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Discussion Starter #1
I KNOE THAT THE SRT4 IS BOOSTING 14.5PSI STOCK, IF YOU PUT A BOOST CONTROLLER HOW MANY MORE PSI CAN YOU CRANK IT UP.IN OTHER WORDS WHATS THE MAX BOOST IT CAN HANDLE WITH THE STOCK INTERNALS???
 

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Remember one thing though, that with every action comes an equal and opposite reaction. You can't just dial in more boost for shits and giggles.

#1 Dialing in more boost will raise the compression ratio (at certain points that is)

#2 This will cause knocking at certain engine speeds because of excess heat in the combustion chamber. This is called detonation. (you'd need higher octane gasoline to counteract this)

#3 This could kill your engine internals
 

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Forged rods, cast pistons. I don't know much about the block 'cause this is my first Ne- . . . SRT-4. :oops: Cast pistons are okay for more boost IF you are very, very careful and add fuel as required, but they are unforgiving if you make a mistake. If you want to boost up into the mid 20's or more you'd best get forged pistons which can handle the heat and a little detonation better. DO NOT use hypereutectic pistons in a turbo engine!
 

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Mike B. said:
Forged rods, cast pistons. I don't know much about the block 'cause this is my first Ne- . . . SRT-4. :oops: Cast pistons are okay for more boost IF you are very, very careful and add fuel as required, but they are unforgiving if you make a mistake. If you want to boost up into the mid 20's or more you'd best get forged pistons which can handle the heat and a little detonation better. DO NOT use hypereutectic pistons in a turbo engine!
Mike,

What do you think our cars have, yup Hypereutectic pistons not forged.

:)

Stock boost is not 14.5 psi per say. It will peak to that then drop back down to 11-12psi. With a boost controller, you can set it so it holds the 15psi and peaks at 16.
 

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Did I read that in the FSM? I remember seeing "cast" but not "hypereutectic." Hypereutectics are very intolerant of detonation. They shatter like glass. Why would they (DCX) do that?
 

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Hyperteuretic(as misspelled as the others) is about as close to forged as you can get. They don't suffer as much heat expansion as forged (but they do still expand/contract) and they can withstand nearly as much heat. However, they are brittle in the sense that they don't like the impacts of detonation. They are a good fit in a stock SRT-4 engine though, the car keeps pretty good track of detonation inducing conditions and tries pretty hard to avoid it.

They are a good compromise, balancing cost against function, for a $20,000 car.

Okay, I admit it, I'm just trying to get the post count up so I can be a real ricer, out of the training stage....

Dale
 

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Here's a more direct answer to your question. In my opinion, I feel that the stock SRT-4 should not be tuned above 16psi unless you have done a few other modifications such as fuel. Please keep in mind, if you are using a manual boost controller, to set it where it does not spike above 16psi. This may require you set the maximum boost at 14-15psi.

Just my opinion, but a safe one..... :wink:

-Sam
 

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Exhaust Depot said:
What do you think our cars have, yup Hypereutectic pistons not forged.
Okay, Hector, I'm going to have to call you on this one and ask you where you got that information. I got home from work and looked in the FSM and I can't find the word "hypereutectic" anywhere in it. On page 9-45 it says, "The pistons are made of a cast aluminum alloy. The pistons have full floating pins attached to forged steel connecting rods."
 

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I wouldnt want to go above 15psi at the moment as the car only has a 1 bar MAP sensor.

To ExhaustDepot:
How have you gotten the car to run 15psi consistently?
Have you removed the stock sontrol over the boost pressure and then added your boost controller?
Do you see the boost pressure falling off at higher RPMS(a sure sign of too small of a stock turbo running out of flow, ex. 2nd gen DSM T25)?
 

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alot of SRT owners down here in south fla are boostin 17-19 psi. i don't hear any knock or anythang. I also checked tha plugs and they looked fine. My profec is only goin up to 19 now for some odd reason, ill have to look over the way i have it hooked up and play w/ it. When i dyno this comming week, ill see what tha a/f is at 19 psi.
 

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A tidbit for discusion:

Stage 2 includes bigger injectors and a 2 bar MAF sensor. 8)
Stage 3 includes even bigger injectors and a 3 bar sensor. :twisted:

Thats a lot of boost.

However, I have been hearing persistant rumers of head issues, and problems around 300 hp. Thats fine by me, FWD, 300hp and auto-x turns don't play well together anyway.
 

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Mike B. said:
Exhaust Depot said:
What do you think our cars have, yup Hypereutectic pistons not forged.
Okay, Hector, I'm going to have to call you on this one and ask you where you got that information. I got home from work and looked in the FSM and I can't find the word "hypereutectic" anywhere in it. On page 9-45 it says, "The pistons are made of a cast aluminum alloy. The pistons have full floating pins attached to forged steel connecting rods."
True, you won't find "hypereutectic" in the FSM, it's not a real word. You probably won't find Hyperturetic (equally misspelled I'm sure) either, as "cast aluminum alloy" is what they are made of, with hyperturetic being a process applied to the cast piston. First and second gen pistons are also hyperturetic, yet are listed as cast aluminum alloy in the FSM.

Not as good as forged, not as bad as honda.... ohh, I'm gonna burn for that one...
 

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The winter 2003 Mopar Now! says...

(for what it's worth...)

"The bottom end is plenty strong, with forged connecting rods, and top-quality hypereutectic cast pistons with full-floating pins making up the reciprocating assembly..."
 

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abaddsm said:
I wouldnt want to go above 15psi at the moment as the car only has a 1 bar MAP sensor.
Boy that would sure suck if it were true. A 1 bar map sensor measures one bar, as in zero boost. 1 bar map sensors are used in non boosted engines. According to the chat transcript the car has a 2.25bar sensor stock, meaning theoretically the maximum it will read is 18.375psi.
el_jefe said:
A tidbit for discusion:
Stage 2 includes bigger injectors and a 2 bar MAF sensor. 8)
Stage 3 includes even bigger injectors and a 3 bar sensor. :twisted:
Not quite, according to the pics from SEMA the stage II includes a 2.5 bar and the stage III includes a 3 bar, so theoretically they will read 22.05psi, and 29.4psi. Also the car has a MAP sensor, not a MAF sensor. MAF sensors don't care about or measure pressure, just airflow so they aren't rated in bar. (el_jefe, I know you probably know that and it was a typo, just adding info for those who don't know.)

Back to the original subject, I don't think we know what the engine will handle with the stock turbo. My *guess* is that the turbo efficiency drops off pretty badly at a few psi above stock so you will get more heat, and increased chance of detonation. Until we know more about the limits anyone trying to push the stock turbo to 18psi or more needs to be careful. (Or not, go ahead and blow an engine so the rest of us will know when enough is enough on the stock turbo :wink: )

Unless MOPAR completely changes their plans we know that with the proper turbo and electronics the stock engine will handle at least 300hp.
 

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the stages also come with new TIP sensors also.
 
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