Can the engine of an S4 fitted with Strombergs......

[mark030358]

be modified to produce say 140-150bhp from track racing? I know it ok with webers but not sure with Strombergs.

Just gone and bought an S4 with my mate as a track day play thing )

Mark

72 Sprint

1/2 68 S4

[steveww]

Should be able to get around 140bhp with a bit of work. You will get a fatter torque curve with the Strombergs. You will need to look at the brakes and suspension first though for track use.

Have a look at Tony Thompson's web site for all the racing goodies.

[rgh0]

Hi Mark

Not many people have done serious development work on Stromberg heads so hard to say what they can achieve. Steve has done more on this than most people so his 140hp is a good guide as to whats possible at a resonable price, just doing the traditional hot up items of high lift cams, big valves and porting and good exhaust headers and ensuring every other detail is right and optimum in terms of things like mixtures and ignition. Incremental cost above a standard engine rebuild is small and approaches zero if your current engine is well worn and needs new valves, guides, cams, buckets etc and you do the porting yourself.

Based on the MG race guys getting around 180hp from a siamesed port B series 1860cc engine you should be able to get to around 150hp and may be more if you really worked seriously on extracting maximum horsepower

However to get to those levels the $ spend rapidly increases as you probably need to go higher lift again with short duration "scatter" cams which no one has done on a stromberg twink to my knowledge and also build a high compression steel bottom end to give you a reliable 7500 rpm and 12:1 comp ratio and lots and lots of detail engine work. Incremental cost above a standard engine rebuild would be around A$10000, US$7500, 4500 pounds.


In the end unless you just want to find out what you can get out of a Stromberg head, if your seriously pursuing plus 150 hp its probably cheaper and easier to send your head to John McCoy at Omnitech in the US and have the Weber conversion and CNC porting done by him rather than exploring new regions in engine development yourself.

However you will improve your track times much quicker and cheaper working on handling and on driver skill first before you start seeking big horsepower which is always expensive in proportion to the track time improvement.

Whatever you do, getting an Elan on the track will be lots of fun
regards
Rohan

[steveww]

Good advice as always from Rohan. Tune the nut behind the wheel first

Even in standard trim the Elan is pretty quick even by modern standards, around 7.5 secs 0-60.

Don't get hung up on horse power (bhp) it is torque that gives the acceleration, power that gives the top speed. Loosing any excess weight is free power & torque.

Again for track use the Elan needs some work to the brakes and suspension. Check what you are allowed to do if you are planning to enter any championship. For track days only just about anything goes apart from being too loud

Fitting adjustable dampers and slightly stiffer springs on adjustable platforms is a good start. Swap the front brakes for those off a +2 and remove the servo is a cost effective way of improving the brakes. Lots more info on http://www.stig.uklinux.net/

[mark030358]

Steve and others,

Thanks for the replies. Fully intend to do the suspension stuff but why does removing the servo help braking.

cheers
Mark

[steveww]

Removing the servo and fitting the bigger +2 brakes improves the braking in a number of ways. The larger pad and disk area improves the thermal capacity and reduces the habit of the rear locking first. With the servo gone the pedal is firmer and brake pressure is easier to modulate, this helps with extreme braking when on the track and makes heel n toe changes a lot easier.