Builder

Hi Folks,

Have picked up an LT1 block to rebuild for the Impala SS. Thinking about a forged, solid-roller with moderate bore/stroke (a 377) and a 2-bar ProCharger, ported intake and heads with Jesel shafts to turn 6-6.5k.

Can the LT1 bore to 4.155? Was looking for the info with search; couldn't find the answer. Sorry if a repeat...

TwoFast4Lv

iTrader: (8)

Not with out sleeving all the cylinders Iwas going to do this a while back but changed my mind. Price was $$$$

Builder

So, just 30 or 60 over is the max?

OutlawZ

iTrader: (4)

I believe a 409 was the biggest LT1 I have ever seen as far as displacement.... I forgot what the bore and stroke was but yeah it was like a 3.875" stroke and like a pretty large overbore... actually i think the stroke was bigger than 3.875 cause that combined with a .030 would give you a 396.... I don't think another .030 (.060 total) would give you another 13 cubic inches.....

But a 409 LT1 was the biggest i've heard in an impala... at that point you can't use it in most power adder setups cuz the cylinder walls are too think at that point.... the guy that did it was an NA Impala that ran pretty hard...

30thZ28

iTrader: (1)

I have a 410 ci LT1, def. the biggest you can go. But the torque should be nasty, The cylinder walls def. would be to thin at that point for sure, that's why i'm going the nitrous route. And the price it cost to build probably really doesn't justify it.

OutlawZ

iTrader: (4)

You think you have enough cylinder walls left for even nitrous????? 410 must be a huge overbore......

TwoFast4Lv

iTrader: (8)

actually I have seen 421s but they never seemed to last long

4.090 bore x 4.00 stroke

urbanhunter44

iTrader: (1)

Yeah I've heard of 421s. Imo if you're stroking it just go with a 383 and be happy.

TwoFast4Lv

iTrader: (8)

pretty much. getting a head to support extra cubes is a PITA

MrBill97396

iTrader: (10)

Take it .60 over and run her till she blows, get a great set of heads done by LE or AI. Let them know what your plans are and I bet you a dollar they can make it happen for you.

engineermike

I'm .060" and running 20 psi boost. Gone 143 mph in the quarter at full weight + cage + turbo + intercooler = pig. Also had an overboost incident that severely blew both head gaskets and still no block problems. My guess is 25 - 30 psi, maybe more.

Mike

MrBill97396

iTrader: (10)

Exactly, it is safe. Block failure should not be an issue, just make sure there is no oil pan failure

30thZ28

iTrader: (1)

I've personally seen LS1's running 427s but never seen anything bigger than my 410 in an LT1, anyone know why you can go larger with the LS1???

harvickgm

iTrader: (10)

LS1 blocks are sleeved.. they just change the sleeves to what bore size..... it is rather nice idea...

TwoFast4Lv

iTrader: (8)

well that and the extra deck Hieght makes them more stable with more stroke. No cam to rod issues or any thing with a LSx base!

racer7088

A 4.000 inch crank will go in with the right parts and is a good NA engine but the pistons are somewhat short for a power adder. I am doing some 408 inch LT1s at 4.030 bore like that. I wouldn't go to a 4.060 initially but a lot of people do after several rebuilds or because they had to and they don't seem to have many problems. It also depends on what pistons are available on the shelf if you are trying to stay on a budget.

Builder

Thanks for all the feedback. Sounds like the max bore/stroke is 4.060 x 4.00. This comes out to 414.28 by my calculations.

I am going to go .030" over to start and stay with the stock crank. The other engine will get a 3.75" crank and .030 over to make a 383.

Rickys S/C Z28

iTrader: (13)

how much does it cost to bulid a 383 or a 396???

racer7088

only a little more in general and the 396 is a little more than the 383 but it totally depends on eth parts used and what you do as far as splayed caps etc.

OutlawZ

iTrader: (4)

Yeah I was gonna say the same thing..... 383 or 396 can cost you as little as like 4K if you get a budget stroker kit. If you go full blown with splayed mains and all the right parts then it'll run you about 15K....

I've got about 13K in my 383..... there wasn't any reason to go 396 so i didn't....