Maedgo

hay guys, i need a little help. i am building a 355 and with the parts i have the CR was going to come out to be around 11:1 Is this too high of a compression for a fun daily driver? if so what should it be? here is what i have

scat cast crank, 3.480 stroke
forged i-rods 5.700
KB forged pistons -4.8cc bore .030
stock proted heads
i am using the hotcam with 1.7rr and 918 springs

i do not know the gasket thickness yet or the deckhight, all that can change as of now because the block is at the machine shop and the machinest thinks 11: 1 is too high and wont start on it yet untill i make sure that is what i want to do. IF what i have will be fine what gasket should i use? and what deck hight should i have? also if i have to i can change pistons to give me the correct CR. The car is a 94 Z28 A4 and i am going to go with a 3000 stall, and i will get the proper tuning. the best pump gas i can get is 93

LameRandomName

Just curious...
Any particular reason for that decision?

Maedgo

for more lift, i have to buy rockers anyway, they are not comming with the kit i am buying from a friend.

Injuneer

Since you're asking about an LT1, you need to post on "LT1/LT4 Engine Tech"..... not on Advanced TEch. I'll move it for you.

11.1:1 shouldn't be a problem with that setup.

96capricemgr

Sounds like your machinist knows nothing about the LT1. Stock your motor was 10.4, the LT4 was 10.8, 11.0 is easily doable.

LT1inaMGB

The engine I am assembling now has been decked so the piston is .010" down in the hole, the chambers are 56.9 cc and the valve indents are 5 cc. I am using a .026" Mr Gasket head gasket which gives me an 11.3 ratio. More importantly, the quench area is .036" (about as close as you should go) and that is what allows you you to run higher compression without detonation. I will be running 91 octane and don't anticipate any problems. People sometimes add gasket thickness in an attempt to reduce detonation but it often makes the problem even the with lower compressin ratio because it widens the quench distance. If the same engine had a tighter quench it might not detonate even with higher compression ratio. Seems counter intuitive but it works.

Maedgo

What gaskets should i go with? any brand or type better? any part numbers? thanks for the info guys

LT1inaMGB

Depends on the rest of your setup. They are all different thicknesses.

Maedgo

what else do i need to know?

LT1inaMGB

You have an email.

Jim

1racerdude

The static ain't s***,the DCR is what counts. Ya want 8.5-9 DCR with .035-.040 quinch to make it run right and not detonate.This is all cam dependant.