S55 High Performance Valve springs

CarBahn Autoworks · 09-19-2019, 12:35 PM

S55 S63 High Performance Valve springs

I have been building racing and high performance road car engines for over 40 years. I am concerned about the trend in high performance valve springs on the new S55 and S63 engine.
Companies are selling springs with very high spring rates that will rob power and dramatically increase valve train wear.

Theory:
The goal of a valve spring pressure is to make it as low as possible. This is because compressing a spring takes energy and robs potential power. In addition, more valve spring pressure increases valve train wear. We work very hard at running just enough valve spring pressure to keep the follower in contact with the camshaft but no more. If you increase the RPM you increase the valve spring just enough to manage the inertia from the increased RPM. The valve spring also needs enough seat pressure and the correct frequency not to bounce when the valve is closed. This is to avoid leaking trapped mass (the fuel air charge).
Boosted engine
With a boosted engine you will need a slight increase in pressure to push back against the boost pressure in the intake trying to hold the valve open. This amount of pressure added is much less than the pressure to control the inertia of the valve train.
The S55 valve spring pressure is lower than the S65 engine and very close to the S62 engine. BMW worked hard at reducing the mass of the valve train by going to a finger follower instead of a bucket or hydraulic lifter over the valve. This was done to reduce the valve train mass so they could provide extra pressure for the turbocharged engine without increasing the valve spring pressure. This improves long term durability of the valve train.

Conclusion:
If you double the boost pressure you do not need to double the spring pressure since only about 20% of the spring pressure is to control the boost pressure and 80% is to control the valve train mass. An additional 20% of valve spring pressure is all you need to run.
Evidence of this is an S63 engine we built that produced 1300 hp and 1300 lb/ft torque at the rear wheels with stock valve springs!

CarBahn solution:
We include high performance valve springs with our engine, however you can purchase the springs separately. Our springs increase valve spring pressure by 20%. We also keep the steel retainers for long term durability.

Price is $629 per set

bracer · 09-19-2019, 01:31 PM

At what boost pressure are we seeing that this becomes necessary?

If / When I need an engine you will be my 1st call.

jpy1980 · 09-19-2019, 01:46 PM

Wow! Is that really Steve Dinan?!

Hi Steve!

FriedPiston · 09-19-2019, 02:25 PM

Quote:

Originally Posted by jpy1980

Wow! Is that really Steve Dinan?!

Hi Steve!

The entire context was copy and pasted directly from their website, so I would have to say no.

CarBahn Autoworks would you guys mind sending me a quote on Carillo Rods and CP Pistons (parts only) for the S55?

CarBahn Autoworks · 09-19-2019, 03:00 PM

Quote:

Originally Posted by jpy1980

Wow! Is that really Steve Dinan?!

Hi Steve!

Well sort of, Steve Dinan provided the information for the website and asked me to post it here for you to see.

CarBahn Autoworks · 09-19-2019, 03:02 PM

Quote:

Originally Posted by nars3000

The entire context was copy and pasted directly from their website, so I would have to say no.

CarBahn Autoworks would you guys mind sending me a quote on Carillo Rods and CP Pistons (parts only) for the S55?

Yes, I will get you a quote.

chetrickerman · 09-19-2019, 03:31 PM

What is the actual seat pressure with these springs?

Are they stress relieved? Shot peened?

What boost pressure and rpm are they rated for?

CarBahn Autoworks · 09-19-2019, 03:55 PM

Quote:

Originally Posted by blackey

At what boost pressure are we seeing that this becomes necessary?

If / When I need an engine you will be my 1st call.

I am waiting on the information from engineering to correctly answer this question.

CarBahn Autoworks · 09-20-2019, 10:28 AM

Questions on S55 Valve Springs:

What is the actual seat pressure with these springs?
A: 72-75lbs

Are they stress relieved? Shot peened?
A: Yes

What boost pressure and rpm are they rated for?
A: 40-45psi, 8,500rpm

At what boost pressure are we seeing that this becomes necessary?
A: There is an increase in power when you run over 30psi, however we have produced 1300+hp on an stock S63 so they don't become necessary...They will gain you power over 30psi.

09-19-2019, 12:35 PM	#1
CarBahn Autoworks Private First Class 232 Rep 103 Posts Drives: Lots of BMWs coming and going Join Date: Feb 2018 Location: San Jose, CA iTrader: (0)	S55 High Performance Valve springs S55 S63 High Performance Valve springs I have been building racing and high performance road car engines for over 40 years. I am concerned about the trend in high performance valve springs on the new S55 and S63 engine. Companies are selling springs with very high spring rates that will rob power and dramatically increase valve train wear. Theory: The goal of a valve spring pressure is to make it as low as possible. This is because compressing a spring takes energy and robs potential power. In addition, more valve spring pressure increases valve train wear. We work very hard at running just enough valve spring pressure to keep the follower in contact with the camshaft but no more. If you increase the RPM you increase the valve spring just enough to manage the inertia from the increased RPM. The valve spring also needs enough seat pressure and the correct frequency not to bounce when the valve is closed. This is to avoid leaking trapped mass (the fuel air charge). Boosted engine With a boosted engine you will need a slight increase in pressure to push back against the boost pressure in the intake trying to hold the valve open. This amount of pressure added is much less than the pressure to control the inertia of the valve train. The S55 valve spring pressure is lower than the S65 engine and very close to the S62 engine. BMW worked hard at reducing the mass of the valve train by going to a finger follower instead of a bucket or hydraulic lifter over the valve. This was done to reduce the valve train mass so they could provide extra pressure for the turbocharged engine without increasing the valve spring pressure. This improves long term durability of the valve train. Conclusion: If you double the boost pressure you do not need to double the spring pressure since only about 20% of the spring pressure is to control the boost pressure and 80% is to control the valve train mass. An additional 20% of valve spring pressure is all you need to run. Evidence of this is an S63 engine we built that produced 1300 hp and 1300 lb/ft torque at the rear wheels with stock valve springs! CarBahn solution: We include high performance valve springs with our engine, however you can purchase the springs separately. Our springs increase valve spring pressure by 20%. We also keep the steel retainers for long term durability. Price is $629 per set Attached Images Last edited by CarBahn Autoworks; 09-19-2019 at 02:16 PM.. Reason: additional info
	Appreciate 1 FriedPiston2006.50 Tweet

09-19-2019, 01:31 PM	#2
bracer Mr Bill 297 Rep 544 Posts Drives: GLC63 Join Date: Sep 2013 Location: Aliso Viejo iTrader: (1)	At what boost pressure are we seeing that this becomes necessary? If / When I need an engine you will be my 1st call. __________________ 2018 GLC63 2016 Miata 2020 X3M (sold) Turbo Miata Racecar (sold) 1995, 2009, 2015 M3 (sold)
	Appreciate 0

09-19-2019, 01:46 PM	#3
jpy1980 Lieutenant Colonel 1593 Rep 1,971 Posts Drives: 2015 BMW M3 -Smurfy Blue Vinyl Join Date: Sep 2018 Location: Los Angeles iTrader: (3)	Wow! Is that really Steve Dinan?! Hi Steve!
	Appreciate 0

09-20-2019, 10:28 AM	#9
CarBahn Autoworks Private First Class 232 Rep 103 Posts Drives: Lots of BMWs coming and going Join Date: Feb 2018 Location: San Jose, CA iTrader: (0)	Questions on S55 Valve Springs: What is the actual seat pressure with these springs? A: 72-75lbs Are they stress relieved? Shot peened? A: Yes What boost pressure and rpm are they rated for? A: 40-45psi, 8,500rpm At what boost pressure are we seeing that this becomes necessary? A: There is an increase in power when you run over 30psi, however we have produced 1300+hp on an stock S63 so they don't become necessary...They will gain you power over 30psi.
	Appreciate 0