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Post by mrwallace on Jan 7, 2020 13:09:33 GMT
Good power for your mods on that dyno run, mine should be similar at the moment. So the manifold you've bought doesn't have the VICS gubbins? Should be a stright fit then using the MK2 head? Still keen to see what this yields  |
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Post by scottydugg on Jan 8, 2020 11:48:42 GMT
Good power for your mods on that dyno run, mine should be similar at the moment. So the manifold you've bought doesn't have the VICS gubbins? Should be a stright fit then using the MK2 head? Still keen to see what this yields Yeah the mk2.5 inlet manifold fits the mk2 head and doesn't have VICS. I've done a bit more digging regarding how much to skim the head by. There's a lot of discussion out there but not a huge amount of information. I've seen 80thou down to 8 discussed, I read one that said 30thou means 95ron is still safe to use. I can't get a definitive answer on stock ECU/stock cam gears and what depth is safe to take off. Leaning towards 30thou, for no other reason than I was considering 20 and 40. Going to try get it dropped off on Friday for the skim. Any input welcome as always. |
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Post by Whistler on Jan 8, 2020 15:12:54 GMT
IIRC you can go to 60 thou (assuming you fit a standard head gasket which is 20 thou), but things are super close. The only way to know for sure is to use plastigauge. You should be safe with 40 thou.
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Post by Zed. on Jan 8, 2020 16:28:23 GMT
I understand that the internot diagnoses many things BUT it's worth doing the mathematics YOURSELF before having any metal removed  Rich. |
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Post by dickie on Jan 8, 2020 17:11:23 GMT
Just from my experience.
A Mk2 head skimmed by 60 thou is fine on a Mk2.5 block with 10.5 to 1 pistons with Piper 285 regrinds.
You will need to re-time camshafts with anything much over 10 thou as the timing gets retarded, without re-timing cams you will be losing some of the gains from increased compression.
With a 60 thou skim you can still use the OEM timing belt tensioner but its getting close to its limit.
A second hand Mk 2.5 block ( gives 10.5 to 1 CR and a better oil pump )with the Mk 2 head gives you all the gains with no downsides as all the timing stays the same.
If its a Mk1 1800 you can take all the sensors from that and swap them onto the Mk2 head Mk 2.5 block.
As they say on the Telly The Decision is Yours.
I used info from Garage Quinn Motors for my engine.
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Post by wannabe on Jan 8, 2020 17:30:20 GMT
I understand that the internot diagnoses many things BUT it's worth doing the mathematics YOURSELF before having any metal removed Rich. This. lol Do some measurements before you do anything!  |
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Post by Zed. on Jan 8, 2020 17:58:44 GMT
I understand that the internot diagnoses many things BUT it's worth doing the mathematics YOURSELF before having any metal removed Rich. This. lol Do some measurements before you do anything! Do as I say not as I do?   Rich. |
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Post by scottydugg on Jan 8, 2020 23:59:32 GMT
Just from my experience. A Mk2 head skimmed by 60 thou is fine on a Mk2.5 block with 10.5 to 1 pistons with Piper 285 regrinds. You will need to re-time camshafts with anything much over 10 thou as the timing gets retarded, without re-timing cams you will be losing some of the gains from increased compression. With a 60 thou skim you can still use the OEM timing belt tensioner but its getting close to its limit. A second hand Mk 2.5 block ( gives 10.5 to 1 CR and a better oil pump )with the Mk 2 head gives you all the gains with no downsides as all the timing stays the same. If its a Mk1 1800 you can take all the sensors from that and swap them onto the Mk2 head Mk 2.5 block. As they say on the Telly The Decision is Yours. I used info from Garage Quinn Motors for my engine. Is that on a stock ecu? If so that sounds a good option. I'll get him the height tolerance and see what he says anyway. Thanks guys. Edit: After a bit of reading the VVT block would need an aftermarket ECU. I think for this stage I'll the machine shop to check the depth and do a minimal skim for now. Leaves options open for the future. A small project was starting to snowball into something daft. Manufacturer head height is 133.8-134.0mm from the information I can find on the Beavis Motorsport site. I'll guess that it's the same for the Mk1 head and the Mk2 (BP4W). |
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Post by Vindi (Russell) on Jan 10, 2020 8:54:12 GMT
I keep coming back to this thread, I guess that says a lot about what I really like ... standard engine, lightly warmed. My engine currently is a Mk2 RS, with the usual suspects bolted on ... decent manifold, exhaust, decat and a cone filter on the intake. Hoping that it gets 145 but with an ECU it should get to 150
Russell
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Post by scottydugg on Jan 10, 2020 15:18:43 GMT
I keep coming back to this thread, I guess that says a lot about what I really like ... standard engine, lightly warmed. My engine currently is a Mk2 RS, with the usual suspects bolted on ... decent manifold, exhaust, decat and a cone filter on the intake. Hoping that it gets 145 but with an ECU it should get to 150 Russell The only thing I wish I'd of bought when I had the chance was a Jackson Racing intake, they seem to get the best gains from what I've read. Not sure what the differences are on an RS but I'd imagine you'd get above what I do. Mk2.5 bottom end, aftermarket cams and an ECU would be the ideal scenario. Maybe it's an ITB build you're really wanting to build? Dropped the head off at the machine shop last night, he's going to check the dimensions, but it's still got the factory machining marks so confident it's not been skimmed before. I've asked for a 20thou skim. Just need some assembly lube, tweezers and butcher a socket for fitting the valve retainers...then I'm good to go on re-assembly. |
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Post by dickie on Jan 10, 2020 16:52:18 GMT
Hi,
If you run a Mk2.5 block with a Mk2 head and cams the standard Ecu should be able to cope.
You keep the standard cams and use the Mk2 plenum with the throttle body you want to fit.
If you use the Mk1 throttle body you do not need to mess around with too much.
All you are doing is a compression ratio bump without changing anything else.
This should gain torque and fuel economy.
I have gone over the top with my engine as I have time money and space to do it ( I am using the latest version of the ME221 )
I am using the standard TPS and throttle quadrant grafted onto the GSXR Itbs.
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Post by Vindi (Russell) on Jan 10, 2020 23:42:39 GMT
I keep coming back to this thread, I guess that says a lot about what I really like ... standard engine, lightly warmed. My engine currently is a Mk2 RS, with the usual suspects bolted on ... decent manifold, exhaust, decat and a cone filter on the intake. Hoping that it gets 145 but with an ECU it should get to 150 Russell The only thing I wish I'd of bought when I had the chance was a Jackson Racing intake, they seem to get the best gains from what I've read. Not sure what the differences are on an RS but I'd imagine you'd get above what I do. Mk2.5 bottom end, aftermarket cams and an ECU would be the ideal scenario. Maybe it's an ITB build you're really wanting to build? Dropped the head off at the machine shop last night, he's going to check the dimensions, but it's still got the factory machining marks so confident it's not been skimmed before. I've asked for a 20thou skim. Just need some assembly lube, tweezers and butcher a socket for fitting the valve retainers...then I'm good to go on re-assembly. RS just has a slightly higher compression and rev limit from what I can remember, 3bhp more than a standard Mk2 1.8 according to Mazda so not a lot. I want to keep it simple really. TBs add a lot of noise and drama, but very little extra power for the money, the power is almost all in the head work / tuning from what I can tell, unless you go really crazy Russell |
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Post by dadbif on Jan 11, 2020 8:26:34 GMT
As mentioned before, pre fit the head without a head gasket and turn the engine over with some plasticine on the piston crowns, a lot safer (and potentially cheaper) than bolting it down and firing it up...
You’ll be left with a witness showing how close the valves come to the pistons, not forgetting things can “float” a bit at high revs.
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Post by scottydugg on Jan 14, 2020 10:52:35 GMT
Thanks for the advice everyone.
Spent some time cleaning up the gasket for the inlet manifold halves, it came off easily enough and hasn't damaged it, so that's a saving of £30.00. The paint on the manifold could be doing with a re-do so I'll maybe go over it with some black VHT wrinkle paint.
Whilst I'm waiting on the head to be machined, I'm going to start attacking the valves with some brass wire brush, tape of the area that sits within the guides. Do I need to avoid the area that contacts the valve seat in the head? These will be lapped later on regardless.
I've some pictures I'll upload later on.
Edit:
I'm also doing a bit of reading about which injectors to use, the consensus being that you need to use the mk2 fuel rail to fit the BP4W as it has a different offset, but also the FPR on the mk2 will run at 60psi(mk2) as opposed to 43psi(mk1), so the mk2 Injectors should be fine as long as it's matched to the correct FPR.
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Post by FFS Corders on Jan 14, 2020 17:11:30 GMT
I run the mk2 fuel rail and injectors, with the mk1 loom
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le sigh