7K Hydraulics

I always understood that Hydraulics were only good to 6500rpm. Yet the vette guys say the current z06 and zl1 redline at 7100. Is there something that chevy does that cannot be done on a ford SB?
 
My experience with Vette guys is they all think they can do things better!:) You can get any hyd lifter to work around that RPM level as long as you choose components & make mods to allow it, you also have to accept a few givens about oil pressure&temp in the process. Seriously though, when your using a hydraulic lifter in a pushrod motor as the 'rev limit' you will always be on the threshold of disaster or at least some power loss when the lifter pumps up, been there done that with clevelands at ~7000 for owners who are lazy or lacking in mechanical talent and dont want to check valve lash etc, the reality is that their mechanical awareness is also lacking and sooner or later they will run the motor over the lifter limit and damage it, at which time they also seem to absolve themselves of any responsibility.
 
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JohnC

Missing a few cylinders
Lifetime Supporter
Nearly all Ferrari's built since 2000 have been equipped with hydraulic tappets and their redlines exceed those mentioned. I think the only exception was the 456, which had shim over bucket solid lifters, and it went out of production in 2003.

My own '99 550 Maranello V12 has hydraulic lifters and redlines @ 7600, while the 360 Modena and F430 V8's also have hydraulics and redline @ 8500. And the latest V8 in Ferrari's stable, the 458 has hydraulic lifters and redlines @ 9000.
 
Not comparing apples to apples with the Ferrari examples though as the valves/springs/cam followers are smaller/lighter & with no rocker arm ratio/pushrod factors.
 

JohnC

Missing a few cylinders
Lifetime Supporter
You're right Jac Mac, but just an example to show that some hydraulic lifter technologies can do the higher RPM.

The Ferrari lifters are interesting, as at first glance they appear to be a standard, solid bucket type lifter, as used on most DOHC engines, but then as you press the button which contacts the top of the valve stem, it moves inward.
 
My experience with Vette guys is they all think they can do things better!:) You can get any hyd lifter to work around that RPM level as long as you choose components & make mods to allow it, you also have to accept a few givens about oil pressure&temp in the process. Seriously though, when your using a hydraulic lifter in a pushrod motor as the 'rev limit' you will always be on the threshold of disaster or at least some power loss when the lifter pumps up, been there done that with clevelands at ~7000 for owners who are lazy or lacking in mechanical talent and dont want to check valve lash etc, the reality is that their mechanical awareness is also lacking and sooner or later they will run the motor over the lifter limit and damage it, at which time they also seem to absolve themselves of any responsibility.

Except this is a new car with50k warranty from GM, so I wonder what it is that they do differently.

The Ferraris I understand thye have amuch lighter vlavetrain with a cam acting directly on the valve.

Which brings me to another question, Do lightwieght valves like titanium ones mean you can use less spring, are there lightweight pusrods, does this all lead to a virtuoius circle.

In otherwords what would be the ideal valvetrain setup for a SBF, say a motor able to rev comfprtably to 7.5K an d stay there.
 
Virtually every Japanese car seems to use cam followers of the type used in the Ferrari, so they are fairly common, Have a Subaru & 300zx here that will go north of 7000 easy if you push them, not much point though as they run out of air before that.

Lightweight stuff reqd to run continous @ 7500 with careful attention to springs to avoid surge. Rev kit to control the lifter without adding spring weight @ the valve.
 

Steve

Supporter
My 2cents if you want to rev to 7500 on a SBF:

1)Aluminum heads with titanium valves (lighter valve train).

2)Good quality shaft rockers for better durability, light weight, and more precise/consistent geometry. Stick with Jesel or T&D. They're tried and true. Others may be cheaper but, like so many things in life, you get what you pay for.

3)Work with a reputable cam manufacturer (Comp, Crower, Lunati etc) to select a cam/spring/lifter combo that will handle 7500 as well as work well together. It's more important that they be matched correctly than the actual part or manufacturer. This is how you will minimize resonance and how you will pick the appropriate setup for your heads/displacement.

4)Don't try to reinvent the wheel, use a combination that the cam manufacturer has had success with in the past. Sacrifice that last little bit of HP for durability.

5)What works on an OHC engine is not necessarily applicable to a push rod SBF, use a solid lifter roller cam.
 
The C6 Corvette Z06 revs to the low 7000 RPM range with a hydraulic roller cam but it uses titanium valves, lightweight steel rocker arms and lightweight beehive valve springs and retainers. They have had a significant number of valve failures.

The C5 Corvette Z06 also reved to about 6800 to 7000 RPM and used a hydraulic roller cam, steel valves, the lightweight rocker arms and lightweight beehive valve springs and retainers. Almost all of them that are tracked in open track events have had valve spring failures.

So yes as Jac Mac says, with the right lightweight components and cam profile a small block ford can be made to rev to the 7,000 to 7500 RPM range but the question again is for how long? Even the OEM's get that wrong sometimes.

Gord Zonailo
 
No room for a rev kit on the 8.2" block.
None of the current commercial offerings maybe,but there is enough room to do it on a one of basis by using specific lifter design & spot face underside of intake port area for springs, dont think that fits the OP's status though:), just depends on how much you want something.
There is a huge difference between being able to rev up to ~7500 thru the gears versus holding 7500 in high gear for a longer period of time on an oval track for example.
 
Jac Mac-
What were the limiting factors on the 289 MK I's? I seem to remember something about the front main being the weak link above 7,000 because of a harmonic in the crankshaft.
 
Ive read several articles to that effect also Doug, hard to pin it down to one single cause. As your probably aware the HiPo 289 had a much larger Damper plus an extra counterweight that sandwiched between crank gear & front journal. So Ford more or less must have acknowledged a problem. I 'think' there was an issue with balance at continous high RPM, articles from GW & other builders support that & GW went to some considerable efforts in Main Cap girdles that tied into the pan rail.
The nodular iron crank simply wont stand up to the abuse of a steel item and the 289 block regardless of whether its a HiPo or std item does not have a lot of metal in the main webs to prevent flexing.
On top of that you hear of teams/drivers that had excellent durability while others were forever in trouble....part of that could come down to the quality of the balance work, but some drivers 'knew' how to 'breath' the motor on long straightaways etc to avoid harmonic vibration buildup. When you read some of the comments from guys involved in the Shelby race teams about the 'quality' of some stuff provided by Ford it really makes you wonder if they were even interested in good race results. Little things like still running the factory pressed piston pin setup & big things like supplying factory ready-do not touch- tunnelport 302's that had a misfire on first start and found to be missing pushrods etc...makes you wonder...but then perhaps I shouldnt, I worked in a Ford dealership for three years, In that time I filled about six large foolscape folders with service bulletins of problems & cures,.... GM are/were no better, subscribed to a newsletter called chevy hotline for a few years- lots of 'production' faults to avoid there also, remember the first 'Tin' block my old Boss bought for his Camaro, lifter gallery oil drilling did not meet in middle of block & at that point was so low that it 'missed' the waisted area for oil on the lifter body, if not found at assy that would have resulted in a 'dry' pushrod/rocker/valvestem, but a quick burst with the diegrinder & it was all good.
 
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One other factor that is often mentioned is the firing order- 15426378, as opposed to the later 351 & 5.0 orders of 13726548, Fords data on that was to change the loading on the main bearings, BUT when you map out the two orders the early 289/302 one is the same as a small block chevy ( apart from the SBC having the cyls staggered in mirror image ) so that theory does not stack up either as chevy should have had similar problems,unless the ext balance is a major factor, ,1-5,2-6,&3-7 all fire one after the other on the front three rod journals.
 
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