19 replies to this topic

[R2D2]

hey guys. I know this question has been asked loads. What kind of performance figures can be achieved from a 998 using bolt on items and what these items would be. And also what parts best complement each other to get the best from the engine.
Cheers

[jaydee]

On a standard camshaft and bore size i doubt you'll see more than 55/60bhp ATF, that using a proper 295 gas flowed and possibly with bigger valves fitted, twin HS2, electronic ignition with optimized advance curve and a correct rocker geometry.

[BritishRacingGreen]

That depends what you define as bolt on, but 60 is probably around the top end with normal off the shelf parts.

[bmcecosse]

Why strangle it with tiny twin HS2s ?? Fit a large valve 940 head - with a 544 camshaft (check exhaust valve clearance - and sink them into the head as required) with a single HIF 44. Good LCB exhaust and balance the engine with a centre main strap - and you should have 80, maybe more if the head is 'worked over', at considerable revs of course !

[jaydee]

On a standard camshaft the HIF44 will be too big for max power. If you're fitting a 544, then yes, the HIF44 will be A LOT better.

[BritishRacingGreen]

or 'bolt' a turbo on and hit 100+ with mostly standard internals

[Cooperman]

Why strangle it with tiny twin HS2s ?? Fit a large valve 940 head - with a 544 camshaft (check exhaust valve clearance - and sink them into the head as required) with a single HIF 44. Good LCB exhaust and balance the engine with a centre main strap - and you should have 80, maybe more if the head is 'worked over', at considerable revs of course !

It's a 998, Roy, not a 1275 .
The question for the OP is whether you count a better cam as a 'bolt on' part. It's more like a 'bolt-in' and although the cam can be changed on a 998 with the engine in'situ, it is better to take the engine out to do it.
The standard cam is the limiting factor, even if you fit a 12G295 head and better carbs.
With twin HS2's (as a 998 Cooper) a 3-into-1 exhaust manifold and RC40 exhaust, a gas-flowed 295 head with C.R. at about 10:1 and a Kent 266 cam you should be looking at 55 to 60 bhp at about 6000 rpm
With all engine building, the quality and care with which you build the engine will be a factor in the final bhp figure. Match everything up well and assemble carefully.

[The Otter]

My 100,000 mile car with a standard cam, standard but skimmed 12G295 head (with guesstimated skim...), twin HS2s (vizardised) with ITG filter and radiused intake stub stacks, a cooper exhaust manifold and a non-ideal exhaust for performance, got 56 at the flywheel and 43 at the wheels. That was with an electronic ignition module in place of the points, if that helps at all for performance I'm not sure...

So going from Coopermans figures, either I got lucky with the C.R., or more likely the rolling road over-estimated my power a bit...

Edited by The Otter, 23 January 2013 - 05:38 PM.

[JustSteve]

By bolt-on suggests to me that you don't want to start stripping the engine.

The only things you can really do are to the timing and fueling. fuel injection and mappable ignition are the only improvements where you will see considerable gain, although they are pricey and the first step would be a 'stage 1 kit' . I doubt you could acheive more than 50 ponies at the wheels.


Ideally you need to do a little bit of surgery to the eninge to get the most from it. presumably you want something driveable on the road. the best places to start are a well ported head to allow the engine to breathe, coupled with a mild cam. fuel injection and mappable ignition are great if you're willing to spend money. slightly lighter fly will make the car more fun on country roads. Stick a decent exhaust on there, not a silly DTM any other massive exhaust. I'd be expecting from that to see about 60 stallions.

If you want more than that, then it starts getting pricey and less drive-able around town too

Edited by JustSteve, 23 January 2013 - 05:43 PM.

[Cooperman]

The problem with just considering and quoting bhp figures are that they don't give an indication of how quick the car will be overall on the road.
To get high bhp from a 998 one is talking about high revs and poor torque at low- to mid-range. You might get over 60 bhp at well over 6000 rpm by using a more aggressive cam, but to use that power you'll be revving between 5500 and 6500 rpm all the time.
You need to be achieving maximum torque at between 3500 and 4000 rpm with max power at around 550 to 6000 rpm with a 998. It is always ascrificing a bit of top end power to get more useable mid-range torque for a road car.

[R2D2]

mite have been a bit vague when i said bolt on. What i meant was replacement parts that dont require modification to existing parts. If that makes more sense

[86mayfair]

Hi guys,

I've just had my 998 block measured up and the bores have a lip on them which is to big for just a hone so I'm going to take it out. I'll go to +0.060" which gives about 1050? I'll put a worked 12g1295 head with a CR of 10:1 and 1.3:1 roller rockers on too. A single HS4, probably on a minispares manifold, a Cooper Freeflow manifold, single box RC40

I know that there are other factors to consider but what would you think this engine would produce with a Kent 276 cam?

Edited by 86mayfair, 03 February 2013 - 06:40 PM.

[Gr4h4m]

Strap a supercharger on and with std internals and a skimmed 295 I hit 60 at the wheels! Cheap power no extra revs needed IMO. Not bad from an engine built in 1969 :)

To up the power the. Takes ££££

[ACDodd]

Ok twin hs2 carbs do not strangle a 998! I run these on a classic race midget and we get 100+ hp! They are very good for a small bore motor, and will out accelerate a single su every time as long as they are perfectly tuned. Power figures and stopwatches are too different things when comparing su combinations!

Ac

[Cooperman]

The confusion seems to come from the mistaken belief that ultimate bhp is what should be aimed for in a road car. Whilst ultimate bhp is very important for a track car, for the road its good mid-range torque combined with max power coming in at rpm's which will be used regularly during normal driving.
To make a nice useable 998 a good mid-range cam is essential and a Kent 266 would seem a good bet combined with a 12G295 head and twin HS2's, etc.