Let me start off with the statement that im typing all this in hopes of passing some knowledge off to people who really want to learn about building engines. Im also hoping this can get some sticky love. Im going to go over alot of basics about bore, stroke, block prep, part prep, cam selection, rod length exc. I hope this helps and anybody please feel free to add to this as there are alot more experienced engine builders on this site than me.
Lets talk cylander bore first. If your doing a rebuild and you are trying to increase cubic inchs by increasing bore size. First thing that needs to be done is go to a machine shop and have your block checked for core shift and cyl wall thickness. That will give you a idea of how far you can go. Now over boring a block can hurt you, to thin a wall will allow the cyl to flex under load causing poor ring seal and increasing wear. You can regain block strength by filling your block with a concrete based filler. This will decrease cyl flex and in result strengthin the upper part of the cyl as well allowing you to safely run a bigger bore. Now you must know you dont want to fill the block completly full for street use, only to the bottom of the freeze plug holes. Most of the heat isnt untill the last top inch of the block, as long as your cooling system is up to par you wont run into any cooling issues. Also make sure your machine shop has a honer that is of stone/wire brush type so that the stone material doesnt get imbeded into the cyl walls on final hone after the bore. Still be sure to clean your bores good after you get your block back with soapy hot water and a scuf pad to be sure theres no stone debree beded into the walls. Youll know your clean when you wipe your bores out with a paper towel and wd40 and dont get any gray material on the towel. Also be sure they chamfer the tops of your bore lip. Any quality shop will do this, if they dont i wouldnt return there for future work but thats just me.
Lets talk stroke for a quick sec. Now for the quad platform theres really no option for a stroker crank that i know of, other than grinding down the mains of a ld9 crank and putting it in a 2.3. Now eco guys im not sure if you have any stroker options or not so im not going to dwell on stroke too long. Longer stroke and rod lenght for that matter is always better in terms of making tq witch makes more hourse power and uses more of your bore and incresses cyl life. A longer rod and or stroke also makes for a smooter running engine as well. If you want to rev to 11,000 rpm a short stroke and rod will more than likely sute you the best.
Block prep. Preping your block is very important and this is were i get all ocd about stuff lol most people just get there deck done and bore/hone and call it a day. After having your block sonic tested and checked for core shift its a very good idea to have your block baked and shot peened to relieve stress from the block. Oil return to the pan is critical as well. Weather you are running a dry or wet sump system its critical to make sure your pan always has plenty of oil in it to ensure you dont starve the system at high rpm. Deburing and opening up all of the return ports is always a good start to letting oil fall back down to the pan. Also good pratice to prevent sand traps. I also like to smooth and polish all the surfaces in the block so it runs to pan quicker. Opening up your oil gallies by boring them doesnt hurt eather by allowing higher vollums of oil to get to where they need to be. Also be sure that if you have your block bored its best to be done with a deck plate and its wise to have your block decked true to the mains. Deck serface prep is critical as well to ensure a proper head gasket seal.
Crankshaft prep. If your crank needs ground due to scoring or damage dont be afraid. Most people believe that when the journals are ground down it makes them weaker. This is false, when the cranks journals are ground smaller it increases crank fillet radii witch makes the crank journals stronger. Getting oil to shed faster off the crank is another way to gain tq/hp, as well as a faster reving engine. Knife edging is a great start, removing the casting edges gives oil one less place to cling to. Polishing the counter weights is a huge help as well. Oil doesnt cling to smooth serfices well at all. A spinning crank will sling the oil off like butter. Like mentioned earlier the block walls polished as well will be a polished counter weight cranks bff. Of course with any crank mods youll need a ballance job after words.
Cam selection. Cams are a thing that require alot of research so ill just go over the basic rules of picking a cam since everybody will want and need something different. The whole engine dictates what your cam spec should be. A high compression engine needs more duration to prevent to high of cylander pressure witch will cause knock. Of course higher octane fuels mean you can run higher cylander pressure witch means less duration and a more street friendly engine. Every ones idea of streetable is different, most high rpm engines are not that street friendly because you dont make alot of usable power down low. Meaning they need reved out to get going. Longer the duration the higher the rpm band will be for power and the higher the lift the more air you can get in, witch means the more fuel as well witch makes more power. You can go over board with lift, its wise to have your head flow tested before picking or ordering a custom ground cam. Once you get your flow sheet youll see at what amount of lift you head flows the most air and that number is what you want to stick as close to as possible. The purpose of the engine your building will help you pick your rpm range or duration of your camshaft. Do you want to make alot of power down low to haul? Wanna make good overall power across the rpm range for a good all over engine, or do you wanna high rpm all out race engine? Those are the basics of picking lift and duration. Now lsa or lobe seporaton angle is another thing needing chose. In most cases the higher the lsa the more boost friendly the cam is and the lower the lsa the better for a n/a engine. Just a general rule of thumb to help pick lsa of your cam. Timing events also come into play as well. How long do you want the valves open and how long do you want them to over lap? Too much over lap will cause too much of a cyl pressure drop and kill power and yet not enough will cause excessive cyl pressures forcing for higher octane more expensive, harder to find fuels to be used. Most people also feel duration herts a boosted engine, well what i have to say is that a engine is a fancy air pump and the more air and fuel you get in, burnt and out the better. That leads to more power, but ill leave that for you the builder to decide.
Piston choice. Once again whats the engines purpose? If n2o is in the works a good forged pistion should be in your budget. Hypertechtonic and cast pistons can be damaged by the high temps n2o can cause and piston melt down is not a good thing lol plus a good forged piston is light witch will make more power, rev faster and cause less stress on the bottom end. Less stress means longer bearing life. If no n2o is in play a nice hyper piston can be a good thing. Hyper pistons have a high silicon content and dont expand as much as forged pistons when hot meaning you can build closer tallerances and better ring seal. Piston coatings are a great thing as well, a anti friction coating on the skirts and temp coating on piston face will lead to longer piston and cyl life. I always recommend oil cooling your pistons reguardless the application, ld9s come stock with squrters drilled in the connecting rod big end. Or you can have bosses drilled in you block and meters pressed in to spray the back side of piston to cool it. This can drop piston temps 200*f, also a plus is the oil further lubes the cyl walls yet again increasing cyl life. Picking your pistons also effects compression ratio and based on dome shape, quench. Im not a pro on quench so i wont get into that because my knowledge is very limited on that subject as of right now.
Cylander head. The cyl head effects alot in a engine. What you do with the head needs to be based off your needs and wants of your engine. To big of intake ports will drop low end power but gain up high when air flow is in high demand. To small and you cant build much power at all. Smooth ports flow air smoother and faster but a ruff cast and some port shapes promote swirl effect and help fuel adimazation. The shape of the port and the angle the injector sits also has an effect. If by porting you can remove material that lets the injector have a cleaner shot at the back of the valve, with out oddly shaping the port hurting flow, than you reduce the chance of fuel puddling and keep the back side of your valve cleaner as well. Alluminum heads save weight and disipate heat faster, if you over heat tho they warp easier as well so keep a eye on that. Ive seen alluminum heads drop seats when over headed, tho that was a burried neddle on a 3.7 mopar in a commander just never over heat your engine espally an alluminum head, getting a couple miles further down the road isnt worth you engines life!! Combustion chamber size and shape also impact cyl cc, compression and quench. As well as head deck hight effect those as well. Valve material is just as important as any other part of the engine along with valve size. Stainlass valves are stronger and lighter than steel stockers. Better even yet titainium is super light and strong. Increasing valve size will yeild higher flow numbers at lower lift numbers to allow you to run high dome pistons or to shave your head down further both allowing highe compression with less worry of valve to piston interferance. You can get off shelf or custom locks and retainers maid of titainium as well saving weight wiitch again makes more power and less vavle train stress, longer valve train component life and quiter valve train as well.
There are meny contributing factors to a whole car working other than the engine. Im only helping with a part of the puzzle. There is alot more to a stout engine than listed here but i gave you alot of the basic and lesser coverd info on engine building. I hope this helped whoever was looking for this info and thank you for taking the time to read this as well guys and gals
:-) feel free to add and comment its your first admindment right after all!!
Cody Nobbs
N&F Performance
I Love My J ♡
I really wish i still had my premium membership so i could edit because i forgot to proof read and spell check :/
Also want to talk about piston rings. Im not a pro on ring material, i usually read up before i buy as i havnt re-ringed a engine in a min or two. Ring thickness comes into play as well, a thinner ring might cost more coin but will lead to less friction once again making more power witch is what we all want!
Engine temps are another power maker or killer. Optimal engine coolant temp for making power is 170*f, optimal oil temp is 210-220*f. Oil temps up to 210-220 from 160-170 is worth 7hp at 7,000 rpm in a sbc. Just using that as a reference, not alot of us j body peps are running sbc engines.
Alot of the little things i have mentioned might not seem worth the hassle. When you put it all together as a group, a couple tq/hp here and a few there can add up to 10,15,20,30 hp by time your said and done. Thats the stuff that gives you the extra little edge on the other guy and really helps in cases were there isn't a lot of aftermarkets parts availability. Ever little inch counts and adds up, its the attention to detail that makes the difference.
Cody Nobbs
N&F Performance
I Love My J ♡
I would NOT fill a LD9 or any quad 4 with the block strengthening filler. You you be closing to many of the cooling jackets. They may be fine on a V8, but I would advise against it on a quad 4 based engine. There is also, little need to do this on a quad. Most quads can be bored 0.020-.040" larger with no issue at all. You can a LD9 all the way up to a 2.3L diameter, if there is no core shift. The 99-02 blocks seem to have a lot less core shift than the earlier years. 00 LD9 blocks seem to be the best so far.
The Rod/Stroke ratio in my opinion is a much better way to determine if the engine can spin to a million RPM or not. 1.75:1 is ideal, and is very close to a stock quad 4s ratio. The LD9's ratio is lower, but with longer rods, and offset wrist pins a LD9 can easily get to the ideal of 1.75:1. Some of the really high revving motors go all the way north of 2.1:1, while the high revving Honda guys are down close to the 1.5:1 ratio. I do not even want to get into the air pump effects Rod/Stroke ratio have on an engine. You can actually make lower power-band RPM torque with shorter rods, than longer rods.
Knife edging and polishing the crank is all and good, but what about the windage trays? Most LD9 guys end up swapping one in when the do the 2.3l oil pump swap. In my opinion windage trays help more than knife edging and polishing.
Lighter / Stronger parts are the way to go 99% of the time. Less rotational mass lets to free up HP to go faster.
PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO
Pretty decent post. I wanted to touch on part of the cam selection: LSA:
In my experience, the power band is more of a consideration when chosing LSA than whether or not an engine is boosted. A lower LSA tends to lend itself better to high RPM horsepower, and higher LSA to lower RPM torque. That being said, knowing the flow characteristics of the head will help you balance out the lift, duration, and LSA to get the optimum volumetric efficiency from your engine. Another thing to remind people about is that with the DOHC engines, LSA is adjustable, as the intake and exhaust lobes are on different cams. With the advent of VVT, this becomes fully tunable, which is how modern engines maintain far flatter torque curves than used to be possible.
I would recommend trying to find real-world tests on any cam(s) you are considering to see how they have performed in a similar situation. Sometimes there are cam choices that seem to defy the rules. I have seen a very streetable turbo engine with good throttle response running a cam with a very low LSA.
Thanks guys for commenting!!! Mike i was not aware it could be detrimental to a quad based engine to be block filled as ive never done so. Thank you for adding in as well with rod ratio. An quick thanks for adding in on lsa, i feel a informative thread like this is needed and would be of great help to people looking to building a strong engine for there car. Mike i agree on the windage tray being the biggest part of it and cant believe i left that out. Thanks guys for jumping in and the added info!!
I Love My J ♡
Touching on the subject of filling a quad family block... I know of a 332hp NA 2.5 stroker Quad 4 engine that has been filled. How much, I do not know. Just remember the owner telling me about it when I was going to buy it. To my knowledge there were no known issues with cooling. You can run E85/meth injection to get a cooler running engine if that's the worry. However... even with thin walls, I have YET to see anyone ever crack a quad 4 family cylinder wall due to it being too weak. With that said, I could have missed one but you would think after many 500hp builds as well as nitrous sprays this would become an issue. It really is not. Would I fill one? Probably not but then again I don't even see the benefit to it, so...
On the subject of cams, well, there are sooo many builds out there with an eclectic array of cam options. Ho cams seem to be the best one on average for NA or boost. Two of the highest hp M45 builds are running/ran Ho cams. The highest NA motors around here are running/ran Ho cams. The highest turbo motors around here are running/ran Ho cams. They really are a godsend for us and I really wish more people would have ran them earlier in our "scene" so to speak. In the end, yes.. a custom ground cam profile done up exactly to your engine flow characteristics is going to best, however... finding blanks these days is only getting harder. Last I knew a custom billet set would run anywhere from $800-$1600 dollars. Up to you if you want to find that extra hp but IMO if you aint got the blanks and cant find any, just run HO's.
For the cranks, well, knife edging may or may not be worth it. To that effect, you are STILL removing weight off our heavy as hell crankshafts doing it so I say its worth it. Windage trays can only go so far... with these engines spinning high RPM, the oil physically gets SUCKED up from the pan and onto the crank. It wraps around it dragging it down and causing a loss in HP. Up to you if you feel the need to go there. I did on two of my builds already and would not hesitate to do it on another. One thing old super stock racers used to do was run their engines low on oil to try and avoid this, freeing up some HP. While doing the 2.3 oil pump swap and physically lowering the pan depth, you can get away with running the stock 4.5 QT amount and it would literally do the same exact thing. Keeping the oil level LOWER in the pan instead of running the 7 QT maximum most set-ups are able to run quite possibly could help to alleviate the need for knife edging but again, its still weight off the crank.
Rod length, I say the longer the better. The LD9 is already a "Stroker" in the general sense. And in the general sense, I have always read that in stroker motors you want the longest possible rod so it will slow the pistons down and lower side to side pressures. Not only will longer rods allow the pistons to stay at TDC and BDC longer creating more cranking pressure and allowing for more "fill", it will lower friction caused by "side-loading" freeing up hp in the process. Our engines are straight up and down so its not NEARLY as big a deal as it is in say a V8 configuration but every little bit helps.
Rings, Total Seal has been touching on using ring spacers to allow the use of thinner ring packs. Doing this lowers friction and in turn frees up hp. I don't know if they offer spacers and the thin rings for our size pistons or not but you could always order your pistons with a ring groove capable of running them, IF they offer them in our sizes. I haven't looked into it yet but I certainly would like to.
Ive never heard of the optimal engine coolant or engine oil temp before, that's pretty cool. I always knew that heat builds hp but there is a point when you want to back it down. Like I said earlier, alcohol fuels can do this for you all day long. The oil temp is interesting... one could always play with different size coolers, etc to get to that optimal point. Ill be looking into this for sure...
RIP silver car. You will be missed.
Just to put it out in the open air for all, web cams in cali did tell me they would hard weld and regrind our stock cams to any spec for $800US. i still hant called colt but all the other companys ive called said they cant. Food for thought guys!!!
I Love My J ♡
Still think it is better to take a stock 2.3 cam and mod it to work in a 2.4...
HELL of a lot cheaper too.
'02 Z-24 Supercharged
13.7 @102.45 MPH Third Place, 2007 GMSC Bash SOLD AS OF 01MAR08
It bugs me that no one ever touches on compression ratios in posts like this. Both static and dynamic compression ratio make a huge difference in the power potential of an engine. Long duration cams or ones with late intake closing with a low or stock SCR is going to make @!#$ power because its bleeding off what little compression the engine already has. Compression is the BIGGEST factor in brake mean effective pressure, (bore, stroke, etc also play a part), which is what makes power. From what I've seen in simulation (like $20k OEM type software), SCR shifts the power and torqueband straight up. Its basically a scalar. As long as you can tune it, more compression is the way to go.
Also, I'm not a huge fan of R/S ratio for evaluating an engines potential ability to rev. It does give a rough idea of how piston speeds vary between applications, but that is a small portion of the equation. Rotating mass and undersized hardware will play a bigger part in breaking an engine. Its just coincidence that all of the "high-revving" engines that everyone talks about have close to a 1.75 ratio (a Honda B16A for example). There's built Honda racing engines will R/S ratios near 1.4 and 1.5 that will turn 11k RPM all day long and Formula-1 engines typically hover around a 2.0 R/S.
Here's some of my inane ramblings from 2 years ago when I started coding my DCR calculator.
Taetsch Z-24 wrote:Still think it is better to take a stock 2.3 cam and mod it to work in a 2.4...
HELL of a lot cheaper too.
Agreed. That is why I'm swapping a LG0 based engine into my 99....I still want to build a full LD9 block though....
Brian, glad you brought your old post up.
PRND321 Till I DIE
Old Motor: 160whp & 152ft/lbs, 1/4 Mile 15.4 @88.2
M45 + LD9 + 4T40-E, GO GO GO
Im glad everybody keeps adding to this!!!!
I Love My J ♡
Very good read btw brain!!!
I Love My J ♡
Thanks! This is actually a really good post overall. I'm glad you took the time to write it up.
Im glad too! I just havnt seen or found anything this indepth so i wanted to try and put it in a good place. Like i hoped as well its getting added to as well with even more amazing info!
I Love My J ♡
I Love My J ♡ 
