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A Big Bore Throttle Body is a simple and cost effective way to improve the throttle response, increasing the bore size from 64mm to 68mm, no additional work or adjustment is required, it is a bolt-on option. Removal and Refit is relatively easy, insert new gaskets and be careful of the water channel torque screws, they heat up over the years and can snap off. The coolant section is used to heat the throttle in low temperatures and prevent it from seizing, this is normally only required in -10deg weather.-

The Original 64mm and Rebored 68mm Throttle Body with bigger butterfly.


The Z1 shares its manifold with similar engined cars of the era but the down pipe, cat and pipework to the rear silencer are one piece and unique to the Z1. If headers are fitted you would need fabrication work to fit them to the existing system or get a new centre section. You would also need to be mindful of the length of the headers, not just the width, so that the flange on the collector isn't the lowest point underneath the car. An engine is effectively an air pump - improving flow in one area will have little effect if there are bottlenecks elsewhere. The oxygen sensor would need to be retained to keep the ECU happy. Headers will be louder than the factory manifold - the cast iron is very good at absorbing some of the harshness of the exhaust pulses - fairly thin walled stainless steel isn't. The Supersprint will bolt straight on as well as any LHD E30 325.


This is a chip emulator. It replaces the original chip whilst the best settings are found and stored for download onto a new chip.

In this example, the car was taken to AmD near Oxford to have them re-programme the ECU. This is the car running on a rolling road Dynometer with a chip emulator in between the engine management system and a portable computer. When the best figures were obtained the settings were saved and then re-programmed into a new eprom for the system. THIS WORKS. See plots below.

BHP curve Maximum Power Speed 5897 rpm

Power at flywheel 182.BHP
Was 175 BHP

Power at wheels 135 BHP

It's the RED plot that is the one after the AmD re-programming

Maximum torque speed 4206 rpm

Maximum engine torque 182 Ft/Lbs
Was 172

Tuned by AmD

In terms of drivability the car feels much livelier due to the increased width of the top of both of these curves. What isn't shown on the charts is how the partial throttle performance improved, it is as if the engine is a couple of hundred cc bigger.


This is the K&N Cone filter, in this configuration it does little for the performance but it looks and sounds great. When the throttle is opened the filter sucks all the air under the bonnet which is Hot, the way around that is effective heat-shielding and ducting. Ideally place the filter in the space on top of the radiator ducting, then fix an inlet duct through the original bulkhead hole up to the air meter. The filter in the picture is the 57i kit for the E30 325i. The bracket to hold the AFM will need slight alteration.

K&N Filters can be obtained from Moseley Motorsport