10 replies to this topic

[blister]

what are double valve springs for and do they increase power?

[Bungle]

no the won't give you more power

they may let you rev more with out getting valve bounce

or the may be fitted because a higher lift cam is used or high lift rockers because they have less coils theres less chance of the coils touching when fully compressed

[blister]

ok well me and my dad have got a 998 being built for my older brother and we was wondering cheapest way of increasing its power it is a 998 with play mini exhaust and stage one and we want all the performance upgrades that can be got for a 998

[Bungle]

hotter cam and pocket the block for a 1275 head

[blister]

dont really want to pocket it what is the best spec head for a 998 with stage one and twin hs2s with sw5 swiftune cam

[mini-geek]

well seams as you will have the engine out to put the cam in you might as well get the block pocketed as the cost of a modded 998 head will be a lot more that pocketing and a std 1275 head

not too sure what 998 heads you can get some one else might know better

[blister]

well i was going to grind at the head myself and get machist to do what i cant just want to know what is bests sizes and stuff for head at that spec engine

[ginigwunkle]

you can get stage 3 and four heads for the 998 like the 1275 ones, they are about the same price as 1275 ones at arround £3-400 you may aswell get the block pocketed and put the larger std 1275 head on at much less cost as you xcan pick thm up for 20-30quid!

[biggav]

you can use the 998 block with the 1275 head as someone else said and get the block pocketed for £60-100 so the valves don't hit the block, you may also need to get the head skimmed to bring the compression ratio to the right level.

to be honest with what you will need to spend to increase power (and insurance) i'd personally just get a 1275 and go from there.
my wife has had her 998 for less than a week and i've already got a 1275 lined up... and cam... and head.... inlet, exhaust etc etc. I considered doing some work on the 998.. for about 2 seconds but whatever i do to it i know that i'll always be annoyed that i didn't just start with the 1275 and be done with it.

If you haven't already done so, spend £10 on "Tuning the A-series engine" by David Vizard. it compares all the different heads, exhausts, inlets, carbs and cams against each other and explains how and why they do what they do and allows you to make your own decisions on what you need

[blister]

so i get a 1275 head and can i have a empty block pocketed and then i just put it over my pistons i dont really want to take the engine out noow cant get a hoist and not really got cash for a cam

[The Matt]

Nope, you can't fit a block over the top of the pistons. Pocketing the block should be done with the engine out and stripped, but people have done it with the block in place and fully built up (bodging).

If you've got the engine still in the car, the block pocketing isn't the ideal solution for you. Personally, it's still what I'd do though. I'd actually get your spare block pocketed, build that up and then fit it.

However, if you really don't want to take your engine out, you're limited to a stage 3 or 4 small bore head. They do go on ebay now and then, but they're an expensive way of getting a few extra horses.