modifiying a 924 (non turbo)

[chubbs7uk]

hi
I have recently brought a 924 on a 78 plate. It does need some work doing on it but im curious to know what mods can be done to give it a bit more ummph. I have thought of a couple of ideas but how feasible they are im not sure. Firstly how adaptable is the k jetronic system, it does not seem complicated due to there being no ecu.
My first idea is to polish and port the head and get some larger vales along with more aggresive cams, and at the same time increase the pressure in the injectors by getting a higher pressure fuel regulator.
As the engine is vw/audi maybe even get a 16v head and have a ecu set up on it or even get some carbs as replacement for the k jetronic system.
So if anyone has any experience in the 924 please do share ur ideas and if u dont feel free to contribute anyway.

[AJLintern]

Have you thought about turning it into a 924S by putting a 944 engine in it? Not sure how much a secondhand unit would cost. The 924 was a bit lighter than the 944 so the 163BHP 2.5 engine should give better performance, in theory.

[NineMeister]

Sorry to break it to you Chubbs but the cheapest way to tune a 924 is to sell it and buy a 924S, so getting a newer car with better brakes and stronger gearbox into the bargain.

We used to sell tuning goodies for the 924. You can fit a ported head and equal length exhaust manifolds, with K&N filter, large bore throttle body (1800 GTi Golf), fast road cam & modified warm up reg for around 140bhp. BUT that lot will cost £2000, for which you can have a reasonable 924S.

Forget tuning the 924 engine, use it as it is, totally reliable & reasonably economical, then sell it and upgrade as soon as you can.

[chubbs7uk]

thanks for ur opinions, the 2.5 ltr 944 engine seems like a good idea. A specialist in porsche parts called porsche shop located in the midlands sell a product which is an extra throttle body and they claim that it adds 10% to the performance. Now im not sure whether they mean bhp or torque and whether it is low end or upper end torque. But on the grounds of presuming its bhp that would be an extra 12 bhp bringing the total bhp to 137. I know exhausts and air filter combinations can add another 10 bhp. I am actually only looking to about 150 bhp, cause i dont really wanna be spending hard earned cash on a new clutch and brakes every six months.

[NineMeister]

Chubbs,
Please read my comments above until you understand the implications. You will NOT get 10% from a K&N filter and a throttle body, this is bulls**t. We got 12% from a head, exhaust manifold, K&N, throttle body, warm up reg, flow matched intake, (and loads of development) and it costs £2000.
We also fitted twin weber 40's & programmable ignition & got 139bhp. We then fitted throttle bodies and full engine management & got 141bhp. We tried three different cams and all we did was lose torque.

These engines are great, they go on and on and on, but forget about tuning them, it is just not worth the effort when you can buy a faster car with better brakes for less money. Anyway, enough of the lecture, it's your car and your choice, and I would love to be proved wrong, so if you can buy your way to 150bhp for £200 do it and I'll pay for the parts myself!

[AJLintern]

Hmmm - N20?

[iguana]

I just looked at a sweet 924S for a mate 90,000 miles all mots, reasonable history up for £1000. The S has the same 2.5 engine as a 944 (with slightly lower compression in the early cars) and 150bhp/163bhp as standard so why mess about with an engine that is notoriously hard to get any gains from.

>> Edited by iguana on Monday 25th November 08:42

[chubbs7uk]

ok nine i get ur point, i just read ur profile on being a porsche specialist. So will a 944 engine mate straight to the torque tube of a 924 or will it need an adapter plate.
Also does anyone have any experience fitting non porsche engines in to porsches , if so what have u fitted?

[larry49]

AJLintern said:

Have you thought about turning it into a 924S by putting a 944 engine in it? Not sure how much a secondhand unit would cost. The 924 was a bit lighter than the 944 so the 163BHP 2.5 engine should give better performance, in theory.

The K jet is tuneable, I have experience of the Audi 5 cylinder with K jet....I installed a larger cold air intake to the front of the car behind the grill, I opened up a secondary air intake in the airbox to the bottom under the front valance, I radioused the air inlet to the AFM below the flap then I figured could I raise the flap height and increase the flow and fuel so I cut away a small amount of the recess in the cone where the arm sits so allow the arm and flap to rise further thereby allowing more air and fuel..........lastly I removed the restrictive stop under the flap and replaced it with a strong 4mm rod bolted on the underside of the AFM, the flap height could still be adjusted by bending the rod up or down to get the correct flap height.....these modifications did increase power a little, the throttle body I polished, the inside, knife edged the butterfly and reduced the butterfly shaft size, this led to more performance......finally I went the whole hog and polished the hell out out of the inside of intake manifold...I invented a way of polishing it completely, the whole runner length and phelum chamber, this gave me astounding gains in low end torque, I could pull from 10 mph in 5th to top speed, I even only once pulled from standstill in 5th obviously slipping the clutch up to 10 mph

Edited by larry49 on Sunday 11th April 19:02