OEM Cams
#17
TheMan is right he’s got all the info except valve sizes – at least I couldn’t find it. I know I wrote it down somewhere, but I can’t find it now.
1991cc
130 hp @6000
135 ft-lb @ 6000
83 x 92 mm
9.1:1 (fs-de) 10.2:1 (fs-ze)
I’m not looking to produce high rpms with a bore x stoke like that, but I do think the motor could be a good low end torquer for a 4cyl. About 7000 rpm would be tops. Mine’s seen a good bit over 7500 just to look for a rev limit, but in my short try I didn’t find it. Right now there’s surely no need to run that high as power drops like a stone. I heard somewhere that there is a fuel cut off that comes in after the ECU detects sustained high rpm operation, but that just don’t sound right.
Maybe someone can enlighten us on that subject and give us the valve sizes. Hey while we’re at it anybody know the valve spring compression rates? Chamber volume? Valve length?
I’m surpised that no one had any input on cam profile other than to suggest buying the factory cam. It may be JDM but it is still a factory cam. Thanks for the effort JasonC.
1991cc
130 hp @6000
135 ft-lb @ 6000
83 x 92 mm
9.1:1 (fs-de) 10.2:1 (fs-ze)
I’m not looking to produce high rpms with a bore x stoke like that, but I do think the motor could be a good low end torquer for a 4cyl. About 7000 rpm would be tops. Mine’s seen a good bit over 7500 just to look for a rev limit, but in my short try I didn’t find it. Right now there’s surely no need to run that high as power drops like a stone. I heard somewhere that there is a fuel cut off that comes in after the ECU detects sustained high rpm operation, but that just don’t sound right.
Maybe someone can enlighten us on that subject and give us the valve sizes. Hey while we’re at it anybody know the valve spring compression rates? Chamber volume? Valve length?
I’m surpised that no one had any input on cam profile other than to suggest buying the factory cam. It may be JDM but it is still a factory cam. Thanks for the effort JasonC.
#19
Originally posted by zeus
TheMan is right he’s got all the info except valve sizes – at least I couldn’t find it. I know I wrote it down somewhere, but I can’t find it now.
1991cc
130 hp @6000
135 ft-lb @ 6000
83 x 92 mm
9.1:1 (fs-de) 10.2:1 (fs-ze)
I’m not looking to produce high rpms with a bore x stoke like that, but I do think the motor could be a good low end torquer for a 4cyl. About 7000 rpm would be tops. Mine’s seen a good bit over 7500 just to look for a rev limit, but in my short try I didn’t find it. Right now there’s surely no need to run that high as power drops like a stone. I heard somewhere that there is a fuel cut off that comes in after the ECU detects sustained high rpm operation, but that just don’t sound right.
Maybe someone can enlighten us on that subject and give us the valve sizes. Hey while we’re at it anybody know the valve spring compression rates? Chamber volume? Valve length?
I’m surpised that no one had any input on cam profile other than to suggest buying the factory cam. It may be JDM but it is still a factory cam. Thanks for the effort JasonC.
TheMan is right he’s got all the info except valve sizes – at least I couldn’t find it. I know I wrote it down somewhere, but I can’t find it now.
1991cc
130 hp @6000
135 ft-lb @ 6000
83 x 92 mm
9.1:1 (fs-de) 10.2:1 (fs-ze)
I’m not looking to produce high rpms with a bore x stoke like that, but I do think the motor could be a good low end torquer for a 4cyl. About 7000 rpm would be tops. Mine’s seen a good bit over 7500 just to look for a rev limit, but in my short try I didn’t find it. Right now there’s surely no need to run that high as power drops like a stone. I heard somewhere that there is a fuel cut off that comes in after the ECU detects sustained high rpm operation, but that just don’t sound right.
Maybe someone can enlighten us on that subject and give us the valve sizes. Hey while we’re at it anybody know the valve spring compression rates? Chamber volume? Valve length?
I’m surpised that no one had any input on cam profile other than to suggest buying the factory cam. It may be JDM but it is still a factory cam. Thanks for the effort JasonC.
as an interesting side note, i have been looking into adjustable cam gears over the past week (see my other thread about that) and the BP motor in the miata likes some very weird profiles on the cams to produce good low end torque and better high end power.
#20
Originally posted by njaremka
but it seems to me that there just isn't a high number of very technical people on this board.
but it seems to me that there just isn't a high number of very technical people on this board.
as an interesting side note, i have been looking into adjustable cam gears over the past week (see my other thread about that) and the BP motor in the miata likes some very weird profiles on the cams to produce good low end torque and better high end power.
#22
Originally posted by Eric F
The adjustable gears would make it considerably easier and less time consuming due to not having to remove the timing belt each time you want to try a different setting.
The adjustable gears would make it considerably easier and less time consuming due to not having to remove the timing belt each time you want to try a different setting.
#25
Then we must get someone to make them! To tune the engine by adjusting cam timing requires a dyno. Dyno time isn't cheap, and adjusting cam timing by having to remove the belt is time consuming. This seems to mean multiple visits to a dyno to test results. Too expensive and inefficient for me. Unless someone has free access to a dyno, this doesn't seem very cost effective. What about the Speedvision World Challenge Touring Proteges? They must have some adjustability for tuning, maybe we could get the gears through AWR, Tri Point, or Sunbelt Performance?
Originally posted by jmauld
No doubt, plus the gears will allow for better adjustment resolution. BUT, if there are no gears....?
No doubt, plus the gears will allow for better adjustment resolution. BUT, if there are no gears....?
#26
Originally posted by Eric F
. What about the Speedvision World Challenge Touring Proteges? They must have some adjustability for tuning
. What about the Speedvision World Challenge Touring Proteges? They must have some adjustability for tuning
They probably have custom cams made, that already have the appropriate cam specs for max power.
#27
Custom ground cams is what started this thread in the first place. Adjustable pullys would be nice for dialing in just the right overlap though.
Soon as a good header option becomes available I'm getting the grinds, doing the head work and modding pullys if I have to. Just trying to get info now, but it looks like I may be the first that has the ***** to cut into it.
Soon as a good header option becomes available I'm getting the grinds, doing the head work and modding pullys if I have to. Just trying to get info now, but it looks like I may be the first that has the ***** to cut into it.
#28
What little bolts in the middle? We're talking about the stock camshaft gears, not adjustable, since there doesn't appear to be any available yet. The stock gear has slots that allow it to fit on the camshaft one way, you can't adjust the position of the stock gear on the cam. You could rotate the the cam and gears' position by moving it forward or back one position in relation to the timing belt, but that's time consuming, and not very accurate, which was my point. We need adjustable gears as another method of tuning the engines power band.
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