Conversion - T2 Zumwalt

 
Rev - Nov 11, 2017

By Jan Zumwalt (EAA #66327)

 

See Also

DIY 1800cc Mini-stroker

Specifications
HP Rating: 70 @ 3400
Continuous HP: 70 @ 3400
Fuel min octane: 91 octane auto or 100LL
Oil: multi-grade 20/50
Bore: 92mm (THICK WALL 88mm cylinder )
Stroke: 69mm
Displacement: 1835 cc
Firing order: 1 – 4 – 3 – 2
Compression ratio: 8:1
Spark plugs: 12 X 3/4 reach DCPR7E
Carburetion: Your choice
Ignition: Single or dual ignition
Timing: BTDC 25 degrees
Alternator: 30 amp
Battery: 12V min. 20 amp
Crank flange: SAE #1 4-3/8″ bolt circle
Dry weight: 170 lbs.
Max rpm: 4000 (5min)
Cruise rpm: 3200 +/- 200
Idle rpm: 900 +/- 50
Oil temp min: 130 degrees F
Oil temp max: 220 degrees F (measured at sump)
Oil pressure min: 10 lbs/1000 rpm
Oil pressure max: 80 psi
CHT cruise: 350 – 375 degrees F
CHT climb: 450 degrees F
EGT full rich: 1250 degrees F
EGT max; 1400 degrees F

Introduction

If your looking for performance improvement over the stock 1600cc but need a minimum cash outlay, this may be the engine for you. This engine recipe uses mild modifications which translate to super reliability. Under no circumstances do I recomend any kit that supposedly provides everything for an engine overhaul (bearings, gaskets, etc). These "kits" use inferior parts and may even have incompatible parts!
This link (Engine Design Sheet.pdf) is also at the top of this article. It is a form that helps design your custom engine.

  

Case & Cylinders

It's possible NO CASE MACHINING will be required on newer cases, but the older the case, the more likely minor clearance will be needed for the rod bolts near the cylinder windows. The use of Thick Wall 88 cylinders guarantee a (no machining) fit in a standard VW case hole. Thick Wall 88's are thicker than the stock 85.5mm cylinders, so they have extra safety and heat resilience needed for aircraft use.

Heads & Exhaust

The heads will have to be machined to fit the 92mm cylinder tops. The heads you select will depend on which carb(s) you use, and the cam you use should be selected last! Please note that the exhaust system you are going to use will determine the best heads to select too!  For example, if you are going to run 1 3/8″ exhaust, than your best head selection will be stock dual port heads, or L3 dual port heads. If you bump up to heads like the L5 dual port heads, you can run 1 1/2 or 1 5/8″ exhaust. You cannot use a big valve head on any engine without a 1 1/2″ or larger exhaust. This is an example of where your choice of exhaust system will affect what engine you can have it bolted to!

Crank & Rods

The 74mm crank is a drop in with no machining. You have to go into the rod length issue knowing there are benefits and drawbacks to each one. With the 5.325″ rods, you will have an engine which is stock width, and stock length push rods will work! But you will have crankshaft counterweight interference with the piston skirts. The skirts can be narrowed to achieve .040″ clearance. You can minimize this with the use of the 5.4″ rods, BUT this makes the engine wider and you’ll need longer than stock push rods.

Carb

You can use any of the appropriate carbs, by Zenith, RevFlow, Makuni, Bendix / Stromberg, etc. This engine recipe was a go getter when tested with dual 2bbls (Dual 36, 40mm DRLAs, or 40 IDFs). During the mock up stage, you’ll have to order cylinder base shims to get the engine’s deck height between .040-.060″; the target height is .050″, so if you are off +-.010″ it’s not a big deal.

I have provided links to some products sold by http://vwparts.aircooled.net. I do not consider necessarily as the best source - I always shop around!!! Use this list as a base; simply change the carbs, heads, and cam, for a wilder or milder engine as you see fit. http://vwparts.aircooled.net offers free consulting and encourages engine builders to call them!
Click HERE if you want to see a list of all our engine combos to choose from!
Complete list of parts used in a VW long block!

Lifters must match the cam used! The cam you use needs to be chosen with the heads you are using, and the carburetor(s). The more carburetion you have the more cam you can use, since the increased carburetion will retain a smooth idle. If you stay close to the stock carb, use a “cheater” cam, such as Cheater Cam for Power
or Engle’s Version of the Cheater Cam. If you have increased your carburetion to a progressive or dual 1bbls, you can do something like Web Cam 218/119 camshaft (If you have dual 1bbl carbs). With dual 2bbls, don’t go bigger than the Engle 110 UNLESS you have increased your heads to something like the L5 Cylinder Heads. The Web Cam 163 Camshaft  is another very good choice. Choose a 108LC for a beetle/ghia, but a 105LC for a Type 2 or Type 3.

OR

(Re-use the ones you have if you want to!)

There is a link here and at the top of the page for a parts selection sheet to help you from forgetting some important item.