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Is it how much PSI or how much HP stock block can take.. different size turbos.!

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Old Jun 24, 2003 | 10:09 PM
  #2  
Dr.Boost's Avatar
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Default Re:Is it how much PSI or how much HP stock block can take.. different size turbo

Q.Now get a hugh striaght T4 truck turbo and run it at 7psi,... what hp gain will you get?? doesn't the T4 give more CFM thus more hp/PSI?
A.Yes. The T4 will flow more CFM leading to a bigger gain in hp.

Q. like if i have an ultra small turbo that gives me 20hp at 70psi, so does that mean i need to run at that high PSI?
A.You will never see 70psi. :P That turbo will crap out at high psi because it can't flow enough CFM. At say 15 psi the difference between 8 psi will be small since it cannot flow the CFM. The only real difference would be the extra unwanted heat in the intake air.

Q.Is our stock internals related to WHP or PSI or CFM?
A.Ummmm...this really depends on how well it is tuned, the condition of the motor, the psi you are running, the size of the turbo, and how efficient the IC is. Basicaly it will depend on horsepower. My tiny rods on my D15 are said to be safe up to ~210~hp. Extra psi will cause extra stress on the cylinder walls, extra horsepower will cause stress on the rods/pistons.

You could safley reach your goal of 170hp if the psi is within a safe range and it is tuned right.


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Old Jun 24, 2003 | 10:53 PM
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Dr.Boost's Avatar
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Default Re:Is it how much PSI or how much HP stock block can take.. different size turbo

ya so if my RHB5 needs 15psi to gain 170whp, it's bad compared to something with 8psi to get 170whp am i right?
Correct.

It would be great to get 170hp out of only 5 psi, but unlikely. The lower the psi the safer you will be.
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Old Jun 25, 2003 | 10:15 AM
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88crxSi's Avatar
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Default Re:Is it how much PSI or how much HP stock block can take.. different size turbo

its never a question of how much psi can my engine handle. in stock trim its not like u can be running 7psi then spike to 7.5 and blow up. It's all about control and the more psi u get in there the more precise control u need. Things have to be put into perspective. There are limits. Like I would never run 20psi on a stock d16. wouldnt last long. 10-12 is probably the highest u could go w/o changin internals. 5-8 is usually what people run. more towards 8 because 5 doesnt increase hp much.
Old Jun 25, 2003 | 10:15 AM
  #9  
Todd's Avatar
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Default Re:Is it how much PSI or how much HP stock block can take.. different size turbo

DR boost your not entirely correct about the T4 question. A smaller turbo and a huge turbo running the same psi (amount of air flow restriced by the engine) will make about the same power. The only way to tell which one will make more is to see which one is more efficient at the airflow you have. Bigger does not always mean more hp at the same pressure level. The trick is to find the compressor size that best fits your engine. That will make the most power at the boost pressure you decide you want to run.
Old Jun 25, 2003 | 01:02 PM
  #10  
ZexRex's Avatar
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Default Re:Is it how much PSI or how much HP stock block can take.. different size turbo

the question about how much psi can my engine handle.. its not psi, its how much hp can it take. if you have it dyno tuned with good fuel management and a wideband a stock dseries can take 200-250 hp daily or 300 (jan style – reliable but wouldn’t be the best daily driver). its all about tuning.

you can relate hp to psi by figuring in what size turbo at what cfm.

example:
BoostedED9
d16a6 - t3t04e 50trim .60/.63 ar, stage 3 wheel
302hp 251tq @ 16.5 psi

now i cant find a dyno of a d16a6 with a smaller turbo like a tdo5h or rhb5 but at that psi they will make less horsepower. i would guess 240-250ish. they will also be less efficient at that psi. if you compared them both at 10psi you would see the difference.

also these turbos have different purposes.. i am talking about peak hp, ie drag racing. if you want a car for rally or road race you want to spool before 4500rpm. but for drag you will never be in that rpm range.



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