NSX Engine Build

[Stevon]

I'm looking to build a reliable NA engine with a little more power and have a few questions. Have built about 50 engines in my life from Chevy to BMW and 911 Porche racing engines (SCCA 2.0 ltr class). My 95 engine has a weak cylinder and it's time to plan a new engine. Rather than lay out $15 grand or so to SOS for a nice stroked engine, I plan to do some of the engineering, parts gathering and assembly myself. No sense paying someone else to do what I know how to do. Besides it's fun to build engines once you understand the prinicples and have learned from a couple of failures .
Thinking of Benson sleeving block and having him fit bore to 95mm pistons. Also considering buying an 86 to 88mm stroker crank then use stock rods. The early Comptech Strokers used a similar setup so it is a proven concept. In doing the calculations for buying the correct pistons I need the C30-C32 deck height which I have not been able to find published anywhere. Anybody know what this measurement is? Also, what brand of pistons are recomended? I'm familiar with Mahle-Kolbenschmit pistons. Ideas on machining, cylinder head work, cams, tuning etc. please throw in your ideas. Looking for a value rebuild with a little more oomph! than stock. Thanks everybody!
Stephen

 

[crx-nsx]

Not many people will reply. Most of nsx owners send theirs out due to pain in the but to deal with when it comes to NSX engines. I hope you have good luck. I wanted to build mine as well and still debating. I am in the same boat as you are with building or wanting to.

 

[gsrboy]

Benson does a good job sleeving engines. I wouldnt go with 95mm right off the bat though. It will give you less room for errors and rebuild. If you did get a stroker crank you will need to get custom pistons and rods that will work with the setup. This requires alot of measurements and would probably be better off getting a stroker kit that comes with the proper rods and piston for the setup.

 

[A.S. Motorsport]

What are you goals in terms of specs en performance.
It be best to outline that and work toward a good setup from there.

A 500HP ITB engine compared to a 350 HP will require different levels of tune and parts, for example what octane rating are you looking to use?
Will the car be a daily driver?

 

[Stevon]

Looking to build a NA streetable motor with more torque and around 350 or so horsepower. 91+ octane and 11.0:1 to 11.4:1 compression, Maybe Cams (not much gain, kills emissions). Cams would also change compression ratio. Live in California so emissions are always an issue with visible modifications (ITB). I realize with the increased displacement OEM computer ECM probably won't be able to keep up with and/or be modified for this application. Have no experiance tuning Honda proprietary ECM code, haven't heard of anyone who can. An aftermarket ECM is an option but I definately want to keep traction control and maybe a knock sensor. Aftermarket knock sensor is available http://www.jandssafeguard.com/ . Aftermarket traction control? no clue there. I plan to use stock rods and stroker pistons. I'm only adding +5mm stroke (1/2 of 10mm) on top of crank journal. Just have to order the correct pin height pistons. This has been done before, think Comptech used this setup in their stroker kit. For calculations I need the C30A deck height which nobody seems to know or is willing to tell me. So far I missed out on a $600 long block core that snipesusaf sold a few weeks ago. It's a long road to finish this project, like the car itself. Just doing my homework before I make the next move. Car drives OK, weak #5 cylinder at 145 psi, tiny amount of oil soot buildup on exhaust tips but otherwise drives OK, not using much oil. Rebuild can take a year or two.

What are you goals in terms of specs en performance.
It be best to outline that and work toward a good setup from there.

A 500HP ITB engine compared to a 350 HP will require different levels of tune and parts, for example what octane rating are you looking to use?
Will the car be a daily driver?

 

[RYU]

Some threads you might find interesting.

SR5GUY is showing promising signs accessing the stock ECU - http://www.nsxprime.com/forum/showthread.php?t=143407

Mac Attack might know your deck height question - http://www.nsxprime.com/forum/showthread.php?t=154927

Looking for a streetable motor with more torque and around 350 or so horsepower. 91+ octane and 11.0:1 to 11.4:1 compression, Maybe Cams (not much gain, kills emissions). Cams would also change compression ratio. Live in California so emissions are always an issue with visible modifications (ITB). I realize with the increased displacement OEM computer ECM probably won't be able to keep up with and/or be modified for this application. Have no experiance tuning Honda proprietary ECM code, haven't heard of anyone who can. An aftermarket ECM is an option but I definately want to keep traction control and maybe a knock sensor. Aftermarket knock sensor is available http://www.jandssafeguard.com/ . Aftermarket traction control? no clue there. I plan to use stock rods and stroker pistons. I'm only adding +5mm stroke (1/2 of 10mm) on top of crank journal. Just have to order the correct pin height pistons. This has been done before, think Comptech used this setup in their stroker kit. For calculations I need the C30A deck height which nobody seems to know or is willing to tell me. So far I missed out on a $600 long block core that snipesusaf sold a few weeks ago. It's a long road to finish this project, like the car itself. Just doing my homework before I make the next move. Car drives OK, weak #5 cylinder at 145 psi, tiny amount of oil soot buildup on exhaust tips but otherwise drives OK, not using much oil. Rebuild can take a year or two.

 

[BATMANs]

....Thinking of Benson sleeving block and having him fit bore to 95mm pistons. Also considering buying an 86 to 88mm stroker crank then use stock rods. The early Comptech Strokers used a similar setup so it is a proven concept. In doing the calculations for buying the correct pistons I need the C30-C32 deck height which I have not been able to find published anywhere. Anybody know what this measurement is? Also, what brand of pistons are recomended? I'm familiar with Mahle-Kolbenschmit pistons. Ideas on machining, cylinder head work, cams, tuning etc. please throw in your ideas.....

Did you see my combined thread with Mac Attack?

As far as piston brands goes, my decision comes from past experience, research, and talking to engine machine shops that have been around for decades, not just a few years.

I went with the Wiseco 2618 piston. They should have the proper dimensions on file and can probably build to your custom specs.

Since my engine projects are forced induction I went with the 2618 alloy piston.

For your application the best option would be 4032 forged alloy since it's lighter and like the OEM cast piston, doesn't grow or contract like the 2618 pistons. Growth and contraction of the pistons tend to contribute to a little more piston noise while cold, more oil consumption (since the piston needs to warm up and grow into the combustion chambers) and a little more wear and tear due to piston slap.

JE and Wiseco are under the same company now, but Wiseco has the edge in workmanship and more years in top fuel and F1 applications.

CP piston founder was suppose to be an ex -employee of JE pistons. It's suppose to be of better quality build from what I've heard.

Diamond Pistons are good too. They are known for their billet pistons which I think is made from 7075 alloy (strongest for pistons that I've seen so far). They are used in the Koenigsegg Agera R.

I looked into Mahle and there was nothing about them (certainly for the price) that compelled me to use them for my projects.

For an all engine project I would model after the compression ratio of a GT3-RS 4.0, which I heard was 12.6:1.

Also cleaning up the ports and doing a 3 angle valve job like my project.

 

[Stevon]

Batmans,

Yes I did see your thread, alot to read in one sitting. Tons of useful tips! per chance do you know the C30A deck height measurement ? 12.6 to 1? on 91 octane gas? I would only consder that with a cam upgrade. Right now need to get a core for a reasonable price with shipping. They're around, just have to be patient until I find a deal.
My main focus at this time is to buy a house right now with the low interest rates available. It is not easy to buy a house in San Diego. 90% of the houses for sale are owned by the local banks and they are not accepting any type of loans, they want cash only! My FHA loan approval has become useless in this bank controlled market here. They also are "choking" the market by only listing 4 new properties a week even though they own 30% of all realestate here. So currently I am busy looking at houses and putting in offers. The engine upgrade will be a slow process I'm sure under the circumstances.

 

[Honcho]

Just a couple more things to consider. When increasing displacement, the real big $$$ is the stroker because you need a new crankshaft and rods, which are very expensive to fabricate. Instead, sleeving the block and running as big pistons as possible will allow you to use the factory crank and rods, saving considerable money. Batman's info is great, and I would just add that I have always liked Ross pistons too (from my Mopar days)- very high quality product.

Rather than make your own, I would strongly consider just going with the SOS 95.5mm pistons in 11.5 compression. They have already done all the homework/research and proivde a bolt-on product that is lighter than factory. Going this route may save you a lot of time and money as opposed to having a company go through trial and error with a custom fab (using your engine as a guniea pig btw).

The only issue I have with the SOS pistons is the 2618 alloy. Batman is right- 2618 is super-strong, but will expand and contract inside the cylinder, leading to oil consumption and piston slap noise. High-power nitrous drag guys and turbo guys like the 2618 because it is so strong and less likely to crack, so they live with the oil and noise issues. I agree that 4032 is a better solution for a NA street car on pump gas. Like OEM, 4032 uses silicon in the alloy to harden the metal- this reduces expansion but does make the piston more brittle. However, if you're not strapping a huge blower to the engine or running nitrous, it doesn't matter. I wonder if SOS can get their pistons in 4032?

Anyway, this is what I would do (and may do when I max out my car at the track in a few years lol):

Benson sleeves
SOS 95.5mm pistons (4032?)
RDX Injectors + Prospeed ECU custom tune
Big Bore Throttle
Extrude Honed Intake Manifold
3 angle valve job
MLS head gaskets
ARP head studs
ATI damper pulley
Balance and Blueprint

Adding a stroker will add about $6,000 to the above tab.

 

[BATMANs]

Batmans,

Yes I did see your thread, alot to read in one sitting. Tons of useful tips! per chance do you know the C30A deck height measurement ? 12.6 to 1? on 91 octane gas? I would only consder that with a cam upgrade. Right now need to get a core for a reasonable price with shipping. They're around, just have to be patient until I find a deal.
My main focus at this time is to buy a house right now with the low interest rates available. It is not easy to buy a house in San Diego. 90% of the houses for sale are owned by the local banks and they are not accepting any type of loans, they want cash only! My FHA loan approval has become useless in this bank controlled market here. They also are "choking" the market by only listing 4 new properties a week even though they own 30% of all realestate here. So currently I am busy looking at houses and putting in offers. The engine upgrade will be a slow process I'm sure under the circumstances.

I dun know the engine details. I'm more of a high level thinker. Sorta like a VP or C level person if ya catch my drift.

Be VERY careful in deciding on the cams. I can't tell u how many times I've seen engine projects yield terrible results (less power, more emissions, NVH goes up, etc.).

And I would probably hold off on buying until the "last" round of foreclosures that the media (obama supporters) and banks (obama supporters) are holding off until the elections are completed.

My prediction is that next year will be worse than 2008.

 

[Stevon]

Batmans,

Here is what I'm thinking:

Benson sleeves bored to 95.0mm
custom 95.0mm pistons 4032 alloy, 11.5:0 Diamond or Wiseco
Stroke crank +10mm to 88mm
OEM ECU custom tune with model X ODB2 injectors?
DC sport headers
Adjustable Cam gears
Pro speed 3 core CATS
Big Bore Throttle (available 95-96 throttle by wire?)
polish Intake Manifold
port and polish heads
3 angle valve job
MLS head gaskets
ARP head studs
Billet oil pump gears

As for the house purchase I will buy as soon as I can. Tennant will help with Mortgage and taxes. Problem is there is nothing to buy within 25 miles of where I live now. Seems obsurd but it is true, have done the leg work to see what is really for sale and what is not for conventional home loans.

 

[BATMANs]

Batmans,

Here is what I'm thinking:

Benson sleeves bored to 95.0mm
custom 95.0mm pistons 4032 alloy, 11.5:0 Diamond or Wiseco
Stroke crank +10mm to 88mm
OEM ECU custom tune with model X ODB2 injectors?
DC sport headers
Adjustable Cam gears
Pro speed 3 core CATS
Big Bore Throttle (available 95-96 throttle by wire?)
polish Intake Manifold
port and polish heads
3 angle valve job
MLS head gaskets
ARP head studs
Billet oil pump gears

As for the house purchase I will buy as soon as I can. Tennant will help with Mortgage and taxes. Problem is there is nothing to buy within 25 miles of where I live now. Seems obsurd but it is true, have done the leg work to see what is really for sale and what is not for conventional home loans.

I'm not an expert in sleeves since I haven't gone that route, but have you considered Darton?

Why not take the Compression Ratio up to 12.6:1 since it seems like u won't be going the Forced Induction route? Good call on the 4032 alloy.

I have B&B (aka RM racing) headers. I choose them since they have the WIDEST collectors for any headers (2.5"). If you order from them directly $1400~ just ask them to put the O2 bung right at the collectors before the sleeve joint.

I didn't do any Billet gear oil pump upgrade. I use Pennzoil Ultra Synthetic which Ferrari uses and when the engine was pulled apart the internals, including the oil pump looked like it was almost new.

On the manifolds and head porting, just clean up the ports where you debur and take out the casting imperfections. Match the alloy cast to the valve seat so there is no turbulence in that area. The vain that splits the air for each of the valves - sharpen them for a smoother and quicker airflow.

Find out how much is polishing the ports and compare it to the price of ceramic and thermo dissipation coatings. I'm guessing it's about the same price. There are more benefits with the coatings since u can control thermo dynamics in the heads where the heat dissipation is accelerated and also containing the heat in the exhaust ports so that you maintain exhaust port velocities (when exhaust air cools down it contracts and slows down the exhaust velocities as a result).

What's your reasoning with those aftermarket cats?

Is it to minimize exhaust smell for everyday usage? If it's just that then ur fine.

If you intend to pass the CA smog tests (that get tougher and tougher) then you will need to consider CA legal cats like the Magnaflow 39000.

If you are like me I have full open exhaust for all the time and custom made Magnaflow cats for smogging the car.

 

[Stevon]

Darton sleeves are another $700 or so than the Bensons for one reason. My car is lowered 1" and is hard to get underneath. Two different SMOG techs (Vietnamese and Cambodian, both loved the car) did not care about the headers or Cats and I am passing with 91K on the engine, weak cylinder and the prospeed cats. I think you are right about the CAMs, Acura already did them right. A little more lift in VTEC would be nice but at $3K for marginal gain, I must forgo that choice. 12.6:1 on 91 octane hmmm, I don't want to hammer this motor to pieces, will require a lot of research to consider going higher than what SOS recomends for NA motors. Mazda has come up with a special piston, direct injection and intake/exhaust maifold to allow 14.0:1 compression without excessive knocking. Read this interesting article: http://www.mazda.com/mazdaspirit/skyactiv/engine/skyactiv-g.html
Headers are another question, Just have working ones now that pass emmisions and the car idles smoothly, will require some more research. I do want more torque so giant header tubes could hurt me there. It's a daily driver and needs low end torque to improve especially with the terrible 5 spd trans 1st to 2nd gear spread. It's a PTA to drive around town, especially with the worn motor. I'm sure others would agree. Porting sounds like fun, I haven't done any of that in 25 years! Have the tools and some experience, thanks for the technique tips. I'll keep compiling a list of options and make final descisions as I approch the final build. This is really fun for me, my friends think I'm nuts but I am from another generation I suppose. Can't wait to get my hands on a core motor but there are bills to pay too!

I'm not an expert in sleeves since I haven't gone that route, but have you considered Darton?

Why not take the Compression Ratio up to 12.6:1 since it seems like u won't be going the Forced Induction route? Good call on the 4032 alloy.

I have B&B (aka RM racing) headers. I choose them since they have the WIDEST collectors for any headers (2.5"). If you order from them directly $1400~ just ask them to put the O2 bung right at the collectors before the sleeve joint.

I didn't do any Billet gear oil pump upgrade. I use Pennzoil Ultra Synthetic which Ferrari uses and when the engine was pulled apart the internals, including the oil pump looked like it was almost new.

 

[BATMANs]

Also, you have a couple of options with regards to piston skirts.

My project and the OEM pistons are "full skirts".

SOS sells the partial skirt piston.

If I were building an all engine project I would use a partial skirt since it's lighter than the full skirt due to less materials being used.

Did you consider Ferrea valves? They are forged and lighter and the neck of the valve are undercut to allow more flow.

By keeping the material masses down u can potentially by ur self some extra legroom in case you were to mis-shift, for example.

Free up power is another benefit.

 

[Stevon]

Batmans,

Why not just poppet valves like Indy cars? Lol. I will consider Ferrea valves, use same valve springs? Brian Crower lists the NSX C30A stock measurements as 91.11mm Bore x 76mm Stroke - 8.287" Block Height. Guess I can confirm measurement of the deck height when I get the core dissasembled. The next step may sound crazy.... Weld and offset grind the crank then Nitride it and balance assembly! I know some of you will be horrified but hear me out. Figure that if it is good enough for blown dragsters pushing 1000HP plus, it's good enough for a mild NA upgrade engine. Let the nay sayers begin! Already have a quote from reputable shop for the job. Crank has room enough to add +5mm without reinforcing the cheeks yielding 88mm stroke. Stock stroke is quoted as both 76mm and 78mm? Take a look at picture of a stock NSX crank.
CORRECTION Brian Crower specs listed for MITSUBISHI EVOLUTION IX 4g63 on page 7, not NSX (no specs listed for deck height)

 

[Honcho]

Here are some numbers from the 1991 service manual:

Cylinder Bore (new)(mm): 90.00 to 90.02
(Service Limit): 90.07

Stroke: 78 mm

 

[BATMANs]

Batmans,

Why not just poppet valves like Indy cars? Lol. I will consider Ferrea valves, use same valve springs?......

Ferrea are poppet valves. I did use the OEM double valve springs. Everything was within specs and if I recalled they were at 90lbs to compress. Aftermarket ones tend to have greater spring compression which robs power. There was nothing prior to the engine build that if felt warranted replacing the springs.

 

[Stevon]

Batman,
Ah yes, what I ment was camless valving using air or electric solonoids to open the valves. Pneumatic actuators have been used in F1 for a few years now: http://scarbsf1.com/valves.html and http://autospeed.com/cms/title_Camless-Engines/A_0910/article.html . Imagine tuning lift and duration through a laptop? Race track one profile, local emisions another, Imagine the potential...and the cost!
Stephen

 

[BATMANs]

Batman,
Ah yes, what I ment was camless valving using air solonoids to open the valves. Pneumatic actuators have been used in F1 for a few years now: http://scarbsf1.com/valves.html and http://autospeed.com/cms/title_Camless-Engines/A_0910/article.html . Imagine tuning lift and duration through a laptop? Race track one profile, local emisions another, Imagine the potential...and the cost!
Stephen

I thought that is what you meant.

The German guy that designed it has a Zonda or 2.

Bastard he is.....

 

[Stevon]

Closed on duplex on Novemer 9th! The construction is going slow due to FHA 203k rules (5 inspections, 5 draws) but at least I own land!
I'm still working the numbers for the build. A good plan and carefull calculations are essential when you go outside factory specs and/or a proven design. Purchased an already sleeved block that was bored to 84mm, yes you read that right! It was raced and ate all 6 pistons pretty much the same way. The pistons appear to be melted and probably the engine was run too lean. The story goes that seller built and offered to setup/tune the engine. The Buyer used forced induction and someone else for the tune so there was no way he could warranty his engine build work. Complete engine with heads, cams etc. was listed in eBay and we negotiated the price a little over 2K for everything. He shipped it out Greyhound freight and it arrived without damage in 3 plastic boxes dissaembled. Everything is there, sleeving alone was $1800! So I now have an affordable core to build

 

[Honcho]

Awesome! Excitied to see where this goes. Are you sure about the bore? Stock bore is 90 mm, so did they under bore this engine to 84 mm?

 

[Stevon]

Check out RS Sleeves attachment, yes my block bores are sleeved and 84mm, I guess with the blower they didn't need displacement, also may have had SCCA limits to be under 3.0 Liter, who knows. The guy I bought it from wasn't talking, only a few hints to the history of this engine. I'm sure sombody knows, not important. I came up with the Idea of stroking crank to 90mm. It's only another milimeter to add to the crank. The Brian Crower stroker crank is 94mm. I think that It might not work with the stock rods I want to use. Piston Manufacturer will let me know if they can make a piston that could facilitate another milimeter up in the ringland. I'm unemployed again (consultant norm) so there is no extra cash to move forward. But there still is math to complete and a piston supplier to find for now, Check my figures:

SOS published deck height range: 8.720 - 8.712 or 221.488mm - 221.285mm
NSX titanium connecting rod specifications:
C30a/C32b
(5.984") length center to center 152mm = 5.9843"
C30A Big End Diameter 2.0866" 53mm
C32B Big End Diameter 2.1654" 55mm
C30A Pin End Bore Diameter 22mm
C32B Pin End Bore Diameter 23mm
Big End Width 0.800"
Pin End Width 0.878"

Bore = 95mm = 3.74016"
stroke = 88mm = 3.46456"
Piston pin diameter: ø22mm (C32B standard ø23mm)
Rod L. = 152mm = 5.9843"
Gasket = 95mm x 1.2mm (for arguments sake)

Compression height = 0.5 X stroke + rod length + piston-deck clearance - block height
1.7323 + 5.9843 + 0.0 - 8.720 = neg -1.0034 piston compression height
Piston Compression Height: neg -1.0034"

Calculate your engine displacement by taking the square of the bore divided by 4,
multiplied by pi, multiplied by the stroke, multiplied by the number of cylinders:
((Bore X Bore) / 4) X pi X Stroke X Cylinders
3.74016 x 3.74016/ 4 x 3.141592654 x 3.46456 x 6 = 228.3860 CI
95 x 95/ 4 x 3.141592654 x 88 x 6 = 3742579.3287102
3.743 Liters

calculation in CI for determining compression ratio:
CR=(D + PV + DC + G + CC) / (PV + DC + G + CC)
CR = Compression Ratio
D = Displacement. Bore x Bore x stroke x 0.7854
PV = Piston Volume. Negative (dish or valve pockets) Positive (dome)
DC = Deck Clearance Volume. Bore x Bore x 0.7854 x Distance between Piston and Deck at TDC
G = Gasket Volume. Bore x Bore x 0.7854 x Compressed Gasket Thickness
CC = Head Combustion Chamber Volume. (in CC convert to CI)


CC = 45.4cc (Calculated not measured) plus gasket volume
G = 8.5cc (Calculated not measured) gasket volume

Total CC = 53.9 cc



Swept Volume (cc) = bore diameter (mm) x bore diameter (mm) x stroke (mm) x .0007854
Swept Volume (cc) = 95 x 95 x 88 x .0007854
Swept Volume (cc) = 623.7647

Compression Ratio = (swept volume total chamber volume) /total chamber volume.
Compression Ratio = (623.7647) / 83.9
Compression Ratio = 11.5726 : 1

I just don't have enough information to make an acurate calculation at this time, still looking.