I have a 388 lt1 forged bottom end and using a flat top -5cc forged piston built for nitrous. Im also using AFR 210 heads that were also max ported. Lt4 intake and LT headers, bullet, dump. Backed by a th400 trans and a 4.10 gear on 28s.
I will be using a 250 shot minimum and would like to know what the hardcore guys recommend for this setup!

Going with a 4000 stall
This is the cam Im told to go with, 244/252 .640/.640 110 LSA HR cam.

Does this sound good and what do you think it can do

 

too much gear.

 

really explain why please?

 

diminishing returns. in a car that quick it will be a much easier car to tune if its not blowing the tires off or on the bumper. i would assume that combo would make 7-800+ rwhp, and if thats the case, you will not miss the extra gear. also, unless your planning on an aftermarket management, you will be out of gear long before the traps.

imo, of course.

 

You will obviously need to change your springs from the SR ones you have now to run that HR cam, and probably put less gear in it too like stated...or preferably go to aftermarket engine management. In theory you should be able to get around 135-140mph trap out of that setup @ 7krpms, which is around what an 800 hp fourth gen should trap, but I think you will run out of rpms before that in the "real world".

Either way it will be too close for comfort IMO. If you have an OBDII computer then you get an extra 200 or so rpms and may be able to make it work.

**edit**
Have you even calculated your RPM in every gear yet, or compared your final drives/speed/rpms with different transmission/rear end combinations? Making sure to factor in the rpm limits you are working with and the cam size you want to run, you don't have too much room to work with. If your big cam peaks at say 6700 rpms with your killer high flowing heads, and you have tons of gearing...but only a 7K rpm redline, you wont have much room to test and adjust your shift points.

There are a lot of things that need to work together in a build of that caliber. I would be talking this over closely with a professional instead of asking online for opinions - when you get to this level of a build you don't want to be guessing, taking opinions from Joe Blow, or even worse - using trial and error.

 

NO I havent calculated anything yet due to the build being nowhere done. I already have the springs for the HR setup and will just run this and then in the latter of the year I can switch to a SR. The setup I will switch and move on to a vic. jr intake/efi setup. But as for now I have everything to get this thing going except the cam. How else can I determine what gear I need and what to do. To my calculations I was told already and have seen other cars with similar setups run the same combo. SO I dont see why this setup wont or cant work right?

 

with a 250+ shot on a 388 with big heads i would think you could run 145-150+ mph.
if you are running a big tire with wheelie bars you can put whatever gear you want in there.

 

NO wheelie bars at all! I have a nice kit im going with and a progressive controller to control the nitrous coming in. SO I can pretty much leave soft (on motor) and ride it with it coming on.

So would I be better off with a 3.73 then? I dont see the problem with my gear?

 

www.f-body.org/gears
This has helped me a ton over the years.

 

you can make it work with the progressive. figure a ramp over 1.2 secs or more. solenoids need to have teflon plungers so they'll last awhile. you still need to get it through the traps under 7k unless you have an aftermarket management deal.

what do you have done to the chassis of the car? if it isnt fully setup with all the suspension goodies and some weight taken out you are wasting your money on all this engine stuff.

 

car will weigh under 3200 lbs with me in it. IT has full suspension, tube everything, DA shocks on all 4 corners with 275 front springs. Progressive I have, but a stock 96 pcm good to 7200 rpm.

Now do you think I would be better off with these heads or some AI200cc heads? I want this to all work right and not be a flop.

 

i would go with the afr's. check with t.e.a about getting them ported. your car should run somewhere around 150mph with a 250 shot being the minimum. i think you have too much gear still. remember converter slip when you are trying to come up with a gear ratio.

 

The heads are already max ported. So your saying with a 4000 stall I should go with a 3.90 or higher gear?

Also where do you figure out what I should mph?
I dont get that,lol

 

with a full suspension car that weighs 3200 and has 7-800rwhp on the bottle, how fast do you suppose the car should go?

what does the car run now?

 

I'd do a 3.70 max, maybe a 3.55. The car's going to be lazy on motor with that cam/gear/n2o converter regardless. A 3.90 and a 30" radial would be better, but that's gonna take some cutting to fit.

 

this man is correct.
wicked, im running a continental converter as well....

im going from a 3.89 to a 3.75 ratio in the coming weeks. im on a 28" radial, but i dont expect to go but around 145ish when i take it to the 1/4mi. track again.

 

Car dont run yet, it will have its first time out next year

Well then should I run a 26" tire instead? If its going to be a pig n/a then I could just stick with a 3.42 or 3.55 gear with a 28 or a 3.73ish with a 26.

 

forget about n/a. you have 3 possibilites:

bleh running car on and off the bottle
good running car off the bottle, slow on the bottle
good running car on the bottle, slow off the bottle

 

good running car on the bottle, slow off the bottle

how much slower will it be?

 

As soon as my crank trigger comes in, we'll see how the converter does

Trust me, you're going to want as much tire on that car as possible. Bigger tire = more consistent = not having to risk putting it on the bumper just to get it to hook. There's a reason outlaw 8.5 classes are fun to watch