When we built Danger Mouse (DM) more than a year ago, the plan was simple. We wanted to have an engine in our stable that we could use to test and re-test every possible power combination we could think of. Our plan also included testing any of the smart combinations you guys could come up with as well, and the letters started pouring in. DM was the going to be the first magazine engine built specifically to test readers' ideas. Well, after more than 1,000 dyno pulls, (not all of which were recorded), with both high and low results, we've tried so many powerful combinations that we think we've found a few new recipes for perfection. If you'd like to make 480-plus hp with your stock 355-cid short-block, we've got that covered. Or how about making over 600 hp on pump gas from the same 355-cid and not sacrificing next year's vacation to do it? Danger Mouse can show you how. We've even covered the newest EFI technology too. And best of all. it's right in here.
For a quick recap since DM's inception, here's the low-down. We built DM with the intention of running it ragged on the dyno trying to make every combination work the best way possible. So, to reach that goal, DM had to be tough to take the abuse we planned to dish out. Starting with a World Products four-bolt Motown block, we bored it .030-over and dropped in a complete Lunati rotating assembly making it displace 355 cid. We even left the flat-top Lunati pistons 0.040-inch down the bore (as opposed to a true "zero-deck") to more closely approximate what you might have under your hood. Then we bolted some rather boring stock GM iron components to the top of it and slapped it on the dyno for its first run. After that day was finished, we were happy to report that with just a few tuning tweaks to dial it in, DM made an outstanding 308 hp and 395 ft-lb of torque in totally stock trim (see Test 1). Then we spent the rest of the year testing different top end combinations, while we left the bottom end completely untouched, to see how much power we could make and what helped us get there the easiest. This month's story is a recap of the best tests from the latter-half of 2003, (we've already recapped the first half in the May 2003 issue) plus what we think is the best overall combination we came up for your money.
THE BEST BUILD
Through all this we've learned that there are certain ways to build an engine to give you the best power-per-dollar. And the best thing is that all the combinations we've tried so far would be easy for you to duplicate yourself. Perhaps the best combination for the money we've tested has to be the Vortec iron heads and COMP Cams XE262 camshaft with an Edelbrock Performer RPM Air Gap intake we ran in DM Part 6 (February 2003). This engine made tons of low-end torque and still managed over 415 hp--and all from a very affordable and streetable package that even makes enough vacuum for power brakes.
T15--DM Part 6: GM Vortec iron heads SDPC PN SD8060A (64cc chambers, 170cc intake runner volume, 1.94/1.50 valves) with Comp Cams 1.6:1 Magnum roller tip rockers PN 1418-16, Edelbrock Performer RPM Air Gap Vortec intake manifold PN 7516 COMP Cams XE262H cam (262/270 advance duration, 218/224 duration at .050, .462/.469 valve lift, 110 lobe separation) straight up.
DANGER MOUSE STOCK BASELINE (TEST 1):
Bore: 4.030 x Stroke: 3.76, 355 cid Compression: 9.4:1 Heads: stock 461 "Camel Hump" castings Cam: COMP Cams 246PE hydraulic (246/263 advance duration, 203/212 duration at .050, .429/.438 valve lift, 110 lobe separation) Intake: Stock cast iron Carb: Carb Shop Q-Jet Ignition: Proform HEI, Champion No.14 plugs Fuel: 76 Performance pump gas, 91 octane Ignition Advance: 37 degrees Exhaust: 1 5/8-inch Hooker headers into 3-Flowmaster mufflers
T1: Represents what a typical 355-cid small-block might make if it had just been blueprinted, but still had most of its stock components.
After the baseline had been established, we began our long quest to build the most power possible using nothing but off the shelf parts. We created perfection in several categories; one of which was supercharged with what we like to think of as the "most power on pump gas". In order to meet the pump gas challenge we had set forth for ourselves, we opted to install a small (177ci) Roots-style Weiand supercharger. This little two-lobe blower sits on top of a cast-aluminum Weiand intake manifold and pumps more air into the engine than it could normally breath in giving it the power-producing capacity of a much larger displacement engine. In other words, it kinda turns a 350 into a 502. But, installing a blower is not a task one should take lightly. It's a serious jump in performance and there are several key precautions one must take to ensure your blown engine doesn't blow. Beginning with T19 we installed a set of aluminum Trick Flow Specialties (TFS) cylinder heads to lower DM's compression to a more blower-friendly 8.5:1. The new heads also gave us some extra airflow flow capacity with their big intake ports. We baselined the engine with the TFS heads, an Edelbrock Performer RPM Air Gap manifold and Demon carb, and a COMP Cams hydraulic blower camshaft to see how it would compare blown to unblown.
Here are the unblown specs for DM. T19: TFS aluminum heads (Summit Racing PN TFS-30400013-CNC, 72cc chambers, 195cc runners, 2.02/1.60 valves), TFS pushrods (Summit PN TFS-21407850), Edelbrock RPM Air-Gap manifold, COMP Cams NX274H camshaft (274/292 advance duration, 230/244 duration at .050, .487/.501 lift, 113 LS) straight up. COMP Cams 1.6:1 Pro Magnum roller rockers. The lower compression and large camshaft didn't seem to hurt DM that much. In fact, it had some serious top end pull with 444 hp at 6,100 rpm. Low-end torque fell off, but we expected that since we were running a pretty big cam combined with very low compression. But once we added the blower and made a few tuning tricks, DM came alive with over 600 hp! All 600 ponies were made on 100-octane unleaded pump gas from 76 Racing.
Here are the specs from the best supercharged test for DM. T20: Weiand 177ci mini-blower with 3.07-inch top pulley and 7-inch bottom pulley (228-percent overdrive). Peak 10.3-psi boost at 6,500 rpm, 36 degrees total advance, Holley 950HP supercharger carb, 100-octane unleaded 76 Racing pump gas and NOS octane booster.
Right after the blower tests were completed, we moved onto fuel injection. We learned that Edelbrock was making a new EFI manifold based on its outstanding Victor E casting and thought this would be a perfect match for the new F.A.S.T. EFI system we wanted to try out, but we had to know how much power the engine would make with a carb first. So to get those results, we equipped DM with a prototype COMP Cams EFI hydraulic roller camshaft and a Speed Demon 750 carb sitting on top of the new Edelbrock Victor EFI manifold with corks plugging the fuel injector bosses.
T21: same TFS aluminum heads, Edelbrock Victor EFI manifold (PN 29785), COMP Cams Xtreme Energy EFI prototype hydraulic roller camshaft (281/288 advance duration, 230/236 duration at .050, .544/.555 lift with 1.6 rockers, 113 LS) straight up. COMP Cams 1.6:1 Pro Magnum roller rockers, Speed Demon 750 carb, 36 degrees total advance.
When compared to previous normally aspirated T19, DM's horsepower went through the roof with the new components in T21! Peak power jumped by 30 hp to an outstanding 474 hp at 6,100 rpm but torque fell off down low, so the extra power wasn't a freebie. COMP Cams attributes this to the more-aggressive low-lift ramp profile on the NX274 flat-tappet hydraulic camshaft. The hydraulic roller cam really begins to take over at higher rpms due to its reduced frictional losses. Now it was time to test the EFI set-up.
T22: Installed F.A.S.T. EFI system with Accufab throttle body and 30 lb-hr injectors at 50 psi. Right away the EFI proved its superiority by adding torque down low and increasing power up top. Although power dropped slightly in the mid-range, which we think we could've got back with more tuning time. We also thought DM might have been a little starved for fuel with small the 30 lb-hr injectors we had originally installed, so we switched them to larger 36 lb-hr injectors and got just a little more top end power, but low end went back down, so we put the 30 pound injectors back in.
T23: Switched to 36 lb-hr injectors at 50 psi.
A month went by after the EFI tests and we were a little pressed for time before the next test was due. In a rush to meet the deadline, we hooked DM back onto Westech's dyno and started swapping rocker arms to see if there would be any extra power there. However, the first thing we were greeted with was a loss almost 30 hp and 20 ft-lb of torque (compare T22 and T24)! We still have no idea how or why this happened, but it only got worse from there.
T24: TFS aluminum heads, Edelbrock Victor EFI manifold (PN 29785), F.A.S.T. EFI system with Accufab throttle body and 30 lb-hr injectors at 50 psi COMP Cams Xtreme Energy EFI prototype hydraulic roller camshaft (281/288 advance duration, 230/236 duration at .050, .544/.555 lift with 1.6 rockers, 113 LS) straight up. COMP Cams 1.6:1 Pro Magnum roller rockers, 36 degrees total advance.
T24 was actually supposed to be just a back-up test to confirm the previous month's results just like we did at the start of every month so nothing was changed at all. Only this time the power fell off, and no one knows why. Since we were already on the dyno, we figured we'd continue with our planned day's tests and swap some rocker arms anyways.
T25: Swapped COMP Cams 1.5:1 Pro Magnum roller rockers on exhaust only.
For T25 we pulled an old-fashioned hot rodder's trick that sometimes works today. We left the intake rockers alone and swapped a lower ratio set of exhaust rockers on. That allowed DM to breath just a little more air into its cylinders and helped to make a little more power because of it.
FAST BURN DREAMS
When we first tested DM using the GM Performance Parts cast-iron Vortec cylinder heads the results were outstanding. Then we thought about running GM's Fast Burn aluminum heads, which were based on the Vortec castings, but with some radical changes. For one, the Fast Burn heads have a much larger 210cc intake runner, which, in hindsight, might have been just a bit too much for the little Mouse. Second, we tried a new COMP Cams Xtreme Energy hydraulic roller camshaft that also may have been too big for our needs. In the end, the Fast Burn heads worked well, but power was down when compared to the other set of aluminum heads we'd ran before, which had smaller 195cc chambers. We think this really points out the importance of properly matching components to your application. And that going too big is still not the best way to make power today.
T26: GMPP Aluminum Fast Burn heads (9.2:1 cr, 62cc chambers, 210cc runners, 2.00-inch hollow stem intake valves, 1.55-inch Sodium filled exhaust valves), GMPP single-plane intake manifold, Speed Demon 750 carb, 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.
Our last set of tests for DM included swapping out the 750-cfm carb for a Holley Street Avenger TBI system we had lying around our office. This test did not go too well and we were plagued with failure almost from the start. The engine wouldn't make anywhere near the power it had been making before (compare T26 and T27), and it turned out that our Holley parts had sat in our offices for way too long before we tested them because we learned too late that Holley had updated them since. Our EFI fuel map was wrong for the throttle body we were trying to run so we had a tuning nightmare all day long and when we finally got DM to run, it was almost too late. Since these last tests were such a bust, we've decided to rebuild DM and equip it with the newest Holley components and a smaller set of cylinder heads to make sure it'll run correctly next time out.
T27: GMPP Aluminum Fast Burn heads (9.2:1 cr, 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. T28: Installed Holley Commander 900-cfm four-bbl electronic throttle body fuel injection.
REBUILD, REPAIR, AND RE-TEST
We've learned that no matter how tough you build an engine, there comes a time when it will need to rest. Now is DM's time to rest, while we rebuild it to make it stronger and faster. We've got many more tests and ideas in store, but want to really encourage you to send in your ideas. Send us you wildest fantasy engine build! Or maybe some combination your friend has been running that you can't figure out how it makes as much power as it does. Any idea you have is worth listening to. Of course, we can't run them all and even the ones we do run might be modified a bit to make work within our time and budget constraints. But the bottom line is that DM will live again and continue to be a better way for you to learn how to make the most bang for your bucks.