I was reading your post and If you could just explain a little clearer a few of your points. I got lost right after "Sorry", if you could go into a little more detail on the section that follows that I would appreciate it.
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How to Make 396 Hp at the wheels
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hejo, you took the words right out of my mouth...
this is turning into a regular geek-fest in here (said in great admiration of hejo and folks who actually get into the details to that level :>) me, i think in terms of "turn the key, press the big pedal on the right and it'll go fast".
be well, all.
hal
this is turning into a regular geek-fest in here (said in great admiration of hejo and folks who actually get into the details to that level :>) me, i think in terms of "turn the key, press the big pedal on the right and it'll go fast".
be well, all.
hal
Another set of calculators. Check out the injector one as it tells you a lot of info about the impelementation.
http://www.bgsoflex.com/auto.html
http://www.bgsoflex.com/auto.html
Hejo,
Nice job, but am I mistaken to say that it leaves the stock injectors falling well short at 96 psi and 80% duty cycle unless they are in fact way under rated?
The rated stock 270 hp is at the crank, while the dyno measured 380 is at the wheels. Perhaps more significantly, the power at the wheels is after parasitic losses of the SC. I'm guessing them to be at least 40hp at 8k, and probably a good bit more, unless this type of blower is phenomenally efficient. (I've been asking this question for a while, but no answer yet. One of these days I'll go read the propaganda on the manufacturer's web sit.)
So, given my assumptions, the engine must produce the equivalent of ~460 hp at the crank to get 380 to the rear wheels, which means that the injectors need to perform significantly better than rated. I suspect that it's a combination of above rated flow and something over 80% duty cycle.
If anyone has a good stock injector, mail it to me and I'll have it tested.
BTW, this still leaves me wondering about the stress on a stock block. Is there a reliable source of information about it's limits?
One more question: Do we know the exact boost used for the dyno test?
Nice job, but am I mistaken to say that it leaves the stock injectors falling well short at 96 psi and 80% duty cycle unless they are in fact way under rated?
The rated stock 270 hp is at the crank, while the dyno measured 380 is at the wheels. Perhaps more significantly, the power at the wheels is after parasitic losses of the SC. I'm guessing them to be at least 40hp at 8k, and probably a good bit more, unless this type of blower is phenomenally efficient. (I've been asking this question for a while, but no answer yet. One of these days I'll go read the propaganda on the manufacturer's web sit.)
So, given my assumptions, the engine must produce the equivalent of ~460 hp at the crank to get 380 to the rear wheels, which means that the injectors need to perform significantly better than rated. I suspect that it's a combination of above rated flow and something over 80% duty cycle.
If anyone has a good stock injector, mail it to me and I'll have it tested.
BTW, this still leaves me wondering about the stress on a stock block. Is there a reliable source of information about it's limits?
One more question: Do we know the exact boost used for the dyno test?
By the way, to "Primetime-Vtec"
I found my original Monrone Sticker from my 1991 NSX. It reads "V-TEC"
With a HYPHEN in it.
So HAH.
I found my original Monrone Sticker from my 1991 NSX. It reads "V-TEC"
With a HYPHEN in it.
So HAH.
sjs - I think 460hp might a bit high as that would mean you'd have 18% loss from the crank. Only 3% difference in losses makes the difference of 20hp@crank. Also using 460hp the injectors would have to run at 98% duty. I agree with you, I think it's a combination of the two.
More thoughts about this subject if your interested...
This area of engineering gets to pretty complicated because it involves volumetric efficiency, pressures, temperatures, RPM, bore and stroke, etc. Normally engine design is a taught at the senior year of a Bachelors program and more often offered as graduate level work.
There are several things that are not taken into my calculations. When you take an engine designed to be NA and supercharge it, the actual increase in the amount of fuel flow required is less than compared to increase air flow required.
When you super charge a NA engine the efficiency get better and this ends up changing the fuel requirements.
Fundamentally I don't have the bandwidth or time to spend calculating the impact of supercharging the NSX engine but I feel comfortable after running some basic numbers that it is achievable which Mark's dyno results seem to validate.
So I think this answers "4g62bt2c30a" statement "prove me wrong". Sorry you are wrong, the results and math prove it.
But this doesn't answer the question about how under rated are the stock injectors, "are they being pushed to much". Another thing to keep in mind is the push over the 80% mark only occurs for the last 20+ hp past the torque peak. As Mark said
So may the BB is not the best set up for drag racing but for road course I suspect it's going to be fine. Testing will get Mark the reliability data he needs for warranty.
My qut is telling me the NSX is an incredibly efficient engine which has a big impact on the calculations. But I can't prove it through calculations because I don't have access to the data nor the time to do it. I have the NSX engine at 31% but I think it's higher given the level of engineering that was put into the design.
I also want to add a couple of my thoughts about how this and the BaschBoost update, from MB thread.
sjs I appreciate your questioning and probing of trying to understand how something is being accomplished. Your post have been mature and I've enjoyed the exchange of questions and information.
Corey "4g62bt2c30a" I hope you've learned why it's important to understand the formula's before relying on them so heavily.
prime_VTEC I didn't want to mention it before BUT I studied VTEC like concepts in college 10 years before they were released into the market. Additionally we studied continuously variable transmissions (a.k.a. CVT) will make a bigger impact in my view.
Last I'm in no way involved with the work being done by M&M on BB. My interest was in understanding what I thought was a valid question being ask. I saw data as proof something could be done and wanted to figure it out for myself how it could be so given some interesting questions.
Updated calcs.
If 3.0L NSX engine is SuperCharged
Given Injector size 240 cc
Tested Flow pressure 43.5 psi
Operating pressure 96 psi
Effective Flow rate 356.5350493 cc
Max Flow rate 33.95571898 lb/hr
Desired Duty Cycle 98.5% %
Designed Flow rate/injector 33.4463832 lb/hr
# of Injectors 6
Mf = 200.6782992 lbs/hr
And from above since this should not change dramatically
sfc= 0.435652078 lbm/hp-hr
n= 31% percent
then Power= 460.6389123 hp
Hejo--VERY COOL!!! I really appreciate all the work you are putting into this thread as it is quite educational for us!
I have a question about the 96psi number. I know Mark stated that the (beta) system was running at a max of 96psi, I assume this is at the rail and not in the manifold so if the manifold were at 5psi then would the real fuel pressure in the manifold be 91psi? Another question is (and I guess this is for Mark B) if one looks at the ’92 Service Manual pg. 3-5 it states that the relief valve (see pg. 11-98) on the fuel pump opens anywhere from 71-92psi. If this is true, then how do we come up with 96psi at the rail without a second-stage pump?
On another somewhat related note, I just recently came across a relatively inexpensive OEM intake that has been ExtrudeHoned and I will be installing it sometime this winter. While my intake is apart, I’d like to have my fuel injectors blueprinted, does anyone know of a good company to do this and possibly flow test the injectors at different PSI levels?
DanO
I have a question about the 96psi number. I know Mark stated that the (beta) system was running at a max of 96psi, I assume this is at the rail and not in the manifold so if the manifold were at 5psi then would the real fuel pressure in the manifold be 91psi? Another question is (and I guess this is for Mark B) if one looks at the ’92 Service Manual pg. 3-5 it states that the relief valve (see pg. 11-98) on the fuel pump opens anywhere from 71-92psi. If this is true, then how do we come up with 96psi at the rail without a second-stage pump?
On another somewhat related note, I just recently came across a relatively inexpensive OEM intake that has been ExtrudeHoned and I will be installing it sometime this winter. While my intake is apart, I’d like to have my fuel injectors blueprinted, does anyone know of a good company to do this and possibly flow test the injectors at different PSI levels?
DanO
I'd like to see a NA motor put down 350-380rwhp. Anyone out there know of any?
hejo,
I’m not suggesting 18% losses, more like 11-12% which seems to be the general consensus value for the NSX. However, there are still the supercharger mechanical losses to consider. Even though you don’t see those ponies on the dyno, the engine must create them to twist the screw. But that’s as far as I get. I don’t know for sure that you treat them the same in such calculations as the HP that actually gets to the flywheel, but I can’t see why not. That’s why I said “, the engine must produce the equivalent of ~460 hp at the crank”, part of which never gets past the front of the crank where it is used to drive the SC. I’ve pulled 40hp out of the air for that figure, but I doubt that’s too high.
Edit - Actually, I guess if you use 11% loss to the crank, then you need over 425 at the flywheel. So my 460 figure assumes less than 35 to drive the SC.
[This message has been edited by sjs (edited 03 December 2001).]
Not from a 3.0 or 3.2 and be even remotely drivable on the street and reliable. (Assuming you don't mean NOS.)
for the amount of money for a N/A motor to put that kind of horsepower to the wheel you can have two superchargers on your nsx ;-)
contact John Vasos at Acura of Brookfield. They have a place they use for their track-modded cars.
The Phase NS (Street car) runs something like 340hp or so Normally Aspirated.
YES you can N/A Tune an NSx to over 380hp..
but its my understanding that it loses alot of its driveability due to the Power Band shifting to the extreme high end.
The Revolution NSX runs also runs something like 380hp..so its definitely possible..just not cost effective.
YES you can N/A Tune an NSx to over 380hp..
but its my understanding that it loses alot of its driveability due to the Power Band shifting to the extreme high end.
The Revolution NSX runs also runs something like 380hp..so its definitely possible..just not cost effective.
As I remember Paxton says that it takes ~ 10HP to turn the NOVI1000 SC at MAX output.
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need more info? please private me @
[email protected]
Mark Johnson, CEO of Custodial Services @ Dali Racing, a Not For Profit Company.
WOW!!!! From what little I know that isn't just good, it's fantastic.
I'm told (by a normally reliable source) that the Ford Lightning uses ~85 HP at max RPM. Granted, it uses an Eaton Roots-type blower rather than the Novi and its a bigger engine. But the engine also hit's it's max 360HP at 4700 RPM, not 8k. So, I figured something less than half the loss would be pretty good, but 10HP would be incredible.
The Paxton site was no help. If it's so efficient they should be a lot more vocal. I'll keep looking.
One bit from the site that relates to earlier comments by someone, they use a factor of about 1.22 (122%) in estimating the fuel required by an SC engine vs an NA engine of the same HP. In other words, they need to run richer. I think that's generally known, but it's interesting to see them put a value on it.
One bit from the site that relates to earlier comments by someone, they use a factor of about 1.22 (122%) in estimating the fuel required by an SC engine vs an NA engine of the same HP. In other words, they need to run richer. I think that's generally known, but it's interesting to see them put a value on it.
I had used 1.2 in my original calcs. I don't think the .02 will make that big a diff.
Anybody got answers to DanO's post?
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Hejo,
Quote:
"When you super charge a NA engine the efficiency get better and this ends up changing the fuel requirements."
"My qut is telling me the NSX is an incredibly efficient engine which has a big impact on the calculations. But I can't prove it through calculations because I don't have access to the data nor the time to do it. I have the NSX engine at 31% but I think it's higher given the level of engineering that was put into the design."
I find this is an interesting question and I don't recall hearing the claim before for blown engines.
Please don't take this as a challenge to the statement, but simply a request for directions that might enable me to learn more on the subject. The 31% figure also seems quite high for an Otto cycle engine. Could you point the way to verifying these statements?
anvil
Quote:
"When you super charge a NA engine the efficiency get better and this ends up changing the fuel requirements."
"My qut is telling me the NSX is an incredibly efficient engine which has a big impact on the calculations. But I can't prove it through calculations because I don't have access to the data nor the time to do it. I have the NSX engine at 31% but I think it's higher given the level of engineering that was put into the design."
I find this is an interesting question and I don't recall hearing the claim before for blown engines.
Please don't take this as a challenge to the statement, but simply a request for directions that might enable me to learn more on the subject. The 31% figure also seems quite high for an Otto cycle engine. Could you point the way to verifying these statements?
anvil
Agreed, particularly give the margin of error in the rest of our estimates.
Hey no problem with asking because I was actually rethinking some of this last night. What's bothering me is normally when you design a supercharged engine you have to lower the compression ratio to compensate for the increase net mean effective pressure (bmep) along with increasing the inlet density. When you do this the specific fuel consumption (sfc) increases and imep increases which ends up lowering the efficiency. Which is why the sfc for engines designed to be supercharged are higher than NA engines.
But with the NSX we have an engine that was not designed to be supercharged from the beginning. So what I remember is that when you supercharge an NA engine the power is increased somewhat and some efficiency is gained because of better breathing. Increased air helps with better expansion and lower exhaust temps which effect efficiency. But hey it's been 20 years since I looked at this stuff!
The bottomline is there are so many variables that effect performance and efficiency it's extremely difficult to compute it if not impossible. I'm sure this is why a lot of work done in the labs. Maybe a part time ME like Andy Vecsey can answer. Where are you???
BTW the efficiency is calculated is based purely the hp achieved from Mf (mass of fuel supplied per unit time). If the Mf I calculated from the injectors is off that's going to directly effect the efficiency calculation.
I based the Mf on 6 injectors each with a flow rate of 19.60434349 lb/hr. My # for Mf could and most likely is wrong which I why I ask people who know the real #s to speak up. So the question is what is the "real" flow rate for producing 270 hp on the 3.0L engine. This and what is the real specs on the injectors. Anyway, yes 31% is pretty good!
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Hejo,
Thanks for the reply.
Your interpretation of efficiency seems close to my understanding, although the thermal analysis usually gets into temperatures for the ideal cycle designs. Still, the notion of comparing fuel consumed to power produced is the essence of an efficiency analysis.
The optimum efficiency of any engine, including the NSX, would not be produced at the maximum power (270hp for the 3.0 liter) but at a lower engine speed where air flow is less restricted and combustion is more complete. So your analysis using maximum power and maximum flowrate would appear likely to generate a lesser efficiency than that achievable at the lower operating speeds.
Now at those lower speeds, using the same compression ratio in an NSX, a greater quantity of power should be produced in an SC engine since the increased mass of air and fuel in the cylinder effectively makes the engine a larger displacement device, but only with fuel flow rates and power production figures would we have an answer about its efficiency. It is not clear that there would be an improvement. For one thing the small cylinder cannot expand the heated gas as far as the larger cylinder of a larger, normally aspirated engine.
I've been inclined to think more hp/liter implied more efficiency, but that is probably wishful thinking.
anvil
[This message has been edited by anvil (edited 04 December 2001).]
Thanks for the reply.
Your interpretation of efficiency seems close to my understanding, although the thermal analysis usually gets into temperatures for the ideal cycle designs. Still, the notion of comparing fuel consumed to power produced is the essence of an efficiency analysis.
The optimum efficiency of any engine, including the NSX, would not be produced at the maximum power (270hp for the 3.0 liter) but at a lower engine speed where air flow is less restricted and combustion is more complete. So your analysis using maximum power and maximum flowrate would appear likely to generate a lesser efficiency than that achievable at the lower operating speeds.
Now at those lower speeds, using the same compression ratio in an NSX, a greater quantity of power should be produced in an SC engine since the increased mass of air and fuel in the cylinder effectively makes the engine a larger displacement device, but only with fuel flow rates and power production figures would we have an answer about its efficiency. It is not clear that there would be an improvement. For one thing the small cylinder cannot expand the heated gas as far as the larger cylinder of a larger, normally aspirated engine.
I've been inclined to think more hp/liter implied more efficiency, but that is probably wishful thinking.
anvil
[This message has been edited by anvil (edited 04 December 2001).]
That's it! You absolutely right. That's what was bugging me. So what we have is the efficiency at the max power rating on the NA 3.0L and most likely this is not the optimal point for measuring efficiency. I remember that was a problem we had to solve for in a lab, determining the efficiency of motor and plotting it over RPM.
[This message has been edited by hejo (edited 05 December 2001).]
OK, so where does that leave us? Since we are interested in the worst-case to determine minimum required capacity, what can we assume to be the efficiency at max HP?
Realistically I don't believe the efficiency is going to vary more than maybe 2-3% in the powerband range. A 3% change would probably put the injector at the upper limit of what I calculated. But my numbers are very rough and as such I think best case we can only use them as estimates. So if you take the dyno results using stock injectors and custom fuel management system with the rough calculations hmm okay it's reasonable. Is it completely obvious? Not really.
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