Engine Cylinder Bores 1

[mart]

Project aims to examine the state of the art with respect to interanl honing of petrol/diesel engines.What is the ideal surface texture on the engine bore that will improve the engine performance, reduce oil consumption and lessen harmful emissions? Can anyone provide info on this, or point me to useful sites. Thanks.

 

[grego]

Mahle engine products in germany have very good engineering<br>
guidelines for honing cylinder bores.<br>
supply automotive industry with piston --liners etc.<br>
petrol -- major suppliers to the car racing users across<br>
the world.<br>
also major supplier to the diesel engine reco industries<br>
the company I work for is a large customer of Mahle products<br>
and I receive updates on engineering guidelines etc.

 

[Frederick]

Sunnen is the company to contact in the US. They supply honing products and machines to most of the racing industry. You can probably find them with a brief search, or contact our racing specialist by email at <A HREF="mailto:rgs@megsinet.net">rgs@megsinet.net</A>. He can give you a contact at Sunnen to talk to, and he can also tell you quite a bit about his experience.

 

[edkay]

Lisle Hones suggest approx. 280 grit stones to prepare a cylinder for standard rings and 450 grit for moly rings. I dont know if this is the type info you are looking for, but you may get more details from ring manufacturers.

 

[WGJ]

I was involved with some work on improving oil consumption of diesel engines a few years ago and one popular finish at the time was produced by a process called 'Plateau' honing. This, I hope I recall correctly, was where the bore was first honed with a relatively coarse stone and then a much finer stone, so that (in magnified cross section) the bore was like a mountain ragne with all the peaks flattened - hence 'plateau' honed. The hone head was also moved in synchronisation with its rotation to give a 45 degree cross-hatch pattern in the bore.
Another good finish for wear and oil consumption control was used in engines with cylinder liners. The liners were chrome plated in the bore before finishing to size by slurry honing. Under a microscope, the bores looked like an orange peel - many, many pits or dimples covered the surface of the bore. The slurry hone was done (I think) using aluminium honing sticks instead of carborundum. The bore was then flooded with a carborundum slurry which the al sticks rubbed into the chrome surface finish.
If you want detail, try contacting British companies GKN and Laystall.

 

[JEves]

WGJ and others-

I work for an engine manufacturer and we are currently undertaking a project where new piston rings and cylinder bore finishes are being tested. The ring manufacturer specifies a specific plateau hone finish where the Rpk, Rvk, Rk, and Mr2 values are specified. All information I have found relating to plateau hone finishing is vague, to say the least, where finish is achieved by running a coarse stone followed by a fine stone. I have found nothing which helps to understand how to achieve a specific “engineered” finish. Can anyone provide any insight as to how to achieve (or tips on where to start) the specific plateau hone results or are we left to the trial-and-error method?

 

[LyonsHeart]

All I know is that the surface mustnt be too bright, because the oil wouldnt be able to keep and lubricate the rings.
But on the other hand, shouldnt be a loss of compression.
Is difficult to measure it.
But it is made. Specially in Repair shops and rectifiers.

 

[franzh]

One interesting twist to the honing issue:

Several years ago, I was a reviewing faculty on a grad student program, and was presented with a fascinating dissertation on cylinder honing.

The cylinders were ceramic, of which were effectively impossible to use a conventional hone to obtain any discernable pattern. The cylinders had a slight texture to them, sort of like 2000 grit sandpaper. To remove the last bit of grit and prepare them for rings, a polymer slug coated with diamond dust was used in a cylinder hone fashion which polished the cylinder to the perfect finish. This was in the early 1980's, on a diesel engine, destined for adiabatic operation. I was later presented with some engine figures which were VERY impressive. I lost track of the student (now a Ph.D with some engine company somewhere.) I think the engine was a Cat.

 

[WGJ]

Sorry - this isn't directly related - JEves are you the same JEves that used to work at Dunton?

 

[JEves]

WGJ-

No, Never worked at Dunton...must be another JEves out there.

 

We At Vardhan Works Pvt.ltd.-Pune- India have manufactured an inspection instrument Microscope SPM4
by which it is possible to view on line as well as instantly photograph honing pattern
& measure the cross hatch angle on your PC.
Most of the liner companies in India have started using it.If you are interested Please
contact vwpl@pn2.vsnl.net.in

 

[pearlite]

Pearlite Liners Ltd.,India - being one of the largest cylinder manufacturers in the country have made considerable achievements particularly in the aspects like development of Plateau Honing. Should you need any further information about the product range, you may approach them on their mail id: pearlite@sancharnet.in

 

[MaxRaceSoftware]

A very good torque-plate hone job on a racing
block should only have between 2.5 -to- 4.5 CFM
Blowby readings, under full-load dyno test,
past about 6.0 CFM Blowby,
horsepower/torque losses will increase

i know shops like to bore the block with
torque plates..then when it comes time to hone
...the block's bores are already round..
this cuts down costs of honing stones
and makes honing quicker and more profit !!

You learn nothing , or don't learn enough
about a block if you bore the block 1st with
a torque-plate......after its bored then bolt
the torque plates on.....then check the
bore roundness, if the block's bores are
distorted more than .001&quot; to .0015&quot;,
then don't hone that block to a mirror 600 grit
finish ...no matter how good you hone that block,
its going to keep moving around !!
If its distorted more than .0015&quot; to .002&quot; ,
then don't even hone it to a 400 grit finish,
keep it at 280 grit or under 400 grit, because
that block also probably won't stay round
and seal great under full load !
In other words..the LESSER the bore distortion
after you bolt on the torque plates...the
smoother the hone finish ,,,,
the greater the bore distortion after you
bolt on the plates, the rougher the hone grit !!

Also, you have to be extremely carefull
when trying to hone a block's bores to
400 -to- 600 grit finish or the new plateau
finishes...with these smoother finishes,..you want the
bores to &quot;reflect&quot; back shinny &quot;white-light&quot;
...and not shinny &quot;dark-light&quot; back at you as
you shine a drop-light at the bores !!
If the bores are smooth but they reflect back
a dark-shinny light..this means you a folded
the &quot;honing peaks&quot; over the &quot;valleys&quot; from too much pressure
or loaded stones...rather then cleanly cutting
the &quot;peaks-off&quot;....what will happen next, is
after you start the engine and the rings wear away
some of the bores , the trapped debis in the valleys
will be exposed, and some loss of quality ring seal
will result from scuffing !!!!

Larry Meaux (meauxrace2@aol.com)
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

 

[evelrod]

Larry, were your blowby readings from test runs on large displacement engines? The reason I ask is my last engine, a naturally asperated 1598cc Lotus twincam with a VE in excess of 100%, blowby was considerably less than your figures. Less than one cfm . I don't remember the specifics of that engine , I seem to have missplaced my book with all my spec sheets, but I remember the hp was calculated at 205 corrected. The rpm range of that engine was 5500 to 8500 if memory serves me. I know it is not practical to compare figures from one dyno to another or, indeed, from one operator to another. I just don't have a great deal of experience on the dyno, just with my own engines and what I have been able to learn by reading and watching (when they would let me).

On the question of hones, I use a torque plate with a head gasket and a 280 +/- grit initial pass with 400 finish pass. Deves rings in most cases (Cosworth in others) and usually between 50 and 100 hours of engine time between rebuilds. Even then the rings are still good , but showing wear. Bores appear as near new. I have considered using harder rings and smoother bore finish, but since the engine must come down anyway and, race engines often get little or no break-in, it would not be cost efficient. I have not done many street engines, so I cannot address wear problems there.

Again, I really enjoy your posts, thanks.



Rod

 

[MaxRaceSoftware]

Thanks Rod, for the compliments !!
Most of the engines i dyno are V8s from
305 cid to 620+ CID ( 500 Hp to 1230 Hp ranges)
Some of the 305 to 355 cid NHRA Super Stock and Comp Eliminator engines will have 2 to 4 CFM Blowby max .
You have to make sure valve covers and everything else
are &quot;tight&quot; or blowby readings will be false !(too-low)

Some of the very small rod ratio (under 1.45:1)
large CID engines will have 6 to 8 sometimes 10 CFM blowby
(540 cid to 620+ cid sizes) ...these engines will benefit the most from such as Moroso crankcase vacuum pumps pulling near 17 inches of vacuum or switching over to dry sump pans with one or more of the oil pump stages for engine vacuum
...sometimes as much as 25 HP can be gained at 17 inches of vacuum with these type large displacement , bad rod-ratio engines !

Blowby CFM readings can only be read if you dyno &quot;without&quot;
a vacuum pump or dry sump ....so on some engines we dyno without the vac-pump hooked up and check blowby thru a CFM meter ..then we hook up the vac-pump and check the Torque/HP differences for the remaining dyno tests

Larry Meaux (meauxrace2@aol.com)
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

 

[MaxRaceSoftware]

Trapped Engine Ve% = Total CFM - ( Blowby CFM + OverScavenge CFM ) Larry Meaux (meauxrace2@aol.com)
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

 

[sbc]

A lot has been covered here, and pretty well. Larry M.
is right, folded metal is baaad. Too much stone pressure
while rough OR finish honing will give you headaches later.
Pay attention to the matl. of the bore and the finish that
the boring process leaves, ie. how much matl. should you
leave for honing? Too much honing makes it hard to keep
the bore true. Idealy the cylinders should be and stay in a free state, if you're designing an engine try for this, it is why some engines have long studs which clamp the heads from the main brng. webs instead of the deck of the block. Tork plates & torking main caps are a must & I've seen guys bolt on the waterpump & bell housing etc... and pre-heat the whole block. Piston & ring selection is critical and is
going to be determined by what you intend to use the engine
for. A light weight assy. will not do well in a towing rig.
There are a zillion combinations out there but the piston
mfgs. (Weisco, Keith Black, Fed. Mogule ect...) will help
you to determine your best combo. & what is the best bore
finish for it. Be warry though I have been in some &quot;big Buck&quot; engine shops & seen some odd things. I've checked
bores from underneath after the heads & intake were torked
on & found that when the heads & intake were machined for
increased compression they didn't fit together well and
caused distortion in the bores. How far should you go for
a grocery getter? street machine? bracket racer? Just
remember Speed is Money, How Fast Do You Want To Go?

 

[MaxRaceSoftware]

. I've checked
bores from underneath after the heads & intake were torked
on & found that when the heads & intake were machined for
increased compression they didn't fit together well and
caused distortion in the bores. - sbc
-------------------------
i've done the same thing , checking bores from underneath.

i've had a &quot;homemade&quot; leakdown tester running on 175 psi
in a cylinder ..while i began tightening down the intake
manifold ..just to see what effects..and sometimes you could see 1.00 % percent more leakage ..and that wasn't necessarily a &quot;bad&quot;-fitting intake , but a combination of a thin block !!! When using angle-milled heads on
blocks with studs....if the headbolt holes weren't milled back straight/perpindicular..then body of the studs will sometimes interferrence-fit inside headbolt tube-holes
enough to cause cylinder bore distortion and blowby
along with headgasket failure on high comp ratio engines


Larry Meaux (meauxrace2@aol.com)
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

 

[BSteele]

JEves,

I'm interested in knowing what Rpk, Rvk, Rk and Mr2 values were specified by the piston ring manufacturer? Also, what size of bore, operating RPM and fuel type is this engine? I've found Ra to be a rather archaic way to specify the surface finish on a cylinder liner.

 

[dday5000]

We can help you determine the best surface finish with our Advance Technlogy Center at Micromatic Textron.

Contact John Goodman at 317-841-9443