dave22 said:Of course I'm right. Why won't you just listen to me in the first place. Oh yeah, and NeoNSX - while being a cheeky guy at times - is a really funny & valued contributor.
What can I say, the quote never lies.
-
Protip: Profile posts are public! Use Conversations to message other members privately. Everyone can see the content of a profile post.
3.8 litre monster @ Science of Speed
- Thread starter blackcat
- Start date
What can I say, the quote never lies.
guys, this 3.8L engine is badass. instant throttle response, I can't stop driving the car...picked it up on Friday and I've already put around 320 miles on it!
brandonson said:
why do you think that? There wouldn't be a significant change in the piston design to achieve the extra .5 in compression so what would cause it to use oil? 12:1 certainly isn't overly radical, look at the OEMs getting there (porsche, etc) and they have to consider morons putting 85 octane gas in the vehicle. I have seen many street motor builds use 12:1 compression in everything from Hondas to Corvettes and I'm sure the Nsx with it's highly efficient combustion chamber would take to it no problem.
Edmo7.........I'm sure the car drives sweet now, congrats! Good to see people push the envelope.
satx said:
Considering I have been modifying hondas since 1989 I have heard of all kinds of combinations and tried a number of combinations. I ran 12:1 on one of my old Integra GSRs and it consumed oil (blow by) after 25K with a very reputable builder and proper break in. I was going to build another engine with same spec with another builder and he advised against it for the aforementioned reason. He told me on 91-93 pump gas the safest CR for reliability would be 11.1 - 11.5:1. By the way 12:1 will not make much of a difference over 11:1.
ediddynsx said:haha come pick me up for a ride since you love driving
hmmm...maybe I don't love driving it THAT much.... haha j/k
- Joined
- 19 November 2002
- Messages
- 633
ediddynsx said:haha come pick me up for a ride since you love driving
How do I get on the waiting list?!?....I'm in so-cal, will a couple of cold ones do for a 2nd and 3rd gear pull?:biggrin: :wink:
After hearing about SoS’s 3.8 liter package, I was also wondering how much power it will produce and how engine life will be affected. Based on the research I did, it seems to me that:
331 rwhp is a very good figure for a naturally aspirated 3.8 liter NSX engine
In the FAQ section of NSX Prime, typical dynamometer rwhp figures are given for NSXs in various states of tune. The attached picture “SoS horsepower.jpg” gives an overview and comparison to SoS’s 3.8 liter engine.
3.0 liter engines with Comptech’s full naturally aspirated engine modifications typically put out around 90 rwhp per liter of displacement. I assume these engines are about as optimized as an NSX engine can be without completely redesigning the intake system, adding additional knock sensors, etc. SoS's 3.8 liter engine puts out 89 rwhp per liter, so it seems to be a very well developed package already and that significant gains above 331 rwhp will be gravy.
High rev capability and bearing wear of NSX engine should not be affected
The 88 mm stroke crankshaft SoS uses will push the piston up and down further per engine revolution, increasing accelerative forces on the piston (see SoS piston acceleration.jpg below).
However, the decreased mass of the SoS piston almost exactly cancels this out so that the reciprocating force on the crankshaft is virtually the same as in a stock 3.0 engine (see SoS reciprocating force.jpg below). Bearing life and the engine’s willingness to rev should therefore not be negatively affected by the 3.8 liter conversion.
Piston and cylinder wear may be negatively affected
The angle a connecting rod reaches, and therefore the load with which it pushes the piston against the cylinder wall during the power stroke, is greater the longer the stroke of the crankshaft (see SoS side wall load diagram.jpg below).
In the case of the NSX, using a rod of OEM length with an 88 mm crankshaft will increase cylinder wall loading by 13.9% (see SoS side wall load chart.jpg below). For piston and cylinder wear not to increase, these components would have to have better wear characteristics than the OEM parts over the life of the engine. However, if the OEM engine can run hundreds of thousands of miles before needing a rebuild, a little bit less longevity here might be acceptable.
Overall, the 3.8 liter package looks good.
PS: NSX Prime doesn't allow spreadsheets to be uploaded. If someone could host the spreadsheet I used to carry out these calculations, a link could be posted so that others can play around with it as well, in case someone's interested.
- 331 rear wheel hp is a very good figure for a naturally aspirated 3.8 liter NSX engine
- reciprocating forces on the crankshaft and therefore bearing life and the engine’s high rev capability should be almost identical to a 3.0 liter stock engine
- sideways forces on the cylinder wall are higher than in a stock engine, so piston and cylinder wear may be higher over the course of the engine’s life
331 rwhp is a very good figure for a naturally aspirated 3.8 liter NSX engine
In the FAQ section of NSX Prime, typical dynamometer rwhp figures are given for NSXs in various states of tune. The attached picture “SoS horsepower.jpg” gives an overview and comparison to SoS’s 3.8 liter engine.
3.0 liter engines with Comptech’s full naturally aspirated engine modifications typically put out around 90 rwhp per liter of displacement. I assume these engines are about as optimized as an NSX engine can be without completely redesigning the intake system, adding additional knock sensors, etc. SoS's 3.8 liter engine puts out 89 rwhp per liter, so it seems to be a very well developed package already and that significant gains above 331 rwhp will be gravy.
High rev capability and bearing wear of NSX engine should not be affected
The 88 mm stroke crankshaft SoS uses will push the piston up and down further per engine revolution, increasing accelerative forces on the piston (see SoS piston acceleration.jpg below).
However, the decreased mass of the SoS piston almost exactly cancels this out so that the reciprocating force on the crankshaft is virtually the same as in a stock 3.0 engine (see SoS reciprocating force.jpg below). Bearing life and the engine’s willingness to rev should therefore not be negatively affected by the 3.8 liter conversion.
Piston and cylinder wear may be negatively affected
The angle a connecting rod reaches, and therefore the load with which it pushes the piston against the cylinder wall during the power stroke, is greater the longer the stroke of the crankshaft (see SoS side wall load diagram.jpg below).
In the case of the NSX, using a rod of OEM length with an 88 mm crankshaft will increase cylinder wall loading by 13.9% (see SoS side wall load chart.jpg below). For piston and cylinder wear not to increase, these components would have to have better wear characteristics than the OEM parts over the life of the engine. However, if the OEM engine can run hundreds of thousands of miles before needing a rebuild, a little bit less longevity here might be acceptable.
Overall, the 3.8 liter package looks good.
PS: NSX Prime doesn't allow spreadsheets to be uploaded. If someone could host the spreadsheet I used to carry out these calculations, a link could be posted so that others can play around with it as well, in case someone's interested.
Attachments
what are your opinions on a 3.2 upgrade to a 3.8??
as far as wear, would a higher grade oil like racing oil prevent this as compared to Mobile 1 super synthetic, like a Shell racing oil or so?
as far as wear, would a higher grade oil like racing oil prevent this as compared to Mobile 1 super synthetic, like a Shell racing oil or so?
greenberet said:
hi Andreas --
Someone's been doing their research.
A couple notes:
Based on prior results on the dyno used, the rating of this engine is 380 bhp. This is a 110 hp increase over a full stock car. 110 hp increase is incredible especially at a low 10.5:1 compression ratio, and we're looking at some intake mods to improve this even more. However, the beauty of the engine is the torque gains and delivery in the RPM range.
We're working on creating graphs comparing this engine to a stock & supercharger setup, but in summary:
1. this engine creates more torque at 3000 RPM than a stock 3.0L NSX creates at PEAK.
2. this engines creates more torque at 4000 RPM than our previously highest producing 3.3L engine does at PEAK.
3. this engine creates more torque at 5000 RPM than a Comptech Supercharger does at PEAK.
4. this engine creates about 25 more lb/ft at peak than a Comptech Supercharger.
This engine produces about as much horespower as a standard Comptech supercharger. Torque is what you actually feel and perceive as acceleration. The acceleration and pull of this engine is unlike anything I've felt before.
Regarding your engine dynamics research, I'd agree on reciprocating force. The force generated by the stroker package is no different than a stock engine due to the weight reduction of nearly 100 grams PER CYLINDER that we were able to achieve.
I'm unsure how you determined your side wall load numbers, however, I think your numbers do not take into account the lower mass of the piston and that the centerline of the wrist pin is not in the same relative position relative to the top of the piston as factory which allows us to maintain a good rod ratio for high engine speed operation.
Thank you for charting these. They look great!
By the way, the engine in discussion can be found here:
http://www.scienceofspeed.com/produ.../custom_engine_program/custom_engine_program/
We sell this as a component package for $8165.00 or $15445.00 as a turn key package (IE. you drop off your car or drop off your engine, and you get a complete engine ready to install in exchange.)
This car & customer was a joy to work with. I hope one day you will all be able to see it in person. This has been my favorite and most impressive car we've had in our shop.
Cheers,
-- Chris
Dan, in my humble opinion, a 3.2 to 3.8 liter upgrade sounds good as well, it will just give a somewhat lower percentage gain than a 3.0 to 3.8 liter conversion would.
I'm not aware of any oils that will reduce wear more than Mobil 1, Redline, etc. multiviscosity oils do. I'd think that straight weight racing oils will usually increase wear overall because they don't lubricate the engine as well at start-up, when the oil is cold.
Chris, as far as I can tell, the side wall load is determined by the angle the connecting rod reaches compared to the cylinder wall during the power stroke. If the centerline of the wrist pin is offset to the side of the piston, this could reduce the angle and therefore the wall loading. If you have data regarding the wrist pin offset of your 95mm pistons compared to the OEM 90 and 93mm pistons, I'd gladly run some numbers (or send you the spreadsheet for you to look it over and play around with it).
I hope to be able to see and maybe drive the car sometime. On the Autobahn recently, I was unable to overtake a BMW 5 series without downshifting. And it does take a pretty long stretch of road to run into the rev limiter in fifth (my top gear). :smile:
I'm not aware of any oils that will reduce wear more than Mobil 1, Redline, etc. multiviscosity oils do. I'd think that straight weight racing oils will usually increase wear overall because they don't lubricate the engine as well at start-up, when the oil is cold.
Chris, as far as I can tell, the side wall load is determined by the angle the connecting rod reaches compared to the cylinder wall during the power stroke. If the centerline of the wrist pin is offset to the side of the piston, this could reduce the angle and therefore the wall loading. If you have data regarding the wrist pin offset of your 95mm pistons compared to the OEM 90 and 93mm pistons, I'd gladly run some numbers (or send you the spreadsheet for you to look it over and play around with it).
I hope to be able to see and maybe drive the car sometime. On the Autobahn recently, I was unable to overtake a BMW 5 series without downshifting. And it does take a pretty long stretch of road to run into the rev limiter in fifth (my top gear). :smile:
Last edited:
I won £10 on the lottery on Saturday, i'm getting there!
Hi Chris, have you guys tried using bigger throttlebody with this engine setup? I'd imagine throttle body kit like the one using Infiniti Q45 throttlebody could benefit since the displacement is so much more.
Overall, impressive results I think.
Ak
Overall, impressive results I think.
Ak
hi Akio --
Yes, it would be possible to cut and weld the intake manifold to accept a larger throttle body. This will require stand alone engine management.
Cheers,
-- Chris
Yes, it would be possible to cut and weld the intake manifold to accept a larger throttle body. This will require stand alone engine management.
Cheers,
-- Chris
ak said:
Well, better:
http://www.scienceofspeed.com/produ...Speed/individual_throttle_bodies/assy-800.jpg
http://www.scienceofspeed.com/produ...SX/ScienceofSpeed/individual_throttle_bodies/
Although we are working on a new single throttle body & manifold design for street cars as well.
If you are interested in this? Please note our special:
http://www.nsxprime.com/forums/showthread.php?t=63976
As well as some write ups here:
http://www.nsxprime.com/forums/showthread.php?t=63843
Cheers,
-- Chris
http://www.scienceofspeed.com/produ...Speed/individual_throttle_bodies/assy-800.jpg
http://www.scienceofspeed.com/produ...SX/ScienceofSpeed/individual_throttle_bodies/
Although we are working on a new single throttle body & manifold design for street cars as well.
If you are interested in this? Please note our special:
http://www.nsxprime.com/forums/showthread.php?t=63976
As well as some write ups here:
http://www.nsxprime.com/forums/showthread.php?t=63843
Cheers,
-- Chris
Edmo7 said:
Step 1: 3.8 displacement kit
Step 2: Throw bolt-ons back on
Step 3: CTSC ? :biggrin: chris@SoS ...is it possible?
I just emailed Chris at Science of Speed about the 3.8 liter conversion.
Here's his answer's to my questions:
What is the HP increase on a 1991 NSX?
You can see dyno results here:
http://www.nsxprime.com/forums/showthread.php?t=63843
How many days does this service take?
Once we have all parts, work takes about 2-3 weeks.
How many miles is a good time to perform this service? I currently have 90K on my 91?
Any mileage is a good time, this really is not very important since the engine is basically completely refreshed. We have done engines between 18k - 150k miles.
If I purchase just the Engine Component Package for $8,165.00, can most Acura dealers perform this service?
If you have the Acura dealer remove the engine and send it to us, then yes, a normal Acura dealer could be used, however, if it were my car, I would take it to a specialists.
®
Here's his answer's to my questions:
What is the HP increase on a 1991 NSX?
You can see dyno results here:
http://www.nsxprime.com/forums/showthread.php?t=63843
How many days does this service take?
Once we have all parts, work takes about 2-3 weeks.
How many miles is a good time to perform this service? I currently have 90K on my 91?
Any mileage is a good time, this really is not very important since the engine is basically completely refreshed. We have done engines between 18k - 150k miles.
If I purchase just the Engine Component Package for $8,165.00, can most Acura dealers perform this service?
If you have the Acura dealer remove the engine and send it to us, then yes, a normal Acura dealer could be used, however, if it were my car, I would take it to a specialists.
®
I must say that I am impressed by the results of the SoS 3.8 liter conversion. Personally, I would prefer a normally aspirated engine above a turbo or supercharged one.
I wonder if there are any results known as to how this upgrade translated the performance of the NSX in question. As in 0-60, 0-100 mph and further times. I am very curious about those. Could we expect better figures as with for example a CTSC, since the torque is more or less always ready on the NA-engine ??
I wonder if there are any results known as to how this upgrade translated the performance of the NSX in question. As in 0-60, 0-100 mph and further times. I am very curious about those. Could we expect better figures as with for example a CTSC, since the torque is more or less always ready on the NA-engine ??
This has definitely got me thinking:smile:
Just curious, would a CTSC with the 3.8 motor work well or is it too much over the top?
I could only imagine what it might feel like if this was possible
Just curious, would a CTSC with the 3.8 motor work well or is it too much over the top?
I could only imagine what it might feel like if this was possible
- Joined
- 18 July 2005
- Messages
- 2,636
spyderplayer2002 said:
Where are you getting those numbers? At 230whp, thats a 21 percent drivetrain loss. With a mid engined car, that's not exactly believable.
- Joined
- 4 November 2005
- Messages
- 316
SilverStone05 said:
Those number were just an estimate, sorry if you can't believe me.
Edmo7 your car is such a perfect sleeper! I love it!
Similar threads
- Locked
- Locked
- Locked