F8L Z71

Ok so I installed the 90mm TB but have not tuned for it yet.

I removed my tailgate and my subwoofers for a total of 135lbs.

I put on my 31" tall 265/75/16 tires vs my 285/75/16s (10lbs lighter each)

Total was a lot hotter than the last time out when I ran a best of 13.92@100.8mph 2.08 60'.

Before the sun went down I was running consitant 14.0@101.8 mph 2.3 60's

After the sun went down I tried lauching in 2wd and didnt get any wheelspin and still pulled a 2.26 60' WTF? No wheelspin with the Radix?

After an hour long cooldown with temps dropping big time (from high 80s to 60s) I ran in 2wd and I spun like crazy (2.62 60') but trapped 103.2 mph! Wow! Didnt expect that.

<Question #1> Ok so stopping right here I have a question: Can tuning be the culprit for my bad 60' times? I mean is it pulling timing down low so that the truck ends up a total dog when it does, then sometimes it doesnt pull the timing and the truck takes off fairly well? It just seems like the truck is fairly consitant then all of a sudden it will drop 2 10ths in 60' for seemingly no reason.

Ok so after that run there was a nother very long cool down period and while the blower was still warm the rest of the vehicle was pretty cool. I ran in 4wd and launched off idle. I never raised the launch RPM more than 100 rpm above my 800rpm idle. The truck launched pretty hard (compared to normal) and ran really hard through the rest of the 1/4mile. I ended up with a 13.512@104.3mph 2.03 60'!

<Question #2> Are these Radix systems very tempermental to heat soak and cool down periods? I mean had the truck not felt so damn good on that last run I would have thought the timing light was messed up. That and the guy I had been racing was WAY behind me compared to the last few races.

So anyway, 13.512@ 104.3mph 2.03 60' is my new time for this setup @ 5psi avg.

I'll post back up after I tune for the 90mm TB and install the new TQ converter.

zippy

With your 3k stall I'd have expected a much better 60' than you achieved. Even with a stock converter you should have been seeing 60's in the 1.9's in 4wd. I'd say your tuner has the timing curve a bit too weak down in the lower rpm and probably has it a bit too rich also. One big trick to getting a strong launch with a Radix truck is to do alot of work when tuning with the IAT table. Many tuners don't work at that table and with a Radix being the heat maker that they are you can gain quite a bit by using this. My other suggestion is to just keep launching off idle with the Radix. I've worked with many of them and coming off idle consistantly has given my the best times as long as you have the tuning set up for it.

thunder550

iTrader: (70)

I found by logging that I was getting a weird combination of burst KR and normal KR when stalling as high as I could in 4wd. It wouldn't do it in 2wd, and if I just mashed it from idle in 4wd it wouldn't do it either. I was down to something like 6* timing between burst knock (which pulled like 2-3 degrees) and KR, which pulled another 4 degrees. The low RPM high boost timing table is pretty low to begin with, I think somewhere in the range of 12* or so.

Even now for me, with mods in sig, I can only get a little squeal out of the tires when I mash it from a standstill in 2wd, won't really spin the tires much. I'm not sure what the deal is, it may just be that the low RPM high boost timing is too low to get much out of it, or maybe the new cam is killing me. I dunno for sure, but when I brake stall and get the tires spinning a little that way, then pop my foot off the brake, they light up good. I am not impressed so far with the new setup, but I am hoping that it's just a tuning problem.

I have found that my times are very dependent on heat. When I was running hot laps with the stock clutch fan and no meth or water spray, I was losing a few 10th every run. Started at like 14.4, then 14.8, then 15.1, then 15.5. When I let it sit for 2 hours or so then ran again, I was back into the low 14's.

Now with the e-fans and meth/water injection, I can get my IAT's down into the 90's in the staging lane (probably 20* above ambient), then spraying down the track they only raise a little bit. This has helped tremendously. In the staging lanes I leave the engine running and I have a manual switch to turn the e-fans on high, so I'm constantly pulling air through the intercooler.

My best #'s with the 5.3 were 13.57 @ 99, 1.92 60', 365 rwhp, 410 rwtq. That was with a 210/218-551/551-116 cam and a 3" pulley at about 10 psi.

thunder550

iTrader: (70)

What kind of timing are you running at low RPM high g/cyl #'s? Do you have any LQ9/Radix tunes that you'd be willing to share with me?

zippy

Sure do. E-mail address?

thunder550

iTrader: (70)

sent you a PM.

F8L Z71

Zippy, that is a big part of my problem is that its not a 3k stall. It suppoed to be but it only flashes to about 2200-2400rpm and my cam would MUCH rather see a 3000-3200 stall for sure. I have a new one sitting at Ricks shop. I just need him to fit me in to swap it. This 80E is a pain in the *** sometimes but being able to cross the beams in 2nd gear at 104mph was pretty cool lol

Even this being the case I agree that it is most likely a tuning issue. We tune a lot on the dyno but I have done zero street tuning and as such there as some things I can feel on the street that wont show up on a dyno. I cant blame Rick because I told him not to spend too much time on the tune since I would be right back to retune anyway. Just make it safe

Im starting to feel better about this being a timing issue with both of you syaing the same thing. If I stried to push up against the brake realy hard by stalling it up it would get worse and worse. The the point it would actually lag like I had a turbo on it and not really take off till Im fully passed the staging beams. Im going to talk with Rick on this and see what we come up with.

trever1t

iTrader: (14)

Congrads on the new time Justin!

F8L Z71

Thx bro


Zippy, could the better off-ilde launches stem from increasing heat while trying to stall it up? I was thinking that by pushing against the converter you would be increasing your IATs which would drop timing or you'd get the KR bursts Thunder mentioned AND you are heating up the trans. I noticed after a run my lil B&M trans cooler was HOT!

Whippled 496

iTrader: (4)

These items hit pretty close to home for me as well. I show quite a bit of burst knock intermittingly, meaning sometimes it will show up and pull up to 4-5* of timing and sometimes it wont show at all. The tuner and i are stumped because it will only do it about 50% of the time. When i go WOT from a 20+mph roll it will pull timing maybe 1 out of 10 times. When i launch (4 hi) from a dead stop, it will do it 9 out of 10 times. We have pulled back to 12* at full boost and still see it. We zero'ed out the burst knock table and still see it, we decreased the KR sensitivity and still see it. The only thing we could come up with was that my AIT's were a little high, but i have no way to measure that. I was leaning out a little too on top of that, my 43lb'ers are at 106% duty cycle now.

I also noticed Friday night that if given a 1/2 or more to cool down, my 60' times and my 1/4 ET were noticably better. For example, my first run was a 14.6 @ 91mph with a 1.97 60'. That was after driving 15 miles and some idling in the lanes waiting for my run. My next run allowed for a 30 minute cool down and i ran a 14.3 with a 1.93 60'. After that run, they opened a few more lanes and i rolled right back up to the line and with no cool down at all...i made a terrible 14.8 with a 1.99 60'. My fourth one was a similar run with almost no cool down. The last run, i had to wait about 45 minutes in the staging lanes. The last run i made a 14.10 @ 94mph with a 1.90 60'. My best run of the night. So it would seem that with the non-intercooled whipple, a considerable cool down between runs is needed as well.

I found that i get much better 60' times by pushing the converter. I two foot it up to about 1500rpm's and then let loose. This is with a stock converter and it always proves to be a better 60' and ET that way.