Heat management

Hi everyone -- I recently bought a '98 Berlinetta (I'll do a separate intro thread once I have it home) and one of the first things I'd like to tackle on this otherwise beautiful 355 is reducing engine compartment heat. It seems like it'd be pretty easy to mitigate the problem with heat blankets on the exhaust.

My car has stock headers and cats and a Fabspeed muffler (that I'd like to replace with a stock muffler, in case anyone wants the Fabspeed). I am probably going to replace the cats right away with aftermarket 200-cell metallic core cats (if you have a pair for sale, please PM me). While doing so my plan is to wrap the cats with 1/2" thick heat blankets and wrap the headers from the union with the cats back to the collector. I would think this alone will substantially reduce engine bay temps. I'm also fabricating heat shields for the trans mounts and improved CV boot shields.

This is the heat blanket I was planning on using -- $125 for a 1'x5' roll. It's not Iconel, but it's also not thousands of dollars, and it's pretty effective stuff.
https://www.amazon.com/Heatshield-Products-176005-Exhaust-Stainless/dp/B0051UPJIC/

I've been an air-cooled 911 guy for many years and do all my own mechanical work, and the F355 is a dream car, but having almost the entire exhaust system (including cats!) inside the unventilated engine compartment is just asking for trouble.

I've done a lot of searching in the archives but haven't seen much about heat mitigation -- would be grateful for any advice or comments from this group that I've learned so much from in reading the archives.

 

Does you car have the Challenge grill ?

 

I don't, and prefer the non-grille look. Anyone know if there's been testing to see how much it lowers engine bay temps?

 

I believe Ferrari said it lowers the F355 engine bay approximately 30 degrees. Some may be able to chime in if they’ve tested this or not.

 

Interesting. Not nothing...but probably insufficient. Going from a (guessing here) 300F engine bay to 270F probably doesn't accomplish much. And it does nothing for the real problem, which is radiant heat coming off the exhaust. Heat blankets are very effective in this regard.

 

It was invented for the challenge racing series so I’m guessing it does something. Every bit helps.

 

I'm sure it helps, although a passive ventilation device like that I suspect is much more effective in track driving (consistent high speeds and more air circulating in engine bay) than in street driving.

 

My car was the first North American F355 Challenge. It was the only F355 Challenge that competed in the 1995 North American Challenge Series. It was a "test bed" that year. Its driver, Peter Sachs, reported high engine bay temperatures...


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Ferrari developed the Challenge grill as a solution.

Even with the Challenge grill, it gets pretty hot back there and it's routine for the rear deck lids to be opened when the cars finish a track session...


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So are you planning to wrap that material around the OEM header shields? It's a bit hard to imagine a clean looking solution.

To help with heat, I leave the engine bay side panels off since they act as big heat shields preventing hot air from escaping out the top. I also run a challenge grill, Gothspeed CV boots, and there are some covers on the cats. Planning to add some shielding to the muffler soon.

Definitely looking to reduce temps further as well, and open to other ideas.

 

My interpretation is that he wants to wrap the header from the header exit back to the 2 into 1 collector, not the full header.

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So what is the problem that you are trying to solve?

Are you having overheating issues/ melting components or some such?

 

Any pics of your engine bay ?

 

I don't have the car in my garage yet, getting the paperwork taken care of this week. It's in beautiful condition, and I want to put miles on it and not feel like I'm frying the engine bay. Plastics, rubber, wiring, and assemblies like alternators are subject to extremely high temps and heat cycling in a 355, and the factory heat shielding is pretty inadequate, so it seems to me that one could take a big step toward improving reliability by getting heat under control.

Yup, exactly. The way I look at it is there's 10 feet of exposed exhaust in the engine bay (call it 5 feet per side). If I can wrap the cats plus the collector section of the headers, that's probably 2-3 feet per side, or 4-6 feet total. So now half the exposed exhaust is blanketed, including the hottest part (cats). By my crude math, that's probably good for a 50% reduction in engine bay temps. I've got an IR thermometer and will be doing before and after tests.

 

You could see if the FabSpeed header blankets will fit over the stock headers. I agree about the heat issues. When I want to heat up my garage I start the car and run it outside for 10 to 15 minutes and then bring it back in. In five minutes the garage is noticeably warmer. There are lots of wrap materials available from Design Materials I think. Good Luck show us the before and after I would be interested in how this turns out.

Laserman

 

One thought I had, purely a mental doodle, was that someone could replicate the heat exchanger design on air-cooled 911's, since the 355 headers/collectors already have tinwork surrounding the exhaust pipes, like a 911. On a 911, the header/tinwork is called a heater box since it's how you warm the cabin of the car. There's an opening in the rear of the heater box, air from the engine cooling fan is pumped in, and there's an opening at the front of the heater box where the hot air, which has now passed over the header pipes, exits and is either dumped out under the car or sent into the cabin.

On a 355 you could theoretically do something similar with a small electric fan at the front providing the airflow. And of course in this setup the air would exit at the back of the collector through the engine grille or below the engine. If a Singer-type company wanted to start redesigning a 355 this would be a cool thing (sorry, bad pun) to try.

 

Be interesting to see what you do and what the difference is.

I’ve not had any issues with my 355 and there are no heat management arrangements other than stock. If I had issues I’d also be looking at high capacity radiators and increasing airflow through those.

 

Agreed - my 355 is stock except for the Tubi muffler and no heat management issues. I do have a challenge rear grill.

My 308QV on the other hand, that car ran HOT. By comparison, my 355 is quite pleasant to drive.

 

The heat has to go somewhere. It will either conduct both toward the engine and toward the muffler. It will also get transferred to the exhaust in the form of higher exhaust temperatures. I would be careful and consider the impact of these side effects. You don't want to overheat other stuff.

 

Yes, good point. It's why I'm not wrapping the exhaust manifolds -- those need all the help they can get (mine are stock). But I figure the collector and cat sections are fine, and the heat that isn't radiated into the engine bay will stay inside the exhaust resulting in hotter exhaust gas temps, which exit where they should, through the tailpipe. Or so the theory goes. I'll know soon enough.

 

Inconel is expensive but best way to lower temps. I had Capristo and Fabspeed blankets. The inconel shields were the best by far then Capristo. I didn't think much of the fabspeed blankets. If you are keeping the car and you put miles on it
the inconel shields eill save engine components. There is a reason raced cars use them
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Thanks Bob -- am gonna do something like that when the time comes for aftermarket headers, but mine are still good. I'm leaving them alone for now and focusing downstream, as I figure putting blankets on the stock headers will rapidly accelerate them failing.

 

Bob, is that a stock/OEM shock pictured or something else?

 

I think heat reduction/isolation is a worthy cause. Just also remember to think about the engine compartment at speed.

Sure, stuck in traffic all of the heat that isn't contained will move upwards to heat soak other components but not a huge problem IMO.

The plenums are composite so they aren't holding heat, engine is of course liquid cooled and as soon as you are moving there is a ton of airflow through the engine compartment washing the heat rearward and out.

Everything you intend to wrap is behind the engine so not -much- of a benefit unless you intend to operate the car at very low speeds.

Headers I think are the low hanging fruit. Insulate those and you are doing well. Cats are a huge source of heat but still, behind the engine.

 

The shocks are Motons

 

CV boots, motor mounts and a few connectors have been the only victims of heat in my 355. The engine runs cool, even in a SC summer. I have Tubi headers and some CV shields that Gothspeed made. Yes, the engine bay does get hot, but I havent seen any major issues like overheating.