ALFAGTV6.COM

[Steve R]

Prompted by a conversation with Kevin on Saturday at Alex Jupe's open day I thought I'd add some photo's and write up my own GTV6 conversion. I tend to visit this site often, but generally lurking rather than commenting - much like many others I'm sure.

I've learned a lot from people and comments on this site to put into practice with my own car and quietly concentrated on getting on with the work myself during occasional evenings and weekends over the past couple of years.

Car work isn't my day job, but I enjoy doing it as a hobby as it's very different from my desk based normal work. Basically I'm just a home mechanic who enjoys making stuff, an overall summary of the work would be as follows:

• 3.0 24v Alfa 164 based engine
• Eaton M90 supercharger (OEM Jaguar XJR, Aston DB7)
• hi capacity charge-cooler welded to modified fwd GTV 916 plenum
• Charge cooler radiator is main engine radiator from Fiat Cinquecento
• Bosch charge cooler water pump
• 7.5kg flywheel (factory standard Alfa 164 auto version minus torque converter) with adaptor to accept GTV6 guibo and propshaft splines
• 147 / 156 GTA spec large inlet runners
• Alfa 75 power steering
• ECU = home made Megasquirt system running fuel and ignition
• 380cc/min Fuel injectors
• Wasted spark set up using 164 COP coils
• Re-cored GTV6 radiator with 156 v6 fans and modified shroud
• Alfa 166 stainless steel manifolds modified for 116 chassis, stainless twin 2.25” into 3” straight through full exhaust system from manifold flanges back
• 120 Amp alternator from Alfa 164
• Uprated dip beam units to replace the woeful Carello candles
• Lots of home made bracketry etc for everything!
• Alfa 75 3.0 transaxle with LSD & strengthened mounts
• Short shift gear linkage
• Front brakes = 305mm Alfa 147 GTA disks, Porsche Brembo monoblock 4 piston calipers
• Rear brakes = Alfa SZ vented disks, standard GTV6 calipers with spacers.
• Front suspension = standard GTV6 torsion bars, lowered, Koni shocks converted to coilover, 105 style caster arms, Harvey Bailey 28mm anti-roll bar
• Rear suspension = Harvey Bailey lowering springs, Koni shocks

Photo of nearly complete under bonnet:

[Steve R]

The car runs about 7.5psi max boost, 50kpa over ambient on the MAP sensor, making 4 psi from 1000rpm tickover and the full half bar by 2000rpm onwards. Exact power and torque are as yet untested, once I'm happy with everything I aim to dyno this autumn and I'll post the result, calculations indicate the motor should be over 300hp but I'll have to wait and see. Power feels very strong on the road and tractability wise it pulls the long 75 3.0 gearing easily from 1000rpm.

Special thanks to sources of info from Jim K's v6 book, plus Greg Gordon's supercharger book, both were extremely useful for research prior to and during my build. I would go so far as to say don't start such a project without researching those sources first.

The engine is a 164 3.0 24v motor modified to fit the 116 chassis pretty much in the same way documented elsewhere on this site, those write ups were invaluable so thanks to all who documented. I won't reiterate what others have already shown and said, but I'll mention a couple of areas I found more tricky with a few comments to try and clarify for others contemplating similar projects.

For instance the oil pump swap required the pump impeller being moved further along it's shaft. I used a wooden block with a hole to fit the shaft, then heated the impeller and very carefully drifted it along the 9 or 10mm to fit correctly. A few repeats and all was well, although I was nervous of deforming the impeller - hence lots of care.

Making the GTV6 sump fit the 164 block required some modifications where you know a badly placed drill could wreck the block! Steady hand and careful marking out required.

I'll show various photos and descriptions of the area's where I did my own thing :- supercharger mounting bracketry, exhaust manifold modifications and exhaust set up, plus the chargecooler / plenum arrangement. Maybe the front brakes too.

If there's other things you'd specifically like to see just ask.

[Steve R]

For adequate cooling I had the GTV6 radiator re-cored as I've read they are rather oversized in the standard car. Howewer, not feeling the standard fans were up to the increased demands of water cooled chargecooler plus motor I used the more powerful and efficient twin fan arrangement from an Alfa 156. I cut the mounting legs off the 156 shroud and just re welded them to fit the GTV6 mounts, repainted, then added the GTV6 wiring connectors.

These fans move much more air and make less noise.

I wanted maximum chargecooler efficiency thus needing it to receive the coldest water possible, to that effect it has it's own radiator which is actually the main engine radiator from a 40Kw Fiat Cinquecento ! This fits neatly inbetween the normal GTV6 radiator and the front grill, attached to the mounting lugs that would hold the A/C rad if fitted, the photo's show horizontal mounting bars, but I cut then off before fitting just leaving the vertical mounting legs. This fits snugly up against the main radiator with some aluminium and foam sealing to ensure the air goes through rather than around the core.

A Bosch chargecooler pump circulates the water, these are OEM for various forced induction Fords, Jaguar, Renault etc. This water circuit is entirely separate from the main coolant with it's own small header tank.

After a drive the chargecooler body remains cool to the touch, i don't have a measurement but the output hose of this add on radiator runs colder than the temperature of my hand. Ambient temp in a UK summer is only about 20c though!

[Steve R]

Early on in the build I made a few decisions that influenced everything else:

1- Needed the layout to be as compact as possible as there is not much room in a GTV6 engine compartment, a 75 would be much easier to install.
2- Intended to use the Alfa 164 factory 7 rib poly-v auxiliary belt arrangement to drive everything, partly to save space, partly as it's aesthetically pleasing
3- I really like the idea of one single part performing more than one function if possible as this is pleasing from an engineering perspective.

The supercharger itself is a second hand unit from a Jaguar XJR 4.0, it's an Eaton M90 unit and slightly on the large size for the likely power output. Greg Gordon's book suggests an M62 would be a better size match, but to be honest I couldn't find one easily, then a short nose M90 cropped up in good condition at a good price.

I know second hand parts are frowned upon, but this unit doesn't have any apparent slack in the motion nor wear marks, or noise, so I just replaced the internal coupling with an uprated part and changed the oil. Word of advice - supercharger oil STINKS! You really don't want this stuff on your clothes or skin as you'll smell it forever!

I cut the massive cast lugs off the supercharger casing as they were so large it wouldn't fit, instead I've used the 8 widely spaced mounting holes for the factory inlet and outlet as I feel they are more than adequate to hold it in place.

The bracket that holds the supercharger actually combines 7 functions into one piece of work (see point 3!) :- Holds the weight, provides exact location and orientation against the engine, mounting point for an adjustable belt idler pulley, compressed air output pipe, cold air inlet transition from round throttle to rectangular SC inlet, bypass valve hose connector and throttle mounting flange. the whole thing bolts to the engine with just 4 bolts and somewhat surprisingly it can be put into and removed from the car without much trouble at all.

Photo's will give a better idea:

[Steve R]

Some more photo's of the bracket from above, plus the SC itself in situ.

No complex CAD/CAM activities were harmed in the making of this bracket, this was just a combination of careful measuring, cardboard and thin board templates and some iterative work to get it in the right place.

You might spot that the inner wing had to be "massaged" with a hammer in order to ensure adequate clearance, I only "adjusted" it by about 10mm or so and I took these photo's before repainting over the hammer marks.

You can see the heat wrapped exhaust manifolds in those shots too, I'll show some photo's of those in the raw later. The heat wrap is simply to keep under bonnet temperatures down and keep the heat away from both the starter motor and supercharger.

Yes, the SC really is mounted that close to the head!

[Steve R]

No factory Alfa's have exhaust manifolds that will fit a 24v motor into the rear drive chassis, you'll either have to make some from scratch, or modify a set of 24v manifolds to fit.

I tried to modify a pair, but it turns out I'm not skilled enough to produce an airtight stainless weld! For a second attempt I bought a pair of Alfa 166 v6 manifolds from ebay and made a jig to hold the flanges in the right place and cut and bent the pipes to the right orientation, I have kept the jigs if anyone local wants to borrow them. I took all this to a local specialist welding shop where they welded it all together and leak tested, they did a great job.

Good enough in fact that I asked them to weld the chargecooler to the plenum and they also made a new water pump pulley from scratch out of aluminium billet.

Elite fabrication and welding in Poole Dorset if anyone is interested, ask for Andy.

Exhaust manifold pictures:

[Steve R]

Choosing to use the 7rib pulley for everything meant I needed to alter the belt routing. Mostly this wasn't too tricky, except that the water pump pulley and crank pulley are very close together such that I couldn't get two thicknesses of belt in the gap without them touching. I had Elite make a custom pulley that was 3mm smaller in overall diameter.

My observation is that water pump bearings and subsequently water seals on V6's tend to fail as the side loading on the bearing is high because of running the belt too tight to stop the other high power items from slipping (alternator, ps, a/c). Therefore I managed to run my drive belt onto the water pump pulley on two opposite sides that both drive it so even though the belt is correctly rather tight, there is no side loading on its bearings at all.

The tension is provided by an automatic factory belt tensioner from a Ford diesel transit van!

Measured the belt run with a steel tape measure and went to the local parts vendors - getting the correct length was awkward as it turns out no UK vehicles using the exact size needed (bigger or smaller no problem!). I ordered the right length of 8 rib belt online from summit racing in USA and very carefully sliced one rib off with a craft knife. Of course I also bought a spare!! I had to slightly shim the idler nearest the SC to make the belt run completely true, it runs great with no slippage or belt wander.

Couple of photo's showing the belt routing mocked up with everything in place, in these shots the water pump pulley wasn't yet attached, but you can clearly see it gets two power inputs, from both above and below.

[Grdi]

Nice!

what bhp you're expecting?
I hope propshaft/gearbox will handle this.
75 3.0 gearbox...you didn't look for the 1.8turbo?

OEM propshaft and gearbox are the weakest links always when 250+ bhp on race transaxle
if will be for weekend crousing and rare track day will be ok although I would fit 1.8t gearbox on this setup


good luck!

[SydneyJules]

Nice work, mate!

[kevin]

Even better to see this car in the metal . It really does sound the business . Do you have any pics of your flywheel set up as I think you mentioned you used the 164 type ?

[Steve R]

Hi guys,
Grdi - the transaxle is the 3.0 75 box as I understand that has the largest pinion of the variants sold in the UK. 1.8t was never imported officially to this country so I must admit I didn't bother trying to source one figuring the freight costs would be high for bringing something that heavy from another country. If someone happens to have one for a reasonable price I'd be interested in picking it up for a spare though.

You're correct about the proposed usage, this is a road car that will see the occasional track day, so stresses should be much less that competitive use.

Cheers Kevin, the flywheel adaptor idea was from Daniel on this site, mine looks exactly like the one shown in the second photo on this thread: viewtopic.php?f=21&t=2781 I say exactly because I PM'd Daniel who made another identical adaptor and sent it to me ! As this method doesn't include any extra spacing for the 24v block to flywheel I also had to cut 4mm off the rear lip of the GTV6 sump and alter the starter motor mounting position a little too.

If you still read this site - thank you Daniel, it works a treat.

The crank, front pulley and flywheel are therefore absolutely stock Alfa components from an automatic 164, once the bulky 9kg torque converter was removed, the flywheel underneath is much lighter than all the rwd V6's. fyi the torque converter showed evidence of being balanced separately to the flywheel, neutral I believe. By retaining the stock balancing I avoided the necessity of otherwise getting the engine rebalanced, which helped my budget too. Although I will inspect the bottom end bearings for piece of mind when the car is off the road over winter.

The motor feels very smooth with no noticeable vibration across the usable rev range, as a huge positive it changes rpm far more rapidly, feeling much more "revvy" if that's a real word, but on the downside is also a bit easier to stall than before.

[Steve R]

Another small custom part, this photo shows the original Alfa 164 alternator mounting bracket modified by carefully positioning and welding some extra metalwork onto it. It now carries out the combined function of lower alternator mount to re-use the 164's much larger 120 Amp unit, the automatic belt tensioner bolts directly to the new metal and is in alignment for the belt routing, plus the main car body to engine earth strap bolts to this bracket. The tensioner itself is a new off the shelf stock unit from ford.

From the photo's in earlier posts you can see the alternator is in an unusual location high up in the engine bay, this isn't perhaps ideal, but it doesn't physically fit anywhere else. The top mount is simply a steel tubular arm made to fit snugly between the alternator lugs and the 164's top engine mounting bracket, thus the alternator is rigidly triangulated in place. The GTV6's massive standard washer bottle is replaced with a small aftermarket generic water bag in order to create enough space, this is a fair weather car so the loss of capacity is not an issue.

The power steering pump is now located down low on the block where the GTV6 alternator would normally be found, the 7 rib Alfa 164 pulley is bolted the ZF pump body of an Alfa 75 ps unit. The ps system was installed some years ago by an Alfa specialist, all I've done this time is relocate the pump to make room for the big alternator, relocate the reservoir, add a ps fluid cooling radiator (Jaguar X type or Ford Mondeo OEM art) to stop the fluid getting too hot, plus I renewed all the hoses as a matter of course. I don't have any pictures, but the ZF pump has decent mounting points on it, I just made some steel brackets to bolt it snugly in place to the block.

The idler wheels near the ps pump are held by the factory Alfa 164 bracketry, I cut the bottom part of this away to make room for my ps pump, but left the top and front intact in order to keep the idlers in standard position and perfect orientation to run my belt set up.

[Steve R]

The throttle valve, inlet plenum, runners and chargecooler set up (most would say inter-cooling, but that's an incorrect term and well described in GG's book).
A description first, then some photo's:

There was a choice to be made between the GTV6 style plenum versus the fwd style version, either would work absolutely fine with pros and cons either way. The GTV6 version would probably be easier but I opted for the fwd version partly because I just like the look of the chrome runners and partly because the accompanying injector rail set up is much more suitable for bigger injectors. I used a modified (chop the throttle flange off and weld a plate over, weld your throttle elsewhere as you see fit!) plenum from a 916 GTV, with 164 fuel rails, but any fwd plenum would probably be OK. There are two sizes of these chrome runners, 39mm and 44mm external diameter, apparently the larger ones are worth 20hp on an otherwise stock 3.0 24v, so I used the larger ones in an attempt to extract maximum power with minimal boost.

If I'd taken the rwd plenum route I'd have increased the airway sizing by grafted the big runner ports on from a fwd plenum and making shortened versions of the fatter runners. Not sure how much work (if any) the fuel rails would involve in this arrangement but I'd have used the newer 164 style anyway if at all possible.

Throttle position needed a decision: either before or after the supercharger... I went for before as it solves the problem of BIG pressure spikes when you shut the throttle. During the build I did try the throttle position between the compressor and the chargecooler but couldn't get a bypass valve fast enough acting to deal with the large pressure spikes in such a small volume, it ruptured 4 bar air hoses. The drawback of throttle before the SC is increased throttled volume which would soften throttle response if the volume were too big.

I considered the addition of chargecooling as a "must have" for reliability, the throttle position also influenced the type of chargecooling, air to air versus air / water / air. I chose the water cooled version partly for packaging of smaller hose runs and also the far smaller throttled volume. I felt it difficult to run big enough air pipes to and from a large front mounted cooler, plus it would have reduced throttle sensitivity.

After cutting matching holes in the plenum and chargecooler they were welded and leak tested by Elite who also did the manifolds earlier.

Some photos:

[Steve R]

ECU
I converted to Megasquirt to control the fuel injection about 12+ years ago, documented elsewhere on this site. A year or two after that I further converted the MS to also control spark timing rather than just fueling.

Interestingly by way of reliability - in the intervening decade I haven't touched it at all other than to make occasional tuning changes as other modifications have crept in. I've probably jinxed it now by implying it's reliable!!

This year however, I have carried further upgrade work to convert from single coil and distributor to 6x coils using the Alfa V6 COP system, with rpm now read from the stock 60.2 crank wheel and sensor rather than from the distributor. Six high power coil driving transistors have been added into to ECU to trigger the coils, these transistors are the same OEM items Bosch use in their own ECU's, so should be up to the job.

The ignition is set up as wasted spark using 3 ECU output channels to fire the coils in three pairs of two. The pairings are cylinders 1:5, 2:6 and 3:4, those pairings being "opposites" in the firing order.

The "how to" is documented in the MS literature, so I'll leave my description at that unless anyone would like more.

A couple of photos; mid install plus finished prior to adding the l-jet metal outer casing.

[Steve R]

Wanting the least restrictive and lowest back pressure exhaust down stream of the motor, a custom exhaust was made as I didn't think anything off the self was completely free flowing for 300ish hp.

Twin 2.25" downpipes and straight through front boxes, merging to single 3" with a flatter section where ground clearance is most critical around the crossmember. Then continuing 3" over the de dion, into a 3" box that splits back to twin 2.25". Curved outlets with polished slash cut tips finish it off so from the back it looks like an Ansa box. It was a tight fit around the rear axle and calipers, but the clearance is better than the angle of the photo seems to indicate. There are two flanges at the rear, one either side of the axle otherwise it was just too difficult to get the rear box on and off.

Made by Mike Stokes Motorsport in Bournemouth

Sound is very subjective, this is rather deeper tone than stock on tickover but still with that lovely V6 ripping howl in the mid and upper ranges. To be honest it's a bit too loud when cruising, but I love it I don't have a sound clip yet, I'll post a link once I do.