1.6 rebuild questions

[speed]

I have Wisco 8.5:1 pistons, Eagle rods and ARP hardware.

Still not 100% but I'm thinking that I'll sell the pistons and use stockies on the eagle rods. Are the stockies 9:1 comp ratio?

Will be getting the block cleaned up and honed. Head refreshed and assembled with possibly a skim, port and polish.

Crank will also be machined and bottom end balanced with new correctly sized quality bearings.

Now for some questions.

1. I know the 1.6 heads have poor flow compared to the 1.8
So am thinking the port and polish will help. I figure this a logical step since I'm doing everything else. Will this give me any gains, just not sure what to expect?

2. Will I need to upgrade my stock fuel pump to a Walbro or Deatschwerks?

3. How about the oil pump?

4. Will stock head bolts suffice or do I need ARP studs?

I'm expecting to run 16psi on my bush bearing T28 and would really like to see 185kw on the dyno with 98 ron fuel. May need to up the exhaust from 2.5 to 3 inches but again I'm not sure.

Am hoping to be ready to fit this built motor early next year and am currently just trying to accumulate the correct parts and get the necessary machining done in preparation.

Would be grateful for your feedback on the above questions

Thank you.

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[StanTheMan]

B6 static compression is 9.4:1. on OEM pistons unless there has been a shave or block has been decked.


flow.....unsure how much my basic port matched & polish did. I'll never know. Unlikely you'll make huge amount of difference to the flow. They talk about velocity being extremely important to the B6's. Unsure how that affects forced induction....probably less of a difference than if you were N/A like me.

I would certainly do it again. Because I enjoyed the journey.

[StillIC]

The B6 head and manifold is a bit crap if paired with longer duration cams. The intake cross sectional area is too small everywhere for the standard valves.

A significant cross sectional reduction occurs in the head where the one port splits into two before the valves. The join between the two intake ports needs to be knife edged, the right port D shaped and the left port back to front D shaped, then blended into the bowl before the valve. Your aim is to minimise sudden changes (especially larger to smaller) in cross sectional area as the air proceeds down the intake. This provides a reasonable improvement on its own and is worth doing IMHO.

If you want to get serious, you will need to increase the cross section everywhere in the head and then up into the manifold as well. I spent >40 hours porting my head/manifold: dimensions measured at various lengths, heights and widths accurate to 0.1 mm (and the ports are still too small as I couldn't reach far enough up into the manifold to make it larger where it needs it). I wouldn't bother doing this for a road car unless I was really chasing high rpm power for some reason.

Also, don't polish the ports. It reduces flow.

Another crap aspect of the B6 head is that, looking at the face of the head, the valves are tucked into the corners of the combustion chamber, which obstructs flow. Depending on your bore diameter, if you have some room for 'relieving the valves' consider it. But be aware that this will reduce your compression ratio, which you may not want. Your call on this.

Get the ARP studs as they are good and readily available. Get a billet oil pump if you regularly rev higher than, ummm, standard cut out (7400rpm ?).

[manga_blue]

Sometimes the manufacuring on B6 and early BP heads was pretty sloppy. That means that on some motors there are quite good gains to be made throughout the range and especially at the top end by just doing the simple things on them.

Check that the inlet manifold, gasket and head ports line up well without any overlaps, You can correct this with simple hand sanding with rolled up 120 grit general purpose sandpaper. If it's too bad (like manifold ports are offset more than 2mm over the port opening) then you may have to oval out the bolt holes on the inlet manifold mount and work out a way of lining it all up correctly again at final assembly, typically with either dowels or alignment marks.

Take out any casting faults and dags in the inlet tracts in both the manifold and the head by sanding and scrapng. Focus particularly on the areas between the valve seat and valve guide - the "bowl". As StillIC said, don't polish anything on the inlet side - always leave at least a 120 grit rough finish.

Likewise clean up the exhaust side and polish it there if you've got too much time on your hands - there are small gains from polishing there but they're only temporary.

Check the fit between throttle body and inlet manifold too. It may be necessary to file and sand off bumps and ridges in the manifold side of the union that are protruding into the main air flow.

[speed]

The B6 head and manifold is a bit crap if paired with longer duration cams. The intake cross sectional area is too small everywhere for the standard valves.

A significant cross sectional reduction occurs in the head where the one port splits into two before the valves. The join between the two intake ports needs to be knife edged, the right port D shaped and the left port back to front D shaped, then blended into the bowl before the valve. Your aim is to minimise sudden changes (especially larger to smaller) in cross sectional area as the air proceeds down the intake. This provides a reasonable improvement on its own and is worth doing IMHO.

If you want to get serious, you will need to increase the cross section everywhere in the head and then up into the manifold as well. I spent >40 hours porting my head/manifold: dimensions measured at various lengths, heights and widths accurate to 0.1 mm (and the ports are still too small as I couldn't reach far enough up into the manifold to make it larger where it needs it). I wouldn't bother doing this for a road car unless I was really chasing high rpm power for some reason.

Also, don't polish the ports. It reduces flow.

Another crap aspect of the B6 head is that, looking at the face of the head, the valves are tucked into the corners of the combustion chamber, which obstructs flow. Depending on your bore diameter, if you have some room for 'relieving the valves' consider it. But be aware that this will reduce your compression ratio, which you may not want. Your call on this.

Get the ARP studs as they are good and readily available. Get a billet oil pump if you regularly rev higher than, ummm, standard cut out (7400rpm ?).

Thanks Scott. I really appreciate you taking the time to explain what is required.

I'd be paying someone to do the porting. It certainly sounds as though a lot of precision is necessary, which I expected but now I have to be confident that the person I have in mind is familiar with the b6 head. Hopefully he describes it as you have, otherwise I'd not be willing to risk it.

It is a road car. Not sure where the rev cut is but I've never hit it whilst driving.
I don't expect that it would be above 7,000.

Cheers,
Sreve

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[speed]

Sometimes the manufacuring on B6 and early BP heads was pretty sloppy. That means that on some motors there are quite good gains to be made throughout the range and especially at the top end by just doing the simple things on them.

Check that the inlet manifold, gasket and head ports line up well without any overlaps, You can correct this with simple hand sanding with rolled up 120 grit general purpose sandpaper. If it's too bad (like manifold ports are offset more than 2mm over the port opening) then you may have to oval out the bolt holes on the inlet manifold mount and work out a way of lining it all up correctly again at final assembly, typically with either dowels or alignment marks.

Take out any casting faults and dags in the inlet tracts in both the manifold and the head by sanding and scrapng. Focus particularly on the areas between the valve seat and valve guide - the "bowl". As StillIC said, don't polish anything on the inlet side - always leave at least a 120 grit rough finish.

Likewise clean up the exhaust side and polish it there if you've got too much time on your hands - there are small gains from polishing there but they're only temporary.

Check the fit between throttle body and inlet manifold too. It may be necessary to file and sand off bumps and ridges in the manifold side of the union that are protruding into the main air flow.

Thank you Manga. So a general clean-up may reap some rewards depending upon the existing fitment. Will have to talk more about the bowl with the machinest.
He's built some great stuff over the years just dont think he's an mx5 expert though.

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