PewterZ28

iTrader: (1)

03/17/08
FYI...THIS TOPIC IS FOUR YEARS OLD. I'm not having these problems anymore.

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I’m running out of ideas here. I’m happy with the way my car runs but I really think my sixty-foot times are off by at least a few hundredths. My car is very light, probably just over 3,000 to 3,100 lbs without me, although I’ve never weighed it. It’s a 1SC model with about net 200 to 300 lbs removed.

My major mods are C1 Cam, YTP 4400, FLP longtubes, 3” true duals w/ x-pipe into two bullets, 4.10 gears on stock rear w/ TA cover, 26x11.5x15 QTP’s on 15x8.5 Convo Pros, complete BMR suspension including X-treme adjustable tq arm (except rear sway bar, which is still stock), Wolfe chromoly 6 point weld-in, QA1 shocks in rear, QA1 type R shocks up front with QA1 springs.

My best time and sixty foot is in my sig. DA was 67 ft. EFILive showed 4.0* KR and only 23.5* timing throughout the entire run, so I guess my total timing advance was only19.5*? However, I was dead hooking and actually pulled both front tires off the ground on that run but I still only had a 1.55 short.

While that isn’t too bad, it is when you consider the fact that I was sixty-footing 1.59 under the same conditions but way back when I was still internally stock with 3.23 gears, stock springs and shocks and using the FLP y-pipe and collector! My mods since then have given me 5 additional mph and 4 tenths but only .04 off my short.

At this point there are only three things I can think of to try/fix.
1. Find out why there is 4* KR and get rid of it.
2. Get rid of the free ram air and get a WS6 lower air box that is not cut (I have the ultra z hood).
3. Try the FLP y-pipe and collector to see if that setup was actually giving me more torque than the true duals.

I’m thinking I might knock off another hundredth or two but I still think I should be in the high 1.4’s at least. So, even if I’m hooking, is there more to be gained by playing with the tq arm or is there anything else I can do?

CHRISPY

Run a full slick

Try out the ORY with a single bullet off of it.

definitely get rid of the KR

That should do it imo

NA$TY-TA

iTrader: (21)

Big rear swaybar... Wolfe makes a nice piece......

PewterZ28

iTrader: (1)

I often hear people say you can’t beat a full slick. The only thing that confuses me about that is what if you are already hooking with what you’re currently using? In that case, it seems like it wouldn’t necessarily benefit to switch to a full slick. Is this accurate or no?

Everything I have is BMR so I’ll probably just finish my suspension with their rear sway bar unless you think Wolfe’s is that much better. The question I have is how much do you think a big rear sway bar is really worth? Would there be any drop at all in the sixty-foot time?

MUSTANGEATER

iTrader: (10)

I wouldn't undermind the power of a full slick. This just comes to mind but perhaps you're spinning the wheel on the rim?

Are you leaving completely straight when you launch the car? or does it leave a bit staggered? If you're leaving anything but completely straight the rear sway bar will help.


Off topic:

Are you running at GIR or MAR?

mongse

iTrader: (2)

What's the pinion angle on the torque arm D? Throw me a PM the next time you're going to MAR or GIR.

PewterZ28

iTrader: (1)

I probably have close to 60 passes at GIR since I got my '02 Z28 a couple years ago. Of those 60 passes, 59 of them were straight as can be IMO. Only once, just this Tuesday, did I leave a little crooked and spinning a little, which slowed my sixty down by .07. Of course my left front tire is lifting higher than my right front tire but that will always be there, it shouldn't effect anything, right?

I'm not spinning the tire on the rim because I have tubes now. They aren't nailed into the slick but the valve stem would tear the tube if they were spinning, right?

I believe Speed Inc. claims to have set my pinion angle at -1 or -2. I don't really know how to get a very accurate reading even though I have a magnetic angle finder. I've seen too many people, on this board even, disagreeing about how to measure pinion angle. I figure if the experts can't agree on it, then how the heck am I going to figure it out. Kind of like tuning, you know?

Floyd, I usually go to GIR. I’d like to go to MAR more often but it’s a farther drive and I’m using QTP’s which aren’t supposed to last very long if used on the highway. I usually go to GIR on Wednesdays but since I was hooking on Tuesday I think I’ll start going on Tuesdays more often than not.

MUSTANGEATER

iTrader: (10)

Not leaving straight would be one reason to get a bigger Rear Sway Bar, if you're leaving straight 99% of the time I wouldn't worry about one quite yet.

If Joe doesn't know how to measure the pinion angle I can ask Jay Billingsley, he'd know the proper way, which reminds me I need to call him lol

I'll prolly be hitting up Gateway quite often this summer since school gets out in about 2-3 weeks. In the mean time I'm going to be picking up a new set of Full Hoosier Slicks sometime towards the end of the week if you want to borrow them sometime you can.

Anyway To The Top for ya

PewterZ28

iTrader: (1)

Jay is either extremely busy or doesn’t read his emails. I emailed him two or three times last month about Strange front brakes, a manual brake kit and the ABS delete block. I never got a reply.

Hopefully Joe is at the drag strip next time I’m there. Maybe he could show me how to measure the pinion angle. I’ll post back to this thread if I ever figure out how to get my shorts down to the 1.4's.

MUSTANGEATER

iTrader: (10)

Yea, Jay is a busy beaver, it's better to just call and leave a message.

PewterZ28

iTrader: (1)

Well, I got an uncut WS6 lower air box and sealed it pretty well to try to make the most of the Ultra Z hood ram air. I was hoping my sixty-foots would improve a couple hundredths since some people here claimed the FRA would kill your sixty-foots. Instead my sixty-foots got worse; I lost a couple hundredths (1.59 compared to 1.57 in identical DA). I also slowed down a tenth and 1 mph, again when compared to identical DA.

My friend recorded the runs and when I reviewed the launches I noticed a couple things. One, I am carrying the front left tire about 15 feet give or take a few. Two, I am dead hooking but it appears my rear right tire is spinning about 5 or 10 feet out just for a brief moment.

Here’s what is happening in order of occurrence: Rear squats pretty evenly, front left tire lifts off ground 6 to 8 inches, front right tire lifts off ground about 2 to 4 inches, front right tire comes back down, rear right of car lifts up (space in wheel well grows larger) and rear right tire spins one or two revolutions while at the same time the left front tire comes back down, finally the rear right tire seems to catch again and the suspension seems to level out for the rest of the sixty-foot. Keep in mind the rear right tire spin is very subtle. I had to watch the videos over and over and also in slow motion to detect it. It is noticeable but barely. My point is, I still don’t think it could account for the .04 to .06 I believe I am missing.

That being said, what can I do to keep the rear right planted even as the front of the car comes back down? Adjust the front Hal springs (tighten or loosen?)? Put more pressure in the rear air bag? Please help.

Thanks for any suggestions you can give.

Derrick

V6 Bird

iTrader: (15)

THe duals will outperform the ory anyday!

V6 Bird

iTrader: (15)

Sounds like you still have your rear bump stops in place. You are probably hitting them and that is sending the rear of the car back up fast. Put your free ram air back on the car. Never run the rear shocks on different settings. Use your air bag for the preload not the shocks. Remember the more the track is hooking the tighter you run the rear shocks. The tighter the car leaves, the faster it is able to "get up on the tire" and move quicker down the track. The fronts on the R series should allow the car to lift quick but you dont want them settling back down too fast or the same thing you are experiencing will happen. Check your pinion angle with the car on rhino ramps or a drive on lift. Check it with the driver in the car if at all possible. Dpeending on what rear bushings are in the car you want to get anywhere from -1.5 degrees to -4 on the pinion angle. Be sure and measure it on the pinion and not the driveshaft. A lot of people make the mistake and measuring both and taking the difference between the two. Its really simple and some get carried away on taking measurements on it.

If the track is slippery then start to loosen the rear up. As a starting point, start out on 6 clicks from the lowest point the rears will go. See how that does and go from there. If the track isnt hooking, loosen it up one click at a time. Isolate your variables first. Get a consistent tire on it. I prefer M/T Et Drags and with that much gear id even look into a 28" for your application and converter.

PewterZ28

iTrader: (1)

Ok, I’m going to the drag strip tonight and I’m going to heed your advice. I currently have the Front Left QA1 on 2, FR on 1, RL on 4 and RR on 5. I’ll put both front ones on 2 and both rear ones on 6 and put the RR air bag up to 20 psi. I also brought my stock lower air box that is cut. I’ll make a couple passes with the WS6 lower box and a couple with the FRA box and see if there is any difference at all.

I was told the bump stops had to be left in with the QA1 shocks. Is that not the case? If not, should I use some rubber tubing over the first coil?

Finally, if anyone has a picture they can post with arrows pointing to the proper place to measure the pinion angle from, please post here. In the mean time, can’t I just blindly adjust the pinion to a more negative position, without over doing it of course? I’d like to play with it at the drag strip tonight.

PewterZ28

iTrader: (1)

Well, I had some luck last night.

Here are the details from last night’s runs:

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1st Pass (DA = 1581’)
Set front QA1’s to 2 and rear to 6. Set rear tire cold psi to 18 and rear right airbag to 21 psi. Used WS6 lower box, sealed pretty well. Added one gallon of 110 unleaded to try to determine if the KR I continually get is false or real.
1.601
7.439 @ 91.50
11.669 @ 115.66
EFI Live showed 23.5* timing with 3.9*KR tapering slowly throughout the run to about 0.9*KR at the traps. Apparently the KR is false since I had just added 110 unleaded. O2’s averaged about .950’s.
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2nd Pass (DA = 1421’)
Got some help from an old friend. We bumped up my timing considerably. Apparently the ’01 and ’02 LS1 F-Bodies have very low timing advance compared to the earlier model LS1’s. We increased the timing down low starting around 1800 rpm and continued to increase as far as the table would allow us. I also programmed the converter to lock up a little later.
1.571
7.423 @ 91.43
11.695 @ 115.40
EFI Live showed timing going from 19.5* at stall speed up to 27.5* above 6000 rpm. Here’s the weird thing though, no KR this time! Did the timing increase have anything to do with it or did it just perhaps take a while for the 110 octane to work its way through the fuel system? I would like to get some opinions on this. Also, the 02’s were averaging in the .920’s now.---------------------------------

3rd Pass (DA = 1175’)
I have not been very impressed with the WS6 lower air box so I put back in the stock lower box with FRA. I also set the rear QA1’s to 7.
1.564
7.344 @ 92.44
11.572 @ 115.74
Unable to log run as my laptop battery was dead. Sixty-foot improvement over 2nd pass could have been attributed to the DA improvement. MPH in the 1/8 was up 1 but did not increase in the ¼. I’m not sure why, the headwind was the same as the second pass, 7 mph.
--------------------------------

4th Pass (DA = 1035’)
Still using the stock lower box with FRA. Set rear QA1’s to 8.
1.557 (tied my best ever, which occurred on my 11.3 run in 70’ DA)
7.329 @ 92.88
11.537 @ 117.38
I finally found my missing mph in the ¼ but I don’t really know why. Headwind was the same as other passes and 1/8 mph was the same as previous pass. Launch felt like most of the energy was used moving forward and not spent lifting the front end. Perhaps the rear shock setting and increase in air bag psi helped. I’m sure the timing increase helped a little bit also. If I had zero DA the sixty-foot might have been in the 1.52 range, which is very close to where I want to be.
---------------------------------

It’s hard to say how much the DA improvement throughout the night effected the sixty foot times but I would say the shock and air bag settings played a role as did the timing increase. Also, I have always read on here that the FRA mod kills sixty-foot times. That was not the case at all last night, in fact, every pass I’ve made with the WS6 lower air box has been about one to two tenths slower and 2 mph slower. I will test both air boxes one more time just to be sure.

Overall I think I am only missing about three-hundredths in my sixty-foot times now. Perhaps more timing, better air/fuel tuning, as well as playing with the torque arm will help me find those last few hundredths. I’ll keep you posted. Please feel free to comment on the KR issue, the O2 readings or anything else you may have an idea about.

PewterZ28

iTrader: (1)

ttt...

PewterZ28

iTrader: (1)

ttt...

V6 Bird

iTrader: (15)

I dont liek that you have the fronts on 2 though. I run mine no less than 4 in most cases and the cars till wheelies hard on launch so i usually run them on 6 to 8. Sounds like its leaving good now, but why do you still have the airbag in the spring? Throw that to a mustang and yes take the bump stops OFF. No you dont need any rubber on the first coil either. You will almost never hit where the bump stop used to be unless you hit a bump goign to fast and completely bottom out the car.

Good results nonetheless. Keep it up. I would say that the pinion isnt very far off with 60's where they are at now.

KR could be coming from a excess of fuel in the chamber igniting after leaving the cylinder, something banging somewhere, etc.

DA helped you alot as well. Most of your improvements are from the DA getting so much better than when you started. Thats a guarantee!


Mike

Pro Stock John

iTrader: (34)

Well, I would:

-run rears at 4 left, 5 right
-run fronts at 2 left, and 2 right
-stall up the yank tp4400 as high as possible, over 2500 might be possible, magnus was almost 3k and cutting 1.47-1.48's
-if your FLP's are hitting the floorboards, maybe put in poly motor mounts, I have huge 3.5 collectors and they never hit now
-anti roll bar will keep the car level out of the hole, but what do you stall the yank to now?

PewterZ28

iTrader: (1)

I was taking your advice. You said, "Never run the rear shocks on different settings. Use your air bag for the preload not the shocks." You didn't say to remove the air bag. I'm curious though, how can the airbag hurt any? I don't have a rear sway bar yet so I would think it would be best to leave it in until I do. Is that not correct?

John, I stall the Yank up to 2700 to 2800. Any more and the car creeps forward. I'm still brake torquing, a line lock wouldn't help my sixty-foot times would it?