Personal intro
Intro technics

Exhaust systems
Exhaust overview
XJ Saloon S1,2,3
XJ40 (AJ6&V12)/X300
TT exhaust explained

The Jaguar V12
V12 Performance
Stretching the V12
E-type EFI conversion
D Jetronic
Lucas EFI
Vacuum advance
Ignition systems
V12 throttle linkage
Article: V12 Engine
V12 Archives

The Jaguar AJ6
AJ6 Performance
3.6 Richness
AJ6 fault codes
*  AJ6 Archives

The Jaguar XK
XK Performance
Article: XK Engine
Article: 4.2 EFI

The Jaguar V8
V8 Performance

AJ6 Superchargers
Supercharging article

Suspension & Brakes
ECU repairs
Miscellaneous bits
Prices & ordering

Updated August 2016
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1. An early prototype stage in the AJ6 engine gestation process. This is actually based on a variant of the XK cast iron cylinder block but the head layout already had features like the head bolts passing through the camshaft bearing caps that carried over to the AJ6 design. It can be seen that the exhaust and induction manifolding was still handed in the way of the XK.

2. One of our prototype 4.3 litre large bore conversions on the AJ6 3.6 built in1987. It also has a prototype of our multiple throttle system machined from solid. This photograph inspired our AJ6 Engineering logo.

3. Here is the same throttle system installed on a 3.6 XJ-S. This produced a power gain of about 50 b.h.p. from an otherwise standard engine when used with a less restrictive exhaust system. Intake pipe length was critical - shortening the trumpets by 1.5" reduced the power gain by nearly 20 b.h.p. Adjustable length trumpets were used to find the ideal dimensions to use.

4. The production version of the multiple throttle system with the main assembly machined from a casting, chrome plated bright-work and a custom made K & N filter.

5. A prototype of our Ram Plenum induction system for the AJ6 engine. This was a highly resonant tuned pipe system designed to work with the Lucas 9CU and 15CU engine management systems. The restriction of the hot wire airflow meter was resolved by adding a bypass orifice to double the breathing area, and some electronic changes to compensate for the different load signal. The throttle was 3.5" diameter mounted on ball races to overcome the effects of vacuum induced friction on the spindle. When on song it was incredibly noisy, to the point of being painful, and only became civilised by adding a resonator inside the intake duct. It produced a very strong power band from 3000 to 6000 r.p.m.

6. This shows the individual tuned length pipes of the Ram Plenum system - before the plenum chamber was welded in place. The wave action within the pipes was augmented by powerful resonances in the main intake duct.

AJ6 Engineering, 60, Henshall Road, Bollington, Macclesfield, Cheshire SK10 5DN, England
Email, Tel/Fax:- 0044 (0)1625 573556