Would they compliment eachother, or would a gasket matched ported plenum and base do just fine? I want to keep my HP-per-$$ ratio as low as possible.

I haven't heard much news on LT1 intakes on LB9's. So I'm assuming that the gains aren't worth the money and time involved. So would 3.73's be ok with a ported plenum?

I also plan on other top end mods in the future like headers and rockers.

 

just a LT1 intake on a stock Lb9 bottom end would be not so good LOL

LT1 intake is for up to 6000rpms or so and stock Lb9 auto cam wouldnt support that at all. you will loose alot of torque and power more than likely.

if you want an Lt1 intake, get a cam to match for the 305, else it would be a waste. TPI isnt bad for a 305 cuz thats what it was designed for. 3.73's should be fine with a fully ported TPI but that cam in the LB9 auto cars is just too small.

you can run them for now but deffinately look into a bigger cam to go with fully ported TPI (base and plenum port) or the Lt1. that way your power band will be up to 5500rpms or so and will go great with the 3.73's.

 

You haven't heard much on LB9 and LT1 intakes because only a few people have done it. Actually they didn't use a LT1 intake, they used a L99 intake off a 4.3L V-8 Caprice. It looks exactlty like a LT1 intake except it has smaller ports for the smaller cubic inches.

Last time I checked the 305 LB9 5.0L was a bigger engine then the 4.3L L99 engine so your fine there.

I wouldn't go much more cam then a stock or slightly larger 350 cam in your 305. Cam choice is more dependant on cylinder heads then intake. If you run good heads you can run a good cam.

3.73's are OVERKILL in a TPI 305 car. You will loose track times with gears that low. I would get 3.42's max unless the 305 is built to spin high rpm's. Just a LT1 (L99) intake doesn't qualify you for 3.73 gears.

 

For SD car all Lb9's got the L98 cam. I have a '91 Trans Am. Why won't 3.73's work with it though? I mean the restrictive TPI intake is gone. I figure on stock 2.73's I wouldn't like my bottom end very much, it already feels torqueless down low. Only when it's cold will it spin the tires. So I thought with the extra 600rpm of easy breathing, the shorter gears will compliment it nicely.

So should I go with the LT1's cam as well?

Won't the 3.73's pick my lowend back up?

 

hummm... i guess it does have the L98 cam.

well with the TPI fully ported, your peak should be around 5000-5500rpms. i would say 3.73's would work good. they seem to be nice for super ram 350's making peak power up around 5500rpms on autos. First gear is pretty quick but the rest is a good match.

LT1 cam is mild as the L98. i would step up just abit higher with alittle more duration and lift. around .480-.500 to get close to peak flow on your heads. Lt1 intake tho is gonna give you ability to breathe at really high rpms. like 6000-6500rpms if the rest of the components is there. Torque in the low end will be lost, so i would say 3.73's are perfect for the LT1 intake.

 

I'm doing just that.
I've got a lt1 intake, and a 98ls1 rear w/3.73's. Still waiting to put it all together though...i don't have a garage, so i only get to work on it when the weather is nice at night.

 

I went from 3.23 gears to 3.73 gears in my 88 Formula 305 TPI Auto and cut half a second off of my ET and gained 3mph in the 1/4. Car was much much quicker in all gears with the 3.73's and I still could hit 140mph.

Now I did put a T5 into the car and that dropped my top speed to about 130mph, but the car is a lot more fun to drive.
I also put a Holley Stealthram on the car recently and I did notice a loss of low end torque but the car will pull to 5K instead of falling on it's face at 4500rpm.

 

Just get the 3.73s and be done with it. To get that motor to run good, you will need an LT1 intake with a matching hi rpm cam and a bunch of misc. parts to make it work. After that, I stil don't think it will be close to stock LT1 HP. Just find yourself a nice LT1/4L60E combo and swap it in.

 

I never said I wanted LT1 hp out of my car. I wanted to know if 3.73's and the Lt1/L99 intake would work well with eachother.