RHD RB30 Build - update 6/20/13

Discuss the RB20, RB25 and RB26 series engines.
julio
Posts: 374
Joined: Fri Oct 06, 2006 1:18 pm
Car: RB26 AWD converted S14

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Whats the wastegate pressure with the boost controller off? Could be that your wastegate spring is too weak and you need to increase it. I'm sure that big turbo needs all the exhaust it can get to make boost.


J2fast
Posts: 226
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Car: 240sx
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julio wrote:Whats the wastegate pressure with the boost controller off? Could be that your wastegate spring is too weak and you need to increase it. I'm sure that big turbo needs all the exhaust it can get to make boost.
it makes 19-20psi with no boost controller on it.

RRRRB
Posts: 758
Joined: Wed Jun 01, 2011 9:31 am
Car: 98 RB powered S14
Location: WA

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take the lines off the wastegates let them stay shut the entire time, boost on it higher up in the rpm range and see if it makes more boost..

boostedh23a1
Posts: 281
Joined: Tue Oct 17, 2006 1:37 pm
Car: Datsun 240Z
Datsun 280Z
Location: Beaufort, SC

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I am running the R230 with the 4:11 richmond gears. It was nice on the rb26 but with the rb30 you really gotta petal it alot more to keep from shredding the tires. Then again with the 3.69 gears i was pretty much never coming out of 2nd gear in town. haha.

J2fast
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RRRRB wrote:take the lines off the wastegates let them stay shut the entire time, boost on it higher up in the rpm range and see if it makes more boost..
when i took the lines off the wastegate it only boost about 18-19psi.

RRRRB
Posts: 758
Joined: Wed Jun 01, 2011 9:31 am
Car: 98 RB powered S14
Location: WA

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i mean all the lines.. so there are none going to it

julio
Posts: 374
Joined: Fri Oct 06, 2006 1:18 pm
Car: RB26 AWD converted S14

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J2fast wrote:
RRRRB wrote:take the lines off the wastegates let them stay shut the entire time, boost on it higher up in the rpm range and see if it makes more boost..
when i took the lines off the wastegate it only boost about 18-19psi.
Are you saying 18-19psi with no lines hooked up to the wastegate or just bypassing the boostcontroller?

J2fast
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Are you saying 18-19psi with no lines hooked up to the wastegate or just bypassing the boostcontroller?[/quote]

well when i didnt have any lines in the wastegate it was about 15-17psi with the lines hooked up but controller off it gets 18-19psi

julio
Posts: 374
Joined: Fri Oct 06, 2006 1:18 pm
Car: RB26 AWD converted S14

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Julio wrote:Are you saying 18-19psi with no lines hooked up to the wastegate or just bypassing the boostcontroller?
J2fast wrote:well when i didnt have any lines in the wastegate it was about 15-17psi with the lines hooked up but controller off it gets 18-19psi
Unless you have the top port hooked up, there is no reason why it should boost more with the lines hooked up vs. not. Considering your car only boosts 15-17psi with no lines attached at all (where it should over-boost to 30-40+psi), I would say you are missing the fire ring, loose v-band clamp/blown WG gasket, or have a very, very, very weak wastegate spring.

J2fast
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Unless you have the top port hooked up, there is no reason why it should boost more with the lines hooked up vs. not. Considering your car only boosts 15-17psi with no lines attached at all (where it should over-boost to 30-40+psi), I would say you are missing the fire ring, loose v-band clamp/blown WG gasket, or have a very, very, very weak wastegate spring.[/quote]

whats the fire ring? its a v-band setup

julio
Posts: 374
Joined: Fri Oct 06, 2006 1:18 pm
Car: RB26 AWD converted S14

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The fire ring slips inside the WG vband flange and serves as the seat for the WG valve. Without it, exhaust would flow out of the wastegate even when not under boost.

J2fast
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julio wrote:The fire ring slips inside the WG vband flange and serves as the seat for the WG valve. Without it, exhaust would flow out of the wastegate even when not under boost.
Oh yea I have that in place. I replaced a dried out hose from the wastegate n now it will go to about 27-28psi but not 30's. when u said that if no lines are hooked up its suppose to over boost right? But how if it only going by spring pressure

RRRRB
Posts: 758
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If there are no lines going to the gates.. there is no pressure there to open it.. the pressure from the turbo has to over come the springs in the gate..

J2fast
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RRRRB wrote:If there are no lines going to the gates.. there is no pressure there to open it.. the pressure from the turbo has to over come the springs in the gate..
But I thought once it hits enough flow that pushes the spring up then that's all it can hold which is why U have to get a boost controller to add boost

RRRRB
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Yes exhaust will eventually open the gates.. but not till very late in the rpm range... generally a 1:1 ratio is normal

J2fast
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RRRRB wrote:Yes exhaust will eventually open the gates.. but not till very late in the rpm range... generally a 1:1 ratio is normal
But if it's like a 20something psi spring in there it wouldn't boost to 30-40psi tho would it

RRRRB
Posts: 758
Joined: Wed Jun 01, 2011 9:31 am
Car: 98 RB powered S14
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Have you ever blew a wastegate line off? Boost generally goes to the moon before it hits boost cut.. hopefully you hav e one set up..

Sounds to me you haven't checked everything thoughly.. a boost leak test would have found your wastegate line leak etc.. your missing something..

J2fast
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RRRRB wrote:Have you ever blew a wastegate line off? Boost generally goes to the moon before it hits boost cut.. hopefully you hav e one set up..

Sounds to me you haven't checked everything thoughly.. a boost leak test would have found your wastegate line leak etc.. your missing something..
I have blown a few off but I just don't get as much boost when mines pop off. N last night I replaced all my vac lines.

julio
Posts: 374
Joined: Fri Oct 06, 2006 1:18 pm
Car: RB26 AWD converted S14

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It sounds like you just need a stiffer WG spring.

J2fast
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julio wrote:It sounds like you just need a stiffer WG spring.
Well I upgraded 3times already but the part that don't make sense is no boost controller it gets 18psi with boost controller max it gets is 27psi

boostedh23a1
Posts: 281
Joined: Tue Oct 17, 2006 1:37 pm
Car: Datsun 240Z
Datsun 280Z
Location: Beaufort, SC

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I would think your controller is maxed out too, unless you have a dual port controller.

J2fast
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so i FINALLY found the problem......... the stupid intake manifold under the bottom has a bunch of air coming out from it at only 7psi on the boost leak tester. so now im going to weld the two pieces together than i shouldnt have this issue again. thanks for all yalls help on brain storming.

RRRRB
Posts: 758
Joined: Wed Jun 01, 2011 9:31 am
Car: 98 RB powered S14
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glad you found it... lets see some numbers on that comp turbo!

Booztd 3
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Don't forget to dial the boost back down, lol

J2fast
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Booztd 3 wrote:Don't forget to dial the boost back down, lol

I know ive been thinking should I change the springs again. But idk I guess I'll see how much it hits first then change it if need be but aiming for 36psi

Booztd 3
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Just setup a fuel cut for a pre-determined boost threshold. Your teeth might meet your steering wheel but at least you'll save your engine.

J2fast
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Booztd 3 wrote:Just setup a fuel cut for a pre-determined boost threshold. Your teeth might meet your steering wheel but at least you'll save your engine.
well i wish PFC had those types of options to control that but......

J2fast
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so a quick update

i took the head off to take it to the machine shop to fix the shims issue and found that th valve guides are bad. how much power is at lost usually? and while its out should i do valve angle job? or anything like that?

RRRRB
Posts: 758
Joined: Wed Jun 01, 2011 9:31 am
Car: 98 RB powered S14
Location: WA

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Why did you pull the head for a shim issue?

Are the valve guides in the head now the original OEM?

I wouldn't mess with the valve seat angles unless the guy doing it knows RB heads and what they like..

Was the head previously ported or modified?

J2fast
Posts: 226
Joined: Sat Sep 12, 2009 3:57 am
Car: 240sx
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RRRRB wrote:Why did you pull the head for a shim issue?

Are the valve guides in the head now the original OEM?

I wouldn't mess with the valve seat angles unless the guy doing it knows RB heads and what they like..

Was the head previously ported or modified?
Well I pulled the head off so they can make the valves perfect. But the guides where original. The head was ported mildly. But was thinking to do any small thing to do why it's out


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