Engine Stock engine top half options for HP

Mustang5L5 said:

I never understood why people said to turn on the heat when doing a flush when it makes no difference to the actual flow through the core

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Most likely a holdover from when cars had heater valves that did control the flow thru the heater core.

MrPerfect2 said:

on a 91 GT convertible auto with 327 gears - “ IF “ I needed ( or wanted ,lol ) the top half engine rebuilt ( I know the term rebuilt is vague ) say a head gasket failed and needed to put a lot of labor hours in it . AND , I wanted to stay some what stock but get some extra HP power and torque from the effort . Does this sound like the way to go if head gasket change needed : retain the original iron heads ( more durable to resist warping ) have machine shop port them , change valves , guides , springs and add 1.7 rockers & port match the lower intake , then add some equal length shorties . Would this add some power ? Would stock throttle body , injectors and upper plenum be sufficient ?

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Honestly if it were me I’d do head studs with gt40 heads and a decent cam and that will gain a decent amount for u

While this might be an apples to oranges (carburated ’83 vs. more modern ’91) comparison, I thought you might like to know how a new top end (CAM, intake, heads) worked for me. With help from this forum, I guestimate the top end added 75-80HP (at wheels) and many smiles.

*Edelbrock Heads: Performer RPM, non-emissions SBF 60229 with 60cc chamber volume. 9.3:1 CR.

*CompCams valve train: XTREME Energy (35-238-3 XE262H) camshaft, Magnum (1442-16) 1.6:1 roller tipped rocker arms, hydraulic lifter set (832-16), Magnum (7632-16) 6.800” hardened push rods, double roller steel gear timing set (2120).

*Air/fuel system: Edelbrock Intake manifold (7121) Performer RPM, Edelbrock (1905) AVS2 650CFM carburetor.

At today’s prices the above might cost you $2500-$3000 if you shop at Summit Racing. 10 years ago, I spent less but my wife never fails to let me know it cost much more than I originally thought. Additionally, some other facts about my build:

*Bottom end: Stock block and crank. Bored 20 mils over, polished crank. Rotating assembly (crank, flywheel, damper) dynamically balanced for new pistons, rings, rods, etc.

*Exhaust: MAC exhaust with 1.5” shortie equal length headers, X-pipes, Flowpath mufflers and 2.5” dual exhaust (This MAC exhaust helps the smile factor).

This car was rated at 175BHP new with single exhaust. Probably 275-280 BHP now. I still have a tall 308 gear in the 7.5” back end but this car is still a blast when winding 1st, 2nd, 3rd up to 6000 RPM. I take it easy on take off and shifts to preserve my 225k mile T5. A 373 would be a blast and a bit easier on the old T5.