F23A1 and F23A5 differences
04-15-2014, 09:52 PM
#1
Honda-Tech Member
Thread Starter
F23A1 and F23A5 differences
This thread is mainly to get my thoughts together and to see what's possible. I'm fairly certain 99% of the time the F23A5 heads probably get scrapped, when they could actually be a cost effective alternative to swapping to a VTEC head or an earlier PT3 head for 94-97 Accord LX/DX owners.
I know it's been talked about before, but after looking and cross referencing some parts numbers on Majestic Honda's site, I think I've come to conclude a coupe of things:
1. The head casting is the same. Both part numbers are identical. This would mean that this would be the highest flowing as cast non-VTEC head in the F-series family, as the F23A1's head is the same casting and outflows the PT3(F22A) heads on the exhaust side. Being that it is the same casting, more than likely to convert this head to VTEC would just require some machining to add the LMA's for VTEC and a swap of the cam/rockers to the VTEC components. That means converting to VTEC would be VERY inexpensive if one were to come across a 'junk' head with good valvetrain.
2. The intake rockers are different(obviously), but is it possible they could be swapped onto a non-VTEC assembly to gain the advantage of roller rockers? The non-VTEC heads seem to have some sort of 'spacer' between the intake rockers to account for the loss of a 3rd lobe/rocker.
3. The exhaust rockers are also different(see next point)
4. The camshaft is unique to the F23A5. It does not cross reference to any other cams(PAB code), and may not have any aftermarket support at this time. It'd be interesting to get some measurements on this cam to see how it stacks up to the other factory non-VTEC cams. My guess is that it's smaller than both the standard non-VTEC cam and the F22A6/F22B6 cam. Making an aftermarket grind may be as easy as copying the larger lobes of an off the shelf VTEC cam grind and saving time/money by not doing the smaller of the intake lobes. The non-VTEC cam may very well be a VTEC cam core with the smaller lobes simply machined off, and a slightly less aggressive grind on the intake/exhaust. Seeing as how Bisi's specs for his cams seem to be hotter on the VTEC cams in comparison to the non-VTEC cams(although $100 more expensive), this could be the way to get the most aggressive non-VTEC regrind cam, which would mean not having to purchase an expensive billet core. That wouldn't account for the power loss, though, so it may be that the non-VTEC's lobes mimic that of the smaller VTEC lobe. That also doesn't take into account #4 listed above, but it's odd to see #6 if the rockers are indeed different, and the exhaust lobe's measurements are the same. Could we be looking at just a difference in exhaust rocker geometry?
5. The valves are the same, and may also have the largest valves of all the non-VTEC heads if the F23 valves are actually larger than the PT3 valves.
6. The exhaust springs are identical, but the intake springs are unique to the non-VTEC head. Once again, I don't think they're as strong as the F23 VTEC intake springs.
7. Valvecover is different in script, but they may be interchangeable. The spark plug holes/tubes for the non-VTEC PAA/F23A5 are on the exhaust side, just like the VTEC heads.
Those are the biggest things that I noticed right off the bat. Otherwise, they're 99% identical.
It'd be interesting to hear some of the opinions of the more experienced F-series guys in here. We may have been overlooking the F23A5 head as a nice option for those who don't want to go through with doing VTEC wiring, but would still like the high flow/velocity of the PAA head. I'd really like to get my hands on one of these and give it some measuring/testing.
I know it's been talked about before, but after looking and cross referencing some parts numbers on Majestic Honda's site, I think I've come to conclude a coupe of things:
1. The head casting is the same. Both part numbers are identical. This would mean that this would be the highest flowing as cast non-VTEC head in the F-series family, as the F23A1's head is the same casting and outflows the PT3(F22A) heads on the exhaust side. Being that it is the same casting, more than likely to convert this head to VTEC would just require some machining to add the LMA's for VTEC and a swap of the cam/rockers to the VTEC components. That means converting to VTEC would be VERY inexpensive if one were to come across a 'junk' head with good valvetrain.
2. The intake rockers are different(obviously), but is it possible they could be swapped onto a non-VTEC assembly to gain the advantage of roller rockers? The non-VTEC heads seem to have some sort of 'spacer' between the intake rockers to account for the loss of a 3rd lobe/rocker.
3. The exhaust rockers are also different(see next point)
4. The camshaft is unique to the F23A5. It does not cross reference to any other cams(PAB code), and may not have any aftermarket support at this time. It'd be interesting to get some measurements on this cam to see how it stacks up to the other factory non-VTEC cams. My guess is that it's smaller than both the standard non-VTEC cam and the F22A6/F22B6 cam. Making an aftermarket grind may be as easy as copying the larger lobes of an off the shelf VTEC cam grind and saving time/money by not doing the smaller of the intake lobes. The non-VTEC cam may very well be a VTEC cam core with the smaller lobes simply machined off, and a slightly less aggressive grind on the intake/exhaust. Seeing as how Bisi's specs for his cams seem to be hotter on the VTEC cams in comparison to the non-VTEC cams(although $100 more expensive), this could be the way to get the most aggressive non-VTEC regrind cam, which would mean not having to purchase an expensive billet core. That wouldn't account for the power loss, though, so it may be that the non-VTEC's lobes mimic that of the smaller VTEC lobe. That also doesn't take into account #4 listed above, but it's odd to see #6 if the rockers are indeed different, and the exhaust lobe's measurements are the same. Could we be looking at just a difference in exhaust rocker geometry?
5. The valves are the same, and may also have the largest valves of all the non-VTEC heads if the F23 valves are actually larger than the PT3 valves.
6. The exhaust springs are identical, but the intake springs are unique to the non-VTEC head. Once again, I don't think they're as strong as the F23 VTEC intake springs.
7. Valvecover is different in script, but they may be interchangeable. The spark plug holes/tubes for the non-VTEC PAA/F23A5 are on the exhaust side, just like the VTEC heads.
Those are the biggest things that I noticed right off the bat. Otherwise, they're 99% identical.
It'd be interesting to hear some of the opinions of the more experienced F-series guys in here. We may have been overlooking the F23A5 head as a nice option for those who don't want to go through with doing VTEC wiring, but would still like the high flow/velocity of the PAA head. I'd really like to get my hands on one of these and give it some measuring/testing.
04-22-2014, 05:32 PM
#3
Re: F23A1 and F23A5 differences
I'm not sure how much this will help as I don't have too much info... I do have some head specs that can hopefully help out a bit in comparing. This is for a few f22 and f23 engines.
EDIT:
To carry on our discussion from the other thread when throwing the f22b1 into this...
it looks like the cam dimensions and valve lift are the same for both f22/3 vtecs if I'm looking that this right.
EDIT:
To carry on our discussion from the other thread when throwing the f22b1 into this...
it looks like the cam dimensions and valve lift are the same for both f22/3 vtecs if I'm looking that this right.
Last edited by Veggie Man; 04-22-2014 at 06:05 PM.
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