how much boost on stock lq9
01-31-2014, 08:20 PM
#1
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how much boost on stock lq9 almost got my lq9 in my car, now im thinking i will go turbo on a carb 6010 setup.. just wondering how much boost a stock bottom end with handle?? if anyone knows, it sure would help me out alot, thanks in advance
02-01-2014, 04:49 PM
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I put 13 psi on a stock bottom end 305 sbc ... so therfore I know it will handle at least 13 psi... just wondering if anyone knows the limit on a lq9... didnt ask about horsepower
02-01-2014, 04:55 PM
#4
You're not getting the point. Boost doesn't equal power. The stock block can handle 50 PSI as long as that doesn't equate to enough power to break the rods. Boost has nothing to do with it. The block doesn't 'sense' that too much boost is being forced into it and decide to blow up. Its a combination of power/torque/rpm that causes them to give out (assuming detonation isn't the issue), and since boost doesn't equal any of these figures on any sort of linear scale, its completely irrelevant.
A tiny turbo forcing air through unported heads on a stock cam and intake with no intercooler might make 600 HP at 23 PSI and ~5600 rpm and the block live forever. Take the same bottom end, put on ported LS3 heads, a Holley Hi-Ram, a custom grind turbo cam, A2W Intercooler, methanol, and a large billet 88mm, and the bottom end blows apart at 18 PSI at 6400 RPM.
There are literally 50 people a week that ask this same question.
A tiny turbo forcing air through unported heads on a stock cam and intake with no intercooler might make 600 HP at 23 PSI and ~5600 rpm and the block live forever. Take the same bottom end, put on ported LS3 heads, a Holley Hi-Ram, a custom grind turbo cam, A2W Intercooler, methanol, and a large billet 88mm, and the bottom end blows apart at 18 PSI at 6400 RPM.
There are literally 50 people a week that ask this same question.
02-01-2014, 05:29 PM
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The question is " how much boost can a STOCK lq9 handle"... are you gonna tell me that NOONE in the whole entire world has EVER put boost on a STOCK lq9... for some reason I find that hard to believe... assuming that all lq9's are basically the same I.e. crank rods pistons somewhat close compression, that NOONE... ANYWHERE... can give me a ROUGH IDEA of what I can do? Im not asking you for a dyno sheet on the matter.. all I want it " hey man I wouldnt put 1000 psi on that bottom end or I put 8 psi on mine and it stayed together... your over thinking the situation
02-01-2014, 05:45 PM
#6
Wow. You've never attended a physics class have you?
Boost has nothing to do with how much a bottom end can handle. 8 PSI doesn't mean ANYTHING in terms of how much a bottom end can handle. 8 PSI could mean 400 HP or 800 HP. 400 HP would be just fine, 800 HP might not be. If someone came in here and said they put 26 PSI to the stock bottom end, and then you tried it with a PT106, you're going to blow the bottom end to hell.
But sure, go ahead and do whatever you want. 30 PSI is the highest I've seen anyone push a stock bottom end. Have fun.
Boost has nothing to do with how much a bottom end can handle. 8 PSI doesn't mean ANYTHING in terms of how much a bottom end can handle. 8 PSI could mean 400 HP or 800 HP. 400 HP would be just fine, 800 HP might not be. If someone came in here and said they put 26 PSI to the stock bottom end, and then you tried it with a PT106, you're going to blow the bottom end to hell.
But sure, go ahead and do whatever you want. 30 PSI is the highest I've seen anyone push a stock bottom end. Have fun.
02-01-2014, 06:00 PM
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You are aparently to smart for your own good. And obviously im way to dumb to try and explain this to you... if you ask me how much psi can a stock 305 camaro motor handle. I would say I put 13 psi on mine and it stayed together... because stock means stock... it dont mean stock bottom with afr heads and 650 cam and highrise single plane... it means stock... I dont understand why you are having trouble with this... let me re-frase the question for other people as your opinion no longer has any meaning. I have a COMPLETELY STOCK lq9 that I am wanting to add a turbo.. it is COMPLETELY STOCK so there are not special intakes no special cam no special heads. Just the ones that came on it. Has anyone out there ever put forced induction on one of these motors that is COMPLETELY STOCK and if you did how much was it and did it stay together. .. Again I am talking about a COMPLETELY STOCK lq9 and it has a horsepower rating that is exactly the same as it was when it was produced because it is still COMPLETELY STOCK...
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02-01-2014, 06:05 PM
#8
Go to the search page. Type LQ9. Search only forced inductions forum. Read the literally over 1000+ posts on people who have boosted them, and please read them ALL before you ask any more questions.
02-01-2014, 06:06 PM
#9
What he is trying to say is that boost is a measurement of restriction after the fact. Ported heads will flow more air or the same air with less restriction than unported heads. So ported heads will back more power at the same boost level or the same power at a Lower boost level than unported heads. If you're are following, now think about your question. Turbo size, cam, intake, heads, and ic or no ic will all affect boost levels. To answer your question is not possible, but 600 ish hp is safe on a stock short block but plenty of people are going past 1000 hp on them. What ever boost it takes to get you there is irrelevant. Hope that helps.
02-01-2014, 06:14 PM
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Nothing has been done to this motor... so porting or not porting or cam size or anything else is all irrelevant. . I have given you all the information about the cam the intake the heads the pistons the rods the crank and the block... they are completely stock... what I want to know is what amount of boost this combination of parts will handle... if this motor is 350 hp stock and all the parts are stock and you say 600ish hp is safe. Then how many psi will it take to reach the limit... lol everything you guys are saying is true. I realize that if I change a cam or intake that I will need more/less fuel to make it run right.. what you dont get is I have given you all of the variables... its a stock motor it has stock internals...
02-01-2014, 06:14 PM
#11
I just saw your completely stock quote. Do yourself a favor and at least put a turboish cam in it with some valve springs. Remember this if nothing else. Stock valve springs will allow the forced air to push the intake valves open before they are supposed to. This is relevant at any good power level. Imagine how long your engine will last with the valves smacking the pistons while your lifters are bouncing off the cam lobes because there is slack in the valve train. That is worst case. Best case is you will not make power over 4500 rpm and then you are stuck changing the cam and springs after the car is done. Not fun!
02-01-2014, 06:18 PM
#13
Yeah I don't think he's following his own question at all.
He asked "Lets think about that for a minute.
Stock Gen 3 rods tend to bend around 800 flywheel HP. Thats not an exact number, and RPM plays in a factor there. This means that if it takes just 4 PSI to hit 800 HP, then the rods will start to bend at 800 HP. If it takes you 500 PSI to hit 800 HP, the rods are still going to start bending around 800 HP, regardless of whether it was 500 PSI or just 4 PSI. The rods do NOT care about how much boost you are running, they only care about the power/RPM.
If you make 800 HP with nitrous, they will bend. If you make it with boost, they will bend. If you somehow manage to make that much power N/A on stock rods, they will start to bend, even at 0 PSI.
Boost has ZERO relation to power, other than more boost often equals more power. There is no linear relationship between the two.
Now if you want to rephrase your questions to "How much boost are you guys running on stock bottom end", then you will get answered anywhere from 4 PSI up to 30 PSI.
He asked "Lets think about that for a minute.
Stock Gen 3 rods tend to bend around 800 flywheel HP. Thats not an exact number, and RPM plays in a factor there. This means that if it takes just 4 PSI to hit 800 HP, then the rods will start to bend at 800 HP. If it takes you 500 PSI to hit 800 HP, the rods are still going to start bending around 800 HP, regardless of whether it was 500 PSI or just 4 PSI. The rods do NOT care about how much boost you are running, they only care about the power/RPM.
If you make 800 HP with nitrous, they will bend. If you make it with boost, they will bend. If you somehow manage to make that much power N/A on stock rods, they will start to bend, even at 0 PSI.
Boost has ZERO relation to power, other than more boost often equals more power. There is no linear relationship between the two.
Now if you want to rephrase your questions to "How much boost are you guys running on stock bottom end", then you will get answered anywhere from 4 PSI up to 30 PSI.
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ShartyMcQueef (01-29-2022)
02-01-2014, 06:20 PM
#16
You have not given all the variables. What turbo or is it a supercharger? All of this matters. Boost is irrelevant. 67mm turbo might take 28 pounds before you get to 600hp. An 88mm will do 600 hp without breaking a sweat (8-10 psi). This is on the same motor so no you have not given all the variables. I am just trying to help.
02-01-2014, 06:20 PM
#17
A HUGE turbo might make 600 hp at 6 PSI. A small one might take 14 PSI to reach that same 600 HP on that EXACT same engine. Therefore, NO answer can be given to you.
Something tells me it would take roughly your IQ in boost to hit 600 HP. Give that a try.
02-01-2014, 06:22 PM
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I appreciate the fact that you were trying to teach me something about asking dumb questions but you really could have taken your pompass attitude and extensive knowledge to another post.. it was a simple question that needed a simple answer.. to technical man
02-01-2014, 06:28 PM
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Well given the fact that im using a stock motor im probably not going to use a 3000 dollar turbo.. if I put a 90mm on all stock then does that mean the heads are going to flow more just because its a bigger turbo? Or are the heads going to flow the same with a 70mm turbo... if thats the case let me know.. then ill go buy a turbo and ask how much boost I can put on the motor with the specific turbo I have...