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capacity increase

1K views 10 replies 6 participants last post by  James&Nick 
#1 ·
Hello all

I'm in the process of rebuilding my 16v engine and wondered about increasing the capacity a bit.

Looking at the AH Motorsport website put me off as the prices were around £4000+vat, however I just found out that Brunswick motorsport do some 1800cc pistons for about £500+vat.

What I wondered was is it worth it? I was hoping that initially the engine could run on the standard ECU as its only an 88cc increase, I'd then upgrade to a programmable setup later (I appreciate that this will be required to make the most of the increase). The price of the increase isn't that much more than new standard size pistons and I think that the standard fuel pump and injectors should be ok. I wasn't planning on any rod/crank ungrades other than new bearings etc as the car is only going to be for fast road use and won't spend its whole life at 6000rpm.

Other mods will be lightened flywheel, gas flowed heads and maybe some posh cams and eventually programmable ECU...

Any info or tips would be much appreciated...
 
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#3 ·
Hi,
If you were just going for the cc increase I would have thought all the std stuff would be fine. I am not sure how that will all perform with the list of other mods you are making. Flowing the heads and modified cams are fairly major changes and wont be cheap.
Support Ians comments about balancing. Will make the hole thing run a lot smoother and increase life expectancy.
Think AHM do the pistons on their own but the prices you looked at were the kit i.e. crank, rods and pistons. Still think they will be more than Brunswick though.
What I did was go direct to JE pistons in the US. They did me a one off special set to get the cc I wanted and it only cost about the same as Brunswicks and they were the dogs dangly bits :D .
Dont know how big you can go with std block?.

rsfruitbat
 
#5 ·
Don't know how big you can go with std block?.
That depends what you mean by "standard".
If you mean completely standard, then it is the std 1712cc.
The 2.0L engines still use the original 1.7 block, but modified, not just for the larger bore, but also because with the long throw crank moving bits start hitting things that don't move. So they need to be "modified...".
 
#4 ·
Understand that balancing is key, and all reciprocating parts need to be dynamically balanced - they are assembled on a rig and then spun up. If the pistons are a bit lighter as well as the capacity increase that will help the response and the ability to rev a bit. You can also look at having the block 'decked' (skimmed) to raise the CR a bit which would work especially well if you use a programmable ECU like an emerald. We are in the middle of building up an 8v engine and the bottom end work -balancing, core plugs, rebore, decking was done by a place in Bristol (Padfields under Temple Mead Station ask for Will) which wouldn't be too far to go. Don't know abot flowing heads etc. depends if you want a one stop shop or get the machining work done an then assemble the engine yourself. Hope it comes together well.
KR james
 
#6 ·
Sorry. What I meant was I dont know how far you can overbore a 1712cc block with 87mm pistons fitted as standard. Years ago I overbored a 1490cc with 84mm out to take the 87mm piston giving approx 1600cc.
When Alfa did the 1.7 did they give it the same allowance ? i.e. could it be overbored to 90mm giving you 1832cc, or taken even further, 91 equals 1873cc etc.

I think its the stroking that gives the problems with bits hitting bits they shouldnt do?

rsfruitbat
 
#7 ·
Years ago I overbored a 1490cc with 84mm out to take the 87mm piston giving approx 1600cc.
That is what I ran too. It took it to 1598cc, so right on the 1600 class limit.

Off of the top of my head I don't know the max overbore of the 1.7 block, but I'm sure it will go the same 3mm, which would be 1832cc.
Things will start getting close where the pistons come together in the middle at the bottom of their stroke though.

Actually, just checked AHM site and they only list upto 89mm bore
 
#8 ·
thanks for all your advice guys. My intention is to dismantle the engine and take the major component parts to an engineering shop near Stroud which is near where my parents live (www.maynardltd.co.uk). They do all the stuff I'm looking for, haven't got any details on prices yet though. I'm then going to put it all back together myself. Obviously this aint gonna be a cheap exercise but I'm going to try to keep the costs reasonable as you've got to draw the line somewhere. If the cost gets too high, you might as well just buy a faster car.....
 
#9 ·
I might suggest a wee bit of care if considering too much of a bore size increase. I understand that one of the guys in our NZ Trofeo Series had a 16v bored out to 91mm. It was a reasonably rapid engine, but suffered horrendous (terminal) cracking, after a bit of track time.

It seems you do need a little bit of meat left on the cylinder walls, and apparently 91mm was just a wee bit much for it to all hang together.
 
#11 ·
Blocks vary a bit and there is a big diference from a road to a race engine in rev limits stresses etc. A gasket set and set of cam belts can cost £100 + to bear in mind for your budget.
One word of advice is any holes in the block tape up - just had to remove the waterpump to get out a stray washer ! Heads on and timed up though. Carbs and water hoses next.
KR James
 
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