RB26 intake manifold on RB20

[Dose Pipe Sutututu]

Looks great, but all that time/money/stress you could have put in a RB26 lol

[GTSBoy]

Yuh, the original WOFTAM, multiplied by double.

[iruvyouskyrine]

Mine leaked like a sieve exactly where you were worried that it would leak from. I also had all the issues that you had RE thermosat housing and lower coolant passage. What exactly did you do next to the coolant passage at the front of the adapter to stop it leaking?

[iruvyouskyrine]

Okay i re-read it and it looks like you drilled out the threads on the RB26 side of the adapter and the bolt that mates the ITB to the RB26 side of the adapter now goes through the ITB's, RB26 side, RB20 side and directly into the head? is that correct?

[Jordie Lewis]

On 6/26/2020 at 7:11 PM, iruvyouskyrine said:

Okay i re-read it and it looks like you drilled out the threads on the RB26 side of the adapter and the bolt that mates the ITB to the RB26 side of the adapter now goes through the ITB's, RB26 side, RB20 side and directly into the head? is that correct?

This is correct. the holes lined up perfectly here. So I drilled the threads out and de-burred the holes. 

There were a couple other holes which almost lined up but were not spot on and would require some enlarging to fit properly. 

Ill see how it goes, my injector seals showed up this morning so It shouldn't be much longer before I try and fire it up. Ill keep you all posted.

-Jordie

 

[iruvyouskyrine]

I just took all mine apart and you are correct, that's an excellent idea, wish I did it 3 years ago. I'll take some more pics for people as well when it all goes back together. I just sent all my stuff off to high octane today to be coated.

[Jordie Lewis]

On 6/25/2020 at 7:11 PM, Dose Pipe Sutututu said:

Looks great, but all that time/money/stress you could have put in a RB26 lol

Damn. I really wish they had $500 RB26's where I live. Would have saved me lots of headaches. ?

8 hours ago, iruvyouskyrine said:

I just took all mine apart and you are correct, that's an excellent idea, wish I did it 3 years ago. I'll take some more pics for people as well when it all goes back together. I just sent all my stuff off to high octane today to be coated.

Yea. I was surprised that Otaku didn't do that from the get go. I used an M8 x 80mm bolt to go through everything and thread into the block. 

Did you make a gasket for in-between the plates as well, or did you just use RTV?

[Jordie Lewis]

Can confirm Otaku plates leak like a sieve. There are just too many failure points. 

I slapped on my old setup so I can at least enjoy my car for the rest of the summer. Ill revisit this again over the winter. 

Am gutted.

[iruvyouskyrine]

Haha, whats leaking, air or water? Where is it leaking for you?

[Jordie Lewis]

On 7/31/2020 at 4:05 AM, iruvyouskyrine said:

Haha, whats leaking, air or water? Where is it leaking for you?

it started leaking at the back. it looks like when I bolted the RB26 balance tube piece on, one of the bolts was a little proud and caused the plates to separate. New gaskets should be here today so Ill try again

[iruvyouskyrine]

The balance tube is the top piece that links all the ITB's together to get an average pressure reference source, so that shouldn't be able to effect the sealing of the manifold? 

I have spent probably 15 hours assembling, measuring, checking and modifying the adapter so far. Has been on and off the engine 20 times. I ended up doing what you did and drilled out the adapter plate on the locations where the RB26 bolt holes align to the RB20 (which i think is 10 bolts IIRC) and measured for all brand new bolts. I have some pics i might throw up later on but it's almost ready for final installation now.
Im using 2x OEM fibrous RB20 inlet manifold gasket and the rest is Siruda RB26 metal inlet gasket set. I used a dickload of RTV last time but think im just going to use straight gaskets only this time.

[Jordie Lewis]

4 hours ago, iruvyouskyrine said:

The balance tube is the top piece that links all the ITB's together to get an average pressure reference source, so that shouldn't be able to effect the sealing of the manifold? 

no no I mean the cast portion of the intake manifold assembly. that goes between the throttle body and the adapter plate. I have it all apart again now. going to take another crack at it.

[Jordie Lewis]

On 8/5/2020 at 5:02 AM, iruvyouskyrine said:

 

 I ended up doing what you did and drilled out the adapter plate on the locations where the RB26 bolt holes align to the RB20 (which i think is 10 bolts IIRC) and measured for all brand new bolts. I have some pics i might throw up later on but it's almost ready for final installation now.
 

Got everything all apart again last night. You're right, 10 holes line up with those in the block. I am going to drill out the threads and get fasteners to go right through the plates into the block. There seems to be enough tolerance in the holes that if they are not 100% bang one (less than 1-2mm either way) it should still all bolt up.  I believe that I have the right fasteners for the job but Ill assemble tonight without gaskets and double check.

-Jordie

 

 

 

 

Edited August 6, 2020 by Jordie Lewis

[iruvyouskyrine]

I had to drill them all out to 9.5-10mm just because of the variance that you get when bolting the adapter plate together. Even though it uses countersunk screws it seems to move very slightly each time which is a pain so I just went straight to 10mm

[Jordie Lewis]

I drilled them all out to 9.5mm and everything mounted up just fine. I used a little bit of RTV sealer to make sure it seals well. I filled the coolant with water to check for leaks and we are all good 

(yes I have added rad hose clamps )

Just need to get some cold side piping fitted and I should be able to start it all tonight. Fingers crossed.

[Jordie Lewis]

Just to update everyone. 

Got the car together and running. No leaks or big dramas. 

Ive adjusted the ITBs and managed to get everything to idle at around 1050-1100 RPM. Which seems decent by old ITB standards. Since im an expert at removing it all, I might try from throttle coat over the winter. 

Drove it to work today and it ran super well (surprisingly) with my tuned ecu. Once I figure out a turbo and manifold I will properly get it mapped.

If anyone has any questions about this conversion, feel free to inbox me. 

 

[r33cruiser]

Must....have....separate......build.....thread  

[Jordie Lewis]

10 hours ago, r33cruiser said:

Must....have....separate......build.....thread  

Here you go. Not on SAU but its pretty detailed. You might need the photobucket fix extension for chrome to see the first post but other than that its all though flickr so it mostly works. 

https://zilvia.net/f/showthread.php?t=579803

Enjoy

-Jordie

[r33cruiser]

[iruvyouskyrine]

This is why you don't use this kit.

Brand new genuine gaskets, Brand new adapter plate, all surfaces machined flat, brand new bolts. Modified the adapter plate like above to have the bolts go all the way through and secure it to the head. There was absolutely nothing more i could have done to give it a better chance at sealing. This is using a cooling system pressure tester at anything above 2-3psi. was obviously much worse at 15psi.

I would have spent probably 30+ hours in trying to make this piece of shit work properly. 

Literally the only option i have left is to remove it all again and instead of using proper gaskets just gasket goo the ever loving f**k out of everything which really isn't right.