Difference in engine or computer

[GBL1]

I am sure that this topic has been discussed before (or maybe it's just common knowledge that eludes me), but I seem to have not been able to find it from a search.

We all know that the manual NA1 NSX w/ 3.0 liter was 270hp with 255hp for the automatic tranny, and that the NA2 NSX w/ 3.2 liter was 290hp with 270hp for the automatic trans.

My question: is the horsepower difference in the engine, something tuned back in the computer, or simply a HP loss due to the power being routed through an automatic transmission?

In other words, if one has a manual trans car, and puts an engine from an automatic car into (or vice-versa), what HP will he have?

Curious...

 

[shawn110975]

all autos NSX's from 1991-2005 are a 3.0L engine with 253 HP, not 270.

none were 3.2L Auto's

 

[Huck]

Factory Horse Power is typically measured and stated by the manufacturers at the rear of the engine---not at the rear wheel. Those who measure hp for performance will measure at the rear wheel on a dyno---. The transmission will make a difference in performance but not so much on rear wheel HP. There are some who preach really meaningful power is not HP but in Torque---the ability to twist the gears & axles around in circles. I like to consider both but there are lots of stuff that can change the performance and speed like gear ratio's, rear axle gears, tire sizes, HP/torque curves, etc.
It's kind of like a guy who bugged me years ago about lowering his BMW spending big bucks---I told him to just put some wide 13" tires and wheels on it. It went down, way down---hehehehe

 

[COUPE DE GRACE]

what would make the difference ??..LARGER PISTONS..or is there more to it

 

[GBL1]

O.K., I guess I didn't pay too much attention...I was unaware that the '97 & newer automatic cars kept the 3.0 engine. I could have sworn I read somewhere that they got a roughly 20hp bump just like the manual cars.

Still, what causes or makes the hp difference on the '91 to '96 cars from automatic to manual...?

 

[nsxtasy]

We all know that the manual NA1 NSX w/ 3.0 liter was 270hp with 255hp for the automatic tranny, and that the NA2 NSX w/ 3.2 liter was 290hp with 270hp for the automatic trans.

all autos NSX's from 1991-2005 are a 3.0L engine with 253 HP, not 270.

So I guess I'm the only one here who knows that all the automatic NSXs were quoted by Acura as having 252 horsepower, huh? :biggrin:

(Here are the specs from one of the sales brochures, from 1997 or later.)

 

[alum04org]

252 advertised HP in 2005 LBBP auto #2.

 

[PATCHEZ]

O.K., I guess I didn't pay too much attention...I was unaware that the '97 & newer automatic cars kept the 3.0 engine. I could have sworn I read somewhere that they got a roughly 20hp bump just like the manual cars.

Still, what causes or makes the hp difference on the '91 to '96 cars from automatic to manual...?

Different cams and tune.

 

[GBL1]

Different cams and tune.

So...if you have, say a 1992 model w/ manual...& you swap the engine for one out of a '92 that originally came with an automatic, then you are now dealing with a '92 car (w/ manual still) that is only putting out 252 hp, am I correct?

I always guessed that only getting 252 hp was a "punishment" for ordering an automatic b/c that's not what sports cars are meant to have.

"Real men use three pedals."

 

[shawn110975]

GBL1 ALL NSX autos are 3.0L your last statement was

"I was unaware that the '97 & newer automatic cars kept the 3.0 engine"

it should be

"I was unaware that ALL automatic cars kept the 3.0 engine"

as for spending 8-9K to upgrade and auto to a manual you could have just got one thats already Manual.

as for swapping a blown manual engine for a working Auto engine, just keep the Manual heads/cams,
that should work but dont quote me. since its was already a Manual the ECU will still be tuned

 

[GBL1]

GBL1 ALL NSX autos are 3.0L your last statement was

"I was unaware that the '97 & newer automatic cars kept the 3.0 engine"

it should be

"I was unaware that ALL automatic cars kept the 3.0 engine"

as for spending 8-9K to upgrade and auto to a manual you could have just got one thats already Manual.

as for swapping a blown manual engine for a working Auto engine, just keep the Manual heads/cams,
that should work but dont quote me. since its was already a Manual the ECU will still be tuned

O.K., I could have worded it differently, but I was speaking with the assumed understanding that, of course, the early cars all had the 3.0. Newer cars (manual) got 3.2 & the autos stayed with a 3.0 displacement.


So if I understand you correctly, the part of the car that is responsible for the HP reduction on an automatic is different heads/cams and the tuning of the ECU?

I don't ever plan on getting an automatic unless it was as nothing more than a fun daily runabout, nor at this time do I plan any such engine swapping or upgrading of an automatic, I was just mechanically curious about the how it was accomplished...

Now I'm curious about the "why" they did that to the automatics....

Was it a "punishment" for getting auto or was the manual hp bump a "bonus treat" for going manual?

My theory: Was it that Honda didn't think their automatic transmissions would handle the 270hp (all of their auto trannys have been plagued with problems in the past).

Anyone?

 

[tbromley]

Not a punishment but making sure not to put anymore power to the tranny than it could handle. They were worried about the tranny. One of our members took theirs to the track and burned up the tranny in 2 days. I would advise against that. His car needed the tranny fluid changed if that may have been a contributing factor.

O.K., I could have worded it differently, but I was speaking with the assumed understanding that, of course, the early cars all had the 3.0. Newer cars (manual) got 3.2 & the autos stayed with a 3.0 displacement.


So if I understand you correctly, the part of the car that is responsible for the HP reduction on an automatic is different heads/cams and the tuning of the ECU?

I don't ever plan on getting an automatic unless it was as nothing more than a fun daily runabout, nor at this time do I plan any such engine swapping or upgrading of an automatic, I was just mechanically curious about the how it was accomplished...

Now I'm curious about the "why" they did that to the automatics....

Was it a "punishment" for getting auto or was the manual hp bump a "bonus treat" for going manual?

My theory: Was it that Honda didn't think their automatic transmissions would handle the 270hp (all of their auto trannys have been plagued with problems in the past).

Anyone?

 

[Sumeronthechain]

Were they really concerned that an extra 20 hp would threaten the life and well being of the transmission?

Seems a bit odd.

 

[GBL1]

Honda automatic transmissions get called "crap-o-matic" sometimes.

I personally have had to replace two Accord auto trannys before.

 

[Hapa88]

Different cams and tune.

and lower redline. ..

 

[Honcho]

The NSX auto trans is actually a very sophisticated unit for 1990. I have a Acura tech training video, which describes its internals briefly. Contrary to most people who think it is a re-worked Integra trans, it was instead specifically developed for the NSX. It has some cool functions (especially for the time) like shift hold, which are intended for track driving. I think Honda had certain size and weight limitations (specific to the NSX concept) that prevented them from being able to build a beefy enough unit to handle the full 270hp reliably. There is Honda literature out there that suggests this was the reason for the reduction.

As for the differences from the manual, the auto uses camshafts with a less aggressive profile and the ECU limits rpm to 7500 instead of 8000. In Japan, there is a trend of people converting their auto NSXs to 6-speeds, as the auto engines tend to be less worn/abused than the manuals. But, to do the swap right, you need to change the cams and ECU to a manual.

As Tim mentioned, we recently had a member blow up his auto at a track event. While new autos were totally fine for track driving, now even at the lower power level, some of these units are 20 years old and simply cannot handle the abuse anymore. The main problem with this is that Honda has stopped producing replacement parts for the auto, so all you can replace it with is another used auto. Not good.

Personally, I see little reason to own an auto NSX, unless you have a physical impairment that prevents you from being able to operate a manual transmission. In such case, I think the auto is a great way to experience the car, since the handling characteristics are the same between the auto and manual.

O.K., I could have worded it differently, but I was speaking with the assumed understanding that, of course, the early cars all had the 3.0. Newer cars (manual) got 3.2 & the autos stayed with a 3.0 displacement.


So if I understand you correctly, the part of the car that is responsible for the HP reduction on an automatic is different heads/cams and the tuning of the ECU?

I don't ever plan on getting an automatic unless it was as nothing more than a fun daily runabout, nor at this time do I plan any such engine swapping or upgrading of an automatic, I was just mechanically curious about the how it was accomplished...

Now I'm curious about the "why" they did that to the automatics....

Was it a "punishment" for getting auto or was the manual hp bump a "bonus treat" for going manual?

My theory: Was it that Honda didn't think their automatic transmissions would handle the 270hp (all of their auto trannys have been plagued with problems in the past).

Anyone?

 

[nsxtasy]

the ECU limits rpm to 7000 instead of 8000.

I think you mean it limits it to 7500. :wink:

 

[mcano]

I'm probably the guy that has been referred as the prime member who blew his auto trans at the tack.

I own a 95 auto, which had about 110,000 miles on the clock when I participated in the HPDE at NSXPO in Las Vegas. I was in the novice group and this was my first track experience, other than spirited parade laps at Laguna Seca during the American Lemans Series Races.

On the second day of the HPDE I developed transmission problems. I lost 3rd gear, and then 1st and 4th, which forced me to stop running. These problems developed after I spun out on the track (3 spins at hairpin corners and 30-35 mph). However, I never received a response as to whether running an auto trans backwards during a spin could result in trans damage. Note: although my car has the Sports Shifter, my instructor insisted that I keep it in full auto mode so that I could concentrate on driving the line.

I had the trans rebuilt in December. The trans shop believed that the strains of tracking an auto at its limits, coupled with high mileage and probably old fluid was too much for the trans. The trans shop showed me the clutch packs and the ones that went bad had little to no friction surfacing left. The debris from the failed friction material caused other problems, basically in the valve body. I would say that I was guilty of not replacing the trans fluid before the HPDE. I changed all other fluids, but not the trans fluid. I learned after the fact that the filter on the NSX auto trans is internal and not accessible for period cleaning. So, it would appear that regular trans fluid replacement, particularly prior track events, would help prolong trans life.

Based on my experience, I would caution an auto trans owner on tracking their car, unless they can afford a trans rebuild should things go wrong. The cost to rebuild my trans was 3k and it came with a 3-year transferable warranty.

 

[Honcho]

I think you mean it limits it to 7500. :wink:

Thanks Ken, I think I was typing too fast!

 

[StmpoRaceProducts]

Different cams and tune.

this is correct

 

[mike.]

Bump from the dead!

So just to clarify - I'm thinking of swapping an auto engine into a manual car with a blown motor - are the heads the same on both motors? If it's just a matter of swapping cams out, no biggie, if it's the heads too, I'd rather not tear the motor down bc it has low mileage and my heads would need to get machined.

Anyone know for sure?

 

[Honcho]

The heads are the same. It is the cams that are different.

Bump from the dead!

So just to clarify - I'm thinking of swapping an auto engine into a manual car with a blown motor - are the heads the same on both motors? If it's just a matter of swapping cams out, no biggie, if it's the heads too, I'd rather not tear the motor down bc it has low mileage and my heads would need to get machined.

Anyone know for sure?

 

[kookoo4nsx]

I wonder why Honda would go to the added expense of grinding new cams for the automatic. Why not just disable/bypass VVIS?

this is correct