Gerg_R31

Ive done a few RB25/RB26/RB28/RB30/RD30/RB32 local and interstate machine jobs at my work if your willing to ship interstate

thought you went to castle hill exhaust (oh and im trying to find someone close to sea level as possible as you know my car doesnt have an altitude adjuster ) next week ill start calling up the tuners that i have in mind, will keep everyone updated

The following is intended to help some forum memebers with a better knowledge of the engine internals, after market parts, different materials, some machining processes, formulas and the "why is that done" this wont cover everything (based on the RB series but similar principals can be used on other motors) ************************************************************************************ Under standing how it works A internal combustion engine works on a 4 stroke or a 4 cycle rotation, intake (piston moves down air & fuel enter via Intake valve/s) compression (piston moves up compressing the cylinder) ignition (piston goes down as spark plug ignites the air fuel mixture) exhaust (hot exhaust waste is pushed out the exhaust valve) Or in short, suck squeeze bang blow ************************************************************************************ Choosing the right parts When modifying any motor the first thing you need to ask yourself is what is the purpose of the car? Why should you ask yourself this? Because all modifications will have benifits and losses. For example a factory car is designed for the lower rpm range and run out of steam in the higher revs, big turbos big cams will highly benifit in the higher revs but sacrificing power in the lower revs The general thing is to choose where your most likely going to spend the most time in a rpm range for your purpose (based on a twin cam rb30) street car 1000rpm-3500rpm street car / enthusiast track days 2000rpm - 6000 rpm street car / competitive track days 3000rpm - 7000rpm dedicated track car 3000rpm - 8000rpm + Choosing all the parts that will work with in that rev range will give a more benificial result in that rev range ************************************************************************************ Compression Ratios Compression ratios have more involved then what is stated on a piston box. i.e customer: "can you organise me some pistons with a comp ratio of 8.5:1?" "what head cc's head gasket you got?" custmer "oh no i dont want any head work done" and a few weeks later came back going off saying we ordered the wrong pistons, blah blah his mechanic found it was 9:1 blah blah" why was it higher? because he got a thinner head gasket, With that example out of the way, the following should give a bit more information for helping with ordering the right parts and having a job done right the first time. There are 2 types of compression ratios. Static and Dynamic Static Compression Ratio of an engine is the ratio of the cylinder volume compared to the combustion chamber volume where the swept volume of the cylinder, with the piston at BDC (Bottom Dead Centre) pushing via the crank stroke, into the closed combustion volume when the piston is at TDC (Top Dead Centre) Or in simple terms, for example 8.5:1, a piston at its lowest point can sqeeze the volume of air and fuel mixtures above it 8.5 times to make it fit into the volume above the piston when it is at its highest point (formula below) Static Compression Ratio Formula (metric units) Swept Volume Bore x Bore = Answer1 Answer1 ÷ 4 = Answer2 Answer2 x π (3.142) x stroke = Answer3 Answer3 ÷ 1000 = Swept Volume ( SV ) Compression Volume Head CC Piston dome/ dish volume Deck height (piston below the deck) Bore x Bore = Answer1 Answer1 ÷ 4 = Answer2 Answer2 x π (3.142) x block deck to piston crown measurement = Answer3 Answer3 ÷ 1000 = deck height volume Deck height (piston above the deck) piston measurement above top ring land x piston measurement above top ring land = Answer1 Answer1 ÷ 4 = Answer2 Answer2 x π (3.142) x block deck to piston crown measurement = Answer3 Answer3 ÷ 1000 = deck height volume Gasket Gasket Bore x Gasket Bore = Answer1 Answer1 ÷ 4 = Answer2 Answer2 x π (3.142) x Gasket thickness = Answer3 Answer3 ÷ 1000 = Gasket volume The Maths Head CC + gasket Volume + Piston dish Volume(- Piston dome volume ) + deck height (-if piston is above the deck)= CV SV + CV + Answer Answer ÷ CV = Compression ratio ************************************************************************************ Dynamic Compression Ratio, this is a bit more complex and uses the position of the piston when the intake valve is closing ABDC (After Bottom Dead Center) rather than the crank stroke to determine the swept volume of that cylinder For example a RB30DE motor with a static 10.5:1 and 10.8mm lift cams with 280° of duration (seat to seat) where the intake valve closes at 60° ABDC will rob 19% of the stroke making the rb30's 85mm stroke equivalent to a 68mm stroke and turning the 10.5:1 into a 8.7:1 The formula/ how to Measure how far the piston is down the bore just after the intake valve has closed, this to TDC is your Dynamic Stroke Repeat the same formula used to acheive the satic compression ratio but replace the engine stroke in the swept volume section with this measurement ************************************************************************************ Componant Materials/ info OEM (Original Engine Manufacturer) manufactured parts were quite often only desgined for the general basic driving and not expected to see past a certain rev or power range, or high stress like that of track days. Many OEM parts are still quite strong and can and will keep pushing past their expected limitations where others do not Alot of parts manufactured these days have improved their quality and consistancy, which has eliminated most of the old school "blue printing" as it has already been acheived through these high quality standards and more accurate machining, tools and machines for a machinist to machine things with spot on accuracy. for example cam followers in the older motors once had to be individually machined to match the curvature of the varying cam lones, but with the standards of today, the cam followers will generally have a consistant 0.002" to a 0.004" radius and are able to be mixed around without causing any issues (unless it is a solid shim set up which it is best to keep in order unless you plan to re shim it, or re machine to correct the clearances) Pistons If your measure a piston from top to bottom at room temperature the measurements will vary a fair bit, but at the engines operating temperature adding thermal expansion piston material thicknesses, the piston will change and become exactly the same size from top to bottom. This has all been designed to do this intentionally by the manufacturers. Cast pistons are cheap to make and can endure a long life under the standard conditions designed and built by the OEM Forged pistons are desgined with a higher silicon content which gives more control over the thermal expansion rates of the forged steel molecules, which in turn provides a stronger material to with stand more pressure and to with stand, absorb and transfer more heat. Connecting Rods Connecting rods come in many different materials, shapes, rods bolts etc. Material; Many of the OEM stuff is quite strong and can with stand a fair bit of high level stress, but consistant high RPM (6000+) will fatigue on the con rods material on a molecular level, where the rods will start to stretch after 6000rpm and go back to normal once below 6000rpm. Though after some time, the consistantly stretched rod will increase in length and form weak points where it can crack, split or snap. Below is how much the rods will stretch factory cast 0.0012" @ 6000 rpm steel 0.006" @ 6000 rpm billet 0.002" @ 6000 rpm alloy 0.020" @ 6000 rpm and times how much the material stretches per 1500rpm after 6000rpm Design; The rods design will help with strength from additional cylinder pressures and engine torque, factory I beam is the weakest, then H beam, and I beam being the strongest Rod bolts these things are what is holding the rods onto the crank, the torquier the motor the better quality the bolts should be for extra security. between the bolt head and the thread is usually a pattern that is designed to press and hold itself into the rod which will minimise its movements. Then the higher torque settings secure the rods onto the crankshaft. Bolts/ studs with torque settings Anything where there is something that will increase the torque settings from the OEM settings will most likely oval any bores, or tunnels, always best to measure with a bore guage or an inside micrometer for roundness, correct with honing, boring, or torque plate honing Heads Gaskets head gaskets are to keep the combustion chamber sealed, and prevent oil and water mixing / entering the cylinder Composite; this type of gasket is your every day head gasket. They usually dont vary in thicknesses. It needs a flat but not too smooth surface (or still shows signs of grinding marks) to seal properly. During temperatures above operating temperature heads will distort which can seperate the materials causing the head gasket to leak Metal; Or Multi Layer Steel gasket, this needs a smooth finish on both the block and the head with about a 7ra finish (smoothness rating) these come in many different thicknesses which will help to keep the compression ratio where it needs to be between machining. These aid with a better seal and during temperatures above operating temperature the gasket will stay intact and not seperate like the composite O-ring & Copper this is where the head and block is machined and an o ring is fitted to both to seal the cylinder. A copper head gaskets then seals around the o rings and the rest of the oil and water jackets Valves & Guides OEM steel valves are good for street aplications, and with the exhaust valve consistantly glowing red the wear factor is more expected. When the chamber conditions change it puts extra strain on the parts, more so the exhaust valve. Common failures that follow are exhaust guide bores becoming bigger, exhaust valve stems becoming smaller and the valve head starts to melt away, commonly know as a "burnt out valve" Stainless steel, nitrided (chemical process that hardenes materials) Inconel, Titanium valves are most common aftermarket valves with the metals more durable to harsher conditions. The after market materials also create an extra friction with cast guides so it is recommended to have bronze guide sleeves or bronze guides fitted to counter this Valves Springs Valve springs are there not only to help close the valves but to allow for sufficiant valve/ cam lift. to test a valve spring first you will need the installed height with the valve closed. At this point is where you geat your seat pressure, if your seat pressure is too low you will get valve float (where the valve will bounce off the seat instead of snapping shut) if its too high it will chew out the valve tip, cam followers, cam lobes. For max spring lift, installed height minus spring height at coil bind minus 0.080" thermal expansion & spring vibration clearance will equal your max lift. If the cam says more valve lift then your springs have then its time to invest in new springs. Using springs that dont have sufficiant lift to match the valve lift will create valve bounce. If you have a rocker then times the cam lift by the rocker ratio to get your valve lift Springs also come in various materials for better heat absoption tolerance and strength Camshafts Choosing the right camshaft is sometimes a bit of a mystery or a guessing game. The first thing you should ask yourself is the what is my car used for and pic a cam that is rated to give power with in that rev range. Going for the biggest lift with the biggest duration will be good for a dedicated drag or track car but not for a daily driver as it will rob you of all the low down power, this is called "over caming". Many cam grinders have tested each cam profile and have recorded when the cams work their best. You may find some cam grinders will have similar cam profiles to another, usually this is from someone desigining the cams testing them, then selling the master cam to their competition who may slightly alter the design to call it their own Turbo's are more happier with smaller lift medium to long duration. if you have a bigger stroke, i.e rb30 with rb26 cams then subtract about 500-1000rpm from the cam grinders rev range ************************************************************************************ Machining to some the machined surfaces dont appear to be that "important" and a home job is all thats needed, but it plays a large role if its done right the first time so things dont go boom or burn smoke etc. If you find yourself in this situation it is best to measure with bore guages, inside micrometres, normal micrometres. Vernie calipers arent accurate enough for a precision measuring tool ************************************************************************************ Bores Cylinder bores have a pattern known as the cross hatch. which is a series of 30° and 60° angled scratchs. These are designed to hold oil for lubricating the rings to prevent friction. Friction creates heats, heat creates premature wear, wear creates smoke. Glazed bores is where the bores look glassy and have no cross hatch pattern. Using the bottle brush hones you attatch to your drill, should only ever be used after you have measured the bores and there is no issues, other then a faded cross hatch, such as taper (smaller - bigger end to end), barreling (smaller top and bottom, bigger middle) hour glass (bigger top and bottom, smaller middle) or ovality (its an oval shape) Measure in 6 spots, top middle bottom front to back and side to side. For alloy bores or chrome moly piston rings or greater material a finer cross hatch is required, a plateu stone usually follows a hone to take any microscopic sharp edges off the cross hatch pattern ************************************************************************************ Crankshafts Measuring a crank should be done at to spots on each journal with a micrometer, north & south, east and west. This will not only determine if the crank is with in size or if its ovaled. If a crank has been ground, it doesn't hurt to recheck the size before assembly incase it is too small/ big or is ovalled. Also a commonly overlooked part is where the journal meets the counter weight webs should have a rounded edge, if its a sharp corner then that has not been ground right and the corner is where the crank will snap. Quite common for the gallery bungs to be drilled out to allow for a proper clean of all the oil galleries ************************************************************************************ Balancing Balancing is weight matching the rotational (rotating) and dynamic (up and down) componants. 1 gram of weight at 700rpm becomes 1kg of weight at 7000rpm, this extra weight will cause flex vibrations stress and can lead to early componant failure. Rods pistons rockers fall into the dynamic balancing section, to balance these you find the smallest weight and machine off in areas that wont weaken the componant to match the lightest. With cranks, flywheels and harmonic balancers they are all part of the rotating assembly (rotational), When balancing a crank and or flywheel you remove weight by drilling, linishing so the front to rear is the same as well as the rotational and "throw" of the crank, where in some cases an over balance is introduced to create extra throw(throw is the rotational force that keeps the crank spinning it the direction it was ment to turn). Most cranks are Internally balanced, meaning you can swap flywheels, pressure plates etc without having to re balance the whole lot Externally Balanced cranks are balanced by roughly equal weights, on both the harmonic balancer and the flywheel. to change one item you have to change both and have it re balanced. Sometimes mallory metal (a heavy dense metal) is needed to be machined to fit when you cant remove enough weight to counter the issue. When having to fit mallory metal it is best to put it in parralel to the journals as its less likely to come out then if its pressed or welded in via the drilled holes in the counter weights ************************************************************************************ Blue Printing Blue printing is making everything as identical as the next, i.e every rocker weighs the same, every piston and conrod weighs the same, every conrod is the same length, every clearance is the same, ever combuston chamber is the same. With everything running the same, there is an even balance of work being done in each cylinder componant, which creates less pre mature wear on the harder working parts cause there is none, and the benifit more efficancy and increase in power. Balancing is pretty much all that is left with blue printing these days as all parts have a better quality, back in the old days when the quality was not available you would for example get a box of pistons that said 0.005" piston to bore clearance and the each bore was machine to suit each individual piston. technology has improved, machines improved and blue printing is almost fased out ************************************************************************************ Porting Porting jobs vary depending on the aplication, for example a N/A motor with a stroker kit need bigger ports to help the motor breath. too big and it can make it harder to breath as its removed the velocity created by cylinder and atmospheric pressures, but bigger ports may help with turbo'd cars or dedicated race cars. Many port at home but the risk of each port varying in the flowing characteristics may make 1 cylinder work slightly harder then the other. The best thing to remeber with porting, is the manifold sides are wider for volume, higher for rev range. the bowl area is for atomising and creating a swirl pattern. You want the swirl pattern so the air flows horizontally out past the valve as the valve head blocks the vertical path. Single valve heads should have a snail shell like pattern around the back of the guide, or a ramp that starts at the front of the guide and drops at the rear of the guide, and twin cam heads only need the area where the port splits into 2 to have a "knife edge" on it and same in front of the guide ************************************************************************************ Valve Seat Angles Most alloy heads these days come out with the 3 angle valve seats, 30° crown 45° seat 70° throat (bowl/ port side) valve lapping is possible to get the seats to seal but what it is actually doing is bedding the seat's 45° angle into the valve creating a indented area on the valve face, which carbon can build up on it over time and create a non sealing valve again Flow testing has proven that adding a 58° between the seat and the throat increases the head flow on the intake seat. Radius' are a continuous round seat, these are best for the exhaust side with a minimum of a 1mm wide 45° valve seat angle. The radius is not good for the intake as it disrupts the atomising processes After seat have been cut and the springs on a "leak down" test should be performed, with the manifold side facing up pour a liquid in, and if any has leaked through in a couple hours then it is not sealing 100% ************************************************************************************ Reconditioning Cylinder head The reconditioning process is maching the head so its just like new. The following is the process in how it should be done Strip and inspect cylinder head, CC chamber Acid bath head and parts pressure test cylinder head - report to customer if no good organise parts if needed bead blast valves face and machine valves bead blast head run a tap through all bolt holts inspecting for damaged threads, repair or helicoil if needed Remove and replace guides if needed Remove and replace vavle seat inserts if needed cut valve seats making sure they seal 100% adjust shim lash adjustments if it has solid lifters/ clean and inspect hydrualic lifters machine head gasket face to within tolerance of original head cc's de burr and final wash of head assemble with new welsh plugs, oil gallery bungs and valve stem seals ************************************************************************************ Reconditioning Block Reconditioning of the bottom end Strip and inspect measuring every bore, tunel, journal in the north south, east west fashion acid wash everything organise new parts if needed linish crank - grind if not within specs remove any press in bungs to help clean out and dirt and sludge that may get stuck behind run tap through and inspect every bolt hole bore and hone block, finers stones for allow bores and chrome moly rings chamfer top of block wash dummy assemble and get deck height work out compression ratio and see if it matches OEM specs close and rods conrods if needed, remove and replace pistons if needed wash everything asseble or send back to customer in "kit form" ************************************************************************************ RB series specs ARP RB Main Stud Torque settings 73-75ft lbs ************************************************************************************ RB20 bore 78mm/3.071" stroke 69.7mm/2.744" main crank journal 2.1634" / 54.951mm to 2.1644" / 54.975mm big end crank journal 1.7699" / 44.956mm to 1.7706" / 44.974mm main tunnel 2.3089" / 58.645mm to 2.3094" / 58.658mm con rod big end tunnel 1.8897" / 48.000mm to 1.8893" / 48.013mm ************************************************************************************ RB25 bore 86.00mm/3.39" stroke 71.70mm/2.82" main crank journal 2.1634" / 54.951mm to 2.1644" / 54.975mm big end crank journal 1.888" / 47.956mm to 1.8887" / 47.974mm main tunnel 2.3089" / 58.645mm to 2.3094" / 58.658mm con rod big end tunnel 2.0079" / 51.000mm to 2.0084" / 51.013mm ************************************************************************************ RB26 bore 86.00mm/3.39" stroke 73.70mm/2.90" main crank journal 2.1634" / 54.951mm to 2.1644" / 54.975mm big end crank journal 1.888" / 47.956mm to 1.8887" / 47.974mm main tunnel 2.3089" / 58.645mm to 2.3094" / 58.658mm con rod big end tunnel 2.0079" / 51.000mm to 2.0084" / 51.013mm ************************************************************************************ RB30 bore 86.00mm/3.39" stroke 85.00mm/3.35" main crank journal 2.1634" / 54.951mm to 2.1644" / 54.975mm big end crank journal 1.9670" / 49.961mm to 1.9675" / 49.974mm main tunnel 2.3089" / 58.645mm to 2.3094" / 58.658mm con rod big end tunnel 2.0866" / 53.000mm to 2.0870" / 53.011mm (any advice given here is more based on a 'push in the right direction' if you dont fully understand parts of this. or a job, ask some one for help, re read info, google or leave it to the professionals)

Yeah but they aren't too familiar with rb's, they seem more rotary based. Is hard to find someone who knows rb's n/a cars and haltechs with out the "that will do" or "that's close enough" attitude aim is to have it ready well before the all jap day at silverwater on Nov 13 and there is stuff i need to do outside the tune

Yeah i actually have been thinking about doing the 90° angles. though all depends on how the linkages are set up

Update; Micks motorsports: you'll have the car back in 2 weeks 2 weeks later Micks motorsports: you done a shit job with the linkages me: *face palm* lol ok so how long? Micks motorsports: well i won't be able to start it for a few weeks but ill try to get it back by end of July end of July Micks motorsports: we're flat out not enough hours in a day me: look at your work load and give me a realistic time Micks motorsports: end of august beginning of September end of first week of September Micks motorsports: haven't had time promise end of next week end of the next week Micks motorsports: not ready, won't be able to start it until the week after next, got a race meet on next weekend. But you will have it for the long weekend (the photos above were taken then) yesterday was well past 3 months since i took it to him, nothing has been done since i left it there. every other car gets put inside his workshop and mine is protected by a crappy fence and pad lock. I took it to him cause i know he is the best with Japanese cars and n/a cars but obviously he doesn't want to work on it, and being the only car out the front shows he doesn't care. So my patients has run out. Time to look for a new tuner (i know the forum rules, you can't dis a business, I'm not saying he does a shit job, and ill still stand by what i say, he is still the best i know of with what he does, i took it to him knowing he is not the quickest)

I have 10.8mm lift cams 10vc dome piston and 0.130" intake and 0.180" exhaust piston to valve clearance. but i also have +1mm valves and 0.095" ground off the head and the pistons are sitting above the deck 0.005". Minimum piston to valve clearance is 0.080" And ac/dc were are good band in the day

All cams will cause loss of compression with valves being open during the compression stroke I.e the cams i got are 252 & 262 @ 0.050" at 10.75:1 static compression ratio dynamic compression ratio is roughly around 8.5:1 Valve over Lap is when the exhaust valve is closing and the intake is opening at the end of the exhaust stroke/ beginning of the intake stroke Adjusting cam timing via dialing in which should be done with all new cams or on a dyno / series of road tests etc and this will change the valve overlap and can add or take away a percentage of the compression stroke

Too add to this, with rb26s having a 12mm head bolt hole it makes the block material a little thinner and they usually crack from the head bolt hole to the water jacket also if the block and head don't have a 7ra finish the metal head gaskets can leak via the grinding/ milling marks

A good machinist can machine anything and be consistent with the sizes, blue printing is making every cylinder identical but with parts these days having better technology for better consistent quality, you find blue printing bearings and pistons don't need to be done these days and a tunnel bore is machining the main cap parting faces then boring back to factory size. over size bearings are for crank grinds

Main clearance 0.0004"-0.0029" Does the crank need a grind or a linish? has it been ground before? Unless your going main studs a line hone isn't needed often

Depends if that's a common job to them

1st: yes up to 10.8mm lift, you will need to machine out head and as bubba said solid lifter conversion and make sure you get springs to suit the valve lift 3rd: 1 in about 20 blocks can be successful in machining for squirters. best bet is make sure the rods have the little squirter hole in them not as good but same idea 5th JE/ srp, cp, only pistons i recommend, mahle hypertech few others out there 6th how long is a piece of string? Nitto gaskets come in 1.2mm, 1.5mm, 1.8mm thick with 88mm gasket bore, plus deck height piston dome volumes combustion chamber volumes... best to leave to machinists

Oh and some more photos

No simulator used the trumpets follow 1 rule, shorter for higher rpm/ top speed, longer for more torque. i wanted torque but didn't have the room :-( Headers are the same as the hurricane rb30 interference length with a rb26 bolt pattern welded on, but soon as i get the funds ill take it to a guy i know that will work out the right length for the block volume, comp ratio, cams, porting flow figures etc, they will set me back 1800 For now im just focusing on getting the car back

Crank angle sensor sits on exhaust cam also the timing marks on the backing plate on the head are not the exact timing marks when you use a 30 bottom end with a 25/26 head. i don't know the exact spots but might suggest to get the cam timing done on a dyno

Ive done a few solid litter conversions at my machine shop tweak it can supply the tomeii solid softer kit, they will come with the valve to cam clearances. Since your chasing a rev range buy all parts that will work in that rev range, most the time departs manufactures will state the products rev range. pretty much every stainless steel valve ive seen for the rb motors have a + 1mm head make sure you get valve springs to suit the cam, supertech and ferrera are the only parts id recommend flow bench porting 4-5 angle intake seats and radius exhaust with 1mm 45° seat

Still waiting, got angry's coilovers though. car should be back soon hopefully, am getting a lil impatient but they are over booked and under staffed exactly how we are at work

If its hydraulic rb25 the retainers should sit slightly above the collets with a large amount of valve tip sitting above both, converted to under bucket shim or rb26 the retainers should have the section to locate the shim. if its hydraulic still then obviously you were supplied the wrong retainers

Valve tip to retainers all over the place.... this measurement has no relevance ever. Valve protrusion measurement from spring base to tip of valve for help with setting the shim clearances in rb26's neo rb25's or rb25's with solid lifter conversion with the rb25 being hydraulic the valve tip length has only one purpose which is to sit above the retainer and that's it. Fererra parts can only be used with fererra parts, spring bases springs retainers valves valve locks etc the hydraulic and shim buckets don't need to change to suit the valve train manufacturer stainless steel valves will need the bronze guides or bronze sleeves otherwise the friction will ware both the guides and valves out +1mm valve head hope you intend to get the seats re cut 10.25mm lift good chance that you will need to machine / die grind the head out. also you will need to re check the cam base circle to top of bucket clearance (18 thou intake 15 thou exhaust) All this work you may as well get the head flow bench ported professionally and send the head to a machine shop so the job can be done right the first time

Yeah i know, i guess its a good change then posting up an exhaust question. We really need p plate repellent spray or something

Isn't there another section for this?

Is she a good sort? Any questions or main topics anyone wants us to focus on?

The machining thing i mentioned will have the nitto guys here as well just got to find a suitable date around February / March

Rb25 & rb26 I've seen all varied from 62-67. Neo's from 52-56. The first 20 thou ground off an un machined 25 & 26 head removes exactly 2CC's and it always varies from there piston to deck heights varied too, rb30 with rb25/26 pistons 10 - 40 under rb30de pistons 20 thou under to 10 thou above 5 thou above will usually add .25 to the comp ratio a 1.8 gasket replacing a 1.2 can lower the comp by around 0.75