The E-TORQUE Cylinder Head

An Aerospace quality product cloaked in vintage garb

“The E-Torque Cylinder Head is designed for the Jaguar connoisseur who desires modern performance and everyday drivability without compromising the authenticity of a vintage car.” - John Stowe

Performance increases of 100 hp typical for 4.2 liter engines with stock 9:1 pistons, triple SU carbs, and original cast-iron headers

Even more power possible with Weber carbs, EFI and higher flow exhaust systems
Special CP-Carrillo® pistons adapt the E-Torque Cylinder Head to the bore spacing of 3.8 liter engines while raising compression ratio to 11:1
This cylinder head comes with chill-cast, seven-bearing, Mild or Street Performance camshafts. Mild Performance cams provide more bottom end torque with great idle and low speed performance. They are designed to work with SU carburetors that require higher vacuum. Street Performance cams deliver less bottom end drivability but higher peak power. These camshafts work well with Weber carburetors or best with Electronic Fuel Injection (EFI).

Original limitations have been overcome, providing improved performance and efficiency
Combustion chambers properly centered over each bore for 4.2 liter engines
Raised and reshaped ports for improved flow, increased compression ratio, and increased squish area
Twin Spark option available for improved power, drivability, efficiency, and emissions
Aerospace quality component, chill-cast in a 3D-printed sand mold
Single-spark models can be converted to Twin Spark models at any time

SHOP E-TORQUE CYLINDER HEADS

This 4.2 litre Single Spark replacement Cylinder Head is perfect for any one looking to upgrade their XK Jaguar engine by 100 hp without removing the engine or needing to upgrade the ignition system. If your engine’s bottom end is in good shape, this cylinder head is designed to replace the original Jaguar head without further modification and at minimal expense.

This model is exclusive to the 4.2 litre block, as the bore spacing is different on the 3.8 litre block, which requires custom pistons be fitted.

Although this head can be ordered as a Twin Spark model, that requires, either the E-Torque Twin Spark Ignition System, or Electronic Fuel Injection to control two sets of spark plugs. The main advantage of Twin Spark technology is to allow one to increase the compression ratio. Since Twin Spark adds a lot of expense, and since, with stock Jaguar pistons, you can’t get to the desired 11:1 compression ratio, we default to a single spark head configuration for this model.

With stock 9:1 Jaguar pistons, (which only made 8.7:1 compression), you will get a 10:1 compression ratio by replacing the original head with E-Torque’s Replacement Head. Your intake valve diameter will go from 1.625” to 1.950" and your intake cam lift will go from .375” to .421”. It's a great choice for anyone looking to get more power and better drivability from their stock XK engine with a smooth idle and great bottom end torque!

You can choose between Mild Performance and Street Performance cams. Mild Performance cams will create sufficient vacuum for the SU HD8 carbs. Street Performance cams are best for EFI!

4.2L Replacement Head

This model of the E-Torque Cylinder Head is designed for those who intend to pull their engine out to do a total rebuild. This kit comes with CP Carrillo® pistons that are custom made to work with the unique combustion chamber of the E-Torque cylinder head. This product can be ordered in Single or Twin Spark configuration.

Twin Spark allows one to run a higher compression ratio because it will knock 9 - 10 degrees of spark advance off. We therefore limit the single spark head to 10:1 compression and the Twin Spark model to 11:1.

The CP-Carrillo® Forged pistons in this kit, will be made according to the desired compression ratio. Your intake valve diameter will go from 1.625” to 1.950" and your cam lift will go from .375” to .421” (w Mild cams or .466” w Street Perf cams). It's a great choice for anyone looking to maximize performance of a normal stroke, XK engine.

E-Torque also sells refurbished XK crankshafts. These have been crack-checked, had their oil passages cleaned, their journals ground and polished, the journals Nitrided (hardened). Then they have been re-balanced and the rear main journals are re-machined to accept a modern rear oil seal. These cranks require a core exchange.

Although it is not necessary with this Upgrade Kit, it is always good to replace the original crankshaft with a billet steel version. First - a new crankshaft will get rid of the rope rear bearing seal that causes chronic oil leaks, and second, old crankshafts can break from fatigue depending on how much abuse they have seen. And billet steel crankshafts will also tolerate more RPM than stock cranks so you get an extended top end typically a Red Line of 6,200 RPM instead of 5,500 for the stock crank.

Billet Steel crankshafts can be ordered in 3.8 litre (standard stroke), 4.1 litre (stroked 3.8 litre), 4.2 litre (standard stroke) or 4.7 litre (stroked" 4.2 litre) configurations.

3.8 - 4.2L Upgrade Kit

4.7L Upgrade Kit

Stroked 4.2 Litre

This 4.7 litre, Twin Spark cylinder head is perfect for anyone looking for neck-snapping power from their XK engine. Stroked engines produce a lot more torque than standard stroke engines, and the do it at lower RPM.

With the CP-Carrillo® Forged Pistons in this kit, you will have 11:1 compression. Your intake valve diameter will go from 1.625” to 2.000" and your intake cam lift will go from .375” to .500”.

This high performance head has a special chamfered combustion chamber and matching piston design. This allows the very large intake valve to flow sufficient air required to get to over 400 hp. (see image below)

This Upgrade Kit will require that you purchase a 4.7 L Stroker Kit. This is perfect because it is always good to replace the original crankshaft with a billet steel version. First - a new crankshaft will get rid of the rope rear bearing seal that causes chronic oil leaks, and second, old crankshafts can break due to metal fatigue from past abuse. Billet steel crankshafts will also tolerate more RPM than stock cranks so you get an extended top end typically a Red Line of 6,200 RPM instead of 5,500 for the stock crank.