Explain what that is? Are you talking about raising the rear of the hood and hoping that it extracts heat?

 

See my post #30. Basically a sheet metal lip to kick air up as it passes over the hood at the opening behind the radiator. My understanding is that makes the pressure differential greater and extracts more heat.

 

Anybody?

How does a 20 degree drop in ambient temps relate to coolant temps? Thanks.

 

Depends on the placement of the range of 20 degrees compared to the target temp of the thermostat.

155 -> 135 with a 190 degree t-stat is probably drastically different than 80 -> 60 with a 160 degree t-stat.

 

i don't think that is what he meant. i think he is asking if he had coolant temps of 220 on a 95-degree day and hits the track on a 75-degree day can he expect to run significantly cooler.

I'd assume so, ambient temps have a big impact. I once ran my Boss 302 on a 110 ambient temp summer day at the track and it went into limp mode due to overheating. the same car, on the same track with 95 ambient temps was fine to beat on all day turning similar lap times.

 

Exactly the answer I'm looking for, want to get peoples opinions and experiences with this. Preferably some of the SoCal guys can chime in with how difficult Autoclub Speedway is on the cooling system versus other local tracks that I have been to (Willow Springs, BRP, etc).

 

So I went back and looked at post 30 and read what you have written. I am still confused on what exactly you are trying to do. Are you saying you are going to duct off from the bottom of the radiator all the way up to the vent and then all around? If so then I think that would well. If that is not what you are planning on doing, then I need a simpler explanation for my 5 year old brain.

 

Whatever you do, do not duct the front of the radiator and add an extractor in front of the hood-hump. Everyone is lying about the effectiveness. Only you have absolute truth.

 

Ducting is only in front of the radiator from the mouth of the bumper to the radiator itself. The opening in the hood behind the radiator but in front of the valve cover is to lower engine compartment pressures because the location of the opening is a low pressure zone and the engine compartment is a high pressure zone. The lip in front of the opening that I want to add should decrease the pressure further and make the delta in pressure from the engine bay to over the hood greater at that location, hopefully pulling more air through the hole in the hood.

End goal is to increase the delta in pressure from in front to behind the radiator. Higher the delta, more air passes through and more cooling is done. To a certain extent.

Run-on sentences over.

 

Got lucky! Found a used TSE radiator that I could get the money together for. In the mail already and should be getting installed on the car next weekend. Stoked!

 

Do you have a fan shroud around the radiator? In order for an electric fan to cool properly you must run a fan shroud

 

I am using the OEM cooling fan and shroud combination and will be using the same fan setup on the TSE radiator as long as everything fits. I aim to not have the fan be a big portion of my cooling at speed, only really need it to cool down when coming off of track and to work while driving to/from the rack track.

 

I believe conventional wisdom is that on track cars you do no want a fan shroud behind the radiator. I believe that they end up blocking more air then they let through. Honestly with the TSE radiator, proper ducting before it, and the undertray, you should not be having over heating issues.

 

That's what I'm hoping for! Only one way to find out.

 

Got the lip/riser added to the hood this weekend. Came out a little taller than I originally thought but it should do the job well. Man my car is looking more hoopty every day...

 

Thanks for posting those pics Hustler. Your ducting looks almost identical to mine, except for the oil cooler hole and the fact that yours is made out of plastic instead of Aluminum.

Were did you get the plastic?

 

Fans are for street cars, A/C function, and idling in the pits. They will not help when you are on track.

Theseus doesn't run a fan shroud, and neither does Rover. I don't understand why people continue to buy them.

 

+1

When we tested shrouds several years ago we found they only improved pressure differential and engine temps a little when stationary. As soon as the was over about 20mph, they blocked flow even with fans on. Almost no OEMs use full coverage shrouds and you will never see one on a top level race car.

 

Quick question on the subject of fans, when having some overheating issues, do you guys find that running the fan is better than having it off at speed? Or does the movement of the fan have a negative/negligible effect?

When I was overheating last time out, I lowered the temp at which the fan comes on to just have it running all the time basically. Thought it might be better to have the blades moving some air rather than just blocking airflow.

 

If the airflow across your core is bad enough, the fan will help a little. It's a band aid and warning sign though. If a fan lowers clt temps at speed, you have an airflow problem. Case in point, most bone stock Miatas with A/C will run hotter at 80mph steady state than accelerating hard at autocross speeds. The reason is the airflow leaks around the rad progressively raise the air pressure in the engine bay with speed until it just about equals that in front. Lots of leaks and poor exhaust from engine bay. Address those things and fans are superfluous once moving.