Audi 4000 Turbo quattro Conversion

The Intro

The Project


Total Bill

Engine Specs

Special Tools

Current Specifications

These are the after project specifications as they stand now.  These are not in any real order just as they came to me.

KH 5 cylinder 2.14 liter


Stock part - thermal barrier ceramic coated tops, moly coated skirts

Tops smoothed prior to coating


Stock parts - thermal barrier coated tops

Combustion Chamber

Valve seats unshrouded, slightly reshaped, all surfaces smoothed and then thermal barrier ceramic coated 


Gasket matched with moderate material removal,

all transitions smoothed, 

exhaust ports thermal coated

Intake Manifold

Gasket matched TB and ports, bead blasted and clear coated

Exhaust Manifold

Extensive material removal to gasket match and open ports, 

thermal coating

Throttle Body

Removed "ramp" (see text) and blended bore to IM


Stock unit - water cooled - untouched

Boost Level Stock (about 6 to 7.5 psi)
Waste gate Stock KH unit with stock spring
Turbo down pipe Mandrel bent 3" with 3" SS flex joint
Bypass Valve

Stock Saab 9000 turbo unit


Large single pass front mount aluminum Isuzu unit

Air charge piping

2.25" mandrel bent, painted exhaust tubing

Air box

Top from Rabbit GTI, bottom SS sheet metal

Oil Cooler Stock KH unit

I don't have any performance numbers for the new motor right now, but I will try to in the future.


Baseline Specifications

These specifications come from several sources.  The sources are listed at the bottom of the page.

Original 1985 Audi 4000 quattro engine (stock)

Engine Code JT
Displacement 2.22 liter (136 in^3)
Output ratings 115 BHP SAE @ 5500 RPM
126 lb-ft @ 3000 RPM
Bore 81 mm
Stroke 86.4 mm
Compression ratio 8.5:1
Valve Train 10v SOHC - Hydraulic lifters
Valve size Intake - 38 mm
Exhaust - 33 mm
Throttle Body size*
(spread bore)
35 mm primary, 52 mm secondary
Induction Naturally Aspirated
Fuel system CIS-E

1985 Audi 5000 turbo engine (stock)
Engine Code KH
Displacement  2.14 liter (131 in^3)
Output ratings**  BHP SAE @ 5500 RPM
 lb-ft @ 3000 RPM
Bore 79.5 mm
Stroke 86.4 mm
Compression ratio 8.3:1
Valve Train 10v SOHC - Hydraulic lifters
Valve size Intake - 38 mm
Exhaust (Sodium filled) - 33 mm
Throttle Body size*
(single plate)
62 mm
(2% less area than JT TB @ WOT)
Induction Turbo with Intercooler
Turbo model  Water/oil cooled KKK K26
Intercooler inlet/exit size* 56 mm
Intercooler dimensions (mm)* 335 (w) x 181 (h) x 84 (t)
* Measured by eye with a tape measure.  Could be off by a mm or so.
** Have found conflicting information on this.  Also found 104 hp @ 5500 rpm with 150 lb-ft @ 2500 rpm, but this may be for oil cooled only KH.

Base line JT Road Dyno run.  Here is a before swap run using Road Dyno (see links).  Absolute values may be slightly off, but this gives a good idea of the shape of the curve.  This was done on a flat section of road in second gear.  You can see it gets very weasy at high RPM.  I think this was before I changed the lifters.

Robert Bentley 4000 service manual © 1989
Robert Bentley 5000 service manual © 1988
My own measurements