Chevy Small Block Part 17 - PT. 17: Fresh Off The Old Block

DM Is Rebuilt and Ready for a New Year

Mike Petralia Feb 1, 2004 0 Comment(s)
Sucp_0402_11_z Chevy_small_block_part_17 Oxygen_sensor 2/12

This EFI system also uses an oxygen sensor (included) that gets plugged into the exhaust. Any muffler shop can weld in the bung that also comes in Holley's kit.

Testing-Year Two
We learned a lesson once again this year. But this time it wasn't because we'd made any mistakes. To the contrary, this time we did everything right. We simply learned that you can't make tons of extra power just by switching from a well-tuned carburetor to fuel injection. There might be a little power there, but don't expect to set any records, that is, unless your carburetor was out of whack to begin with. We were pretty sure of all this already from some of the tests we've tried in the past, but we wanted to give it one last try.

So once again, we removed the carburetor and bolted on Holley's TBI unit, complete with a new progressive throttle body, and new software to control it. What we got was a motor that made good power, but never more power than it did with the carb. This is proof of exactly what we've been saying all along: With EFI you can get better starting, better all-climate running, and maybe even better fuel economy, but you probably won't get better power. That's not to say that EFI is bad. It's actually very good. And once you've gone EFI you'll probably never go back. It's just that EFI is a big jump and may take quite a bit getting used to.

Dyno Testing Part 17
The results shown here are listed chronologically as tests 29 and 30 and represent the power made with the rebuilt short-block using the new Lunati pistons, Sportsman II heads, Lunati hydraulic roller cam, and Holley intake manifold, and we've made comparisons to test 27 and 28, which were done with the old short-block.

Sucp_0402_12_z Chevy_small_block_part_17 Adapter_ring 3/12

We found some extra power when we installed Holley's air cleaner adapter ring. The ring is included in every kit, normally to make sure that any air cleaner will fit on the throttle body. Dyno operator George Vrbancic told us that he'd found power using the ring before and, sure enough, after we dropped it on, power picked up.

Danger Mouse specs for Part 14, Tests 27-28

: 355 cid, 9.4:1 cr, 4.030-bore four-bolt Motown block, 3.48-stroke Lunati crank, 5.7-inch Lunati rods

Test 27: DM Part 14*

GMPP Aluminum Fast Burn heads (62cc chambers, 210cc runners, 2.00-inch hollow stem intake valves, 1.55-inch sodium filled exhaust valves), GMPP single-plane intake manifold, Holley HP750 carb with 73/84 jets, COMP Cams Xtreme Energy hydraulic roller camshaft XR-282-HR (230/236 at .050, 282/288 adv, .510/.520 lift, 110 LS), GMPP 1.5:1 aluminum roller rockers, 36 degrees total advance

Test 28: DM Part 14**

Installed Holley Street Avenger 900-cfm four-barrel electronic throttle body fuel injection.

Danger Mouse specs for Part 17, Tests 29-30:

355 cid, 9.9:1 cr, 4.030-bore four-bolt Motown block, 3.48-stroke Lunati crank, 5.7-inch Lunati rods

Sucp_0402_13_z Chevy_small_block_part_17 Air_tuning 4/12

With the improvement in power that came from the air cleaner ring, we wanted to see if further tweaking the airflow into the throttle body could help build more power. We tried this K&N velocity stack that we stole out of a complete K&N air cleaner kit. It, too, helped build just a little bit more power.

Test 29: DM Part 17*

Freshly rebuilt with World Products Sportsman II angle-plug iron heads (64cc chambers, 200cc runners, 2.02 intake valves, 1.60 exhaust valves), Holley (PN 300-36S) dual-plane intake manifold, Holley HP750 carb, Lunati hydraulic roller camshaft (215/224 at .050, 268/279 adv, .489 lift, 112 LS). COMP Cams 1.6:1 roller rockers, 34 degrees total advance.

Test 30: DM Part 17**

Installed Holley Street Avenger 900-cfm four-barrel electronic throttle body fuel injection.

*Compare Test 27 to Test 29 and note how DM made better mid-range torque with the new package in T29 (T29=412 ft-lb at 3,600 rpm compared to T27=393 ft-lb at 3,600 rpm), but topped out with less peak power than (T29=399 hp to T27=419 hp). That's typical when changing from large runner heads with a big cam to smaller runner heads and a smaller cam.

**Compare Test 28 to Test 30 and again note how DM made much better torque with the new package (T30=405 ft-lb at 4,000 rpm compared to T28=389 ft-lb at 4,000 rpm), but this time DM topped out with more peak power than (T30=394 hp to T28=391 hp). We came into this test hoping to make more power, and we achieved that goal, which shows that with the right combination of parts you can definitely improve the power of a TBI engine.


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