This weekend Blair Patrick has made a trip up to Minnesota from Tennessee, to dyno a couple of rather interesting engines. One of Blair's customers, Rob (fetorino on our forum), has joined us from California because his engine is one of the ones we are dynoing. The first engine is a 352 stock eliminator engine, and the second is Rob's 496" tunnel port. We got going on this yesterday morning, and Blair was figuring about 350-375 horsepower for the stock eliminator motor, and 650-700 horsepower from the tunnel port.
We started yesterday with the stock eliminator motor. This is a very interesting combination because of the rules. Blair has to run the C4SE cast iron intake manifold that came stock on a '64 Galaxie (where the engine is destined to go), and while the cam can be a cheater cam, it is limited to the stock .408" lift! It also has to run the stock compression ratio (9.4:1 I think), and a very small (450 cfm) Holley carb, or else an Autolite 4100. Blair put quite a bit of duration in the cam to get it to run at the higher engine speeds and try to make the horsepower number. The engine is equipped with CP flat top pistons, Crower rods that meet the NHRA rules, and a stock 352 crank, plus rockers and shaft supports from Precision Oil Pumps. The engine uses a Crane distributor with locked out timing, run by my MSD Digital 6. Blair also brought a set of dyno headers for the engine. Here's a picture of the engine ready to run on the dyno:
I hadn't run anything on my dyno since last August, so it took us longer than anticipated to get the engine hooked up and ready to run, but we finally got the engine running and the cam broken in around 3:00 PM. Blair had fitted the engine with really wimpy break-in springs, around 100 pounds on the seat and 200 over the nose; they were just the inner spring from a fairly strong double spring that he had in stock. They looked pretty funny on the engine when we pulled the valve covers to change them; heres a photo (sorry its kind of dark):
Those are some small diameter springs LOL! They don't look as small in the photo as they do in person, because Blair set this engine up to run with beehive springs from Comp Cams during normal operation, so the retainer is small in diameter. Blair and Rob spent the next couple of hours changing to the normal springs so we could make some dyno pulls. Here's a shot of the beehive springs installed on the engine:
Once we had the springs installed we ran a total of 14 dyno pulls on this engine. We faced a few dyno issues (I had to clean a couple of the water filters) along the way, but other than that, once we got up and running everything seemed to go pretty well. We made 350 horsepower on the second pull, and then messed around with running different RPM ranges and timing to optimize the combination. Here's some data from pull #8, where we were getting the timing dialed in but only running to 6000 RPM:
Looking at this data it didn't appear that the engine was really falling off too much in power, so we decided to run the remaining pulls over the 4500-6500 RPM range (this engine is expected to get a 5000 RPM converter, so data below 4500 RPM is probably not significant). After a little more tuning the best pull netted 363 HP, and this was with 44 degrees of total advance in the locked out distributor! I don't think I've ever run that much timing on an FE before. Here is the data:
According to the A/F numbers on the dyno the engine was running kind of lean (~13.3:1 A/F), so for the last pull on the Holley carb we jetted up a couple of numbers in the primaries and secondaries. The A/F numbers came down quite a bit but we also lost some power, so maybe this engine wants to run on the lean side. This is a good example of how not every engine is the same, and you have to jet for horsepower, not A/F; air/fuel ratio is a guide only.
For the final pull on this engine we threw up a prayer and installed the 4100 Autolite carb. This was a bone stock carb that had been rebuilt, but it had promise because it flowed more air than the Holley carb. Here's a picture of the carb on the engine:
Surprisingly, this thing made 350 horsepower as it was, and it ran really lean, like 14:1 or higher! We think there is probably at least as much power in this carb as there is in the Holley once we get it jetted right. Here is the dyno data:
Today we are going to do the tunnel port engine, so I will post some results on that a little later, probably tomorrow morning. Stay tuned...
