next thought! cooling. why is to so god dam big!!!

[azn2nr]

ok, good friend of mine, started his build same time as mine. but when we started our subie builds his honda civic si was finishing up and came off the dyno with 400+whp at 10k. the heat that comes off his turbo can be felt in the cabin yet his radatior is a stock replacement pwr that makes the car run just as cool as stock, the spoon thermostat actualy helps keep it even cooler even when beating on it on a hot summer day.

recently suberboy went v-mount (custom) on his swapped impreza using a radatior alot smaller than factory. and it keeps him cooler than the factory rad too. my old auto radatior has alot of unused space from the auto trans cooler built into it and i want to get creative with a few things since im already getting into some custom work and im wondering exactly what temps do i need to see to keep the motor safe and who here thinks i can use a smaller more efficent radatior safely to save some weight and space?



pic of his radatior for refference. my turbo is about teh same size but i wont be seeing revs like his

[Splinter]

I ran a stock N/A 4EAT rad in my TLeg, I dont know exactly how much power it was putting down, but Id hazard a guess in the 200-220hp range.

[azn2nr]

see though im looking at 400+

[Splinter]

The NA cooling system is significantly smaller than the turbo system.

With an all-aluminum aftermarket rad (like a Koyo) and a better thermostat, it should easily be able to support that.

I dont think it'd be necessary to take extreme measures (i.e. silicon coolant lines, higher flow rad fans, extra rads)

[azn2nr]

i dont want to use a huge koyo. its heavy, holds more fluid, which is heavy, and i belive is unnessary. anyone care to prove me wrong?

[ramathorn]

thread revival because im in the same situation (wanting to free up some space and drop some weight up front). right now ive got a new 14" slim fan from an old car i was thinking about putting on as soon as i decide on a radiator (i need to replace mine for other reasons not just because im looking for an upgrade).

does anyone know what the stock 2 fans put out as far as cfm?

[evolutionmovement]

There must be some formula for figuring BTUs/HP with specs for radiator area x number of rows and alloy vs. brass. I'd like to know this myself as I want to fit a small single radiator in a NACA cowl that can cool an F20C that will be almost completely enveloped in bodywork (no airflow over the engine, just some extraction venting).

[Splinter]

Well you're rarely putting out max HP, so theoretically you could actually run a much smaller rad than what your peak HP would suggest

[evolutionmovement]

Good point. In my case a 1000 lb. vehicle would run out of room before it could use around peak power for more than a few seconds.

Taking that into account, you could figure approximately what you would be making for power at a high cruise speed in high ambient temp and add a little capacity for insurance. Unless you're leading a high speed chase it's unlikely you'd need peak HP capacity for longer than it takes to run a 1/4 mile.

[Splinter]

As a rough guide, on most otto cycle engines have an efficiency of about 20%. This means an engine that puts 400hp to the flywheel is actually generating 2000hp of energy. 1/3rd of this is lost to the cooling system (666hp)

666hp is about 500kW of energy

500kW = 500kJ/s = 631btu/s

Thats as far as I can get you... and take all those numbers with a salt truck.

[ramathorn]

damn to me that makes zero sense. maybe i shouldve finished college.

[SemperGuard]

A 3 month old Stock NA Legacy radiator will not cool a stock turbo engine at the track, an actual race track, not a drag strip. Daily driving is fine, and dicking around on city streets its fine too, but it wont work at the track. Period. At least not when ambient is 110+ degrees farenheit. Ambient would have to be way less

[evolutionmovement]

Good to know as I may have to get the beast running again with an N/A radiator.

[Splinter]

A 3 month old Stock NA Legacy radiator will not cool a stock turbo engine at the track, an actual race track, not a drag strip. Daily driving is fine, and dicking around on city streets its fine too, but it wont work at the track. Period. At least not when ambient is 110+ degrees farenheit. Ambient would have to be way less

I ran in 2 AutoX events and 2 RallyX events using the NA rad, as well as a few highway mountain climbs with steady boost for over 5 minutes at a time without the gauge so much as nudging from the half way point.

I dont have an AC condensor, that might make a difference

[SemperGuard]

An auto-x,rally-x, and canyons are not the same as a track day.

[BAC5.2]

WRX's at the track do just fine with stock radiators and 400whp.

[ramathorn]

WRX's at the track do just fine with stock radiators and 400whp.

i think were trying to gather info on a smaller than stock radiator working in our application and keeping everything cool enough.

[BAC5.2]

WRX's at the track do just fine with stock radiators and 400whp.

i think were trying to gather info on a smaller than stock radiator working in our application and keeping everything cool enough.

BD's with WRX swaps who try to run the stock Legacy radiator find out very quickly just how fast the car will overheat.

I think it's got a lot to do with airflow, fluid capacity, and thermostat control.

A set of high-flow fans will make up for a smaller radiator, to a certain point anyways.

Your friend went V-mount with an aftermarket radiator. The airflow over the new position and the radiator design could both be more efficient than stock, so a smaller radiator will do the work of a big radiator.

Personally, is it really THAT big a deal? The Koyo big radiator cools really consistently for just about any power you can throw at it (we've seen near 800whp). How much more weight would it add? Even if it holds an extra gallon of coolant, that's only, what, 15 pounds extra? That's not so bad, is it?

I bet something like a Koyo Honda radiator would work, if you absolutely want to go smaller. Hopefully, it would be at least equally efficient as the stock radiator. I would definately consider a set of high-flow fans though.

[SemperGuard]

I like that whoever deleted my post deleted it.

I remember when we didn't censor posts. It was better then.

[ramathorn]

BD's with WRX swaps who try to run the stock Legacy radiator find out very quickly just how fast the car will overheat.

well personally im running a 95 impreza radiator in my impreza with an ej22t swap. my car does not over heat and seems to run just fine as far as coolant temperature. so running a turbo radiator isnt necessary i dont think in a swap application.

[gt2.5turbo]

im pretty sure as long as you maintain stock fluid capacity and maintain a realitively unrestricted or improved flow, from stock, over the cooling surface of the fins you should be fine. i would prob pick up one of the lower temp thermostats and a decent water temp gauge so you can actually see the temps instead of relying on our stock temp gauge.... i know with my application im not going to be running a stock dimensioned radiator or location for that matter and i expect 300whp at least and i dont expect to have any cooling issues

oh and there is a huge difference in cooling efficency between the n/a radiators and our stock turbo radiators... mainly the fact that we have dual cores and the n/a's are single. I would def recommend picking up a radiator that is better than a stock single core for turbo swapped aplications as you would prob max out the efficency of that n/a radiator under most spirited driving conditions because of how much hotter a turbo motor will run compared to a n/a. not to say that you guys with swaps might be able to run temps that are just fine around town but i guarrantee that once on track or canyon driving you will see higher temps than you prob want too. and for those that can live without airconditioning there is def a lot to gain from not running a condensor in front of the Rad. i believe that koyo or one of those companies makes an aluminum version of our stock turbo legacy radiator for right around $250-300.

[IronMonkeyL255]

Koyo part # R1819 is the application for our cars.