Split Front Mounted Radiators

[kabacj]

I was able to get a couple of things completed today with the biggest milestone being getting the hood brackets progressed and the hood mounted.
The hood opens and closes like a champ!
The hood brackets still need to be powder coated and the base plates glassed into the hood.
The tube work has been cleaned up ad painted so it is time to start putting things together for the last time and finish off the aluminum close out panels.

I like your hood hinge setup Dave. I have been thinking about the hood hinges on the stock car. Since the pivot point is behind the light buckets, as the hood tilts up the area below the pivot moves downward. This is fine if you have the stock splitter. I wanted to hinge the hood but also run a solid floor that extends out to the splitter. I think your idea of hinging the hood at the lower edge would solve this problem. Thanks for sharing your design.

John

[Fraser D]

I like your hood hinge setup Dave. I have been thinking about the hood hinges on the stock car. Since the pivot point is behind the light buckets, as the hood tilts up the area below the pivot moves downward. This is fine if you have the stock splitter. I wanted to hinge the hood but also run a solid floor that extends out to the splitter. I think your idea of hinging the hood at the lower edge would solve this problem. Thanks for sharing your design.

John

John,

I will take some detailed photos when I disassemble for final install to give you a better perspective.
One key, (for my application anyway) aspect that is missing is the slide limiter which allows the assembly to slide forward a little over 3” to clear my splitter tray and ducting before tilting up. I will update the thread once I complete those pieces.

[Fraser D]

I was able to squeeze a couple of hours in today and completed the screens/mounts for the radiators.
This is the stainless steel wire mesh that I purchased for the first attempt at split rads.
These are the ones that will protect the radiators from big bits of rock.
I will just wait and see how much trash ends up between the screen and the radiator before I take any further action.
Installing louvers once everything is closed out will not be a big deal if it comes to that.
My plan this weekend is to get all the close out panels made and installed along with the radiators themselves for the modified front end. Hopefully get the headlights installed and wired but lest see how far I can get.

[Fraser D]

Well four more panels to make, a few hundred 1/8” holes to drill, a little painting and lining and it’s done! Maybe ;-)
Oh and I now have a trunk.
Getting close now.

[Aman]

whoa, nice work! Great idea, that is going to be very handy

Aman

[Fraser D]

A little progress this week.
Panels coated and installed for the final time.
The trunk is insulated but I will wait until I am further progressed with the body work before installing the carpet.
Radiators installed, filled and car run with no leaks in the system.

[GTM]

This is likely going to be on my list of "must-do's" Going to go through the photobucket and may ask for more info later. Thanks for sharing!!

[Fraser D]

This is likely going to be on my list of "must-do's" Going to go through the photobucket and may ask for more info later. Thanks for sharing!!

Thanks and let me know if you need any dimensions or closeups.

[Demthios]

Looks Like you might have started something here, I can see my self attempting to follow in your foot steps with this set up as well. Thanks for spear heading it for us! Keep up the awesome work

[Fraser D]

Looks Like you might have started something here, I can see my self attempting to follow in your foot steps with this set up as well. Thanks for spear heading it for us! Keep up the awesome work

When you get serious about taking this path get in touch as there are some improvements that I can share.
Once I finish I intend to write a bit of a write up covering the pros, cons and improvements .

[Taz Rules]

I don't even have a kit yet, but I'm thinking seriously about following your lead on this when I get one. I have a few questions though.

1. Where will you pull the airflow from? Will you duct it from the center hood opening? Or close that up and open two intakes closer to the corners?
2. Where will you vent the hot air to? Will you channel it up over the wheel to fender vents? Or duct it to central vents as exist now on a Gen 2? I'm assuming you don't want to vent that hot air past the front brakes and out the wheel well.
3. Where is the AC condenser? Can you split it in two and set it up with the twin rads? Or do you still plan to have a single, center mounted unit?
4. Will there be room for the battery forward of the new trunk? This could create some much needed space behind the steering rack for AC and electronics packages. Also, as I understand it, bringing weight forward on a GTM is a good thing, handling-wise.
5. How will the weight of the radiators being further outboard affect steering and handling?

As a final note, check out the Photoshop stuff I did on the FFR forum in collaboration with Mike on his interior. If you like it, let me know and maybe we can work together on some front end designs. This concept really intrigues me.

[Fraser D]

I don't even have a kit yet, but I'm thinking seriously about following your lead on this when I get one. I have a few questions though.

1. Where will you pull the airflow from? Will you duct it from the center hood opening? Or close that up and open two intakes closer to the corners?

DF. I still need to fiberglass the intakes/duct but this should give you an idea.

2. Where will you vent the hot air to? Will you channel it up over the wheel to fender vents? Or duct it to central vents as exist now on a Gen 2? I'm assuming you don't want to vent that hot air past the front brakes and out the wheel well.

DF. For now the hot air will just flow into the wheel well but at some point I intend to duct it around the wheel and through the wheel well vents. I need to get a better idea of flow rates etc to make sure that I don’t create a heating issue. More time with a beer in hand while scratching my head plus some time on the road to see how it is all working out.

3. Where is the AC condenser? Can you split it in two and set it up with the twin rads? Or do you still plan to have a single, center mounted unit?

DF. I am going to try the center condenser approach to see if I can get enough heat exchange with the air exit being via the brake cooling ducts that I am installing. A plus is that there will not be any heat soak from the engine or radiators for the condenser to contend with.
The center air intake has not been cut yet. You could split your condensers and run one with each radiator as this will work.

4. Will there be room for the battery forward of the new trunk? This could create some much needed space behind the steering rack for AC and electronics packages. Also, as I understand it, bringing weight forward on a GTM is a good thing, handling-wise.

DF. If you did not have your AC condenser in the center then you could utilize that location for a battery.

5. How will the weight of the radiators being further outboard affect steering and handling?

DF. The mathematical answer is yes but I doubt that I would notice any difference either good or bad.
I want to add a couple of smallish canards in the same area as the Gen 2 hood to help with the high speed aero.

6. How is the headlight clearance?

DF. This photo does not have the top of the radiator closed off but the finished gap at its smallest is ¾” between the radiator and the light bucket.

As a final note, check out the Photoshop stuff I did in collaboration with Mike on his interior. If you like it, let me know and maybe we can work together on some front end designs. This concept really intrigues me.

I would appreciate that as the original openings were for the previous radiator setup which would have been a gradual profile and now look a little odd for rev 2.
Let me know if you have any other questions as I learned a lot through this process and I have no issues passing on how I would make this design better that what I have.

[Fraser D]

Well I had a go at making the radiator intakes today and only glassed up the passenger side intake along with the hood mount backing plates.
I would appreciate any feedback and comments regarding how this looks as I am afraid the style gene is completely absent from my DNA.

[Fraser D]

Well I took Ash (AKA Taz) up on his offer to play around with the front options in photo shop and this is what he came up with. He took a little of what I have already and added a couple of options of his own and I have to say that the results really helped me to fully picture the end result.
There are still a couple of technical issues to resolve in order to make the best looking version work, (large center intake for the AC condenser) and that primarily is how to pass as much of the air as possible that that hole will collect.
Current plan is to run dual 3" brake ducts (4 x total) from that cavity and let them both exhaust into the wheel well for now then later hook one up to each of the front brake calipers.
I have found a few options regarding bar LED Fog lights that I am looking to install under the top edge of the radiator intakes.
Thanks Ash for taking the time to help me out. Very much appreciated.
For the builders like me who are not afraid of making something different but are challenged in the style department I strongly recommend using tools like this and talented folks like Ash.

[Fraser D]

I had a quick hour and a half this morning and knocked out the drivers side intake.
One more thing tick'd off.
Still need to clean them both up and smooth them out.

[Desertrunner]

Dave I ment to post a couple of weeks back were I found some Porsche have split front radiator and they run them in parrallel. If its important I can go look for it a again.
Tony

[Fraser D]

Tony,

I am interested to see how they do it if you come accross that information again.
Thanks

[Desertrunner]

Its diagram of the plumbing, hope it helps Dave. What I also think is interesting is the way the oil coolers work.
Tony
996tt_cooling.png

[Fraser D]

Its diagram of the plumbing, hope it helps Dave. What I also think is interesting is the way the oil coolers work.
Tony
996tt_cooling.png

Tony,

Thanks for the diagram.
Interesting how they run the pump so that it pushes through the engine.
I am still running with temp plumbing so may see how this compares to the temps I am getting now.

[Desertrunner]

Hi Dave,
Yes its a interesting doc,

Both Subaru and Porsche have 2 things in common, they have the pump pushing through as you say which I tend to agree is a good idea, the other which I don't agree is they both have the thermostate on the suction of the pump.
Both Porsche and Subaru get cavitation and poor cooling control due to this point. In the case of Porsche they have tank 7 to get rid of the air.
The logic behind having the thermostate on the suction of the water pump is that the engine will always get in spec tempreture controled coolant. Which sounds great but in reality doesn't work for a whole lot of reason I won't go into here.
The Porsche oil coolers are really smart becasue once you have your engine at the right temp the coolers make sure the oil is at the right temp as well. People fail to realise that with the Porsche oil cooler design they are infact temp controls as they both heat the oil and cool it. The problem with normal external oil coolers is that unless they are fitted with a thermostate you can blow the engine from oil being to cold.
Keep well, great project.
Tony

[Fraser D]

Starting not to look like a jigsaw puzzle anymore.
Still a ways to go. Wheel vents next on the list.

[Fraser D]

Actually got a couple of hours in the shed today.
The front is almost done. There is a lot of detail work that the photos don’t really show but all the front wiring had to be completely redone and re run, (which is now done except for a few weather pack connectors).
The splitter tray is now mounted and I have one of the fan shrouds completed and the other shroud cut out ready to bend.
The hood mounting brackets have been cleaned up after being fiber glassed into the hood and bolted back together.
The hood itself still needs some cleaning up with a couple of spots on the radiator intakes to be filled with resin.
I have a different style of bulb seal ariving during the week as the FF5 stuff is simply falling apart.

[Fraser D]

Getting very close to completing the front section and the split radiator modifications.
Wheel well vents installed with the fan shrouds and AC condenser to complete before track testing to see how the cooling and aerodynamics have been changed.

[RM1SepEx]

Dave, where did you get your wheel well/fender vents? I'm considering a similar twin radiator mod for the 818...

Thanks

Dan

[Fraser D]

Dave, where did you get your wheel well/fender vents? I'm considering a similar twin radiator mod for the 818...

Thanks

Dan

Dan,

The Factory Five GTM shop sell them for $199 + shipping and handling
http://www.factoryfiveparts.com/gtm-fender-louver-set/

[Fraser D]

I made some modifications to the fan shroud to allow at speed air flow to bypass the fan opening.

[RM1SepEx]

Dan,

The Factory Five GTM shop sell them for $199 + shipping and handling
http://www.factoryfiveparts.com/gtm-fender-louver-set/

Its a pretty sure bet that they won't fit the 818 fenders...

[WIS89]

Dave-

Build is looking pretty awesome! I really enjoy watching your progress on the split radiators. I hope it exceeds your expectations on the track! Thanks for documenting it and putting it here for us to see. Really great work!

Regards,

Steve

[Fraser D]

Its a pretty sure bet that they won't fit the 818 fenders...

Dan,

A couple of folks have made their own version, (or their body guy did) and I think that one or two of the shops will sell them.

[Fraser D]

Dave-

Build is looking pretty awesome! I really enjoy watching your progress on the split radiators. I hope it exceeds your expectations on the track! Thanks for documenting it and putting it here for us to see. Really great work!

Regards,

Steve

Thanks Steve,
It did not end up being the configuration that I started out with which is the fun of starting out with only half an idea :-)
I am shooting for a track day during the 3rd week of August at one of the local tracks with still plenty of work to complete.
As I still consider this to be a bit of an R&D project a couple of aspects will remain unrefined until I am completely happy with the setup, (especially the front aerodynamics).
Bondo and undercoat will be the paint scheme for a while I am afraid.
So if I have not forgotten something stupid I will have some real data on the setup after that event.

[kabacj]

Dave the setup looks excellent.

I am sure if the setup works well on the track it will also work well on the street. The track is a great way to both push yourself and your design.

One thing I found on the track that I did not expect might help you out.

I was surprised by all of the rubber bits that end up finding their way into cracks and crevices. I have not yet installed the splash guards on the front fenders and i end up with a pile of rubber bits in the foot wells after every weekend.

When you plan on hitting the track you might want to consider using a fine mesh screen to keep the rubber bits out of the radiators both front and back.

John

[Fraser D]

Dave the setup looks excellent.

I am sure if the setup works well on the track it will also work well on the street. The track is a great way to both push yourself and your design.

One thing I found on the track that I did not expect might help you out.

I was surprised by all of the rubber bits that end up finding their way into cracks and crevices. I have not yet installed the splash guards on the front fenders and i end up with a pile of rubber bits in the foot wells after every weekend.

When you plan on hitting the track you might want to consider using a fine mesh screen to keep the rubber bits out of the radiators both front and back.

John

Great advice John

I was planning on repurposing the FF5 mesh from the original radiator hood exhaust for my radiator intakes
Do you think that the mesh size will work for the rubber issues?
I had not planned on any other mesh other than the stone guard that I currently have for the back of the radiators but will change that now
Funny that you mentioned getting rubber inside the cabin as Linxs and I were going over the car looking for heat entry points and the foot boxs especially around the top are wide open.
I need to invest in an assortment of different seals to take care of that.
Thanks for the feedback

[kabacj]

Great advice John

I was planning on repurposing the FF5 mesh from the original radiator hood exhaust for my radiator intakes
Do you think that the mesh size will work for the rubber issues?
I had not planned on any other mesh other than the stone guard that I currently have for the back of the radiators but will change that now
Funny that you mentioned getting rubber inside the cabin as Linxs and I were going over the car looking for heat entry points and the foot boxs especially around the top are wide open.
I need to invest in an assortment of different seals to take care of that.
Thanks for the feedback

Hey Dave,

yes the factory five mesh has roughly 1/4 inch holes if I remember correctly. That might be just a little big to block everything but the vast majority of the bits are 1/2 to 1 inch long by 1/8 to 1/4 inch in diameter.

I ended up using duct tape to block all of the openings where the aluminum touches the bodywork in the front wheel wells. Bulb seal would most likely work in these places.

I wanted to maintain the vent where the leading edge of the door and the front fender meet.I would think you also would want to keep this airflow path open as it exhausts air from the front fender. I can tell by the amount of brake dust on the leading edge of the door that air is definitively following this path.

The down side of not having splash guards of course is water in the rain and the rubber bits.

The other thing to consider is the aluminum you might add under the nose.

Without any aluminum you are going to have plenty of airflow as air will exit under the car and any debris just falls out on the ground. If you add aluminum to channel the air then you might need to be more concerned where the air exits and what enters that area.

You are going to have a blast on the track.

John

[LCD Gauges]

Awesome! I just realized by glancing through your first page that you've redesigned the rad layout. Version two looks much better!
You may be the only one that will have effective use of the louvers over the tires.

By the way, I'm jealous of your trunk space.

[Fraser D]

Well there is something to be said for spending a little time recuperating from surgery to get the creative juices flowing. The bad part about recuperating from surgery is that I can’t do the work myself for the next couple of months.
Continuing on from the physical mounting of the radiators it became a challenge to make the brake ducting and the AC condenser operational while the hood was in one piece.
I looked at the different approaches to making the hood two piece that have been tried on GTM’s so far and different production cars and decided on the approach in the below photos.
A jig was made to align the hood when in two pieces to allow the fiber glassing of the weather-strip and any reinforcing, (although the pieces are very thick and did not move once cut).
The pieces are just laid in place with no alignment or positioning and I was surprised to see that the natural lay of the main hood piece is almost perfect.
Having the front piece separate from the hood itself gives me a lot more options for the radiator intakes, (profile will change) and the center AC and break intake, (yet to be cut).
So what stands between me and success right now will be my ability to not backseat drive and piss off the help
It is early in the process but I am very happy with how it is turning out.

[Fraser D]

Taking the next step in fiber glassing in the weather strip overlap and I am not sure if the panels or my jig have moved some or both but the two pieces are not settling in as well as they did previously. I will leave them on the jig overnight and all day tomorrow to see if the alignment gets better.
If not I will pull them back into position with some screws and glass in some reinforcing strips to hold the shape.
I have all the mounting points identified for the two pieces and some design drawings for the hood hinges which are just waiting on material.
The process of putting things on the car then pulling them back off is getting old but I only have myself to blame.

[Fraser D]

The day started off with a thunderstorm and local flooding so I was not very optimistic at getting anything done today but managed to get the fiber glassing for the weather strip completed.
I will trim the fiber glass back in the morning, finish the mounting of the nose section then make it all pretty.

[Fraser D]

My shoulder is starting to feel good enough to do a little light work so I made some progress with a few things.
The AC condenser is ready for a date with the TIG to weld in the fittings and mounting brackets.
I have rough cut the center opening that will supply air to the AC condenser and cooling air for the front brakes via some ducts. The opening still needs to be finished with a lip fiber glassed in.
The radiator opening are getting a little tweaking. The shape is having all the angled corners replaced with radiuses so I made up some fiberglass pieces to graft in. One corner down two to go.
The internal frame for the mounting and support of the front clip is almost done along with the hood hinges.

[Taz Rules]

I think the rounded corners will really make a difference. They make it look more refined. I like it

[kabacj]

Looking good Dave. I am looking forward to joining you creating some custom GTM bodywork features.