airflow in the NB
 

driving to north carolina with the AC on in hot weather .... the faster I go, the hotter she gets. cruising at 55-65 the temps are right around 210F. every 10 mph over means 10degF higher coolant temp.

Ambient was 87F...

note I haven't done anything about cold air intake or MUCH with airflow... I've got work to do there but I'm curious why faster = hotter.

I mean aside from the engine making more power to go faster... it's not like I was in boost or even approaching it. it was like... 15 inHg vac.

that is strange..... Everything I know would tell me that the faster you go the better the airflow.... Do you have a lower engine sheild on???

Same thing was happening tomy NA last summer with no turbo. Adding back in the undertray and front shroud thing helped a lot, as did removing the stupid grill that the previous owner had put on. I mentioned this to a colleague of mine in wind engineering, and he said that, in relation to wind on buildings, a screen acts more and more like a solid wall at faster wind speeds. So, in regards to a radiator, the same would hold true. The higher the speed, the more critical it is that air has no other way to go, other than through the radiator.

I have the same problem. I also have sky high IAT's, because my filter is right above the radiator fan, like a old school fm kit..

I put the under tray back on, and that helped some, put a much lighter mix of anti-freeze in.. with water wetter, and a 160* t-stat.. we'll see how that does..

I still have no A/C, relay will be here this week so i can make that go.

Hi cruising EGT?

this is why FMIC's are evil :bigtu:

blah blah blah.

12-1300 F max. runs well.

It's probably the gaps around the IC at high speed passing all the air. I tried to foam it in so air couldn't go around but I checked later and the foam was missing... air wanted by bad.

I have a makeshift undertray but it doesn't enclose the sides like the stock one. That's probably an issue too.

Ducting it is.

yay for fun projects....

Have you made any progress on this, y8s?

My f'in temp gauge started creeping up up up today.. running the heat got it back down to normal, but it's annoying for sure.

Edit: damn, you even have the Koyo.. I'm still stock.

I've sorta made progress...

I ordered a 90° 4" tube and connector to mount the filter more behind the headlight.

I picked up some 3" shiny silver dryer hose. Gonna try to route this to a high pressure spot in a fender or something to get fresh air to the hole behind the headlight.

I picked up some rolls of PSA backed insulating foam weatherstripping. This will be sealing holes around the IC/AC/radiator.

I have not done anything with any of that... and I need to get some better sheet materials to make shrouds with. The stuff I got is flimsy and comes in roll form--oops. Next round will be thicker to get some rigidity. I may also form up a sweet filter box.

IDEALLY I will have a bunch of dividers/diverters that point the air only through some cooling device and not around any of them.

I need to get some real thin gauge stainless or aluminum and cut some shields.. I have a CNC cutting table, but no sheet metal brake (break?) to bend the stuff.. I could make some kick ass air diversion panels with a brake.

I have a vise brake... :)

http://www.amazon.com/Grizzly-H3243-.../dp/B0000DD4UU

But if you use thin AL and it's pretty big, just bend it over the side of your work bench...

that's pretty neat.

We actually refer to our vise as the Amish Brake. We actually renamed the fabrication area from "Amish" to Mennonite, because we remembered that we have electric. :)

This stuff is made for fab'ing shrouds/spoilers etc.
I've used it on numerous race cars, and on my street Miata.

ooh sweeet. what's it come like? roll or flat? does it curl up when flat?

it'll have a curl to it (manufactured as a roll) - but lay it out in the sun and it'll flatten right out

that sounds pretty close to what I have actually.

by the way... 5.15 a foot or <$50 for 25 feet? wtf.

found my front lip splitter material....

http://www.bsrproducts.com/product_i...roducts_id=518

I bought a Koyo today.. be here next week.

New engine, new radiator, etc.. Same problem.

I need to figure out some ducting or diversion panels, etc.

well what in the hell could be going on with your car.

i dunno. i even had my turbine and manifold ceramic coated.. ;)

Where's the pics of your car man?
You like the Koyo besides the fact that they're expensive and it didn't help your cooling issue any?

you ever checked your thermostat? what mix of water do you run? have you verified fan working?

i could care less, honestly. the rest of my under hood area is so hideous that the dressup is pretty trivial.


y8s, when i put the new engine in, i didn't change the t-stat, so it has a 5k mile OEM t-stat, which should be 192*. I still have a 180* that has approximately 500 miles on it that I could swap in.

Coolant is mostly 50/50 pre-mix, a bottle of waterwetter, and then some distilled water to make up the rest. It's probably like 40/60 at best.. the mix that was in there when the shit overheated was probably 15/85, it was mostly water.

I guess when I get back from vacation, I am going to check the radiator cap and pressure test the cooling system. This shit is going to get old real fast.

Aero drag requires power to increae with speed^3.
Cooling capacity through the radiator may go up with speed, maybe speed^2.
So cooling capacity can't keep up with heat production as you increase cruise speeds.

Bet the high pressure under the front end isn't do too much for your rad flow either with that make shift under tray. I ran a Miata on track w/o that undertray and at 100mph it looks like the hood is ballooning. :eek:

my plan is to build some diversion panels to force air through the radiator. I have a cutting machine at my disposal, so I just need to get some thin gauge steel (i'm thinking 20 gauge)..

I was planning on using cardboard to make templates, transfer that to the steel plate, then use that to transfer to the software.


What I don't understand is that I didn't have this problem at all last year, and I had no under tray on there at all.

When I first installed my turbo 6 years ago I was in a hurry to drive the car and never installed the black nose piece or the underpanel. Car had A/C then. Drove down the interstate in the Carolina summer and couldn't use the A/C above 70mph cause the temp needle started moving. Didn't have a way to measure actual temp but knew the gauge didn't start to move until it was getting hot. Then shortly after that I barely made it to Deals Gap for the July run due to high temps going up the mountains. I installed the undershield and nose piece and highway cruising was solved. Then A/c got a leak and I wanted to track it at Roebling Road in the summer, so I removed the A/C condenser(?) from the mouth and put in ghetto shrouding using the pool noodle things. took it to the track and had no problem with overheating.

people who say their car doesn't overheat after several boosted runs on the street haven't really tested the cooling capacity. On the track for 20 to 25 minutes is a totaly differant ballgame.

Ben I wish I could have helped you with some IAT #'s while in boost but I had to reboot my laptop and lost a boatload of datalogs and now i have like 5
Just got my car on the road this week. running it without a hood right now and using Corky's small 6.5 inch intercooler. one 1st to top of 4th gear pull at only 8 psi shows IAT going from 34 to 40 and quickly back to 36 then 34.

Anyway Getting air in the mouth and through the radiator/intercooler and out the engine bay is the way to go I'm convinced. Richard Murray has done alot of testing with coolant reroutes and he believes strongly that reroutes do little if anything to prevent overheating but rather are beneficial for a more even cooling of the motor when compared from front to back.