ED_MX5

Cut around oem bracing, matched to width of rad for later ducting <br ><br >Hello all. Recently done these vents to my oem hood. Cut around the bonnet bracing for these. Had done a bit of reading and they seem in the right spot. Gonna do more testing to see what difference it makes.
Got a few questions,
1- what are some good ways to test if I'm evacuating air or sucking in?
2- what is the ideal angle for a gurny flap? I will be making a fibreglass one soon to run across all three at once.
3- any good ideas to make edges softer so I don't have police whinging about it due to sharp edges?

Cheers, Ed

HHammerly

iTrader: (3)

I have a similar setup, did a test using strings for flow viz and it is extracting air from the engine compartment very well, i have a 3/4" lip on the front of the openings

ED_MX5

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They look great. Much work to get the lip? Would like to try that with mine perhaps instead of one all the way across.

hornetball

iTrader: (4)

TDR recommends venting the sides of the undertray, which seems contrary to most other recommendations.

Overheat Solution!!! Maybe.

Anybody ever A/B test this? Are the undertray sides low pressure relative to the engine compartment? Certainly easier and less visible than venting the hood.

Leafy

iTrader: (1)

Even if it did work, I'd avoid it since you dont want any more pressure in the wheel wells than you already have.

aidandj

iTrader: (5)

Turning fans on earlier on the track wont do anything. Because fans dont do anything at speed. So i'm already ignoring what he says because of that.

jmann

I would not discount what Gary from TDR is saying as he is very knowledgeable about dealing with heat issues as he runs in 100*+ heat with the HUMIDITY the same. I have ran down in texas with him on several occasions back in 08 and 09 and if he says it works I for one would think it worth a try. He is a very accomplished driver and knows of what he speaks in the heat. Come to think about it running a splitter is doing the same thing. I have also seen cars with holes in the fender skirts to vent engine compartment heat out into the wheel wells as that is a low pressure area compared to the engine compartment.

timmcc02

So last night I read through this entire thread and found a lot of good information and ideas I had not previously thought about. I have a MSM and with summer upon us my stock cooling system is being taxed. It's lightly modded, intake, downpipe, intercooler, stock ecu. Where would be the starting place in seeking to keep coolant temps closer to the 200 mark? My thought was starting with replacing the old factory radiator as its a failure point eventually, but seems all the other MSM owners have the same issue even with an upgraded unit.

jmann

Read the link in post 464 from Gary at TDR and do what is suggested. Upgrading the rad. is a good idea but it doesn't do much good if you don't seal it, so that is probably the most important thing is to seal it so all the air has to go through it. If it is used mainly for DD duty seal the fan shrouds so it sucks more air in traffic and make the fans turn on sooner and as Gary msaid try cutting some relief holes in the side of the under tray as that should help increase air flow and evacuate hot air out of the engine compartment, Sealing the rad intake to the rad should be nbr ! though in my opinion.

RotrexMiata

What is the air flow under the engine? Under tray is recommended for proper cooling FI setups. Now maybe not? I was considering mounting the oil cooler horizontal under the engine with cutout in under tray..

jmann

You want to keep the tray, cutting the sides allows all the air coming into the engine compartment a relief area to decrease pressure in the engine compartment. which should increase air flow through the sealed rad.. Basically same as a splitter would be with no sides.

Mobius

iTrader: (2)

Personally I'd rather have a second, vented hood (which I do) that I absolutely know will evacuate air from the engine compartment and increase flow through the radiator rather than mutilating the undertray. The wheel wells are high pressure areas; I don't know and haven't seen instrumentation comparing that pressure to engine bay pressure, the possibility of flow reversion is real. We often mock OEM design considerations but the undertray was built as it was for a reason and one must assume some form of modelling or experimentation went into it. It does have diffuser exits out the backside.

Not trying to knock Gary at all, he's done a lot of good work for the miata community.

jmann

I doubt the pressure is higher in the wheel well area then the engine compartment with the air that is entering through the grille opening plus as the air exits it well flow to the rear. Also this is what is taking place with our home made under trays and splitters which are wide open on the sides. I agree that venting the hood is a good move but for some that DD their cars and don't want to cut on their hoods and don't want the southern rain storms pouring water in on the engine this should surely help. .

RotrexMiata

Wish Emilio and The Pass would comment.

emilio700

iTrader: (3)

I disagree with John's conclusions but that won't stop him from arguing the case. Good guy but he can be a bit hard headed

RotrexMiata

Thanks Emilio

jmann

I'm not arguing, just happen to have a different opinion, you must have been listening to Brian Kelly. So you are installing sides on your under trays. As I remember on crusher the under tray didn't. I have seen a lot of splitters and plywood under trays that don't, including mine.
Lets also not forget where Gary lives, South Texas where you walk out the door and you are instantly wet. He designed a really nice intercooler and turbo setup not to mention splitters and other merchandise and I'm sure he isn't giving out info to his customers that he hasn't put several miles on himself down there on track and street.. Relieving the air pressure from the engine compartment has to help cooling and this gives some air a path of least resistance over trying to go past the subframe, steering rack and oil pan area. The air is exiting down low and being swept rearward and as stated the wheel well is high pressure [ I have vents in my fenders] and the air coming out the sides well be less air pressure then the wheel well so well be swept rearward..
Everyone can do as they wish but I go back to the fact that Gary is not one to say something without having tested it for results in one of the most humid and hot areas
Like stated above I don't know for sure but it makes sense and I for one would listen to him

greddygalant

iTrader: (3)

Since this is a cooling thread riddle me this.
Msm block with forged rods/stock pistons. Coolant reroute with 180 degree t stat, koyo hyper v radiator/cap with ducting,fab9 stage 1 intercooler. Ducting running from front bumper opening past IC to radiator. Oil cooler mounted to the back of the radiator with 1 fan on the other side. Running water and water wetter. Hood is vented, new headgasket, water pump, etc. Car is running 18psi on an msm turbo with upgraded billet compressor wheel to a peak 311whp. In 1.5 laps at full till the car goes from 180 degrees to 235 and just kweps climbing. Last year I ran the same setup with worse ducting, bigger intercooler covering more of the radiator, tons of boost leaks but at 15 psi on a stock msm turbo making about 250wheel with no issues.
I thought the head gasket was blown so we replaced it, and did a full cooling system check as well as having the head checked out for cracks or damage. Car still has a heater core but I don't think that a clog there would cause it since the thermostat is open and it's bypassing the core. The radiator is only a year old and appears to have good flow with no blockage. I'm at a loss, curly and I have tried damn near everything. I'm considering bypassing the core and checking the radiator for Hotspot before pulling the motor and having the block checked out. Any ideas would be greatly appreciated.

emilio700

iTrader: (3)

More rad. I would suggest the big boy TSE. Vented hood?

aidandj

iTrader: (5)

Does it overheat the same if you run less boost? Try a 250hp tune and see if it overheats. If it doesn't overheat then the added power probably pushed you over your cooling capacity. If you get overheating at 250hp and you didn't last year then you have a new issue.