VR6 2.9 parts on a 2.8 block

[captainredeye 0]

Im having engine woes and debating starting from a fresh, although i would prefer to use a 2.9 block from a purest perspective i have come across a decent 2.8 small block and was wondering if anyone has used all the 2.9 parts i.e ecu, cams, throttle body, manifold, on a 2.8 block and if they have had it dynode or can even tell the difference.

i suspect there will still be a small amount of difference as its a smaller displacement, but would the ecu map needed remapping to make adjustments for the displacement change? even though i would be using all the 2.9 parts, just looking for some feed back to make my mind up on what direction to go in.

 

Cheers Ben

[Keyo 47]

What is wrong with your present engine block and it will give members a better  idea on input to your situation. Thing is you never want to go down in CC really . 

 

 

[seanl82 23]

The late MK3 Golf block was notoriously underreported for power output, but that was mostly down to OBD2 management using figures up toward 190 instead of the reported 175. The biggest gain though is apparently through the inlet, so putting a Corrado intake with the much larger plenum on a 2.8 block 'apparently' releases good gains and are very comparable with the 2.9 block. I can't comment from experience or do I have any RR figures to show you, bit it has been done numerous times without issue. A remap will likely wipe out any difference also between the two, so if your hand is forced, I wouldn't be too worried about a drop in performance.

[captainredeye 0]

I had a complete block i bought that had been in storage, rather than strip it i just put it in, some how a brake line connector had fallen into the chamber (through the spark plug hole at a guess)and when i cranked it with the starter to get fuel pressure it ruined the piston. i have started stripping and the whole block could do with an overhaul as the rod bearing look a little tired, a previous owner had also gone to the effort of doing a head gasket but not the tensioners and they have disintegrated so maybe a bit of a blessing in disguise ,if i can get a 2.9 block complete i will just go with that.

I would rather stick with the 2.9 as im sure it would niggle at me.

[Keyo 47]

What condition are the cylinders in, any scoring or ovulation  ? 

Edited March 16, 2020 by Keyo

[captainredeye 0]

Very light scoring but yet to check if its that time of the month😝 (sorry couldn't resist, spell checkers a T**T), need to get my hands on a gauge to test if they have ovalized.

[Keyo 47]

2 minutes ago, captainredeye said:

Very light scoring but yet to check if its that time of the month😝 (sorry couldn't resist, spell checkers a T**T), need to get my hands on a gauge to test if they have ovalized.

All down to budget then really- an experienced garage would charge you up to 4k for bottom and top end rebuild or a DIY maybe for around 2-2.5k. I know true 6   2.9 pistons   pistons would cost £850.00 alone as I have just purchased some. Also the cylinders do not take kindly to relining in a VR block so you would have to go up to a true 2.9 cc(cylinders bored out and pistons to match. As Sean says might be your best option with a 2.8 block but you would have to live with the power drop but not much is it 0.1 to be fair. 

[swiftkid 1]

I think the biggest thing for us Corrado owners is the whole thought process of "all you golf guys suck and we have a 2.9". The fact of the matter is, the 2.9 suffers from ovalisation of the bores more than 2.8. 

If you were thinking about swapping for the 2.8, get an OBD2 engine and just convert everything to OBD2. Having converted my 2.9 to OBD2, on paper the figures were not as impressive but real time driving, there was a massive mid range improvement with a bit of top end loss.

 

[fla 9]

you could get the 2.8 cylinders bored out to 2.9 and then you'd have a basically brand new block.  Not sure how much a machine shop would charge but i believe its not prohibitive, maybe someone with experience could advise.  You could then just use your normal 2.9 pistons.

 

I have to say they obd2 conversion and using an AAA intake manifold instead of the ABV did really improve the day to day driving of my car.  The schrick does help too, but that was a big investment!  As Swiftkid says the midrange improves immensely, but tbh I didnt really notice much top end difference

Edited March 17, 2020 by fla

[captainredeye 0]

I have a schrick manifold already so that should help matters, I have come across an afp 2.8 complete engine it requires some external parts swapping but from what I understand it’s the same.

i was quoted around 300 for a rebore a few years back, you need to find somewhere that has the machinery to bite at an angle 

[Keyo 47]

1 hour ago, captainredeye said:

I have a schrick manifold already so that should help matters, I have come across an afp 2.8 complete engine it requires some external parts swapping but from what I understand it’s the same.

i was quoted around 300 for a rebore a few years back, you need to find somewhere that has the machinery to bite at an angle 

Just make sure when they re bore that they measure each individual piston and bore per one. 

[Kevin Bacon 5]

Just get a complete engine from a late as possible MK3, along with the ECU, key and engine harness.  Going OBD2 was probably one of the best things I did to mine when it was naturally aspirated, along with a G60 final drive in the gearbox.  Both REALLY wake the car up.  Way more responsive.  

As said above, OBD2 2.8s made the same power as the 2.9 anyway, and it was a better engine.  Didn't suffer with ovalised bores on 1 & 6 half as much, and they just sounded smoother under acceleration, which was probably down to the more accurate fuelling and different intake manifold.

I wouldn't bother with the Schrick.  I always found those underwhelming for the money.  A set of Schimmel 263 cams yields the same gains anyway, if not more actually.