Posted by eg2 frank (firstname.lastname@example.org) on May 14, 1998 at 01:07:53:
Could you tell me more about your B16A motor? What kind of rod/pistons (CR). What kind of valve train components (cam, springs, valves)... How much power? Ever dragged it?
I have seen/heard quite a bit of B18C/B16A that revs to 9000 rpm and lives happy. (kind hard for me to believe Type-R B18C are breaking bottom ends... factory fuel cut are 8600 rpm). However, no cam I know makes power beyond 8500 rpm. Even huge Mugen Group-A cams peaks at about 8200 rpm, I suspect the cam gears wasn't used to its full potential in that application though. (this person shall remain anonymous).
Can you shed some lights on cam profile for high rpm (say 9500) power? Perhaps it's lift that these Honda motors aren't happy with. Even Group-A cams are no more than .600". Not sure on the duration. What do you know about this?
Also, Nitro mention you guys had added 5/8" deck height to a motor in
order to use longer rods and get better rod/stroke ratio. How much does
it cost to do that (for
a regular guy)? You can just welded it on top of the
cylinder sleeves?? Or was it major work requiring whole new taller sleeve/liners? Do you need to warm up the block
or anything like that? Where can I find a machine shop
that'll do this?
PS, one last thing, do you do offset wrist pin on your motors? i saw somebody talking about it and it interested me.
Posted by T.O.O. on May 14, 1998 at 21:05:04:
In Reply to: TOO: Q on your B16A and adding 5/8" deck height... posted by body on May 14, 1998 at 01:07:53:
The addition of the plate is primarily to allow us to achieve a 1.75-1
L/R ratio, which I, and numerous others, have found to be universally optimum.
The reason the factories don't use it is due to engine "package height".
Performing the process properly for the intended application is time consuming and, therefore, expensive. As we've been building components from welding rods for twenty some years now, we use some rather complex procedures.
First the block is etched slightly for cleanliness. The upper portions of the iron cylinder are bored out. The head plate (which is already profiled on the jacket side) is placed on top of the block. All surfaces to be welded are relieved so the weld will achieve maximum penetration. The two pieces are then heated to 400 degrees, and the welding begins while temperatures are held as constant as possible. The welding includes the exterior perimeter, and inside the OE bore size cylinder "holes" in the plate. So the bores of the plate are welded to the Honda parent aluminum cylinder exterior. The block is then placed in the oven to "normalize" the aluminum (both factory and the plate/ weld). Once this is complete we re-heat treat the block assembly to our specs. This process is an absolute necessity if future "movement" and strength is desired. The process is also very tramatic, and the amount of warpage is considerable, so we use four "master" location points, and remachine the entire block. The main bearing housing is one of the first areas, since we use this to bore on center each cylinder, removing slight amounts of material from both the plate and the original aluminum bores. The block is then gradually warmed to 200 degrees, and the "frozen" composite cylinders are shrunk into place. Composite doesn't necessarily mean what you may think. In this application it's a multi alloy / ceramic imbedded sleeve that gives the cylinder / piston some adeabatic and low friction qualities. All surfaces are remachined, all bolt holes are remachined and all threaded holes are either sleeved with steel threads or machined to a size we feel would be benificial to block integrety. The crank bore is finished honed, and the cylinders are diamond honed to spec. Typical piston to wall clearance for a blown Honda is 0.0018" using our multialloy pistons. The pistons are designed to provide the optimum combustion space with the combustion chamber in the head of choice. Although we rarely measure CR, it'll usually run from 11.5 to 16.5 for the Honda's, as the bores are so small, we don't need to make the final "space" as tiny as many other engines. Point is that the shape of the combustion space needs not be different regardless of application.
The rods are currently some of our own manufacture, and are machined from forgings we used for small block Chevy's. We have a vendor who is currently working on a mass produced selection of rods for the Honda's, and we're anxiously awaiting some pieces for testing. Before I forget, I no longer offset rist pins, and when we did, it wasn't to the same direction everyone else moved theirs. Our pins are tool steel and very light.
The cams we run are produced here. If you're in the business of building engines for competition or OE programs, it's absolutely necessary that you have your own cam manufacturing capabilities.
The "wildest" Honda grind we did some years back for a n/a engine had actual valve lift of .527/ .502, with actual durations of 234/ 232 degrees int. and exh. respectively. All valves are titanium or "lighter" materials. Our springs are made to spec. by Associated Spring, with the exception of the titanium units.
Our cams differ considerably from conventional units inorder to allow the combustion space to be proper, ie., elimination of valve reliefs,etc. All our cams stagger the intake valve opening, however, the lift is the same, and both close at the same time. Typical stagger is 10 degrees on innitial opening, so the acceleration rates are considerably different for each intake valve, and thus the differing weight materials. Spring pressures are determined by spin fixtures, and are the absolute minimum necessary to precent valve separation and seat bounce.
The cams for the blower engines have "lots" of lobe separation and little or no "conventional " overlap. Typical duration for a 1000 hp engine are in the 245 range for intake and 215 for exhaust. Lift never exceeds .500", it's simply not necessary, and the additional spring pressure required to control the valve would negate any potential power gain.
I might mention that the n/a cam specs were based on 116 degree lobe centers, and in an engine with 1175 cc. displacement (and correspondingly smaller valves) produced over 275 hp. with a usable rev range from 8500 to 14,500rpm.
Another subject quickly. If I don't provide an answer to a question, it's either because I've not sufficient time (like now) , the question is so far back that I don't catch it, or in many cases other board members have provided accurate answers.
Time to sleep...highest power...Tinker Bell is currently at 1100 and change now that the fuel curve is getting close. We're moving slowly as there are precious few block castings remaining, and the billet crank cost a lot in time. We will see more, rest assured.