OST-077: Nothing double natural about twincharging
05-24-2021, 10:16 PM
Post: #1
OST-077: Nothing double natural about twincharging
[Image: AEU86 AE86 - OST-077: Nothing double nat...incharging]


So in October of 2020 my client contacts me about building him a head for a twincharge build.

He'll will be running a supercharger from a Mazda Millenia, and the turbo he is planning on is TD06sl2-20g




The head arrives, and gets dismantled, and sent out to be cleaned.

[Image: AEU86 AE86 - OST-077: Nothing double nat...incharging]


once back, it gets measured.... it has been machined before... 0.12mm, or about .005"

[Image: AEU86 AE86 - OST-077: Nothing double nat...incharging]


The head gets deburred....

[Image: AEU86 AE86 - OST-077: Nothing double nat...incharging]


And as this will be running substantial boost, ARP studs will be used, so clearance is added so the studs can't interfere with oil flow

[Image: AEU86 AE86 - OST-077: Nothing double nat...incharging]


More to come..... Hurray!

Dan -

You can |Sad .... OR you can ask for help!!!

OST Porting service - http://hachiroku.net/forums/showthread.php?t=19991
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05-25-2021, 11:41 AM (This post was last modified: 05-25-2021 11:41 AM by banpei.)
Post: #2
OST-077: Nothing double natural about twincharging
A twin charge! That's interesting and I'm looking forward to see this progress! Thumbs up!

1982 - TA60 Carina 4dr sedan - fun cruiser
1983 - AE86 Sprinter Trueno - import project
2013 - Honda Civic sport - daily driver
2004 - AEU86 dot ORG - daily domain

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[Image: AEU86 AE86 - OST-077: Nothing double nat...incharging]
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05-27-2021, 05:16 PM
Post: #3
OST-077: Nothing double natural about twincharging
(05-25-2021 11:41 AM)banpei Wrote:  A twin charge! That's interesting and I'm looking forward to see this progress! Thumbs up!
Thumbs up!

1down

[Image: AEU86 AE86 - OST-077: Nothing double nat...incharging]


As this is a boosted build that will be running up to 40 psi, every effort is being made to minimize detonation, including "softening" the spark plug opening.

[Image: AEU86 AE86 - OST-077: Nothing double nat...incharging]


Also the exhaust ports are opened up a fair bit

[Image: AEU86 AE86 - OST-077: Nothing double nat...incharging]


more to come.... Hurray!

Dan -

You can |Sad .... OR you can ask for help!!!

OST Porting service - http://hachiroku.net/forums/showthread.php?t=19991
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05-31-2021, 09:09 PM
Post: #4
OST-077: Nothing double natural about twincharging
Could you point a tell a bit more about this comment: And as this will be running substantial boost, ARP studs will be used, so clearance is added so the studs can't interfere with oil flow

Thx

Restoring my AE86, all the way... Going JDM style Big Grin
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06-02-2021, 12:10 AM (This post was last modified: 06-02-2021 12:11 AM by oldeskewltoy.)
Post: #5
OST-077: Nothing double natural about twincharging
(05-31-2021 09:09 PM)Vaptor Wrote:  Could you point a tell a bit more about this comment: And as this will be running substantial boost, ARP studs will be used, so clearance is added so the studs can't interfere with oil flow

Thx

The oil feeds the head at #1 bolt on the exhaust side. Essentially when you use ARP studs, there is a possibility that the shank of the stud can interfere with that small hole that directs oil to the head, and cams.

When you use a stock type bolt, they have a shank-down section which can't interfere with the oiling.

[Image: AEU86 AE86 - OST-077: Nothing double nat...incharging]

The ARP stud has nothing to keep the bolt free of the oiling hole. The problem was somewhat mitigated when ARP changed the stud diameter from 10mm, down to 9.2mm, but it is still possible to cause an issue.

Formula Atlantic builders began by drilling #1 exhaust bolt hole from the bottom up, stopping just after the oil feed hole. The only problem with this method is when lowering the head the stud can "catch" on the edge created by over-drilling the bolt hole. I did this as well, until I got to OST-044, a 7AF head....

[Image: AEU86 AE86 - OST-077: Nothing double nat...incharging]

Note all the bolt holes are flush for the washer, except the one in the lower right - #1 on the exhaust side. Here was a factory modification the factory took from Atlantic and incorporated into a stock head.

I just took their lead and have run with it.

[Image: AEU86 AE86 - OST-077: Nothing double nat...incharging]



back to this head.....


2 down - getting that exhaust opened for more flow

[Image: AEU86 AE86 - OST-077: Nothing double nat...incharging]


and now to 3 down

[Image: AEU86 AE86 - OST-077: Nothing double nat...incharging]


more to come...... Hurray!

Dan -

You can |Sad .... OR you can ask for help!!!

OST Porting service - http://hachiroku.net/forums/showthread.php?t=19991
Find all posts by this user
06-07-2021, 06:14 PM
Post: #6
OST-077: Nothing double natural about twincharging
[Image: AEU86 AE86 - OST-077: Nothing double nat...incharging]


With the port work complete, it is off to get its valve job.


As this head will be running substantial boost levels, minimum specs (.5mm valve margin) just will not cut it, and the original exhaust valves while still within those minimums are just too thin............. I find 8 replacements with more margin.

[Image: AEU86 AE86 - OST-077: Nothing double nat...incharging]


More to come...... Hurray!

Dan -

You can |Sad .... OR you can ask for help!!!

OST Porting service - http://hachiroku.net/forums/showthread.php?t=19991
Find all posts by this user
06-12-2021, 09:12 PM
Post: #7
OST-077: Nothing double natural about twincharging
As this is being twincharged (for those unknowing - twincharge is using both a supercharger and turbocharger in the same engine)...... Coming up with a cam for this beast was no easy task. After consulting with the engineers @ Cat camshafts, a "new" camshaft design was built.

258 overall, [email protected](.040") with 9.25mm of cam lift.

[Image: AEU86 AE86 - OST-077: Nothing double nat...incharging]


This cam should tick all the boxes, but to run this aggressive of a cam a shim over system just will not work, so this head will be running 1SZ shimless buckets.


To do this I have a set of 8 "sizing" buckets (8 of the thinnest) that I'll use to determine actual clearances, and then order the appropriate bucket to set the clearances.

[Image: AEU86 AE86 - OST-077: Nothing double nat...incharging]


More to come.... Hurray!

Dan -

You can |Sad .... OR you can ask for help!!!

OST Porting service - http://hachiroku.net/forums/showthread.php?t=19991
Find all posts by this user


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