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What I miss for 30psi of boost?

Nabeel

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Jul 14, 2006
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After I made my gvr4 stable on the road. Again I got hungry for more power. So I upgrade to big 16g & 2g ported exhaust manifold, External dumper, 3"exhaust + Methanol & Nitrous kit. I am still more hungry for power. So I am thinking of doing 30psi of boost. My engine is almost stock except the HKS264 Cam. My fuel system should deliver enough fuel as I am using 255 walbro fuel pump, 650fic injector & AEM AFPR. My induction also should deliver enough Air. Using 3g Maf, Cyclone intake & Racing Air filter. I am worried about the engine internal. It may not handle 30psi of boost. What should I change to let it handle that.
 

4thStroke

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The 16g will not hold 30psi. You can get it to spike higher than that, but I'm not sure how well methanol will do to keep knock away.
 

turbowop

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I agree with Spencer.

That said, I run 30psi on stock internals with an FP3052. Only changes to the stock engine are ARP headstuds and an OEM MLS headgasket.
 

Nabeel

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Ok.then ARP headstuds and an OEM MLS headgasket & timing belt stuff at once. This is what I need. Thanx
 

alansupra94

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Quoting turbowop:
I agree with Spencer.

That said, I run 30psi on stock internals with an FP3052. Only changes to the stock engine are ARP headstuds and an OEM MLS headgasket.



Really? Thats quite impressive! From what I have seen most people O-ring the block or head (not sure which one at this point) to help it hold.
 

3rdstrikedsm

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I have never done that much boost on a dsm but have done it on a stock evo 8 31 ps1 held for 2 years and if you want a 16g to hold that psi put a dsm valvespring in the stock internal wastgate this is how the rally cars hold that much boost on tiny stock turbos.
 

turbowop

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Quoting alansupra94:
Quoting turbowop:
I agree with Spencer.

That said, I run 30psi on stock internals with an FP3052. Only changes to the stock engine are ARP headstuds and an OEM MLS headgasket.



Really? Thats quite impressive! From what I have seen most people O-ring the block or head (not sure which one at this point) to help it hold.




Boost isn't what blows up motors, bad tuning is. From '03 to '06 I ran a FPgreen at 28psi on 110 octane. Since then I've been running an FP3052 at 30psi on pumgas/meth. Makes good power and holds up great.
 
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4thStroke

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Quoting 3rdstrikedsm:
I have never done that much boost on a dsm but have done it on a stock evo 8 31 ps1 held for 2 years and if you want a 16g to hold that psi put a dsm valvespring in the stock internal wastgate this is how the rally cars hold that much boost on tiny stock turbos.



I don't think that is going to help the turbo hold 30psi up top. I ran around with the wastegate line pulled and I was only able to hold 25-26psi or so. However, it would spike mid 30s, and I got it to creep 39psi at part throttle. The turbo was ported to creep so we could get as much boost out of it we could. That turbo lived a short life.

Do the restrictors affect the boost on rally cars?
 

turbofonz

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I'd say ARP's and keep the OE composite. ARP L19's if you got the coin. My motor's all stock other than the ARP's, no balance shafts and cams (on my 1g... same thing)

I run 35+ psi spikes on my 1g. It'll hold 30-31 on cooler days.

Don't take this the wrong way, but it sounds like your setup needs to be setup properly first. My 1g is a "strong" 16g car, and I'm sure with a shot of juice would be very brutal.
 

Nabeel

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You mean I don't need to take off the head? Just got the ARP's Bolt on, tight them & run... That will save much other than changing the head gasket.I am hoping that the methanol & 2 step colder plugs will help a lot.
 

4thStroke

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Quoting turbofonz:
I'd say ARP's and keep the OE composite. ARP L19's if you got the coin. My motor's all stock other than the ARP's, no balance shafts and cams (on my 1g... same thing)

I run 35+ psi spikes on my 1g. It'll hold 30-31 on cooler days.

Don't take this the wrong way, but it sounds like your setup needs to be setup properly first. My 1g is a "strong" 16g car, and I'm sure with a shot of juice would be very brutal.



Have you dynod your car?

What fuel are you using? Any methanol?
 

Adorsey

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mass
Quoting Nabeel:
You mean I don't need to take off the head? Just got the ARP's Bolt on, tight them & run... That will save much other than changing the head gasket.I am hoping that the methanol & 2 step colder plugs will help a lot.



Just do them 1 at a time.


But yeah stock motor ftw
 

turbofonz

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Quoting 4thStroke:

Have you dynod your car?

What fuel are you using? Any methanol?



397awhp breaking up BAD at 6900 rpms. Power was dropping before the breakup...It would easily of did low 400's on a clean run I'd assume. Cars' on e85. It's trapped as high as 127.8mph, 2920lbs FWIW. Original bottom end.

Yeah, you can do the ARP's one by one. Just hope your stock headgasket's in good shape. If not, toss another OEM one on.

Some people like MLS's and stuff, but I'm a huge fan of the stocker, that's just me I guess. I haven't had a problem with it.
 
Last edited:

talon

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Sep 3, 2009
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Denham Springs, La
If I'm not mistaken, a big 16g is only good to about 25 psi. The only advantage of a big 16g over a small, is the b16g is able to build boost at higher rpm's, so its a mid-high range turbo. The small 16g is more of a low-mid range turbo.

With your fuel setup this is what I calculated.

The 16g is capable of:
520 cfm / 38 lb/min / 25 psi

650cc @ 100% IDC will support 37.32lbs/min

Walbro 255 (plug n play)
25psi = 49.97lbs/min

Walbro 255 (rewired)
25psi = 59.58lbs/min

You can clearly see that not only can your turbo not support 30 psi, neither can your injectors.
 

cheekychimp

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Quoting turbowop:
I agree with Spencer.

That said, I run 30psi on stock internals with an FP3052. Only changes to the stock engine are ARP headstuds and an OEM MLS headgasket.



Yeah but you are running a lot more injector Mark. I don't think that the OPs fuel system is enough to support 30 psi even if it is a smaller turbo. As for the big 16G being a mid to high range turbo, I also disagree. If I recall correctly it flows only marginally more than the small 16G at the very top of the rpm range and is less efficient everywhere else in the map. I have always been told that a small 16G is an evolution of the big 16G and a much better turbo and if you are willing to give up a tiny bit of spool for more power you should just forget about the big 16G and step up to the EVO III.
 
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turbowop

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I was only adding a data point about what a stock motor can handle. I wasn't trying to imply that his fuel system is up to the task.
 

cheekychimp

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Yeah I know, I just didn't want to let that go because I think running 30 psi on 650's could end in tears, even with the meth kit.
 

turbowop

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I haven't done the math, but when running meth you can go smaller in injector size since the fuel can be leaned way out as meth starts spraying. I have way more injector than I need now on my setup at 950's.
 

cheekychimp

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Maybe there is hope then. I thought the 850s I bought were going to be too small but I've yet to get that far and start messing with the meth injection, maybe I'll be okay.
 

the big 16g will not be doing anything at that boost level. Just because your boost gauge reads 30 psi doesn't really mean anything at all. Like posted above the turbo is only going to flow properly up to 25-26 psi after that its not going to really do anything.

If you run those injectors, even with meth there is no room for adjustment and daily driving really wont be an option at all. The motor internally will take anything you throw at it. My buddy ran a gt35r on 35 psi for almost 2 years without an internal problem. /ubbthreads/images/graemlins/worthy.gif

Instead of building things just buy a bigger turbo and run a little less boost 25-28 psi. Run an sc61 or something 35r wheel optioned and make 450hp no problem and no meth on 93 octane. /ubbthreads/images/graemlins/jawdrop.gif
 
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