ohplz

ok heres something im curious on...

im gonna forge the bottom end to aim for 800+rwhp by adding a MPT78 or a TC78...

i was going to get 317 heads + -8cc diamond pistons etc etc
but i hear u can get -25cc dish pistons, + 243 or standard 241 heads (+springs and rods )

whats the better choice? im not going to be running 20 psi or anything ( so i guess? )

but i want to hit 800+rwhp....

can someone explain the pros cons etc... or anything else i should expect etc?

longrange4u

iTrader: (2)

Compression Compression... it directly affects the boost you can run without detonation depending on your gas. If you plan to run pump-gas... I would say go with the -25cc dish pistons. What cc chamber heads are you going with? What size motor is this? 408?

The Fugitive

iTrader: (6)

does compression affect drivabilitiy? Is a lower compression better on gas or is highter better?

extremetoy

iTrader: (17)

sounds like either way it would be the same compression ratio but hes wondering if it would be better to have more dish in the the piston or in the head... ive heard it would be better to have the deeper dish pistons but have no expierence

longrange4u

iTrader: (2)

Hold on fellas... Compression can affect driveability if you lower it too much. Lower compression motor makes less HP but can handle more boost.... Detonation will destroy your motor.... so you dont want that. A street driven boosted motor that you are going to run pumpgas into... (IN MY OPINION) should be below 9:1 Compression ratio... So...

To help you answe these questions you have you have to give us more info... What size motor? How do you drive it? Daily? Semi-Street? Track only? What are your HP goals? What fuel are you going to run?

ohplz

ok ls1 (forged 346)
daily driver / some track...
800+rwhp would be nice
241 heads with 918 comp springs + manley rods ( standard length )
( im at 500rwhp at the moment on standard bottom end + springs / rods / turbo cam / twin fuel pump set up / exaust etc )
we have 98 octane over here... ( australia )

i want something that is reliable etc... im new to the internals of ls1's.. so its learning whats " best for me "...

longrange4u

iTrader: (2)

Nice setup... if your going to run 98 octane I would say shoot for a ~9:1 compression. Keeps the HP#'s up on your motor but gives you breathing room with boost. I dont know what CC Chamber heads the 241's are... but if they are ~65cc then I would say go with the -25cc dish pistons. There are alot of better folks on here to ask (alot of sponsors that build motors) then me... but this should get you started.

Do a search for "what compression ratio" and you will find alot... read 10x buy once!

ohplz

well who could i ask thats a forum sponsor about that setup etc? i dont know any of the sponsors here....

longrange4u

iTrader: (2)

Wow... any of them. Use the search tool and read some about compression. Wait through tomorrow and alot of guys that know better should post up here. I knew nothing about this stuff 7 or so years ago... I have learned tons from the guys here online.

Bottom line on your setup.... Google a "LS1 Compression Calculator" and fill out the stats... you can play with the different CC chamber heads, Pistons, gaskets... giving you different compression ratios. If your going to run 98 Octane I say shoot for 9:1 to be safe and it will give you room to turn up the boost

The Fugitive

iTrader: (6)

wow thanks for the info but with the calculator how do u know the size of the head gaskets (trial & error?) I'm going to see if they have one for the other ls motors

chuntington101

is the the Gen-T kit???

Chris.

ohplz

yeah man, was the base gen-t kit, with extra mods to get more out of it...

im going the next level... so want to get more info about it...

eviltwin_1987

iTrader: (18)

how much boost do you plan on running? Just wondering because i heard that you should always go double valve springs with the amount of boost you will need to make 800+hp

elias_799

iTrader: (8)

i personally would like to have a bigger combustion chamber 72cc and less dish to the piston. the smaller the combustion chamber the more you motor is likely to knock. that is why diesels have flat combustion chambers.

Big Bird WS6

iTrader: (9)

i know you said your opinion. but i live in iowa. we have e-85 at the pump. so that changes the hole pump gas thing. my e-85 pump gas is like 100 octane.

so with your knowelge i need help.

i want to run 1000 wheel horse with only using 18psi. on 2 turbos that push 65lb/min. i have a 377 ci motor. and my compression is around 9.3:1.

will it work or no?

thanks

Big Bird WS6

iTrader: (9)

so since i have the 225 afr with 72cc, that is good?

oh and i have -11 dish

The Fugitive

iTrader: (6)

if you want to know what compression to run try calling a sponsor, TexasSpeed can help I called them last week for some help on that.

Big Bird WS6

iTrader: (9)

^^^^ you want me to call a sponser in texas about running e-85?

do they have e-85 in texas?

and sorry if i was going ot call a sponsor about boost it wouldnt be texas speed. it would be like LG motorsports. or Jim at speed inc.

The Fugitive

iTrader: (6)

^^^big misunderstanding u can call tsp for questions bout compression they have a program for that to get u a good compression but I only used them as one example there are plenty of sponsors to help.

Jimmy P

iTrader: (177)

I ended up using -25cc pistons in one of my setups at first, and then when I wanted to raise the compression I had to mill the heads a lot. Dont lower the compression too much as it will make your drivability poor.