how do YOU rev to 9K RPM?????

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09-13-2010, 02:41 PM
Armond30

how do YOU rev to 9K RPM?????

I am asking as many turbo 6g72 people this as I can, and I am quickly running out of ideas. As some of you know, I got my car put back together again with a new crank, rods machined to OEM diameter at torque, and stock bearings. I also have a crank scraper and windage tray. I am also running a Greddy 13 row oil cooler (same design as stock, just bigger), and twin CM 6.5" oil filters. (I am Racer_X from 3si btw. I don't post much, but rest assured, basic questions of "what about your valvetrain?" and "why do you need to rev so high, that's dumb?" are a non issue.). Teh car has DR stage 3 heads with high strength valve springs, upgraided lifters, blah blah blah. valves and heads and stuff are good. Car is running twin 3076 wheels. blows lots of air.......past 5K. That's beside the point.

long ago.....I was able to rev the car to 9K All motor (long story that will just waste time), but the revving slowly took it's toll on the bearings and as soon as I put power to it (installed the turbos), smashed a rod bearing or two. I firgured it was a machining problem with the rods so I had the rods reconditioned at torque (proper rod bolt stretch), and bought a new crankshaft and set it up as posted above. I was then able to rev the car to 9K without any apparent issues at first. rev to 7 ALL DAY LONG obviously. I don't drive the car much, but I figured the oil pressure was good (tool steel oil pump gears, 20 to 25 psi oil pressure at idle, 90-95 psi oil pressure max), got no signs of knock (banging around) on the knock meter, so it's all good. I must have tacked it all the way up (8500+) about 20 times or so. Well, last night, I decide to iron in my A/F ratio on the top end with the Emanage Ultimate (it works fine. not the issure), so I set the boost controller to wastegagte pressure (12 lbs), and I tack it up to 9000 RPM to verify the fuel map is correct for 7-9K. made a quick adjustment to it, and all seemed to be well. Then I drove down the expressway a bit to let the engine cool (temps were at 95C). when they got down to about 78C, I decided to get the timing sorted as I was taking out 1 degree of timing at 4K and ramping up to 6 degrees at 9. I zeroed it out, and stepped on it a bit, and noticed that just accelerating around 4K resulted in 7 counts of knock (VERY awkward, and tells me things are hitting things that they shouldn't). I say, well, I will reset the logger, and give it a go. as long as it doesn't hit 10counts of knock, I will run it. Well, ran it up to about 8500 or so and it hit 10 counts. I dropped it in neutral, and Oil pressure hit 0 (bright blue light in my face. I immediately pulled off the road and shut it down (as I heard the knocking sounds at the same time). Started it again to verify. Rod knock, Oil pressure SUBSTANTIALLY low (means filters almost 100% clogged (both of them)) and smashed rod bearing(s). I haven't taken it apart yet, but this appears to be 100% RPM induced damage at this point

I say all that to say this......if YOU are running 9K rpm, or KNOW someone who is (ray, Nelson, IPO, Matt, whoever....) HOW ARE YOU OR THEY DOING IT?!?!?!?!?!?!?!?!?!?!?!?!?!? The only thing I can think of left is to remove my windage tray and crank scraper, but I am doubtfull that will change the end result positively. It looks like >8K + Boost = DEATH. I don't understand or buy this theory, but it's hard to fight the obvious. The crank was balanced with my piston and rod assemblies, the rods were machined to spec, the crank was BRAND NEW, and the bearings were STOCK...........Crank pulley is STOCK. Timing belt is STOCK........HOW DO YOU REV TO 9K WITHOUT SLINGING THINGS APART?!?!?!?!?!?!?!?!?!

PLEASE HELP ME!!!
09-13-2010, 02:52 PM
Greg E

Did your oil pump fall apart? Rumor has it they're not up to par anymore.
09-13-2010, 04:11 PM
Armond30

No, the oil pump is still functionally in tact. I have upgraided oil pump rotors installed.
09-13-2010, 04:55 PM
JasonY

Ray would be the person to ask. I dont think Chris turns that high and Chris is actually the only one still using the 72 crank which may have something to do with your problem since with big power/rpm's it may be getting a little flexible wiping out bearings in the process.

Jason
09-16-2010, 01:57 PM
skater334

Matt (and once Nelson is done w/ his new build) runs all high-rev capable parts (valve springs, dogbox tranny, forged crank, etc). The reason being that the bearing are crapping out on ya is the fact their only only meant to handle a certain RPM, after that they reach the breaking point which in-turn causes failure. You'd have to run ALL forged internals, and pray they hold. How much boost and what kind of turbos would you be running and how often after each race do you have your motor rebuilt?
09-16-2010, 03:50 PM
TooFast4Radar

Dirty Dave aka Turbo Tension was revving to 9k RPMs and ended up rebuilding his new OEM shortblock after not many miles. The bearings were toast and I don't think he really knew what caused it. Like you he had Stage 3 heads and everything was properly built.
09-17-2010, 11:17 PM
Boostaddict

Quote:

Originally Posted by skater334

Matt (and once Nelson is done w/ his new build) runs all high-rev capable parts (valve springs, dogbox tranny, forged crank, etc). The reason being that the bearing are crapping out on ya is the fact their only only meant to handle a certain RPM, after that they reach the breaking point which in-turn causes failure. You'd have to run ALL forged internals, and pray they hold. How much boost and what kind of turbos would you be running and how often after each race do you have your motor rebuilt?

Wow that was technical.
09-18-2010, 08:12 PM
Flamer

Always thought it was due to our cranks oil passage routes?
09-20-2010, 02:09 PM
Armond30

Quote:

Originally Posted by skater334

Matt (and once Nelson is done w/ his new build) runs all high-rev capable parts (valve springs, dogbox tranny, forged crank, etc). The reason being that the bearing are crapping out on ya is the fact their only only meant to handle a certain RPM, after that they reach the breaking point which in-turn causes failure. You'd have to run ALL forged internals, and pray they hold. How much boost and what kind of turbos would you be running and how often after each race do you have your motor rebuilt?

Hmmm.. thank you for your responce, however i would probably humbly disagree that bearing life is primarily dependant on rpm. There are a LOT of factors involved. I think i finally understand why high rpm is leading to continued failure. One hint is i think Nelson will be one of the few people to overcome this restriction.
09-20-2010, 02:58 PM
skater334

Quote:

Originally Posted by Armond30

Hmmm.. thank you for your responce, however i would probably humbly disagree that bearing life is primarily dependant on rpm. There are a LOT of factors involved. I think i finally understand why high rpm is leading to continued failure. One hint is i think Nelson will be one of the few people to overcome this restriction.

Matt has too, he offered to sell me his block from the Stealth and said they when they rebuilt it the bearings were just as good as ever and they beat the piss out of it.
11-13-2010, 06:37 AM
Tigchamp

Hey Guys,
Where can I get the uprated pump gears from. BTW Ben from Eurospec in the UK has run his Drag 3000GT @ 8600 for two seasons.
Jeff
11-13-2010, 04:12 PM
TurboSinceBirth

Boostaddict had some but I'm not sure if Wayne has anymore in stock. Itallo also made some of the gears but I don't know if he has any left either. I'm sure someone will need to make a batch. I have Itallo's billet oil pump gear but either would work well. :)
11-13-2010, 06:16 PM
J_Parker

I suppose I'll chime in :p I'm not too savvy on all this, but just from a thought of simplicity here... I'm thinking you guys running in the 9k range RPM's are having prolems with it due to too large of bearing gaps and improperly balanced rotational masses.

If you're running a high RPM setup, that's going to give the cranks flex more intertia if the crank/bearing spacing is large enough, hence beating the shit out of the bearing. Afterall our pistons at an RMP of 9K are moving at ~10,000 feet per minute, the end of the stroke is the stopping force of the that piston. If it's imprperly balanced the piston offsetting the stroke of the oposite is going to either be too heavy or too light, think about if you were to weld a quarter onto one of your rods, that would be an exteme case of a shitty balance, but it gives you a better idea of what I'm trying to get at. (I can think about whats happening, but I suck at wording it)

I would suggest a hardened crank, a good balance and a very intolerable bearing clearance.