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Old 11-26-2005, 05:24 PM   #1
PSI87
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Default 2.5rs block

Hey I have a 98 Subi 2.5 rs. The motor is pretty much built, but how much power can the block take?
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Old 11-26-2005, 06:46 PM   #2
NeaD
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hummm... more info?
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Old 11-26-2005, 11:50 PM   #3
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As in built, different pistons, rods?
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Old 11-27-2005, 01:08 AM   #4
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since every "built" motor is the same and "pretty much" means the same thing for every situation...id say if you use more than 1 psi'z of b00st but less than 50, youre in the danger zone
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Old 11-27-2005, 01:21 AM   #5
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he is obviously running 87psi, DUH. Which by reverse calculating the tensile stress on the cylinder walls divided by the universal constant of alex's man package=blown motor.

in all seriousness though we need more info, do you just mean the block itself, you will not blow out a cylinder wall before you blow a rod or ring or piston IMO.
Ben
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Old 11-27-2005, 01:54 AM   #6
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Well, I know the motor has JE pistons. Either stock rods or slightly larger. I was just curious about the block its self.
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Old 11-27-2005, 03:23 AM   #7
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The block is usually not the problem - the rods, the rings or the gasket would have given up first. So from that I would say 7psi on stock fuel
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Old 11-27-2005, 04:25 AM   #8
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Quote:
Originally Posted by kgb
The block is usually not the problem - the rods, the rings or the gasket would have given up first. So from that I would say 7psi on stock fuel
we just put 96lbs injectors in and it has 2 fuel pumps. This thing should be able to take whatever I throw at it. The blockwas my only concern, that and the tranny but thats anouther story.
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Old 11-27-2005, 04:40 AM   #9
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What do you plan on throwing at it with two fuel pumps and injectors that weigh more than my dog?

-Brett
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Old 11-27-2005, 04:50 AM   #10
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Here in Australia we dont get a 2.5sti so if we want turbo 2.5 we have to use the non turbo 2.5L block like you are talking about.
Anyone that uses these blocks has to strengthen the top of the cylinders to stop them from moving. There are variations in what can be done. Some convert them to fully closed deck and some fit dowels between the bores and the outer case.
Without strengthening the block you will suffer from leaking cylinders. It wont go boom or crack but you'll have trouble sealing the cylinders.
But after thats done there are guys here running sub 11s 1/4 miles without a problem so the block is capable of good hp.
As for an exact hp number or boost number that the standard block starts to leak its hard to say as it can depend on your tune and timing.
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Old 11-27-2005, 12:28 PM   #11
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Quote:
Originally Posted by ScoobaruRS
What do you plan on throwing at it with two fuel pumps and injectors that weigh more than my dog?

-Brett
I bought the car with the 2 pumps and 75lb injectors. The injectors went out and I just replaced them with 96. Id like to get 500awhp out of my current setup, but im not sure thats possible.
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Old 11-27-2005, 03:57 PM   #12
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Ok, first, figure out the CR of the pistons.

Random guessing leads me to 8.5:1. Now, since it's a 98 and has headgasket problems anyway, make sure you do as the aussie told you. Also, what turbo setup are you using? intercooler? etc.

WE NEED MORE INFORMATION!!!!
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Old 11-27-2005, 06:00 PM   #13
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OK, so based on the knowlege that you bought the car used, and based on what you've said was done to the car, we can assume there is a good chance it could have been a former member of this board who owned the car previously. If so, do you know who?

Regardless, one doesn't just replace the internals with JE forged pistons without doing other work to the car. So, do you mind telling us what else you KNOW has been done to the car? Is it already running a turbo (I would hope if the previous owner bothered to drop JE pistons in it). What is the new CR? Is the stroke still the same? Was the block strengthened and/or converted to a closed deck or semi-closed deck?

What IS done, and what do you PLAN to do?

This will help immensely.
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Old 11-28-2005, 01:54 AM   #14
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Quote:
Originally Posted by Brady
OK, so based on the knowlege that you bought the car used, and based on what you've said was done to the car, we can assume there is a good chance it could have been a former member of this board who owned the car previously. If so, do you know who?

Regardless, one doesn't just replace the internals with JE forged pistons without doing other work to the car. So, do you mind telling us what else you KNOW has been done to the car? Is it already running a turbo (I would hope if the previous owner bothered to drop JE pistons in it). What is the new CR? Is the stroke still the same? Was the block strengthened and/or converted to a closed deck or semi-closed deck?

What IS done, and what do you PLAN to do?

This will help immensely.
Oh how I wish i could tell you. Im not sure whats done. I dont think the previous owner knew either. His name is Henry Cox. He didnt do the work, but I have all the recipets. Unfortunantly the recepts dont go into enough detail about this. What I know is it has 8.5:1 pistons and orginal rods .25mm over size. Other than that, I really dont know about the motor itself. It has a large bar fin FMIC and a t3/t4 turbo. The turbo is probably blown, its quite laggy. I intend on replacing it with a 3071. It has a tec3r standalone and various other components you would find in a typical turbo 2.5rs. This guy got pretty serious about the car. All the recepts add up to around 50k. It has little things like a oil cooler kit, racing radiator and aluminum skidplates. That sort of thing gives me a little more confidence about the motor being done right. I hope so at least.
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Old 11-28-2005, 02:01 AM   #15
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you didnt get this from colorado did you?

Ben
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Old 11-28-2005, 02:06 AM   #16
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If it's got 8.5:1 pistons in it, then put on your knock sensor and start at 10 pounds of boost and take her up in 2 lb incramintes in 3rd or 4th until she knocks, retard some timing, see how it does.

Anyways, basically tune it and find out.

I suppose 250+ at the wheels, 500whp sounds ridicoulus, but if you dont care about the longevity of your setup its probably possible with a garret 35r turbo or something.
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Old 11-28-2005, 02:12 AM   #17
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+1 for 500whp with GT35R
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Old 11-28-2005, 02:16 AM   #18
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A customer of Rallitek just rebuilt his 2.5 RS block with STI internals and turbo setup. We will see how it goes.....
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Old 11-28-2005, 03:38 AM   #19
PSI87
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Quote:
Originally Posted by Sko
If it's got 8.5:1 pistons in it, then put on your knock sensor and start at 10 pounds of boost and take her up in 2 lb incramintes in 3rd or 4th until she knocks, retard some timing, see how it does.

Anyways, basically tune it and find out.

I suppose 250+ at the wheels, 500whp sounds ridicoulus, but if you dont care about the longevity of your setup its probably possible with a garret 35r turbo or something.
it already dynoed a lil over 300awhp @ 14psi and its at 19 now.
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Old 11-28-2005, 11:13 AM   #20
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any knock or bad signs at either psi?
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Old 11-28-2005, 03:45 PM   #21
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Quote:
Originally Posted by Sko
any knock or bad signs at either psi?
it did act up a little at 19psi. Let me rephrase that. I was racing, and everything was perfect, until 100mph, a lil more than halfway through 4th gear, then it made a odd noise and stopped pulling as hard as it should. Im hoping it may have just been spark blowout.
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Old 11-28-2005, 03:56 PM   #22
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let me guess, you have had it tuned for 14psi, and you turned it up to 19psi.

Ben
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Old 11-28-2005, 08:05 PM   #23
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i was told its a boost dependent map. It actually has better air fuels at 19.
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Old 11-28-2005, 11:05 PM   #24
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W0Wz4Z!?!
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