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posted on July 3rd, 2014 at 01:36 AM
Hoover Mods - A Sideways Question
Hi Guys
I was reading about the Hoover mods the other day and got to pondering.
It seems that one of the key aims is to increase the volume of oil going to the right hand head / rocker etc.
This is achieved by increasing hte oil flow to the right hand side of the case / lifters by extending the oil passage to the 3 cam bearing web.
This modification is highly dependent on the squareness of the original oil way(which I understand is a bit dogy in new cases).
So in thinking this through, if you wanted to increase the oil flow to the right hand side without the risk associated with extening the oil way to
the no 3 cam bearing web, wouldnt it be easier to either:
1) Simply increase the size of the oil passage on the right hand side by say 0.5 mm. Would that not increase the oil flow to the lifters?
2) Rather than put a cross slit across the lifter so both portions of the lifter recess are active, simply machine the hump between the two chanels
down a bit so at all times there was poitive oil pressure to the push rods (and between lifters)
Just kicking it out there for discussion.
Newt
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posted on July 3rd, 2014 at 10:12 AM
To add to the thought, would machining the section between the recesses cause the lifter bore to wear as there would be less matterial to keep the
lifter travelling straight?
Newt
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modnrod
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posted on July 3rd, 2014 at 10:19 AM
I think Hoover's oil mod through the lifters is to improve the percentage of time the oil actually flows. I sorta remember that the oil flow is only
going through and up to the RH head 10% of the time or something, and sending oil through the cam web and then through the lifters constantly makes
that a 100% flow proposition when done (I think that's it anyway). Increasing the size of the stock passage wouldn't help the % open time.
Slotting the lifter galleries to allow constant flow is basically the same as slotting the lifters, except lifters can come out and be slotted easily,
and they cost $100, whereas the galleries would be a bugger to machine a slot, and the case costs bucketloads.
Other methods are used by OEM factories and tuners to supply more oil to the heads to reduce oil starvation at revs and galling through heat.
Suzuki's GSXR oiler motors (which are about the toughest thing ever) supply oil to a spraybar that shoots directly at the top of the
spring/retainer/rocker foot for each valve, although the Suzuki engineers themselves said that only the exhaust valves needed direct sprays to work,
the inlets were fine with splash. A lot of WRC motors have used this process too in the past, the V4 Yamaha Vmax motor, a few MX bikes, etc.
Most racers however actually want to REDUCE the flow of oil to the heads, thereby increasing the flow to bearings on the crank where mostly needed.
Ford Clevelands in particular need oil restrictors or the stock pump at high revs will drain the sump in one pass. Perhaps one way to go to get the
best out of the system would be to stop flow to both heads completely by blocking galleries with plugs, then supplying the piston undersides with
squirters (Toyota, Mitsi Evo, Porsche, whatever) to cool the barrels better than stock, and also use spraybars fitted with jets to regulate supply to
oil up the valvetrain and cool the heads.
Whether it's all worth it though on an engine that will already spin happily to 5000-6000 for over a 100K km is debatable however.
matberry
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posted on July 3rd, 2014 at 11:30 AM
Quote:
Originally
posted by modnrod
I think Hoover's oil mod through the lifters is to improve the percentage of time the oil actually flows. I sorta remember that the oil flow is only
going through and up to the RH head 10% of the time or something, and sending oil through the cam web and then through the lifters constantly makes
that a 100% flow proposition when done (I think that's it anyway). Increasing the size of the stock passage wouldn't help the % open time.
Slotting the lifter galleries to allow constant flow is basically the same as slotting the lifters, except lifters can come out and be slotted easily,
and they cost $100, whereas the galleries would be a bugger to machine a slot, and the case costs bucketloads.
Other methods are used by OEM factories and tuners to supply more oil to the heads to reduce oil starvation at revs and galling through heat.
Suzuki's GSXR oiler motors (which are about the toughest thing ever) supply oil to a spraybar that shoots directly at the top of the
spring/retainer/rocker foot for each valve, although the Suzuki engineers themselves said that only the exhaust valves needed direct sprays to work,
the inlets were fine with splash. A lot of WRC motors have used this process too in the past, the V4 Yamaha Vmax motor, a few MX bikes, etc.
Most racers however actually want to REDUCE the flow of oil to the heads, thereby increasing the flow to bearings on the crank where mostly needed.
Ford Clevelands in particular need oil restrictors or the stock pump at high revs will drain the sump in one pass. Perhaps one way to go to get the
best out of the system would be to stop flow to both heads completely by blocking galleries with plugs, then supplying the piston undersides with
squirters (Toyota, Mitsi Evo, Porsche, whatever) to cool the barrels better than stock, and also use spraybars fitted with jets to regulate supply to
oil up the valvetrain and cool the heads.
Whether it's all worth it though on an engine that will already spin happily to 5000-6000 for over a 100K km is debatable however.
Where's the like button???
Good post
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
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posted on July 3rd, 2014 at 07:41 PM
I've been thinking oil system mods a lot recently,I've been bouncing ideas off some"PROFESSIONAL BOGANS"I'm now about to throw the hoover mod
into the fray and see what happens?
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posted on July 3rd, 2014 at 08:24 PM
If I remember my physics correctly then if the area between the lifter grooves were machined to a smaller diameter then it would lower pressure to the
valvetrain and affect pressure backwards too.
IMO better oiling of the valve guides would add longevity to the engine as I've pulled apart a fair few engines that have only done around 100k and
the guides are quite badly worn in some cases but in all cases they are beyond the VW limit for guide wear by quite a bit.
madness is in the eye of the beholder
Newt
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posted on July 10th, 2014 at 10:37 PM
Pondering further.
Bob Hoover wanted to modify the oil feed from the rear cam bearing web.
If using this point was out (poorly drilled original tappet feed oil way), are there any negatives in doing the same mod from the front cam bearing
web (noted that you would also need to add a trench under the bearing).
Just musing.
Newt
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posted on July 11th, 2014 at 09:39 AM
Cancel that thought - there is no matterial under the cam journal to do this.
Newt
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