Dear all,
I just bought an FD3S from 1994 and it is completely stock. Not sure if it is normal as altough it was always my dream to owe one, I never had experience with rotaries. Is it normal that the engine bay, bonnet and front bumper are super hot after a 45 min ride? Cooling temp on dash was very stable in the mid range. If normal are there any mods I can adopt to improve cooling as i could barely touch the bonnet hinge.
Thanks guys any suggestions will help

 

Congrats on the FD and welcome to the board. These engine bays will always be hot. Is your car a LHD or a RHD? If it is LHD, the single best thing you can do for your engine other than maintenance right now is to replace the precat with a downpipe. Those generate and hold a ton of heat in the engine bay. As for making the engine bay cooler, aside from the precat, you can go with an aftermarket hood to release heat from the engine bay but it isn't totally necessary.

Since you aren't very familiar with these cars. Take a look at the FAQ and sticky sections in this 3rd gen section. You have days of reading and research which will most likely answer 90% of your questions and will get you familiar with some of the basic things with these cars that are oh so important. My car is almost bone stock (was until very recently) and I live in Florida. Its RHD so I don't have the precat to worry about for extra heat, but that is how these cars were designed and they will hold up to it as long as you make sure everything is in good condition. I would suggest completing all maintenance and verifying proper operation and condition of everything in the car before you really flog on it. 30 year old rubber doesn't do well with the high heat these things run under.

You also cannot trust the factory gauge, it does not give you an actual temp readout. As you will find in the sticky section, having real temp, pressure, boost gauges are one of the things you should have for your car. The temp could swing something like 30-40 degrees F without really moving the needle much on the dash. Better to know the accurate temp. There are plenty of cooling mods, like the FC thermo switch which will help keep the engine running cooler as the factory is designed not even to kick the fans in until around 210-220 degrees F IIRC. Most people like to run around 185.

 

Excellent advice there... all of it.

To add, yes it's completely normal on a stock fd for the hood and hood prop to feel like hell. So long as you have an unvented hood, a pre cat, a stock mount radiator and stock fan activation temp, it will be that hot. So it's something that should be addressed.

At a minimum you should buy a power fc for the sole purpose of being able to drop the fan activation temp to a more reasonable ~87C. The thermoswitch mod is cool but 95C is still way too hot to run the fans. Better than stock but still too hot. Get in the FAQ and read and never stop reading.

If you are unsure, ask. Do not shotgun mods or buy random parts without first understanding WHAT you're buying or WHY. It's a lot easier to ruin an fd than it is to buy one. Cooling is the primary battle with these cars. Focus your efforts around thermal management and everything else just falls in place.

 

Thank you guys for the great info. Mine is also a RHD below picture of my pride and joy. Replacing the hood is not an option since in our country this car is registered as classic and there are very strict rules on modifying. To be honest what I had in mind is a power FC and a Mishimoto or Koyorad radiator upgrade. But I just got it 2 days ago and need to familiarise myself with the engine bay

 

That is unfortunate. What about modifying the stock hood? Zkmotoring sells a FEED style insert that can be grafted in.

Do not buy the mishimoto radiator. Its shiny trash. Koyo n flow is the only radiator that should be considered for stock mount applications. You can further boost this with the rx8 fan upgrade. Jp3 sells a kit for that so you don't have to source everything individually.

Keep in mind, with a non vented hood and a stock configuration radiator, your battle against temps can only go so far. The only real way to control it is v mount AND a hood with some kind of hole in it. Pursue cooling upgrades above all else. Longevity and reliability are directly related to cooling related mods.

Delete the ast if so equipped.

 

Excellent.

If you don't have a stock 2nd oil cooler that is a great cooling mod also. Pic looks like you may have a cat-back exhaust already. A straight-thru cat back can clear a lot of heat out with the exhaust.

 

Engine bay heat and the engine’s internal heat are largely two different things. A vented hood is fine but decent quality ones are expensive to buy, ship and paint and everyone I’ve seen other than a Mazdaspeed version had serious fitment issues…although some of that could have been helped with knowledgeable install. Bay heat is at it’s worse and rises when you stop/park. When practical just open the hood. Don’t be tempted to get a turbo-timer. You have a water cooled turbo and it does nothing for bay heat.

Since the car is new to you the earlier suggestion to consult the FAQ’s is where to start, and not just with heat abatement questions. Search for reliability Mods. Some threads will be old but the info will be just as valid.
Heat wrapping the downpipe is probably easiest for the newer owner. It’s not a walk in the park but you can access almost all of the DP with wrap. It’s cost effective, reduces radiant heat in the bay and less expensive and easier than removing the DP for a heat coating. Besides, you still have a big hunk of iron turbo manifold which is probably the main source of bay heat.

For controlling engine heat I absolutely agree with installing an aftermarket temp gauge or installing a standalone ECU like a PFC to both lower threshold fan initiation AND monitor temps. I also agree that if you are COMPLETELY stock, invest as soon as possible in a quality all-metal radiator. The plastic end-tanks on the stock version can and do fail catastrophically with age and heat cycles. In addition to Koyo, Fluidyne makes a quality radiator that’s more than adequate for a stock or near stock car. The Koyo is slightly larger but some have found the Fluidyne easier to install. Deleting the AST is fine, I did myself years ago. But there is a proper way to do it. Search the forum and the FAQs for more info. Option #2 is to keep an ast but like the radiator, purchase an all-metal version.

 

Thanks for your feedback

 

So I took your advice and starting searching for Koyo rads but it seems like its impossible to find any in europe. What I found is Mishimoto but you told be it's crap right? Any ideas from where I can get the best deal for a Koyorad?

Thanks guys

 

There are plenty of vendors that ship internationally. Any one of us can get the koyo to you although it will be very expensive to do so. The box isn't very heavy but it is large. Shop around for the best price. Do not settle on the mishimoto for any reason. You'd be better with no radiator at all.

 

No idea about best deal but there are a few rotary shops in UK. Not sure about rest of EU. And any Koyo dealer near you should be able to order you one.
https://www.racingbeateurope.com/maz...tor-1432-p.asp
Haywood Rotary is in the UK.
Essex Rotary
Wankel Shop in Germany I think

 

I've also been concerned about cooling--and am running a relatively stock setup.

@FDAUTO, I have this Fluidyne Race Radiator, which is also a drop-in replacement like the Koyo. I thought this was a good option, would be interested in hearing more detail if it isn't.
Also, I just reversed the AST delete on my car with this aluminum OEM style option. Is there some downside to an AST other than the hazards of the plastic originals?

 

Fluidyne is great. I have one in my "other" fd. It's been in there since I bought the car in 2015 so I don't know how old it actually is but temps are great..... always. It's been used in a front mount configuration this whole time with stock fans.

Putting the AST back in the car....... I will summarize by saying, there are more productive ways to waste time and money. What's important is you feel good about doing it and that's what makes it worth it.

 

i have not been very happy with the Fluidyne for a few reasons

the core is a little smaller than the koyo N-Flow. I do prefer the Koyo N-Flow over the fluidyne . temps at the track were lower on the N-Flow than the fluidyne. While there were other contributing factors for my decrease in the coolant temps there was a point where i was comparing apples to apples with the same exact setup on the koyo VS the fluidyne. I wouldnt say the temperature difference was alarming. i got rid of the fluidyne 7-8 years ago so i dont have the numbers handy but if memory serves i was pushing around 105C on the fluidyne vs around 100C on the koyo N-Flow

and the welded mounting brackets can cause some issues on certain setups. it really sucked on my V-mount setup but i am not saying that it would suck on every Vmount setup.

being a european myself i know how the part availability feels. just find a shop that ships to Europe. pay the VAT and the shipping associated with it and call it a day.
Alternatively, you can use the Driftshop. 🚗💨 Motorsport Car Parts Shop, Street, Race, Drift | DriftShop which is in France. Me and friends used them several times with good success.
I dont know where you are located but if you are in mainland Europe it should be relatively cheap to ship
Bare in mind. The models for the radiators for the US market VS the european market vs the Japanese market are different. you most likely wont find an N-flow radiator there (unless the company imported it from the US) so it will be another equivalent model

 

Can't argue with the larger capacity of the N-Flo but I've run Fluidyne in many cars over the years and have never had an issue. It would still be my go-to radiator in FDs if they still made them but they don't. Maybe because I've always used them in stock configuration rather than V-mount I didn't have the cooling differences that you saw? I did have one in one of my FCs with a horizontal mount setup but still had no issues. If Fluidyne still made them for the FD I would purchase one over the N-Flo strictly due to the fitment and constraints we run into with the thicker core of the Koyo.

 

Ran my Fluidyne in the stock location on my mildly modified car for 20 years or so. I used the S5 FC thermoswitch to initiate fans on the stock fan assembly at a lower temperature (and only later added a PFC). When I installed a PFS SMIC the move to delete the AST was sort of forced on me as its AST mounting tab location was designed for the stock version and that was a deal killer back then. I really like the look of yours. If those would’ve been available I might have kept mine too. Still, no issues with my ast delete, especially using Banzai Racing’s metal filler neck extension. Temps were always rock solid. Stock T-stat, 50/50 distilled water to coolant changed every couple years. In addition to simply rinsing/cleaning the face of the AC condenser and radiator, I used upholstery foam in the gaps around the radiator and IC duct. If you look up in the nose of the bumper you’ll see what I mean. I also ran a simple boost-activated water injection system that eliminated the temp spikes I used to see during the harder WOT boost episodes. I once c removed and cleaned the overflow reservoir and periodically checked to be sure it was at the ‘full’ mark.

 

the difference in temperature I would say is negligible. I did not have an issue running the fluidyne despite that minor difference. it could be the difference of many things that may not be radiator but using the fluidyne with the HKS V-mount setup was a major PAIN .
The mentioned temperatures were at the track

 

I can see that. Any time I build a V-Mount setup, I also do a custom radiator rather than trying to make the stock one work which it was not designed for. That way you can properly fit and mount it with great ducting and simplified proper hose routing. The more horizontal you run the radiator, the more important it is to build a splitter between the intercooler and the radiator to make sure both exchangers are getting enough air flow. Air will take the path of least resistance so if the intercooler core has less fin density and a straighter ambient air path, the radiator will receive less air and be less effective at cooling the engine but intake temps will be down. I can't believe how many V-Mount setups I have seen where there is just plain no ducting, totally open on the sides which means neither exchanger is getting proper airflow through them but rather most of the air is going around them into the engine bay.