They say nitrous is an engine builders' best friend, and after breaking two pistons on our LT1 Formula's budget 355 on its very first nitrous pass-I couldn't agree more. It is unfortunate that nitrous has such a negative stigma in the community as the result of these types of mishaps, but clearly the fault is not in the nitrous or the maker of the system. It is in the yahoos that purchase and use it. I include myself in the latter bunch, as we attempted to dial back the timing unsuccessfully-a few gallons of VP109 certainly didn't fix the problem. As much as we journalists and editors make it appear that we are above such petty mistakes, occasionally we do in fact screw up. In the process I learned two very important things: I hate OBD I PCMs and plan to get rid of this archaic technology as soon as possible, and even a load-bearing dyno is a poor simulation for the track or street.
Fresh off its transport from...
Fresh off its transport from Intercity Lines, the Formula blasted off a 12.17 at 109 mph on motor at Gainesville Raceway. The fresh Hoosier radial slicks from Summit Racing and Circle D converter had us cutting a 1.63 short time, its best ever! Worried that the weather and the health of the 10-bolt might be a factor, I went right for the juice on the second pass. And unfortunately our tuning issue reared its ugly head again, and for the last time. Nearly as soon as the nitrous hit the motor nosed over, without even the slightest pop or ping-our day was done. Glad we brought the trailer.
Out of a bad situation, though, comes good. Knowing our end goal of 11-second times, which were less than two-tenths away on motor, another stock rebuild would have been sufficient. But I didn't want to take any chances this time, and a forged rotating assembly was in order. Being that a 383 required no more duckets than a 355, that seemed the natural choice for displacement while still at a reasonable price. The extra cubic-inches would also give us the chance of breaking into the 11s on motor with the right weather, using the same heads and cam. Additionally, the cubes would also make the current 226/230 duration roller from Comp even more docile, further enhancing its driveability, and give us the extra torque to make up for the highway-friendly 3.42 rear gears. So in the end, we hoped to have a faster, more reliable and streetable combination than the previous 355 that exceeds our initial goal of an 11-second daily driver. All thanks to the help of Golen Engine Service, one of the most reputable LT1 builders in the country.
After pulling the plug on...
After pulling the plug on cylinder #1 it was apparent that we had catastrophic damage. Clearly something had made impact with the tip and smashed it shut. Cylinder #3 had the opposite problem; something had smashed it open.
While we were waiting for Golen to freshen our Dart heads, machine a new block, and assemble the 383 with the previous Comp Cams valvetrain, we decided it was time we tidied up the new motor's home. If you have been following our LT1 Formula build, then you know that way back in the May '08 issue it received a slick House of Kolor Emerald Green Pearl paintjob from Classic Restoration Enterprises. Unfortunately the stock LT1 was still in place at that time, so it didn't afford the real estate necessary to paint the engine bay. However, after pulling the 355 in the GMHTP shop (with the help of Pete "Jack Knife" Epple), the bay was vacant and ready for some fresh paint. The folks at North Deland Autobody did such a great job on our STi Killer project, they were the natural choice for an afternoon of toxic-fumed fun. With a fresh motor and freshly painted engine bay, the Formula was shaping up to be one fast and clean ride.
Upon closer inspection most...
Upon closer inspection most of the plug tips were a touch white, and clearly had melted aluminum on them. Broken pistons were likely, and the blown-out MAF screen indicated that there was in fact a backfire, though it couldn't be heard.
When I pulled the intake and...
When I pulled the intake and heads off, all was revealed. The head gasket(s) had let go during the explosion, which filled the oil pan with coolant, and the driver side head sustained a bit of damage. The broken material from the pistons had beaten up the combustion chambers on the #1 and 3 cylinders quite a bit. They would need to be cleaned up before reassembly.
The cast pistons broke apart...
The cast pistons broke apart at the edges, all the way down to the ring lands. You could actually see what is left of the top ring through the top of the piston. Amazing carnage. It even cracked both cylinders, turning our block into a giant paperweight. That being said, there was only one thing we could do ...
A call was made to our old...
A call was made to our old friends at Golen Engine Service, so we could build it bigger, stronger, and faster. Golen supplied us with a fresh block, as it does for all of its customers, and Paul machined it to accept a set of 0.030-over pistons, 3.75-inch stroke, 4-bolt mains, and fresh bearings.
Fresh out of the parts washer...
Fresh out of the parts washer the new block was ready for assembly, as you can see it has clearly been baked and blasted. However, Golen will ,of course, hit it with a few coats of black engine enamel (or the color of your choosing) before it leaves the assembly room.
Knowing that the 383-cubic-inch...
Knowing that the 383-cubic-inch mill would be seeing a 150-175hp shot of nitrous, but would ultimately be more of a driver, owner Chad Golen set us up with his Street/Strip package, including Mahle forged, coated pistons with file-fit plasma moly rings and a Scat 4340 forged rotating assembly with ARP fasteners.
A few coats of paint and brass...
A few coats of paint and brass freeze plugs had the block looking spiffy, but the hearty four-bolt mains outfitted with ACL bearings really had my heart aflutter. 383 Mustang-killing-cubic-inches were provided by the 3.75-inch stroke Scat crank and the high-compression Mahle forged pistons were very reassuring, given our past experience with cast pistons. This package goes for a modest $2,999.00 at Golen Engine Service, who also offer some of the best reliability and customer service in the business.