View Full Version : Engine Displacement Question
22lambo
09-16-2009, 10:37 PM
What makes a 350 a 355 or 383 or 396? Do you have to bore out the engine for that or just get a stroker kit? Thanks.
Z28pr0jekt
09-17-2009, 12:13 AM
here's the skinny on LT1 buildups.... it all depends what you're looking for. there are quite a few non stroked NASTY LT1's out there in the 355 cubic inch variety as well so depending on your budget don't get super dedicated to having to stroke it....
355 ci LT1:
Bore: 4.030 (.030 overbore with an .030 oversize piston)
stroke: 3.50 (stock stroke)
rod length: 5.7", 5.85", 6"
notes: 355's don't get the additional torque of a stroker motor. upped compression for more power is almost a must. Also a 6" rod 355 has one of the best piston/rod ratio in the game. more dwell time at TDC, more complete burn will usually result in more power. Try to get compression up to about 11.5:1 to 11.75:1. Will still run on pump gas at those levels. Good heads/intake also a good idea... you can use the stock crank but I would at least 2 bolt stud the main caps while you're down there.... good quality h-beam rod as well for bottom end stability.
383 ci LT1:
Bore: 4.030 (same as above)
Stroke: 3.75"
Rods: usually 5.85 or 6"....
notes: 383's will get the added torque from the increased stroke. same deal with compression as a 355. Definitely get a good forged crank as well as rods and pistons. Lunati, SCAT, or Eagle at a minimum. Block clearancing is required for rod bolt clearance but it's pretty minor and any competent shop can do it....
396 ci LT1:
Bore 4.030 (same)
Stroke: 3.875"
Rods: i've only seen 5.85's
notes: again more torque from more cubes and more stroke. block requires alot of clearancing and be careful because you don't want engine man to cut into a water jacket reducing block to garbage. with custom work i think you could use a longer rod possibly but not advisable... i have limited experience with 396's.... i personally like the 383 route since you can always clearance more later if you want the 396 and 13 ci isn't a whole **** ton of an increase....
hope that helps
22lambo
09-17-2009, 12:17 AM
Thanks a lot! That finally answered my biggest questions. So a 355 is pretty much a engine that is bored out a bit?
96LT1355Z28
09-17-2009, 03:29 AM
Thanks a lot! That finally answered my biggest questions. So a 355 is pretty much a engine that is bored out a bit?
Correct stock engine bored .030 over! According to OutlawZ's post we have a 3.50 stroke, I thought we had a 3.48 now I'm confused!?:hmm:
22lambo
09-17-2009, 07:15 PM
Correct stock engine bored .030 over! According to OutlawZ's post we have a 3.50 stroke, I thought we had a 3.48 now I'm confused!?:hmm:
So either way if you want more displacement then you need to do machine work, right? Well looks like I will need to save up some money and for the stroker lol
popo8
09-17-2009, 08:31 PM
Ok, let me add on you question if I may....
my car was a 383 which is Bore: 4.030 Stroke: 3.75" Rods: usually 5.85 or 6"....
if I went another .10 over.... does that make it the 388 that I am guessing it is???
96LT1355Z28
09-17-2009, 09:46 PM
I found this,it might help:
http://www.csgnetwork.com/cubicinchdispcalc.html
As far as changing rod legnth affecting displacement I guess that would all depend on the compression distance of the piston used.:hmm: A recent Car Craft had an article on strokers and it showed all the various combo's and what parts you need to achieve them but I can't find it on their site!
"So either way if you want more displacement then you need to do machine work, right? Well looks like I will need to save up some money and for the stroker lol"
If you want more dispalcement you'll have to have machine work done. Keep in mind strokers don't necessarily make more power, they just make it at a lower rpm. Which is why many like a 383 on the street vs. a 355.
Captain Dirtymax
12-16-2009, 10:30 PM
Correct stock engine bored .030 over! According to OutlawZ's post we have a 3.50 stroke, I thought we had a 3.48 now I'm confused!?:hmm:
350's (and 305's) all had a stroke of 3.48". the engine would be a 351 with a 3.5" stroke ;)
popo8
12-16-2009, 10:50 PM
Ok, let me add on you question if I may....
my car was a 383 which is Bore: 4.030 Stroke: 3.75" Rods: usually 5.85 or 6"....
if I went another .10 over.... does that make it the 388 that I am guessing it is???
ok, answer me now.... please???
Captain Dirtymax
12-16-2009, 11:03 PM
do you mean .010 over the 4.030 or .10 over the 4.030???
4.040 bore and 3.75 stroke nets a 385
4.130 bore and 3.75 stroke nets a 401, but you're not gonna find a factory 350 casting that can safely go anywhere NEAR 4.130 bore. the cylinder walls will get too thin.
or are you talking about another .10" on the stroke???
popo8
12-16-2009, 11:05 PM
well my 383 wouldve been .30 over right...?
so now my XXX is that original .30 over plus another .10 over...
Captain Dirtymax
12-16-2009, 11:10 PM
your 383 would be .030 over, or thirty thousands. you're typing it like three tenths. ;)
your 383 bored .010" over would be a 385
popo8
12-16-2009, 11:34 PM
your 383 would be .030 over, or thirty thousands. you're typing it like three tenths. ;)
your 383 bored .010" over would be a 385
ok, sorry excuse my decimil point...
my question is why is a 350 that is 10over a 355 (increase of 5 ci)
but a 383 with an additional 10over only a 385 (increase of 2 ci)
????
Captain Dirtymax
12-16-2009, 11:39 PM
i honestly don't know.
it's just like a 396ci stroker is 4.030' bore and 3.875' stroke and a 408ci is 4.030' bore and 4" stroke
the 396ci has a .125" shorter stroke, but is only 12ci smaller
popo8
12-16-2009, 11:42 PM
Yeah, I am absolutly lost... I will take your word for it... but then I have been misrepresenting my motor as a 388 after the 383 broke.....
To clear the air EVERYONE my motor is a 385ci (I think????)
lt1truck
12-17-2009, 12:15 AM
ok, sorry excuse my decimil point...
my question is why is a 350 that is 10over a 355 (increase of 5 ci)
but a 383 with an additional 10over only a 385 (increase of 2 ci)
????
i think a 350 .010 over would be like a 351 or 352 or something, to get a 355 you have to bore .030 over
popo8
12-17-2009, 07:56 AM
i think a 350 .010 over would be like a 351 or 352 or something, to get a 355 you have to bore .030 over
Ok... Im just getting more and more confused....
speedracer2536
12-17-2009, 01:23 PM
a 355 is .010 over not .030
Fastbird
12-17-2009, 01:53 PM
a 355 is .010 over not .030
Wrong. 4.030 x PiR2 x 3.48 x 8 = 354.935 C.I.D.
Simple math guys.
lt1truck
12-17-2009, 08:21 PM
so im right..........Right?
1963SS
12-17-2009, 08:46 PM
This is all too confusing. Are we measuring the volume of a cylinder and then multiplying by 8? The volume would also include the head gasket thickness.....wouldn't it?? After we get the volume using pi, radius squared, and the stroke should the head gasket thickness be added in as well. You know, something like 3.14 x 2.030 squared x .050? I've never, ever thought of that before.:disagree: That would add about 2 1/2 cubic inches to the engine. Right??? How's about the 2 1/2 thousandths bearing clearance. Do you add or subtract it.
Captain Dirtymax
12-17-2009, 09:41 PM
so im right..........Right?
yes.
speedracer is wrong.
Z28pr0jekt
12-17-2009, 09:45 PM
This is all too confusing. Are we measuring the volume of a cylinder and then multiplying by 8? The volume would also include the head gasket thickness.....wouldn't it?? After we get the volume using pi, radius squared, and the stroke should the head gasket thickness be added in as well. You know, something like 3.14 x 2.030 squared x .050? I've never, ever thought of that before.:disagree: That would add about 2 1/2 cubic inches to the engine. Right??? How's about the 2 1/2 thousandths bearing clearance. Do you add or subtract it.
bottom end determines motor size, not heads or head gaskets. Cylinder size and stroke are the important parts
Fastbird
12-17-2009, 09:50 PM
bottom end determines motor size, not heads or head gaskets. Cylinder size and stroke are the important parts
Bingo. The question about head gasket thickness figured into quench and compression ratio.
A quick displacement breakdown for LT1's (all numbers rounded):
Stock 4.00 x 3.48 = 349.67 (350)
4.010 x 3.48 = 351.42 (351)
4.020 x 3.48 = 353.17 (353)
4.030 x 3.48 = 354.93 (355)
4.040 x 3.48 = 356.69 (357)
4.050 x 3.48 = 358.46 (358)
4.060 x 3.48 = 360.23 (360) ** Would NOT recommend going over .060 on an LT1.
3.75 Stroke's:
4.010 = 378.68 (379)
4.020 = 380.57 (381)
4.030 = 382.47 (383 though rounded it's a 382)
4.040 = 384.37 (384)
4.050 = 386.27 (386)
4.060 = 388.18 (388)
3.875 Stroke's:
4.010 = 391.30 (391)
4.020 = 393.26 (393)
4.030 = 395.22 (395 though commonly referred to as a 396)
4.040 = 397.18 (397)
4.050 = 399.15 (399)
4.060 = 401.12 (401)
Hope this helps clear up some questions and can be referenced in the future.
1963SS
12-17-2009, 09:55 PM
:)I was just teasing a little.
Captain Dirtymax
12-18-2009, 01:22 AM
can the LT1's be taken out to a 408??? i know Gen I blocks can (with some clearancing for the rods and crank to spin), but i never did look into the LTx's for that.
lt1truck
12-18-2009, 02:14 AM
seems like it would take alot of stroke and super thin cyl walls to go 408. plus would the rods run into the cam? do they make a super small base circle cam to clear the rods???
Captain Dirtymax
12-18-2009, 09:37 AM
a 408 is only a 4.030" bore with a 4" stroke. i know that you can have a custom grind to get the smaller in base circle on the cam for it to clear, but even then you're limited to 220 degrees of duration or the rods will strike a lobe.
Fastbird
12-18-2009, 10:31 AM
Thing is I don't know if a 4" stroke would fit in an LT1. There's a LOT of clearancing needed to make a 3.875 stroke fit.....granted it's only .125" more but that could easily break into the coolant jackets with that extra clearancing needed.
popo8
12-18-2009, 04:07 PM
Bingo. The question about head gasket thickness figured into quench and compression ratio.
A quick displacement breakdown for LT1's (all numbers rounded):
Stock 4.00 x 3.48 = 349.67 (350)
4.010 x 3.48 = 351.42 (351)
4.020 x 3.48 = 353.17 (353)
4.030 x 3.48 = 354.93 (355)
4.040 x 3.48 = 356.69 (357)
4.050 x 3.48 = 358.46 (358)
4.060 x 3.48 = 360.23 (360) ** Would NOT recommend going over .060 on an LT1.
3.75 Stroke's:
4.010 = 378.68 (379)
4.020 = 380.57 (381)
4.030 = 382.47 (383 though rounded it's a 382)
4.040 = 384.37 (384)
4.050 = 386.27 (386)
4.060 = 388.18 (388)
3.875 Stroke's:
4.010 = 391.30 (391)
4.020 = 393.26 (393)
4.030 = 395.22 (395 though commonly referred to as a 396)
4.040 = 397.18 (397)
4.050 = 399.15 (399)
4.060 = 401.12 (401)
Hope this helps clear up some questions and can be referenced in the future.
YES.... thankyou Fast bird....:metal:
Captain Dirtymax
12-19-2009, 01:55 AM
Thing is I don't know if a 4" stroke would fit in an LT1. There's a LOT of clearancing needed to make a 3.875 stroke fit.....granted it's only .125" more but that could easily break into the coolant jackets with that extra clearancing needed.
so i'm guessing the LTx blocks aren't quite the same as the Gen I SBC???
because i KNOW the Gen I blocks can support a 4" stroke crankshaft (with clearancing)
Spartan7
12-19-2009, 05:29 PM
because i KNOW the Gen I blocks can support a 4" stroke crankshaft (with clearancing)
Yes, it's been done. There are a couple 408 LT1's on LS1tech, and I think I remember seeing a 410.
EDIT: Yea, here it is:
http://www.ls1tech.com/forums/lt1-lt4-modifications/1182998-fresh-410-stroker-lt1-vid.html
jakesz28
12-23-2009, 08:06 PM
so i'm guessing the LTx blocks aren't quite the same as the Gen I SBC???
because i KNOW the Gen I blocks can support a 4" stroke crankshaft (with clearancing)
Not all of the production gen 1 motors can handle a 4" stroke witout breaking into the water jackets and aftermarket blocks are a different animal. Aftermarket blocks are cast thicker and you could build a 450" small block if you went with an aftermarket tall deck block.
Captain Dirtymax
12-25-2009, 04:34 PM
i meant Gen I's in general, i knew that not ALL of them could be clearanced enough.
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