Dart 8.1 Gen 7 Iron Heads
01-15-2011, 01:48 PM
#31
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The GM Engineering Project Manager in charge during the HP3 development program advised the following:
1.) There were two different HP3 engines developed under the General Motors HP3 Program
2.) The first 496 HP3 Gen I engine was 520 - 525hp on 87 octane with CMI exhaust and was heavily campaigned on the race circuit.
3.) The second HP3 Gen II engine was 560hp on 87 octane with CMI exhaust but was never campaigned on the race circuit. Only two early units were ever sold. These were not the 560 unit however. One was 540 hp and the other 550hp. These units were still running the last he heard. The 560hp HP3 Gen II engine was never campaigned because development work was not completed before GM exited the HP3 engine development program. The HP3 Gen II engine program work was to provide a 496 derived engine that could compete with the Merc 525EFI engine.
Innovation Marine personnel advised the following:
1.) The third 496 engine was developed by Innovation Marine after GM exited the HP3 engine development program and was designated the HPI engine.
2.) The HPI race engine was bumped up to 9.348:1comp, bigger cam, more timing, 93 octane, new forged pistons, more rpm and lots of other work which resulted in 575hp-590hp depending on configuration. The HPI was designed specifically to be competitive with the Merc 525EFI engine.
3.) Innovation Marine was not successful in campaigning the HPI engine.
It is my understanding that the same stock GM Vortec intake manifold was used for all three configurations with the only performance modifications being port matching with the heads and extrude honing.
1.) There were two different HP3 engines developed under the General Motors HP3 Program
2.) The first 496 HP3 Gen I engine was 520 - 525hp on 87 octane with CMI exhaust and was heavily campaigned on the race circuit.
3.) The second HP3 Gen II engine was 560hp on 87 octane with CMI exhaust but was never campaigned on the race circuit. Only two early units were ever sold. These were not the 560 unit however. One was 540 hp and the other 550hp. These units were still running the last he heard. The 560hp HP3 Gen II engine was never campaigned because development work was not completed before GM exited the HP3 engine development program. The HP3 Gen II engine program work was to provide a 496 derived engine that could compete with the Merc 525EFI engine.
Innovation Marine personnel advised the following:
1.) The third 496 engine was developed by Innovation Marine after GM exited the HP3 engine development program and was designated the HPI engine.
2.) The HPI race engine was bumped up to 9.348:1comp, bigger cam, more timing, 93 octane, new forged pistons, more rpm and lots of other work which resulted in 575hp-590hp depending on configuration. The HPI was designed specifically to be competitive with the Merc 525EFI engine.
3.) Innovation Marine was not successful in campaigning the HPI engine.
It is my understanding that the same stock GM Vortec intake manifold was used for all three configurations with the only performance modifications being port matching with the heads and extrude honing.
01-15-2011, 04:23 PM
#32
Racer
The GM Engineering Project Manager in charge during the HP3 development program advised the following:
1.) There were two different HP3 engines developed under the General Motors HP3 Program
2.) The first 496 HP3 Gen I engine was 520 - 525hp on 87 octane with CMI exhaust and was heavily campaigned on the race circuit.
3.) The second HP3 Gen II engine was 560hp on 87 octane with CMI exhaust but was never campaigned on the race circuit. Only two early units were ever sold. These were not the 560 unit however. One was 540 hp and the other 550hp. These units were still running the last he heard. The 560hp HP3 Gen II engine was never campaigned because development work was not completed before GM exited the HP3 engine development program. The HP3 Gen II engine program work was to provide a 496 derived engine that could compete with the Merc 525EFI engine.
Innovation Marine personnel advised the following:
1.) The third 496 engine was developed by Innovation Marine after GM exited the HP3 engine development program and was designated the HPI engine.
2.) The HPI race engine was bumped up to 9.348:1comp, bigger cam, more timing, 93 octane, new forged pistons, more rpm and lots of other work which resulted in 575hp-590hp depending on configuration. The HPI was designed specifically to be competitive with the Merc 525EFI engine.
3.) Innovation Marine was not successful in campaigning the HPI engine.
It is my understanding that the same stock GM Vortec intake manifold was used for all three configurations with the only performance modifications being port matching with the heads and extrude honing.
1.) There were two different HP3 engines developed under the General Motors HP3 Program
2.) The first 496 HP3 Gen I engine was 520 - 525hp on 87 octane with CMI exhaust and was heavily campaigned on the race circuit.
3.) The second HP3 Gen II engine was 560hp on 87 octane with CMI exhaust but was never campaigned on the race circuit. Only two early units were ever sold. These were not the 560 unit however. One was 540 hp and the other 550hp. These units were still running the last he heard. The 560hp HP3 Gen II engine was never campaigned because development work was not completed before GM exited the HP3 engine development program. The HP3 Gen II engine program work was to provide a 496 derived engine that could compete with the Merc 525EFI engine.
Innovation Marine personnel advised the following:
1.) The third 496 engine was developed by Innovation Marine after GM exited the HP3 engine development program and was designated the HPI engine.
2.) The HPI race engine was bumped up to 9.348:1comp, bigger cam, more timing, 93 octane, new forged pistons, more rpm and lots of other work which resulted in 575hp-590hp depending on configuration. The HPI was designed specifically to be competitive with the Merc 525EFI engine.
3.) Innovation Marine was not successful in campaigning the HPI engine.
It is my understanding that the same stock GM Vortec intake manifold was used for all three configurations with the only performance modifications being port matching with the heads and extrude honing.
Yeah I will go along with that..........
01-15-2011, 06:10 PM
#33
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The GM Engineering Project Manager in charge during the HP3 development program advised the following:
1.) There were two different HP3 engines developed under the General Motors HP3 Program
2.) The first 496 HP3 Gen I engine was 520 - 525hp on 87 octane with CMI exhaust and was heavily campaigned on the race circuit.
3.) The second HP3 Gen II engine was 560hp on 87 octane with CMI exhaust but was never campaigned on the race circuit. Only two early units were ever sold. These were not the 560 unit however. One was 540 hp and the other 550hp. These units were still running the last he heard. The 560hp HP3 Gen II engine was never campaigned because development work was not completed before GM exited the HP3 engine development program. The HP3 Gen II engine program work was to provide a 496 derived engine that could compete with the Merc 525EFI engine.
Innovation Marine personnel advised the following:
1.) The third 496 engine was developed by Innovation Marine after GM exited the HP3 engine development program and was designated the HPI engine.
2.) The HPI race engine was bumped up to 9.348:1comp, bigger cam, more timing, 93 octane, new forged pistons, more rpm and lots of other work which resulted in 575hp-590hp depending on configuration. The HPI was designed specifically to be competitive with the Merc 525EFI engine.
3.) Innovation Marine was not successful in campaigning the HPI engine.
It is my understanding that the same stock GM Vortec intake manifold was used for all three configurations with the only performance modifications being port matching with the heads and extrude honing.
1.) There were two different HP3 engines developed under the General Motors HP3 Program
2.) The first 496 HP3 Gen I engine was 520 - 525hp on 87 octane with CMI exhaust and was heavily campaigned on the race circuit.
3.) The second HP3 Gen II engine was 560hp on 87 octane with CMI exhaust but was never campaigned on the race circuit. Only two early units were ever sold. These were not the 560 unit however. One was 540 hp and the other 550hp. These units were still running the last he heard. The 560hp HP3 Gen II engine was never campaigned because development work was not completed before GM exited the HP3 engine development program. The HP3 Gen II engine program work was to provide a 496 derived engine that could compete with the Merc 525EFI engine.
Innovation Marine personnel advised the following:
1.) The third 496 engine was developed by Innovation Marine after GM exited the HP3 engine development program and was designated the HPI engine.
2.) The HPI race engine was bumped up to 9.348:1comp, bigger cam, more timing, 93 octane, new forged pistons, more rpm and lots of other work which resulted in 575hp-590hp depending on configuration. The HPI was designed specifically to be competitive with the Merc 525EFI engine.
3.) Innovation Marine was not successful in campaigning the HPI engine.
It is my understanding that the same stock GM Vortec intake manifold was used for all three configurations with the only performance modifications being port matching with the heads and extrude honing.
01-16-2011, 12:06 AM
#34
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Here is the spec confirmation from CompCam which is not very neat. Note that the 4 degrees cam retard is speced into the cam grind versus the actual HP3 Gen II engine which incorporated the cam retard in the cam timing chain sproket. The cam up grade was worth ~+20hp over the Gen I cam on the 525hp HP3 Gen I engine configuration. This is the cam I am currently running.
There was huge PV clearance with this Gen II cam set up versus the HP3 Gen I Crane cam which was scary close at 0.028" requiring a very very robust valve train to protect the pistons.
Here are the specs of the cam. If everything looks good just email back
"ok".
SPEC CARD# 11535907 SPEC CARD INQUIRY BY SPEC
CARD NO
PART # 46-000-9 CB8 8.1 LITER GM ROLLER CAM
CORE C99 DUMMY OVERRIDE CORE
GRIND # CB8 3410B/3411B HR116 -4
DURATION @
.050 INTAKE 238 ROCKER ARM RATIO
VALVE ADJ INTAKE .000 DURATION @ .050 EXHAUST 244
INTAKE 1.70
VALVE ADJ EXHAUST .000 LOBE LIFT INTAKE
.3510 EXHAUST 1.70
VALVE LIFT INTAKE .596 LOBE LIFT EXHAUST
.3510
VALVE LIFT EXHAUST .596 LOBE SEPARATION 116.0
DURATION .006 INTAKE
C/L 120.0
TAPPET LIFT INTAKE 293
ADVANCE 4-
TAPPET LIFT EXHAUST 299
HYDRAULIC Y
VALVE TIMING .050 OVERHEAD
CAM N
VALVE OPEN INTAKE 1- JOURNAL DIAMETER
STD .000
VALVE OPEN EXHAUST 54 RECOMMEND VALVE SPRINGS
VALVE CLOSED INTAKE 59 DEPARTMENT P
VALVE CLOSED EXHAUST 10 SPC INSTR FOR CUSTOMER
INTAKE LOBE ID 3410B GRIND INSTR FOR CAM SHOP
EXHAUST LOBE ID 3411B
DATE SETUP 02/12/2007
CORE TYPE HR
GEAR TYPE S
SMALL BASE CIRCLE N
LOBE SPACING STD
INTAKE BANK ANGLE STD
EXHAUST BANK ANGLE STD
REVERSE ROTATION N
REAR PUMP DRIVE N
FUEL PUMP LOBE Y
MATERIAL 5160
FIRING ORDER STD
There was huge PV clearance with this Gen II cam set up versus the HP3 Gen I Crane cam which was scary close at 0.028" requiring a very very robust valve train to protect the pistons.
Here are the specs of the cam. If everything looks good just email back
"ok".
SPEC CARD# 11535907 SPEC CARD INQUIRY BY SPEC
CARD NO
PART # 46-000-9 CB8 8.1 LITER GM ROLLER CAM
CORE C99 DUMMY OVERRIDE CORE
GRIND # CB8 3410B/3411B HR116 -4
DURATION @
.050 INTAKE 238 ROCKER ARM RATIO
VALVE ADJ INTAKE .000 DURATION @ .050 EXHAUST 244
INTAKE 1.70
VALVE ADJ EXHAUST .000 LOBE LIFT INTAKE
.3510 EXHAUST 1.70
VALVE LIFT INTAKE .596 LOBE LIFT EXHAUST
.3510
VALVE LIFT EXHAUST .596 LOBE SEPARATION 116.0
DURATION .006 INTAKE
C/L 120.0
TAPPET LIFT INTAKE 293
ADVANCE 4-
TAPPET LIFT EXHAUST 299
HYDRAULIC Y
VALVE TIMING .050 OVERHEAD
CAM N
VALVE OPEN INTAKE 1- JOURNAL DIAMETER
STD .000
VALVE OPEN EXHAUST 54 RECOMMEND VALVE SPRINGS
VALVE CLOSED INTAKE 59 DEPARTMENT P
VALVE CLOSED EXHAUST 10 SPC INSTR FOR CUSTOMER
INTAKE LOBE ID 3410B GRIND INSTR FOR CAM SHOP
EXHAUST LOBE ID 3411B
DATE SETUP 02/12/2007
CORE TYPE HR
GEAR TYPE S
SMALL BASE CIRCLE N
LOBE SPACING STD
INTAKE BANK ANGLE STD
EXHAUST BANK ANGLE STD
REVERSE ROTATION N
REAR PUMP DRIVE N
FUEL PUMP LOBE Y
MATERIAL 5160
FIRING ORDER STD
Last edited by Rage; 01-16-2011 at 12:20 AM.
01-16-2011, 07:53 PM
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496 Competition
Nothing wrong with some competition in the realm of trying to get a little extra ummpff out of the 496. Everyone who is in the performace industry is in competition.
Whipple has their Procharger
Dana Marine has their CMI
etc. etc.
I think it is great that Tyler Crockett is doing some R&D in the 496. There are alot of consumers with this engine package who are looking at different alternatives.
Looking forward to seeing the results.
Whipple has their Procharger
Dana Marine has their CMI
etc. etc.
I think it is great that Tyler Crockett is doing some R&D in the 496. There are alot of consumers with this engine package who are looking at different alternatives.
Looking forward to seeing the results.
01-16-2011, 11:48 PM
#36
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What really was the winning HP3 factory stock race engine??
Rage:
The cam spec. you have listed here is a good indicator of what really went on in the GMC HP3 engine program used at Innovation for the factory race program that eventually lost the person in charge of this program at GMC his job and caused a huge flap at GM Performance.
If you check carefully you will find out that on a stock block 8.1L GM engine with stock factory pistons as the HP3 program was supposed to be based on that any intake lift in a camshaft with 114 to 119 LSA and durations of 232 to 238 @.050" that is greater than .540" will bring the stock intake valve in direct contact with the shallow valve relief on the stock piston at approximately TDC to 8-10 degrees ATDC !
The camshaft you list has a lift of .596" which would be impossible in a stock 496-8.1L engine without major piston and engine damage. This is where and how the HP3 engine program got in trouble as it was found that the pistons in the stock engine were being changed out for special modified units to use bigger cams and other work to get the 496 HP3 up to 550-560HP levels it needed to compete and win against Mercury Racings HP525efi engine which produces 550 to 560HP in factory stock Mercury trim.
When GM High Performance even started to market the new GM HP3 engine in the new 2004 catalog and even took many orders it had to cancel and apologize for when it was learned that the HP3 was not really possible with a stock 8.1L block even with CNC'd special valve spring heads and CMI headers. In this stock block configuration it would not even produce 525Hp on GM's own dynos and GM High Performance had to cancel the offering program, reprint the entire catalog and apologize to many of their large engine sales distributors. If you had talked to the real honest people in the know on this project they would tell you how big the flap was over this and how relationships and even some jobs were severed over this semi-short lived project.
I would love to have someone show me a stock block 496 that most all users and owner have and have it produce with factory cnc'd heads, a camshaft with lifts capable of clearing the stock pistons and an absolutely stock intake manifold and the stock GM multec marine injectors and headers and have it produce 525HP at 5000-5100 rpms.
If you notice in Tylers pictures the pistons are aftermarket forgings with very deep valve reliefs capable of accepting camshaft lifts most likely at or in excess of .600". With the better flowing heads like the Raylar aluminum head or this new Dart offering, a big .600"+ lift camshaft, a good ecm program and an intake capable of flowing the required cfm that 575HP can be easily made with headers. Remember that a stock block 496 with a Raylar 103 kit with its intake manifld will produce 560-570HP with headers and a similarly equipped 496 with forged pistons and a bigger Raylar 106 camshaft will produce about 610-620HP with headers and a slight ecm reprogram. I still don't believe that any stock block 496 with any stock piston clearance grind camshaft will produce over 525HP with the stock intake manifold and throttle body.
Lets send something like this to a calibrated certified independent dyno test and prove me right or wrong.
My point here is I don't like to see the hundreds of stock 496 owners out there on OSO and such be falsely led to believe that they can simply upgrade the camshaft in their stock 496, bolt on a set of iron Dart heads, use the stock intake, throttle body, injectors and a set of headers and simply receive 575HP Abra Cadabra !, just like that! My professional knowledge , experience and opinion says it ain't gonna happen! But I am also open minded and can make apologies humbly if I am shown otherwise.
Can a 496 engine be modified to produce 575HP with major mods, intake manifold included, hell yes, we do it all the time and your 600HP -496 with the Raylar intake manifold proves that scenario quite nicely.
I just want the real comparisons and results to be qualified and quantified so that potential buyers and users will know exactly what horsepower levels they can achieve with both stock block 496's and modified block 496's so they can also see the total expense they will have to spend and modifications required before they will receive these particular horsepower output levels.
Best Regards,
Ray @ Raylar
The cam spec. you have listed here is a good indicator of what really went on in the GMC HP3 engine program used at Innovation for the factory race program that eventually lost the person in charge of this program at GMC his job and caused a huge flap at GM Performance.
If you check carefully you will find out that on a stock block 8.1L GM engine with stock factory pistons as the HP3 program was supposed to be based on that any intake lift in a camshaft with 114 to 119 LSA and durations of 232 to 238 @.050" that is greater than .540" will bring the stock intake valve in direct contact with the shallow valve relief on the stock piston at approximately TDC to 8-10 degrees ATDC !
The camshaft you list has a lift of .596" which would be impossible in a stock 496-8.1L engine without major piston and engine damage. This is where and how the HP3 engine program got in trouble as it was found that the pistons in the stock engine were being changed out for special modified units to use bigger cams and other work to get the 496 HP3 up to 550-560HP levels it needed to compete and win against Mercury Racings HP525efi engine which produces 550 to 560HP in factory stock Mercury trim.
When GM High Performance even started to market the new GM HP3 engine in the new 2004 catalog and even took many orders it had to cancel and apologize for when it was learned that the HP3 was not really possible with a stock 8.1L block even with CNC'd special valve spring heads and CMI headers. In this stock block configuration it would not even produce 525Hp on GM's own dynos and GM High Performance had to cancel the offering program, reprint the entire catalog and apologize to many of their large engine sales distributors. If you had talked to the real honest people in the know on this project they would tell you how big the flap was over this and how relationships and even some jobs were severed over this semi-short lived project.
I would love to have someone show me a stock block 496 that most all users and owner have and have it produce with factory cnc'd heads, a camshaft with lifts capable of clearing the stock pistons and an absolutely stock intake manifold and the stock GM multec marine injectors and headers and have it produce 525HP at 5000-5100 rpms.
If you notice in Tylers pictures the pistons are aftermarket forgings with very deep valve reliefs capable of accepting camshaft lifts most likely at or in excess of .600". With the better flowing heads like the Raylar aluminum head or this new Dart offering, a big .600"+ lift camshaft, a good ecm program and an intake capable of flowing the required cfm that 575HP can be easily made with headers. Remember that a stock block 496 with a Raylar 103 kit with its intake manifld will produce 560-570HP with headers and a similarly equipped 496 with forged pistons and a bigger Raylar 106 camshaft will produce about 610-620HP with headers and a slight ecm reprogram. I still don't believe that any stock block 496 with any stock piston clearance grind camshaft will produce over 525HP with the stock intake manifold and throttle body.
Lets send something like this to a calibrated certified independent dyno test and prove me right or wrong.
My point here is I don't like to see the hundreds of stock 496 owners out there on OSO and such be falsely led to believe that they can simply upgrade the camshaft in their stock 496, bolt on a set of iron Dart heads, use the stock intake, throttle body, injectors and a set of headers and simply receive 575HP Abra Cadabra !, just like that! My professional knowledge , experience and opinion says it ain't gonna happen! But I am also open minded and can make apologies humbly if I am shown otherwise.
Can a 496 engine be modified to produce 575HP with major mods, intake manifold included, hell yes, we do it all the time and your 600HP -496 with the Raylar intake manifold proves that scenario quite nicely.
I just want the real comparisons and results to be qualified and quantified so that potential buyers and users will know exactly what horsepower levels they can achieve with both stock block 496's and modified block 496's so they can also see the total expense they will have to spend and modifications required before they will receive these particular horsepower output levels.
Best Regards,
Ray @ Raylar
Last edited by Raylar; 01-16-2011 at 11:55 PM.
01-17-2011, 01:01 PM
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Ray,
I started with a new 2004 Merc 496HO and built a simulated HP3 Gen I engine using new HP3 parts: heads, Crane cam, Trend push rods, Crane roller rocker arms and port matched the intake to the heads. I retained the stock lifters, oil pump, Merc PCM555 calibration (except increased rpm limit to HP3 spec 5300rpm and fuel pressure to 50 psi to get to 12.5 AFR). I used Comp Cam 929 springs instead of the HP3 CompCam Nascar springs because the higher 437# load Nascar springs would require the HP3 Crane lifters. The HP3 Gen I cam spec is attached. The min intake valve to piston clearance was very close (0.03") but it did not hit the stock 496 piston as you believe. Clay does not lie. GM engineering stated that the design clearance was 0.028". Since I did not use the HP3 Nascar springs, I wanted a bigger factor of safety for PV clearance should the valves bounce with the 929 springs so I increased the piston valve releafs to 0.070" with an Isky cutter (I do not recommend cutting these stock pistons to anyone). I ran this motor config for 80 hours
Also attached is the prop shaft dyno test of this simulated HP3 Gen I motor. At the prop with wet exhaust it produced 442.4 hp. Given the documented 11% hp loss through the Bravo X1 drive that would be 491.3 cshp. Add to that ~20hp loss do to wet exhaust that translates to 511 hp. Keep in mind that this motor still had the stock Merc exhaust manifolds (except turbulators removed and ported to balance the flow areas). If this stock exhaust were replaced with the HP3 spec'd CMI tubular headers and run dry exhaust all they would have to add would be ~10 hp to get to the 520cshp level when tested with dry exhaust dyno headers.
The HP3 Gen II cam that you commented on in the preceeding was also subsequently installed in this same engine with the same intake manifold and same stock pistons (except with that 0.040" additional valve relief cut into them as previously described). Not only did the valves not hit the pistons their min PV clearance was a whopping 0.250"+. The 4 degrees cam retard was speced by GM to provide an additional 10 hp and may have provided the additional benefit of a very safe PV clearance in the HP3 Gen II engine. When I changed to the HP3 Gen II cam I added the Dana Flow Torque Exhaust as well and additional ECU recal's. I have no dyno data on this motor config but it ran a lot stronger than the HP3 Gen I config. I ran this motor config for 40 hours.
I started with a new 2004 Merc 496HO and built a simulated HP3 Gen I engine using new HP3 parts: heads, Crane cam, Trend push rods, Crane roller rocker arms and port matched the intake to the heads. I retained the stock lifters, oil pump, Merc PCM555 calibration (except increased rpm limit to HP3 spec 5300rpm and fuel pressure to 50 psi to get to 12.5 AFR). I used Comp Cam 929 springs instead of the HP3 CompCam Nascar springs because the higher 437# load Nascar springs would require the HP3 Crane lifters. The HP3 Gen I cam spec is attached. The min intake valve to piston clearance was very close (0.03") but it did not hit the stock 496 piston as you believe. Clay does not lie. GM engineering stated that the design clearance was 0.028". Since I did not use the HP3 Nascar springs, I wanted a bigger factor of safety for PV clearance should the valves bounce with the 929 springs so I increased the piston valve releafs to 0.070" with an Isky cutter (I do not recommend cutting these stock pistons to anyone). I ran this motor config for 80 hours
Also attached is the prop shaft dyno test of this simulated HP3 Gen I motor. At the prop with wet exhaust it produced 442.4 hp. Given the documented 11% hp loss through the Bravo X1 drive that would be 491.3 cshp. Add to that ~20hp loss do to wet exhaust that translates to 511 hp. Keep in mind that this motor still had the stock Merc exhaust manifolds (except turbulators removed and ported to balance the flow areas). If this stock exhaust were replaced with the HP3 spec'd CMI tubular headers and run dry exhaust all they would have to add would be ~10 hp to get to the 520cshp level when tested with dry exhaust dyno headers.
The HP3 Gen II cam that you commented on in the preceeding was also subsequently installed in this same engine with the same intake manifold and same stock pistons (except with that 0.040" additional valve relief cut into them as previously described). Not only did the valves not hit the pistons their min PV clearance was a whopping 0.250"+. The 4 degrees cam retard was speced by GM to provide an additional 10 hp and may have provided the additional benefit of a very safe PV clearance in the HP3 Gen II engine. When I changed to the HP3 Gen II cam I added the Dana Flow Torque Exhaust as well and additional ECU recal's. I have no dyno data on this motor config but it ran a lot stronger than the HP3 Gen I config. I ran this motor config for 40 hours.
Last edited by Rage; 01-17-2011 at 01:14 PM.
01-17-2011, 03:09 PM
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Dart Gen 7, 8.1 Head Test Data Available
Tyler,
When will the dyno test data and the head CFM flow bench data on the new Dart heads be available for us to see?
When will the dyno test data and the head CFM flow bench data on the new Dart heads be available for us to see?
01-17-2011, 03:11 PM
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Rage:
Some good information and results from your build outs and prop shaft dyno results! Its also obvious that from your build and description of cutting deeper valve reliefs in the pistons that the stock block GM/Mercury engines cannot accept even the HP3-1 camshafts with their .590-.610" lifts even with the retarded install on the camshaft I think clearance would be closer than or touching and not the .030" you apparently measured do to lifter bleed off when testing with hydraulic lifters, when the engine would be running and lifter not bleeding off the clearance would be .000" and damage would result no matter what springs were used. this is exactly where the HP3 engine program got into trouble and only special mods or pistons could solve the lift and clearances and provide HP near or slightly above 525HP that GM and Innovation were supposedly producing.
The whole point here is that any 496 properly modified in the block and with good cams and heads and headers can get close to 525HP, but the intake manifold is definitely the limiter as we found in all our testing back in 2002-2004.
As I have said no stock block 496 with any head, camshaft, headers and stock intake manifold and throttle body is going to make anywhere close to 575HP in my humble opinion. Build the block with good forged-deep valve pocket pistons and rods, add a good camshaft and good heads with good springs and valve train, use a good intake like Raylar's CoolGap and run a good header exhaust, reprogram the Mercury ECM and add a bigger throttle body and a 496 owner can have over 600HP+ at 5300 rpms. Our Raylar HO600's have demonstrated that on dynos and in customers boats for many years. Choke off this type of 496 build with a stock intake manifold and throttle body and you will not get there!
Best Regards,
Ray @ Raylar
Some good information and results from your build outs and prop shaft dyno results! Its also obvious that from your build and description of cutting deeper valve reliefs in the pistons that the stock block GM/Mercury engines cannot accept even the HP3-1 camshafts with their .590-.610" lifts even with the retarded install on the camshaft I think clearance would be closer than or touching and not the .030" you apparently measured do to lifter bleed off when testing with hydraulic lifters, when the engine would be running and lifter not bleeding off the clearance would be .000" and damage would result no matter what springs were used. this is exactly where the HP3 engine program got into trouble and only special mods or pistons could solve the lift and clearances and provide HP near or slightly above 525HP that GM and Innovation were supposedly producing.
The whole point here is that any 496 properly modified in the block and with good cams and heads and headers can get close to 525HP, but the intake manifold is definitely the limiter as we found in all our testing back in 2002-2004.
As I have said no stock block 496 with any head, camshaft, headers and stock intake manifold and throttle body is going to make anywhere close to 575HP in my humble opinion. Build the block with good forged-deep valve pocket pistons and rods, add a good camshaft and good heads with good springs and valve train, use a good intake like Raylar's CoolGap and run a good header exhaust, reprogram the Mercury ECM and add a bigger throttle body and a 496 owner can have over 600HP+ at 5300 rpms. Our Raylar HO600's have demonstrated that on dynos and in customers boats for many years. Choke off this type of 496 build with a stock intake manifold and throttle body and you will not get there!
Best Regards,
Ray @ Raylar
