What to do now?

[Drothgeb]

I built my truck with the S/DD class in mind. It's been tough to this point though.

About a month and a half ago, things were coming together, and I blew the output shaft. Next time out, 11.97@113 first pass. Then the intercooler split on the second pass. Next time out, I blew the head gasket driving to the track. While taking it apart, I discovered that the thrust bearing had gone bad in the secondary, and the compressor wheel had kissed the cover. This is getting expensive.

I felt like I needed to pick up a couple of tenths. So while I had it apart, I upgraded the primary from 75mm to 80mm, but kept the standard 5" cover. And I had a mild P&P job done to the head along with O-rings and a valve job. It seemed like that should be good for .2-.3 sec. Didn't do any fueling mods at all.

Well, finally made it to the track last night. First pass, it seemed to be running really well, but a couple of hundred feet from the line, water on the windsheild. Damn!!! The first thing that crossed my mind was head gasket, so I backed off and coasted the last 100'. I was pretty annoyed, until I picked up my time slip.... 11.21@120mph
:woohoo::woohoo::woohoo::woohoo::woohoo::woohoo:
Did I mention that this was on my 7 year old LTXs. And, the best part is, the leak was only the water pump.

An all out run should be at least an 11.1, maybe even a little better with a little more timing. Drag radials should give me 10s for sure. But with better traction, I'm thinking about the output shaft going again, and probably something else too.

So I guess my question is..... I'm already going a lot faster, and making more power than I had planned. Should I be happy with that, and step it down for the S/DD class? Or should I keep beating it up and go for 10s? My inclination is to go for 10s, but tires, wheels, roll bar and etc are getting $$$$$.

 

[khaoskustoms]

Go as fast as your budget allows. The faster you go the more parts you will/can break. Its better to have a fast and consistent truck then a one hit wonder.

 

[Big Blue24]

Alot of the trucks that are competitive in the Super Diesel 11.90 index are capable of 11.50 or quicker. You just need to tailor your launch (slower more consistent 60') to where you run close to the index.

Some guys even have a small adjuster knob to step-up their tuning or a nitrous kit to give them that last little punch if they leave too soft or spin so they can still run the number.


My thoughts: If you have a mechanically injected truck that is difficult to precisely tune, build it with enough power to easily run quicker than the index and fender-race each opponent. You do need to have a good feel of how quick your truck can run all-out so you don't make a low 11 pass and then try to shut it down 20' before the finish line and still break-out.



If you have an infinitely tune-able electronically controlled truck, dial it in to run the number but add an adjustable power knob or small nitrous kit just in-case you spin or have some other mishap that causes you to run slower.

 

[4neatr]

Remember that the line is very small now between the SS and PS trucks, the SS trucks a couple years ago were mid to low 10's, now they are in high to mid 9's......it is a huge jump between the SD 11.90 bracket and mid 9's

 

[NickTF]

Are you still seeing the fairly high boost of 90ish psi?

 

[Drothgeb]

Are you still seeing the fairly high boost of 90ish psi?

I don't think so, but I'm not positive.

After putting it back together, I took it really easy for a couple of weeks, waiting for the O-rings to seat in. Even did about a half dozen re-torques. The day I took it to the track, I pushed it some on the way, and it seemed to be in the 70s, but I could only push it so hard before it would start spinning.

On that first pass at the track, I was surprised how much more power I was making, so I was more concerned with shifting and etc, than looking at the gauges. From a quick glance it apperared to be just under 80psi, so that's about 15 less than I had been making. I'm thinking that the porting really helped out there, and I'm real happy about that except........

At the track after water leak, I spotted the rust trail coming out of the water pump vent hole. So I was thinking bad waterpump, not a big deal. Over the weekend I replaced it. But as my luck goes, it wasn't the only leak. It turns out that I also blew the head gasket, and water was running out and around the water pump. DAMN!!!!!!

So, for the fourth consecutive time, a day(minutes) at the track = days of turning wrenches, and $$$$. And this time I didn't even get in one full pass.

Not sure what I'm going to do from here. I won't have time to tear it down for a couple of weeks, so I'll wait and see what happened, before I decide what to do. But really, all of that head work, O-rings, heavy duty studs @ 140lbs, you would think that it would hold up longer than 11 secs. I was really careful about taking it easy, re-torques, and etc too. I even re-checked the studs yesterday, no movement @140lbs. I even marked them, backed off and tightened again, still all good.

I'm thinking if I pull the head and all looks good, about the only thing that I can do, is go with a thicker gasket to drop the CR a little. But I'm not sure.

To be continued..........