HKS bottom mount manifold; divider wall cracked. What do I do?

[mello88]

So I recently picked up a used HKS cast bottom-mount manifold for my RB. But upon closer inspection I've found a problem with it that really bothers me, it has a crack on the divider wall inside. I hope you guys can give some advice on how I should proceed...

Here's how the manifold looks on there with the stock turbo. Nevermind the PB blaster on there, I had to get 1 stubborn stud and 1 snapped stud out.



Now upon closer examination of the manifold, I noticed a small crack in the divider wall that seperates the pulses from cyl 123 and 456.

This is looking down from the top, into the wastegate port. Sorry the picture is so blurry, but look in the middle-lower half of the wall or check out the next pic.



This divider wall runs all the way up from the turbine inlet flange to the wastegate port. Here you can see the crack pretty well



In the last picture, you can see the crack. It runs for the entire vertical length of the divider wall and is visible from both the wastegate port and the turbine flange .

Obviously my fear is that the wall will become brittle with the high temps and slowly fragment, sending chunks into my turbine . I am ordering a gt28rs soon and I sure as **** don't want to chunk it to death! :bite:

What are your thoughts or suggested solutions... I would love to get this manifold repaired or otherwise usable again. I can't think of a way to fix it without totally removing that wall. I was planning to send this out for ceramic coating, but it's kind of on hold until I can figure this one out.

Thanks in advance

[SeVa-S13]

Each and every used HKS RB manifold has that, mine included. (Welcome to the club, w00t.)Waiting for my next engine to build so I haven't used it yet but a couple here have and I haven't heard of any such problems.

[Carl H]

gt28rs = teh suck on a rb20 why are you using that turbo, its too small for a 2l....if you are really worried about it remove it completely, its really only there for twin scroll turbos.

[Yellow4g63]

That crack shouldn't hurt anything unless you were running a divided turbine housing turbo. My friends was cracked too must be a common thing with them.

[Yellow4g63]

BTW what cam gears are those?

[StricNyne]

look like fidanza

[BoostFab]

that crack should be ok, keep your eyes on it if it cracks through the outside, then you'll have an exhaust leak....which results to turbo lag

[slow s13]

whats the biggest garrett known to fit under this manifold? would a gt3071r fit?

[hazw8st]

Thats a nice manifold...you can actually weld it....

[Sky240PWR]

That crack shouldn't hurt anything unless you were running a divided turbine housing turbo. My friends was cracked too must be a common thing with them.

well I bought this PT67 and HKS manifold and wastgate off a NICO member, I'll have to check and see if it's got a crack too!..............i don't know much about this manifold, is it any good?.....and how much hp can they handle?

Modified by Sky240PWR at 4:50 AM 2/9/2006
Modified by Sky240PWR at 4:50 AM 2/9/2006

[Carl H]

fwiw my gt30r barely clears the hks manifold.

[Need2Boost]

Carlh, it looks like you have more room than I do. I dont know how differently the rb20 and rb25 sits, but my gt35r is very very tight as well. I went with a E compressor as well.

What method did you use to mount the turbo? Put the turbo on after the manifold or together in one peice? Ill get pics of my setup later.

[mello88]

Great response here, thanks for all the input. I'm glad to know I'm not the only one with this divider wall crack!

Carl H, thank you for commenting in my thread, I just wish your post were a little more helpful . This is my first turbo build and I'd really like to hear your input, I've read your posts on this board and others and respect your advice.

I have read a few books and studied SAU and many RB forums for some time for info on my build. My goals for the RB20 are 2-2.2bar with ~300ish rwhp, with a 7500 limit. Motor has adj cam gear, fmic, 3" turbo back, 500cc's, z32 and PFC on stock internals to support this power. Now, if my math is right it looks like the RB20 should flow 30-35lb/min @ 7500rpm with 2-2.2bar.



When I plot the lb/min curve onto the gt28rs comp map it looks like the it will support the flow, and offer a quick spool and nice midrange.

Edit: I forgot to mention that I am also considering the gt2871r and gt2876r, would the 76r be more suitable for my application? Midrange torque and quick spool time are more important to me than peak hp. On the same note, I have no idea which turbine A/R to go with; .64 or .86 -- which do you suggest for the little rb20 on say a 2871 or 2876?

Thanks for your insight
Modified by mello88 at 4:22 PM 2/9/2006

[240Z_Master]

I've got the same crack on my RB manifold

[mello88]

BTW what cam gears are those?

Yeah they are some Fidanza gears I picked up off ebay for $150ish. One of my stock cam gears got a nice hairline crack in it .

BTW Carl H there is another post on here on NICO/RB where you're looking for cam gears. I still have one good stock gear if you need it, lmk.

[Carl H]

BTW Carl H there is another post on here on NICO/RB where you're looking for cam gears. I still have one good stock gear if you need it, lmk.

lol, i was proly looking for adjustable ones, no worries tho ive got greddy gears now and couldnt be happier.

[Yellow4g63]

well I bought this PT67 and HKS manifold and wastgate off a NICO member, I'll have to check and see if it's got a crack too!..............i don't know much about this manifold, is it any good?.....and how much hp can they handle?

Modified by Sky240PWR at 4:50 AM 2/9/2006

Modified by Sky240PWR at 4:50 AM 2/9/2006

I was going to run that manifold, but then I wanted something much more If I wasn't getting a Equal Length Stainless steel manifold made I would have ran the HKS. That crack in the collector isn't a problem tho. On my friends it didn't even come close to making it to the outside of the manifold.

[mello88]

CarlH what timing are you running on your cam gears? Also what are your opinons of 2876r or 2871r on rb20? .64 AR

Thanks for the info guys

[Carl H]

CarlH what timing are you running on your cam gears? Also what are your opinons of 2876r or 2871r on rb20? .64 AR

Thanks for the info guys

i had my cam gears set to 0* when my car was running, however im going to properly degree my cams when i put the old girl back together for the most gains to be had from the cams.as far as turbo sizing goes get a hold of blake (seva-s13?) on this fourm he knows more about turbo sizing and what works and what doesnt.