3.1, 3100, 3500?? build options

[geoffinbc]

7000 RPM is realistic. But there is no reason to sacrifice that extra stroke to do it. You can spin the 3.31" crank to 8000RPM and be well within a safe piston speed. So reducing stroke will in no way allow your engine to spin faster.

If I was into this build and spending my dollars o custom pistons and rods then I would stroke the crank to the max the journals would allow. Spec a piston with solid ring lands with plenty of margin from the top of the piston to take the heat from the boost and then get a set of rods to zero deck the pistons.

As for the stock oiling system it would provide oil at any RPM the engine could handle. The priority main feed will keep all the bearings happy. The only thing I would consider is oil restricting pushrods and full roller rockers so I would not have to worry about excess oil up top.

[Mach 5]

just showing some links to what I feel are good websites for intake design for my personal build
I already know that there is a thread on intake design

http://horsepowercalculators.net/intake-manifold-design/intake-manifold-design

http://www.200sx.lv/forum/viewtopic.php?t=818

http://www.homemadeturbo.com/showthread.php?t=93372

[Mach 5]

7000 RPM is realistic. But there is no reason to sacrifice that extra stroke to do it. You can spin the 3.31" crank to 8000RPM and be well within a safe piston speed. So reducing stroke will in no way allow your engine to spin faster.

If I was into this build and spending my dollars o custom pistons and rods then I would stroke the crank to the max the journals would allow. Spec a piston with solid ring lands with plenty of margin from the top of the piston to take the heat from the boost and then get a set of rods to zero deck the pistons.

As for the stock oiling system it would provide oil at any RPM the engine could handle. The priority main feed will keep all the bearings happy. The only thing I would consider is oil restricting pushrods and full roller rockers so I would not have to worry about excess oil up top.

so you feel that this crank given 25psi more or less depending and 7500rpm should be ok with this 3500 crank..?? I am very concerned about this I do not want to over rev this motor either. I also would think that given that rpm I would have to start worrying about the secondary harmonics starting to take play to which with a shorter stroke even if its only 1-2mm shorter will greatly reduce the chance of this being an issue. Ive been reading on issue with the rb motors having this problem at around 8000rpm with bolts coming loose and bearing failure more of an issue on the larger stroke motors.

I am very happy just throwing around ideas right now starting next month the build will actually start

[geoffinbc]

Yes with a stroke that will still be under 3.5" 7500RPM will not be an issue. Piston speed will be well within a safe limit. You should be more concerned about a light valvetrain that can take the RPM and not the rotating assembly. An inline 6 engine will never have the same harmonics as a V6. The 60 Degree V6 does have a secondary imbalance but it is very small.

[Jonpro03]

Yes with a stroke that will still be under 3.5" 7500RPM will not be an issue. Piston speed will be well within a safe limit. You should be more concerned about a light valvetrain that can take the RPM and not the rotating assembly. An inline 6 engine will never have the same harmonics as a V6. The 60 Degree V6 does have a secondary imbalance but it is very small.

Exactly the concern I had. I don't know if a steet built pushrod valvetrain is capable of 7500rpms.

[Mach 5]

I would say 7k would be the max and I would be happy.

Does anyone have experience with the turbo race cam on here?? and the heads too??

[trotterlg]

I think to get to 7,500 you will probably need solid lifters, the standard roller lifters are heavy, so spring pressures will need to be high and lifter pumpup I am sure will be a problem. There is a good reason most high spinners are OHC engines. Larry

[ericjon262]

would it be possible to run a "rev kit" on a 60*? that'll keep the spring pressure down and keep the hydraulic lifters in check, it's be a one off piece, but you might be able to sell them...

http://www.airflowresearch.com/index.php?cPath=75

AFR claims a 100hp increase in power through better valvetrain control, and AFR isn't some fly by night company...

[Mach 5]

I thought they had lifter springs for sale on here.. Wouldnt that eliminate the issue?

[ericjon262]

IIRC, lifter springs go inside the lifter, a rev kit goes outside, around the pushrod, controlling the lifter. which allows the valvesprings to control the valves, not the whole valvetrain.

[Mach 5]

gotcha yeah it was late when i looked at the link. Now that I think of it its definitely do-able since the lifter bore are essentially 350 lifters. Im gonna talk to some people at my local speed shop -SK Speed- and see what they say.

oh and after thinking what abouit 3500 heads and lower intake along with the 3500 crank stroked .240 on a 3100?? Is this possible? This would make 208ci on the 3100 bore. or just leaving the stroke the same but still using the 3500 heads and intake and just grinding the rod journals down to accept sbc rods??

Thats a cool link Thanks!!
-Jarek

[geoffinbc]

Your still going to need solid lifters. A rev kit wont help hydraulic lifter pump up. Solid rollers along with good rocker and poly locks on the studs will virtually eliminate the need for adjustment.

[pocket-rocket]

Won't 3500 valves interfere with cylinder wall bores on a 3100, or am I mistaken?

[ericjon262]

Your still going to need solid lifters. A rev kit wont help hydraulic lifter pump up. Solid rollers along with good rocker and poly locks on the studs will virtually eliminate the need for adjustment.

I have seen dynographs of engines swapping between hyd and solid rollers, and the hyd rollers made better low and mid range torque, without sacrificing top end performance, I imagine running a rev kit with tighter lifter springs, and a little less seat pressure could get you to 7000 RPMs.

[geoffinbc]

Uhhhh... Can I see those dyno graphs? Because I call bullshit. Unless the test was done with the exact same cam then it is possible. You cannot compare hydraulic to solid on the same exact cam because the lash required by the solid lifter will greatly reduce duration and max lift. A solid roller cam is capable of TONS more velocity than a hydraulic one so it is possible to extract much more torque and RPM out of the engine.