ITT, I ask silly questions about building my VVT motor
 

So, I stumbled upon a decent looking VVT motor with ~60k miles. Came with crank sensor, '99 fuel rail, coils and the coveted squaretop intake (of which I already had one :party:).

Before this, I already got a '99 head, '01 intake with throttlebody, EGR and IAC complete with pigtails. There's a '94 shortblock completely disassembled laying around somewhere too.

Other parts already gathered are 425cc FIC EV14 injectors, supertech springs w/ retainers and the 949 superdamper.

Plan is to have bulletproof ~170 HP N/A motor for a 90% trackcar. I am not limited by power/weight/modification regulations to go on track. For the coming future, I will not go W2W racing and this is purely built for trackfun.

Questions now ensue:

Do I re-use the oem 10.5 CR VVT pistons (maybe coated)? If not, I can go crazy and do some supertechs in whatever bore and CR.

Do I need the BE oilpump? Plan to rev to 8k+ (and make power there) and already have the 949 damper.

Rods are coming too, together with ARP hardware for both rods and head. That should be it for the bottom end.

Now, for the head. I have supertech springs. Plan to add 949 shim-under-bucket lifters and have the whole thing ported etc. (not by me). Will this be enough to deal with the apparent VVT harmonics that rape valveseats at 7k+ RPM?

All of this will be controlled by an MS3X from reverant.

Also needs a new clutch, timing belt, seals and other small stuff that I can't think of right now.


Picture slightly related.

If it's not a JDM VVT it's 10:1 CR pistons.

I hope that the "harmonics" is just something that makes the OEM springs a bit too soft on the #1 intake valves (if so harder springs is one way to "solve" it).
My head that is still waiting for me to start it up have the stiffer ST duals now (my builders choice after having all ST setups to choose from).
ST singles should be a big upgrade from OEM for a stock intake cam. SUBs is a vise choice anyway to not spit shims.
If you go with ST longer valves (34mm intakes balances the flow somewhat for N/A), be aware that the lash caps will be very thin with OEM 36mm base circle.

Grinding the cam to a 33mm base will enable a bit more cam (blanks are rare) and makes the lash and spring pressure setup easier.

Make sure that the injector/coil harness is setup to do what you want. The connector at the front of the engine is identical in form, but not in function between the 98/00 and VVT.

Not too sure about the rest ( I know little about valvetrain upgrades ) but I can tell you with certainty that a be oil pump is a very good idea for your goals

I figured as much for the oil pump. Now to decide on street/strip/track version.

I didn't plan on oversized valves. The amount of boring needed to unshroud them properly would probably leave me with paperthin cylinderwalls. Unless I absolutely need them, I'd rather not. This also saves me the choice of stainless vs. inconel and all the fancy finishing options. Not the mention the increased stem length that will no doubt throw another wrench in the gears.

The VVT engine sitting in my car built by trackspeed has stock cams, stock lifters, and supertech springs and I was told it can rev to 8500. And it will on with april 7th if the course is that fast. Or friday the 19th of April unless I fail to get the turbo setup together in time or cant get on the dyno.

I'll probably place a big order at 949 soon enough. Still a little undecided on pistons. The 10.5:1 Wisecos or the 11.0:1 Supertechs, both in 84mm.

The rest would be rods, SUB lifters, timing belt, ARP head- and main studs, valve seals etc.

Then all I'd need is an oil pump (willing to trade BE pump for squaretop!!!:party:) and some random seals, small parts and oil cooler stuffs.

Neither, wait for 949 to start selling their spec piston. Wiseco is a noise cylinder wall eater, ST is a shitty shape. You want something that doesn't exist yet.

If it was me I'd do the supertechs, more compression is moar better and they shouldn't have the piston slap that the wisecos could have. Just need to do some hand work on the piston to clean it up before you install it.

1st time I hear of Wisecos being bad. Any data to prove this claim?

As for the supertechs, I believe it was Jason that may have tested and confirmed that they make the 01+ vvt engine "interference" due to not deep enough valve relief cuts or something like that.

I take comfort in having a non-interference engine, and would not want to change that.

I believe Emilio and others were discussing this "new" piston Hustley is talking about. I hope it comes out soon and isn't too spendy.

Does anybody have the P/N for the 10.5:1 Japanese pistons?

I'm wondering if they're available on Mazdaspeed.

Cold-start any car with 2618 metal and see what I'm talking about.
I know people who've bent valves on stock engines, I bent valves on 8.6:1 Supertechs, I know of people who've bent valves on 10:1 OEM pistons.
I'd probably buy whatever 949 makes, but I'm not spending any money any time soon.

Hand finished/fixed Supertechs is a pretty good idea and I was going to do that until I got tired of caring and "just wanted to go to the track" so I went OEM VVT.

- I have, and it was barely noticeable even on a very cold morning. Wasn't a miata though, that's why I'm asking.

- Yeah, but you're also one of the 1337 few that managed to blow up a built n/a motor too:giggle:

- That was an interesting discussion, and you guys are onto something there. I mean if one can get a 400 set of st's, and hog em down to acceptable clearance for free, and without side effects, that's the way to go vs the insanely priced 700-800 fm specials.

Don't worry about interference in general (i.e. no belt, max lift at TDC etc), worry about contact within the VVT adjustment range (I have contact beyond 35 degrees now).

The ST 11:1 don't have material to deepen the valve reliefs, the mod to make it to smooth all the knife sharp edges.

Nicer pistons would be in the next bottom end (there will always be a next one). Total custom is usually 50-100% more than OTS, so whatever Emilio&co make available it will be worth it (for the purpose it's designed for).

The price on parts of course adds up, but the price/value of the whole build is so much higher that $300 difference on pistons is close to noise.
For me the ST 11:1 was the available High CR choice to have something to start with.
Build #2, #3, #4 etc will benefit from the accumulated knowledge (that would probably take 10-15 years with my pace :))
A custom skeleton piston with 12:1 CR would be nice, maybe...

Maybe if we had a Honda head. Our cars need so much spark angle to make power since the head doesn't move air that I'd rather stay with a lower comp ratio and run pump-gas.

I completely agree with you on both counts, but you gotta draw the line somewhere. At a certain point you end up with a 10k engine and another 10k in drivetrain and turbo components, and wonder if you shoulda just started with a much newer, modern, and more efficient engine that would put out 700+hp for about the same amount of money.

I know, coolstorybro.jpg lol
Just my .02

*edit: +1 to the 1st part of what hustler said. -1 to the 2nd. high comp+e85 FTW:party:

What who where? How can you crush my dreams with any talk of corruption and slapping? I was confident that these were a very very strong piston with a bit more growth at temperature that other alloys. Is the minor warm up slap really going to cause more skirt wear as it "rattles around like a BB in a paint can" ?

Maybe the machinist had a bad bore for some Wiseco users out there, who knows.

I have been gathering parts for my VVT build and I have Wiseco's in the 83.5mm / 8.5:1 flavor. They are all snug at home happy in the knowledge that they are a great piston for my needs. Then I start to hear rumors about their unfaithfullness.
18psi - you havent had any issues with yours?

Anyone else care to comment either way. I'll be boosted and I do a decent warm up before I use "all of it" so I'm hoping to have good long life with this combo, but now you've got me thinking and 2nd guessing. Once I confidently buy an item I like to think that the thinkin's over and I can move on to the next part.

Ive had good results with CP and Wiseco, but again that wasn't on a BP so I really can't speak for them. I wouldn't imagine that matters much, but who knows.

Have fun listening to the clank clank clank clank in warm-up. I just don't care for it and none of us are making enough power to need the stronger metal.

Wiseco motors sound legitimately broken when they're cold.

+1 my car sounds like shit.