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Thread: VVT cams

  1. #1
    4,000 rpm - entering the fun zone RustRat's Avatar
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    VVT cams

    Sooo, once again, I seek advice from the wise elders of MR (I'm looking at you KFJ).

    I had a conversation today and this guy who tunes megasquirts somehow convinced me to build a high revving all motor itb VVT engine.

    First part of the question, what am I going ti need to achieve this? I'd prefer to have a stock bottom end if possible.

    •Billet-gear oil pump
    •Harmonic damper (ATI or Supermiata)
    •Camshafts and under shim buckets lifters
    •Valve springs (doubles?)
    •Titanium retainers
    •Head skimming, porting and polishing

    What camshafts do you suggest? Make? Duration/lift?

    What more do I need?




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    Last edited by RustRat; 10-17-2016 at 03:43 PM.

  2. #2
    4,000 rpm - entering the fun zone Hyper's Avatar
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    That's a lot of money on parts. You are missing Under Shim Bucket lifters on your parts list. I went with Tomei Camshafts from 949 Racing. I don't think there are many avaialble options for the VVT motors.

  3. #3
    2,000 rpm - light wheelspin, no bog here!
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    You're talking about a $6-8k pile of parts there. VVT is for midrange. Is that where you want your big cam, IRTB engine to make power? For a revver, pass on VVT, IMO.
    Just another cracka azz cracka with an Old Beat up '97

  4. #4
    4,000 rpm - entering the fun zone RustRat's Avatar
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    There's also Maruha's VVT camshafts, but they have exactly the same specs, and I think I've read somewhere they are just rebranded TOMEIs, so yeah, pretty much the same.

    When I said "under-shims" I meant under shim bucket lifters.

    So I am not missing any major component?


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  5. #5
    4,000 rpm - entering the fun zone RustRat's Avatar
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    Quote Originally Posted by Stealth97 View Post
    You're talking about a $6-8k pile of parts there. VVT is for midrange. Is that where you want your big cam, IRTB engine to make power? For a revver, pass on VVT, IMO.
    Since I already have the original 1.6 engine, and I bought the VVT engine recently, I'd prefer ti go the VVT route. And 1.8 engines are not so common where I live.

    6-8K? Wow. I was planning for the engine to cost me about 3-3.5K euros installed.


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    4,000 rpm - entering the fun zone Slampen's Avatar
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    What about a K-swap?

  7. #7
    4,000 rpm - entering the fun zone RustRat's Avatar
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    I'd rather stay in a miata engine, or I might run into trouble with the law. Plus it would cost a fortune to ship that thing to Greece.


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  8. #8
    4,000 rpm - entering the fun zone Slampen's Avatar
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    Quote Originally Posted by RustRat View Post
    I'd rather stay in a miata engine, or I might run into trouble with the law.
    Didn't know law was a problem in Greece.

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  10. #9
    3,000 rpm - starting to feel the power freedomgli's Avatar
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    You're getting perilously close to dangerous waters my friend! Better put your credit card in a block of ice while you think about this plan for a while.

    Your dreams sound fun but require a big budget and a lot of skill to achieve followed by a lot more upkeep. ITBs are great fun at any engine rotational speed as the smaller throttled volume makes the engine much more "responsive" and the larger overall throttle area means the engine can breath in that much easier without hurting intake velocity as much as a single throttle of comparable area (provided you have all the necessary supporting modifications). The higher you rev any properly built BP motor the more power it can theoretically make. This is why all the SCCA EP/GT3/GTL motors rev really high!

    Building the valvetrain to tolerate higher rpm operation is vital. However, revving higher than the factory limit with a stock bottom end means you're just trading high rpm HP for dramatically shorter engine life span. Boundary Engineering oil pump and ATI Super Damper are good investments to make. But even if you build the entire motor using top shelf aftermarket parts (crank, rods, pistons, valvetrain) and have it machined and assembled by an expert BP engine builder you still end up running into limits with piston speed and engine durability at higher rpms. So you must very carefully think about how much power you want from your Mazda motor, high you need to rev to get there and how long you want your engine to last. Getting 150-175rwhp is pretty straightforward. I'm afraid much anything beyond that is going to be a case of robbing Peter to pay Paul.

    Remember, it's not just a collection of parts that will get you there. It's the balance of everything working together.

    How to Make NA Horsepower - By Emilio of 949 racing

    Engine building ideas - By Emilio of 949 racing

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  12. #10
    4,000 rpm - entering the fun zone RustRat's Avatar
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    Quote Originally Posted by freedomgli View Post
    You're getting perilously close to dangerous waters my friend! Better put your credit card in a block of ice while you think about this plan for a while.

    Your dreams sound fun but require a big budget and a lot of skill to achieve followed by a lot more upkeep. ITBs are great fun at any engine rotational speed as the smaller throttled volume makes the engine much more "responsive" and the larger overall throttle area means the engine can breath in that much easier without hurting intake velocity as much as a single throttle of comparable area (provided you have all the necessary supporting modifications). The higher you rev any properly built BP motor the more power it can theoretically make. This is why all the SCCA EP/GT3/GTL motors rev really high!

    Building the valvetrain to tolerate higher rpm operation is vital. However, revving higher than the factory limit with a stock bottom end means you're just trading high rpm HP for dramatically shorter engine life span. Boundary Engineering oil pump and ATI Super Damper are good investments to make. But even if you build the entire motor using top shelf aftermarket parts (crank, rods, pistons, valvetrain) and have it machined and assembled by an expert BP engine builder you still end up running into limits with piston speed and engine durability at higher rpms. So you must very carefully think about how much power you want from your Mazda motor, high you need to rev to get there and how long you want your engine to last. Getting 150-175rwhp is pretty straightforward. I'm afraid much anything beyond that is going to be a case of robbing Peter to pay Paul.

    Remember, it's not just a collection of parts that will get you there. It's the balance of everything working together.

    How to Make NA Horsepower - By Emilio of 949 racing

    Engine building ideas - By Emilio of 949 racing
    Thank you for the extremely helpful post. I have to say that instead of discouraging me, it convinced me chase it even more now.

    I would be super happy if I could see 170whp, but more realistically I would be satisfied with ~165. I don't plan to rev it more than 8000rpm, probably around 7500-7800 would be better.

    Do you think this could lead to a catastrophic failure of the bottom end? One of my inspirations is Quinn's NB build, probably you have heard of his car, somewhere. He has done almost the same.


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  13. #11
    4,000 rpm - entering the fun zone Hyper's Avatar
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    get the Under Shim Bucket Lifters. If motorcycles can rev past 10k with these lifters you should be able too!!!!!!

  14. #12
    3,000 rpm - starting to feel the power freedomgli's Avatar
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    Here's another good post to read: Cost Effective Break Point - By Emilio of 949 racing

    Quote Originally Posted by RustRat View Post
    I would be super happy if I could see 170whp, but more realistically I would be satisfied with ~165. I don't plan to rev it more than 8000rpm, probably around 7500-7800 would be better.
    There is a recipe to follow to achieve this. Look at what emilio700 and Quinn have done, especially Quinn's first iteration before he went extreme with the head shave. It is possible with stock bottom end and lots of headwork (cams, sub lifters, valve springs, larger valves, porting, shaving to bump compression ratio), standalone ECU, the right exhaust system, and all the supporting reliability mods (coolant reroute, ATI damper, billet oil pump gears, oil cooler). Take any of these things away and you will be closer to the limit of reliability and/or further away from your power goal.

    You might have to go up to 7500rpm but I'd be careful. At that point you will have shorter engine life. It's hard to predict absolute life span as there are so many usage factors that play a big role but you could probably get many dozens of track days and many thousands of road miles out of it if you don't abuse it.

    Sorry I don't have VVT cam recommendations for you to follow and without knowing all the details of your head including flow-bench numbers after machining it's hard to say with certainty what the best cam profile will be. But it's hard to go wrong with a Maruha F-cam.

    Quote Originally Posted by RustRat View Post
    Do you think this could lead to a catastrophic failure of the bottom end?
    Yes, it is still possible. When pushing the limits there is no guarantee of absolute reliability. Engine lifespan decreases exponentially with engine rpm increase.

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  16. #13
    4,000 rpm - entering the fun zone RustRat's Avatar
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    Quote Originally Posted by Hyper View Post
    get the Under Shim Bucket Lifters. If motorcycles can rev past 10k with these lifters you should be able too!!!!!!
    Due to language differences I don't get if this is sarcasm, mocking me for using a term wrong, or just a joke. Sorry in any case, I can't respond.


    Quote Originally Posted by freedomgli View Post
    Here's another good post to read: Cost Effective Break Point - By Emilio of 949 racing

    ...
    Once again, great information. I'm leaning towards doing the cylinder head and leaving the bottom end almost untouched, until it dies. No rods, nothing. Then I'll see. I generally take care of my cars, and I don't abuse them.


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  17. #14
    4,000 rpm - entering the fun zone Hyper's Avatar
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    What sarcam? I don't understand..

    You are spending a fortune on engine parts and I am suggesting you get the under shim bucket lifters for the third time. The last thing you want is for the oem bucket lifter to spit out a shim and destroy your expensive cylinder head when you Rev the car past 7k

    Good luck

  18. #15
    4,000 rpm - entering the fun zone RustRat's Avatar
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    Quote Originally Posted by Hyper View Post
    What sarcam? I don't understand..

    You are spending a fortune on engine parts and I am suggesting you get the under shim bucket lifters for the third time. The last thing you want is for the oem bucket lifter to spit out a shim and destroy your expensive cylinder head when you Rev the car past 7k

    Good luck
    Oh, ok then. Thanks. Sorry about that, but I genuinely didn't understand your comment.

    Yeah, they have been added to the list, and after reading the posts above, I am thinking also about oversize valves and forged rods.

    I have a lot of reading to do.


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