sivl92

My 2004 Honda Civic Ex has a 1.7 SOHC Vtec engine. Recently while having my mechanic change my timing belt, he noticed the block has been swapped by previous owner to a D17A1 block, instead of the VTEC D17A2. It uses a steel pan instead of an aluminum one. My question is because of the different block, will it affect the performance of the car in anyway? i.e. gas mileage, power

This is my first car so I do not any idea on how the car should feel like in its original engine/block.

Poopies

iTrader: (4)

If it's an A1 block, you don't get VTEC :-(. Less power, more gas mileage. I think the A1 is rated at 115hp while the A2 is 127hp. Actual results may vary.

GolNat

iTrader: (7)

I think the blocks are the same, its the head that gets changed.

So is it an A1 or A2 head? Does it have a VTEC solenoid?

kinakoes2

Easy way to tell the A1 and A2 apart, is the exhaust manifold: A1 has the cat right next to the head so the O2 sensor is there as well. The A2 has tubular headers stock behind the aluminum heat shield, so its LAF sensor is lower down, closer to the ground.

sivl92

Mine is an A2 engine. It says VTEC SOHC on top and there's a VTEC solenoid. I recently changed the gasket and filter of the solenoid because the previous owner somehow manage to get silicone stuck in the filter. It's just the block has been swapped before I believe. The oil pan it used is also steel too instead of aluminum like the A2 that my engine should have.

ezone

Sounds like someone replaced just the short block (with whatever was available cheapest maybe?) but kept the VTEC head.

No big deal IMO, other than it's not quite the same as original and the numbers don't match.

kinakoes2

Agree -- actually, that's I guess the hot swap for an A1 (arguably the one that gives you the most gain bhp-wise... as if there were any 'hot' bolt-ons for the D17s :P ). You do trade a bit of fuel economy for the extra 12 bhp. I get 35 mpg now though, and I know other A2 owners can attest to even more... but the A1 gets high mpg numbers even more easily, if scooting around quickly isn't as high on the bucket list.

sdaidoji

iTrader: (1)

the A2 have slightly higher compression and some oil squirts to the cylinders. aside from that, the blocks are the same. you will still have the shorter geared trans and the exhaust from the EX if they did swap only the block.

sdaidoji

iTrader: (1)

specs:
D17A1
Found in:
2001-2005 Honda Civic DX/LX/VP
Displacement : 1,668 cc (101.8 cu in)
Bore and Stroke : 75 x 94.4 mm (3.0 %u00D7 3.72 in)
Compression : 9.5:1
Power : 115 hp (85.8 kW, 117 ps) @ 6100 rpm
Torque : 110 ft/lbf (15.2 kg/m, 149 Nm) @ 4500 rpm
RPM redline: 6750 rpm
Rev-limiter : 7200 rpm
Valvetrain : SOHC (4 valves per cylinder)
Fuel Control : OBD-2 MPFI

D17a2 VTEC
Found in:
2001-2005 Honda Civic EX (US only)
2001-2005 Honda Civic LX (Europe)
2001-2005 Honda Civic Si (Canada only)
2001-2005 Acura 1.7 EL (Canada only)
2000-2007 Honda Stream 1.7 (Japan)
Displacement : 1,668 cc (101.8 cu in)
Bore and Stroke : 74.98 x 94.4 mm (2.952 %u00D7 3.72 in)
Rod Length : 137 mm
Rod/Stroke : 1.48
Compression : 9.9:1
Power : 127 hp (94.7 kW, 132 ps) @ 6300 rpm
Torque : 114 /lbf (114 /lbf USDM[3]) (15.8 kg/m, 155 Nm) @ 4800 rpm
RPM redline: 6800 rpm
Rev-limiter : 7200 rpm
Valvetrain : SOHC VTEC (4 valves per cylinder)
VTEC Switchover : 4500 rpm
Fuel Control : OBD-2 MPFI

ah, sorry, maybe piston heads difference for the compression? unsure of details

you should get somewhere close to the EX numbers, though, with the A2 head/exhaust

ezone

Just looked....EX has different part #s for its pistons than LX/DX.

sivl92

Here is some pictures of headers, VTEC solenoid, and the block

ezone

I see a bolt missing from the breather mount, and the grommet for the hose is out of place.


Otherwise, I still say it must be that someone replaced the short block with whatever was handy/cheap.

kinakoes2

Hmm... well if pistons are different... I'm thinking they must be optimized to take advantage of the oil spray (could be slightly taller yet lighter to allow faster revving, but maintain durability through the undercrown oil jets). An A1 short block would have the A1 pistons though, so (if the above is actually the case), the A2 head on an A1 bottom end would only penalize you slightly through a bit more reciprocating mass (slower revving). sdaidoji may know what the actual physical difference is between the A1 and A2 pistons, though.

ezone

I'm pretty sure it's the compression ratio difference.



Anyone care to cc the combustion chambers of each head?

sdaidoji

iTrader: (1)

Kinakoes, I believe they just changed top of pistons to increase compression.
However, my oldee lx is long gone so can't take head off t o compare, so the best chances are that ezone will have both at the shop to take measurements or pics

sdaidoji

iTrader: (1)

Btw, kinakoes, we never directly interacted, but pretty good posts, man welcome

kinakoes2

Thanks sdaidoji... it's really cool to be part of a community as helpful and non-hazing as CF (man I tried to ask some questions on honda-tech a few months ago and was ignored for weeks :P ).

I've learned megatons about my car in a very short time (props and shouts also to ezone, an old salty tech like myself who's been quite patient with my moto-only understandings but has probably taught me the most about the guts of a Civic).

Happy to help, and loving it here.

sdaidoji

iTrader: (1)

Ezone is in a level all by himself
Do you see miatas over there in Hawaii? If so, send regards to gtxhawaii not sure which island he is, though, pretty good in miata forums too

kinakoes2

^ Tbh... I bought the Civic to replace my last car, which was wrecked by a drunk while parked on the curb in Feb. Set me back a few grand... but the ultimate move is, to get a Mazda , a 2015 2.5L 3S hatch. Pretty tired of cars that can't get out of their own way... esp now since with my current gig (Rolfing, a form of deep-tissue bodywork) I had to get rid of my bikes to both protect and develop my hands for the sensitive work.

Now you can kinda see why I put up with a 1.5L (but paid-off) '92 Paseo for so long (16 yrs) -- I had my YZF1000R and later the VFR800FI and my SV racebike to feed my speed (and eat my greens in return ).

I think gtx was on O'ahu, esp if he had a Miata... he'd be miserable if he was here. On Maui, all a Miata is to the people that live here are two extremes: shiny and new/sun-baked and shredded-soft-top, grocery-got/brunched to a carbon-caked death by cougars... or covered in primer and banging on the bump stops with blown-out shocks from being off-roaded by surfer/burner/hippie types, no middle ground. It's kinda the same with S2000s here... either they're bro-modded to death, stanced with all the usual ricer poo and hinge stickers, or it's some trophy wife's car that never sees more than the speed limit and will never see the dash LCD touch redline -- sad.

Suffice to say HI has no real motorsports heritage or culture to speak of (one thing I loooooooved about Seattle, was everybody, lahdi-dahdi seemed to race something for a hobby)... but on Maui if its not mudding or drag racing, there's zero folk here who know how to properly autocross or even touge a Miata the way it deserves to be.


Back on topic... if the pistons have only a bit more material to increase compression slightly, then an A2 head on an A1 block will only slightly affect durability, if at all. Honda probably only spec'd the oil jets to insure life far into 150K and beyond, so if the pistons get slightly hotter than they would on genuine A2 motors, that just means the knock sensor will kick in sooner and you may need to run higher octane fuel than an all-A2 motor to maintain the same power when hot.

You may make that power back though, because if the A2 motor used oil jets... then the pump specs may be slightly different, meaning less viscous drag if the A2 pump moves more oil at higher pressure. However if you're thinking of turbocharging your D17... I'd definitely make sure you have those oil jets cooling the pistons.

sdaidoji

iTrader: (1)

LOL!
you know suspension of the miatas well, then!