V6 engine questions

[JD Cross]

Not sure if this is the right forum but I have some questions for knowledgeable engine guru's

Our NSX engines are 90 degree V6's which I understand are harder to balance and that a 60 degree V6 is a smoother running configuration.
That makes me wonder why the new V6 turbo Formula 1 engine for 2014 is to be a 90 degree configuration.
Can anyone explain this?

Secondly does anyone know if the new NSX 3.5L will be a 90 or 60 degree V6?
If the new NSX is to have a 60 degree configuration, the current J series has an 89 mm bore and 93 mm stroke which would not be a high revving setup like the C series.
Do you think Honda will build a new 60 degree V6 with a bore of say 93-95 mm for the new NSX

Looking forward to your comments

Thanks
Jim

 

[dablackgoku1234]

Not sure how accurate this info is going to be, but according to the wiki, the 2015 NSX will sport a 2.1L 90 degree V6 with DOHC labelled a Z21A.

C-series - 90° DOHC
1991–1996 3.0 L C30A (NSX)
1997–2005 3.2 L C32B (NSX)

EarthDreams Z-series - 90° DOHC
2015+ 2.1 L Z21A(EarthDreams) 2015 Acura NSX

 

[Honcho]

90 degree is not necessarily bad for balance. The main reason Honda went to 60 for the J is compactness. Like all J-series V6 engines, the NSX J35XX will be 60 and will share the block casting with the RLX J35Y3. So, it is not really a "new build" for the NSX, but it will be hand assembled on a separate line with different internals and heads unique to the NSX. Still no word on DOHC, but it is likely the heads will use a performance-tuned version of the SOHC VTEC system from the J35Y3, which applies VTEC to both intake and exhaust valves.

 

[dirtbag]

What makes things interesting is the 2014 V6 turbo Formula 1 engine is NOT a split-pin crank design (correct me if I'm wrong).

 

[BATMANs]

This is a great question and could be potentially a great thread.

Here's what I found:

http://www.caranddriver.com/features/the-physics-of-engine-cylinder-bank-angles-feature

 

[JD Cross]

90 degree is not necessarily bad for balance. The main reason Honda went to 60 for the J is compactness. Like all J-series V6 engines, the NSX J35XX will be 60 and will share the block casting with the RLX J35Y3. So, it is not really a "new build" for the NSX, but it will be hand assembled on a separate line with different internals and heads unique to the NSX. Still no word on DOHC, but it is likely the heads will use a performance-tuned version of the SOHC VTEC system from the J35Y3, which applies VTEC to both intake and exhaust valves.

Honcho

The J35Y3 is a 89.7 mm (3.5 in) x 92.3 mm (3.6 in) bore and stroke. This long stroke engine would reach a max piston speed of 25 m/s about 8100 rpm. Our current 78 mm stroke engines only reach about 21 m/s at 8100 rpm so are much less stressed.
Why would you see Honda going long stroke J series instead of short stroke oversquare for the NSX 2.0

Jim

 

[sparky]

This is a great question and could be potentially a great thread.
Here's what I found:
http://www.caranddriver.com/features/the-physics-of-engine-cylinder-bank-angles-feature

I assume the NSX C30/C32 V6 was designed at 90 degrees for two reasons (1) reduced overall engine height, to support low slung body design and (2) to reduce vibrations as described in the article above. As I understand the NSX crank has slightly offset conrod journals that allow 120 degree firing despite the 90 degree configuration.

 

[JD Cross]

Can anyone shed any light on why a long stroke 60 degree V6 for the NSX 2.0 instead of a 90 degree unit?
You would think they have the tooling for both configurations

Jim

 

[Honcho]

The reason why is cost sharing with RLX. Also, a turbo is rumored so rpms may be lower than the C30A.

 

[RYU]

Great thread.

I'm curious about the upper sensible limit of the stroked C30As and C32Bs running around.

If the J series has a 89mm bore and 93mm stroke with a lower redline... the C30A has a stock 90mm bore and 78mm stroke at 8200 redline... and a stroked (e.g. SOS 3.5L) is at 93mm x 86mm is theoritically at the same redline... I'm just wondering how much stress can these stroked NSX motors take or are they still within a safe threshold.

 

[JD Cross]

RYU

My understanding is that mean piston speed is one of the limits on engine rpm and intake velocity is another. The forces on the connecting rod and piston to stop the upward motion of the piston on the exhaust stroke are the highest and so determine the mechanical rpm limit of the design and materials used.The intake flow velocity is about valves,intake ports and other things I don't understand but if the intake flow can't keep up with the engine's needs then flow will be the rpm limiter.

I've read that mean piston speed in F1 engines is in excess of 25 meters/sec. Sporting engines will run from 20-25 meters/sec.
Our C30 engines at 8200 rpm are at 21.3 meters/sec which suggests good reliabilty at that redline
The J series at 8200 rpm would be 25.4 meters/sec apparently at the upper limits for a street engine.
The J series engine would need to redline at 6875 rpm to keep a mean piston speed of 21.3 meters/sec - the same as our C30 speed at its redline of 8200 rpm.

If Honcho is right about Honda wanting to use the J series architecture for cost reasons, then it seems to me that the rumour of a turbo J series has some possibilty.
A turbo J series could reach a target hp rating of say 400 without having to make it's power on rpm alone.
I'm not knowledgeable on FI but perhaps those who are could advise if it would be possible to reach up to 500 hp with a redline of 6500 rpm?

Jim

Great thread.

I'm curious about the upper sensible limit of the stroked C30As and C32Bs running around.

If the J series has a 89mm bore and 93mm stroke with a lower redline... the C30A has a stock 90mm bore and 78mm stroke at 8200 redline... and a stroked (e.g. SOS 3.5L) is at 93mm x 86mm is theoritically at the same redline... I'm just wondering how much stress can these stroked NSX motors take or are they still within a safe threshold.

 

[A.S. Motorsport]

Great thread.

I'm curious about the upper sensible limit of the stroked C30As and C32Bs running around.

If the J series has a 89mm bore and 93mm stroke with a lower redline... the C30A has a stock 90mm bore and 78mm stroke at 8200 redline... and a stroked (e.g. SOS 3.5L) is at 93mm x 86mm is theoritically at the same redline... I'm just wondering how much stress can these stroked NSX motors take or are they still within a safe threshold.

Ohh this such a interesting topic!

Anyway max displacement for a DOHC C engine is 3.9 or that at least is the current record, i'm fairly sure you can run 4L your crank would need to have a long throw though.
Any one wanting BIG displacement must look into modifying a C35A tall deck RL engine to work with NSX head's no small project! as this would require a fair bit of custom machining, in terms of ports and timing belts.

You could then go towards 4.3L maybe bigger depending on crank clearance. whether that's useful is a whole different story.

The optimum angle for a V6 is '60 degree or 180 but that's a Flat/Boxer engine aka 911/Subaru H6.
The '90s in our cars are not optimum there pulses are rough and that can be heard in the great exhaust sound, that's why the tall deck C35A uses a balance shaft to make it silky smooth.

I speculate that the '90 angle was chosen by Honda to give a low clearance engine to aid weight distribution but also largely so they have a easy platform to go V8 if they ever sought fit. (the need was there by the mid ninety's they chose not to listen! bad call.....)
1995 Accord Coupe V6 was a emergency stop gap solution, retrofitting a old '80s C27A into the accord, that did require some modifications due to width of a '90 degree V but it lucky for them that width meant they could run a conventional hood, which would have been out of the question where the to have used a '60 degree block, even so i recall the fender and hood line to be taller so it would clear the upper part of the intake manifold.

The new NSX wil highly likely run a DOHC DI version of a J35 engine.
Honda can make undersquare engines rev like over square engines this in itself is testimony to there engineering prowess.
For example a B-Series is very undersqaure yet revs like a oversquare engine.

If you calculate the forces and piston speed on a little Type-R you will see that the physics behind that rotating assembly are quite large certainly compared to a NSX.

 

[JD Cross]

Ohh this such a interesting topic!

The new NSX wil highly likely run a DOHC DI version of a J35 engine.
Honda can make undersquare engines rev like over square engines this in itself is testimony to there engineering prowess.
For example a B-Series is very undersqaure yet revs like a oversquare engine.

If you calculate the forces and piston speed on a little Type-R you will see that the physics behind that rotating assembly are quite large certainly compared to a NSX.

Adnan

I looked up some of the Honda 4 cylinder engines.
The stroke is what determines piston speed.
A B16 had a 77 mm stroke and redline of 8200 rpm.
A B20Z had a stroke of 89 mm and a redline of 6800.
Both these engines have a piston speed of 21 - 21.5 meters/sec at these redlines and is about the same as the 78 mm stroke C30 series V6 NSX engines

Is this the piston speed maximum that Honda likes for it's street engines regardless of cylinders?

You say the B series is undersquare but revs like oversquare.
The B20Z is undersquare (84 mm bore) but the factory redline is less than the shorter stroke over square Honda engines.
Could you be more specific about your B series rpm data ?

Jim

 

[L_RAO]

Here are some comments from my engine builder:

"The 'aftermarket standard' redline for stock bottom end B18C motors is 9,200 with an 87.2 mm stroke (5,262 ft/min), and B16's regularly see 10,000 with a 77.4 mm stroke (5,080 ft/min). The valvetrain in those engines doesn't have any problem with that kind of rpm at all. The F20C at 9,000 rpm with an 84 mm stroke is at 4,960 ft/min and that's the stock Honda redline. The F20C is the only one of them that has forged pistons from the factory, but since the B-series bore is only 81 mm those cast pistons are substantially lighter than the 87 mm pistons in the F20C, hence the loading on the pistons and rods is less as well. At high rpm grams turn into tons! C30 engines have really beefy Titanium rods and forged pistons, so why are they running it at only 4,000 ft/min piston speed? Hell if I know. I limit my endurance engines to 5,400 ft/min but I'm using much stronger rods than Honda does. There are guys drag racing K-series engines that routinely exceed 6,800 ft/min!"

The bore-stroke is on an NSX motor (90 x 78), and it'd still be totally reliable at 9,700 RPM. Its no small wonder they last so long, using Honda's redline they never go beyond 4,000 ft/min piston speed. That's just babying that engine."

 

[A.S. Motorsport]

Adnan

I looked up some of the Honda 4 cylinder engines.
The stroke is what determines piston speed.
A B16 had a 77 mm stroke and redline of 8200 rpm.
A B20Z had a stroke of 89 mm and a redline of 6800.
Both these engines have a piston speed of 21 - 21.5 meters/sec at these redlines and is about the same as the 78 mm stroke C30 series V6 NSX engines

Is this the piston speed maximum that Honda likes for it's street engines regardless of cylinders?

You say the B series is undersquare but revs like oversquare.
The B20Z is undersquare (84 mm bore) but the factory redline is less than the shorter stroke over square Honda engines.
Could you be more specific about your B series rpm data ?

Jim

Take a look at the B18C Type-R engine it's under square as well and it will rev like hell.
81mm bore with a 87.1 mm stroke

- - - Updated - - -

Here are some comments from my engine builder:

"The 'aftermarket standard' redline for stock bottom end B18C motors is 9,200 with an 87.2 mm stroke (5,262 ft/min), and B16's regularly see 10,000 with a 77.4 mm stroke (5,080 ft/min). The valvetrain in those engines doesn't have any problem with that kind of rpm at all. The F20C at 9,000 rpm with an 84 mm stroke is at 4,960 ft/min and that's the stock Honda redline. The F20C is the only one of them that has forged pistons from the factory, but since the B-series bore is only 81 mm those cast pistons are substantially lighter than the 87 mm pistons in the F20C, hence the loading on the pistons and rods is less as well. At high rpm grams turn into tons! C30 engines have really beefy Titanium rods and forged pistons, so why are they running it at only 4,000 ft/min pistonspeed? Hell if I know. I limit my endurance engines to 5,400 ft/min but I'm using much stronger rods than Honda does. There are guys drag racing K-series engines that routinely exceed 6,800 ft/min!"

The bore-stroke is on an NSX motor (90 x 78), and it'd still be totally reliable at 9,700 RPM. Its no small wonder they last so long, using Honda's redline they never go beyond 4,000 ft/min pistonspeed. That's just babying that engine."

My point exactly!

 

[JD Cross]

Now this is getting interesting.

The 95-00 JDM Honda Integra Type R DB8 has an 81 mm bore, 87.2 mm stroke and factory redline of 8600 rpm for a piston speed of 25 meters/sec.
Can we assume Honda is comfortable producing a factory engine with speeds in the 25 m/s range?
Is this because of the small and light 81 mm pistons?
As L_RAO states the C30 with a 78 mm stroke could rev to 9700 rpm and a piston speed of 25 m/s.

Is there a rpm restriction in the C30 due to the larger/heavier reciprocating parts?
This would put an 8000 rpm J35 in the 25 m/s range unless there is a similar weight issue with the 90 mm bore reciprocating parts.

What type of HP per liter do you think Honda can make today with direct injection and an 8000 rpm J35?

Jim

 

[A.S. Motorsport]

NSX engines aren't maxed out they are limited to then Japanese power cap of 276PS, that's why they weren't given equal length headers in '90.
And why NA2's have slightly to small throttle bodies.

Quick math (rough!)
F20C S2000 = 120HP/L on a old school setup
Add I-Vtec you win a few HP but get a much better torque curve

A direct injection J engine gains 10% power and a lot of economy.

120*1.1 = 132HP/L

Now this is not exactly scientific but the gain on the J engine was a economy tune done for the new 3.5 vs the old 3.5
Add a performance tune to that with higher compression and more RPM.

132 x 3.5 = 462HP now we are talking seriously quick. although emissions and boardroom conservatives will kick that back a notch maybe to 100-115 HP/L

 

[JD Cross]

If we think 115 hp/ltr. is doable then the new NSX with J35 engine would have about a 400 hp base.
The current J35Y3 makes 310 hp at 5800 rpm or 53 hp per 1000 rpm. While this is not scientific if we assume an 8000 rpm redline we could see over 400 hp which backs up your 115 hp per liter.
This would suggest that the new NSX with say 400 hp gasoline and 80-100 electric hp for short bursts that the peak horsepwer of 480-500 hp we hear about could be done without turbocharging.

However I think our FI experts would say why not just turbo the J35Y3 to about 500 hp and be done with it.
No electrics, lighter weight lower cost Hmmmmm

What are we missing?

Jim

 

[A.S. Motorsport]

When it comes out, i'll get my hands on one asap and start with intake en exhaust mods.
A turbo setup would be awesome but would require some R&D as the aftermarket isn't yet used to the direct injection system from Honda.

My idea? add new Civic Type-R 1.6 Turbo injectors if those on the X aren't good enough.
The new 1.6 Turbo engine is rumored to push 260HP, add a 2.4L accord block and your looking at potentially 390 HP < don't know the bore/stroke spec yet on the DI engines.

I'm also highly interested in retrofitting a long trow J37 Crank in to the new engine bumping it up to 3.6 if the new one runs 89mm bores.
That would have my preference anyway a NA tuned enlarged engine, ITB's will sound just awesome.

 

[JD Cross]

When it comes out, i'll get my hands on one asap and start with intake en exhaust mods.
A turbo setup would be awesome but would require some R&D as the aftermarket isn't yet used to the direct injection system from Honda.

Won't the new NSX be selling in Europe for say 120 K Euro.
If you plan to take one apart to play with then you have much more money than me
Not sure how many new NSX owners would be willing to experiment with their cars in the early days.

Why not just develop a turbo J35 engine that would bolt into an old NSX as a turn key package?
Much larger market no?

Meantime still wondering why Honda would go to the trouble and expense on a hybrid driveline
if a turbo J35 would make the same power.
Perhaps it's more to do with handling not power????

Jim

 

[A.S. Motorsport]

Won't the new NSX be selling in Europe for say 120 K Euro.
If you plan to take one apart to play with then you have much more money than me
Not sure how many new NSX owners would be willing to experiment with their cars in the early days.

Why not just develop a turbo J35 engine that would bolt into an old NSX as a turn key package?
Much larger market no?

Meantime still wondering why Honda would go to the trouble and expense on a hybrid driveline
if a turbo J35 would make the same power.
Perhaps it's more to do with handling not power????

Jim

Ohh there will be owners interested in modifying the car straight away.
Occasionally I get customers in with a parts list for a car they haven't even taken delivery off.
Intake and exhaust sales on the new M5 and M6 are going good too.

CTSC where sold to many new NSX customers back in the day and dealer fitted to a new car.

EDM pricing is interesting topic,
Right of the bat EU pricing should be 120-150k, dutch pricing about 170k due to taxes here.

BUT the car is a hybrid so gets huge tax cuts i'd not be surprised to see it go on sale for 100K after tax rebates
It's not about power with Honda it's pure marketing and brand image, taking the moral high ground is a easy sale.

 

[RYU]

By virtue of deduction and sort of backing into my original question.. a "stroked" C30 should be able to operate safely at the stock RPM ranges. That's pretty exciting.

With Intake and head mods.. that makes it even more of an interesting proposition.

 

[JD Cross]

By virtue of deduction and sort of backing into my original question.. a "stroked" C30 should be able to operate safely at the stock RPM ranges. That's pretty exciting.

With Intake and head mods.. that makes it even more of an interesting proposition.

RYU

Ignoring the extra mass of a 93 mm piston and rod and heavier crankshaft, for a stroked C30 3.5 L to maintain the same piston speed as a stock C30 the 3.5 would redline at 7450.
The piston speed at 8100 rpm on a 3.5 would be 23.3 m/s.
The 23.3 is lower than the 25 m/s in the JDM Honda Integra Type R DB8 4 cylinder engine so perhaps that's okay

What I don't know is whether the extra mass of the 93 mm reciprocating assembly in the 3.5 L would be problematic compared to the Type R 4 cylinder with an 81 mm bore.
As L_RAO quoted "At high rpm grams turn into tons".

Jim

 

[A.S. Motorsport]

You should also consider mechanical balance so bank angle, number of cylinders and firing order.

 

[JD Cross]

You should also consider mechanical balance so bank angle, number of cylinders and firing order.

Could you pinpoint why each of those items would effect rpm?