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Discussion Starter #1
Hello all. This is my first time out as a new member and thought I'd share some info and maybe get some insight on my projects. I've been drag racing a 93 Z28 LT1 for the past couple of years and have concluded that it is difficult at best to be consistent with a stock fuel injected engine. The ECM compensates for everything while doing it's job of maximizing engine performance. The car will get faster every hour after dark when the air begins to cool which makes choosing a dial-in a crap shoot. It's fun to drive but doesn't help with winning anything. I race foot brake at the local 1/4 mile track and eliminations begin at 9:00 PM so my time trials are steadily getting faster as the evening wears on. The few bolt-on mods are shorty headers w/ypipe and a small muffler, hypertech chip, TH350 w/3500 stall, 3.73 gears and M/T drag radials and skinnies on draglites. Dead of winter it runs 12.80's and mid summer it'll run 13.50s My new thing is the nova. It's currently in the "working out the bugs" mode.
 

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Hi and welcome to the forum! A very nice read on your car!!
 

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Discussion Starter #3
Carbureted LT1 nova

The nova is set up with a carbureted 383 LT1. It has a modified Victor Jr instead of the GM dual plane. I wanted the advantage of a single plane and this is the only option as far as I know. With the heads and cam setup it runs really strong. We took it to the track and made five passes only to figure out the torque converter was too loose. It stalled at 4900 and I didn't want to go over ~6000 so needless to say it was on the rev limiter for most of the pass. It still ran a best time of 11.98 at 108 MPH so I think we may have something here. The converter went back to BTE for adjustment and should be back today. I had them set it at 3500. I really like the power this engine is making. With 11.0:1 c/r we can run pump gas at a decent timing setting which makes for economical racing. I don'k know that this is possible with a conventional small block.
 

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The nova sounds like a good runner, should work real well with the new converter. Is it possible to add some weight to the car as the night progresses to slow it down so you have more consistency in your ets?
 

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Discussion Starter #5
The nova sounds like a good runner, should work real well with the new converter. Is it possible to add some weight to the car as the night progresses to slow it down so you have more consistency in your ets?
You know, I tried that. I put my tool box in it one evening to see what it would do and it still ran slightly quicker. I tried shifting sooner too but it got confusing real quick. I figured the key is to keep everything the same and adjust the dial-in so I started taking notes using the thermometer on the mirror of my truck and actually got to where I could guess a little closer. I have a chart I made for dial-ins at certain temps. Of course, the barometric pressure differences screws it up too but I got a lot closer with the chart.
 

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Discussion Starter #7
I haven't had the nova weighed yet but it's basically empty inside with a six point cage and a racing seat. I'm estimating 3000# +-. The bumper shocks and filler panels, dash and other non necessary weight has been removed. It still has all the glass though. I set it up to run electronics and the track changed up the rules so I pulled the box and I'm going to run foot brake with it this year. I'm anxious to get it back to the track and see what it'll do. The converter is back so I'm headed to the shop to install it. I really think the carb on the LT1 is the ticket. This has been a real low budget build and what a surprise.
 

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Discussion Starter #9
The transmission is back in and it feels better but you just don't know until you get it on the track. We race again tomorrow night and I just found out I may have to work late tomorrow. That Sucks! If I can get off at a reasonable time I may just take the camaro and try the nova next week. I hate to take it out without running it around a little. It is nice having a backup race car though and the camaro is old reliable.
 

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Discussion Starter #11
Yeah, we do get to race all year except for the occasional rain out. Although they did cancel racing one week because it was forcasted to be freezing that night. I don't think it got that cold though. I wouldn't mind taking the camaro out when it is really cold like in the 20's just to see if I can get it below 12.80s.

My plans for testing the nova tonight got busted. I got off work too late so I have to wait till next week. It never fails that your job or something gets in the way when you think you finally have everything fixed and lined out and you just know it's going to beat your best ever time and... well, it just Sucks. Big time!
 

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I've been drag racing a 93 Z28 LT1 for the past couple of years and have concluded that it is difficult at best to be consistent with a stock fuel injected engine. The ECM compensates for everything while doing it's job of maximizing engine performance. The car will get faster every hour after dark when the air begins to cool which makes choosing a dial-in a crap shoot. It's fun to drive but doesn't help with winning anything. I race foot brake at the local 1/4 mile track and eliminations begin at 9:00 PM so my time trials are steadily getting faster as the evening wears on. The few bolt-on mods are shorty headers w/ypipe and a small muffler, hypertech chip, TH350 w/3500 stall, 3.73 gears and M/T drag radials and skinnies on draglites. Dead of winter it runs 12.80's and mid summer it'll run 13.50s My new thing is the nova. It's currently in the "working out the bugs" mode.
This is where data recording comes into play. You need to know the weather conditions for each pass, including air temp, humidity, barometric pressure, and wind speed & direction. As the database grows, you will be better able to estimate what to dial in based on what the weather conditions are as you roll up to the line.

It doesn't matter whether the car is computer controlled or a dumb carb set-up. What you describe is exactly what I have been doing since 1997, especially the Friday classes where time trials start at 4 p.m. and eliminations start at 7 and racing can go on until midnight. Last June on a Saturday, we started time trials at 10 a.m., eliminations started at 1:30 p.m., halfway through the first round of the 3rd class it started to rain and we sat it out. 2nd round started after dark, completely different conditions than we had in time trials, and I went to the quarter finals in a computerized stick shift car, including running my dial-in to within 8 thou, even though I hadn't been racing that car that long - I just went on the data I had.

On the other hand, I've had the carb car change a tenth on me from run to run with no apparent changes in the weather, car temp, tire pressure, etc. I've also run my dial-in to the "zero" several times (usually when the other guy broke out). Often I simply didn't know which car I was staging.

When I debuted the LS1/4L60E car last fall, it was all over the place for me. Before the last race of the season, I finally got around to installing the axillary transmission cooler, and it settled down and went rounds the last race. It was following the weather station beautifully.

So don't try to tell me that carbs are more consistent than computerized cars. That dog don't hunt.
 

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Discussion Starter #13
So don't try to tell me that carbs are more consistent than computerized cars. That dog don't hunt.
Well now, I don't try to tell anyone anything. I simply acknowledge my conclusions. However, at this time I am going to do some research and see if a carbureted LT1 engine that I built can perform under similar track conditions with the same driver (me) more consistently than the "basically" stock fuel injected LT1 that I've been running. Added to the equation is the fact that the nova was built for one purpose, to race. A two speed transmission can be more consistent than a three or four speed, not always, but it can (for example). So at the end of the day, if I find that the dog does indeed hunt, I'l be content to kindly disagree with you and leave it at that.
 

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Discussion Starter #14
to Five7kid's point, if you can monitor all conditions that affect the performance of these engines, one can get there dial-in real close. I guess you have to get to know your car and taking notes is the way to go. I've raced this car for two full seasons with absolutely no changes (other than fluids and filters) and both years saw a .7 second swing in ET from hot months to cold ones. I don't think alcohol racers see that much swing but I'm going to see what the carbed LT1 will do. I'll know by this time next year. All in all I think the LTx platform is an excellent engine for racing or street simply because it's affordable, powerful and well supported by the aftermarket folks. It also offers a lot of flexibility because of the similarities with the first generation small blocks. I think the opportunities are endless and for those wondering why anyone would put a carburetor on an LT1, it's cheap power for racing. Just think of the cam profiles one could apply... and never need a tune.
 

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Discussion Starter #15
The track is having a race this afternoon so I'm headed out with the nova to see what it'll do. I'll post the results when I get in tonight if I have time.
 

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Discussion Starter #17
Yep, had some good, clean passes. Seven to be exact. Best time, 11.37 @ 118 MPH and 1.65 60 Foot. The car hooked well, the torque converter loosened up and worked good. I had fuel issues and could only get a good pass by shifting at 5000 RPM. Larger carb and fuel pump and line will fix it though. I think the coolest it got tonight was around 74 degrees which isn't bad. You gotta love the LT1.
 

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Discussion Starter #20
The nova's engine details out like this if I can remember it all: Forged crank, original LT1 rods, Mahle forged single eyebrow pistons, Comp Cam 236/248 @ .050, .525 lift and 110 LSA, and a pair of home ported 96 model heads. I don't remember the casting number but they're the ones with the slightly larger valves and less meat for porting. Electric water pump and factory alternator on the outside. Everything else including the valve train is stock LT1. (stamped steel rockers included) I actually have more money in the powerglide than the engine (but not by much) and it works great. It now stalls around 3200 which I'm hoping it'll loosen up a bit more.
 
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