Just a quick pondering for the parts guru's if anyone wants to surmise about the following possibility.

Requirements:

• Use original block from car
• Cylinder head is free
• You require more power than an 8V can deliver easily. ~140BHP
• Avoid unnecessary expense, but OK with putting a bit of money where it is needed
• 1400cc max. capacity

Parts list:

• AFH Cylinder Head (16v and cam on tappet design which is good for RPM. Lines up with bottom end.)
• 3F/PY Block (Original for car as stipulated by rules.)

• Pistons/rod....???

Idler pulley added for 16v headCambelt with correct length/profile/widthGT Gearbox with bolt on final drive + LSD

So the make or break question is the pistons/rods. Since the AFH has combustion chamber is head the standard GT pistons are not going to work. How can this be over come?

1. There is a 3F era piston that will fit with 3F rods and give adequate compression ratio? Easiest option if available. Unlikely due to need valve cut outs.

2. Use the 16v pistons if they fit the block? What rod would be required though? The pistons have a smaller gudgeon pin than the 3F era pistons (17mm vs. 20mm)? Would the 16v rod be too long? Does a rod exist that would work off the shelf? Can you sleeve down the gudgeon pin or is this bad form? Somewhere in here I think is the cheapest option....if it can be made to work...

3.The scary options...custom pistons with 20mm gudgeon pin and an AFH style face with valve cut outs. Marginally increase CR and why there why not make them bigger bore for 1341cc? Fit them to PY/3F rods...standard or forged which ever tickle your fancy. Expensive and time consuming but will give biggest performance potential for the motor.

4.Second scary option...keep the AFH piston and get a custom forged rod instead. Use the 17mm gudgeon pin and correct length for setup. Seems like a silly way to go about it but here for completeness.

Edited 29 July, 201313 yr by Tav

Are you allowed to bore the block?

Yes, max capacity of class is 1400cc which is a little different from Germany where they are stuck with 1300cc max.

I can rebush the little end of the rods to whatever size is needed mate

Already done it on mine and Guys rods

Both From 20mm to 17mm

So that's one option for you

What length are the 3f/PY rods centre to centre and what crank are you looking to run

Edited 29 July, 201313 yr by StinkyPete

I have a spare PY G40 block and crank here. Also x2 GT short engines. So would use the crank out of one of those combinations. Would there be option for running longer stroke crank inside a 3F/PY block? ABD?

From googleygoogling I've found:

Rod Lengths

G40/GT rods are = 122mm with 20mm pins

ABD rods are = 122mm with 17mm pins

AFH rods are = 144mm with 17mm pins

Bore vs. Stroke

PY bore/stroke = 75.0 x 72.0

ABD bore/stroke = 75.0 x 78.8

AFH bore/stroke = 76.5 x 75.6

Piston Compression Heights

G40 compression height = 40mm

ABD = AEE +4mm? (AEE = 30.85mm)

AFH = 28.9mm

Possible Conclusions

• So looks like it'd need at least a 1mm over bore to take an AFH piston.
• You loose over 11mm in compression height on an AFH piston. So you need to make this back with rod length?
• A rod length of ~133mm would be required? Or is it not as simple as that?
• Using the ABD crank and rods with a PY block would get you closer...so you could deck the block down to deal with last few mm? The crank gains you 6.6mm, the pistons loose you 11mm so that leaves you with a short fall of 4.4mm? Or again is it not that simple?

Thanks for offer of bushing down : )

Edited 29 July, 201313 yr by Tav

Haven't you also got to watch the pulleys

Would you need to use an afh crank and crank pulley to match the cam pulley profiles

Or would the afh crank pulley fit the 3f/PY crank

What about the waterpump too as isn't that the belt tensioner on early engines

Water pump can be retained...or ditched for electric I guess. Wonder of AFH crank fits...or if that's any help at all. The main thing is the pistons/rods.

Did find a German guy who'll do 78mm pistons on whatever rod you want but that sounds a bit hardcore!

Can you fit an AFH crank in a 3F block? (I don't see why not, you may need to machine the internals for the extra throw length but it should be the right dimensions), use the shorter rods from the ABD and get some first oversize 76.75 AFH pistons? This would give you 1399cc (76.75*75.6)

AFH block is taller than 3F. By how much I'm not sure but it can be estimated by the height difference between the two mounting holes for the alternator bracket and the top of the block, will give you some idea of piston height at TDC with this setup

Here's an AFH with a mk3 engine mount

A 3F is virtually flush. You loose 11mm of height by fitting the ABD rods, how much taller do you think that looks? (you could also put a thick headgasket on there from the 1.6 ABU, if it's not far out)

Good photo. I wonder if a kind soul with an afh conversion could measure it.

The AFH block is taller in that case?

Edited 29 July, 201313 yr by Tav

Just measured mine for you and it comes in at around 12mm. Thats an avy block however but apparently there the same casting?

3F (or similar) I found on google

Gaz I consider myself a dab hand on google...and I failed to get that photo. Hats off to you sir!

I guess logically the extra height has to be in the deck height...it'd be the easiest way for them to cast it.

Def. rules out using an AFH block as they are physically different and the rules state "externally identifiable as a block fitted to that model of car"

Edited 29 July, 201313 yr by Tav

So could you not run full ABD internals in a PY block with the 16v head

Just guesstimating stuff there needs actual proper working out

The belt and pulleys would still need sorting to get them all matching to the afh belt and cam pulleys

The pistons will probably still need skimming even for a turbo! But you can use a 3F head gasket and the valves will clear it - i used an ABD gasket with the AFH head.

If you really need to use the 3F block then that's the problem and it's just about how far you go back along the line. For 1300cc you could use AFH pistons and get your rods adapted to hold them. Then deck the block and/or sort the gasket choice to suit.

That requires various engineering issues just for 1300cc so you'd be wise to look at other ideas. The AFH crank gives you a longer stroke that will take you to 1390cc but you'll need the AFH rods because the GT rods won't fit on the AFH crank unless you skim the life out of it and subsequently remove all the hard stuff, turning it to cheese.. afaik.

So you want an AFH bottom end, but you want to squeeze it into a 3F block, which means the block will need all hell cut out of it. Which i'm sure is perfectly viable.

Another option, viable IMDHO is to skim the end face off an AFH block until the engine code is erased, then etch the 3F code in it's place!

The pistons will probably still need skimming even for a turbo! But you can use a 3F head gasket and the valves will clear it - i used an ABD gasket with the AFH head.

It'd be N/A. If it were forced induction then 8 valve isn't such a problem. If someone rocks up with mega-power then my gearbox will stop me playing.

If you really need to use the 3F block then that's the problem and it's just about how far you go back along the line. For 1300cc you could use AFH pistons and get your rods adapted to hold them. Then deck the block and/or sort the gasket choice to suit.

That requires various engineering issues just for 1300cc so you'd be wise to look at other ideas. The AFH crank gives you a longer stroke that will take you to 1390cc but you'll need the AFH rods because the GT rods won't fit on the AFH crank unless you skim the life out of it and subsequently remove all the hard stuff, turning it to cheese.. afaik.

So you want an AFH bottom end, but you want to squeeze it into a 3F block, which means the block will need all hell cut out of it. Which i'm sure is perfectly viable.

Another option, viable IMDHO is to skim the end face off an AFH block until the engine code is erased, then etch the 3F code in it's place!

I take it from that you believe the diameter of the crank where the conrod joins is bigger on the AFH than on an 8 valve?

Cutting the hell out of the block, just to clear the crank? Do-able perhaps...

Skimming the face is amusing...other than the deck height difference I'd think there must be other external differences on the castings?

So could you not run full ABD internals in a PY block with the 16v head

Just guesstimating stuff there needs actual proper working out

The belt and pulleys would still need sorting to get them all matching to the afh belt and cam pulleys

Perhaps...with some piston machining? Then isn't that just same as putting AFH head on ABD block?

Probably I'm not too clued up on the 8v blocks mate

I just thought you wanted to use a PY block for strength etc

1W internals might be worth investigating? They'll go in a 3F block, 1398cc, and 22:1CR I think with a flat head - not sure what you could get to with a played with AFH head. If a thick HG and opened up combustion chambers in the AFH head got you down to 12:1CR or so it could be interesting.

Other downer on using that setup is stoke > bore, i.e. not so keen on revving. Could be a deal breaker as we're talking race engine, and rpm required to make power at expense of wide torque band.

Could keep 3F block, crank and rods, and overbore to 77mm giving 1341cc - then custom pistons might give you a usable CR with a heavily skimmed head, but you'd need to get some parts and do some measuring.

Mikey's suggestion to investigate re-packaging a full AFH into a 3F also warrants further investigation.

How switched on are the governing body (and competitors) for the class you're racing in? May get away with a cosmetically-tweaked AFH?

Lol coming from a Motorsport background essentially suggesting cheating is irritating me.

Also, if you're grafting a head on can you not use a 20v head? :)

Gaz I consider myself a dab hand on google...and I failed to get that photo. Hats off to you sir!

I guess logically the extra height has to be in the deck height...it'd be the easiest way for them to cast it.

Def. rules out using an AFH block as they are physically different and the rules state "externally identifiable as a block fitted to that model of car"

How would they know that it was physically different unless they had both blocks next to each other and knew what they were looking for? On a fully built up and fitted engine are they really going to be able to tell that that was a block that wasn't fitted to the car originally? Especially if you add the third bolt hole by getting a small section of a 86c engine welded to the afh block

sure I read a similar thread on club GTI time ago that mentioned an early 8v engine code with the combustion chamber in the head and flat pistons. I'll put my google foo in to action...

Lol coming from a Motorsport background essentially suggesting cheating is irritating me.

Also, if you're grafting a head on can you not use a 20v head? :)

Its only cheating if you get caught

a fermented thread http://www.clubgti.com/showthread.php?2349...o&styleid=9

1W internals might be worth investigating? They'll go in a 3F block, 1398cc, and 22:1CR I think with a flat head - not sure what you could get to with a played with AFH head. If a thick HG and opened up combustion chambers in the AFH head got you down to 12:1CR or so it could be interesting.

Other downer on using that setup is stoke > bore, i.e. not so keen on revving. Could be a deal breaker as we're talking race engine, and rpm required to make power at expense of wide torque band.

Could keep 3F block, crank and rods, and overbore to 77mm giving 1341cc - then custom pistons might give you a usable CR with a heavily skimmed head, but you'd need to get some parts and do some measuring.

Mikey's suggestion to investigate re-packaging a full AFH into a 3F also warrants further investigation.

How switched on are the governing body (and competitors) for the class you're racing in? May get away with a cosmetically-tweaked AFH?

I thought briefly about 1W but quite difficult to get and not sure about pistons being suitable? I guess the crank has a longer throw? Same bore? But then likely to have big heavy pistons. I really need to learn more about what makes a 1W different.

I have found germans running 78mm Andy and who sell head gasket to suit...might be taking the piss though! But without the issues of boost on a G40 maybe the block would be up to it. If getting custom pistons anyway +1mm won't be any additional cost.

Would be rev limited by keeping head hydraulic...my gut tells me there wouldn't be cash for converting to solid lifters. Also the crank may be a limiting factor, not sure how well they take 8k+

Gaz I consider myself a dab hand on google...and I failed to get that photo. Hats off to you sir!

I guess logically the extra height has to be in the deck height...it'd be the easiest way for them to cast it.

Def. rules out using an AFH block as they are physically different and the rules state "externally identifiable as a block fitted to that model of car"

How would they know that it was physically different unless they had both blocks next to each other and knew what they were looking for? On a fully built up and fitted engine are they really going to be able to tell that that was a block that wasn't fitted to the car originally? Especially if you add the third bolt hole by getting a small section of a 86c engine welded to the afh block

sure I read a similar thread on club GTI time ago that mentioned an early 8v engine code with the combustion chamber in the head and flat pistons. I'll put my google foo in to action...

HH I think for pistons McLovin? Maybe wrong? Would still need machined for the valves I'd think. Would be intersting to know how the combustion volumes compared between the old mech heads and the AFH.

I think I could slap a AFH in and know one would know. But it's the principle of the thing, should like to do well whilst being within the rules. If it ended up +10cc over 1400 I wouldn't be so worried.

It's not so much about the difference between 8v and 16v engines. It's the difference between engines of two different generations - a 1.4 AEX engine from a 6n, for example, can be converted to 16v with no engineering work whatsoever, because it's from the same pattern series/family.

The 3F is a previous generation engine along with all the 1043/1272cc blocks, and the 1391cc ABD block.

So if you need a wider crankcase and wanna get away with using another block, you'd use an ABD because it's of the 3F series/family. I don't know how it deals with the longer stroke as far as crown/deck meet is concerned (shorter rods or higher deck, i suspect the latter).

As for appearance, the later generation engines have just one core plug in the front of the block - earlier ones have like four. This will be the biggest giveaway. Lots of other visual differences too though, such as the third anchorage point for the engine mount to deal with, very obvious one is the extra gearbox mount on the front covering the flywheel which is merely covered by the engine plate on later engines, bolt-on steel relay coolant pipe from the water pump instead of plug-in plastic (and the pump has slotted mounts as it acts as a tensioner), etc etc on the earlier generation engines.

I would be able to tell it was a later engine with my eyes blindfolded and boxing gloves on basically, so chances are that someone who looks for this sort of thing will suspect something..

Yeah so anyway, given that the main crank bearings are the same size and the earlier AFH's oil pump is a direct replacement for the GT one, and will even accept the shorter GT funnel if you want the shallower sump (i don't recommend this, you should instead convert a sump so it holds more and is baffled), and if the GT block will overbore to 76.5mm safely, then putting full AFH internals into the original bare 3F engine block is the honest way forward. Though i think the rules need to be taken in context, meaning don't put a V8 in there, meaning an ABD block just might sort your clearance and deck out without breaking the rules..? But then i really don't know jack about all that.

GT block should take 76.5mm as G40 boys manage 77mm with the forged pistons quite often. No boost to worry about nor high mileages. Avoids needing fancy (expensive) pistons.

The rules are tight enough that you can't use a B18 Honda block in a car that came with a B16 as the extra height is a breech of the rules, even though the engines look identical. If the scrutineer didn't notice it a competitor or punter might.

It's not F1 where they weigh you to see if you've had a poo, but the rules are there and should be respected.

From everyones input it looks like a 3F/AFH hybrid or ABD/AFH hybrid might be worth exploring. I did see a thread today where the oil pumps were swapped out as you suggested mikey.

Chances of finding and AFH up here....slim...