Big Bore Throttle Bodies

News from Bexley Motor Works

Cheapest power hike on the market?

We all know about making our cars breathe better for better performance and few serious owners would not have upgraded their air filters, and exhausts perhaps had their heads gas flowed and of course the whole package ‘chipped or the existing ECU re-mapped

E30 readers might have noticed that a lot of car modification specs recently have been listing a ‘bigger throttle body’ as part of their performance package. Alpina used these as part of their highly successful and very quick 2.7 cars so there is some pedigree for such a modification.

Log on to www.e30zone.co.uk and you find much talk of this modification and even how to get your hands on one. But are they any good? How much extra power will they give? E30 specialist Bexley Motor Works had the ideal opportunity to test one when one of their regular customers posed this very question. He had sourced one himself from the e30zone, Nigel and Jags decided to put it to the test on their now famous rolling road

The car in question was an ’89 325 Sport with one of their 2.7 conversions. (The engine had been originally been in the customers 323i and been swapped over along with suspension, wheels, interior, etc when rust finally brought the demise of the donor car.) It has the usual ETA long throw crank, 323i con rods, Mahle lightweight pistons, gas flowed head, K&N panel filter, Scorpion back box and had been re-mapped.

The test comprised a simple before and after power run. The first test with the standard 325 item showed the car to be producing a very respectable 234.6 bhp at 6154 rpm and 220.8 lb/ft of torque at 4645 rpm. This is a lot of power from such a package which is largely down to a combination of Jags mechanics and Nigel’s expert mapping over the years.

At first sight, the bigger throttle doesn’t look that much bigger and there was some skepticism as to what difference it would make. It’s quite a simple job to fit - only just enough time for coffee and the car was ready for the second run!

Nigel was beaming when the figures popped out of the computer. This simple mod had hiked the bhp up to 240.7 at 6282 and the torque up to 227lb at 4470 rpm. The curve characteristics had changed for the better too.

The proof of the pudding is of course in the driving and it is reported that throttle response has improved noticeably, power being more freely available and motorway cruising seems to be ‘lighter’.

So what did all this cost? The part was sourced from one of the e30zone members on an exchange basis for £120 plus the cost of sending the old part back.

Nigel reckons his is really a worthwhile modification. Its not easy getting 7 or 8 more bhp from a part when you’re already working at the top end of an engine’s capability so this has perhaps got to represent the best £ per bhp available!

Full reproduction quality pictures and power print-out available.

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More Information

More information available from Nigel French or Jags Bhamra

Bexley Motor Sport, 10a Lion Road, Bexleyheath Kent DA6 6NR

Tel: 020 8304 9797 Fax: 020 8304 0345 www.BMSport.com