6 replies to this topic

[Haynes]

We are having my son's 998 engine rebuilt.  Still debating either a standard build, or putting in a slightly better cam 266, SW5 etc.  May fit a stage 1 kit now or we could get it running first on standard exhaust etc and add kit later.  Balking at the cost of a modified head, at the best part of a grand really not sure if this is worth doing although cost is off set by the fact that unleaded conversion and standard head rebuild is going to be £300-£400.  Long term the plan is rebuild engine, get it back on the road for summer, then concentrate on bodywork and suspension mods.  Once the rest of the car is sorted, we could then revisit the engine and consider a 1275.

 

However my question is what other modifications should we definitely do or are these unnecessary on a 40-50bhp engine:

 

Duplex timing chain?

Centre main strap?

Centre oil pick up?

Is it pointless fitting a 266/SW5 cam with a standard head?

Lighten the standard verto flywheel?

 

Anything else we should do to the block while the engine is out?

 

[ACDodd]

Duplex chain no point.
Centre main strap no point,
Centre oil pickup, good idea.

Fit the SW5-07 cam then fit a better head later on.
Lightening and balancing the stock flywheel is also a good idea.
Better still is to fit a 1098 crank and pistons while you are there. Best bang for buck going.

Ac

Edited by ACDodd, 05 April 2019 - 12:29 PM.

[Ghostrider]

A good 998 is great fun, equally as a 1275 in my opinion, but it takes a fair bit of work to get to that sort of level. If your looking to get more power and a better engine all round, the head is probably the best place to start, especially with a stage 1 or nice RC40 exhaust. 

 

A good head on a 998 makes all the difference, not just in power but in responsiveness too. Either a 12g295 or 12g202 will do nicely, but 295's are quite costly and a well modified 202 just as nice, plus its much cheaper. 

 

However just bolting it on will not really do anything, to get the best it will need to be skimmed to achieve a good compression ratio, flat top pistons will require slightly less skimming to get a good CR of something like 9:1 or 10:1 whereas dished will require a bit more, bumping the work costs up. Gas flowing the head will give a much nicer response too and is a must really if you're going through all of that. I done this recently with a 202 head that I purchased for £40, although I did the machine work myself at Uni, A few machine shops quoted about £60+vat for 30 to 40 thou skim but this is something that will be different for everyone.

 

Fitting a better cam really needs a good head to get the best out of it, I'd personally recommend the mini spares evo-001 cam, its a cracking cam. If your doing all that you may as well fit a duplex, especially if your upping the power.

Ultralight or lightened flywheel will work nice too, I use an MED ultralight one, but again you'll notice some change but the most will occur with a good gas flowed head with a decent CR.

 

Hope this offers some help,

 

Jacob

[Haynes]

Talking this through last night, my lad has decided to do a fairly standard build for now which mainly means not spending a lot on a modded head. He wants the car to evolve and improve over time and sees the benefit of sorting the handling out first. I'm thinking might be worth putting in a 256 cam.

Will do centre oil pick up, new pumps etc.

Any other 'dosent cost a lot but well worth doing' things whilst egine is out?

[andyapanel]

It is worth remembering your insurance company will need to be notified. I would check to see how the premium will be effected by each proposed modification.

I have a standard 998 in my Racing Green, but I have a Minispares lightened flywheel, Maniflow Cooper free flow manifold, Minispares inlet manifol, K+N and and a Stainless RC40. These mods are not particularly expensive to fund each year 

 

David Vizard's books are very enlightening and there are two useful books in the Speedpro range by Des Hammill ("Power Tune 998 A series" and "Power tune minis on a small budget.")

[G'Racy]

Does your engine need a rebuild?
If not, and you say you want the car to evolve over time, why not have the stage 1 kit first, allow for set up on a rolling road.
Then as funds and time allow, add a new cam, and maybe a 12g295 head modified for unleaded.
All this can be done without the effort and expense of removing/rebuilding the engine.

[Haynes]

Engine was belching out smoke and burning oil hence decision to whip it out and get this sorted.