3.0: engine block from an AT the same as MT?

**95ttht** · 03-08-2006, 14:49

Sorry for the newbie questions, I searched the FAQ and archives and couldn't find an answer to this.

Is the actual engine block/head/intake/cams/etc different between the automatic and manual versions of the 3.0L C30A engine from the early production cars? All I could find is the compression seems to be the same (10.2:1).

Other than the redline limit of the automatic transmission and the ECU programming, are the any other differences I should know about?

Ie- if I replace a bad engine in a MT car with a good (and cheaper to source) AT car motor, are there any drawbacks?

Thanks in advance!

**Larry Bastanza** · 03-08-2006, 17:00

It has different cams for sure, less power, and I think, but am not 100% sure, the ECU is different to accomodate the cam changes.

HTH,
LarryB

**sduffass** · 01-10-2010, 22:30

Bumping this up for an answer they know for sure what the differences are!

Stephen

**whrdnsx** · 01-12-2010, 01:12

I think it's just the inlet cams that are different going by what it says in the manual, Different ecu & lower RPM limit.

Is there any way to identify a MT engine from a AT engine if it's being sold on it's own? something in the engine number??

**A.S. Motorsport** · 01-12-2010, 12:09

It does have different cams
And iirc a different ecu and some other bits.

**shawn110975** · 01-12-2010, 13:17

SDUFFASS ,,, did you know you have 666 posts,,, your not the anti-christ are you??? LOL J/k

But back to the subject,, they De-Tuned the automatics I dont know how they would go about doing that but the above comments are probably right On!! but heres my thought,, they used 87octane gas, they used smaller Fuel rails with Civic Fuel Injectors, they made the air filter thicker to restrict the air, used spark plugs with lower Specs, the fuel pump is from a CRX, and the throttle body is from a CBR 900rr LOL

**Honcho** · 01-12-2010, 13:33

From Acura's own literature:

Manual:

Power (MT): 276hp (280ps) @ 7100rpm
Torque (MT): 210lb/ft (280N.m) @ 5500rpm

Power (AT): 252hp (255ps) @ 6600rpm
Torque (AT): 210lb/ft (280N.m) @ 5300rpm

Redline (MT): 8000rpm
Redline (AT): 7500rpm

As mentioned above, the AT block has less aggressive cams and a different ECU, which limits max revs to 7500. The reduction is due to the lower capacity of the AT. If you watch the transmission service video posted in another thread, they say the AT was derived from the Integra, so it kind of makes sense.

**I1O101I** · 01-13-2010, 02:38

Is this 2005 AUTOMATIC NSX a 3.0 block or is it using a 3.2?

Bryan

**sduffass** · 01-13-2010, 04:57

The engine in question would be from I think a 92 automatic Japanese Nsx. An would be torn down and semi built using parts from my mt out of my 91.

Stephen

**Honcho** · 01-13-2010, 06:13

All automatic NSX's from 1991-2005 used the 3.0L.

Originally Posted by I1O101I

Is this 2005 AUTOMATIC NSX a 3.0 block or is it using a 3.2?

Bryan

**4AU4LIFE** · 01-13-2010, 06:14

Originally Posted by I1O101I

Is this 2005 AUTOMATIC NSX a 3.0 block or is it using a 3.2?

Bryan

All auto's use the 3.0l no matter the year model. A 3.2l is only for manual trans for 97+.

**lansx-t** · 01-13-2010, 06:23

at & mt engine block are same.only block

**sduffass** · 01-13-2010, 06:28

So crank and rods = short block??

Stephen

**Honcho** · 01-13-2010, 06:37

Yes, all of the short block parts (block, caps, crank, rods, pistons) and most of the heads (castings, valves, etc.) should be the same. To make an AT 3.0 into a MT 3.0, you would need:

MT cams (4)
MT ECU

If it were me, I would go straight to the SoS high-lift NA cams and not bother with the OEM cams.

**I1O101I** · 01-13-2010, 08:49

Originally Posted by Honcho

All automatic NSX's from 1991-2005 used the 3.0L.

Originally Posted by 92NSX

All auto's use the 3.0l no matter the year model. A 3.2l is only for manual trans for 97+.

thanks for all the info, an auto na2 is just not worth it, even with the supercharger.

Bryan

**99 rs** · 01-17-2010, 02:24

There is no such thing as an auto NA2. Even in 2005 if it's auto it's NA1.

**pbassjo** · 01-17-2010, 03:39

Originally Posted by 99 rs

There is no such thing as an auto NA2. Even in 2005 if it's auto it's NA1.

Nice post.
So many don't understand that NA2 does not designate the body change that occurred with the 2002 model.
I've noticed some of the newer vendors get this wrong as well.

**4AU4LIFE** · 01-18-2010, 10:01

Originally Posted by I1O101I

thanks for all the info, an auto na2 is just not worth it, even with the supercharger.

Bryan

I don't even think they recommend putting an s/c on an automatic.

**rwdforlife** · 02-07-2010, 11:30

i am glad i came across this thread. thanks for the info.

**nsxinkl** · 02-07-2010, 21:09

Originally Posted by 92NSX

I don't even think they recommend putting an s/c on an automatic.

Before i did my auto to manual conversion recently, i had an SC on my auto. I had no issues with it.

**rwdforlife** · 02-08-2010, 12:39

Originally Posted by nsxinkl

Before i did my auto to manual conversion recently, i had an SC on my auto. I had no issues with it.

was it a direct bolt on? plug and play? What else did you had to change inorder to get the car functioniong properly?

**Quebec_Nsx** · 02-08-2010, 15:19

only the intake cam that are not the same
from the 1991 service manual--
cam lobe height standard (new):
M/T INTAKE | EXHAUST
PRIMARY | 37.086mm | 36.559mm
| (1.4601 in) | (1.4393in)

MID | 38.037mm | 37.398mm
| (1.4975in) | (1.4724in)

SECONDARY | 37.326mm | 36.741mm
(1.4695in) | (1.4465in)
_________________________________________
A/T
PRIMARY | 37.266mm | 36.559mm
| (1.4672in) | (1.4393in)

MID | 37.655mm | 37.398mm
| (1.4825in) | (1.4724in)

SECONDARY | 37.504mm | 36.741mm
| (1.4765in) | (1.4465in)

**nsxinkl** · 02-08-2010, 17:59

Originally Posted by rwdforlife

was it a direct bolt on? plug and play? What else did you had to change inorder to get the car functioniong properly?

The CTSC is a plug and play unit but i had my torque convertor beefed up by jmo for peace of mind. I would also advise you to get a piggy back ecu if you want to boost it higher than 6psi. Finally, you have to change the auto crank pully to a manual crank pully. Otherwise the boost will be higher than 6psi.

**rwdforlife** · 02-08-2010, 20:35

Originally Posted by nsxinkl

The CTSC is a plug and play unit but i had my torque convertor beefed up by jmo for peace of mind. I would also advise you to get a piggy back ecu if you want to boost it higher than 6psi. Finally, you have to change the auto crank pully to a manual crank pully. Otherwise the boost will be higher than 6psi.

besides the boost and turbo upgrade, what else would i need? i am just planning to change it from at to mt.