macdaddy

I have a 93 FD with stock reman engine, stock recently rebuilt sequential twin turbos, straight pipe/K&N filter intakes, dp, 3" universal cat, Apexi N1 catback exhaust. I run 40% ethylene glycol, and use a gutted thermostat for the track. Dual 19-row Mocal oil coolers, stock intercooler, stock boost (nice 10-8-10 steady-state pattern, though it will spike to 12 or so during the primary to secondary transition). I typically run about 185-190 dF water temp cruising, but after 3-4 laps on the track I'm up to 240 dF. I've done a dyno run with wide-band O2 sensor, and am running A/F's of 11 - 11.5 for most of the power band. I have a Koyo radiator, and recently pulled it and had a radiator shop check it (not a true flow bench test, but a flush and pressure check, with an experienced eye looking at flow rates) and they said it was OK. 25% underdrive pulley on the e-shaft, stock pulleys on the accessories. Stock intercooler, though the duct has been chopped up a bit (to get the Koyo in?). About the only thing I haven't done is duct the radiator. The stock plastic undertray is in place. I have the stock nose with an R1 lip spoiler, don't know if I may be missing any shrouding the car may have had at some point in it's life.

Those of you who have "ducted" your radiator, I would appreciate some advice on exactly what you did and how it worked. I have thought about putting some sheet aluminum down on each side of the radiator from the top, like damian did for his intake heat shield, but going all the way to the plastic pan. However, with nothing fixing it to the plastic pan, I would expect it to vibrate like mad, and not seal very well. I guess I could try to install the sheet aluminum from below, and fix it to the plastic tray with thru-bolts, but that seems a little overconstructed. There's also a gap between the bottom of the radiator and the plastic tray. I've seen posts about sealing the gaps with duct tape and foam, but I can't think they're serious - there's a thin film of oil on everything, so tape won't stick, and at track speeds, I don't want anything that's going to fall apart on me.

DamonB

I have the stock radiator and a/c as well. I built simple baffles from galvanized tin that drop straight down from the edges of the a/c condensor and into the belly pan while extending forward to the nose. I carefully cut holes in them for the power steering and a/c lines to pass through. My baffles hang from the stock screws that mount the condensor and the bottom edges of the baffle slip down into the bellypan in the small gap where the bottom meets the sides. The bellypan holds the baffles in place, keeps them rigid and since they are mounted to the condensor they stay in place when the belly pan is dropped.

Works perfectly and is easily done. With the baffles in place there is literally a straight duct from the sides of the radiator all the way to the nose opening. This is much more efficient than just closing the gaps between the radiator sides and chassis as the ducts actually direct all the air straight to the radiator core.

John Magnuson

First of all... put an OEM thermostat back in ASAP. A gutten thermostat will usually allow the coolant to flow TOO FAST through your coolant system and not cool efficiently. I know that slowing down your coolant flow seems counter intuititve but it really will help you cool efficiency.

You might also want to try an 85/15 water to coolant mixture. Waterwetter helps a little bit but some claim it hurts your coolant seals.

As far as the ducting... yes it is very important to seal the gap between the bottom of the radiator and your undertray. You have two options -

1) Get some heavy duty foam and some glue (I used spray on 3M adhesive). Cut the foam to the size you want and glue it in place so that it fits tightly between the undertray and radiator.

2) You can buy a new undertray and it will come with a piece of foam already attached.

For the sides near the bottom of the radiator I recommend a similar method. Glue pieces of foam to the bottom and back sides of the undertray to that a tight seal is made.

As far as the gaps between the frame and the radiator I used foam and duct tape to seal this all up neatly.

Getting a larger Stock Mount Intercooler would probably help to. The stock intercooler becomes heat soak city after about one good lap.

-John

damian

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