Puzzled by the whp gain after ITB

$5,000 for sound? Should have spent $20 on whistle tips.

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On a more serious note, yeah if your final numbers is similar to what Dan's is making, then you should be where your suppose to be. Don't think of it as total whp gain, but rather the final hp. Also I wouldn't spend money to swap out that exhaust to gain just a few more hp's. Your looking into $1000 if you sell your current exhaust to get single digit gains. Not worth it IMO.
 
OP, 25 is really good and I would not expect more. I am sorry, I just don't buy the 40 HP gain, not saying anyone is being deceitful just saying it was not a scientific test under controlled conditions and that it is not realistic. You can't defy the laws of physics.

ITB's are a novelty item. They look cool and sound cool, but they are not a serious HP mod. It's like going BACKWARDS in terms of technology.

You have something that is really cool now. It's very rare, looks good, and sounds awesome. You paid a pretty penny for it, but that is what love costs. LOL... I'd be happy and not worry about what dan got. I would bet anything that under super controlled conditions your gains are roughly the same. I still advise you to try another exhaust system (if you have access to one without buying just to see the difference or just undo it from the cat back and see) and enjoy the sound of the intake instead.
 
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OP, 25 is really good and I would not expect more. I am sorry, I just don't buy the 40 HP gain, not saying anyone is being deceitful just saying it was not a scientific test under controlled conditions and that it is not realistic. You can't defy the laws of physics.

ITB's are a novelty item. They look cool and sound cool, but they are not a serious HP mod. It's like going BACKWARDS in terms of technology.

You have something that is really cool now. It's very rare, looks good, and sounds awesome. You paid a pretty penny for it, but that is what love costs. LOL... I'd be happy and not worry about what dan got. I would bet anything that under super controlled conditions your gains are roughly the same. I still advise you to try another exhaust system (if you have access to one without buying just to see the difference or just undo it from the cat back and see) and enjoy the sound of the intake instead.

25whp is really good for just an intake. :wink: with how cool it looks and sounds, the power gain is just icing on the cake. :biggrin:

was your car tuned before? the dyno on their site didn't have a chip or any tuning. don't you gain like 15whp with an ECU tune? there's your 40whp right there. the dyno says 40whp with ITB's and AEM EMS.
 
For those naysayers about the gain I made on my ITBs setup... I have no reason or benefit to prove to you that it is what it is.
It was right there on the dyno, the tuner came from another state using another's shop dyno tuning back to back.
I expected 20 WHP gain but got 40 so it is what it is. I can't change the number and what my car ran at the 1/4 mile track.
274 WHP with a 2720 lbs. car= max mph
Before the ITBs purchase, I wasn't looking for huge HP gain... I was being realistic. Chris @ SOS even discouraged me to purchase the system for my stock engine set up. But I went anyway!
So at the end, we got 40 WHP gain... I couldn't be more happy.
The main reason I flew Tony from UMS tuning in because I want to get it done right. Very important is what type of dyno to use for the tune.
Dynapack lets you tune in increment with constant load. That was the first question Chris @ SOS asked when I told him about flying Tony up here for the tune. Everyone can "claim" that they can tune an ITBs set up... but when things don't go right then they start pointing fingers.

TUNING TUNING TUNING with right equipments!!!!!!

It is really sad to see people hating on others for whatever reasons.
It sounds like I don't know my own built and "the expert" knows everything about my built.
Or they just want to accumulate posts to look cool with new members! IDK, just a wild guess.
 
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To OP,

No disrespect to Dan's car at all.. he's got a sweet build, but it is only one build. I believe SoS is quoting Dan's numbers on their site too, though I could be wrong in that also. My point is... it's tough to draw overarching conclusions on just one sample size. FWIW, 40hp seems on the high side for my small brain to comprehend.. so much so it really had me questioning the efficiency of the stock intake system. If anything your 20hp put me back to earth again. 20hp is still a nice gain and for some people the sound and throttle response you now have is priceless.

If I were you, i'd contact Dan's tuner and compensate him for a little bit of consulting time. Perhaps Dan's car has something else or a combination of other things. I'm not questioning his 40hp, I think it's great actually, but all i'm saying is it's just one sample size.
 
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It is really sad to see people hating on others for whatever reasons.
It sounds like I don't know my own built and "the expert" knows everything about my built.
Or they just want to accumulate posts to look cool with new members! IDK, just a wild guess.

No one is "hating" man, just saying your results are unusual and often other things are involved. No need to get upset over anything, no one has been disrespectful to you.
 
I've got numerous inquiries from members wanting to get ITBs. I gave them the same advice, go to the right source and use the right equipments and proven tuner for ease of mind.
It is not easy to not get upset when my honesty taken for granted. But at the end of the day no harms done no hard feelings .;-)
 
I've got numerous inquiries from members wanting to get ITBs. I gave them the same advice, go to the right source and use the right equipments and proven tuner for ease of mind.
It is not easy to not get upset when my honesty taken for granted. But at the end of the day no harms done no hard feelings .;-)

No hate NA1/2-R GT, your car is badass.
 
Please remember that modifications to either the intake or exhaust system are interdependent. The best analogy is of a river with a set of dams or restrictions. When one dam is removed, but others are in place, the net flow will still be affected. Particular components that are more restrictive than another vehicle that are still in place will have an effect on the net flow through the engine.

Our 3.5L high compressions gain 20-25 hp as there are other restrictions in the system in place that are otherwise having an effect on flow.

A 20 hp gain on a 3.0L engine with intake modification alone is pretty impressive.

The exhaust is definitely something to consider. The Pride/GT-One/FN-09 exhaust has a very long run with multiple bends which will reduce exhaust velocity and flow.

-- Chris
 
To those who don't "get" the claims of 40 HP gains...

First of all those gains were achieved with a stand-alone ECU in place of the factory ECU. Factory tune is pretty conservative on the NSX, at least for Honda. I would expect 10 - 15 HP just by switching to an AEM ECU and having it tuned by someone who really knows his stuff and has lots of NSX experience.

Second, ITB systems like the one from SOS can potentially swallow more air faster at WOT than any OEM or aftermarket tube-type intake, even if either is tested without a filter. Flow isn't just about what the air has to pass through. It's fluid dynamics and everything from the intake runner and plenum configuration to the shape of all the tubes through which air must pass to get there can affect that flow rate.

You guys know that. Its why an AEM cold air intake will outperform a short ram intake on any civic even when underhood temps are not an issue. Geometry is important.

The most important design element in the SOS ITB system is probably the shape, diameter, and length of the intake horns. Then there's the absense of the kind of sharp bend air has to travel between the oem throttle body and the intake plenum.

40HP gains may be close to the limit given an ideal exhaust system and perfect tuning but obviously it's possible.

As to dyno results being variable, unless the tech plays with the correction settings or the weather changes a lot between pulls, comparing two runs on the same dyno provides absolutely valid results, plus or minus a couple horses.

Besides ITBs sound cool. :cool:
 
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FD3SNSX, when comparing whp between your car and someone elses, in addition to looking at the exhaust setup you also need to look at sources of parisitic losses...everything from flywheel weight to wheel/tire size and weight to gearing to oil type and viscosity.

Which raises one interesting question. Was your dyno pull done in the same gear as Dan's? Not every shop dyno's in the same gear. And that can make a big difference in the numbers.
 
290+ hp at the rear wheels is nothing to sneeze at. I see you have CT headers. What kind does Dan have? Seems like you don't really make any more hp up until vtec kicks in.

Yeah, wish I was making 290 rwhp. But gains in that dyno sheet get really sweet ramp up a tick past 4500 RPM, or 500 RPM below VTEC.
 
I've got numerous inquiries from members wanting to get ITBs. I gave them the same advice, go to the right source and use the right equipments and proven tuner for ease of mind.
It is not easy to not get upset when my honesty taken for granted. But at the end of the day no harms done no hard feelings .;-)

Dan,

I am really sorry if you got offended in any way. I just want you to know that I was not questioning your numbers/setup. If anything, I was questioning if there was something wrong/missing from my end. You already gave me many advises on the ITB setup and I really appreciate everything you have done for me.

I did not fly Tony from UMS to get my car tuned because 1- My tuner Ray Wilson from PFSupercars is one of the best tuner in the east coast. He has over 15 years of building/tuning cars using almost every EMS available 2 - Id rather have my tuner tune my car even if takes alittle more time because he is closed to me. I can't fly Tony over everytime I need to get my car re-tuned.
 
Dan, I don't think people are doubting or hating on your car. I think this is more just collective forum head scratching. I for one believe both the 20 and 40 whp numbers. Tuning and setup can do a lot. Tons of variables.
 
I expected 20 WHP gain but got 40 ...

The best analogy is of a river with a set of dams or restrictions. When one dam is removed, but others are in place, the net flow will still be affected. ... Our 3.5L high compressions gain 20-25 hp as there are other restrictions in the system in place that are otherwise having an effect on flow.

Could you get rid of whatever restrictions your 3.5L engines have so that they gain 40 rwhp like NA1/2-R GT’s did? What restrictions do the 3.5L engines still have? Is it the mufflers?
 
I'm guessing valvetrain, unless the exhaust is a restrictive design. Was SOS's 3.5L high HP engine dyno runs made without cats? What headers/muffler?

I've never played with ITB's, but the correct intake resonance tuning can alone lead to increased power at targeted engine speeds. I guess I could believe 40HP over a limited RPM range sounds plausible in theory. Similar theories on exhaust collector design/location, and x-pipe merge location can lead to marked power gains as well.

Dave
 
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Max HP is an over-rated goal. What counts is torque spread and HP gain through the revs. Having said that, I notice Dan's low down gains are substantial, whereas yours are next to zero until around 5,400 rpm. And what's with that huge negative torque spike at 5,200 ? Nothing like that on Dan's charts! You're on right path to question the tuning, just focus on torque spread & consistency rather than maxima.

To those commenting that ITB's "only free up air the flow" you're forgetting the the tuned length effect that only comes from a designed trumpet.
 
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I'm guessing valvetrain, unless the exhaust is a restrictive design.

I don’t think it’s the valvetrain. NA1/2-R GT has stock camshafts, stock cylinder heads, and stock valves. The SoS 3.5s have high-lift camshafts, ported and polished cylinder heads, and larger valves. If something is allowing NA1/2-R GT’s engine to breathe easier than the SoS 3.5s and therefore gain more horsepower from the ITBs, I’d guess it’s something else.

Looking at the dyno charts FD3SNSX and NA1/2-R GT posted, it’s not only interesting how much the peak power changed but also where the power changed. NA1/2-R GT got significantly more power at every rpm tested, peaking at a gain of 65 hp at 5400 rpm. Max power was produced at 8000 rpm in both the before and after runs and the gain was 41 hp up there. In FD3SNSX’s NSX, the gains only started coming at 4500 rpm and peak power shifted from 273 hp at 7400 rpm to 293 hp at 8000 rpm. That's still a great gain in top-end power.

ITBs_and_engine_power.jpg


Looking at the percentage change in torque, NA1/2-R GT got a 40% increase in torque at 5400 rpm while FD3SNSX only got 8% at that engine speed.

ITBs_and_torque.jpg


In any case, I hope more before/after dyno tests are carried out. If ITBs get you more power at every rpm, the Formula 1 World Championship-winning engineers who designed the NSX's Variable Volume Intake System did something very wrong!
 
If ITBs get you more power at every rpm, the Formula 1 World Championship-winning engineers who designed the NSX's Variable Volume Intake System did something very wrong!

IMO the VVIS doesn't deserve this much praise. Sure it changes intake volume for a small gain but it's at the cost of a very convoluted / disruptive intake airflow path, especially when compared with any ITB setup. I have a healthy respect for the Honda engineers, but IMO they were tasked to optimize the NSX as an road-driveable GT, not a racer / F1.
 
IMO the VVIS doesn't deserve this much praise. Sure it changes intake volume for a small gain but it's at the cost of a very convoluted / disruptive intake airflow path, especially when compared with any ITB setup.

The VVIS system doesn’t cause a convoluted intake path. The intake air has a pretty much straight shot across from the airbox into the upper chamber of the intake manifold. From there, the air flows up into the intake runners and on into the engine. Above 4800 rpm, holes in the floor of the upper manifold chamber open up, changing the effective volume and therefore the resonant frequencies but the air still flows straight into the upper chamber and from there up into the intake runners. The holes in the floor surely disrupt the air flowing across them somewhat when they are open, but they don’t change the path of the airflow.

FastraxTurbo here on NSX Prime dyno tested the impact of the VVIS on a naturally-aspirated NSX. Across a 1700 rpm band in the midrange the VVIS added up to 11.5 hp and across a 500 rpm band at the top of the rev range it cost up to 3.5 hp. As you said, it seems that Honda’s engineers were trying to build a road-drivable GT, not a racer, and the VVIS helps with that.

VVIS_dyno_chart.jpg


If something is really strangling a stock NSX’s engine, it doesn’t seem to be the VVIS system. Getting rid of it only freed up about 3 hp at the redline.

To those commenting that ITB's "only free up air the flow" you're forgetting the the tuned length effect that only comes from a designed trumpet.

I fully agree that resonances are very important. To get the most horsepower out of a naturally-aspirated engine, you have to get the correct airspeed in the intake runners or trumpets at the rpm where you want to maximize power, you need the intake system to resonate at that rpm as well to force even more air into the combustion chambers, you need to make sure the path of the flow is smooth, and that the engine inhales cool air from outside the engine compartment.

As best I can tell, the cross section of the stock intake runners is 1801 mm2, which is equivalent to a 48mm port. The airspeed you get depends on how much air is flowing through there per minute. SoS’s ITBs have a 48 or 50 mm diameter and a throttle plate is in there as well blocking some of the cross section. The airspeed past the throttle spindles is probably similar to the airspeed in the stock runners so that doesn’t look like it’s the key to more horsepower. I’m not sure how the length of the stock runners compares to the ITBs but that will impact the resonant frequencies and therefore the rpm at which torque is boosted. In order to increase the number of frequencies at which the engine gets a torque boost, Honda designed the VVIS system. It does increase the number of rpm at which resonances boost torque but at the cost of a slightly rougher path for the flow when the holes open up. In addition, the air can flow through straight ITBs easier than through the curved OEM intake runners even if they have the same diameter, but I’m not sure how many horsepower the gentle curve of the OEM runners really costs.

With 48 mm ITBs, I’d expect the air to have a slightly less restrictive path but that there would be less rpm at which resonances boost torque. So more horsepower up top but losses at some rpm lower down. I don’t understand the physics of how a pretty much stock 3.0 with ITBs can gain horsepower at all rpm and up to 65 in the midrange - that’s more than you’d get with a CTSC! But if more dyno tests show the same results, the ITBs must work their magic somehow.
 
Great info and presentation greenberet (as usual). Up to 11.5 HP from VVIS over the most used rev range for street driving is not to be sneezed at.

I assume NA1/2 R-GT has the 48mm ITB trumpets? Has anyone dynoed the 50mm trumpets yet?
 
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Dan- Since i was apparently one of those that you feel insulted you, i should comment further. No one was questioning you about the numbers you believe you gained. But with ANY dyno numbers that are not repeated on say three cars are going to be questioned. There are just too many variables on the dyno for us to believe one result, especially when it just sounds too good to be true. Again, in your case the numbers may be totally valid, but until someone like SOS tells us they have seen 41 hp on more than one car, we just have to be skeptical. Again not of your honestly, but of some variable that possibly skewed the result.
I don't know how long you've been around, but the early NA Comptech engines told us that it's REALLY hard to get HP out of this engine NA. They did not have ITB's, but they had bigger cams, valves, head porting, increased compression, and probably several treaks we didn't know about. While many were saying these eingines produced around 360 flywheel, One of the their big boys told me that 345 was optimistic and that was on 100 octane. I took that as meaning 325 was probably a realistic number. I remember more than one owner who spent 30k with Comtech and only got a couple a dozen HP and 3 tenths in acceleration. Point being, veterans will always be questioning excellent numbers. Certainly no "hate" intended. Peace.
 
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