Peaky engine
filed in 67 Mustang
Question: Many performance engine building books and magazines always warn against going too crazy with cams and heads, that after a certain point low end power and driveability will suffer. What is so terrible about driving an engine with a lot of horsepower but only in a small power band? I can see having to shift a lot in order to keep inside the power band. But I don’t see a problem during ‘normal’ driving (when you don’t want to get busy to drive somewhat more aggresive) to sit in the low power range all of the time. Is there something more to it than the above. Are there hesitations, bogings, or any other problems that occur when you drive a race-type car for the street?
My last engine was what you’d call a “Peaky” engine. It was:
a 289, bored .030 over (making it 293), a 288 erson cam (big mistake.), mildly ported heads (port match, bowl blended, 3 angle valve job, otherwise stock), 351W exhaust (port matched to heads), dual 2 5/8 exhaust, edelbrock intake (port matched heads), and a 600 CFM carb.
The engine put out about 210 net horsepower (a guess, but probably pretty accurate), and it ran great from 3000 RPM until 6000 (valve float), in fact, it really pulled right up to valve float, so I probably should have installed stiffer springs to take advantage of it.
Anyhow, my car, a 3160 lb 67 mustang, with an automatic and a 2.73 rear gear didn’t much like the fact that the 289 had practically no bottom end at all.
0-30 was 5 seconds (can you believe that? HORRIBLE!), 30-60 was barely 3 more. Very peaky. It was drivable, but the funny thing is, my 302 4-bbl (stock heads, cam, exhaust) was slightly faster in the quarter mile, because the 289 took so long off the line. A large majority of cars sold in the U.S. come with automatic transmissions. Having a peaky engine with a narrow power band at high rpms makes regular driving very difficult. Just putting the transmission in gear might kill the engine. Stepping on the gas a little can launch you into the car in front of you. For most people in the U.S. with automatics, a broad powerband is the way to go.
Now, if you are drag racing, that’s a different story…
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