When we built Danger Mouse (DM) a couple years ago, the plan was simple. Build an engine that we could abuse again and again and at every possible power level. Our plan included testing some of the smartest combinations you guys, the readers, could come up with. And the letters started pouring in. DM has been the first and only magazine engine ever built specifically to test the reader's ideas. And there's no stopping it now. We have stopped doing one thing with it however; counting dyno pulls after we reached 1,500 (not all of which have been recorded). And in the term we have seen lots of both good and bad results. In fact, we've tried so many different combinations by now that we think we've found a few new recipes for perfection. If you'd like to make 500-plus hp with your pump gas 355, we've got that covered. Or how about making over 700 blown horsepower on pump-gas little motor? Danger Mouse can show you how. This time, we've shot deeper into the realms of supercharging, roller cams, and EFI technology using DM as or bullet. And best of all the results we got are right in here.
If you're unaware of DM's history, here's the low-down. We built DM with the intention of running it ragged on the dyno every month trying to make all combinations work the best they could. So, to reach that goal, DM was built tough. Starting with a World Products 4-bolt Motown block bored .030-over we dropped in a complete Lunati rotating assembly making it displace a street-real 355 cid. We even left the flattop 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 components on top 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, DM made an outstanding 308 hp and 395 ft-lb of torque in totally stock trim (see BASELINE: Test 1). Then we spent the rest of the first year testing different top end combinations, while we left the bottom end completely untouched. This month's story is a recap of the best tests beginning in 2004, (we've already recapped everything up until that point in SC May and December, 2003). It's most interesting to note that, since the beginning, we've been able to increase DM's normally aspirated power output by a factor of 200 hp and by adding a blower we've almost doubled that increase to over 400 extra ponies.
DANGER MOUSE STOCK BASELINE (TEST 1):
Bore: 4.030 x Stroke: 3.76, 355cid
Heads: stock 461 "Camel Hump" castings
Cam: COMP Cams 246PE hydraulic (246/263 adv duration, 203/212 duration @ .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
Test 1: 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. Since then, we feel we've created perfection in several categories; one of which has been EFI. Back in DM Part 11, (August 2003) we tested some of the more high-end EFI components using a F.A.S.T. multi-port system. This time around we wanted to test a more simple conversion. So we gathered up a Holley Street Avenger Throttle Body Injection (TBI) system and bolted it on to see what it could do. The results were not outstanding. And after several days spent tuning on the dyno, we could barely get the TBI to make as much power as a Holley HP carburetor did. Those results did not surprise us, however, there were still some marked benefits from the TBI system. Including better starting, better all-climate running, and maybe even better fuel economy, but we didn't get better power, although there was a slight power gain at 2,500 rpm.
DM Part 17--Test 29:
Freshly rebuilt with World Products Sportsman II angle-plug iron heads (64cc chambers, 200cc runners, 2.02 intake valves, 1.60 exhaust valves), 10:1cr, Holley PN 300-36S dual-plane intake manifold, Holley HP750 carb, Lunati hydraulic roller camshaft (215/224 @ .050, 268/279 adv, .489 lift, 112 LS). COMP Cams 1.6:1 roller rockers, 34 degrees total advance.
DM Part 17--Test 30:
Installed Holley Street Avenger 900cfm 4bbl electronic throttle body fuel injection.
Immediately following our less than exciting TBI test, we jumped overboard! A call was made to ATI/Procharger and we got our hands on one of their D-1SC centrifugal superchargers, which definitely gave us the "most power on pump gas".
For DM Part 18 T31 & T32 the blower required a few different components to make sure the engine would live and make some serious power. To that extent Speed-O-Motive dove back into DM's storage locker and pulled out the old set of Trick Flow Specialties (TFS) aluminum heads we've used several times in the past. Not only do the TFS heads make great power, their big combustion chambers also lowered DM's compression, which is exactly what was needed for the blower. Speed-O also installed the biggest cam we had run up until that point, a Crane Cams hydraulic roller with plenty of lift and duration to make the power we were looking for. And then they topped it off with an ACCEL GEN VII DFI fuel injection system to give it the utmost in tunability. At the time, Speed-O had not finished their engine dyno cell yet, so we trucked the engine back to Vrbancic Brother's Racing and once-again bolted it onto their DTS engine dyno for a days worth of blowin' in some power!
In order for the boosted power increase we got to mean anything to you, we first left the blower belt and induction plumbing off so we could test it without any boost (see T31). Then we hooked the blower up and spent the rest of the day searching for power. And boy did we get some! Max 697 hp and 613 ft-lb of torque, all on pump gas (see T32). But, there was a problem, which we only found when we tore the motor back down after the tests. The Fel-Pro PN1003 head gaskets we used were never meant to hold back the kind of boost we were running (almost 15 psi) and they literally began to push themselves right out of the engine (see photos). If we were to do this again, we'd simply install a set of new Multi-Layer-Steel (MLS) head gaskets that can hold back much more pressure.
DM Part 18--Test 31:
355 cid, 9.1:1 cr, 4.030-bore 4-bolt Motown block, 3.48-stroke Lunati crank, 5.7-inch Lunati steel rods, TFS aluminum heads (Summit Racing PN TFS-30400013-CNC, 72cc chambers, 195cc runners, 2.02/1.60 valves). Accel Gen VII DFI with 55 lb-hr injectors and Dual Sync Accel computerized distributor. Crane Cams hydraulic roller camshaft (PN 119681, 306 intake / 314 exhaust advertised duration; 240/248 @ .050; .595/.595 lift, 114 lobe separation). Crane retrofit hydraulic roller lifters, Crane pushrods, and COMP Cams 1.6:1 rockers.
DM Part 18--Test 32:
Installed Procharger D-1SC centrifugal supercharger with 4.25-inch pulley.
OLD FASHIONED POWER
Right after the blower test we moved back to making power the old-fashioned way, on the motor. We had been wanting to try out Edelbrock's Victor Jr. heads and intake manifold for quite a while by now, but were hesitant because DM might not be capable of using that much air. But, we felt that maybe if we ordered the smaller combustion chamber heads and equipped DM with one of COMP Cams' newest Xtreme Energy Street Roller camshafts and the latest, mightily-efficient Demon carburetor, we just might be able to squeeze off 500 ponies! So we asked the guys at Speed-O-Motive to install the new components and strap it onto their new DTS dyno.
The results were spectacular! A true 500hp street bruiser that looked and sounded every bit the part (DM Part 19--T34). Also, just for giggles, we were curious what difference running hydraulic roller lifters on this new solid roller cam would make and we learned quite a bit from that test alone. Specifically, that in this case, running hydraulic roller lifters on solid roller cams really doesn't make much of a difference. We gained some mid-range power running the solid rollers, but lost it all back around the top end, probably because the hydraulic roller lifters actually made the cam act "bigger" since they run at zero lash, so average power was a wash. We do feel however, that if the cam we'd used had been just a bit larger, the HR lifters wouldn't have kept up so well. That's because bigger cams make more power at higher rpms and that's where HR lifters can begin to suffer. You really need to fine-tune the valve train to make a HR spin that high. As it was, we had no trouble revving to 6,600 rpm with the HR lifters. But the motor was like a switch at that point and it practically turned off if we tried to push it above 6,600. Ironically, the power curve was all finished by then anyways, so more rpm was a moot point. And it still didn't rev any higher after we installed the SR lifters either!
DM Part 20--T35 was all about sealing. We've known Total Seals' gapless top rings have been out for quite a while now, but hadn't seen anyone using them in a true street engine yet. Well, we wanted to try and the results were outstanding, especially considering that the gapless rings only cost about $100 more than standard set we replaced. More power and torque was made at almost all points, except at the very top end of the curve, which surprised us. A call to Total Seal after the test explained the problem. "You coulda' done better," they told us. "If you had increased the high-speed air bleeds in your carb, leaning out the top end of the fuel curve, you wouldn't have lost the power up there. Our testing has shown gapless rings pull more vacuum at higher rpm and therefore will also pull more fuel causing the engine to run rich at the top end." A review of DM's fuel curve confirmed this to some extent, but we didn't see a huge difference in the Lambda Air/Fuel readings from low to high rpm, so we never thought to change the air bleeds. Also, Total Seal recommended running less ignition advance with gapless rings, because they claim peak cylinder pressure comes just a bit sooner and therefore the combustion process begins that much quicker. Unfortunately, the engine was off the dyno before we could test either of these theories. But, we trust the information from Total Seal and have no reason to doubt its validity.
DM Part 19--Test 34:
355 cid, 10:1 cr, 4.030-bore 4-bolt Motown block, 3.48-stroke Lunati crank, 5.7-inch Lunati rods, Edelbrock Victor Jr. heads (64cc chambers, 215cc runners, 2.08" intake valves, 1.60" exhaust valves), Victor Jr. intake, Mighty Demon 650 carb, COMP Cams XR280R solid roller camshaft (242/248 @ .050, 280/286 adv, .600/.606 lift w/ COMP 1.6:1 rockers, 110 LS), COMP solid roller lifters lashed at 0.016-intake and 0.018-exhaust, 38 degrees total ignition advance.
THE BIGGEST AND BADDEST YET
Once the Total Seal rings gave us extra power, we began believing that more could truly be better in this case. So, after a lengthy phone call spent convincing Edelbrock to let us try their big, Super Victor racing manifold with an even larger COMP Cams solid roller, we went back to Speed-O-Motive's dyno to see if we could break the 550hp barrier. Well...we didn't lose any power and DM certainly made more power than it did the month before, but the results were a far cry from spectacular this time. After swapping the cam, intake, and carburetor, we only saw a 13hp increase and 14 ft-lb of extra torque (see: DM Part 21--T35 vs. T36. While some racers would jump for joy at such an increase, and we're certainly not putting it down, for the time, effort, and expense of the swap the results were not worth it in our minds. All that means is that we've pretty much hit the wall with the current parts combination we have and just like on the street, throwing bigger parts at it won't make it go any faster. So we're rethinking our strategy and planning some cool stuff in the near future. We're confident we'll see close to 600 hp by the end of this year, still on pump gas, too. But while we're not totally sure we can get there from here, one thing we are sure of is it won't be easy, but it'll sure be fun!
DM Part 21--Test 36:
Same as T35 except swapped Edelbrock Super Victor manifold and COMP Cams XR286R solid roller camshaft (248/254 @ .050, 286/292 adv, .606/.612 lift w/ COMP 1.6:1 rockers, 110 LS), Holley HP1000 carb, 38 degrees total ignition advance.
DM Part 20--Test 35:
Same as T34, but with Total Seal ductile iron Gapless top rings (PN M3690 35)