Faqs

 

Why test with a Single instead of a Multi-cylinder?

  • Convenient sensor access, no neighbor cylinders or valve trains in the way
  • Faster calibration and better, faster data:
    • A/F, EGR, spark timing, start/end of injection, etc. dialed in for the one cylinder being tested
    • Faster mapping, one cylinder not x number
    • Valve timing the same for that one cylinder being tested
    • Small changes show directions and don’t get washed out in vague noise
    • Tighter control of water and oil temps on that cylinder
  • Cheaper/faster parameter testing:
    • One chamber’s shape, piston dome, injector location, cam lobes, valve seats to modify vs. 4 to 8!
    • Deck height and bore offset changes on multi-cylinder very expensive, with a single it takes just minutes
    • Fuel and facility costs for single development much cheaper

When is a multi-cylinder engine better for testing?

Any time other cylinders get involved:

  • Exhaust and intake manifold development
  • Crankcase breathing development
  • Cooling / oiling / structure / system optimization
  • Crank bearing friction studies

Why not convert a stock production engine into a single?

Up side… cheaper
Down side…

  • Need to build:
    • Rotating mass clamps on unused journals
    • Hollow piston like mass on another cylinder for first order balance
  • Better sensor access than multi-cylinder but still restrictive
  • Typical stock block doesn’t have (or have room for) a replaceable wet liner; scratch a bore… have a significant issue
  • Expensive headache to change deck height, even worse to change bore offset
  • Not flexible, stuck with that model. Makes bore/stroke/head/rod-length changes issues
  • First order force balance only, so:
    • Adds noise to force sensitive cylinder-pressure sensors and their high impedance driven cables. Also fuel flow data is worse with vibrating fuel lines.
    • Expensive sensors and all cabling doesn’t last as long
  • Modern “downsized” production construction:
    • Gives uncertainty of piston position derived from the crank shaft encoder due to crank/block/maincap/ flex. This affects all combustion analysis numbers.
    • Bore roundness at high loads questionable
    • Wear out fast at high loads and abnormal combustion. Not the same brake results in long term tests start to finish.

Why don’t you manufacture a diesel and a gasoline head, like some competitors?

Consider:
  All the variable valve lift, phasing mechanisms available, or soon to be released
  Direct Injection trends
  Corporate preference to improve a given current head
  R&D on a new head/chamber/ports
  Expense of head development and continued updates
  Arbitrary bore size choice a head selection defines
We have decided it was lower cost, more flexible, and useful to use current OEM cylinder heads.
Those going they’re own way where a current OEM doesn’t work, will build they’re own, usually as a single cylinder prototype. Note that we can help w/ design and fabrication of quick turn billet or lost foam heads.

SC-1 vs competitor research single cylinder engines?

  • Large cost advantage
  • Replacement bearings / seals / bolts / spare-parts multi-source and reasonable
  • Ease of build-up / teardown
    • Engine features horizontally split, “Dutch dowel”, o-ringed construction; requires no gaskets or special tools
    • Uses conventional split bearings and standard seals
  • Balance mechanism
    • Low friction and Not rpm limited
    • Simple bolt on weights to change balance
    • No balance shaft inertia bending, gear drive, noise and torsional issues
    • Balance forces are resolved in crank rather than through bearings lowering friction losses
  •  All oil/water/electric/fuel ancillaries are remote
    • No parasitic losses of ancillaries (and their variances) affecting brake data
    • Initial warm ups can happen without engine rotation
    • Dry sump gives:
      • Tighter control of oil temp than conventional wet sumps
      • Vacuum ability for lowered windage losses
  • Cylinder Head Adapter
    • Wet liner
      • Supported round by adapter at high loads
      • Cooling passage CFD optimized
    • Large deck can use a 4 cylinder head, firing cylinder #2
    • Short deck for custom single heads and better access

Why do you fret so much over friction and wear on this design, when we only care about cylinder pressure derived numbers anyway?

We believe that low and, more importantly, consistent engine friction can contribute to more reliable and repeatable brake numbers. This in turn gives more weight to using brake data as a “check and balance” measurement, backing up indicated data.
Low ring/piston/bore wear is important from a blow bye perspective, directly effecting indicated numbers.
Oil particulates have been shown to effect many types of combustion.
Nice to have friction, blow bye, and oil consumption the same at the end of three months of testing as in the beginning.

What influences has modern racing had on this test engine?

  • Coatings
    • Antifriction main/rod bearings coatings
    • DLC piston pin, balance pins and fulcrums
    • PVD piston ring coatings
  • Dry sump advantages and crankcase windage and oil control design
  • High rpm, and high load longevity, issues and solutions
  • Piston oilers
  • Quick disconnect and AN plumbing
  • ECU sensor access and mounts
  • Assembly friendliness

No Starter?

Typically a motoring AC regenerative dyno is used, so none required.

Why is there a flywheel and engine mount for the AVL 365x shaft encoder?

Currently the longest lasting reliable shaft encoder available. Unfortunately expensive.

What are the bottom-end access ports for?

Side ports (and bottom port) are for extra separate piston oilers, piston telemetry antenna mounts, misc.

Why is the length close to a 3 cylinder engine?

Balance hardware on either side of firing cylinder

Does any cylinder head come with it?

Some of our customers develop their own heads and pistons. Typically we would supply the “short block” module for their head, with a generic cylinder head adapter.

Other applications might require a “standard” 4 valve head with a modern VVT. We would offer a couple of different cylinder head adapters and cam drive for this function.

Currently some of the cylinder heads discussed are Dodge-Fiat MultiAir, BMW double-vanos, VW TDI, Fiat 1.3L Multijet, Honda 1.5L i-DTEC….we welcome your input