Worth upgrading 862 heads?
05-24-2016, 10:46 PM
#1
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Worth upgrading 862 heads? I've got a 4.8 in my truck. I want more.
Since 6.0's are $$, I'm thinking about building a 5.3 on the stand to swap in to the truck later on.
Is it worth it to put 2.xx intake valves in a 862 head, or will they still leave a ton of power on the table?
Planning on a 210/218 @ 114 LSA cam, LS6 valve springs and possibly bore to 5.7 with flat-top pistons. Will an 862 head with a 2.xx (can't remember max size) intake valve & basic port cleanup choke a 5.7?
If I'm someday stricken by wealth, I could build a 383 - but at that point, I'm sure I'd just want new heads.
Since 6.0's are $$, I'm thinking about building a 5.3 on the stand to swap in to the truck later on.
Is it worth it to put 2.xx intake valves in a 862 head, or will they still leave a ton of power on the table?
Planning on a 210/218 @ 114 LSA cam, LS6 valve springs and possibly bore to 5.7 with flat-top pistons. Will an 862 head with a 2.xx (can't remember max size) intake valve & basic port cleanup choke a 5.7?
If I'm someday stricken by wealth, I could build a 383 - but at that point, I'm sure I'd just want new heads.
05-25-2016, 07:12 AM
#2
TECH Junkie
Putting a 2" valve will essientially give you a set of milled 241's. The 862's have the same port size and runner volume, they were just choked by the intake valve.
Open it up to the same size as the 241's and you should see an improvement across the board.
Also, the 862's have a much smaller combustion chamber volume at only 61.15 cc, around 6 cc smaller than the 241.
On another note, With that cam, the durations sound fine, but i'd switch to a tighter lsa. This will typically yeild more low end torque. LSA isnt the entire equation to the valve events, but in this case, It should help give more torque down low, great for a truck.
Open it up to the same size as the 241's and you should see an improvement across the board.
Also, the 862's have a much smaller combustion chamber volume at only 61.15 cc, around 6 cc smaller than the 241.
On another note, With that cam, the durations sound fine, but i'd switch to a tighter lsa. This will typically yeild more low end torque. LSA isnt the entire equation to the valve events, but in this case, It should help give more torque down low, great for a truck.
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Brian Girdler (01-04-2020)
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Brian Girdler (01-04-2020)
05-25-2016, 08:59 AM
#4
Define Worth? It depends on your goal and your budget.
If you're building an Iron LS1, just start with a set of 241's as they can be had cheap. If it's in the budget get some 243/799 heads.
If you're building a small bore 4.8/5.3 stay with the 862's and get some larger valves to get the most out of it.
If you put flat top 4.8 piston's in the 5.3L It will bump your compression and you can use a 241 or 243/799 head with the larger Combustion chamber.
I say this because you need to factor in the cost of the valve to upgrade the 862 heads and the 241's can be had cheap if you shop around. I have paid as little as $100 for a complete set of 241's because no one wants them. Everyone wants 243/799 castings.
The small bore applications will require milling with the larger cc heads to lower the combustion chamber CC to bring the compression up like with the 862's.
If you're building an Iron LS1, just start with a set of 241's as they can be had cheap. If it's in the budget get some 243/799 heads.
If you're building a small bore 4.8/5.3 stay with the 862's and get some larger valves to get the most out of it.
If you put flat top 4.8 piston's in the 5.3L It will bump your compression and you can use a 241 or 243/799 head with the larger Combustion chamber.
I say this because you need to factor in the cost of the valve to upgrade the 862 heads and the 241's can be had cheap if you shop around. I have paid as little as $100 for a complete set of 241's because no one wants them. Everyone wants 243/799 castings.
The small bore applications will require milling with the larger cc heads to lower the combustion chamber CC to bring the compression up like with the 862's.
Last edited by 1FastBrick; 05-25-2016 at 09:05 AM.
05-25-2016, 09:43 AM
#5
TECH Junkie
Just as an example, I called around to machine shops around me (northwest Iowa) and can get a full valve job on all 16 and larger valves cut into stock seats for about $150 Labor.
i also picked up a set of flat tops for my 5.3 for 150 bucks (gen 4 rods included)
Depending on what thickness head gasket I run, I can get anywhere from 10.5 or 10.7:1 with the 862's.
This, along with a healthy cam, should run pretty well for a little 5.3
i also picked up a set of flat tops for my 5.3 for 150 bucks (gen 4 rods included)
Depending on what thickness head gasket I run, I can get anywhere from 10.5 or 10.7:1 with the 862's.
This, along with a healthy cam, should run pretty well for a little 5.3
04-30-2018, 07:55 PM
#6
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Putting bigger valves dont do anything for you !!!! Why do all these motor builder's think going bigger on the valves make anything better ???if yr 2inc valves dont open as good as the smaller valve not much flow there you have to do everything to the head open all the head up for the 2 or 202 208 to work rite if you can port any head rite you'll make great numbers
05-01-2018, 08:05 AM
#7
Why do all these motor builder's think going bigger on the valves make anything better ???if yr 2inc valves dont open as good as the smaller valve not much flow there you have to do everything to the head open all the head up for the 2 or 202 208 to work rite if you can port any head rite you'll make great numbers
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01-04-2020, 06:04 PM
#8
862 I am putting 469rwhp on NA.. 770 rwhp with the 300 shot.
I drive it to Ga and runs great. (300 mile round trip) just bought it, and didn't realize how fast of a car I was getting..
01-07-2020, 11:26 PM
#12
01-08-2020, 08:10 PM
#13
TECH Apprentice
I still have my 241 heads that I'm going to port next to see what I can do while I read stuff from David Vizard on porting heads.
01-09-2020, 01:55 AM
#14
Thanks.
I think there ok. I don't have the curtain area for good mid lift #s. I knew that doing it this way. I just didn't know what the flow curve would look like. A different valve/vj can change that.
I think there ok. I don't have the curtain area for good mid lift #s. I knew that doing it this way. I just didn't know what the flow curve would look like. A different valve/vj can change that.
01-09-2020, 12:03 PM
#15
TECH Apprentice
Yeah mid lift numbers seem to carry a lot of weight in power production. The 862s didn't get the intake valve mod, but the 241 heads will get the intake valve mod I picked up from Vizard.
01-09-2020, 06:09 PM
#16
The 1st thing the 862 needs
One a bigger valve . To fix the 92ish% OEM seat width. A bigger valve with allow 89-90 % seat width. And that allows wider angles on the vj, You need this to get the air around the valve .anything over 90% and the stock 1.89 valve needs 50 main angle to turn the air. Those are basic rules
it is very simple to get them to flow a little better than stock 243s ,if that's what you want. But on this particular head.it starts at the valve and vj. Example no valve they flow 243cfm stock. With a valve 220-222. That's pretty basic stuff.
One a bigger valve . To fix the 92ish% OEM seat width. A bigger valve with allow 89-90 % seat width. And that allows wider angles on the vj, You need this to get the air around the valve .anything over 90% and the stock 1.89 valve needs 50 main angle to turn the air. Those are basic rules
it is very simple to get them to flow a little better than stock 243s ,if that's what you want. But on this particular head.it starts at the valve and vj. Example no valve they flow 243cfm stock. With a valve 220-222. That's pretty basic stuff.
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omc8 (02-27-2021)
01-10-2020, 11:37 AM
#17
The more I look at these 2.02 862 numbers.
the more I like them. Less low lift flow at 200 a good thing!
my 400 #s are comparable to alot of 225cc heads. And they just flow up high.
I tried a 2.04 ferrea valve. Needs more work on bench yet. Probably not worth the cost and hassle
50.00 set of heads and 50.00 set of valves.
what more could u ask for.
the more I like them. Less low lift flow at 200 a good thing!
my 400 #s are comparable to alot of 225cc heads. And they just flow up high.
I tried a 2.04 ferrea valve. Needs more work on bench yet. Probably not worth the cost and hassle
50.00 set of heads and 50.00 set of valves.
what more could u ask for.
02-20-2021, 10:31 PM
#18
The more I look at these 2.02 862 numbers.
the more I like them. Less low lift flow at 200 a good thing!
my 400 #s are comparable to alot of 225cc heads. And they just flow up high.
I tried a 2.04 ferrea valve. Needs more work on bench yet. Probably not worth the cost and hassle
50.00 set of heads and 50.00 set of valves.
what more could u ask for.
the more I like them. Less low lift flow at 200 a good thing!
my 400 #s are comparable to alot of 225cc heads. And they just flow up high.
I tried a 2.04 ferrea valve. Needs more work on bench yet. Probably not worth the cost and hassle
50.00 set of heads and 50.00 set of valves.
what more could u ask for.
02-27-2021, 06:49 PM
#19
The 1st thing the 862 needs
One a bigger valve . To fix the 92ish% OEM seat width. A bigger valve with allow 89-90 % seat width. And that allows wider angles on the vj, You need this to get the air around the valve .anything over 90% and the stock 1.89 valve needs 50 main angle to turn the air. Those are basic rules
it is very simple to get them to flow a little better than stock 243s ,if that's what you want. But on this particular head.it starts at the valve and vj. Example no valve they flow 243cfm stock. With a valve 220-222. That's pretty basic stuff.
One a bigger valve . To fix the 92ish% OEM seat width. A bigger valve with allow 89-90 % seat width. And that allows wider angles on the vj, You need this to get the air around the valve .anything over 90% and the stock 1.89 valve needs 50 main angle to turn the air. Those are basic rules
it is very simple to get them to flow a little better than stock 243s ,if that's what you want. But on this particular head.it starts at the valve and vj. Example no valve they flow 243cfm stock. With a valve 220-222. That's pretty basic stuff.