Blown motor after lsa and tune

[ZL1C7]

You might want to think about the possibility that you are losing the trans (slipping)and the LSA was just enough to push thru the weakest link. With this in mind your new motor would be at risk on the first hit. Maybe pull the trans pan for a piece of mind and a sniff the fluid check.

[Dwright]

Thanks for the insight, I will deffently have them look into this. It was flaring between third and fourth after the Tq was installed but later found the trans was 3 quarts low. Once the new shop I went to filled it seam to have fixed the issue. But I am definitely going to have it checked. The block should be here in a few days and the tear down will begin once it's on the lift I will look at the trans.

[Elite Engineering]

I started o read this thread thinking, "man this sucks", than I saw 8,000 RPM? There is no way to soin a LS engine much above 7,000 RPM before the valve train becomes so unstable that your lucky you did not drop all the valves.


Even a ProStock engine is limited to 10,000 RPM and there are $10's of thousands that go into the balance of every aspect of the rotating assembly alone much less the valvetrain. To go into more detail, the length of the valve stem and valve guides to be able to go above 7k RPM requires a billet cylinder head with so much meat allowing this aso the push rods are far shorter as well. The cam location is raised significantly from the LS location as well the accommodate this, and then the valves are a triple spring with inner dampener due to the amount of resonance and harmonics produced that have to be addressed. To correctly build a LS engine to turn 8k PM's I would imagine would approach $50k to be able to even survive reaching that high of spin, and all forged internals are not enough. The rev limiter is a tool to prevent catastrophic failure, and to raise it past 6,500-even 7,000 is asking for quick failure. These are not over head cam engines, these are still push rod technology that has been used for over 100 years!


A typical PS engine cost in excess of $100k to build. Please read this article to understand more of what I am sharing here. It is basically impossible to take a stock block, with stock cam location to safely spin to 8k RPM. The thickness of the push rods alone will not even fit a LS block, and lifters would have to be bores significantly larger and sleeved, spring open rates would need to be close to 800# (vs the few hundred for the average aftermarket cam available today, and today's cam lobe profiles would not allow it:


http://www.enginebuildermag.com/2011...ine-technology/


Your tuner should have NEVER even attempted this, and not knowing who it is, and with so many talented and knowledgable tuners out there I would say that was your biggest error, and it was costly. You should be enjoying your car today with the rev limiter set below 7k, but instead you have a pile of broken parts.


Wish you good luck in the future, but if you attempt this again, even with the best built LS based block as a platform, you will experience the same results trying to spin that high.

[Dwright]

The tuner stated he had the rev limiter set to 6200 rpm. I do not know how it hit that mark but it occurred between 3rd and 4th gear shift. It doesn't make since to me unless my trans slipped but I would I don't know if that would allow it to still go past the rev limit. The tuner is well known across the county for tuning just not ls motors, but he had a buddy from lingerphelter giving him a hand so I doubt it was the tune. I just want to make sure it doesn't happen again. I am considering a trans rebuild just to be sure. Idk if that would just be a waste of $ but don't want to deal with another blown motor.

[ZL1C7]

You guys keep jumping to conclusions to the tuner but no limiter can stop a free revving motor during acceleration like that. In addition, a motor that revs unloaded is WAY more likely to hurt parts than a loaded one. I had a big inch motor shear the flexplate bolts a few years back and the RPM's shot thru the limiter and stopped at 9400. The result was a broken crank, valvetrain...etc..we typically shifted at 7500. I dont have a horse in the race and I don't anybody involved. Just trying to keep an open mind here.

[Dwright]

I am just looking for advice as to what would cause it to hit 8k. I don't believe it is the tune. Like I said I had slippage in the trans after the torque converter was installed. Found out it was 3 quarts low. After topping off it seemed to be a lot better but I only drove the car maybe 50 miles after that. I am going to have them pull the trans pan and check the tranny. Other than that I don't know what else can cause it to rev that high. It hit 7k a few times before refilling the tranny so the damage could have already been done and the boost just finished it off. When I get in the car I drive it like I stole it. So I am not going to blame anyone. I am really just looking for suggestions as to what to check or look at before I put it to the floor again after the rebuild

[wrtowman]

From another thread...

Originally Posted by Dwright

Those are impressive numbers. I did a stage two vvt cam, Cnc heads and an lsa blower along with e85 and I was only hitting 476 rwhp but my belt was slipping and dropping to 4 lbs of boost at high rpms. But I couldn't get close to those numbers. The guy told me their dyno read low. If I hit those numbers I would be drooling.

[Dwright]

Yup that was on the numbers I was hitting on the dyno. Next day I dropped a valve. The first pull has 275 horse power. It was on the dyno for 6 hours. Not constant but while they were working on the tune

[Jayjellyfish212]

275? Stock alone is way higher ..was it 475-575?

[Dwright]

Yeah I know I had less power once the sc was installed. Until it hit the dyno. The tuner wouldn't use any of my emailed tunes and wrote a completely new map. It took hours

[camarosspower]

Originally Posted by Dwright

I am just looking for advice as to what would cause it to hit 8k. I don't believe it is the tune. Like I said I had slippage in the trans after the torque converter was installed. Found out it was 3 quarts low. After topping off it seemed to be a lot better but I only drove the car maybe 50 miles after that. I am going to have them pull the trans pan and check the tranny. Other than that I don't know what else can cause it to rev that high. It hit 7k a few times before refilling the tranny so the damage could have already been done and the boost just finished it off. When I get in the car I drive it like I stole it. So I am not going to blame anyone. I am really just looking for suggestions as to what to check or look at before I put it to the floor again after the rebuild

Maybe you also lost a gear? When mine broke I was on manual mode in 4th gear rpms at around 5500. I switched to drive mode and for some reason the transmission downshifted to 3rd which caused the rpms to spike up 8k. Motor was never the same. Just my experience.

[1KillerSS]

If you have HPT, I can look at your tune for you, I'll tell you for sure whether or not its suspect. There is more than just one place to enter a number in, if you want to set/change a rev limit. Yes there is one obvious box to enter the number in, but you also need to change a few other values in a few other places.

cutoff rpm VS gear
lamp rpm
wheel speed limit
extreme cutoff
extreme resume
startup modifiers

The control methods need to be properly selected, whether or not you use fuel, spark, ETC, or a combination of them. I am also not blaming your tuner, but if he is not familiar with ls engines or GM tuning, or even the E38PCM, which itself is a PITA, then its easy for someone to miss something.
I would do your tranny just to be safe, that's just me.

[Dwright]

The car is at the shop. I am going there today to get them to rebuild the tranny. Once I get the the tune. It would be great to have someone double check it. I do have hp tuning software

[Jeff_SS]

Originally Posted by Dwright

Yup that was on the numbers I was hitting on the dyno. Next day I dropped a valve. The first pull has 275 horse power. It was on the dyno for 6 hours. Not constant but while they were working on the tune

Lmfao you still don't think it has anything to do with the tuner...?
You really need to take it to a professional shop when you get the new setup.

I feel like we're all being trolled right now