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Horsepower! - 235hp Ford Inline Six

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203ci, 235hp Ford Inline Six

Jim Grubbs Motorsports, Valencia, CA

Last month, we gave you an over-the-top turbocharged Hemi, so this month we thought we’d try something a little tamer. Owners of inline engines often feel they never get any love, so when we ran across this tiny Ford inline six, we had to stop and take notice. Jim Grubbs Motorsports (JGM) built the engine for customer Tory Singer. These small sixes originally came in early ’60s Falcons, Mustangs, and Fairlanes, displacing barely 200 ci. That isn’t even the smallest of the family—that distinction belongs to the 140ci version. The key feature on this engine is the aluminum cylinder head available from Classic Inlines, a Mesa, Arizona, company that specializes in Ford inline six engine components and development. While 235 hp doesn’t sound like much, keep in mind that this engine is displacement-challenged and only spins to 6,200 rpm. Even by expanding the inches per cylinder into a V8, it would still only push 270 inches. Dividing 235 ci by 203 hp means that little scrapper is making 1.16 hp per cubic inch. Equate that to a 500ci big-block, and you’d have 580 hp. Atypical engines are becoming more and more popular, as the LS and small-block Chevy stigma continue the controversy over boring engines. As in this case, it’s not always about the horsepower. Sometimes, six is just more fun than eight.

[1] What you can’t see on the other side of the Ford inline six engine is an electronic ignition distributor from DUI that supplies the spark timing at 35 degrees BTDC to make this power.

[2] Classic Inlines says the reason it chose not to build a cross-flow head with the intake on the opposite side of the exhaust was due to both packaging and replacement-part issues. The company worked mainly on improving combustion efficiency with a revised combustion chamber and improved ports. The heads feature larger 1.84/1.50- inch valves in a much improved quench design. The valve cover is also a Classic Inlines piece.

[3] Troy and JGM agreed that using Classic Inlines’ aluminum intake was a good idea. The aluminum single-plane intake mounts a small, standard-flange Holley, as shown here. Singer used a 390-cfm four-barrel carb with a vacuum secondary. Below the intake is a set of 15⁄8-inch headers also from Classic Inlines.

[4] JGM punched this little Ford out to 3.71 inches while the stroke remained the same, at 3.125 inches. Grubbs also added a Clay Smith hydraulic flat-tappet cam with 221/221 duration at 0.050 with a 108-degree lobe-separation angle and Yella Terra roller rockers. Compression ended up just less than 10:1 using Speed-Pro pistons and Sealed Power rings.

Dyno Numbers

We arrived just in time to watch the JGM guys pull the handle on this little six and record the numbers. If you plot the torque curve, it’s nearly pool-table flat, which makes this a great street engine.

RPM TQ HP
4,000 225 171
4,200 228 182
4,400 227 190
4,600 225 197
4,800 227 208
5,000 227 216
5,200 225 223
5,400 223 229
5,600 219 233
5,800 211 233
6,000 200 229
6,200 199 235

More Info/Classic Inlines; 602/708-6650;ClassicInlines.com

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