a walker

I recently got my car out to the track for the first time since doing an engine swap and some other work. I was quite disappointed with the times my car ran.

With my old set up, I was running 12.7's @ 108. I had a full bolt on car, no back seat, Coan street torque convertor (roughly 3000 stall), 3.73 gears in a stock 10 bolt, and 245/16 Nittos. It was tuned by Dan K here on the board with a wideband on the street. I can post more specific mods if necessary.

My new set up is a recently freshened 355 stock bottom end with forged flat top pistons, COMP XFI 467 cam (230/236; .576/.570), stock heads and intake, TCI Super Street Fighter convertor (3600 rpm stall), Moser 9" with 3.70 gears. Still on the 245/16 Nittos. It was tuned by another friend with a wideband on the street. My new track times... 12.7 @105.

With the new combo, on a wet 175 shot I ran 11.4 @118. Not too shabby, but I really was hoping for a high 10 or a lower 11 second time slip.

I was hoping for a low 12 - a 12.3 would have been nice. Instead, I ran the same ET as before, but with 3 less mph. I wouldn't think the bigger convertor and 9" would eat up that much power.

I don't remember what pressure I used to run my Nittos at on the track, but this time around I ran them at 16 psi. I was getting 60' times around 1.64-1.70, but was getting some wheelhop if I tried to launch real hard. I assumed that was caused by the fact that I'm running the stock torque arm still with the 9" and my pinion angle may be off. I'm planning to get a torque arm as soon as funds allow.

Any thoughts or opinions? I can sent a copy of my tune or a datalog if somebody wants to take a look.

The_Bishop

I think that TCI converter might be hurting you. Out of all the converters I ever used, TCI was pretty consistent... at being junk.

Injuneer

All you really did to the engine was bump the static CR a bit with the flat top pistons, and change the cam. 5ci isn't going to be noticable. The cam has a lot of lift, but you're using it with stock heads. If they haven't been ported, going above 0.500" lift may not help you much, if the flow stalls - and I have seen flow charts on stock heads that indicate flow starts to drop as you approach 0.600" lift. Then you went to a less efficient rear axle assembly, and a looser converter. Then throw in potential driveline issues with the stock torque arm (the 9-inch drops the pinion 3/4", and moves it off center), and you make the driveshaft work harder, and might have picked up the wheel hop. The results don't seem all that unusual.

a walker

Thanks for the replies guys. I knew that going with a looser convertor and less efficient rear axle would "eat" some of my power, but I never expected for it to be this drastic. Obvisouly, looking at my 60' times it shows I have the "driver mod". Once I get that torque arm/wheel hop issue resolved, there will be a little more room for improvement on the little end. I just thought (assumed) that even with the less effiecient drivetrain, I would be at least a couple tenths faster than before. Oh, and I made a typo on my OP... my old best was 12.7x. My new best is 12.6x.

The one thing that really concerns me though is the low trap speed. Can some of that be accredited to the fact that I was runnign on Nittos at 16 psi? I heard "rumor" that they like to be aired up and if I tried that I may get some mph back, and possibly a tenth or two. Opinions?

Also, once I get the suspension sorted out, I will be getting some ET Streets. No idea how that's going to affect my time slips as of yet, but time will tell.

SS MPSTR

Honestly, I think your TC and rear are mostly to blame for the power loss, and not the tire entirely. There are better tires to run, and would suggest a MT ET DR to replace the Nitto. And yes, a radial does not need to be 'aired' down - run at the minimum manufacturer recommended pressure.

More seat time, figuring out the cause of the wheel hop and better tires will result in a much better ET for your combination. Your short times are actually pretty good

a walker

Yeah, my car does a lot of "daily driving" during the summer months, so I went with Nittos for the all-weather driveability that the ET Street radials lack. I have an extra pair of salad shooters I am going to use for track tires. For track duty, I am either going to go with an all out ET Street or ET Street radial, but I haven't decided which yet.

I am hoping to see low-mid 1.5 60's once I get the suspension sorted out, which I think is very realistic. That should help my suffering ET a little at least.

What is everybody's opinion on a manual lock up switch for the convertor? I have never liked the thought of it because of the stress it places on the convertor, but it may be something I would consider, just to run some better times.

Thanks guys!

Javier97Z28

That's a power hungry, garbage converter.

Converters on automatics can make or break a car. Look into a Yank or Vigilante and throw that thing in the garbage.

reamo04

if you still have the coan, put that back in there and see if that helps

a walker

I do, but it's such a pain in the *** to pull the trannies...

Maybe in the fall I will.

slomarao

Im wondering why your only seeing a 13mph gain from a 175 shot?

a walker

That may be because of my tunes. I have two tunes, one for n/a and one for nitrous use. The nitrous tune has 5 degrees of timing pulled, and is at 11.8 afr (on motor). When we tuned the car I didn't have my bottle filled, so my friend just gave me a generic nitrous "safe" tune. We're going to fine tune the spray tune with the wideband at the track soon hopefully. When I ran n/a on my nitrous tune, I went 12.9 @ 103 with a similar 60' as my other runs.

I found some old timeslips tonight while doing some house cleaning, and I realized something that gives me some hope. A couple years ago when I was running 12.7's with the stock engine, that was at RT 66 Raceway. I was never able to run that fast at Byron Dragway. The best I could do at Byron way back then was 13.1 @ 102. I thought about it some, and remembered that I typically ran about 3-4 tenths slower at Byron. Well, Byron is where I recently ran the car, so I need to get back to RT 66 and see if I can run any faster there. The only problem is that they are extremely strict on tech, so I'll get booted after my first nitrous run for no roll bar.

a walker

Just an update since I made it out to the track a couple times this weekend.

Friday I went to Rt 66 in Joliet for an evening test and tune. I wanted to see how the car drove on a different track since I wheelhopped so bad at Byron. It was a nice cool evening and the air felt good. I ran the Nittos at 20 psi this time. Didn't make any changes since the last trip to the track. I didn't see even a hint of wheehop this time. My first run I launched prett easy just to test things out. Pulled a 1.69 60' and went 12.44 @ 107.93. Went back for my second pass and launched as hard as I could, did a 1.67 60' and went 12.44 @ 108. It was pretty busy there, so when I went for my 3rd pass they told me it would be my last. I cracked open the bottle and went 11.29 @ 119 with a 1.58 60'. I didn't launch on the spray, but it looks like I hit the switch within the first 60'. Not a bad night considering I ran new bests and the car is consistent.

That brings me to yesterday. I went back to Byron. It was a nice cool day, and the air felt pretty good. My first run I launched kinda hard and wheelhopped bad. 2.1 60' and went 13.0 @ 108. Kinda pissed about the wheelhop, but was happy to see the mph up from where it was last time at Byron, which supported that the air was good. For the 2nd pass, I checked my rear QA1 shocks, and was baffled that they were on "7". I don't know why they were so firm, but I dropped them down to "3". Made the pass and went 12.47 @ 108 with a 1.70 60' and no wheel hop. Went for the 3rd run and launched hard, again no wheel hop. 1.66 60' and 12.42 @ 108. So now I'm thinking I fixed my wheel hop, and decided to go on nitrous. Launched hard on nitrous and wheel hopped really bad. Pedalled it once, then got back in it and went 11.61 @ 118.9 with a 1.80 60'. Now I'm angry. Go for 4th run, did not launch on nitrous this time, but still wheel hopped and pulled 1.81 60' and went 11.75 @ 119, again pedalling it once or twice to stop the hopping. So now I realize that all of my passes were in the left lane, so I decided to give the right lane a try on motor. Ended up with a 12.45 @ 108.5 1.73 60' with no hop. I wanted to make my last pass of the day in the right lane on the bottle, but they made me go to the left lane. Same results, bad wheel hop, had to pedal it a couple times, and only managed 12.6 @ 117 with a 2.19 60'.

Now, I know I need to get a torque arm on to correct the pinion angle, but it baffles me how I can go to a different track and not have any problems. Is Rt 66 just so much better that my suspension is less critical?

One last thought. I have QA1 "R" series front shocks set full soft. Think maybe I need to tighten them up some?

slomarao

Im not a suspension wiz but it would be worth a shot to play around some. Especially the front. Still seeing the 13 mph gain on the juice but i understand its your tune thats causing that.

Im with the other guys on the stall. Get rid of it for something else, it will help out a lot. Im not even a A4 guy and i know that.

Zeueses 97 RamAir

I have an LG Motorsports torque arm I nevr used on my car scared to break rear end 410s in the backnever put it on..

camaro1fastz28

put a slick on it and cut her losse with the juice she will go into the 10's