Just curious were you running a stock or lightened flywheel ?

Im planning to run a stock flywheel with a FM clutch. With all the vibrations that are going on at the crank with 250whp using a light weight flywheel seems like a bad idea

 

FWIW I've been running 17psi-18psi (MBC) with a GT2560 on my stock 97 engine daily for a couple years. I do have minor oil consumption (.5L in 1500-2000km).

I only operate the car this way because I have a vvt head sitting there and intend to build a bottom end anyways.

YMMV

 

The flywheel side of the crank is held in place by the rest of the drive-train, worry about the oil-pump end instead.
Or are you planning to use 250+hp while free revving (or slipping the clutch massively)?

 

Yes I was using a lightened flywheel. Shouldn't of been why it blew up though it was balanced and I had the stock harmonic balancer.

 

Fwiw I was using the fidanza FW with 244hp 218Tq and it felt fine and never gave me a problem

 

how many miles at 244whp and with what kind of abuse ?

 

I have an ACT 13lb flywheel and it's great except if you like high load, low rpm driving. If you do your transmission will rattle, otherwise it allows for faster, smoother shifting. I've only had it for ~5000km.

Again, YMMV.

 

Paul actually sold his car and put that money into a business or something a few years back if I heard correctly.

There have been a few GT2560's on stock bottom ends making around 300hp reliably throughout the years. Saint_Foo was also pushing right around that much on his setup, and I know he beat the **** out of it. One thing is that just about every gt2560 making that sort of power is on an absurdflow setup.

 

So when it comes time that I start tuning the spark am I correct in my thinking that the way to tell if my timing is too far retarded would be

1. get an EGT probe and watch for high temps (which I havent really planned to use on my setup)

2. Watch the AFRs and see if they start going richer

 

egt and afr won't tell you if you reached mbt.
well, egt might but still I wouldn't trust that at all.
only way to know is to get on a dyno and keep advancing til it stops making power or knocks. or you can do the whole butt dyno/virtual dyno thing but not as accurate.

 

Under 4k Im not really going for MBT. Id like to keep torque down a little lower than most people making 240-250whp in an effort to keep from bending rods. I should beable to keep the torque down by retarding the timing. But dont want to go too low and cause issues

 

so stay in the range most have it at and don't sweat it

I just see no reason to get an egt sensor/gauge unless you just want to

not running boost control going straight off the wastegate is the best way

 

Resurrection.

Conservative tune, stock engine, '99. Concern is rods, just like this thread.

Can I run 200- 210 Ft-Lbs torque safely as low as 3500 RPM, if the mini-turbo can make it? Right now I'm hitting it at about 4000, same as Karter74 did.

 

You can run 200 ft lb at any rpm you want, but not 250.

We have done dozens of reliable 260rwhp cars making 220ftlb this way.

Dann

 

I use boost control to ramp in boost slowly with rpm, 10psi at 4k and ramp to 15 by 5,500 rpm. Never on a Dyno but runs mid 12's @108 which is enough to be solidly in the mid 2xx's

 

I would theorize that the RPM doesn't matter, but the ignition timing matters a great deal. Lots of ignition timing = tons of peak cylinder pressure. In order to get big torque from a turbo before the cams are in their sweet spot, people typically pile in the timing, which bends rods. Keep the timing soft and you can probably make 220wtq at 3000rpm on a stock motor if you want to.

 

Honestly, I've heard a compelling argument that you can run even more torque in the top end because the force is applied for a smaller period of time when rpm is highest. But I still stick with 220ftlb and make certain the timing is very soft in the 3000-4500rpm range.

Dann

 

It's a combo of both, less air and fuel in the cylinder sparked closer to MBT will make the same power as more air/fuel sparked later in the cycle. I like to spark the mix earlier in the cycle with a rich mixture, helps to dampen that cylinder pressure spike and keep an even pressure on the piston through out the cycle.

To your point timing is very important but it gets to be a lot easier to control with less boost pressure.

 

There is no time component when it comes to a force applied to a body, though. The force is applied, and the body can withstand it, or the body can't.

 

It certainly takes a period of time for force to bend something, and the combustion period is an extremely short time at 7500rpm. So without further knowledge, its a compelling idea for me, but I am not sure whether it is true or if the effect is significant enough to be relevant.

Dann