I thought I had finally figured out what mods I would make to my 1994 Corvette Coupe but I'm finding too much information that is only confusing me more and more. I have a stock LT1, automatic that has a Dana 44 rear end with 3.43 gear, the torque converter has been changed to a Pro Torque unit with a 2800 stall speed. The car has a Power Effects exhaust system from the cats back. I bracket race the car on BFG Drag Radials and have a set of ProStar Weld wheels with Monroso front drag tires for use in 2006. The Corvette was running low 13.3's and high 13.2's at the end of the year before back surgery caused me to miss all of 2005. My wish was to get the car into the high 12.9's with a cam change and changing over to 1.6 roller rockers (and the correct springs) plus adding a set of shortie headers.
Then I read the Vette article on the Hot LT4 Coverssion by Nathan Sheets, I talk to Nathan and learned the results of his changes have gotten his LT1 into the low 12.9's. Now this month's Vette has an article about different mods to an LT1 based on dyno testing and the use of an Accell Ram Air intake manifold - I'M REALLY CONFUSED ON WHAT TO DO! Can someone out there make some sense out of all this information? I just want to make the high 12.9's. I've located LT4 heads and intake if that's the way to go or I'll buy the Hot Conversion set-up from GM if that is the way. It just seems that each time I make up my mind what to do new information comes out that makes me question my plans and how I'm spending my money. Help!

 

LT4 hotcam will get you into the 12s and it should be further than 12.9. I would not spend money on the LT4 conversion; I would just have the stock heads/intake ported and add new rockers.

 

I always take the magazine articles with a big grain of salt. The flashier the headline the more people read and hence the more magazines they sell. That and they have a tendency to leave out details about how they got the great improvements. Plus it's not their money so spending 2 grand to pick up 5 HP is OK with them. I just use the articles as a starting point and check with people in the real world (is there such a thing?) and look for info here on the Forum. My two cents only of course.

 

with the almighty Vadar!!! I have an LT4 and I absolutely love it!!! But it is not worth the $$$ to convert an LT1 to an equivalent. Your money is best spent on either a damn good set of heads or reworking your stock LT1 heads.

Another forum member (STL94LT1) had his heads reworked and they far out flow what my LT4 heads will flow stock!!! I'm sure that the LT4 heads can still out do those numbers with the same work, but then you are talking about the cost of new heads and then the cost of reworking them... by then you could have gotten some bitchin AFR's or Brodix heads... just food for thought.

I have a hot cam in my LT4 so basically your concept will yield you my results (in a sense). Mind you I was running on BFG KDWS's and not a sticky track tire, but I was able to put her at 13.223@108.4. The mile per hour is indicative of a 12.5-12.6 run if I could get her to hook. Also consider that this is just the cam I have not done headers or a tune yet... so there is still some hidden horses under there somewhere

 

Bill, Nathan has done a lot of research and testing and come up with some very good info. Im not knocking Nathan but your results should be better due to the automatic. There are a few on here such as John mackey who ran mid 12's with 3.73 gears, a stall converter, and a few bolt ons. I ran a best of 12.91 on a stock motor, with a generic chip, 3.54 gears, a 3000 stall converter and stock michlin tires. With a hotcam, headers, stock exhaust, ported heads, 3000 stall converter, and 4.09 gears on ET Streets I have run a best ET of 11.96 and a best mph of 115.81 mph.
IMO your best bet is to do heads, cam, and headers all in one step. Doing it individuadly like Nathan did really lets you see the results but man is it a lot of work.
Oh, one other thing, consider LT headers instead of the shorties.

 

Plenty of Porting options out there that will beat the LT4 heads for half the money.

 

I hate to say it but you should have already been in the 12s. What are your short times? You're losing some serious time somewhere.

 

Thanks for the multiple feedbacks
Below are the times for three different runs that have been typical for my Corvette.

Dial: 13.35 13.30 13.28
R/T: .544 .508 .521
60': 1.688 1.657 1.681
330': 5.145 5.143 5.090
1/8: 8.099 8.089 7.995
MPH: 79.44 79.79 80.15
1000': 11.078 11.061 11.001
1/4: 13.342 13.292 13.286
MPH: 101.10 101.98 102.22

Hopefully this give someone a clue to were the power is hiding

 

Bill, your car is falling on its face on the top end. comparing your trap speeds with your ET's and they are very unbalanced. To give and example my 60' times are 2.02, 1/8 mile is 8.94 @ 80mph and 1/4 mile is 13.87 @ 99mph. with my calculations with your 1/8 mile times alone you should be running at least 12.5 1/4's. Your 60's are also in line to run mid 12 runs. You need to find out whats sapping your HP, check your fuel filter, plugs, etc. etc. but something is wrong.

Greg

 

Headers and a tune....WILL DO IT!!!

 

Your 60' and such are great. Curious, what RPM are you going through the traps at? How's it feel in third gear? I'm almost wondering if you have a restriction in your stock cats or something. Either that or you're just over geared until you improve your breathing and upper RPM power. I would do the heads, cam and long tubes definitely if you can get away with them in MD.

 

Bill, I have the same setup as you on my '93. At E-Town in the good weather, I have hit 12.50@108 with 1.67 60'.

In the dead of summer I'm running 12.9-13.10@104.

 

I would try the 1.6 RR's with springs first, then do headers.
Good Luck.

 

My car is almost set up the same as yours.. I'm using a 2800 Pro Torque converter.. I still have the stock exhaust manifolds & cats on it..

Last week in Dover it ran 12.6 at 112 mph I think you might have low fuel pressure or a clogged cat..

Here are my times from 3 weeks ago

60'........ 1.81

330'........5.30

1/8th... 8.24 @ 85 mph

1000'... 10.75

1/4 was off because I was on the breaks.it ran 12.90 @ 105 mph