maxiboy
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Bigger bore 3.2

Post by maxiboy »

hiya all new here been reading for a few weeks though

thought I would post for some advice if its available please

I,m needing advice and photo's if possible on over boring the 3.0 block to except 98mm liners..

any advice on what liners to use..some man truck and john deer tractor are correct in diameter

also thinking honda vtr pistons as these seem close to ideal.. lightweight proven and cheap enough to buy 6

so maybe using bmw rods ( not sure which though ) though I assume this means grinding the alfa crank a lot smaller on the big ends.. is this safe and been done before

is there a better rod to use .. thinking of upgrading to H section rods anyway..

also thinking of a custom crank but standard sizes unless the big ends need altering..

any other advice you can supply me on this conversion..

thanks in advance
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MD
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Re: Bigger bore 3.2

Post by MD »

Before people give you some advice, it might be helpful to tell them what the engine is for.
Street or race. What sort of revs you intend to do with it. Power objectives etc and why you dont just use an original Alfa motor of 3.2 litre capacity to start with.
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kevin
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Re: Bigger bore 3.2

Post by kevin »

What country do you live in ?
Is it not cheaper just to find a gta crank then you don't have to worry about getting special head gaskets made . Come to think of it you can buy a complete 3.2 gta motor in uk for same price it cost for head gaskets and welding in the water channels in the head so they don't interfere with the edge of gasket .
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Re: Bigger bore 3.2

Post by 75evo »

Kev is correct, UK 3.2 engines are VERY reasonably priced! I sort of wish I lived in UK....

Custom race steel cranks are VERY expensive.

We don't know your budget. But a 3.0 24V can be had next to nothing. You could fit a rotrex and get the power equivalent to a 3.7.
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Re: Bigger bore 3.2

Post by maxiboy »

hello

thanks for the questions

I do live in the Uk and run a 3.2 156 gta..

just fancied a bit more power for road use only..

instead of stripping the current engine thought I would build a spare dyno it then add it to the car with uprated clutch etc..

I have a spare 3.0 litre engine and priced a new 3.2 crank ... haven't yet looked for a secondhand item. think I can get a crank made for around a thousand so compared to buying a new spare not too much in it

was thinking 98mm bore on the 3.2 bottom end .. was hoping 98mm avoided welding the water ways.. in the head..

If its not viable might just rebuild the 3.0 litre as 3.2 and do the cams and raise compression..

just thought a 98mm big block might be more fun really as I love building engines..

I know turbo super charger is easier but don't want one. last two cars have been 500bhp turbo monsters and want some thing N/A just maybe with a bit more grunt..

can get gaskets machining etc done locally from a mate so was thinking of squeezing 98mm liners in with a 3.2 crank

3.0 litre 98mm bore would be a better option for a short stroke turbo configuration except the revs are limited on these engines unless going solid lifters I read 7600rpm limit on hydraulics

maybe a 3.6 with cat cams, new springs, lighter valves uprated bolts and redesigned intake and exhaust manifolds etc would be possible

opinions welcome
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Re: Bigger bore 3.2

Post by 75evo »

If you want more power then probably the best thing, is up the compression to 11-11.5 by skimming the heads. And talk to Jim K about his new cams which he posted the profile on one of the topics. Then custom make a set of equal length headers and get Alfatune or AHM to map it.

I'm pretty sure you will match an E46 M3.
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Re: Bigger bore 3.2

Post by kevin »

They have been a number of engine builders who have spent a fortune on school fees . Problem areas have been getting good quality liners / barrels that don't distort when machining and also lend themselves to the expansion rates of the pistons . If you get this wrong and along with your honing patterns you will consume huge amounts of oil and piston slap etc . Engine builders will not give out this info on material of liners but will tell you they use Ross / JE or even much better Woessner pistons .
You will have to extract the studs which sometimes creates problems but if you don't make perfect jig for the block it can also distort when machining .
BMW rods have been used in the past but guys normally do this when the crank is stuffed to fit oversize Alfa bearings and the cut the journal down more for the bm rods . Crank gets treated , hardened etc and I do know of an engine that's done over 100000 km with bm rods .

Here is an interesting build by Auto lusso and you can read they have done this a few times due to failures in the past ie school fees .
http://www.alfaowner.com/Forum/alfa-gta ... anuts.html

I think your biggest problem is going to find the correct liners to start the process .
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Re: Bigger bore 3.2

Post by maxiboy »

yes I can see the levels of engineering going into just installing the liners is massive..

I was oping there would be a cost effective way of going 98mm not 101mm that avoided the water way issue and allowed the use of the bike pistons..

looking at the effort evolved doesn't scare me but the fact that after the effort it might be a miserable failure does.. lol

maybe I will just get some 93mm high compression pistons and high lift cams and go from there...

thanks all
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Re: Bigger bore 3.2

Post by maxiboy »

on a second read I will give it a go lol..

will see what bore I can achieve without head mods

the £2000 jig just holds the block straight and the issues where with the honing of the liners not flex etc.. I'm used to running total seal rings on all my rebuilt engines.
Most are built using wossner too

I always hone my block using a custom made deck plate and with the mains torqued up..

done bigger mods before with custom ladder blocks etc

Now i,m not saying it will work but once I have my 3.0 litre apart I will explore the option further and see what i can achieve as the fun for me is trying..

if it fails I will refit the 3.2 lmao with head and cams from this engine...

he who dares ....... ( not sure yet )
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Re: Bigger bore 3.2

Post by 75evo »

That Autolusso 3.8, if it can be had for UKP10,000 + 3.2 engine, it would be a steal!
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Re: Bigger bore 3.2

Post by kevin »

The autolusso conversion is more like £15000 plus engine . As you said you won't need to do any head welding with the 98mm bore pistons . Personally I always chose a max of100mm for my conversions and this block work was very successfully done for me by Dawie six years ago in SA .
There are a lot of 3.3 GTV running in SA right from the late eighties with the 3.0 crank but these were 12v . I had 3.3 24 v that revved like a bike so I would pursue it if you want yo have fun .
Just post the pics so we can enjoy the journey . Oh did you mention which car it's going into .
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Re: Bigger bore 3.2

Post by 75evo »

For the level of workmanship Autolusso provides, I would say expensive but well worth the money. If I had a GTA there I would do it.

Coupled with JK's cams, and supersprint headers and custom plenum, we're looking at 370+ bhp. That's about the same as the MK1 996 GT3.
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Re: Bigger bore 3.2

Post by Mats »

This will be VERY expensive and will come with exactly ZERO warranty...

Why not a radial supercharger. More power and a lot less complicated/expensive.
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maxiboy
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Re: Bigger bore 3.2

Post by maxiboy »

Yeah the car its going in is a 156gta..

not doing a cheaper easier supercharger or turbo as I,ve done loads..

including over 500bhp in a clio williams with maxi kit my last car..

this time N/A all the way.. I think with a little luck I can keep costs down

A lot less than 15,000k hopefully..

If I had that money I would just buy a drive in drive out conversion from ned.. or go the whole hog like there latest project a bare shell dipped in an acid tank to 3.8 q4 hill climb car..

I just want a little more for road use nothing extreme.

98mm liners are available of the shelf from a range of diesel engines so should be strong enough with some work.. some 98mm pistons are available though this leaves a rod issue and deck heights are different so may go steel alfa rods and custom made pistons wont know till I get a little further along..

thanks for all your help .. its really just a project to keep me out the pub and spend my beer tokens elsewhere...
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Re: Bigger bore 3.2

Post by 75evo »

What we can see is the most vital part is the block machining. Either Autolusso or AHM can do it. AHM did one for a Japanese 147 3.8 GTA

https://www.youtube.com/watch?v=C__9JQHNNWc

So if you get the machining, honing and ring gapped right, by the correct shops, then the next thing is to buy the custom head gasket from a reputable source. Besides these, you can DIY most of the other steps.

BTW, did you check out Autolusso's Wizard line of exhaust for the GTA? Wicked.
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