some help.....

[trickymex]

Hi peeps

Im new to audi S2's but not to performance cars

I am looking for a S2 avant as a little project car for myself, i build race engines and i will not be able to leave this one alone so what i need to know are some of the differences between the 5 pots available

I think it goes

AAN
3B
ABY

and some diesel ones

What ones are best and what are the differences?

are all the stroke and bores the same, and are all the valve sizes the same?

and what is needed for a stroker version

also if anyone knows of an avant for sale with a blown engine i would be interested

cheers in advance

Ricky

[terrybullwon]

What engines do you build Ricky?

Welcome BTW...

If you are going to build one from scratch, any 2.2 turbo block will do. But watch out for heads with hair line cracks in the chambers.

[Fat Audi 80]

This is well documented, so I would suggest you do a quick search....

Basics:

3B = Distributor Ignition, paper head gasket, weaker bottom end
ABY, AAN = Coil per cylinder, stronger bottom end, metal head gasket
ADU = Same as above but with larger turbo, intercooler, revised IM and EM + bigger injectors and revised Mapping. (RS2)

"Stokers" using the diesel block etc are a whole different ball, game check out Jamo's project thread....

The bore, stroke etc I believe are all the same. Figures easily found with a search.

HTH and

Cheers,

Steve.

[trickymex]

Thanks guys

I have done some searching but im strugleing to find the info needed, i will keep trying

Terry, I was trained by Cosworth F1 engine builder and i used to work for burton power working mostly on Ford engine's, BDA's Cosworths and such like

I left there and i have built a wide range of road and race engine's since

I have more recently been working on Fiat coupes with there 5 cylinder engine, the sound is very nice so i thought i would have a look at an S2 as they are 4WD instead of the fiats FWD

I dont want a mental BHP one as i have a R32 GTR with 662BHP for scaring myself but i thought a nice 350-400bhp big capacity S2 would be nice for cruising around in, instead of my range rover, you see my everyday car needs to be a little family orientated and i think an S2 could be a good choice

So if anyone wants to swap for my range rover get in touch

[Jamo]

Stock = 86.4 crank x 81 bore
Stroker cranks = 92.8 or 95.5

A lot of people come over here asking for crazy rebuild spec for the s2

It's simple 400 bhp can be had with a turbo / manifold / exhaust and remap and other various sundries.

RS2 turbo route will get you 380, 3071r will give you 450, 2871r will give you 420.

There is no magic secret anything sub 450 bhp is easily obtainable.

[trickymex]

Cheers for the info

I got the impression that 400ish bhp was very easy but im looking for more than that

I want a very torquey low lag setup, making peak torque very low down, but untill i know this engine i do not know what to expect

I have seen on here people fitting 2871's and there not boosting till about 3750-4000 rpm thats to late for me

I honestly dont know why you would be suffering from that sort of lag on this engine

I have used the same turbo on the fiat 5 cylinder engines in .86 and 64 housing varaties

With the .64 housing and 2000cc we were hitting peak boost in 3rd gear by 2500 rpm and with the .86 housing by about 3000rpm

These are both running nearly 2 bar of boost

So im sure i getting some info thats not quite correct or im getting mixed up so any help would be greatly appreciated

cheers

[Jamo]

I think you may have the wrong dyno plots

2871 & 3071 will have you full boosting way lower than 4000rpm more like 3000-3500rpm RS2 about 3500-3600

This can be helped with a reverse inlet manifold

[trickymex]

Cheers again Jamo,

You seem to have a good grasp of these engines

In your opinion what setup would you go for if you wanted say 400bhp but torquy as possible and the least amount of lag

You mention the stroker cranks having 92.8 and 95.5mm stroke, thats a massive stroke and the piston velocity would be very high, do people in general that have gone the stroker route limit the RPM somewhat??

Also what is the standard rod length, im trying to work out the rod to stroke ratio

Cheers

Ricky

[Sonic]

Jamo is in the limelight at the moment because his stroker project is about to come into fruition

Besides strokers, for >400bhp id say 2871, if you're happy with more torque but less horses then its RS2 (k24 7200) which is cheaper.

[Ross]

I've run a GT3071R on a 3B engine and had 430hp, hitting 1bar at 3,000rpm and 2bar just after 3,500rpm. That was seen as pretty good although i was seeing a little big of surging, and perhaps needed to limit max boost till 3,800 or do some headwork to help.

i think the GT2871R is what you're looking at, surging is the concern but as s2central.net (aka Paul) has recently found it seems to not be a problem when mapping the car on the open road. Full boost was more like 3,000rpm if I recall, peak power around 420hp.

[Jamo]

Cheers again Jamo,

You seem to have a good grasp of these engines

In your opinion what setup would you go for if you wanted say 400bhp but torquy as possible and the least amount of lag

You mention the stroker cranks having 92.8 and 95.5mm stroke, thats a massive stroke and the piston velocity would be very high, do people in general that have gone the stroker route limit the RPM somewhat??

Also what is the standard rod length, im trying to work out the rod to stroke ratio

Cheers

Ricky

RS2 route hard to beat for torque it's only 380 bhp but S2avant has done a 4 sec 0-60 with a 12 second quarter mile.

Stock rod ratio is 1.66 IIRC

Easiest Stroker torque route is the 92.8 in the 220mm block

True stroker is the 236mm diesel block and 95.5mm

Stock RPM limit of 7300 is fine for both stroker. You'll never rev to that anyhow

To be honest I'm covering old ground there are a lot of threads with this and S2central and co have spread sheet generators where you can mess with the bore and stroke to see the effect of the torque line.

Strap yourself in and have a good search

[trickymex]

Thanks for all the info

I am searching at the moment but strugeling

Is there anywhere i can just get the measurements for the different engines

I would like

stroke for all the cranks

the bore seems to be 81mm std on all of them

rod length for all enigines

block height for all the differents blocks

and what the differences are between the blocks are

Also i have read a fair bit on cams on this site but actual figures, like duration and lift seem scarce

Any differences in heads or valve train between them all??

I have some race engine simulation software and these figures would be very helpfull

Regards

Ricky

[S2central.net]

Welcome tricky... you are 5 posts in... calm down dear - much of what you seek is on here. Can be frustrating searching for it all - there just isn't one thread that nails all these topics for engine build projects. Things like camshaft topics are often a bit contencious - as you can imagine.

The 3B, AAN, ABY, ADU blocks are for all intents and purposes identical. The 3B's and early AANs left the factory with softer bearings than the ABY and ADU but they'll be replaced on any serious build. The 3B runs a single mass flywheel which can be fitted to the other blocks. The 3B has some variation on drillings for timing belt tensioner and water pump but nothing wildly different. They all run the same crank for 2226cc - in fact I'm sure its the same crank as an old KV engine - 2226cc non turbo. Amazing !

You'll need to search the stroker threads for more crank and conrod info of course - I can't keep up with all the options on that.

For a ~400bhp goal - I'd say its down to 2871 or RS2 depending on taste... But don't rule out units from CompTurbo which are favoured by some of the big power Scandic tuners on here.

The 20VT heads are all identical - in fact a 7A or NM head can be modified for turbo duty as well by the addition of a different water rails - and sodium filled EX valves which are standard on the turbo applications. Depending on budget you can go solid lifters as well - guessing not on this build if is primary duty is daily duties.

Seek out the 'Turbology' threads and some spreadsheet calculators which have successfully estimated things pretty well - it does injector selection as well as torque & power estimates. Your professional software is likely going to do a somewhat more thorough job, but the spreadsheet method has served us well - if you can read a compressor map.

[trickymex]

Thanks Paul

I am now going to do some investigations and try to find one for sale

Ricky

[macspring]

My low tech advice is,

from reading the thread so far is to buy an ABY Avant and start from there.

Depending on your budget for the project, also err on the side of a slightly smaller turbo rather than a slightly bigger one.

The reasoning behind this everytime you drive it you'll want to spool up a.s.a.p. after each and every gear change, but you won't be able to red line it in every gear.

Does this make sense? Torque and early spool up, more important that max bhp and it all happening after 4,000rpm only.

Consider changing the rods so that it can be mapped for maximum torque and still have peace of mind. Change the dual mass ABY flywheel to a 3B single mass flywheel which is lighter.

Again depending on the budget, consult with one or of the decent turbo companies on hybrids that would be similar to a 2871, but might be slightly better, but corresponding dearer, you pays your money and takes your...... and all that.

Change the ARB, stick with standard springs and fresh shocks (Konis).

Stick with 8 x 17 rims with 225/45/17 tyres.

Change the front brakes to Porsche calipers with the correct braket and 323mm discs. Others can fill in the exact details?

Change the rear calipers to a second hand set of alloy ones off any Mk4 Golf or similar as opposed to the originals on which the hand-brake tends to seize.

Others may suggest bigger back brakes, but try these for starters and you can always upgrade later, but only if you feel the need.

Ultimote.de

Having said all of the above, it's just my own opinion, but hopefully it will assit you in making up your own mind as to what to do with your car?

I suppose it's really what I'd do now, knowing what I now know if I was starting out from your position again with a daily driver.

One last thing to keep in mind is to plan it so that it is all done at once, (in so far as it's possible), so the car is not off the road for months on end? BTDT.

Keep us all posted on your progress?



Kind regards.