Parasitic losses are mostly due to supercharger RPM not the size of the supercharger. If you run a EMS setup, it will have less timing (if tuned right). The stock CT uses stock timing. Now you will be leaner but the EMS will just make your setup safer it will not give you more power. Each psi is only 10-15rwhp. The faster you spin the supercharger the less you will get with every psi. I do believe we (all who have a supercharger) need a bigger TB. 4.6 Mustangs that run the 2.1L use a 75mm TB. Kenne Bell found that size to right for the 400-430rwhp power level. We make close to those stock and a 2.1L at 9psi makes 400-420rwhp - really close to what a NSX makes on a 2.1L at 8-9psi.
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Supercharger: Comptech VS SOS
- Thread starter Jdmdohcpower
- Start date
Parasitic losses are mostly due to supercharger RPM not the size of the supercharger. If you run a EMS setup, it will have less timing (if tuned right). The stock CT uses stock timing. Now you will be leaner but the EMS will just make your setup safer it will not give you more power. Each psi is only 10-15rwhp. The faster you spin the supercharger the less you will get with every psi. I do believe we (all who have a supercharger) need a bigger TB. 4.6 Mustangs that run the 2.1L use a 75mm TB. Kenne Bell found that size to right for the 400-430rwhp power level. We make close to those stock and a 2.1L at 9psi makes 400-420rwhp - really close to what a NSX makes on a 2.1L at 8-9psi.
boost pressure, size, and rpm all make a contribution to parasitic losses. I'm not saying the 2.1 isnt better than the 1.7. Personally, I'd like to know why comptech decided on the 1.6 to begin with. Was it cost? Was it emissions/carb?
As with most things, there is a penalty with going too big.
The right answer would be this. If all you want is 6 to 7 psi because you are concerned about safety or you do not want to add an EMS etc then go with the CT. The reason is the largest CT pulley will give you 9-10 on the 2.1L and Comptech felt this would be too much for a stock NSX (without the ability to really control fuel, timing, etc plus running out of fuel with the stock injectors). You would have to get a custom pulley about an inch larger to slow down the 2.1L to get 6 psi and this would be well outside its efficiency range (by turning too slowly). All superchargers have a psi range where they are the most efficient. I believe the CT is 6-9 and the SOS is 9-12. This is based on the rpm speed at which they turn. If you want to go past 12 psi (efficiently) then you would need to go to a supercharger larger than the 2.1L due to the speed needed and thus increased parasitic losses.
I guess when you look at it that way, then I would agree with you.
Personally, if I wasn't going for a set it and forget it setup like CT, I would go turbo (though i like having cats and most systems done use them).
I have thought about going FIC and an 8lbs pulley on my car, but then I think it is really worth 20rwhp for all the potential headaches.. and the answer is always no.
Yes Dave, same here. I have looked at and thought about FI systems for so long I feel like I have a phd in it now. The basic CT system is modest but totally headache free, and a very good value because installation costs are very little, there is no tuning, and there is just not that many parts that can break. Legal anywhere you go. I too have often looked at the "next step", and although I am very much in favor of the power curve of blowers, they are simply sitting in the wrong place on this car.
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Beyond the basic comptech supercharger the best FI system for this car is the one that gets no attention at all. A well designed and brilliant system it is. A few of you know which I am talking about.
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I'm not sure which you are talking about.
$1500 for a tune seems absurd. Ive had about 20 tunes done in my NSX RS6 and ford gt. never even CLOSE to that amount. Hell that even includes paying TWO tuners at ONCE... doing a remote tune, while also paying the dyno operator his usual hourly...
$1500? lol.. especially for a BLOWER. The turbo tune was much more involved IIRC... and STILL didn't cost neearly that much.
$1500? lol.. especially for a BLOWER. The turbo tune was much more involved IIRC... and STILL didn't cost neearly that much.
I've had 3 tunes done and all were between 500-800. If you get charged 1500 then shame on you.
$1500? Sounds like someone got hit with the "NSX tax". That is, the tax people think they can get away with charging you simply because you own an NSX.
I recently had a camshaft manufacturer quote me $4000 for 4 cam blanks, plus $2500 to grind them to spec.
I recently had a camshaft manufacturer quote me $4000 for 4 cam blanks, plus $2500 to grind them to spec.
Dave Dozier. Almost instant response off the variable vain turbos. Intercooler INSIDE the manifold (no pressure loss on long cooling pipes). Turbos that don't sit on the ground with a risk of damage (like most other systems). No oil lines, no coolant lines to worry about. Complete factory look. Low noise. Highly efficient cooling system (very low AIT's). No need to remove major parts of the car's subframe. 440WHP/510 crank at incredibly low boost pressures. Built-in wastegate. Name a problem with turbo systems on NSX's and he has solved it.
IMO the most well designed FI system ever implemented on a street NSX.
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- Joined
- 8 April 2012
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Can you elaborate on you're statement: "I am very much in favor of the power curve of blowers, they are simply sitting in the wrong place on this car".
let me start with this: these are my opinions, I am making some generlizations, every system is a bit different.
A twin screw supercharger (not a centrifugal one) creates a power band very similar to OEM. The curve on a graph is almost identical, just higher. There is no peaking, power delivery is very smooth. Almost an NA type quality, as if you had a V8. This is the biggest upside of a twin screw supercharger. It's instant power, and it is smooth power delivery. So the car's charachteristics and on-track balance don't change that much, it is a bit less work to control than a turbocharger that will be more peaky. I am speaking generally.
The problem with the twin screw is that it sits directly on top of a hot motor. The more power the motor generates, the more heat it builds. Most Internal combustion engines efficiencies in under 50%, in the high 30 to mid to high 40% range depending on design. So more than 50% of the energy being taken in is leaving mostly as heat. As you go from 300 to 400 HP, or 400 to 500, you start to generate much more heat. That heat then reduces the efficiency further, and at some point your power simply starts to drop. The more power you generate, the lower your efficiency number is. You start to fight yourself. You start to have to generate the eqivalent of 2 HP to get one to the crank, then 2.1, then 2.2, then 2.5, and so on. The rate actually works against you. The hotter the ambient air, and the longer the engine has been running at high RPM's, the more of a problem this is.
These dyno numbers are misleading. On my comptech supercharged car, I have had dyno readings from 318 to 395. On the same motor. I had 5 readings and no two matched. One factor is the dynos themselves being different, another is how long I had driven to get to the dyno and how hot the motor was at the time. The comptech supercharger is pretty modest in its output. As you go to more boost, larger injectors, larger superchargers, more fuel, more air, you produce more and more heat. It is one thing to see 420 HP on the dyno on a cold run, another to have the car consistently produce that in a heat soaked condition. So the next solution is to cool that air going into the motor via an intercooler. The problem with this is that with most SC setups, the intercooler gets sandwiched between the hot blower and the hot engine. All the heat rises off the motor and goes into the intercooler, and at some point, it too starts to become rather ineffective. Of course then your tuning comes into play more, as tuning on a cooler motor and tuning on a heat soaked motor need to be different. It's just more work, and more difficult to get right. I understand some here are saying tuning is not that expensive, but to me proper tuning can take many many many dyno sessions under different conditions. Race teams spend THOUSANDS of hours perfecting their tune. I get that a street car is easier and less critical to get perfect. Those that have really good tuners close to them they trust are lucky.
There are two types of intercoolers I know of currently, the SOS Laminova core one, and one that is made by driving ambition. In what I have seen, the driving ambition unit is more solid. The SOS one uses a very good Laminova core, but there just isn't enough room to get enough cores in there to make it be really effective in a heat soaked motor. Overall however, no matter what you do, this becomes an issue, especially as you start to go to 400, 500, 600 HP. A turbo on the other hand, doesn't need to have its intercooler sit on the hot motor... so it can do a much better job, and tuning is also a simpler matter. There is less variance, less temerature fluctution.
Everyone has personal needs and personal goals, everyone likes one type of response better than another. So none of the FI systems are bad, it is a matter what matters to you. A good thing, there are also many units to choose from.
For me, personally, I have realized that I would not go beyond a CTSC with a blower, I would just go to a turbo. The CTSC has great appeal because as I have said many times, it is a bolt-on. Requires no tuning. You can read even on this thread the experience of a member with bad tuning. It cost him a motor. The Comptech doesn't run perfect. It runs rich... but rich is safe. It comes at the cost of power, but it gives you a margin of safety. Frankly, I would not have an issue buying a used NSX knowing it previously had a CTSC on it, I would be more hesitant buying a used NSX with any sort of previously installed engine management and tuning. I know what the FMU did in the CTSC, I don't know what the tuner did with his laptop. This is not to say you cannot get a better and safer tune than what a CTSC does even, but I just don't want to have to explain all of this to the buyer of my car. When you are involved in an engine build or tuning, it is going to scare a lot of people off. For me, I have been happy with the simple nature of my CTSC and satisfied with the power level. More is always good, but the question is.... do I take that next step on a low milage 2005 collector year car. If I did, I would hand my car over to Dave, pay him what it takes, and beg him to do an aerocharger system for me. Or, I might yank off the CTSC, sell it, and go with the new NSX.
Taking that next step beyond the CTSC is kind of a major step.
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Yes, Dave's set up is very nice. Isn't it loosly based on the old cartech kit?
Maybe, I am not sure but certainly Dave has put together something really nice. Not cheap, but nice. It's very stock. So is the SOS twin turbo but you have to remove part of the nsx skeleton for that one. Plus Dave's intercooler is just ingenious. It's just really well done. I am really looking forward to see what he does with the infinity EMS. He car is also a 2004 so it's nice for me to see this being done on a late model OBDII car.
cptnsx - I respect your opinion so help me think thru this one. I've always considered upgrading to the 2.3L blower. I have not yet done so because since i've somewhat retired my NSX from the track I don't really encounter heatsoak problems on the street therefore the need to upgrade has diminished. I'm also very happy with the 1.7L @ 7lbs (though as you know I *might* be higher than that based on the RS*R dyno day) from a power output perspective as well as from a boost/engine response perspective. Would like more power? Maybe, but not at the expense of all that additional stress on my engine and drivetrain components. The incremental gain of ~50wHP is not worth the exponential increased risk in parts breaking - at least in my book.
Having said that, let's talk about the 1.6/1.7 vs. the 2.1/2.3. Let's throw out fueling issues from this equation for now by assuming whatever blower I get it will be accompanied by the proper injectors, fuel pump, FPR, and EMS, etc (i.e. not the limited stock injectors, FMU, RRFPR, etc). Let's also throw out meth and an aftercooler out of the equation (due to its added complexity and cost)... Though let's keep all else stock on the block and the drivetrain.
Question: A 2.3L or 2.1L needs to spin at a slower (cooler but under it's optimal range) rpm to push the same cfm of air at 7lbs where as a 1.7L at 7lbs can spin within it's "optimal" range but hotter; is this correct? So the question is... at what boost levels do you want to run which determines the appropriate blower size? What am I oversimplifying here? In other words, if I want to remain at 350-380 max wHP and 7lbs of boost gets me there, then a properly sized blower would be the 1.7L?
On a side note, DDozier is pushing 400wHP at only 6lbs on his aeromotive variable vane turbo setup. I'm trying to use boost pressure as a constant for discussion's sake but I know it's not always an apples to apples comparison when you take into account heat and cfm.
The only reason I had initially considered a 2.3L is for lower IATs w/o the use of meth or an aftercooler. However, I really do not want to push any more than 380wHP. I also do not want to underdrive the blower so much that it will be out of it's efficiency range. When you say above that the efficiency range of a 2.1L is 9-12lbs that makes me wonder what the efficiency range of a 2.3L would be? This is why I do not want to go with a 2.1L+ because guys like me would consider this overdriving the stock motor past it's safety thresholds. 7lbs for a 1.7L seems like the sweet spot for this particular blower. I just wish the damn thing would run cooler therefore I'm still considering the meth option even if it means only a 30-40F benefit in IAT cooling.
What are your thoughts?
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Ryu I think what you are trying to ask is which blower would be the more properly sized blower for this motor at around 380 HP with the fueling requirements met exactly the same manner. Right? If on an EMS then they would both be on an EMS, and if on an FMU and stock injectors then they would BOTH be on that. Because if that is not what you are asking, you are throwing in another huge variable of fueling, timing, tuning, and management into the equation.
I believe the answer to your question is the 1.7L, but the difference will most likely be very small if it matters at all. I'll let cptnsx answer this.
I believe the answer to your question is the 1.7L, but the difference will most likely be very small if it matters at all. I'll let cptnsx answer this.
I didn't want to complicate matters so my initial question basically throws out the comptech fueling solution. Sorry if I didn't articulate that properly.
I think we all can agree the Comptech fueling solution is adequate, it works, but it certainly is far from optimal and still a bit crude given today's available options. Though, for a purely plug n' play solution.. it can't be beat.
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Also, I think the difference is not small but indeed very big.
Let's assume cptnsx's ranges of blower optimal boost pressures is correct. So on the NSX the 1.7L is most optimal at 6-9lbs and the 2.1L is 9-12lbs. That's basically the difference between low boost and high boost in a typical CTSC setup and the difference in the load of the engine is exponentially increased even with the proper matching injectors, etc... (just think clutches, axles, and all the other stuff that gets more complicated with simply a 3lb boost increase)
I think I look at this differently than most folks. I see a lot more reliability issues with a 9+lb setup on the NSX. I can't remember the last time someone blew their motor from a "low" boost 6-7lbs setup. I value reliability a lot more than power... so i'm probably the minority here.
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- Joined
- 8 April 2012
- Messages
- 675
thanks for elaborating TURBO2GO, I actually agree with you're opinion as I think the power level, CARB approval and simple plug and play makes it a win,win for my needs; On the other hand I am looking for available options to make it more efficient by tackling IAT temp, also somewhere in my mind I remember reading about someone running somewhat on the lean side but I cant remember the details (to much reading late at night:smile
so far I am planing to add the Prospeed intake gasket and will see how AFR look when on the dyno and take it from there.
Has any one read or heard of one having some AFR issues?
so far I am planing to add the Prospeed intake gasket and will see how AFR look when on the dyno and take it from there.Has any one read or heard of one having some AFR issues?
I have been following this thread and want to add a clarification, perhaps a data point/correction.
My standard Autorotor application (installed and tuned by Shad) at its peak hits/reads 8 psi on a SPA digital gauge though when we dynoed/tuned it the manifold pressure was at about 7.1. The actual gain was 107.7 rwhp and 47.8 lbft.
I am with TURBO2GO and RYU regarding staying with this setup (running the piggyback fuel by CTSC) for its simplicity, reliability and above all being CARB legal.
My standard Autorotor application (installed and tuned by Shad) at its peak hits/reads 8 psi on a SPA digital gauge though when we dynoed/tuned it the manifold pressure was at about 7.1. The actual gain was 107.7 rwhp and 47.8 lbft.
I am with TURBO2GO and RYU regarding staying with this setup (running the piggyback fuel by CTSC) for its simplicity, reliability and above all being CARB legal.
I agree with Turbo on this. If you just want 350-380rwhp then the 1.7L is the way to go esp if you already have a CTSC. Let say you were starting fresh, then it would be a toss up between the 1.7 and the 2.1. If just wanted plug and play then the 1.7 with the CTSC. If you wanted a system with more flexibility and control the the 2.1L with the SOS. The SOS would allow with the intercooler the ability to take advantage of the lower iat to increase the boost to 9 psi. A intercooler on the CTSC would render the plug and play component of that one moot. You would have to go to some kind of ems or piggyback (which are not great for the NSX). The CTSC counts on high iat to "pull" timing for you.
The 2.3L would require a 4.8 to 5" pulley to run around 7 psi. That is very big. I don't know of anyone running pullies that size on superchargers. Another option would be water injection instead of meth. Without an ems, meth injection would affect your a/f ratio more than just using water to cool the iat. This while not optimal would give you 20-25 degrees of cooling without making you excessively rich.
Personally 9 psi is not too much for an NSX if you use the 3.2L (its stronger, has multi-layer head gaskets already, FRM lining, revised pcv head design, etc) have access to higher octane, and can get a great tune with a full ems. If you have the 3.0 esp one with high miles I would not go past the low boost CTSC. A very small water injection shot would make this safer if set up right.
If 9psi is your goal.....why bother at all with a supercharger? The beauty of what the entire concept of the CT is goes right out the window when you change the pulley, including the CARB certificate since you then have to use an AEM.
My thoughts exactly on this one. Thanks for confirming. I have 1991 3.0L with a lot of happy miles. I was shocked I was still able to pull ~350wHP on a conservative dyno on the 1.7L Autorotor to be honest. Most are doing only 320wHP on the same stock motor. The current plan is to try out either a 50/50 meth/water or a perhaps a 20/80 meth/water mix using an FIC or EMS to adjust injector duty cycles but be very conservative on timing so essentially i'm not tuning for meth - it's just a nice safety feature while keeping everything at the low boost 7lbs. I'll give it a shot and report back in a build thread I'll put together eventually!
Sorry for the off-topic. I agree with you, Turbo, and Hrant. Thanks for the knowledge sharing everyone.
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I'm right around 400whp with my whipple 1.6 running 8lbs. I ran a member with the SOS SC with an Ems and he had the low boost kit 6lbs. I pulled him in every gear. Yes I'm running 2lbs more but like I mentioned previously the difference at these boost levels is about 20whp. He told me he made 387whp I made 365whp at the same boost level. Where the SOS system shines and makes great power is when you add the intercooler but that is very expensive. Once you drop the IATThe system makes great power
SOS supercharger + tune + brace and cover + intercooler = $15,600 with an $800 tune. Add installation and you are into it for at least $17,500. Add headers and you are now at around $20,000 installed.
You can get QUITE a turbo system installed for that kind of $$. Which is why I'm saying trying to get high HP blown isn't quite worth it. And neither is 50 state legal like the CT supercharger ($10,500 installed by an Acura dealer in Boston). You have your CARB certificate and you go to any inspection station, they plug into your OBDII like normal and eveything is smooth sailing. If I'm going to deal with emissions bullshit and having to talk to the cousin of a friend whose buddy can get me a sticker, it better be for some serious HP.
You can get QUITE a turbo system installed for that kind of $$. Which is why I'm saying trying to get high HP blown isn't quite worth it. And neither is 50 state legal like the CT supercharger ($10,500 installed by an Acura dealer in Boston). You have your CARB certificate and you go to any inspection station, they plug into your OBDII like normal and eveything is smooth sailing. If I'm going to deal with emissions bullshit and having to talk to the cousin of a friend whose buddy can get me a sticker, it better be for some serious HP.
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