Brentis

I'm thinking of getting an open hood like knightsport or mazdaspeed. I have a greddy smic and like the idea of helping airflow through that plus and more importantly I want the engine to cool down.

So can anyone tell me if they have observed any significant improvements???

Thanks!

Brentis

no thoughts??

ttb

my guess would be that it's more help for when you shut down, or maybe in traffic, but if you're driving freeway speeds it's not going to make a difference.

RX7Elmo

it really depends on the hood. I've heard from people wiht the scoot hood that it makes a noticeable difference. Some even have probems where they can't get their cars to get out of warm-up mode etc.

ttb

wow

vudoodoodoo

So just warm up the car with the stock hood on then switch it when it's warmed up.

cpa7man

iTrader: (2)

I agree with the the theory that when the car is moving, not much benefit. Are you looking more an for engine temp decrease or engine bay temp decrease?

fdslave_g

I heard that the vent hood helps. But I still wonder myself if it's true and how much could it helps

Brentis

Well - if everyone agrees that the engine and the engine bay temps would be improved without a hood then one should be able to say that temps would also improve if a certain percent of the hood was vented.

I'm just wondering if anyone has any direct experience...

thanks!

TheCrazyAZN

iTrader: (2)

I have no real numerical way of showing you how it might help, but i do know, that when you get to a stop light or moving very slowly in texas summers, i can SEE the heat waves billowing out of the hood. Thats enough proof for me. But wouldnt a vented hood improve engine and engine bay temps even better when the car is moving? There is a lot of ambient space inside the bay all the times, and when the car is movin, there it will stay unless it has some sort of negative pressure to flow the air out, creating more cooling... Does that make any sense? Haha anyways, Brentis if you need one, hit me up!

Huy

Brentis

Huy - you are my guy for a knightsports replica... Preferably I want one whic has a good latch structure where I don't need hood pins.

I agree, vacuum increases in the front/middle of the hood as speed increases. This is caused from the redirection of air as it hits the nose, as speed increases the vacuum does as well. Further it gives an escape path for the trapped air in the engine. when released it also allows improved flow through the radiator and IC.

gotorx7

Mine definitely helps on the track - about 10 degrees cooler under hot conditions.

Can't see any difference on the street, but I run cool there anyway, and nearly always have the fans on.

FormerPorscheGuy

It should help keep over all temperatures down but it won't help you if your car is over heating. Upgrade your Radiator and oil cooling system first. I saw a huge decrease in temperatures when i did that.

DavidDeco

I noticed a big change. I have a Scoot Hood.

I posted this awhile back but to recap basically I was running right after my rebuild Water Temps 100+ and Oil temps 115 or so (it was a hot Florida summer but still..). That was with the new Fluidyne radiator

If I remember right, it progressed like this as I modded:

Datalogit used to turn fans temps on at full at 85 degress and replaced an apparently faulty relay, added Water Wetter. Water Temps stayed under 100 typically 95, Oil Temps about 110.

CWC Dual oil coolers (my single cooler was so badly stoned the fins were pathetic) . Oil Temps dropped to I think about 85.

A month or so later I changed to the MB Feed Version 1 style bumper, put on oil cooler ducts, and put on the Scoot hood when I had the car repainted. That's where I am now:

Oil Temps 60-80, and Water Temps rarely if ever budge over 86-87 typically 85 or lower.

I even posted a message back then if it was dangerous to have too low oil temps....that's a net drop of 40+ C degrees in 6 months even considering it's no longer summer.

Also, I have an autometer F H20 Gauge and then the PowerFC in Celsisu. They confirm each other. I also have a Delfi Oil Temperature gauge which is how I'm getting those.

David

DavidDeco

Just to add to my previous message, obviously the bigger front with the ducting probably had more affect on the oil temps than my hood.

I would definitley recommend oil cooler and radiator upgrades first but I think you'd see a noticeable if less radical improvement with the hood on top of it.

Razerx

The same effect of ram air or corbra jet (early mustages) prove this out. Now you want the scoop further back fromthe radiator as it will draw air in from the scoop and 'entrain' air coming out of the radiator and it will drop out around the transmission and udner the car. THe other effect is it will draw more in for a 'cold air' intake as well.

T88NosRx7

iTrader: (1)

I say do it, any little amount of cooling air helps.

MakoDHardie

The stock hood is really good for keeping the engine insulated during warm-up. Vented hoods are great for if you live in a warm climate or if its a summer switch out thing. Assuming you keep your car garaged if you live somewhere cold enough to have warm-up problems with the vented hood, one of the easiest solutions is to drape a towell or two over the vents while its warming up. Heat rises....this will slow it down and help to recirculate it within the bay while the beast wakes up. If your hood does not have insulation lining and no perimeter seal, then it will also decrease the insulation ability and increase the cooling ability of the hood. As far as the cooling effect vented hoods have on cars.... it does make a big difference, especially if you have upgraded your radiator and/or intercooler.

rpm_pwr

The best cooling mod you can do is put a 99 front bar on the car. Mazda had an SAE paper saying that they saw >100% improvement in cooling efficiency in the rad and closer to 150% imporvement for the oil coolers.

The same cannot be said for vented hoods since nobody has done the research. But since the stock rad is so choked of airflow (particularly on the series 6 and 7)that it would have to have a decent effect. Not to mention the reduction of heatsoak and the benefit that would have for the lifetime of the hoses etc in there.

PWR calculated that their 72mm core radiator had a whopping 5% improvement over their 42mm core on an FD. Having a front mount only magnifies the problem by throttling airflow even more.

-pete

1FooknTiteFD

GotoRX7, what type of hood do you have?

A lot of times when you change to an aftermarket front end with a bigger opening, a vented hood will help aerodynamics as well. with a bigger frotn end, the front of the car actually lifts up a little because of all the air going into the front. After I switched to a FEED Type 2, I can actually see the hood pushing up if I go for speeds over 80mph! With a vented hood, the excess air in the engine bay will be able to exit better and get out and that's enough reason to do it right there

cpa7man

iTrader: (2)

Hey Pete, Where can I get more info on this 99 front bar.

san diego fd3s

I think he means the 99 spec bumper.

Brentis

Thanks guys. I appreciate the input.

I do indeed like the 99 spec front, but from a cost perspective the hood seems to provide more bang for the buck.

Does anyone have any cost effective ways to add another oil cooler? From what I've seen they are pretty proud of the aftermarkets.

Cihuuy

if you want to do a rice mod... u can put a couple of washer to the bolt of the hood... this will lift up the end of the hood near the wipers... and leav a small gap to let hot air out...

dont know how much temperature drop you will get but its so rice that it is cool... hehehe

Fritz Flynn

iTrader: (263)

I had a knightsport hood on my car and it made no difference when I took it off plus it was a bit heavier than the stock aluminum hood . Better ducting and a mazda speed front bumper will make a dramatic difference. My car is currenctly having a larger oil cooler and some duct work installed because of heat issues with my front mount ic. Mitch Piper said the only good alternative was a better bumper but I just don't care to spend excess of 1k on one. He is going to install a bigger single oil cooler, cut a larger hole, and fabricate a better duct. He is also cutting the center section/mouth opening larger and reducting that for the radiator. I am hoping these two changes will keep my temps at or below 92c during lapping events. If it does not work I will try two large oil coolers and a mazda speed bumper and if that doesn't work I'll just give up on the front mount