Tornado GT40 in Texas

Dr. Bob Woods

Member
GT40s Supporter
John,

Thanks for the question. Actually, I'm almost through. I have been devoting all my spare time to building instead of updating my build log. I plan to do that when I get through. I'm trying to make an April drive day. I have a lot of interesting things to report, but no time to do so...

You guys are welcome to come by and see the progress.

-Bob Woods
 

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Dr. Bob Woods

Member
GT40s Supporter
Mike,


Good catch. I originally had 50 mm bellmouths on the throttles. The photo shows the 50 mm bellmouths. I switched them out for 35 mm bellmouths because the 50s wouldn't clear at all with the filters on. Although I haven't installed the rear glass yet, it appears that number 8 (the farthest back) is the only one that is going to barely touch unless the glass is more curved than I think. I'm planning to slice the rubber part of that air filter and then bond it back together.


I'm sure others have had this problem. How did you solve it?


-Bob Woods
 

Dr. Bob Woods

Member
GT40s Supporter
Mike,


Good observation. I originally had 50 mm bellmouths on the throttles. That is what is shown in the photos. I switched them out for 35 mm bellmouths because the 50s wouldn't clear at all. Now, it appears that number 8 (the farthest back on the left) is the only one that might just touch the glass.. I haven't installed the rear glass yet, and unless it is more curved than I think, I will have to modify #8. I'm planning to slice the rubber part of that air filter and then bond it back together. There are some other approaches that would work.


I'm sure others have had this problem. How did you solve it?


-Bob Woods
 

Dr. Bob Woods

Member
GT40s Supporter
Mike,


Sorry for the double post previously...


I put the rear window on and it is curved just enough to clear the #8 air filter with a 1/4" to spare. I'm glad I ordered the 35 mm bellmouths.


-Bob Woods
 

Dr. Bob Woods

Member
GT40s Supporter
Heat Shielding

I had two heat problems with the car. First, the exhaust was too close to the fuel lines. On two occasions, upon driving home, I couldn’t use more than a touch of throttle without the engine dying. I think the hot exhaust was heating the fuel supply and return lines and was vaporizing the fuel. The first photo shows the proximity of the fuel lines to the exhaust headers. Unfortunately this photo has the turkey pan installed, but you can see how close the perhaps 1000 degree exhausts are from the fuel lines.

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I built a turkey pan to attach to the throttles. This required a lot of trimming to get the pan around the machined surfaces of the throttle bodies. There is also an aluminum lip going down below the throttles to the base of the intake manifold.

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My first attempt was to simply put the Design Engineering Inc. Heat Shield with fiberglass and self-adhesive on the back of the turkey pan by the exhausts (as shown in the first photo). That didn’t hold up, so my second design was to use two aluminum plates with the Heat Shield and an air gap between them. If you look closely you can see the air gap. That seems to work fine.

1543805949478.png


The second problem was the heat going into the rear clamshell. I did use both LizardSkins on the rear clamshell. But the fiberglass being about 2 inches from the exhausts headers meant that a lot of heat was going into the bodywork despite the LizardSkin. As a matter of fact, the LizardSkin flaked off in an area just above the headers by the turkey pan. This is in response by a comment made by Rick Muck on Bill Kearley’s post #21. Not only did the LizardSkin flake off, but the outside temperature of the clamshell was excessive. I’m surprised that the fiberglass or paint wasn’t damaged.
https://www.gt40s.com/threads/bills-cav-193-build-canadian-made.52505/page-2

My solution was to build an aluminum plate to shield the rear clamshell from all of the exhaust headers. I put the Heat Shield fiberglass insulation on the other side of the aluminum plate to provided even more insulation in addition to some natural air gaps. Since I couldn’t drill holes in the painted part of the clamshell I bolted it in three places. I used bolts in the muffler vent plate on the rear clamshell, on the vertical tire shield, and the interior lip in the front of the clamshell. Now, the outside of the clamshell is not blisteringly hot and is somewhat cool. It also reduced some of the noise form the engine bay into the cockpit.

1543805973068.png


I consider both of these as serious problems. I’m glad I fixed them.
 
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Randy V

Member
Admin
Lifetime Supporter
That was a ton of work (well done I might add) to mitigate the heat issues that plague all these cars. I had planned on installing a polished stainless steel “reflecting panel” in the rear clip similar to yours and I believe Mitch is planning to implement it.
Great job!
 

Bill Kearley

Member
GT40s Supporter
Randy nailed it, a ton of real nice work Bob. I had a concern about hot fuel as well. I won,t go into all the distributor/fuel rail fitment problems. In the end I built my own dist. and have the fuel lines up front. As for hot exhaust pipes I think I will be forced to cut the clam and build a cake pan size riser under the window. My no. 7 pipe may as well be touching. While I'm here, could you tell me what air filters you have.
 

Dr. Bob Woods

Member
GT40s Supporter
Randy,

Thanks for the compliments. Yes, it was a big trial and error process. I used framing matt board and trimmed several times before I transferred it to the aluminum.

I too bought a sheet of stainless steel for that purpose. However, I think the aluminum will reflect the radiant heat just as well and the Heat Shield fiberglass insulation plus aluminum should be better insulation than the stainless steel. There are also some air gaps that help as well. The steel is heavier and probably would have to be mounted before painting or you would have to roll some beads in it to make it stiff enough not to deflect under vibration. I should have put some rolled bead stiffeners in my aluminum, but the bend at the back might be stiff enough.

These are in my opinion some serious issues of the exhaust heating the fuel and the body work. I'm surprised that there is not more discussion about it on this forum. Just driving calmly around the neighborhood, the clamshell was blisteringly hot, I'm surprised that it didn't damage the paint. It did melt some wires that I have running along the vertical tire covering wall.

Bill, I bought the K&N air filters from Roush Industries. It is part number SP2988. Roush is the exclusive dealer for them. They are sold through the crate engine department (option 3 if you call).

I would recommend that you handle the exhaust heat before you paint the body. I still have the templates for the turkey pan and clamshell shield if you want to borrow them.
 

Bill Kearley

Member
GT40s Supporter
Thank you Bob. We are getting close to start up and I have to make a decision quick, i'm leaning toward modifying the clam under the window.
 

Ian Anderson

Member
Lifetime Supporter
Very nicely done Bob.

At low speed you get very little airflow under the clip.

I fitted a 250 cfm 4 inch marine bilge room fan to each side and when slow toggle switch them on which makes a huge difference in the under clip temperature!

Ian
 
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