how much time do you have on it?thought it was a newer build
Destroking - Facts or fiction
- Thread starter Jerryl
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hmm,interesting.the ones i have been in were soft till higher rpm (overcomed by transbrake)but the turbo and cam has alot to do with the setup.
Jerryl
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If I wanted to go fast and have reliability, I would build a high compression off center S2 (4" bore) with 3.4" stroke. That is the best of both worlds IMO.
NY Twin Turbo
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Kinda cool. Because this is exactly my combo.
Jerryl
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Your car is a well-known Rock Star in the buick world.Kinda cool. Because this is exactly my combo.
NY Twin Turbo
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Thank you. But let me correct my last statement a little.
I'm not really sure how "high" my compression is. But I was led to believe it was "higher and still be street boost and street fuel friendly." And this seems to be the case because it's been on the street 12 years solid now. It has been revved pretty high (not by me) with no ill-effects. And after I complained about the shift points, I was told "there is still a lot more in it, so stop complaining."
Iv'e said it before. Ignorance is bliss.
But yes. It's a 4.1 off-center, stock stroke, stage motor.
You argue like a Democrat. If I don't agree with you,your open mind tells you that I'm wrong. If the laws of physics don't agree with your open mind,the laws of physics are wrong. If the smaller engine produces less power than the bigger one below 5,000 rpm,the dyno is closed minded.
Im not a dyno guy .. I like to prove things in the street .. which is exactly why I said .. ITS FASTER IN THE STREET PERIOD !
and not by a bit .. it doesn't even feel like the same car .. I honestly could care less about your theory and law of physics ..
and who gives a shit about if it makes less power at 3000 or 4000 or 5000 rpm ...
You have a lot to learn my friend
Pronto
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Dynos are a great tool but they do not show how a car will perform on the street or the track. I've seen 700hp dyno slip Mustangs run 11s.
NY Twin Turbo
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Question...........
Sparing no expense, If using a 109 block, small displacement-short stroke, what would be the RPM limit?
I believe we have been referring to stage motors through most of this thread. But for many of the readers that may never own a stage motor, what options do they have? And far can they go if they wanted to go in this direction on their next build?
Sparing no expense, If using a 109 block, small displacement-short stroke, what would be the RPM limit?
I believe we have been referring to stage motors through most of this thread. But for many of the readers that may never own a stage motor, what options do they have? And far can they go if they wanted to go in this direction on their next build?
ive spun them to 7200/7500 rpm stock stroke,and had a combo that would spin 6600 to 6800 rpm all day.the destroked stage stuff 8500+,a destroked 109 will be limited to the block itself like all 109s when that power level is reached it will be at a higher rpm.there are ways to make the power sooner but that rpm window opens alot of options with the turbo and converter.
434nova
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A 3.5 stroke on a big block is a short stroke motor. They are big bore short stroke engines with 18 degree heads with over 400 cc intake ports. But I see where you are coming from, I agree with a bigger motor making more power if you can feed it the airflow needed to make power.
its why i asked what turbo was being used
Jerryl
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Disclaimer; Attached are MY quick random thoughts and my synopsis is believed to be +99% accurate. You are welcome to disagree and debate.
HP is a calculated number; (RPM * Torque)/5252=HP
Clearly, as rpm increases, so does HP, assuming torque is constant. If torque is decreased, a HP number can still be achieved with increased RPM. Now, for me and my street car, torque it where it’s at IMO.
Here is a synopsis;
Let’s say you have a de-stroked engine, and the head FLOW is the limitation (Think RPM/stock untouched heads). The performance loss on a de-stroked engine can’t be made up with RPM. The performance can be increased with boost, but like everything else, there is a break-even point. (Not sure but probably in the high 50 PSI range with the right fuel)
If these stock untouched heads are operated by a high rpm cam (I am sure nobody would do that right?
), a short stroke (Less CID) may be a better match because the smaller cylinder will fill better. Maybe not to 6K, but you get the idea. In other words; the smaller CID runs more efficient, with the same sh** heads, and can therefore be run at higher rpm.
We understand that torque is a function of “force x lever”; Shorter stroke, shorter lever. Force is result of the pressure applied to top of the piston. (Lb/in^2 * in^2 = Lb)
Clearly, a 4” bore has higher total force for a given combustion pressure over a 3.8” bore. The 4” bore also appears to have increased mass flow, not because of valve size, but un-shrouding. Obviously, the increased CR for the same chamber is a plus as well. (Look up the thread Boost vs Back pressure)
A linear calculation model for simplistic approach comparison;
3.8” vs 4.0” bore piston area is 45.36 vs 50.27 in^2. At the same stroke length; (50.27 - 45.36 in^2) = 4.91 in^2. This is ~11% increase in torque, or ~12.5% HP increase.
A 3.40 vs 3.55 stroke will result in 4.4% increase in torque, resulting in ~5% HP increase.
So do you increase area (Bore) or lever (stroke)? I think bore wins every time, up to the break-even point.
Obviously, some cars will be quicker with de-stroked engine but the contributing factors are not limited to the CID or RPM. It is entirely possible that the converter now slips less at the increased rpm/lower torque, or the cam and ports are now a better match.
Obviously, it’s complicated, and one size never fits all . . . . .
HP is a calculated number; (RPM * Torque)/5252=HP
Clearly, as rpm increases, so does HP, assuming torque is constant. If torque is decreased, a HP number can still be achieved with increased RPM. Now, for me and my street car, torque it where it’s at IMO.
Here is a synopsis;
Let’s say you have a de-stroked engine, and the head FLOW is the limitation (Think RPM/stock untouched heads). The performance loss on a de-stroked engine can’t be made up with RPM. The performance can be increased with boost, but like everything else, there is a break-even point. (Not sure but probably in the high 50 PSI range with the right fuel)
If these stock untouched heads are operated by a high rpm cam (I am sure nobody would do that right?
), a short stroke (Less CID) may be a better match because the smaller cylinder will fill better. Maybe not to 6K, but you get the idea. In other words; the smaller CID runs more efficient, with the same sh** heads, and can therefore be run at higher rpm.We understand that torque is a function of “force x lever”; Shorter stroke, shorter lever. Force is result of the pressure applied to top of the piston. (Lb/in^2 * in^2 = Lb)
Clearly, a 4” bore has higher total force for a given combustion pressure over a 3.8” bore. The 4” bore also appears to have increased mass flow, not because of valve size, but un-shrouding. Obviously, the increased CR for the same chamber is a plus as well. (Look up the thread Boost vs Back pressure)
A linear calculation model for simplistic approach comparison;
3.8” vs 4.0” bore piston area is 45.36 vs 50.27 in^2. At the same stroke length; (50.27 - 45.36 in^2) = 4.91 in^2. This is ~11% increase in torque, or ~12.5% HP increase.
A 3.40 vs 3.55 stroke will result in 4.4% increase in torque, resulting in ~5% HP increase.
So do you increase area (Bore) or lever (stroke)? I think bore wins every time, up to the break-even point.
Obviously, some cars will be quicker with de-stroked engine but the contributing factors are not limited to the CID or RPM. It is entirely possible that the converter now slips less at the increased rpm/lower torque, or the cam and ports are now a better match.
Obviously, it’s complicated, and one size never fits all . . . . .
That's the problem with this thread .. everyone wants to put restrictions on what can and can't be done and what parts are and aren't touched .. and what has to stay static .. what you MUST learn is to think OUT OF THE BOX and make a SYSTEM work not just a component . That means ALL OF IT. I find it hysterical that the most emotional people on this thread have no real world experience with this setup but yet can concretely ascertain that the concept of destroking being beneficial should be null and void just because ...
I have ALOT of time thinking about what needed to happen here as a WHOLE.. it required a complete RE-DO of general theory I've used before .. I dabbled with this exact approach on another platform in the mid 90's and it didn't work like I thought it would, but with the advancement in all facets of the high-performance world .. especially data acquisition ... things are way way different now.. as are the results.
It's for sure not for everyone.. but I know for myself on my own car .. the results have FAR exceeded my expectations and the best part is that I still have plenty left on the table . Cant fight what works and WHY it works..
Food for thought .. some of the FASTEST REAL street cars in the world AREN'T running 500 CID prostock motors
or 700 CID mountain motors ... actually many are running small blocks .. there are even some running smaller than 3.0 liters
I have ALOT of time thinking about what needed to happen here as a WHOLE.. it required a complete RE-DO of general theory I've used before .. I dabbled with this exact approach on another platform in the mid 90's and it didn't work like I thought it would, but with the advancement in all facets of the high-performance world .. especially data acquisition ... things are way way different now.. as are the results.
It's for sure not for everyone.. but I know for myself on my own car .. the results have FAR exceeded my expectations and the best part is that I still have plenty left on the table . Cant fight what works and WHY it works..
Food for thought .. some of the FASTEST REAL street cars in the world AREN'T running 500 CID prostock motors
or 700 CID mountain motors ... actually many are running small blocks .. there are even some running smaller than 3.0 liters An emotional person has a hard time dealing with facts,then he attacks the character and mental capacity of the person on the other side of the discussion as if that has anything to do with weather or not a statement is true. He laughs and ridicules the other person. The emotional person then accuses the other person of being emotional. You definitely do argue like a Democrat.
Your FACTS .. or REALITY FACTS ...
and it's whether not weather
Your PROSTOCK example is a perfect example of FACTS ... 500 CID and 1500 hp = 3 hp per cid ...wahoooo
then you have guys making 8 hp per cid with FAR LESS motor as in 60 CID ...
So yea It leaves a lot to be asked .. remember we aren't limited to class rules here .. anything goes which is why
de-stroking works.
I guess the only intent here is that you want to argue so I'm done here... ramble on with your theory of bullshit
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agreed but that is all about power management.it seems everything makes power now, the real success on the street is in power management.Food for thought .. some of the FASTEST REAL street cars in the world AREN'T running 500 CID prostock motors
