Muscle Mustangs & Fast Fords
RDI Street 392 Crate Motor - Wicked Windsor In A Box, Part 2
This month, we dyno test RDI's Street Pro 392.
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We left last month's story on the RDI 392 Street Pro with the engine ready for the dyno. At this point most project engines are loaded on the dyno, broken in, a few pulls made to verify the output, and that's it. There's nothing wrong with that, but let me remind you RDI's Preston Miller is an ex-Ford Motor Company development engineer with deep ties to Winston Cup. That's a business where remaining competitive means staying on the cutting edge.
A lot of being successful in Winston Cup is knowing how to build a lot of power reliably. With the power levels RDI engines were achieving creeping up and many motors going into road-race cars such as Cobras, Preston wanted to make sure that RDI was totally on top of crankshaft reliability. Consider what a busy drag racer may do in two years is, for a road racer, only equivalent to just a single practice session. This is where we pick up the story of our Street Pro 392 this month.
The dyno facility I elected to use for testing was Kenny Troutman's KT Engine Development in Concord, North Carolina. With more than 15 years of professional experience, Kenny is a dedicated circle track engine builder specializing in Ford-based Busch Grand National motors. His engines have taken championship honors in a number of the top classes and more wins and poles than he can remember. Not only does he build engines specifically for teams, but also runs an engine leasing service. I chose to use this facility not only because of Kenny's outstanding Ford know-how, but also because his dyno has tested a lot of crate motors over the last few years. This puts him in the position of knowing what is good and what is not. This knowledge alone was to prove a valuable indicator as to how effective our RDI unit was.
The break-in procedure (on Valve-o-line mineral oil) was in part a build quality check of the RDI engine. On KT's dyno, oil is run through one of Holley's stainless steel screen micron filters. The advantage of going this route over paper filters is it allows you to see exactly what debris is being expelled from the engine and arrested by the filter. Half of what is arrested by a good paper filter is near invisible to the eye. The better the build quality, the less junk there will be in the filter.
After about an hour of low- to mid-speed cycling of the rpm at various loads and throttle openings, the engine was given a couple of pulls from as low as it would go to about 4,500 rpm. Even before setting up it was very apparent this was a stump puller with a good top end. At this point the Holley filter was opened up and inspected for debris. This proved a lot lower than I normally see. About 95 percent of what was apparent was lint from the parts cleaning paper. The rest looked to be the inevitable iron particles from the timing chain and gear break-in process. So far we were looking good.
Once the engine was broken in, ATI's JC Beattie went to work. JC's function in life, when not driving his oval-track car, is to service the needs of Winston Cup engine builders who require to have a damper specifically tuned to the needs of their race motors bottom-end combination. As RDI's Preston Miller points out, the ATI Super Damper is the overwhelming favorite among WC and BGN engine builders. Having a damper that really cracks down on torsional vibrations not only significantly extends crank life, but also adds power.