I was just wondering how much 1lb of boost adds in hp figures? Or just a general idea. Thanks
Steven
Steven
how much hp does 1lb of boost add?
- Thread starter 9T5SVT
- Start date
Let's see:
What volume of air is the blower moving?
What is the flow of the intake from the throttle body through to the runners?
What backpressure or lack there of do you have?
Tune?
So many varibles that it's a wild ass guess.
What volume of air is the blower moving?
What is the flow of the intake from the throttle body through to the runners?
What backpressure or lack there of do you have?
Tune?
So many varibles that it's a wild ass guess.
There is no one number as you probably know. But IF you had to put a number to it, most say 1 lb is usually 10 HP. Maybe more from Turbochargers. From that number though it can go up (or even down) depending on alot of varibles. Some varibles are the the motor set-up(heads/cam/ and compression) the tune, weather condition, and what type of FI your using and what the size is on the inducer and exducer if we were talking about turbos.
I would say 15-18hp per pound. That's my guess and I stickin with it.
PoisonSnake
Banned
So if it's good to have backpressure does that mean a catted X would be better then an off road H? since cats gives backpressure.
six bolt said:
Well, duhhhh, . . . . We all know that boost is a measure of pressure. But, as you increase boost, you obviously increase the airflow into the motor which also increases your horsepower. He is just trying to get a general idea.
Be nice :beer:
My car went from 248.3 to 430-440 rwhp (took off pulleys and dyno'd) running 10lb of boost on a procharger p1sc w/ 3 core intercooler.
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I'm losing faith in the newbies being intelligent. If you increase boost something strange normally happens as a result, can you guess?six bolt said:
Thanks for the replies. Yeah, i'm just trying to get a general idea of the gains of smaller pulleys. I still have the stock eaton, i just put a stock 00L pulley on. I installed it today and if felt like a pretty good increase, although after the car sat for about 3hrs, it acted really weird when i started it. It cut off, then wouldn't start, then all my dash lights came on.., but then it just started running fine. I don't know, guess it didn't recognize the new tune.
Steven
Steven
Usually about 13hp per 1psi according to Kenne Bell.
Does a 120 HP 1.6 L 4-banger produce the same HP increase per psi boost as a 500 HP Viper V10?
Obviously not. Not even close.
Okay, then what relationship DOES apply to both, or more generally to any internal combustion engine, with regard to boost?
:idea:
How about the following?
Since this estimate expresses the HP gain as a percentage of the engine's EXISTING power, it works fairly well for just about any motor.
T-
Obviously not. Not even close.
Okay, then what relationship DOES apply to both, or more generally to any internal combustion engine, with regard to boost?
:idea:
How about the following?
Since this estimate expresses the HP gain as a percentage of the engine's EXISTING power, it works fairly well for just about any motor.
T-
A Robinson.
Banned
Depends on the tune,heads cams compressor size..ect. Charged air temperature and compressor efficiency also play a large role in how much power can be added as boost levels increase. A larger blower/turbo will move more air at a given boost level and almost always make more power. Think of it like being hit at 60 mph by and civic, or being hit by a dump truck at 60 mph.
Example:
On my dsm with a stock head cams and intake manifold with every 1psi of boost added the car made about 12 additional HP. Once we added cams and an intake manifold that number shot close to 25HP per psi. As the compressor got closer to its peak efficiency island charged air temps dropped and we got a lot closer to 25Hp for every 1 psi of boost. Same 12:1-11.8:1 a/f ratio and timing curve under boost. Im using the dsm as an example because the heads on a 4v flow about the same.
Example:
On my dsm with a stock head cams and intake manifold with every 1psi of boost added the car made about 12 additional HP. Once we added cams and an intake manifold that number shot close to 25HP per psi. As the compressor got closer to its peak efficiency island charged air temps dropped and we got a lot closer to 25Hp for every 1 psi of boost. Same 12:1-11.8:1 a/f ratio and timing curve under boost. Im using the dsm as an example because the heads on a 4v flow about the same.
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A Robinson. said:
Are you implying that my simple 7% rule of thumb is invalid? Well, maybe it is. Let's take a look ...
I see that you have cited the difference in your DSM's HP increase per psi boost before and after some significant modifications to the motor itself. Okay, take all the boost away. Don't you think the engine HP without ANY boost at all went up a wee bit? I imagine so. So you'd have a new base HP to calculate from, then, wouldn't you? Yep. That having been said, 7% rule of thumb might be valid both before and AFTER your engine mods.
Also, what does the phrase "rule of thumb" mean to you? My interpretation of that phrase is "rough estimate." It does not mean "exact gain," since, as you said, there are many factors that will skew that estimate one way or another. I've personally seen cars gain as few as 5% or as much as 9% per psi at the same boost levels, but, again, as a "rule of thumb" seven percent is a good average.
Finally, note that this rule of thumb is intended for use ONLY with boost levels up to about 10, maybe 12, psi or less. (At higher boost levels, it's a different ballgame.) If you were pushing significantly more boost with your DSM, which I imagine you were, this particular "rough estimate" most likely wouldn't be applicable.
T-
killspray said:
yea but what your saying is somewhat one in the same. Boost is added air pressure....... which is increased airflow. Boost = increased airflow. Its like your making 3 parts of the equation when there is only two.
DaleM said:
A million things *can* happen. Lean out, detonate, ecu pulls timing and you LOSE power because of increased boost.
My point was you can't simply ask a question with as many variables as "how much horsepower does 1psi of boost add".
p.s. I'm surpised you had faith the newbies had intelligence
A Robinson.
Banned
Taz said:
yes
why would you take boost away from a low compression motor setup specifically for boost?
Not to be rude but you have no clue what you're talking about. every compressor has a boost level where it reaches it peak efficiency. most times its right around 25 psi
As stated in my first post the boost level was consistant.
A Robinson. said:
First, you'd want to know what the motor is good for without boost so you can see how well it responds to the F/I when you apply it. It doesn't freaking matter that you've built a low compression motor with blower cams, etc. It's called a baseline. (BTW, I'm sure that, being the expert you are, you KNOW low comp makes LESS HP per psi boost than high comp!)
Say, that's a really diplomatic manner of expressing yourself that you have there, Sparky. And let's just take a look who's ignorance is running all over this thread! That 25 psi line is the just about most IGNORANT statement I think I've ever heard about boost.
Lemme see ... supppose YOUR blower is most efficient at 25 psi boost on YOUR motor, which has an "X" cid displacement. Now put your blower on a motor that's got 2X displacement. Guess what. At the same RPM, your blower is still flowing the same CFM that it was on your motor, but now it's not producing anywhere NEAR 25 psi, IS IT??? So, is it still at its max efficiency AT THE LOWER BOOST, or do we need to spin it TWICE AS FAST to bring it up to 25 psi so that we can be back "in the zone" again? Moron.
I've got more friggin' compressor maps on my hard drive than you've ever seen! (YOu probably don't even know what a compressor map is.) Not a SINGLE ONE expresses any compressor's efficiency in terms of boost psi. It's ALWAYS in terms of rpm and cfm. And the cfm where you achieve max efficiency is going to result in different boost levels on different sized motors. Gee, ya think maybe that's why they make DIFFERENT SIZED blowers???
So You don't like my 7% rule of thumb, eh? And I obviously don't know what I'm talking about?
But you do ... because you're such an ... expert.
Go tell it to Kenne Bell, since that company is my source for this particular rule of thumb. It comes directly from a KB FAQ page. Hey, but what does KB know about F/I? The company has only been doing just that for decades, but obviously they don't have a clue what they're talking about. Maybe you're the one who needs to get a clue. Personally, I've adopted this little rule of thumb BECAUSE IT WORKS, Numb Nuts!
We're OBVIOUSLY not having the same conversation. You seem to SPEAK English fairly well, but you don't appear to comprehend it very well. I implied that you changed your BASELINE when you worked the motor by swapping the cams etc. I DIDN'T say you changed your boost level.
Let me make it real simple for you:
The 7% rule of thumb applies only up to about 10 psi, maybe 12.
Were YOU MAKING MORE boost than 10 - 12 psi???
Then, the rule of thumb does not apply in your case.
Was that so damned hard?
Tell you what, don't bother answering this post. You've already betrayed your ignorance with that ridiculous 25 psi BS. This dialogue is OVER! I initially tried to be civil to you, 'cause I felt bad for the way everybody dumped on you over in the New Edge Forum. But from now on, stay out of my sights.
T-
A Robinson.
Banned
Taz,
The problem with your web-board found percentage based ideas. Comes from the fact that you have not actually done anything other than quote what you have read on the Internet. I suggest you grasp a better understanding through your (own hands on experience) before you try to help others with questions you clearly cant answer with any hard facts.
Go figure out how load based forced induction works and come back. Reading Kenny Bell's website does not qualify you to spread information to others about potential gains from adding boost to their particular setup. Bottom line is there are to many specific variables to consider in regard to power production with a blower or turbo.
I apologize if my *personl experience. In regard to the said topic is offensive to your Internet found formulas for boosted horse power production methodology.
The problem with your web-board found percentage based ideas. Comes from the fact that you have not actually done anything other than quote what you have read on the Internet. I suggest you grasp a better understanding through your (own hands on experience) before you try to help others with questions you clearly cant answer with any hard facts.
Go figure out how load based forced induction works and come back. Reading Kenny Bell's website does not qualify you to spread information to others about potential gains from adding boost to their particular setup. Bottom line is there are to many specific variables to consider in regard to power production with a blower or turbo.
I apologize if my *personl experience. In regard to the said topic is offensive to your Internet found formulas for boosted horse power production methodology.
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