454ci from a LS7 block???
03-01-2007, 11:22 AM
#41
Originally Posted by 52172
just buy the new iron LSX block which will go too 4.5 bore or somethin like that
4.250" is the supposed max bore on the LSX, and that's not leaving much room for anything else. 
03-04-2007, 01:25 PM
#42
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Originally Posted by Nasty N8
Reason for smaller 427 is with smaller stroke you will be able to rev the motor. And RPM makes power as well and it will be far more reliable. And reason for not using the LSX block is it is going to be huge and will cause fitment issues in most cars the haeds will start running into things...
Nate
Nate
03-04-2007, 01:42 PM
#43
Originally Posted by Beast96Z
You can't go 4.5" on the bore when you only have 4.4" bore spacing. You would make it "one" cylinder then. 4.250" is the supposed max bore on the LSX, and that's not leaving much room for anything else.
4.250" is the supposed max bore on the LSX, and that's not leaving much room for anything else.
03-04-2007, 02:08 PM
#44
FormerVendor
Actually it is a law of physics and is the reason that all racing engines are displacement limited.
From Formula One to Pro Stock to Latemodels displacement will always make you faster.
Now whether it is worth the money or is a diminishing return is certainly true but displacement is a primary factor in speed.
From Formula One to Pro Stock to Latemodels displacement will always make you faster.
Now whether it is worth the money or is a diminishing return is certainly true but displacement is a primary factor in speed.
Originally Posted by Sharpe
What I was saying is don't follow "there's no replacement for displacement" in blind dogma. It's a wonderful guideline, but not some sort of a law of physics. It would really suck if a smaller displacement car blew your big-inch car away on the street, and he paid half as much, you know? Take a look at what people are doing in the dyno thread. You don't want a bigger-inch motor making less power than a smaller displacement engine is all I was saying.
03-04-2007, 02:59 PM
#45
FormerVendor
Originally Posted by john_sblendorio
I am looking to build the engine with a hydraulic roller cam. What is the max rpm you can spin without floating the valves? I think the next barrier is the the 5,100 ipm piston speed?
03-04-2007, 03:26 PM
#46
FormerVendor
Originally Posted by racer7088
Usually about 7000 with steel valves and nice components and maybe 7500 with Ti valves.
03-04-2007, 07:44 PM
#51
FormerVendor
Originally Posted by INTMD8
Those #'s suprise me as we have many hyd roller turbo motors with steel valves that easily spin 7,500 on the dyno and have seen 7,700 on the track.
I've built several NA 9 second pump gas solid and hydraulic roller LS1s and they don't usuallt shift over 7K. With a sheet metal or carb manifold though they will make power further out there which is probably what you guys are doing. Just don't know how long that kind of stuff goes before eating parts. Most of the people I know that do it regularly go through valvesprings etc. as they are not as happy up there as people would like to think.
03-04-2007, 07:50 PM
#52
FormerVendor
Originally Posted by john_sblendorio
7,000 is what I was shooting for. It yeilds ~5,000ipm piston speed with a 4.25" stroke.
Piston speed is basically what creates your airflow and power just like a blower. Basically your shortblock is a blower and bigger is always better as well as making the power at more reliable rpm which is a double bonus. I have 4.000 inch stroke engines going 9s at 3500 pounds shifting under 7000 rpm so 4.250 is even better!
Basically you can make more hp inside the operating rpm range of a hydraulic roller with cubes as you don't HAVE to turn as high an rpm.
03-04-2007, 08:33 PM
#53
FormerVendor
Yeah, the turbocharged cars we do definitely seem to hang on alot longer with a relatively small amount of power drop-off above 7,000, with a stock composite intake manifold. (compared to a similar naturally aspirated combination).
Havn't seen any excessive valvetrain wear, (so far).
Havn't seen any excessive valvetrain wear, (so far).
Originally Posted by racer7088
You won't usually be making hp up there with the average hydraulic roller though and long runner manifolds. Also if you are turning 7500 for long you'll probably start tearing stuff up with steel valves. Can you do it? Yes but it's not a good idea to tell someone that wants a reliable street car that. With Ti valves you can easily turn another 500 rpm though. I guess you can run much less aggressive lobes as well but again that isn't usually good for power either.
I've built several NA 9 second pump gas solid and hydraulic roller LS1s and they don't usuallt shift over 7K. With a sheet metal or carb manifold though they will make power further out there which is probably what you guys are doing. Just don't know how long that kind of stuff goes before eating parts. Most of the people I know that do it regularly go through valvesprings etc. as they are not as happy up there as people would like to think.
I've built several NA 9 second pump gas solid and hydraulic roller LS1s and they don't usuallt shift over 7K. With a sheet metal or carb manifold though they will make power further out there which is probably what you guys are doing. Just don't know how long that kind of stuff goes before eating parts. Most of the people I know that do it regularly go through valvesprings etc. as they are not as happy up there as people would like to think.
