Got Head? RPM Question.
 

The new head I'm building for my 1.6 NA will be the first head on this car that I've devoted so much time and money toward. It's getting 32mm and 27mm valves dumped in it with dual valvesprings (rate is 12 flat per mm and lift is 125.3 @ 10.3). I don't really care about the inertial stress (read: rotational effort) caused by the dual spring setup. My question is what kind of RPM can I expect to get from this setup before I get valve float with cams that have around (I say around because I'm not set on a profile yet) an 11mm lift? The springs are good for 15.8 max lift. Yes, I know, I put random information all over the place and it's hard to read, but hey... I can't spoonfeed you guys. Geeze.... Oh, I'm sticking with the hydraulic setup because I'm cheap.

Any insight is appreciated... even the useless, misleading and generally non-constructive posts are encouraged for daily humor. Thanks in advance.

Oh, and yes it will be ported and polished and port-matched and have a 5-angle job and blah blah blah. That may all be a given but I figured I'd throw that in there just in case.

Also note that I have talked to the machine shop and they are suggesting using the camshaft RPM power-range specs, which is stupid because those change based on timing and the Mazda guys say nothing helpful at all: "You should never, EVER exceed the RPM specified on your tachometer that is indicated by the red warning lines." I'm pretty sure everyone that I call hates life in general and feels like being a complete douche, so here I post.

Did last night. Might I ask what kind of motor build/turbo you are working on to need more than 7500 RPMS?

I don't see anything mentioned. But anything over ~7800 causes all sorts of fun Harmonics and the oil pumps blow up and ruin nicely done motors.

Might want to take that into account.

^ The higher your RPM celing in terms of effective breathing, the wider your powerband. A wider powerband means more time in the lower gears and much better acceleration. In the end the only really significance of HP is that it indicates how TQ and gearing (in terms of RPM capability) work together to accelerate you up the road.

I am definitely interested in this too. Having power start well below 4K is great, but if it continues to 8500 or something, then your gearing gets much much more useful. Imagine if you can stay in 2nd and 3rd for an extra 1000 rpm without power dropping off :)

Good point. Something like an ATI might be a good idea. Boundary pump is probably a given too.

Forged, maybe 0.60 over, but at least 0.40, sleeved if it's 0.60 over, 8.5:1, I think the head gasket is .2 thicket but I'm not sure. Inconel exhaust valves, OEM HL's... I dunno what else to tell you. It's going to remain small displacement so I'm going to stick with a small compressor but get it all polished out so I can spin it a bit faster, so a 28 series will be biggest that I'll go. I'm shooting for low torque, high power (obviously at high[er] RPM).

I'm not using an OEM pump, so hopefully that fixes the problem.

That would be ideal and that's sort of what I want to get at. But I don't know how much the OEM HL's can handle before RPM increase becomes a mute point. That way I can get more out of a close ratio and have the duration of a wider gearset... kind of, ha ha.

Your rods/rod bolts will limit you long before valve float will. By limit I mean, fly out of your block.

This has been discussed adnauseum, you are not the first person to modify a 1.6 head. You haven't even spent a lot of money yet. Search.... You'll find some posts, I know because I made a bunch of them like 3-4 years ago.

Three to four years? Damn... that's lots of searching. The block it's going on is going to be built to withstand well over 10K RPM and loads of boost. Everything's being balanced and I'm getting the crank knife-edged, even though it does bad things down the road. I'm not putting a built head on a stock block or even just a block with forged internals, that's a waste of money.

Searching is only as good as the user inputting the search terms.

I know, ha ha. I'm still searching. You just recently blew your engine didn't you? What went wrong?

I fully built my 1.6L and kept it at 7800-8000rpm above that im not making anymore power so its useless.

First of all if you are going to put this head on a well built bottom end, why would you skimp on lifters? Do not do that. Second, it is better to match the camshaft with the proper springs. Anything too week and you get valve float, and loss of horsepower. Anything too stiff will also result in a loss of horsepower. Keep in mind that if you use a lightweight shim under bucket lifter, you will need less of a spring to keep the valves from floating. It adds horsepower too. It is a good investment. My best advice, is to contact your cam manufacturer on the best combination of portwork, valvetrain components, and camshaft.

Another thing, there was no mention of duration. What will the duration be, particularly at .050 inches lift? The duration is what will effect the rpms the most.

How fast did your power taper off past 8K and how much did you play around with cam timing? It wouldn't be hard to make 8K a target as opposed to higher, especially if cam timing is essentially beat out my physics beyond that point.

Duration is 287... I think, ha ha. I'll have to get back to you on that. So get the cam manufacturer to suggest components and porting, hmmm. Would I be better off just going to Wiseco (first name that popped in my head) and getting them to cut me cams based on what I want and letting them deal with components and giving me an outline for porting? I guess any place can make me springs and valves based on what I want. I'm skimping on lifters because I think it's going to exceed my budget to convert to solid. If I exceed budget, then no engine goes into the car, which saddens me.

Wiseco makes pistons, maybe you meant Web Cam or Integral.

--Ferdi

Integral has some very good packages under a grand.

I was considering a pretty serious head build when looking at building a motor, but am now just sticking with some basic porting.

Anyhow, they can easily tell you what combination of their 3 levels of cams are for you, match springs and lifters, and tell you what their operating range is.

Just curious, but why would you sleeve an iron block?

:BSmeter:

You are getting in a little over you head. You need to learn more before posting. It sounds like you are portraying knowledge that you do not yet possess.

The wolves can sniff out weakness, and the stench is strong.

If you want a max effort 1.6L motor, you need to maximize the airflow of the 1.6 head. You are going to have to spend some money to get maximum flow out of the 1.6 head; oversized valves, professional porting and converting to a solid lifter setup capable of supporting a lot more lift than the stock HL buckets. The port work to be done differs if you stick with stock style HLs; no need to work on flow at higher lift rates (.400-.450) if you can only get to .380 lift with HLs. Cam choice can't be properly spec'd (e.g., running a simulation) until you know cylinder head flow at various lifts, compression, intake, turbo map etc. Springs and retainers can't be selected until you know the lift specs and lobe acceleration specs of the cam.

I don't know, ask the guy who is going to be doing the machinework.

Duh, why do you think I'm asking? I have an idea for cam profiles but I figured I'd ask about the limitations of the factory HLA before I went RPM happy and wrote my new engine's demise. Someone asked for the duration and I gave them an idea of what it may be. It's not like I can give anyone a specific number when I haven't chosen, yet. How about this: I'll PM you progress of the build (both what I do and what the shop does) and then a video of the end result (after tuning). Then, when you are satisfied and see that you, nor I, are not a wolf, you can start a thread telling everyone how much you love me and that you wrongly judged me. I think that seems fair.

Oh (to the other guy), and no I did not mean Web or Integral. I said Wiseco because that is the first company that popped into my head. Geeze. I know they don't make cams, I just threw a name in there for an example. I'll be specific next time in case you don't read what I typed in the parenthesis after.

This is starting to sound like I should tell the shop what I want and tell them to make it work. And I don't want a max effort 1.6 that I'm going to have to rebuild every ten thousand clicks; I'm going to drive it around when the weather is nice.

I will give you the benefit of the doubt, but I still think you may need to tone down your goals. A camshaft with that kind of duration will not work with HLAs. Go with a smaller cam.

My advice to you is to not get carried away with building a monster motor that spins a high rpm that the rest of your combination will not work with. Monster motors need monster transmissions, rearends, suspension and saftey equipment. Start out with a well rounded combination of parts that all work together. A good example, is if you have a very high reving motor, you will need to change the rear gear ratio to make it work properly to your application. I have a pretty mild cam, but to get it to really work with the horsepower and application, I had to put a lower gear ratio (4.44:1) If the bugdet does not allow you to invest in your diff, you want to run a milder cam. Same goes with valvetrain components. Do not go all out on one thing, and skimp on another. You will have wasted money, and your car will not perform as well as someone who went with a milder setup, but has all the parts working together.

Also, you need to gain experience before going crazy. You will learn the hard way that radical motors do not fair well with tuning mistakes. Gain experience with a mild set up, and then when you have the know how, go big.

All that head work and retaining those heavy hydraulic lifters...If your buildig the head you better have an equally well flowing intake manifold ( ie custom)

Yeah I've been talking with Kelford and they want to cut cams based on what my target numbers are and my powerband. And you don't have to give me the benefit of the doubt, I was just being a douche, ha ha. Giving half-assed information will lead to posts like yours, which is perfectly fine and expected, since I gave half-assed information, ha ha.

I already have a Quaife gearset (which should off-set the rearend, given the higher-than-factory engine RPM), 1.8 flywheel/clutch get-up and the suspension should hold enough of its own until I need a new set. As far as safety equipment, I can put my bolt-in back in until I get a weld-in setup.

Yeah I skimped on the engine this time around, which is why I'm not at my ideal power numbers, which is the reason for this build.

I hate tuning. I'm letting the shop do that. That way they can front money for a rebuild if anything goes wrong (I already checked and they don't have any sort of waiver).

Of course. I know the HLA is around a pound or so of mass, but if what I want can work with the OEM setup I'd rather not swap out to a solid setup and shims. Pain in the ass.

Best 1.6? A destroked 1.8!
 

I know you don't want to hear this BUT:

If you really have high power goals, you start with the engine combination that has the best stock airflow and the best potential airflow (in NA/NB Miata land, that is a 99+ head and solid lifter cams (fitted on your 1.8 block of choice). Engine power and torque is always capped by how much air the cylinder head(s) can flow regardless of whether the motor is NA or FI.

Given how much better the NB 1.8L head flows vs. the NA 1.8L head (which flows significantly better than the 1.6L head), I really wonder why people bother with "big builds" on 1.6L heads unless they are racing in class that specifically limits them to a 1.6 head on a 1.6 block.

If you want a inexpensive, badass 1.6L motor, destroke a 1.8L NB to 1.6L! It'll make more power with a stock head than a fully built 1.6L core and be a lot easier and cheaper.

It may sound like sacrilge to some but if you want high rpm low torque high hp why not save yourself a lot of machine work and just put a rotary motor in it.

I never thought of this. That's a pretty good idea. Why the hell do I never come up with good ideas when it comes to my own stuff? FML

I thought about it and was swiftly reminded how much I hate rotaries when I got stranded on the highway in a friend's FD. No thanks.

invest in an ATI harmonic balancer. They are the best and for a high revving motor you need to keep vibrations under control....

Done and done.

ok i think im one of the only people on here with a seriously built head.
although mine is a 99, same things should apply. also i work for a race machine shop.

as far as your springs are concerned. you cant choose springs before a cam, thats not how it works. your cam manufacturer will give you spring requirements for that specific cam.

i am running integral R1 exhaust cam and R3 intake cam.
my gross cam lifts are .490 intake and .458 exhaust.
my cam sheet has all the info i need to run these cams. they are rated for 9000 max rpm

the spring requirements for these cams are 49lbs closed and 156 lbs open. that isnt alot of pressure. i have supertech dual springs. i had to remove the inner spring because it was way to much pressure something near 200lbs open. so i use just the outer spring and a shim to make the pressure right, its been a while but i think i set them up around 160lbs open. its important not to run an over agressive spring with agressive cams on a flat tappet lifter like ours because you run the risk of rounding over the cam on initial start up.

before you choose cams you need to have an idea of what your head flow. i have access to a flow bench so i flowed my head to get exact numbers to choose cams. for example. my head flows 246cfm at .500 lift@28"h20 . after that it fell off. so thats why i went with such a big intake cam to have the valve operating where the head flows best.

everything has to work together. a word to the wise, anyone planning on running high rpms. you have to address alot of areas, its not a matter of making your head work in the area, you need strong rods, a balanced bottom end, the lighter the rotating assembly is the better. billet pump gears,and a ati balancer. and NO!!! hydro lifters. when you put in massive cams your motor has the potential of becoming interfearence.

BUT. How do you like the setup? Are you NA? What sort of abuse does the car see?

i havent fired the motor yet, i can just give advice on building. the car is track only. turbo 400+ hp goals with power up to 9000rpm. im very close to running. but NA or turbo doesnt matter. the heads would be identical for that operating range.

You're talking about custom high-lift cams, 5-angle valvejobs, knife-edged and balanced crankshafts, and the ~$500 retail conversion to SUB is going to put you over budget?

:hustler:

Projects like the one you are talking about do not get built on budgets. From all the parts and such you just listed, I'd estimate the price tag to be somewhere north of $10k, probably closer to $13k depending on who's doing all the work. The adhesion to the hydraulic lifters is a bit confusing.

I'm sticking to the HLA because this is still going to be somewhat of a DD until something else goes into it. If something goes wrong with the SUB assembly it's a PITA to correct, unlike the HLA. I'm not going to knife-edge the crank anymore because it's not ideal on an engine that I don't plan on rebuilding that frequently. This project is on a budget as a whole, not just the engine. To convert to SUB where I am isn't exactly 500 bucks. The dealers in Canada like to fist their customers in every orifice.

ctdrftna
I've took other members' advice on the cam situation and I'm getting one of the local race shops to build my head. I have all the parts for the bottom end but I'm having a bitch of a time finding a forged crank for this car. Other than that everything's forged.

Yeah, among us here on the forum we've had literally hundreds of bent cranks.

That's what's prompted me to do this. I built a half-assed bottom end and you should see how much my pulley wobbles. :facepalm:

I think that was written in sarcasm font.

You don't really need to worry about the crank, although an ATI damper would be a good investment.

If you are getting into the unexplored territory where the crank is an issue you should be building something different, like an FE3, anyways.

fanboi

our cranks are forged from the factory. maybe your looking for a billet crank. the diffrence being our cranks are pounded into shape, and something like a moldex crank is machined from a solid peice. it sounds to me like your in a bit over your head. i would stick to some pistons and rods and a nice refresh on the head with maybe some mild port work and good valve job. make your self something reliable. and forget trying to extract performance from every nook. i think if you want NA performance your in the wrong car. our heads are no where near a stock honda head, your not gonna make 200 whp out of a 1.6

NA = Bad

Turbo = Good.