[twenty_below0]

I'm looking for opinions on why everyone goes 427 instead of 429 or 434 when building a Dart blocked 2650 equipped motor? The heads will be whatever is available builder is ordering all long block parts next week. Dart LSNext Pro block, Dart CCW crank, Oliver Rods, Diamond pistons, Total Seal rings, Hes suggesting Dart 12 degree 280's but I'm open to Mast, WCCH Brodix or Pro, FED or maybe RHS 6 bolt LS3 hybrids, whatever I can "get" in the next 6 weeks with similar quality and flow potential. Cam will be spec'd by Pat G or Matt with GPTuning once heads have been ordered and bore decided.
I have the basic understanding of everything and have read an unhealthy amount of posts learning from Duck and the others here who are wayyy smarter than I but what I haven't seen is 4" stroke with a bigger 4.155 bore. Goals are 1000whp on E70 with good street manners and reliability. ( I know everyone wants this right...LOL) Car is cruiser weekend warrior occasional strip pass for fun. All supporting mods are already on the car anticipating the Dart block upgrade.
Will the added bore help or hinder the build is there something I'm missing why others aren't running 4.135 or 4.155 with a 2650 ? I'd like to keep the shift RPM 7000 or less and 18-21psi of boost depending on bore.
Car has an FI interchiller, ZL1 lid with FI spacer reinforced brick, 1440 injectors, Fore bigger double pump system 10 supply/8 return, Fore fuel rails, Flex Fuel, LPE HX, 3 gallon under hood reservoir, EMP pump, 4.5" intake, 3" exhaust etc, Currently spinning the shit out of a race ported 1.9 and managing the heat issues which are always a concern so I kinda wanna ease the blower rpm back a bit and not spin the 2650 to 23-26k like I have been this one. Thank you for reading and I appreciate any feedback.

 

[Lt1z]

Any of the above will work. 427s are just more common since pistons are usually on the shelf for them and 4.125 leaves more meat in the sleeve for boost. On the aftermarket blocks I feel that 4.155 is still safe if you like but I would not go beyond that

 

[twenty_below0]

Thank you I appreciate the feedback!

 

[loweredd]

Yeah, 4.125" first leaves 1 or maybe 2 re-bores left in the block.

 

[Rubber Duck]

What size intake valve are you going to use?
How much horsepower are you after and at what engine RPM?

 

[random84]

From what little I've seen, the 2650 will probably be happiest around 17-18 psi. Think 9.5 / 3.0 pulley.

Sent from my SM-G991U1 using Tapatalk

 

[twenty_below0]

What size intake valve are you going to use?
How much horsepower are you after and at what engine RPM?

Intake valves will be 2.18 or 2.20 depending on "casting" availability. Goal is 1000rwhp on E70, 7000rpm shift or less and blower rpm 22K or less.... ideally . It is a Manual car

 

[jcs003]

Everyone is going 388 lately. Guess why?????

 

[07GTS]

Everyone is going 388 lately. Guess why?????

keep those skirts all snug inside the bore at BDC ?

 

[randeez]

Dart will send them out finish honed with 4.125 bore. The couple hundred bux in machine work to change the bore would just be added cost for 10 more cubes, and as above you're buying a less common piston.

 

[Rubber Duck]

keep those skirts all snug inside the bore at BDC ?

And one will need a larger camshaft or cylinder heads ....Or maybe both.

 

[Rubber Duck]

Intake valves will be 2.18 or 2.20 depending on "casting" availability. Goal is 1000rwhp on E70, 7000rpm shift or less and blower rpm 22K or less.... ideally . It is a Manual car

You have a nice build here.
But I don’t think you’re going to ‘Safely’make 1000 rear wheel horsepower using E70.

A 427 CID engine making 1000 hp means the engine is making 2.34 hp / cid.
Heads will need to flow about 375 CFM @ 28” of water.

Let’s say the engine in NA form makes 376 hp.
1000 hp minus 376 hp equals 624 hp.

I don’t believe you’re going to make an additional 624 hp with 15 psi of boost.
That would amount to about 41.6 hp / psi.

 

[twenty_below0]

Dart will send them out finish honed with 4.125 bore. The couple hundred bux in machine work to change the bore would just be added cost for 10 more cubes, and as above you're buying a less common piston.

Builder said I can order in 4.125 or 4.155, hes leaning toward 4.155 but I wanted the advice from Duck and others on here who are as experienced with this platform as they are intelligent and remove a lot of the assumption and bro science.

You have a nice build here.
But I don’t think you’re going to ‘Safely’make 1000 rear wheel horsepower using E70.

A 427 CID engine making 1000 hp means the engine is making 2.34 hp / cid.
Heads will need to flow about 375 CFM @ 28” of water.

Let’s say the engine in NA form makes 376 hp.
1000 hp minus 376 hp equals 624 hp.

I don’t believe you’re going to make an additional 624 hp with 15 psi of boost.
That would amount to about 41.6 hp / psi.

Ive read where others are making 18-20psi on their 427 with Kong 2650 and hitting the elusive 1000rwhp on Mast heads or others that flow around 400cfm at .650. A NA built 10;1.1 427 without boost will make more then 376hp the stock 376 make more then that without boost....am I missing something on what your meaning?

 

[randeez]

this isnt assumption or bro science...dart will finish hone to 4.00 or 4.125 directly from them. thats why the the 388/427 is popular and cheaper to build.

oh yea, and i also have an 1800hp 427ci build from TMS

 

[twenty_below0]

You have a nice build here.
But I don’t think you’re going to ‘Safely’make 1000 rear wheel horsepower using E70.

A 427 CID engine making 1000 hp means the engine is making 2.34 hp / cid.
Heads will need to flow about 375 CFM @ 28” of water.

Let’s say the engine in NA form makes 376 hp.
1000 hp minus 376 hp equals 624 hp.

I don’t believe you’re going to make an additional 624 hp with 15 psi of boost.
That would amount to about 41.6 hp / psi.

I have access to pump E85 but it's never more then E70 that why I referenced it, would a larger bore help or hender in this, (going to 4.155) with good flowing heads and the 2650 spun at 22K rpms

this isnt assumption or bro science...dart will finish hone to 4.00 or 4.125 directly from them. thats why the the 388/427 is popular and cheaper to build.

oh yea, and i also have an 1800hp 427ci build from TMS


View attachment 156122

Nice, thats basically what itll be with the 2650 and a custom spec'd cam, I didnt mean you as a reference with Bro science I was referring to the internet in general where 1000RWHP is being made on stock cubes and 1.9 blower, sorry bout that didnt mean to sound like an ass. I checked with builder he said yes Dart will finish the block in 4.155, so I'm going by his experience

 

[Lt1z]

4.125 bore engine 19-20 psi with good heads and a 2650 will crack 1000whp through an A6 on our dyno. Ive seen similar combos over 1100 on hub dynos but regardless its a 4 digit capable combo when done right.

 

[Rubber Duck]

4.125 bore engine 19-20 psi with good heads and a 2650 will crack 1000whp through an A6 on our dyno. Ive seen similar combos over 1100 on hub dynos but regardless its a 4 digit capable combo when done right.

Matt, you never ever specify the fuel requirement!
30 hp increase per psi on gasoline is very good for a street car!

Telling people something can be done without explaining everything
only leads to catastrophic engine failures.

We can discuss this together more if you’d like to move into the BMEP pressures versus octane requirements if you would like.

Just let me know!

RD

 

[Rubber Duck]

Ive read where others are making 18-20psi on their 427 with Kong 2650 and hitting the elusive 1000rwhp on Mast heads or others that flow around 400cfm at .650. A NA built 10;1.1 427 without boost will make more then 376hp the stock 376 make more then that without boost....am I missing something on what your meaning?

I simply use the 376 hp referencing a 376 cid engine as a reference of one horsepower per cubic inch. Anyone can take that formula based on their specific build information and solve for their build.

 

[Lt1z]

Matt, you never ever specify the fuel requirement!
30 hp increase per psi on gasoline is very good for a street car!

Telling people something can be done without explaining everything
only leads to catastrophic engine failures.

We can discuss this together more if you’d like to move into the BMEP pressures versus octane requirements if you would like.

Just let me know!

RD

Sorry, in this business there is literally no one doing this with pump or pump and meth only. Its always ethanol or ethanol and meth at those levels. Race gas is usually not the call as most are not dedicated race cars.

I wont run pump gas past 700whp and pump and meth past 800whp for safety.

You also know Im not going to write a 500 word post either. Never have, never will.

No one should be attempting anything on their own based on forum posts or what they read on Facebook only. /2cents

 

[twenty_below0]

Matt, you never ever specify the fuel requirement!
30 hp increase per psi on gasoline is very good for a street car!

Telling people something can be done without explaining everything
only leads to catastrophic engine failures.

We can discuss this together more if you’d like to move into the BMEP pressures versus octane requirements if you would like.

Just let me know!

RD

I dont think he was trying to miss lead me as I had stated previously the fuel system I had. Dual Fore system with I believe two 525 pumps, (they were the biggest pumps they offered for E85). Has stainless hard lines from back to front 10 supply, 8 return should be sufficient for my goals with e85 and 1000rwhp