How to Reduce Under Hood Temp - Exhaust Wrap
To assist with keeping under hood temperatures down you may want to try wrapping your exhaust. Even though I am running stock cast iron exhaust manifolds on my 454 I was able to utilize Speedway Motors part number 91013804, 1-inch by 50-ft Black Header Wrap. Every little bit helps with keeping your car cool on those hot summer days when cruising. And with the smaller 1" design I was able to wrap the manifolds with sharp bends around the primary tubes fairly easily. Of course, it would be a lot easier to do this with the manifolds off of the car and I highly recommend removing them to wrap them. However, I gave it shot with them still on the vehicle.
Before I started I devised a plan of attack. I started with the first primary tube and wrapped it down to the main collector and past the second primary. For this, I wrapped one complete revolution around the primary tube, then removed the wrap and folded it over itself. Then I could gauge how much wrap I needed by overlapping the folded over portion working my way down the tube without actually wrapping it. That way I wasn't feeding 50-feet of wrap through a small area. Once I cut the length of wrap I needed to start I secured the top of the wrap by the head using Speedway Motors stainless steel exhaust wrap ties, part number 91560014 in 14 inch length. To secure this style of tie you feed the length through the head just like a normal zip tie.
However, the head on these don’t have a clip and the length of the tie is smooth. So you pull it tight onto itself and cut the excess off. I then used a pair of needle-nose pliers to roll the end over on itself up to the head of the tie to secure it tightly and not leave any sharp edges to catch on.
With the first primary tube wrapped I moved to the second and repeated the process until the entire exhaust manifold was covered. This was fairly easy to accomplish with the exhaust manifold still on the car and leaning over the fender. But as I stated earlier it would be a whole lot simpler to wrap the exhaust manifold off the vehicle and re-install.
I did extend the wrap all the way down the downpipe on my exhaust as well utilizing 50-feet of wrap per side. With both sides done I noticed a considerable difference in heat exposure versus the unwrapped manifold. This resulted in dropping my underhood temperatures and keeping my Big Block Chevy running cooler. It also gave my vehicle that old school performance look and covers up a pretty unsightly cast iron manifold.