User Login    
 + Register
  • Main navigation
Login
Username:

Password:


Lost Password?

Register now!
Fast Search
Slow Search
Google Ad



Browsing this Thread:   1 Anonymous Users





A15 piston help
Home away from home
Joined:
2011/11/26 1:02
From Canberra
Group:
Registered Users
Posts: 604
Offline
Hey boys i have picked up another A15 and opened it up to inspect it all and have come to notice the pistons in the engine are 1mm over bore 77mm and the block is oringed

now the question is that the pistons have a very minor dish on them and almost look early a-series what im wanting to know is are they are higher compression verse the quelsh ofset stock a15 pistons and will it be alright to put on a H89 head on it as the pistons come a around 1mm above block height as well im just a little confused verse the normal stock pistons

wanting to know if it will have a higher comp and the h89 head will be good on it

here is the A15 opened up and the other picture is a standard A15 piston

Attach file:



jpg  20170827_095615.jpg (133.80 KB)
16063_59a26c3295da3.jpg 397X706 px

jpg  20170827_095629.jpg (150.08 KB)
16063_59a26c5c693c4.jpg 545X968 px

Posted on: 2017/8/27 7:53
_________________
Transfer the post to other applications Transfer


Re: A15 piston help
Home away from home
Joined:
2005/2/23 6:14
From gold coast QLD australia
Group:
Registered Users
Posts: 538
Offline
What style head was on the A15.probably had indent to take piston.

Posted on: 2017/8/27 8:19
_________________
GO RACING,GO HARD OR GO HOME!!
SLY OLD FOX..................
Transfer the post to other applications Transfer


Re: A15 piston help
Home away from home
Joined:
2011/11/26 1:02
From Canberra
Group:
Registered Users
Posts: 604
Offline
it had a H75 head on it for some reason and the combustion chamber on the head has not been modified can get pics if you boys would like to see the head that came off it

Posted on: 2017/8/27 8:21
_________________
Transfer the post to other applications Transfer


Re: A15 piston help
Moderator
Joined:
2001/5/3 7:04
From 48 North
Group:
Registered Users
Contentmaster
Usermaster
Posts: 31575
Offline
A15s came with at least different style pistons over the years/markets:
* H97 dished pistons (shallow dish)
* H97 dished pistons (bigger dish)
* H98 offset dished pistons
* G34 offset dished pistons
* H92 offset dished pistons
Open in new window

Posted on: 2017/8/27 8:34
Transfer the post to other applications Transfer


Re: A15 piston help
Home away from home
Joined:
2005/2/23 6:14
From gold coast QLD australia
Group:
Registered Users
Posts: 538
Offline
There are so many head and piston combinations you would have to CC the head and pistons and workout the comp ratio

Posted on: 2017/8/27 8:49
_________________
GO RACING,GO HARD OR GO HOME!!
SLY OLD FOX..................
Transfer the post to other applications Transfer


Re: A15 piston help
Moderator
Joined:
2001/5/3 7:04
From 48 North
Group:
Registered Users
Contentmaster
Usermaster
Posts: 31575
Offline
Quote:
the pistons come a around 1mm above block height
That is non-standard, someone has machined the block deck height

With open chamber heads it may be OK, but with H89 closed chamber head it is not safe without measuring the head gasket. I'd reckon a 1.6 mm head gasket might just allow enough clearance if the revs are kept stock, but with either Nismo head gasket the pistons will contact the head. Bang!

Posted on: 2017/8/27 9:03
Transfer the post to other applications Transfer


Re: A15 piston help
Home away from home
Joined:
2011/11/26 1:02
From Canberra
Group:
Registered Users
Posts: 604
Offline
cheers guys, yeah think best bet is going to be get it compression checked and check the combustion chamber against the closed chamber h89 make sure its all lined up, henceforth ensure this deck clearance is correct and match headgasket to get the most out of it..

Still a decent little win to have the block bored 1mm over and oringed better than me having to do it :)

Posted on: 2017/8/27 11:06
_________________
Transfer the post to other applications Transfer


Re: A15 piston help
Home away from home
Joined:
2005/2/23 6:14
From gold coast QLD australia
Group:
Registered Users
Posts: 538
Offline
You find some good stuff now and then.
I am building an A14 race motor from the ground up.have 6months to do it

Posted on: 2017/8/27 11:11
_________________
GO RACING,GO HARD OR GO HOME!!
SLY OLD FOX..................
Transfer the post to other applications Transfer


Re: A15 piston help
No life (a.k.a. DattoMaster)
Joined:
2002/11/26 0:38
From Las Vegas USA
Group:
Registered Users
Posts: 2032
Offline
The other possibility beside the block being decked is the pistons are non Nissan. I seem to recall some manufacturer using a 30.5 pin height in a 77mm piston or NOT .

I too would be a bit nervous with the pistons being proud of the block; besides what it may do to the quench etc there are also going to be valve clearance considerations. In theory the pistons could be milled.

Obviously everything will have to be measured.

Posted on: 2017/8/27 19:34
Transfer the post to other applications Transfer


Re: A15 piston help
Home away from home
Joined:
2010/3/20 12:20
From Sydney Australia
Group:
Registered Users
Posts: 238
Offline
The block would have been decked no two ways about that the thing is how much,When doing "O" ringing one always decks the block.

I used to do it with a jig basically a ground steel bar on mounts so the block sat on the main bearing tunnel and was clamped in this position on the mill bed that way the deck surface of the block is guaranteed square to the crank.

Even if not doing an "O" ring number for turbo applications or to make a standard head gasket work similar to an FIA gasket that has a stainless "O" ring withing the gasket just behind the fire ring we always decked the blocks that way so when using a strap on boring bar you make certain the bore job is square to the crank.

Strap on boring bars work much better than the later style Mill type boring machines as there is less harmonic vibration with them and you can bore much closer to final required size requiring minimal honing to give the correct finish without any boring marks left from machining giving a much more accurate finish even with a Sunnen honing machine.

That of course means better sealing of the ring pack and hence much better power results.

There are machinists and there are machinists when it comes to engine work make sure they really know what they are doing for the best results

Posted on: 2017/10/1 22:24
Transfer the post to other applications Transfer






You can view topic.
You cannot start a new topic.
You cannot reply to posts.
You cannot edit your posts.
You cannot delete your posts.
You cannot add new polls.
You cannot vote in polls.
You cannot attach files to posts.
You cannot post without approval.

[Advanced Search]