Small-Block Bolt On Tests - Chevys Gone Wild, Part 2

Our once-meager junkyard mouse has turned into a real rat-eater with simple bolt ons.

Richard Holdener Oct 13, 2006 0 Comment(s)
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Without changing any component on the short-block, we were able toproduce 200 hp, 300 hp, 400 hp and even exceed 500 hp using the rightcombination of bolt-on performance products.

In Part 1 of Chevys Gone Wild last month, our 355 small-block startedout stock from the bone yard and worked its way into finally becoming aperformance motor you wouldn't mind sticking in your Camaro or Chevelle.In stock trim, the build up featured a two-barrel induction system (withattending air cleaner), a set of stock 882 heads, stock hydraulicflat-tappet cam and a rebuilt short block (with forged pistons fromProbe Racing).

Though every Component was freshened up to as-new condition, the resultswere somewhat predictable given the factory cam, heads, and two-barrelinduction system. Running through the stock exhaust manifolds, thetwo-barrel small-block pumped out 229 hp and 350 lbs-ft of torque on anengine dyno. After running through a barrage of bolt-ons, we wereeventually rewarded with peak power numbers of 364 hp and 422 lbs-ft oftorque. The list of modifications included an air filter upgrade,long-tube headers and a factory Q-Jet carb and intake. Next came aWeiand 8004 intake, a set of ported 882 heads from Power Heads and amild (emissions legal) Pure Energy 246 cam from Comp Cams. We finishedoff the small-block with the installation of an Edelbrock Performer RPMAir Gap intake and 650 cfm Speed Demon carburetor. It was this newinduction system that brought the power numbers up to 364 hp and 422lbs-ft of torque.

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The four-bolt block was stuffed with a cast crank with forged rods andpistons courtesy of Coast High Performance.

While we are currently spoiled by the factory 400-hp LS2 and 505-hp LS7motors, there was a time when only the mightiest of small-blocks managedto produce 375 gross hp. What was really satisfying about the project sofar was the torque production, which not only peaked at 422 lbs-ft, but(more importantly) exceeded 400 lbs-ft from 2,900 rpm to 4,700 rpm. Evendown as low as 2,500 rpm, the motor produced 390 lbs-ft, meaning thatthe drive-ability and throttle response offered by this mild combinationwould be impressive. Needless to say, we were more than satisfied withthe power gains offered by such minor and cost-effective changes. Theported (stock) cylinder heads offered by Power Heads were far fromexotic. The 882 castings were hardly what you would consider desirable.These castings are available from just about any wrecking yard or headshop.

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Last month we finished up with our 355 by adding an Edebrock PerformerRPM Air Gap intake and Barry Grant Mighty Demon carb to the ported 882heads and Pure Energy cam. That combination produced 365 hp and 422lbs-ft of torque.

Actually, similar results can be had from just about any small-valve(1.94/1.50), big chamber (76cc), cast iron factory cylinder head. PowerHeads purposely didn't go hog wild on the porting, instead concentratingon minor bowl work and some gasket matching. Part of the porting packageincluded the installation of larger 2.02/1.6 valves, but it might havebeen interesting to see what happened with just the porting. The powergains offered by the simple addition of a stock four-barrel intake andQ-Jet carb were equally impressive, as the four-barrel offered as muchas 30 hp.

It's interesting to note that the peak power always occurred near 4,500rpm, whether the engine was equipped with the two-barrel, four-barrel,or Weiand 8004 intake. Naturally this changed after adding the PE246 camand ported heads.

After seeing the gains offered by such simple bolt-ons in Part 1, wewere excited about beginning round two. The test mill, built by CoastHigh Performance, was ready for more abuse, so off came the ported stockheads and mild Pure Energy 246 cam and on went a set of aftermarketaluminum heads and healthier bumpstick. You will remember that thecombination of the ported stock 882 heads and PE246 cam netted us a cool53 hp (peak to peak). Would the new Holley SysteMax aluminum heads andslightly wilder (though plenty streetable) XE268H cam offer similarresults?