3.4L Motor Swap Underway!

[insite]

mikstew -

i really just moved one pin at the DME to control the varioram flap. i had the DME programmed to the RoW (euro spec) 3.4L program. that's really it. i used the actuator for the secondary air system (RoW eliminates need for it) to operate the varioram flap. i basically swapped the wire from the secondary air DME pin to the varioram DME pin.

as for the programming itself? you need to take proof of ownership to a dealer & have them print out your immobilization codes. you send your DME, along w/ the codes, to someone who can program it for you (tholyoak).

[insite]

i had the oil from the blown motor analyzed. interesting results available here:

http://986forum.com/forums/boxster-general-discussions/28121-interesting-oil-analysis-blown-motor-post241353.html#post241353

[MikenOH]

One of the guys on the Cayman board had a connecting rod bolt failure--due to an over rev--on a motor that had about 40K. 7300 rpm for 1/2 second--boom.

After the engine was torn down, IIRC, he mentioned that that there is a consensus that these connecting rod bolts will strech over time and that this is really one of the big weak links in the motor for people that do track time and tend to run the motors in in the upper rpm band. His take away was to keep rpm's down under 7K--more in the 6500 range-- since the power drops off above that anyway.

Any thought on this?

[insite]

1) i doubt if a 7300RPM over-rev would cause a rod bolt failure by itself. the rod bolts in the cayman motor are pretty much the same ones in my 3.4L 996 motor, which has a 7300RPM redline. it works out to less than 6% more force (than 7100RMP), which will be inside the design limits for the bolt. risk from over-rev is generally to the TOP END of the motor, not the bottom. the pistons go faster than the valves can retract & a collision occurs.

2) reducing the rev limit will DEFINITELY reduce fatigue and stress inside the motor. force on the rods & rod bolts increases with the SQUARE of RPM's, so the effects become a lot more pronounced as the revs go up. at 10000 RPM, the accelration at the piston is around 250,000 fps/s. at 5000 RPM, you're under 65,000. you've halved the RPM's, but cut the force by 4.

if you drop your observed rev limit from 7100 to, say, 6700, the max forces reduce by about 11%. over time, this can make a difference. personally, i wouldn't bother. as i stated earlier, the functional rev limit is really dictated by the valvetrain.

Originally Posted by MikenOH

One of the guys on the Cayman board had a connecting rod bolt failure--due to an over rev--on a motor that had about 40K. 7300 rpm for 1/2 second--boom.

After the engine was torn down, IIRC, he mentioned that that there is a consensus that these connecting rod bolts will strech over time and that this is really one of the big weak links in the motor for people that do track time and tend to run the motors in in the upper rpm band. His take away was to keep rpm's down under 7K--more in the 6500 range-- since the power drops off above that anyway.

Any thought on this?

[schoir]

Originally Posted by insite

i had the oil from the blown motor analyzed. interesting results available here:

http://986forum.com/forums/showthread.php?p=241353#post241353

What happened to the post with the wrong educated guess on the type of oil that was being analyzed? :dance:

Regards, Maurice.

[insite]

Originally Posted by schoir

What happened to the post with the wrong educated guess on the type of oil that was being analyzed?

still there; it's the last sentence in post #3

[schoir]

Originally Posted by insite

still there; it's the last sentence in post #3

Insite:

Thanks.

I was sure I remembered reading someone deducing from your oil analysis report that the oil you were using was most likely Royal Purple.

I must have been having a senior moment!

Regards, Maurice.

[insite]

ok, first track outing Monday. went pretty well, with a few lessons learned & some other observations.

first, WHEELSPIN. inside wheelspin is a big issue now. never was before. i will need to adjust my suspension to allow a bit more roll.

second, i am RUSTY! two years out of the cockpit took a toll! by the end of the day, i was turning some REASONABLE laps, but nothing i haven't beaten handily with the 2.5L. two my defense, i forgot to air up the tires before i aligned the car & it was toeing out under braking. that, coupled with the extra power, meant i was braking way too much. also, my tires are several years old & apparently hard as rocks.

third, HEAT!!! the 2.5L cooling system is NOT adequate for this motor in track conditions. it was only 84F out and after only about thirteen minutes full tilt, the car would heat up to 225F before i'd pit to let it cool. i was even shifting 300 revs shy of redline. i will be installing the center radiator, removing the AC condensers, replacing the supply lines to the motor with the 'S' version, and eventually, removing the AC compressor. i will also be adding some vents to the wheel wells to allow for better flow through the radiators.

all things considered, the car ran quite well. i was VERY nervous what with Byron's recent exploits......every little sound or weird smell produced visions of dollar signs dancing in my head. BTW, Byron borrowed a race car for the outing, which he did NOT blow up. thank god.

best TOD for me was 1:12:01 (best ever in the 2.5L was 1:11:11). i'll be back out there in may with a re-vamped cooling system. and hopefully some speed!

[Lobo1186]

sounds like maybe you need an LSD. or do you ahve one already?

[Gilles]

Originally Posted by insite

ok, first track outing Monday. went pretty well, with a few lessons learned & some other observations.

HEAT!!! the 2.5L cooling system is NOT adequate for this motor in track conditions. it was only 84F out and after only about thirteen minutes full tilt, the car would heat up to 225F before i'd pit to let it cool. i was even shifting 300 revs shy of redline. i will be installing the center radiator, removing the AC condensers, replacing the supply lines to the motor with the 'S' version, and eventually, removing the AC compressor. i will also be adding some vents to the wheel wells to allow for better flow through the radiators.

Insite;

I installed the center radiator from a tiptronic and it made all the difference in the world..! Suncoast sells the complete kit

However I noticed that your front bumper does not have the opening on the center for the radiator, would you be replacing the bumper with one that has the center hole or cutting one..?

I remember that I had to cut rectangular outlets at the bottom of the bumper to allow the hot air out (similar to the ones with an auto transmission).

.