wanted to dig this up and see what you found out about the car's performance..

I haven't been back to the track since then but I do have the true dual exhaust installed. It definitely pulls alot stronger since the last time. One of these days I'll go back and test it.

post results here when you go back, our combinations should be similar. Back when I first got my 383 (before I rebuilt it and did my own tuning) it had 70% leakdown on #7 cylinder, and was 15:1 afr at WOT. With low compression and a terrible tune it put down 340hp and 400ftlbs to the wheels and ran a string of mid 12s, best being 12.48@114mph on street tires with a 2.0 60ft.

Now, like you, I've freshened the engine and gotten it tuned properly, every time I go to the track something goes wrong. Last time I was out we were in Bristol TN on the power tour. The weather was horrible and I was leaning out on the top end due to the higher elevation and was only turning high 12s. All of the hardcore drag racers there were saying they were 1 to 1.5 seconds slower than their best for the day so I felt pretty good that I could scrape a high 11 on street tires, but I've never been able to do it yet.

I'll be sure to post up some numbers. I have to say that I did race a Kawasaki Ninja the other night and won on a 75shot . I'm not sure which Ninja it was but the slowest one is the ZX6 which is a low 11sec bike.

Nice work! LOL

have you been to the track lately? got any posting of times.

I haven't been to the track lately. Every time I get a chance to go they either close it due to rain or there are a million 14-15 second imports already there.

How big of OD are your tires? Are you shifting in to 4th or are you leaving it in D at the track. What's your redline RPM and where is your trans shifting at?

I am late to this party but here is my imput. You dyno'd some great numbers. You got to the track and it didn't run even close to that power level. When you found that hose sucking closed that had to be the problem. You wouldn't need to change anything if you were satisfied with the Horsepower you made at the dyno. You only needed to figure out why it lost power at ther track. I am sure you have found the problem. I read the whole thread and it did seem like some kind of restriction. You were probably losing most of the potential air you could get. If that isn't a problem any more then you will ran much better this time you go to the track.
Good Luck
Dave

Tires are 26.6" OD. I have a WCT5 which is part of the reason for the slow times. With the torque the engine is making I was sure to grenade the T5 in a few hard launches. I wanted to drive it home. RPM cutoff is set at 6500.

Interested to see if you got it figured out...

You mentioned earlier that you were sucking the air intake closed. That would absolutely kill your horsepower. Like I was saying I think you have solved the mystery. Now whether you bust a high 11 or just run a low 12, who knows. I'm sure your traps will jump a good 10mph.
I am interested in hearing what it can do.

I will keep us posted on the results. It's been raining here everyday for almost 2 weeks.

That's got to be it. Intakes don't just crush down flat for no reason- vacuum was building inside of it becuase of a restriction and sucked it flat. You're going to run much faster next time out.

Are you running your car as set up from your dyno session? Something is not adding up. Based on Lingenfelter's book and your HP graph, you should be shifting from 1st to 2nd at 6200 and around 6000 from 2nd to 3rd.

You can get a 4" exhaust from Mufflex. But if you are running your car as set up from the Dyno, something is not adding up. With your injectors running at .45 BSFC (lean) you should have 450HP at the flywheel which adds up to about 380HP at the wheels assuming a 15% drive train loss for the T5. You're supposed to get a 12.6 time slip with a 3600 lb car assuming perfect traction or a 13.19 time slip on street tires.

where is your wide band installed? did you do a/f ratio on the dyno in the pipes?

i made 380/420 ft lbs with my 305 and ran a best of 12.6 at 110mph with a 1.69 60'

i have a 3.73 12 bolt and a tremec tko shift light came on a few seconds before the finish in 4th

my lc1 is installed just after the headers and it was actually leaner then what the dyno had in the pipes

wideband is installed in the y-pipe. a/f during the run was around 12.5 but then richened up at the top.
main reason for the slow times is because of street tire spin. 60ft times are terrible at 2.5sec average because i didnt want to break the tranny

i hear that, i sold the good working t5 before it blew up in my face.

How heavy is your car? I went 12.48@114mph with a 2.2 60ft. I dyno'd 340/401 at the wheels on 7 cylinders and a 15:1 afr...

never weighed it so i'm not sure