sheered off and the hooks didn't catch the bonnet it could go through the windscreen, and potentially decapitate you (ok that may be a bit over the top, but it could still injure you). The bonnet crumples because it is secured at the back, if the bolts sheer off on impact, either due to age, over torqing, being previously damaged, or being replaced with poor quality/low grade bolts, and the hooks are no longer able to catch the bonnet because it has been spaced, then it could definately enter the cabin, especially if the impact shatters the windscreen, as an intact windscreen would tend to deflect the bonnet over the top.
Anyway, I made that post as a safety warning to someone being presented with a modification without knowing the full implications, and if you weigh up the odds and decide it's worth it for the small risk to the health of yourselves and the potential occupants of your car, then by all means, space away

flygt4 - I have mine with the compressor housing rotated, but when I sell I will include the modified wastegate actuator, which is the only part that needs alteration to rotate the housing. It is otherwise a very simple job. The piping is all 2" mild steel but is ceramic + powder coated to prevent rust (has a 10 year guarantee) and to reduce heat transfer from engine bay to pipes. Not sure on how modified your car is, but so far this setup seems to easily support over 300hp and low 13 sec 1/4 miles
I will let you know when it starts coming off (should be within a month, as I just want to race 1 more time before upgrading everything). I have some pictures too if you want to see.