Thread: Blown 540 900+ on pump gas

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I have a customer that has requested 900+ hp on pump gas out of his 540.
Dart block.
4340 balanced assembly.
JE blower pistons 8.3 with 119 cc heads.
Plasma moly rings.
Custom ground Comp.cam hyd. roller cam un sure about specs. yet.
Possible .600/.625, duration at .050 255/265 112 l/s.
Yes,he has to run a hyd. cam.
Customer has a set of BB2Xtra's 365 cc port volume with 2.300/1.88 valves.
I would rather run 2.19/1.94 valves.
I.M.O.,the heads are one maybe two sizes to large as far as port volume.
8-71 from the Blower Shop.
Two flowed 850 dp that now flow 990 cfm each.
Will this engine make 900+ hp on 94 octane with 8 lbs. of boost??
This engine will be a max. effort street engine in a 2,800 lbs. car with a 3,500 stall and the gear is un-decided.
He has 3.73,3.90,4.33 gears.
I am still in the planning stages of the engine.
Your thoughts are welcome.
What would you change and why??
Fire away.

what size blower ?ok now i see the blower size heads i think are a bit to big ? what the hell do i know ? i would run a 2.250 valve 2.300?? would be better to run one more point of cr? i would run as much cr as you can with out boost

Originally Posted by pat mccarthy

what size blower ?

Blower shop 8-71.

well 800 not to bad 900?? well how much time will he spend on the dyno? headers and cams i have a hi hp cam that is a soild blower cam that makes more then that????? i will Pm the cam so you can look at it if you want it is a comp

i would think 4.500 bore and 4.250 crank????????

Originally Posted by pat mccarthy

what size blower ?ok now i see the blower size heads i think are a bit to big ? what the hell do i know ? i would run a 2.250 valve 2.300?? would be better to run one more point of cr? i would run as much cr as you can with out boost

I thought about running a little more compression am able to get through block decking and milling the heads a bit.
You know how tall the Dart blocks can be.
One of the last ones I did was 9.820 as it came from the factory.
My plan was to use the smaller intake valves to try and limit the intake flow a little bit in other words build the velocity.

Originally Posted by pat mccarthy

i would think 4.500 bore and 4.250 crank????????

Yes,that is correct.

well i think it may be hard to get that with the pump gas but velocity would be the blower running hard with a inter cooler and run a big valve to shovel it down the hole ?? i think port size would be ok on the small side but think the valve size of a 2.300 would not hurt and run more cam and cr you will have to drive the blower hard ??

Originally Posted by pat mccarthy

well i think it may be hard to get that with the pump gas but velocity would be the blower running hard with a inter cooler and run a big valve to shovel it down the hole ?? i think port size would be ok on the small side but think the valve size of a 2.300 would not hurt and run more cam and cr you will have to drive the blower hard ??

Pat, you are correct about the blower building the velocity.
I guess if 8lbs. of boost wont push it through the port nothing will.
I had a mech. roller picked out that was 265/275 at .050 with .675/.675 lift and 114 l/s.
He does not want to adust the valves that is why he wants the hyd. roller.

loose the hyd cam less you are running a rev kit on the lifters??

Originally Posted by pat mccarthy

loose the hyd cam less you are running a rev kit on the lifters??

I was a little worried about the valve being held open due to the boost.
The cam maker thinks that if I run at 150 seat and about 450 over the nose it should work fine and not hold the valve open.
I have never run over 135 seat pressure on a hyd. roller cam.
What are your thoughts on 150 seat pressure on a hyd. roller cam ???

Originally Posted by erik erikson

I was a little worried about the valve being held open due to the boost.
The cam maker thinks that if I run at 150 seat and about 450 over the nose it should work fine and not hold the valve open.
I have never run over 135 seat pressure on a hyd. roller cam.
What are your thoughts on 150 seat pressure on a hyd. roller cam ???

run 140/150 on seat and a rev kit on the lifters that the only way i would go them ss valves are not lite and the boost???i run all the hp roller cams at 140lbs i would all so add them lifters are going to hop if you can not keep them on the cam they are very heavy that is why i would add the rev kit. no way would i think of not running one on a build like this

my buddy here just built a 540. 10.25-1 compression, dart cnc pro -1 355 heads. Big comp solid roller for big inch pump gas motors. .715/.715 .260/.270 @.050 on a 112 LSA. He made 802 HP 720 TQ.

I would do do a bowl blend and gasket match and call it good......

Originally Posted by Grumpy 427

my buddy here just built a 540. 10.25-1 compression, dart cnc pro -1 355 heads. Big comp solid roller for big inch pump gas motors. .715/.715 .260/.270 @.050 on a 112 LSA. He made 802 HP 720 TQ.

10.25 is a little high on the comp. ratio. for blown applications I.M.O.