Engine and Transmission Tech

tips, technology, tools and techniques related to vehicle driveline components

Go to Thread: PreviousNext
Go to: Forum ListMessage ListNew TopicLog In


quietone
Larry Mimbs
Tennille, Ga.
(93 posts)

Registered:
07/13/2013 04:22PM

Main British Car:


RV8 valves
Posted by: quietone
Date: June 25, 2014 07:05PM

Does anyone have any experience with stock valves at extreme (6500-7000) rpm? Curios about the strength of the necked-down valve stems.


roverman
Art Gertz
Winchester, CA.
(3188 posts)

Registered:
04/24/2009 11:02AM

Main British Car:
74' Jensen Healy, 79 Huff. GT 1, 74 MGB Lotus 907,2L

Re: RV8 valves
Posted by: roverman
Date: June 25, 2014 07:33PM

Why would you ? Stock valve sizes will likey flow/power peak, below 6k ?


quietone
Larry Mimbs
Tennille, Ga.
(93 posts)

Registered:
07/13/2013 04:22PM

Main British Car:


Re: RV8 valves
Posted by: quietone
Date: June 26, 2014 06:09PM

Actually, Art, I am using larger valves from an older 225 Buick. They are the largest valves that will fit in the heads without installing larger seats. They are also about maximum size for the ports with reasonable porting done. The stems are necked down and use the same keepers. Therefore the question. Thanks.


MGBV8
Carl Floyd
Kingsport, TN
(4511 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB Buick 215

authors avatar
Re: RV8 valves
Posted by: MGBV8
Date: June 26, 2014 06:55PM

Nice. Some flowbench data would be good. ;)


quietone
Larry Mimbs
Tennille, Ga.
(93 posts)

Registered:
07/13/2013 04:22PM

Main British Car:


Re: RV8 valves
Posted by: quietone
Date: June 29, 2014 08:18AM

The question about rpm is critical to the engine I am building at the moment. There are, unfortunately, a number of things to be determined that depend on the rpm available. I have generally, within reason, selected components that are capable of operating at reasonably high rpm. My target horsepower is 425. Somewhere, rattling around in my head, is the idea that I will probably need around 6500 rpm limit. Now I'm an old guy and a fairly conservative driver, but when I push the pedal down, I like to see results. Hopefully, the pair of KKK turbos will give me a fat torque curve. I have spoken to Dan Jones about designing a roller cam to do the job.

I would rather not be looking for custom valves. Thanks.


roverman
Art Gertz
Winchester, CA.
(3188 posts)

Registered:
04/24/2009 11:02AM

Main British Car:
74' Jensen Healy, 79 Huff. GT 1, 74 MGB Lotus 907,2L

Re: RV8 valves
Posted by: roverman
Date: June 30, 2014 10:56AM

425 "actual" hp., is a LOT, for an RV8 ! Say perhaps 20+ lbs, manifold pressure ? Care to describe your build plan ? Good Luck, roverman.


quietone
Larry Mimbs
Tennille, Ga.
(93 posts)

Registered:
07/13/2013 04:22PM

Main British Car:


Re: RV8 valves
Posted by: quietone
Date: July 01, 2014 05:48PM

The turbos are from a 996 that is 3.6l and makes 420 "actual" horsepower at 6000 rpm and 10.6 lb. boost. They have 4-valve heads, but I will be able to run a more aggressive camshaft. I also want a little more rpm to work with. Hence the original question. How many rpm will new stock valves handle?



roverman
Art Gertz
Winchester, CA.
(3188 posts)

Registered:
04/24/2009 11:02AM

Main British Car:
74' Jensen Healy, 79 Huff. GT 1, 74 MGB Lotus 907,2L

Re: RV8 valves
Posted by: roverman
Date: July 01, 2014 06:31PM

IMHO, I would know what the RV8 heads flow, from .05" - max. lift. Buick Grand National/turbo valves, "may" have better suited metalurgy. I still suspect, with reworked RV8 heads, you will need close to 20 lbs. manifold boost. Understand, with ported TA heads, you would need much less boost to equal the output. You have a rotating assembly, that will sustain this-reliably ? Good Luck, roverman.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6468 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: RV8 valves
Posted by: BlownMGB-V8
Date: July 02, 2014 02:26AM

It's a balancing act, enough spring to not float the valves vs enough lift to fill the cylinders and then there's the life of the valvetrain to consider, etc, etc. I've gotten 7 grand with less than 120 lb seated pressure...

Jim


quietone
Larry Mimbs
Tennille, Ga.
(93 posts)

Registered:
07/13/2013 04:22PM

Main British Car:


Re: RV8 valves
Posted by: quietone
Date: July 02, 2014 04:42PM

Jim, what kind of valves were you using?


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6468 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: RV8 valves
Posted by: BlownMGB-V8
Date: July 02, 2014 06:25PM

Buick 215


quietone
Larry Mimbs
Tennille, Ga.
(93 posts)

Registered:
07/13/2013 04:22PM

Main British Car:


Re: RV8 valves
Posted by: quietone
Date: July 03, 2014 04:53PM

That's the answer that I have been looking for. Thanks!


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(6468 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: RV8 valves
Posted by: BlownMGB-V8
Date: July 03, 2014 05:33PM

No problem, hope it helps.

That was with CC's hottest SBB hydraulic which they don't offer anymore. The springs were the ones they sold with that cam. Back about 1985 or thereabouts.

Jim


Sorry, only registered users may post in this forum.