I think at some point in time we naively ask the question "What if I installed four intake cams in my M60?" Ya know, 'cause the intake cams have slightly more duration and valve lift then exhaust side. Well, I did just that.....
Using my own Supercharged M60B44:
I mean, why not. This mod could be done for cheap and even for free. All it's going to cost is time, if it nets some more power then totally worth it.
Obviously aftermarket performance cams are the solution, but also prohibitively expensive.
Dyno Sim Results M60B44 with Eaton M112 @ 8psi, OE vs Four Intake Cams
Steps:
1) Remove Coils, Remove Valve Covers, Remove Oil rails from cam caps, Remove Spark Plugs.
2) Spin engine to TDC cyl # 1overlap, cyl # 1 compression. 180° out.
3) Remove accessible cam gear bolts from intake and exhaust
4) Spin engine 360° to TDC cyl # 1 compression, Cyl # 6 overlap. E-A flats on cam facing upwards
5) Remove remaining exhaust cam gear bolts
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Maths:
In stock trim the M60B40 cams are 246°/242°- 9.7mm/9.35mm - 109° ICL/108°LSA
I'll be using the G.A.S. timing blocks, in my previous tests using a degree wheel and dial indicator I found the GAS blocks set the cam timings up for 110°ICL/110°LSA. You'll see me refer to those specs since that's what I'll be using as the baseline. However, in the dyno sim I was able to gain just a bit more by using a 108°ICL/108°LSA, come the time to set cam timing I'll be using the 108°
The theory of phasing the intake cam to be used as the exhaust is rather straight forward. Set the cams up with the timing blocks, both intake cams are at 110° ICL pointing the same direction. Lock down the intake side cams so they spin with the crank. Leave the exhaust side cams stationary so they don't move. Advance the crankshaft 360° + 140°, then lock down the exhaust cams. Now the Exhaust side cam lobes are phased 220° (110°LSA) advanced of the Intake side cam lobes.
This theory would work, if the valves were parallel to the cylinders. However, the valves are angled in the heads.
According to tech literature on the M60B40 the valves are angled 20° for the intake and 19° for the exhaust (+/- 15mins / .25°). Since all the cams spin the same direction and the valves are mirrored of each bank, the intake valves are angled opposite of each other. One banks intake cam has +20° ground into it and the other bank has -20° ground into it.
Source: http://www.e38.org/e32/M60EngineSpecs.pdf
Let's take Bank 1 for example: This intake cam has +20° ground into the cam phasing in order to align with the intake valve lifters, in order to get zero'd out the cam needs to be retard -20°.... Then once it's located in the exhaust position the cam needs to get retard another -19° to align with the exhaust valve/lifters at the correct timings. Bank 2 is the opposite, requiring to advance the cam.
These values are in cam degrees, double them to get crank degrees. 20° intake angle = 40° crank, 19° exhaust angle = 38° crank. This means bank 1's 'new' exhaust cam needs to be installed retard -78° away from it's desired lobe separation angle. Bank 2's 'new' exhaust cam needs to be installed +78° away from it's desired lobe separation angle.
As an experiment, on bank 2 I installed both intake cams set up identically with the G.A.S. timing blocks then set up a dial indicator on the face of the intake lifter for Cyl # 6 (overlap at TDC). Retard the crank for the intake valves to close, then slowly advanced the crank until the intake lift started to move. Noted the crank angle. Did the same for the exhaust side, with the cam phased identical to the intake side. I measured 76° separation of lifter movement in this test. That 2° variance is actually 1° at the cams, and that was enough error tolerance % to abide by the tech literature.
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How does one get crank degrees from an assembled, running engine installed in the car? By counting teeth.
The M60's front mount crank trigger built into the harmonic damper uses a 60-2 pattern, a very common trigger. The missing tooth is offset 60° BTDC. This operating system of the EFI controller uses the trailing edge of the first tooth after the missing section. The TDC mark is also on the trailing edge of the tooth.
Each leading (or trailing) edge of the tooth is exactly 6° away from the one next to it. The tooth is 2.5° wide and the valley between teeth is 3.5° wide. For small crank rotation distances it's easy enough to mark and count the teeth and where on the tooth or the valley the next mark lands to get an accurate idea of how much crank rotation has occurred.
However, to make life easier I encourage removing the harmonic damper from the engine and printing out this degree wheel large enough to place and align the harmonic damper in the middle.
Aligning the 0°/360° with the TDC mark, the trailing edge of the first tooth after 'Missing Tooth' section at 300° and then 180° on the trailing edge of the 30th tooth.
I have also marked on the degree wheel my desired ICL, LSA and subsequent B1/B2 marks. Mark on the damper (I recommend white-out or white paint pen) the angle of the Desired ICL advance, B1 and B2 marks.
If you change the ICL, the LSA timing mark and B1/B2 timing marks will all shift accordingly, don't make changes to one without compensating the other.
After marking the damper, reinstall on the engine.
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9) Remove exhaust cam caps, Remove tensioner bolts, pry tensioner up from oil supply boss to slide exhaust cam gear forward for enough clearance to remove cam cap
10) Remove cam cap studs from journal # 1
11) Lift up, remove and slide exhaust cam back from cam gear to remove exhaust cam completely.
12) Install 2nd intake cams, E 1-4 in Bank 1 and E 5-8 in Bank 2. Install with marked flats facing up, exhaust cam lobes should be phased the same direction as the intake cams at this step.
13) Install all cam caps except #1, keep cam cap # 1 & studs removed for now. Don't install exhaust cam gear bolts
14) Install cam locking blocks on intake side cams, make sure they are flush with heads and bolted down.
15) Loosen intake cam gear bolts; Adjust crank to desired Advance, TDC or Retard for Intake Centerline. Tighten accessible intake cam gear bolts after desired crank angle is set.
16) Remove intake cam blocks, install "intake" blocks on exhaust side camshafts and tighten down flush with head
17) Rotate the crankshaft in standard direction, rotating it 1 full revolution 360° and line up TDC marks
Intake side cams will turn with the engine, exhaust side cams will stay stationary. No valves are hanging open far enough to contact the piston, yet still rotate crank slowly.
18) Install and tighten remaining intake cam gear bolts
19) Advance the crankshaft 62°-68° to align with your first exhaust timing mark, this mark should be for Bank 2 exhaust cam.
20) You may need to remove the exhaust side cam again to allow the cam gear to skip teeth in the chain to align the slots in the gear with the bolt holes in the cam.
21) Once bolt holes are aligned with slots in the gear, reinstall the cam journal 1 studs and cap. Then install and tighten the accessible cam gear bolts. Remove the cam timing block from Bank 2.
22) Advance the crankshaft another 156° to align your 2nd Exhaust cam timing mark on the damper, for Bank 1.
23)You may need to remove the exhaust side cam again to allow the cam gear to skip teeth in the chain to align the slots in the gear with the bolt holes in the cam.
24) Once bolt holes are aligned with slots in the gear, reinstall the cam journal 1 studs and cap. Then install and tighten the accessible cam gear bolts. Remove the cam timing block from Bank 1.
25) Spin the engine over by hand, slowly, reinstalling and tightening cam gear bolts as they rotate over the timing cover.
26) As you are spinning the engine over by hand pay attention to the exhaust lobes and intake lobes as cylinder # 1 in Bank 1 reaches overlap, visually make sure the intake opens just as the exhaust is closing. Do the same for cylinder # 6 in Bank 2
27) Reinstall oil rails, valve covers with new gaskets, spark plugs & coils.
Congratulations you now have four intake cams.
Fire it up....
My initial thoughts and impressions: It changed the exhaust note, in a good way. Sounds beefier. There is a noticeable amount of torque and tip-in response increase. Mid range feels similar. Pulls strong through the entire RPM range.
There is not a dyno near me, so no before and after numbers. But I do like to use the Auto-Tune feature in Tunerstudio on the standalone EFI controller to gauge if a mod has helped or hindered. If Auto-tune adds fuel at any given RPM vs MAP cells in order to maintain tuned AFR's then clearly more airflow is going through the engine in that range and more power is being made. If Auto-Tune removes fuel to maintain AFR's then less airflow is moving through the engine and subsequent power loss.
On the test drive Auto-Tune added significant fuel in the low RPM cruise and acceleration cells. Added some fuel in the mid-range and even more fuel in the top end. I'd say that's a win, and it does feel good on the street. Thanks for checking out my project - Mykk
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