so i have a 383 that i am building but i ran out of money fast so i wonder how much power i will be making through this set up and my times in the 1/4. the mods are in my sig but with maybe stock 243s and a ls6 intake and ported throttle body. the cam is in the 240s/250s with mid .600 lift. what do you guys think i will make at the wheels and what will my times be?

 

I think you will make 490 rwhp,and run 10.83 1/4 mile.

 

how well would tsp 2.5 5.3l heads work with this setup?

 

i have a 383 11.75 cr 242 250 620/620 110 +2 prc stg 1.0 heads ls6 intake full bolt on, th400 5200 stall stock rear 3.90 put down 375 rwhp, flat lined at 5400, i dont think you will be anywhere near 490 even with a manual, and those heads you are lookin at flow very similar to mine

 

Whats with the flatlining power at 5400??? That big of a cam wants WAY more rpms. You have a problem somewhere. Theres lots of guys hitting 400+ whp with stock cube ls1's. You have a th400 and your stall is going to be a dyno hp killer, but even then, you shouldn't be flattening at 5400!!!!

 

you have a problem i have a 383 and ms4 my car makes power all the way to 6500 on the pre dyno it had 447rwhp tuner said it will past the 480 when he is done tuning it!! i have to fix my exhaust leaks maf bank one 02 and fuel pump and i will go back for my 480

 

i have made a post on this forum, but its gone now for some reason, this is from mofbody, where i do most of my posting

when you guys made the swap, did you notice a significant drop in power? How much? What kind of stall are you using? I have an 8 inch 5200 in a th 400 and I think it is robbing me blind of power on the dyno. Old 346 motor 235/243 cam ported 243's ls6 intake full bolt ons 4k yank stall 4l60e. New motor 383 11.75 cr 242 250 cam ported 243's ls6 intake full boltons th400 8 inch 5200 stall. Old motor made 415 to the tire, new motor made 375 to the tire. I am down 40 horse right there, but we cant forget I put a bigger cam in, bigger motor in, and way more compression!!! I cant complain about the tune or how the car runs, but I mean damn that seams low. This was on the same dyno. I would think this new motor should make 40-50 more hp than the old. So there is a good 80 hp MIA. I am sure the tranny will eat some but damn, i think there is somethn else goin on here. I will take a couple pics here shortly ofthe graphs and post them. The intake will hold me back some, but it shouldnt loose power with the big motor, just not gain as much out of the motor. What do you guys think?? Graphs in a few minutes.

383
http://i752.photobucket.com/albums/x...383dyno005.jpg

locked converter old setup
http://i752.photobucket.com/albums/x...4/DSCN0932.jpg

unlocked old setup, tranny slipping, going out
http://i752.photobucket.com/albums/x...4/DSCN0931.jpg
the 367 was when is was cam only

the torque curve heads down bigtime on the new motor (top graph)

Old motor: 1.2 hp/in2
New motor: 0.98 hp/in2 with more compression and bigger cam

Let's say the new motor should have made only the same 1.2 hp/in2, you should have seen 460rwhp. That would mean you are seeing 18% more drivetrain loss with the new setup than the old.
I would say ignore it but since the track times got slower too it certainly seems like something is still up.

 

af was dead nuts, what else could be goin on here? I think there is somethn going on too, but everyone told me that dyno numbers dont mean ****, take it to the track. track times on street tires got slower(mid 12's intead of low 12's) but thats on streets so its hard to look at those times. trap speeds, were less than before 113 instead of 114,115. what do you think? are u guys running ol,cl sd or maf tunes?

 

sorry to sabatoge ur post, i just got frustrated with my numbers again

 

did you change the motor and rear and trans togther? if so there is alot to look at. who set the motor up? i would start with cam timing. valve train check and compession check

 

motor and trans went in together, rear was done a while ago. cam is degreed back 4 degrees, springs were used, but checked before put into new motor. pushrod lenght is correct, had to compensate for the morel linkbar lifters and stock casting heads. compression check, how do you check that, i know the combustion chamber, mls gasket thickness, valve relief, cam, so compression should be correct.

 

I am curently building a 383 because of a rod bearing problem. Was wondering what cam to go with? I was thinking of running a G5X2 but IDK. The car is full bolt on with stock port polish 202/160 heads. Any sugestions?

 

Your problem is the intake and tb and your converter!! get a 3600 stall and 410 gears your cam needs more air and the ls6 intake and tb is not enough get a fast intake 92mm or the new 102mm and why do you go with a huge stall?? do this changes an i guarantee you will get your 80hp

 

i know the intake and tb will hold me back. it will not cause a dead flatline though, just have lower numbers across the band, at least i dont think so. i have 3.90, so thats really close to a 4.10, 4.10 would be too much unless i went with a bigger tire. the stall is a tsi super 8 nitrous stall, it comes in a little over 4 grand, look at the graph, on the motor, the only time it will ever stall over that is on the tbrake. i went with this stall because it is built for a ton of nitrous and can handle the tbrake, which is what will happen in the future. everything you said is correct, but the car should not dead flatline in my opinion, just keep going at that slope to 6500+.

 

I think you have that flat line at 5000 because is when your intake becomes the problem a restriction!! at higher rpm the engine sucks more air and now your ls6 intake cant flow that much air so it becomes a horse power assassin!! and that is why you get a flat line at 5000rpm

 

Yup once the intake/tb is done flowing it will flatline. How could it increase in power, it cant make anymore vacuum bc it cant accelerate any more bc its out of oxygen.