Big bore J20A
Moderator: Committee
Big bore J20A
I wonder how much meat is required around a cylinder liner to keep things happy? The reason I'm asking is the J20A 2.0 4cyl has a bore of 84mm. In the US they offered big bore version called the J23A with a 90mm bore. Both engines run the same 90mm stroke and the piston pin size is the same. I know of someone running an 87mm bore with Honda hi-comp pistons and he seems to think 90mm would be fine. If at some point the engine needed work it might be a mod to consider as it is internal therefore not visible to anybody and getting pistons, rings and a head gasket shipped wouldn't be too bad. The 2.3 offers an increase of around 20% more power and around 25% more torque over the 2.0 but I don't know how much of that may be contributed to by other factors such as the cams, valves etc. I've got a couple of pics of a J20A and I'm waiting for the guy to get me some measurements but looking at the pic I reckon the outer dia. is around the 101mm mark and if I used sleeves with a 2.5mm wall thickness I'd have a wall about 3mm surrounding that.
- Attachments
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- J20A head
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- J20A block
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- J20A block
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mightymouse
- Posts: 752
- Joined: Mon 13 Aug, 2007 9:19 am
- Location: Beginning to wish I didn't have to get under the Feroza.....
Re: Big bore
It depends exactly how much power you aim to make.
This type of unsupported liner tends to be reliable for medium RPM N/A engines. So if its torque your after lower down the range it is likely to be fine. if its going to be revved hard then its less suitable. Just don't forget that with the extra displacement comes the need for some more engine management, and we know the cost of quality tuning.
If you are buying new pistons / rings it can be quite expensive.
My comments are based on Daihatsu H series engines, but the block is very similar to the one shown
If boosted then much more of a problem, around 150kw+ its starts to be a bad idea - the bores start to walk and blown head gaskets become the norm. "O" ringing the head helps but the simple solution for that sort of power is to dowel the bores to the head.
Beyond 250kw a girdle is required, but it a lot of work machining the water jackets and liner outsides to a consistent profile and machining up the girdle. Obviously cooling channels need to be included. This will hold the bores well past 350kw+. But to reliably make that sort of power the cost of some cnc machining is peanuts anyway compared with all the other work.
When I was having my pistons made I was tossing up boring for some extra cc's - the advice from the experts was "leave the metal in - add more boost if you must".
So if its a low stressed application worth thinking about - but it limits further development work.
This type of unsupported liner tends to be reliable for medium RPM N/A engines. So if its torque your after lower down the range it is likely to be fine. if its going to be revved hard then its less suitable. Just don't forget that with the extra displacement comes the need for some more engine management, and we know the cost of quality tuning.
If you are buying new pistons / rings it can be quite expensive.
My comments are based on Daihatsu H series engines, but the block is very similar to the one shown
If boosted then much more of a problem, around 150kw+ its starts to be a bad idea - the bores start to walk and blown head gaskets become the norm. "O" ringing the head helps but the simple solution for that sort of power is to dowel the bores to the head.
Beyond 250kw a girdle is required, but it a lot of work machining the water jackets and liner outsides to a consistent profile and machining up the girdle. Obviously cooling channels need to be included. This will hold the bores well past 350kw+. But to reliably make that sort of power the cost of some cnc machining is peanuts anyway compared with all the other work.
When I was having my pistons made I was tossing up boring for some extra cc's - the advice from the experts was "leave the metal in - add more boost if you must".
So if its a low stressed application worth thinking about - but it limits further development work.
Re: Big bore
I know that there are power limits with it being an open deck design. I had been considering the idea of a little forced induction down the track but apparently these run a multi layer steel head gasket and the idea of the cylinder "walking" would more than likely lead to blown head gaskets 
doesn't appeal. The cost of fixing that issue just adds more $$$. The "Engineering", VicRoads & Insurance issues also come in to play. This is why I'm now thinking an increase in capacity may be a better option. I'm going to see if I can get a price on the genuine 2.3 pistons, rings and head gasket out of the US. Of course there is also the cost of re-sleeving too. The 2.3 delivers 116kw@5400rpm & 206Nm@3000rpm compared to my 97kW@6300rpm & 166Nm@2900rpm. I figured that with a decent exhaust (already have the headers waiting), a snorkel (less restrictive intake than standard) which is coming and the Haltech Interceptor that I have that it should deliver plenty enough for my needs. i have also just found out that Tighe Cams who did my 1.6 cam have done some work with these cams so that is another avenue. Apparently underdrive pulleys make quite a difference on these, particularly the autos. Another person I have been in touch with has swapped in a Ford XF throttle body and found very good gains from that, in fact much more than from the exhaust and ECM changes he made to it. There are certainly some options available although I am in no rush, just investigating for the future.
doesn't appeal. The cost of fixing that issue just adds more $$$. The "Engineering", VicRoads & Insurance issues also come in to play. This is why I'm now thinking an increase in capacity may be a better option. I'm going to see if I can get a price on the genuine 2.3 pistons, rings and head gasket out of the US. Of course there is also the cost of re-sleeving too. The 2.3 delivers 116kw@5400rpm & 206Nm@3000rpm compared to my 97kW@6300rpm & 166Nm@2900rpm. I figured that with a decent exhaust (already have the headers waiting), a snorkel (less restrictive intake than standard) which is coming and the Haltech Interceptor that I have that it should deliver plenty enough for my needs. i have also just found out that Tighe Cams who did my 1.6 cam have done some work with these cams so that is another avenue. Apparently underdrive pulleys make quite a difference on these, particularly the autos. Another person I have been in touch with has swapped in a Ford XF throttle body and found very good gains from that, in fact much more than from the exhaust and ECM changes he made to it. There are certainly some options available although I am in no rush, just investigating for the future.-
mightymouse
- Posts: 752
- Joined: Mon 13 Aug, 2007 9:19 am
- Location: Beginning to wish I didn't have to get under the Feroza.....
Re: Big bore
If by "multilayer steel head gasket" you mean a decompression shim with a head gasket each side - then that's a rough and ready solution.
In the old days of ford turbos kits ( I am showing my age..... ) that was the base option - the absolute minimum and limited durability. Was actually more reliable to remachine the piston crowns and I am also not a fan of that to any great degree.
Most of the time "properly"= money, although I agree that cumulatively sensibly applied small changes can make a surprising difference. The trouble is most people assume that their mods are cumulative when often they work at crossed purposes.
Go to love dyno's.
In the old days of ford turbos kits ( I am showing my age..... ) that was the base option - the absolute minimum and limited durability. Was actually more reliable to remachine the piston crowns and I am also not a fan of that to any great degree.
Most of the time "properly"= money, although I agree that cumulatively sensibly applied small changes can make a surprising difference. The trouble is most people assume that their mods are cumulative when often they work at crossed purposes.
Go to love dyno's.
Re: Big bore
No Ross, the multi layer steel (MLS) head gasket I was referring to is what they use as standard.
http://www.jegs.com/webapp/wcs/stores/s ... 9_-1_10193
http://www.jegs.com/webapp/wcs/stores/s ... 9_-1_10193
Re: Big bore
There was a J20A with a blown bottom end on ebay that would have been nice to have picked up cheap (it got no bids) to pull apart and have a play with but it was in W.A. so the shipping would have been a killer Would have provided a head and cams too.
I emailed LA Sleeve the pics of the block and told them what I want to do and I got this reply'
"We haven't made a performance sleeve for the Suzuki yet but it looks possible. Looking at the picture you emailed, it seems to me like it would be simular to the Honda's we make sleeves for. We would make the flange bigger than the waterjacket. Usually 1.500" down on the flange. Then, the outer diameter would taper down below that. It would press on that area of the sleeve. Depending on what aluminum is left between each bore is what determines your press fit. The average press fit is .001 to .002. Let me know if you've any other questions."
Would have provided a head and cams too.I emailed LA Sleeve the pics of the block and told them what I want to do and I got this reply'
"We haven't made a performance sleeve for the Suzuki yet but it looks possible. Looking at the picture you emailed, it seems to me like it would be simular to the Honda's we make sleeves for. We would make the flange bigger than the waterjacket. Usually 1.500" down on the flange. Then, the outer diameter would taper down below that. It would press on that area of the sleeve. Depending on what aluminum is left between each bore is what determines your press fit. The average press fit is .001 to .002. Let me know if you've any other questions."
Re: Big bore J20A
In markets such as North America, Europe, Japan and the Middle East the new Gen 2 Grand Vitara's and the SX4's fitted with the J20A have a 10.5:1 comp ratio compared to our 9.5:1. The pistons are different for these markets and the part numbers are 12100-65820-0A0 for red piston
12100-65820-0B0 for blue piston
It might not be much but for those who happen to be rebuilding an engine and looking for a bit more power it may be worthwhile importing some high comp pistons and running it on 98.
12100-65820-0B0 for blue piston
It might not be much but for those who happen to be rebuilding an engine and looking for a bit more power it may be worthwhile importing some high comp pistons and running it on 98.