Built 1.8L Options: 99-00 Vs. '01+ VVT

[HarryB]

Well, power in NA form comes from 3 areas; higher CR, higher revs, better engine breathing.

The 1st one is pretty straightforward; however one needs to pay attention in differences between static and dynamic CR.

Higher revving is an interesting topic. There's a limit imposed by the physical design of the engine, including choices in the head department (breathing, valve floating issues). Of course, the lightest the better (as long as everything is properly balanced), because the inertia and thus the loads in the reciprocating masses will be less. Faster throttle response is a bonus. However; higher revs means more friction, which steals power. And there's a point of diminishing returns. That being said, pistons make sense if lighter for a high-revving NA engine. I would agree on alloy of choice, especially in a car that gets driven often. Please keep in mind that pistons and rods should be designed differently between NA and boosted applications. Tensile strength is much more relevant than buckling to an NA rod.

Engine breathing... well in general more lift does make more power, but more lift with similar duration means more aggressive cam profile, thus higher valve acceleration. When combined with high RPMs, your valvetrain would have a hard time coping. At the same time, increased redline calls for more duration. One should take into account air mass inertia and scavenging phenomena when selecting cam profiles. And yes, VVT is always a benefit.

[— kung fu jesus —]

Preparig something very similar, and opted for the 01-04 VVT engine, mainly for the higher compression ratio, higher flow oil pump and, well, I got it cheap.

I have already taken it apart, and started rebuilding it. Everything that follows is my personal opinion, from sources I have read and I do not push anyone to follow what I do.

Slightly Ported and Polished head
Shaved head (I haven’t decided on the amount yet, aiming for a CR of 11-11.5:1)
3 angle valve job
Supertech valve springs and retainers
278 cams from an english company I can’t remember its name now.
Jenvey ITBs and 1.8 adapter
RS*R 4-2-1 header
That’s for the head.

About the block now:
Stock 01-04 pistons
Ebay rods (some of them are really good quality, and are good enough for my needs)
King Racing or ACL bearings
The usual ARP hardware everywhere
Billet oil pump gear in the stock oil pump
ATi Damper
9-10lbs flywheel
And balancing of the whole rotating assembly.

My aim is a revlimiter of 7.8-8K RPM.


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That's a solid goal and I like the approach.

So, if the 01 block has the 10:1 pistons and you want to reach 11:1 through a head shave, that's about .040". I believe it's doable, but you might be bumping into the valve should the timing belt break. General ROT is 1/4 point compression bump per .010" shave. Reaching 11.5 seems like a stretch, depends on your level of comfort. I would also want to know how much the rods stretch at the increased RPMs to factor that in too.

I bought a "tuning package" by a U.K. company called BLiNKMotorsport, I did have to travel the car a distance to fit it though. They shaved, ported and polished the cylinder head for a pretty decent price (as well as other fancy things as part of the package), but they won't/can't tell me how much they've shaved off or tell me what the compression ratio now is, without a compression test is guess work.

Short answer?? Since you've not messed with the CR yet I'd say forged pistons are the way to go, you know exactly what CR you're running (and they're heat treated/coated in fancy shiz to make them last longer :fab). You can install forged rods whilst you're in there too, or vice-versa. New pistons give you the option to up the displacement too, you can get 90% of the way to 2.0L with fat pistons alone.

There's always a debate on alloy differences, but I do believe there is something in having a closer wall clearance than people would have you believe. If you're never gonna boost it, 4032 all the way. Emilio (949Racing for those who don't know) knows his stuff and builds that sh*t to last

I would love to see a Stroker build happen ere though *hint hint hint hint*

There's a bit to unpack here but here are some key points...

I would be very pissed off if I paid a company money to do headwork and they didn't give me specs of their job. You should be dubious of the results.

Emilio builds his engines for specific purpose and goals, so realize there are longevity tradeoffs for certain enhancements. A race engine built to stay between 5-8k Rpms will make power, but it isn't expected to last long (hours versus miles). A street engine built to rev to 8k that spends the majority of it's time at 1000-5000 rpms, with occasional peaks to 8k, there's a tradeoff. If the engine sees peak power later, and is modified to do so where numbers are lower at the spectrum it spends most of its time, where's the advantage?

I defer to Harry's comments on the pistons. The stroker build was already done:

http://mazdaroadster.net/showthread....-Stroker-build

http://mazdaroadster.net/showthread....777#post137777

$26k, MTYCAP.

Well, power in NA form comes from 3 areas; higher CR, higher revs, better engine breathing.

The 1st one is pretty straightforward; however one needs to pay attention in differences between static and dynamic CR.

Higher revving is an interesting topic. There's a limit imposed by the physical design of the engine, including choices in the head department (breathing, valve floating issues). Of course, the lightest the better (as long as everything is properly balanced), because the inertia and thus the loads in the reciprocating masses will be less. Faster throttle response is a bonus. However; higher revs means more friction, which steals power. And there's a point of diminishing returns. That being said, pistons make sense if lighter for a high-revving NA engine. I would agree on alloy of choice, especially in a car that gets driven often. Please keep in mind that pistons and rods should be designed differently between NA and boosted applications. Tensile strength is much more relevant than buckling to an NA rod.

Engine breathing... well in general more lift does make more power, but more lift with similar duration means more aggressive cam profile, thus higher valve acceleration. When combined with high RPMs, your valvetrain would have a hard time coping. At the same time, increased redline calls for more duration. One should take into account air mass inertia and scavenging phenomena when selecting cam profiles. And yes, VVT is always a benefit.

Harry is wise.

[Hyper]

The only thing I will get from the 01-05 VVT block is the cylinder head valve cover components and oil pan with corresponding main bearing support plate.

Then build a high compression engine with a 94.5-95 block or Mazdaspeed block