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turbo size/boost

This is a discussion on turbo size/boost within the Forced Induction forums, part of the LSx Technical Help Section category; well with that being said, im looking for good power from 3000 on up. with 70mm or larger compressor. what ...

  1. #21
    Member JAX04's Avatar
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    PBM 366ci TC78 E85
    2004 Pontiac GTO PBM A4

    well with that being said, im looking for good power from 3000 on up. with 70mm or larger compressor. what would suggest

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    dpends on your budget. look into the MP series of turbos. good numbers for a low price. they sell the 70 and the 76mm from MP...master power. i both are like 600 and 650

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    PBM 366ci TC78 E85
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    yeah i was looking at those. they dont sell the .81 on the hotside though they only have the .96. ihave been toold for the rearmount that that would take awhile to spool

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    Quote Originally Posted by JAX04 View Post
    yeah i was looking at those. they dont sell the .81 on the hotside though they only have the .96. ihave been toold for the rearmount that that would take awhile to spool
    look up zombie on ls1tech. he runs a big AR on the buttmount turbos. i think his is 1.08 on a 80mm

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    PBM 366ci TC78 E85
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    huh, thats weird. thas why i just need to go with the old trial and error. everyone says something different. i dont know. ill check him out

  6. #26
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    PBM 366ci TC78 E85
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    i just wanted to point out, the reason he is haveing success with that setup is becuase he put a valve in the hotside inlet that chokes down the flow below 10psi in the exhaust so that you have a v8 pushing exhasut throught the size of a t2 pr t3 housing. then when the preassure becomes to mch (10psi) the gate swings open and bam now you have a turbo thats already spooled up. it will only work on turbos with a split hotside, and its pointless unless you want a 750-1000 hp car. just did alot of reading

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    well i said take alook i didnt say it was all that right. his car with proper mods would be a mid 9s ride

    valve is a good idea

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    Quote Originally Posted by Quik View Post
    im actually curious to why you think 5-7 psi is max. there are quite a few ppl pushing double those numbers for thousand of miles. as for your statement on something has to give with power. forged or not doesnt matter if its going to fail its going to fail. Im not saying dont buy forged but fact is either material the can fail. Fastest LSX street car been running a stock crank for years and daily drives the car. has to say somehting.

    ppl think just cause your vehicle makes X amount of power its going to die within a X amount of mileage. Fact is, its how its treated and used will determine the life of it. you can have 1K hp vehicle, that doesnt mean push 1k hp everytime you go to take it out

    Well, it's really simple. First, these motors were intended to run in the 300hp range from the factory. And, with routine maintenance and such you can expect the thing to live well past the 100k mile mark. But, we start playing with it and adding things to them and the power goes up and the parts wear and tear a lot faster. Now, I'm not sure what you consider the "fasted LSX street car" but I assure you, there is one in Ohio that runs 7's and they drove the thing to the track. It's titled, and can be street driven but I assure you it doesn't have a stock crank. And I promise you that they dont expect it to last 100k miles. Stock cranks are great, dont get me wrong, but they were designed with a 500hp mark in mind I believe by GM with reliablity in mind. I'm not saying that there aren't cars out there with stock cranks over 1K HP. I'm sure they are. But I assure you they aren't going to last 50K miles. And the thought of "well we dont always drive them hard" doesn't play in that much. Lets face it, every time we get behind the wheel we aren't driving it to just say "wow, I have 1K hp but I'm only going to the grocery store so I'll take it easy."

    If you want to keep the "daily driven" status of the car and maintain some reliablity then 5-7 lbs of boost is about it.

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    Quote Originally Posted by cailey37 View Post
    Well, it's really simple. First, these motors were intended to run in the 300hp range from the factory. And, with routine maintenance and such you can expect the thing to live well past the 100k mile mark. But, we start playing with it and adding things to them and the power goes up and the parts wear and tear a lot faster. Now, I'm not sure what you consider the "fasted LSX street car" but I assure you, there is one in Ohio that runs 7's and they drove the thing to the track. It's titled, and can be street driven but I assure you it doesn't have a stock crank. And I promise you that they dont expect it to last 100k miles. Stock cranks are great, dont get me wrong, but they were designed with a 500hp mark in mind I believe by GM with reliablity in mind. I'm not saying that there aren't cars out there with stock cranks over 1K HP. I'm sure they are. But I assure you they aren't going to last 50K miles. And the thought of "well we dont always drive them hard" doesn't play in that much. Lets face it, every time we get behind the wheel we aren't driving it to just say "wow, I have 1K hp but I'm only going to the grocery store so I'll take it easy."

    If you want to keep the "daily driven" status of the car and maintain some reliablity then 5-7 lbs of boost is about it.
    Fastest LSX car is a class in the LSX shootout in memphis. its part of the NMCA. Mightymouse past 2 yrs won this, full weight TA weighing in around 3900lbs goes 8.7s on 17s and DRs

    you stick with 7lbs of boost and let others decide on what they want.

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    Quote Originally Posted by Quik View Post
    Fastest LSX car is a class in the LSX shootout in memphis. its part of the NMCA. Mightymouse past 2 yrs won this, full weight TA weighing in around 3900lbs goes 8.7s on 17s and DRs

    you stick with 7lbs of boost and let others decide on what they want.
    First, David Childress, Mightymouse, doesn't expect his car to last that long. And if I remember correctly I believe he was rebuilding it not long after the shootout. I think you are missing the point. The question was what can the stock crank safely take. It can't safely take no 20lbs. I dont run 7lbs in my car but I also know that it's not going to last no 5 years. You get guys come on here and start telling people that you can safely run 10-15-20lbs and forget to tell the rest of the story.....a trail of broken parts and a lot of grief. Why dont you talk to David....he'll be glad to tell you his story....

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    grand poobha james schofield's Avatar
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    Quote Originally Posted by cailey37 View Post
    First, David Childress, Mightymouse, doesn't expect his car to last that long. And if I remember correctly I believe he was rebuilding it not long after the shootout. I think you are missing the point. The question was what can the stock crank safely take. It can't safely take no 20lbs. I dont run 7lbs in my car but I also know that it's not going to last no 5 years. You get guys come on here and start telling people that you can safely run 10-15-20lbs and forget to tell the rest of the story.....a trail of broken parts and a lot of grief. Why dont you talk to David....he'll be glad to tell you his story....
    so back to my question what is a good setup? .70 .78?? or be a safe .60? not trying to turn the world with power, just looking for a little more. 5-8 psi what all is needed as far as the fuel system?
    pump or pumps or will the stock pump work?
    injectors?

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    Quote Originally Posted by cailey37 View Post
    First, David Childress, Mightymouse, doesn't expect his car to last that long. And if I remember correctly I believe he was rebuilding it not long after the shootout. I think you are missing the point. The question was what can the stock crank safely take. It can't safely take no 20lbs. I dont run 7lbs in my car but I also know that it's not going to last no 5 years. You get guys come on here and start telling people that you can safely run 10-15-20lbs and forget to tell the rest of the story.....a trail of broken parts and a lot of grief. Why dont you talk to David....he'll be glad to tell you his story....
    his motor was upgraded yes. when you make power dont expect your motor to be a 50k mile setup. once you start making that kind of power you dont DD your ride anymore and its now a toy. Fact is stock crank has held up plenty. I believe Ohio boys ran stock crank for some time. KP or KB ran stock crank and was a solid low 9 high 8s car. the crank isnt a weak link as the old SBC were. If someoen wanted their car to truely last 100k leave it alone with bolt ons. once you decide to crank on a motor it should be maintained often. with that being said go down the fastest FI list on LS1tech and see how many run the stock cranks

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    Quote Originally Posted by james schofield View Post
    so back to my question what is a good setup? .70 .78?? or be a safe .60? not trying to turn the world with power, just looking for a little more. 5-8 psi what all is needed as far as the fuel system?
    pump or pumps or will the stock pump work?
    injectors?
    Psi is a measurement of restriction.. 5psi on this combo isnt the same as 5psi on that setup. so Psi figures are illrevliant.

    stock fuel lines will work for up till about 700hp. if you only want 500 rwhp 1 walboro 255 is enough. if you want more power twin walboros. 70mm if you only want about 600 rwhp

    injectors look into 60s

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    Quote Originally Posted by james schofield View Post
    so back to my question what is a good setup? .70 .78?? or be a safe .60? not trying to turn the world with power, just looking for a little more. 5-8 psi what all is needed as far as the fuel system?
    pump or pumps or will the stock pump work?
    injectors?
    I'd say go with a 76mm turbo...upgrade the pump and injectors and run that until you decide to go further. The stock pump and injectors wont do the job I'm afraid. It would be pushing the injectors. You could run 5-8lbs and have great volumetric efficiency with it. As far as the a/r, I dont remember what you said as far as your set up goes......auto/manual??? where do you want the powerband????

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    i agree, t76 with a .81 a/r. turbonetics. would be great.

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    PBM 366ci TC78 E85
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    before when i asked at the top of the page was just to prove a point. thats all

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    grand poobha james schofield's Avatar
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    Quote Originally Posted by cailey37 View Post
    I'd say go with a 76mm turbo...upgrade the pump and injectors and run that until you decide to go further. The stock pump and injectors wont do the job I'm afraid. It would be pushing the injectors. You could run 5-8lbs and have great volumetric efficiency with it. As far as the a/r, I dont remember what you said as far as your set up goes......auto/manual??? where do you want the powerband????
    manual, 2500-5800 rpm power band, what is A/R actually? is the walbro pump an intank or inline pump? external regulator im guessing? the cam is 219 227 113

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    the a/r is a ratio that describes the distance from the center of the turbine to the hole where the exhaust enters in realtionship to the total area of the snail its self. i think, im probably wrong. think of this. .68 .70 .81 .96 1.0 1.15. the bigger the number get the bigger the hotside is. and the longer it will take to spool. if you search a/r in google bar a/r as it refers to a turbo. im sure youll find a good read up. thats what i did.

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    Quote Originally Posted by JAX04 View Post
    the a/r is a ratio that describes the distance from the center of the turbine to the hole where the exhaust enters in realtionship to the total area of the snail its self. i think, im probably wrong. think of this. .68 .70 .81 .96 1.0 1.15. the bigger the number get the bigger the hotside is. and the longer it will take to spool. if you search a/r in google bar a/r as it refers to a turbo. im sure youll find a good read up. thats what i did.
    thanks for schooling me .

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    Quote Originally Posted by JAX04 View Post
    the a/r is a ratio that describes the distance from the center of the turbine to the hole where the exhaust enters in realtionship to the total area of the snail its self. i think, im probably wrong. think of this. .68 .70 .81 .96 1.0 1.15. the bigger the number get the bigger the hotside is. and the longer it will take to spool. if you search a/r in google bar a/r as it refers to a turbo. im sure youll find a good read up. thats what i did.
    the time of spool also depends on size of turbo. a 60mm will spool faster then a 80mm on same size motor. the AR also reflects when turbo will start to choke. you have to take the whole equation as solid factor. you cant just say this AR will do this. you can say this compressor will do that either.

    inline pumps are a bandaid. youll want a intank pump

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