Cylinder head help!!
Thread Starter
Teching In
Joined: Jul 2015
Posts: 33
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Cylinder head help!! I'm building a new engine for my airboat. Looking to make as much HP and torque as possible by 6000 rpms. Cannot spin it higher due to prop speed limitations. Just ordered a lsx tall deck block and Wiseco 11.3 to 1 Pistons. Cubic inch will be 468. What cylinder heads for under $3500 would be best? Thanks!
Thread Starter
Teching In
Joined: Jul 2015
Posts: 33
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Air Boat = Water Thunder Hi, your propeller @ 80" will spin at 3000 RPM "ish".
I helped design the Gear Reduction unit, the ratio can be chosen.
I you have a D/D (?), then your engine max RPM target would be 3200.
Dave runs 7800@2.9 reduction
Lance
I helped design the Gear Reduction unit, the ratio can be chosen.
I you have a D/D (?), then your engine max RPM target would be 3200.
Dave runs 7800@2.9 reduction
Lance
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Teching In
Joined: Jul 2015
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My reduction is 2.52 to 1. Max prop speed is 2300 RPMS. So around 5800 rpm is max engine speed.
TECH Fanatic
Joined: Aug 2009
Posts: 1,845
Likes: 255
From: Coast of San Mateo County Between Pacifica & HMB
I made 710 FWHP @ 6600 RPM with a 3.6" Stroke
(which has the same piston speed as a 4.25" Stroke
@ 5610 RPM)
if it was me one combo I would consider is MMS LS3
Heads with factory valves to save some money,
A ported GM LS3 intake again to save some money,
Combined with a Cam Motion Hydraulic Roller
Something like 240*/248* ..640"/.620"
LSA based on Kips recommendation to maximize
Torque with a 5800-6000 RPM HP Peak.
Cylinder heads are the most crucial element in your
Goals, you want at least 360 CFM @ .600" from
The smallest port size possible (highest velocity)
Combined with the least intake duration to meet
Your HP RPM Goal. An efficient Exhaust (70% E/I ideal
Will allow for ~ +8* Split) again promoting
Torque. Excess duration will waste
Torque below peak as well as raise peak torque.
11.5:1 comp 12.5:1 if you have the octane
Will be good, 1 7/8" Long Tubes or 2" Very Long
Tubes.
My .02
Good Luck
(which has the same piston speed as a 4.25" Stroke
@ 5610 RPM)
if it was me one combo I would consider is MMS LS3
Heads with factory valves to save some money,
A ported GM LS3 intake again to save some money,
Combined with a Cam Motion Hydraulic Roller
Something like 240*/248* ..640"/.620"
LSA based on Kips recommendation to maximize
Torque with a 5800-6000 RPM HP Peak.
Cylinder heads are the most crucial element in your
Goals, you want at least 360 CFM @ .600" from
The smallest port size possible (highest velocity)
Combined with the least intake duration to meet
Your HP RPM Goal. An efficient Exhaust (70% E/I ideal
Will allow for ~ +8* Split) again promoting
Torque. Excess duration will waste
Torque below peak as well as raise peak torque.
11.5:1 comp 12.5:1 if you have the octane
Will be good, 1 7/8" Long Tubes or 2" Very Long
Tubes.
My .02
Good Luck
Thread Starter
Teching In
Joined: Jul 2015
Posts: 33
Likes: 0
I made 710 FWHP @ 6600 RPM with a 3.6" Stroke
(which has the same piston speed as a 4.25" Stroke
@ 5610 RPM)
if it was me one combo I would consider is MMS LS3
Heads with factory valves to save some money,
A ported GM LS3 intake again to save some money,
Combined with a Cam Motion Hydraulic Roller
Something like 240*/248* ..640"/.620"
LSA based on Kips recommendation to maximize
Torque with a 5800-6000 RPM HP Peak.
Cylinder heads are the most crucial element in your
Goals, you want at least 360 CFM @ .600" from
The smallest port size possible (highest velocity)
Combined with the least intake duration to meet
Your HP RPM Goal. An efficient Exhaust (70% E/I ideal
Will allow for ~ +8* Split) again promoting
Torque. Excess duration will waste
Torque below peak as well as raise peak torque.
11.5:1 comp 12.5:1 if you have the octane
Will be good, 1 7/8" Long Tubes or 2" Very Long
Tubes.
My .02
Good Luck
(which has the same piston speed as a 4.25" Stroke
@ 5610 RPM)
if it was me one combo I would consider is MMS LS3
Heads with factory valves to save some money,
A ported GM LS3 intake again to save some money,
Combined with a Cam Motion Hydraulic Roller
Something like 240*/248* ..640"/.620"
LSA based on Kips recommendation to maximize
Torque with a 5800-6000 RPM HP Peak.
Cylinder heads are the most crucial element in your
Goals, you want at least 360 CFM @ .600" from
The smallest port size possible (highest velocity)
Combined with the least intake duration to meet
Your HP RPM Goal. An efficient Exhaust (70% E/I ideal
Will allow for ~ +8* Split) again promoting
Torque. Excess duration will waste
Torque below peak as well as raise peak torque.
11.5:1 comp 12.5:1 if you have the octane
Will be good, 1 7/8" Long Tubes or 2" Very Long
Tubes.
My .02
Good Luck
Teching In
Joined: Feb 2016
Posts: 38
Likes: 0
From: Whitinsville, MA
