l_bader

Balancing the crank, flywheel and pressure plate as a single unit will smooth things out.

+1... But my engine is definitely "overbuilt".

Polish the crank unless you choose to knife-edge.

Clean up and port match the head. IMHO polishing the runners is counter-productive. I prefer to have the turbulence in the runners over the risk of boundary layer effects...

Keep in mind your turbo is nothing more than a force multiplier. The stronger and more efficient the foundation, the better gains you will see when you add the boost.

- L

Midtenn

iTrader: (15)

There is another factor that has be looked at with Bill's car, the amount of time spent above 7500rpm. I don't know many road racers that will lay on the limiter for multiple seconds. I drove a CSP at Nationals last year and there were multiple times I laid into the limiter for long periods of time. A few times I even short shifted just to "save the motor" after reading about Bill's problems. The owner of the CSP car I drove has since changed to a 5spd and 4.1 and dropped the limit down to save the motor (all though after 1.5 years of abuse, the motor is still healthy with no leak down issues).

JasonC SBB

Don't reuse hi-mileage rings. Put new rings and hone it.

Pat found out the hard way. See his thread on m.net.

JasonC SBB

I'm of two minds.

First possibility: Resonance in valvetrain *at* the ("fundamental") frequency it opens and closes at 7500 RPM; solution, stiffer or shimmed or dual springs, and/or lighter valvetrain parts (e.g. shim-under-bucket).

2nd possibility: Resonance in valvetrain at 2nd or 3rd harmonic meaning, a multiple of the frequency it's opening and closing at, at 7500 RPM. The amount of excitation at the 2nd, 3rd, or higher harmonics, is a function of the aggressiveness of the profiles.

When your valve starts to open, this sequence occurs:
1- first part of lobe comes in, to gently reduce the lash to zero
2- valve is accelerated open
3- valve is at maximum opening *velocity* - it's opening wider and wider, and halfway up the lobe
4- velocity may be maintained for a bit
5- lobe/spring begins decelerating valve - spring actually does the deceleration, and lobe/lifter interface unloads a bit
6- valve reaches peak opening, this is zero *velocity*, and peak deceleration
7- valve continues its deceleration so that it begins to close (deceleration is actually acceleration in the closing direction
8- valve reaches constant closing velocity, and it's closing more and more
9- lobe profile begins to decelerate valve to soften its landing on the seat
10- valve reaches some low-ish velocity before it contacts the seat

The problem with banging seats I believe starts with too much peak deceleration in steps 5 6 7, so that the lobe loses contact with the lifter. This is float.

This is like a ski or motocross jump. If the ground drops away at an acceleration greater than 1G, gravity (or the spring), can't accelerate the skier/rider/valve down fast enough to keep contact with the ground. And the landing will be hard if the bottom of the hill on the other side.

The lifter loses contact all the way until the point where it's supposed to be closed, so the valve isn't decelerated in order to land gently on the seat.

So you can see that the acceleratoin/decel peak numbers are proportional to RPM. There will be a point where these peak numbers exceed the spring's capability to accelerate the mass down.

There's also a more serious, complicating factor. The spring coils oscillate up and down, and if this frequency coincides with the RPM, the spring actually momentarily stops applying force to the valve, at the worst time.

There's a youtube vid of it...

Going back to the harmonics. If it's not the frequency directly from 7500 RPM, then it could be the harmonics (multiples) of this fundamental, which is a function of how sharp the accel and decel ramps are on the profile.

Thinking about it some more, it seems not very likely; but lower peak decelerations around peak lift I think would still help, and so would landing velocity. A higher rev limit requires a softer landing and reduced peak deceleration at the top of the lobe, for a given RPM, so that you can run at higher RPM.

I also suspect that the purported cause, the term "harmonic at 7500 rpm" is a misnomer, the problem is probably "resonance" at 7500 RPM. Again I think stiffer springs is the easiest solution. Resonance moves up as the square root of the increase in stiffness or reduction in mass.

e.g. 21% stiffer springs, will increase the resonant frequency by 10%

Reverant

iTrader: (10)

I wanted to say this, by I also wanted to avoid being the physics ****.

dgmorr

iTrader: (4)

Would 110k KM be considered high? I was planning to do just rods next off-season. I don't want to skip the minimum required steps, and I also don't want this to turn into a high end (dollar) build.

baron340

iTrader: (5)

If you pull the slugs out of the cylinders, you must hone and install new rings. The rings get microscopic peaks and valleys as do the cylinders during break in. If you take the pistons out, you will never get them exactly lined up and you will have bad compression. Can you install rod bearings without removing the slugs?

Savington

iTrader: (31)

100km is considered "high" IMO. If you remove the pistons and rings, you must hone and re-ring.

You can do rings, pistons, and all the machine work on a bottom end for under $2k including parts. Head refresh adds a bit of cost, assembly adds a bit more.

falcon

iTrader: (13)

100k KM is not really that much. It's 62,500 Miles. 100,000 Miles on the other hand is 160,000 KM and that is getting up there.

dgmorr, if you know how do a leak down and a compression test. That will tell you a lot about the health of the motor. If it's healthy, just keep it at or under 250whp until you decide to build a motor. Throw some M-Tuned rods in, bore/hone, polish crank, OP gears and pistons of your choice. Don't need to go too crazy. While the head is off, check the valve guides for stickiness or looseness and if you feel like it replace the valve oil seals.

Savington

iTrader: (31)

I said 100 kilometers, not 100,000 kilometers. The point was that if you are removing the pistons from their bores (which you are doing to install rods), you must hone and re-ring.

Valve seals are outrageously cheap, incredibly easy to replace, and you would be a fool to leave the old ones in place, ESPECIALLY if you have the head off the car.

I still want to know who told you that VVT oil pumps were stronger, BTW.

dgmorr

iTrader: (4)

Points taken, thanks for the info.

Rennkafer

iTrader: (3)

The downside to stiffer springs is at some point you start beating the **** out of the cam lobes instead of the seats. Cams and springs, like a lot of stuff in an engine are (or should be) designed as a system.

I agree with your suggestion to talk with Dema about it. I'd also maybe try to pick TurboTim's brains as well... Jesel makes some pretty cool valvetrain stuff.

falcon

iTrader: (13)

Gotcha. It looked like you said Miles.

falcon

iTrader: (13)

My valvetrain was chosen by Maruhas recommendations. They use the BP valve springs on pretty much all of their cams up to 8.5mm lift. Apparently the spring works out perfectly for cams around that lift and can rev 8k+ without float when used in conjunction with solid lifters. They were fairly cheap too which was nice. In addition I bought some MazComp SUB lifters and used supertech lash caps at $4/ea. And my cams were custom grinds costing around $400 and have supertech SS 1mm over valves. All in all my head aside from the port work was extremely cheap. I also replaced the guides, shims and seals.

miatamania

iTrader: (9)

"Stock" Motors. Factory parts only.

Landrew

iTrader: (2)

The above makes the Trackspeed Engine seem like such a deal.

My motor "went" on Monday. Not sure the details yet but sudden loss of power under boost, misfire, increasingly blue smoke until about 2km later is was a nice cloud and then stopped. Still cranks. Haven't touched it in 3 days except to see if the turbo seals went and oil got into the intake - which it didn't. Since the car and I are fighting I don't want to see if for a few days until I'm ready to talk nicely to it.

I keep debating dropping in a $1000 dollar used motor or rebuilding mine slowly or buying a Trackspeed built motor.

I've rebuilt single cylinder 2 stroke bikes, modern 4-stroke motocross bikes and ATV's 8 times. Including gearbox and bottom ends. Still I'm not that confident in rebuilding a 4cyl. car motor.
With my rebuilds I did everything except the re-bore of 2 motors (the rest were nikasil lined and in good tolerance) What does the shop have to do for me and what cost and what can I do all by myself? Do I absolutely need to know how to use Plastiguage for example or other new to me procedures?
Part of me wanting to do my own build is to get the experience and say I built my own engine!
If I had more income Trackspeeds engine would be bought today. I may just save up over the next 6 mos. for that gem anyways

Tips, thoughts ?

ps goals are about 300 +/-20 whp..

chokeasphyxia

iTrader: (8)

I kind of wish I'd gone with TSE engine.

shlammed

iTrader: (8)

landrew.... its just a (physically) bigger engine.

Set your rings proper, get proper clearances with proper machine work and it will be fine.

Landrew

iTrader: (2)

Singles have cranks on real bearings, and no rod bolts or main caps. Crank bearing on multi cylinder engines seem to be named odly to me, bushing seems for fitting, that's a whole new area for me.

Being from Canada what machine services and costs did you have to pay for and how much if you dont mind telling?

Are you still a 1.8 or 1.9L now, and how do you like the 2871 .86?

EO2K

iTrader: (37)

TSE is on my list if/when mine/I does/do something stupid. CA sales tax is gonna suck...