bca21

I have a ls1 short block with 25,xxx miles on it and the original plan 4.00 inch crank, high compression 408 with a nice set of heads/cam and fsat intake. I decided to do lower compresion for forced induction.

Depending on what deals i can find, it will either be a single 91s or bigger or twin 70s.. Looking for around 1000 rwhp and 950 tq. What all does the short block need to handle a 1000 hp+? I no that a lunnati 4inch crank, manley boost pistons and rods will get it done but should the block be filled or should it be alright?

My questin isnt about the setup or how fast it will run ext.. I want to no what all needs to be done to the ls1 short block to handle a 1000+ down the road. Its not a daily driver but looking for solid 9.3s at 150 threw a glide and 7k rpm.. Any links would be great. remember, Im going from a 60mm turbod 04 mustang gt to a 408 with twins so im a little new with the lsxs

DONAIMIAN

iTrader: (18)

9.3's can be had with less power, and less turbo. I also would'nt wrap the motor out to 7k with a 4inch crank and 1k hp and expect any kind of reliability.

bca21

I was thinking the same thing, a 370ci ls1 with nice h/c/i with twin 60 with a .68a/r it should spool decent and pull up top. I just always wanted to build something big...

slp--firehawk

lol, go big then!! the only problem here is that you said 9.3 when you should have said 8's

a98ws6

iTrader: (48)

Look in the F.I. section for more help on this. They will be able to help you better.

JonCR96Z

iTrader: (33)

I think you'll have more problems with the car than with the motor if low 9s is your goal. I mean that's a good 650rwhp in an f-body.

bca21

Im being realistic considering the car is driven alot but i dont want to shoot to high..Ive seen twin 60s run low 9s and twin 76s runing the same... Just trying to get a ball park..

BIG BAD BLACKSS

iTrader: (4)

The LS1 block will deform at that power level. You need to go Iron block like I did or if you want to stay aluminum and get the parts needed for the conversion you can run an LS2 block an dits said to hold almost as much as the iron block.

If you go iron block everything bolts right up excpet you will have to drill/tap one accesory bolt hole on the front, and one is just flat missing. The one that is missing shouldnt effect you at all, the procharger uses that hole as one of 3 bolts taht hodl the head units, and even with it missing and that big blower there are no problems. So just a couple accesories is no problem what so ever.

Goldfinger911

iTrader: (24)

1000whp LS1? Is that even doable? An engineer from Lunati said once in an artilcle in GMHTP that the LS1 blocks limits were in the 900-1000 crank hp range. Nelson (NRE) uses the LSX block exclusivly for the 4 digit HP packages. I am just curious if it has been done with an LS1 block.

JonCR96Z

iTrader: (33)

A 408 isn't doable from an LS1 block anyway, so he is probably going iron 6.0.

sciff5

iTrader: (1)

I'm sure its been done. Its just a matter of how much water its pushing while doing it.

99blancoSS

iTrader: (115)

If your truely lookiong for 1000 rwhp your better off selling your ls1 shortblock as is and starting off with an LQ9 build. Then you can hit your mark maybe with TT APS system w but you need to figure how much boost you will need and then take into consideration the limit of the 4 bolt heads... So if your pushing 22-25 lbs your on the edge and pushing water.

hlaalu

iTrader: (3)

sounds like thats going to be a sweet build

Grimes

iTrader: (3)

Don't wanna be a downer, but a project like this takes some big, big cash. If you really are aiming for a 1000hp car that can be run on the street a good bit, I see you burning way past $20k very easily once you add stuff up.

bca21

See i didnt no about the ls1's pushing water. I know what it takes to build a 1000+rwhp. I no for a fact a 408 can push past 1000. Theres twin turbod mustangs making 1000+ but its take alot of boost and big turbos, but they dont have a problem with water; the stock mustand 281 block is rated at 1500 hp(block not s/b)

Not knocking but i couldnt imaging spending the money on any pre built kit, remember this is in a 04 mustang gt, different suspesnion so there kits different. We built the t70 on my car now, and recently did twin 60s on a 99 gt. Bith dont make as neer the same amount of power boost for boost, thats why i wanted a big power ls1. Makes me want to build a high compression nitrous 408 to save the hassle lol

GMCHammer

iTrader: (4)

That is the way I would go!!

odarabla

iTrader: (1)

You cannot build a 408ci out of a stock LS1 Aluminum block without resleeving the block. The biggest I've ever seen was a 396ci and that’s pushing the limits of an LS1. Now as mentioned above you can go iron block and achieve your goal of a 408ci. If you want to make big power build a 414ci 6.0iron block with 4.125 bore and 4.25 stroke with a decent FI cam use a set of the Trick flow 235CNC heads and you'll be in business for some real power.. The thing about the LS1 is you’re restricted to the smaller bore size of 3.90.

odarabla

iTrader: (1)

I don't know everything about Ford but I know enough to say that a 281ci stock aluminum GT block cannot handle anything near 1500hp. You would be lucky to get 500rwhp out of that block. Now the 03/04 Cobra iron block can handle in the upwards of 1000hp but that still is pushing the limits of the block. You are not going to build a 408ci out of a 281ci or a 302ci. The biggest you can go with a 281 is around 330ci, the biggest out of the 302 is 376ci if you use a Dart block. You can build a 408 out of a iron block 351 with ease but I still think 1500hp would really be pushing the limits of that motor. If you are looking to produce that much power and want to go with a LSX based motor I would have to recommend going with a LSX block from GM. That block is rated at 2500hp and you can build up to a 500+ci motor out of it.. Good luck on your build.

http://www.crateenginedepot.com/stor...FQwDGgodZVgnbQ

odarabla

iTrader: (1)

4.6L 281ci GT block are not iron thay are aluminum. The only years they made a iron 281ci block for a Mustang was 2003/2004 and that engine went into a cobra.

bca21

WOW did you not read any of the thread, first off im going to a lsx based motor...

And btw 4.6 block is iron not aluminum, I have a 04 mustang gt and that block is iron.

96-98 cobra is aluminum, 03/04 manual mach 1 is aluminum, all mustang gts until 05 and newer is iron.

And dont tell me a 281 iron block wont handle 1000+ hp. mmr is making 1600 rwhp on there twin turbod outlaw car. No one makes a aftermarket block btw for the mustangs, no dart dosnt have a block..



With money funds, I might have to go with a N/A iron 408...