My 1883cc Porsche 356 912 Blog

Chronology of a hot-rod street Porsche 356/912 1600 to 1883cc conversion based on LN Engineering's Nickies big bore kit.

Wednesday, August 16, 2006

More testing with the euro tin

Now that I have the lower euro-inspired cooling tin in place, I decided to take the car to Chicago yesterday. A little bit of highway driving mixed with equal parts of traffic would be a great chance for me to see how the tin would affect the oil and head temperatures. 

First off, it took a good 10-20 minutes longer for the oil to get up to 180F. Secondly, once I got going and was cruising with some fairly decent rpms, the oil did manage to warm up to 190F, but as soon as I reduced speed, it quickly decreased to 180F and for the first time I've seen, it actually fell to 175F during operation.

Lastly, head temperature. I would have not believed it with my own eyes but I have a head temperature gauge as my proof. With an outside temperature of about 82F, I was running on my way to Chicago 315F head temperatures while holding in excess of 65mph and 4200-4400 rpm in 5th. Under WOT, head temperatures stayed between 335F and 345F. Lower by at least 10F, that's not the biggest change I observed. Also, in traffic, the head temperatures would drop down to 300F and sometimes into the 290s. Before, once the engine got to a particular temperature, it rarely would drop in temperature below 324F in traffic. Apparently, the lower tin most definately helps keep things cool both at lower and higher speeds. 

New Dynomax Muffler

I chose to retire my existing $17 turbo muffler from Autozone for something a little nicer. I bought a Super Turbo (no relation to the above turbo, which was a cherry bomb branded) made by Dynomax. I picked this new muffler up at the local Farm and Fleet for abour $70. The muffler itself weighs probably three times that of the original. Now, rather than the raspy note the exhaust has a more developed and mellow tone to it that comes to life when the pedal is mashed. I coated it with the 2000F thermo-tec paint (some I had left over), so it matches the jet black appearance of the wrapped header.

Reducing engine bay temperatures and improving air distribution, part 2

To further reduce the intake air temperature at the cooling fan and overall in the rear of the vehicle, I also decided to wrap the header with a thermal wrap. Manufactured by Thermo-tec, they claim more HP and up-to 70% reduction in temperature of the exterior of the header, compared to an unwraped/uncoated header. Installation is straightforward except for the fact that you are working with fiberglass and it gives me the hives. They have you wet the wrap, then install it. Afterwards, a 2000F paint goes over the wrap to seal it. Just fire up the engine and watch the smoke billow from the exhaust. The cure process generates tons of smoke - I forgot about that and started the car in the garage. Once it stops smoking, the somewhat flexible wrap turns hard. 

Tuesday, August 15, 2006

Reducing engine bay temperatures and improving air distribution, part 1

Thanks to a very observant Timothy Beradelli (fellow 356 list member and seasoned builder), it was pointed out to me that on cars with european heaters (356's that is), in place of the stale air flapper boxes, there is sheet metal that routes the air past the exhaust ports and further downward. 

In an attempt to simulate these missing pieces of engine tin, I fabricated them myself with aluminum sheet, some aluminum angle stock, and lots of rivets. The engine tin is then held in place with safety wire for easy installation (and removal for further cooling testing).

Thursday, August 03, 2006

More on oil temperature

I took a nice long drive of about 35 mi tonight. The weather had cooled down from the highs in the low 100s (F) to a wonderful 74F. A perfect chance to check my oil temps and actually not cook myself alive in the process. At no point did the oil exceed 180F, so I am very pleased. Head temps floated between 290F and 340F, depending on what I was doing. 

Flapper Boxes

It was pointed out to me by fellow 356 Registry list member Timothy Berardelli that the higher than normal oil temps may be linked to the lack of flapper boxes. He made the comment that they are very important to directing the cooling air and I'm thinking now that they may help in scavenging the exiting hot air out of the general vicinity of the engine. He also mentioned that the factory added the pieces to help balance the cooling betwen cylinders. Makes perfect sense to me. I am going to fabricate some aluminum plates to simulate the flapper boxes, as the stock ones don't fit with Skirmants race header.