some basic FI q's
 

ive done a search and i seem to get mixed results on this. im building a forged ls1 and i havent decided for sure if im going with a F1 procharger or a decently large turbo. so im seeing i can pick up 317 heads for a good price on here and i have some people saying that 317's are great for FI but some are saying its not worth it. looking for some honest opinions from people who either have them or have seen this done. my build is getting expensive (79 corvette ls swap) on its own and if i can save some money by going with 317's and see great results id like to. aiming for 650+rwhp btw

it's a very common topic but instead of telling you to use the search feature, here goes.....the 317's can get you to over 1000rwhp. they're used primarily in budget builds or for those not looking to go all out with with high boost. most will say not to go much over 20psi with your typical ARP studs due to not having the thick deck but you can go a bit beyond that if you do 1/2" studs from what i've seen...like 23-25 lbs, but you're pushing your luck then. however, if you've got an extra $500 for the big studs and machine work to the block, i'd say you'd be better off going with a good set of aftermarket heads with standard ARP studs. you can also use 241's and 243's depending on what cr you are aiming for with whatever pistons you are running. the next most common reason for choosing the 317's is the larger chamber volume which for me personally, i'm doing to drop my cr on an existing motor as well as being on a tight budget. win win.

hope that helps.

My 317's have been great, no problems with them in 7 years. Check this thread out...
https://ls1tech.com/forums/forced-in...ide-w-vid.html

Is this a street car or a strip car build ?

well as far as comp ratio goes i honestly have no idea. that was going to be my next thread as far as what i should be aiming for. this will be a street car mostly and will see the strip only a few times a year. but mostly will be my weekend car/racer. if i get the 317's and port them what comp ratio would i be sitting at? im 90 % sure im going with the f1 procharger, and also not sure what comp ratio these things prefer

anywhere between 9:1 or these days 10:1 is used. I went 9:6. the lower you go, basically makes it safer for you to run pump gas. the 317's are a good bang for the buck....if they had a thick deck from the factory, there would be alot less people running the high dollar ones. the main thing is good gaskets and some studs. and as always the tune. better safe than sorry.

Well it looks like ill go with the 317's. Its not a budget build but it just means I buy my procharger quicker, plus with this being an ls swap into a 79 vette I need to spend money on other areas as well. OK so time for another dumb question, how do I lower the comp ratio of the 317's or should I just leave em be. My goal is settled on 650rwhp. Also on that note is the f1 too much for this or will the d1 do the job. My thinking is I could do the f1 and run lower boost and be more in the clear rather than run the d1 on higher boost and risk cracking the ls1 block. At least this is my thinking feel free to correct me if I'm wrong I'm new to forced induction and this is my first build

To lower the compression ratio in the heads you would have to have the combustion chamber size increased. In keeping cost down, I'd leave the heads as is and reduce the compression ratio with the pistons, and shoot for a 9.5/1 compression ratio. If the compression ratio ends up a little higher it won't hurt anything, as 650 rwhp is not very high. If you don't think you'll ever want much more power than 650 rwhp, the D-1SC would work just fine. Power is contagious though... Bob