Max viable RPM for Flat-tappet Hydraulic valvetrain?
09-05-2003, 12:52 PM
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Max viable RPM for Flat-tappet Hydraulic valvetrain?
I am thinking (Yes I know watch out for smoke 'n sparks :jester ).
I am putting on a set of ported Dport heads and an LPE 213 cam in the winter probably. I should see 5800rpms, maybe even 6000rpms with this setup with roller tipped rockers.
IS this ok for a Hydraulic lifters, or do I have to step up to roller?
The reason I don't want to convert to Roller, as it is an '85 block and I would need a roller conversion, whic is very expensive. (Trying to do this cheap as possible).
[Modified by MrNuke, 12:52 PM 9/5/2003]
I am putting on a set of ported Dport heads and an LPE 213 cam in the winter probably. I should see 5800rpms, maybe even 6000rpms with this setup with roller tipped rockers.
IS this ok for a Hydraulic lifters, or do I have to step up to roller?
The reason I don't want to convert to Roller, as it is an '85 block and I would need a roller conversion, whic is very expensive. (Trying to do this cheap as possible).
[Modified by MrNuke, 12:52 PM 9/5/2003]
09-05-2003, 02:28 PM
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Re: Max viable RPM for Flat-tappet Hydraulic valvetrain? (MrNuke)
I don't think RPM is the issue with a flat tappet cam so much as lifter failure and max cam lift.
The lifters should be able to handle the RPM and you can increase the apparent cam intensity by going up to 1.6:1 or even 1.7:1 RRs. This way you can increase valve ramp rate with the shallower profile of a flat tappet cam without the expense of converting to a roller cam.
BTW, if you are going to 6k rpm I assume you are using Ti retainers to minimize the chance of valve float. If the D-ported Al heads came with stock valves installed you should also toss those tin oil shedders from atop the springs to lighten the valve train. If you don't already have the roller tip rockers consider a set of ProMagnum full RRs. They will reduce valve train rotating mass and reduce friction.
For best results pocket port those heads and go with 2.00"/1.56" quality valves. Worked heads is worth another 25chp over the stock units.
You should get some realy nice gains from doing heads & cam.
The lifters should be able to handle the RPM and you can increase the apparent cam intensity by going up to 1.6:1 or even 1.7:1 RRs. This way you can increase valve ramp rate with the shallower profile of a flat tappet cam without the expense of converting to a roller cam.
BTW, if you are going to 6k rpm I assume you are using Ti retainers to minimize the chance of valve float. If the D-ported Al heads came with stock valves installed you should also toss those tin oil shedders from atop the springs to lighten the valve train. If you don't already have the roller tip rockers consider a set of ProMagnum full RRs. They will reduce valve train rotating mass and reduce friction.
For best results pocket port those heads and go with 2.00"/1.56" quality valves. Worked heads is worth another 25chp over the stock units.
You should get some realy nice gains from doing heads & cam.
09-05-2003, 02:28 PM
#3
Burning Brakes
Re: Max viable RPM for Flat-tappet Hydraulic valvetrain? (MrNuke)
It's not a problem as long as you have enough valve spring pressure to
keep from floating the valves. If the valves float, the lifter can then
"pump up", which will then not allow the valve to close completely, and,
well you get the picture.
I'm running a hydraulic flat tappet in my 85 right now and I'm turning it
6500rpm without any problems.
Edit - I should also add that I'm running light weight valves (hollow stem
intakes) and titanium retainers, and Comp Cams pro magnum rockers.
Dan
[Modified by danno85, 1:31 PM 9/5/2003]
keep from floating the valves. If the valves float, the lifter can then
"pump up", which will then not allow the valve to close completely, and,
well you get the picture.
I'm running a hydraulic flat tappet in my 85 right now and I'm turning it
6500rpm without any problems.
Edit - I should also add that I'm running light weight valves (hollow stem
intakes) and titanium retainers, and Comp Cams pro magnum rockers.
Dan
[Modified by danno85, 1:31 PM 9/5/2003]
09-05-2003, 04:02 PM
#4
Melting Slicks
Re: Max viable RPM for Flat-tappet Hydraulic valvetrain? (MrNuke)
I am putting on a set of ported Dport heads and an LPE 213 cam in the winter probably. (Trying to do this cheap as possible).
[Modified by NUckINg FuTS, 3:03 PM 9/5/2003]
