Got Head? RPM Question.
#1
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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.
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.
#4
^ 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
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
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^ 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
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
#7
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.
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.
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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.
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.
#12
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.
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.
#13
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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.
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.
#15
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.
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.
#19
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.
#20
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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.
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.
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.