Reliability Upgrades for HP500EFI?
10-17-2004, 08:20 AM
#1
Registered User
Thread Starter
Join Date: Feb 2002
Location: Belleville, IL
Posts: 199
Likes: 0
Received 0 Likes
on
0 Posts
Reliability Upgrades for HP500EFI?
I am into a complete rebuild of my '99 HP500 EFI. My question concerns internal upgrades. Are there better pistons or cam shafts to put in the motor rather than Mercury/GM replacement parts?
Are there any other upgrades that you guys have found worth the cost either in HP gains or reliability improvements.
Are there any other upgrades that you guys have found worth the cost either in HP gains or reliability improvements.
10-17-2004, 09:07 AM
#2
Platinum Member
Platinum Member
Re: Reliability Upgrades for HP500EFI?
Double valvesprings of around 140# on the seat. Keeps the lifters controlled better. Stock springs will heat fatigue. Crane rockers "good enough".
Stock oiling system adequate, but a deep oil pan is always a nice addition (with a windage screen and maybe a set of crank scrapers - as they keep the oil mist down inside - plus the big oil pan can be run at a lower level and that helps too if you use a longer pickup tube and recalibrate the dipstick).
You "can" run the gapless top ring package for a little help. Some people don't like em, but I still haven't heard anything bad about the gapless TOP ring. The older style gapless SECOND ring could encourage some cylinder wear due to lack of top ring lubrication. Some like a low tension oil ring with the gapless package. This setup is about $400 versus $90 for a standard ring set, and a lot of people don't trust it.
Unless you want to change the CR, the factory JE pistons are fine. Good slugs. Stock rotating assembly is fine to 6000+ rpm. You might want to spend a few $$ and have the whole assembly rebalanced (with flywheel and balancer). Clevite H is hard to beat for a proven bearing set.
Heads (AFR) are a shocking improvement in performance, and there are many cams to choose from with more aggressive grinds (but a more aggressive grind will be harder on the valvetrain and the AFR's seem to do really well with "polite" lobe profiles). If you stick with GM heads, pocket porting and a 3 angle valve job provides cost effective improvement.
A current thread exhibits dyno numbers on a mild 454 with AFR 305's and a Crane 761 with a 600hp potential.
Depends on what you want and expect.
Stock oiling system adequate, but a deep oil pan is always a nice addition (with a windage screen and maybe a set of crank scrapers - as they keep the oil mist down inside - plus the big oil pan can be run at a lower level and that helps too if you use a longer pickup tube and recalibrate the dipstick).
You "can" run the gapless top ring package for a little help. Some people don't like em, but I still haven't heard anything bad about the gapless TOP ring. The older style gapless SECOND ring could encourage some cylinder wear due to lack of top ring lubrication. Some like a low tension oil ring with the gapless package. This setup is about $400 versus $90 for a standard ring set, and a lot of people don't trust it.
Unless you want to change the CR, the factory JE pistons are fine. Good slugs. Stock rotating assembly is fine to 6000+ rpm. You might want to spend a few $$ and have the whole assembly rebalanced (with flywheel and balancer). Clevite H is hard to beat for a proven bearing set.
Heads (AFR) are a shocking improvement in performance, and there are many cams to choose from with more aggressive grinds (but a more aggressive grind will be harder on the valvetrain and the AFR's seem to do really well with "polite" lobe profiles). If you stick with GM heads, pocket porting and a 3 angle valve job provides cost effective improvement.
A current thread exhibits dyno numbers on a mild 454 with AFR 305's and a Crane 761 with a 600hp potential.
Depends on what you want and expect.
Last edited by mcollinstn; 10-17-2004 at 09:19 AM.
10-18-2004, 07:13 AM
#3
Registered User
Thread Starter
Join Date: Feb 2002
Location: Belleville, IL
Posts: 199
Likes: 0
Received 0 Likes
on
0 Posts
Re: Reliability Upgrades for HP500EFI?
Thanks mcollinstn, if you use the AFR heads do you need to reprogram the ECM. If I kept everything stock (pistons, CR, came, etc) except the heads, which heads would you recommend?
10-18-2004, 08:49 AM
#4
Platinum Member
Platinum Member
Re: Reliability Upgrades for HP500EFI?
My guess is that you'll need a reprogram and maybe bigger throttle plates. I haven't had the opportunity to mess with the 500EFI intake and throttle body but I would expect it to be running out of air at much more than stock hp. There are guys here that know a ton more about that unit's capabilities than I do.
If the unit (intake runners and throttle body) are capable of 600hp flow volume, then you will have to be able to supply enough fuel. There are curves for each injector size that determines the recommended max flow rates at a particular pressure and injector cycle pulse. You usually shouldn't run more than 20% more fuel pressure than they recommend, and don't run the injectors over 90% of full static on. I play with FI on bikes and cars a bit, but just haven't played with the Merc units yet.
There are good heads out there. The Edelbrock aluminum is a nice head. The AFR is standing on the top of the pile though. 305 is a great size for a NA motor of your size.
If the unit (intake runners and throttle body) are capable of 600hp flow volume, then you will have to be able to supply enough fuel. There are curves for each injector size that determines the recommended max flow rates at a particular pressure and injector cycle pulse. You usually shouldn't run more than 20% more fuel pressure than they recommend, and don't run the injectors over 90% of full static on. I play with FI on bikes and cars a bit, but just haven't played with the Merc units yet.
There are good heads out there. The Edelbrock aluminum is a nice head. The AFR is standing on the top of the pile though. 305 is a great size for a NA motor of your size.
