Increasing automatic hp?

[dcrandon]

Hello everyone,

I'm still in the process of researching my first purchase of a NSX. I'm taking it real slow like everyone suggests.

My question is simply, can the hp of the automatic be upped to the same as for a manual by something simple like an ECU exchage or whatever?

I ask because a steering wheel mounted shift is what I've always thought was totally cool. I know that's its sort of a semi-auto, in that I don't use the clutch.

I ask because I drive about 25-30000 miles per year, some in stop and go traffic. I've driven manual shift cars exclusively for the last 20 years. But last year I had to drive my wifes Accord for a few months, and, I tell ya, it sure was nice not to have to shift all the time in stopandgo traffic here in LA.

I wonder if Acura would have sold more automatics if there wasn't such a big performance drop...

David

 

[nsxtasy]

can the hp of the automatic be upped to the same as for a manual by something simple like an ECU exchage or whatever?

No.

I wonder if Acura would have sold more automatics if there wasn't such a big performance drop...

I don't think it would have made a bit of difference. The big performance drop is primarily because of the automatic transmission, not because of the difference in horsepower from the engine.

If you want an automatic, then get an automatic and live with the slightly lower level of acceleration. (Remember, it still has all the handling of the NSX, and you can make whatever suspension/brake/chassis modifications to an automatic car without worries.) If you want the acceleration performance of the five speed (with or without performance modifications), then get the five speed.

 

[theman1990]

Well.... the HP difference is due to the different cams, and the 500 rpm lower redline. Headers and exhaust will really wake it up, as it did my 96 auto.

People fail to realize how much a difference the cams and lower redline make. The "upside" of the cams is they supposedly make more torque thru the RPM band.

 

[nsxtasy]

Well.... the HP difference is due to the different cams, and the 500 rpm lower redline.

The peak horsepower is at 7100 RPM, and horsepower is falling by the time the revs reach the 7500 RPM redline of the automatic. Thus the horsepower difference is not due to the redline.

 

[ETLMD]

If you have to convince yourself or justify an automatic, I think you'll regret it.

 

[theman1990]

The peak horsepower is at 7100 RPM, and horsepower is falling by the time the revs reach the 7500 RPM redline of the automatic. Thus the horsepower difference is not due to the redline.

Correct... again... because of the CAMS. They make peak power at the shift point of the automatic. What is the HP at 7100 RPM of a manual stock engine?

 

[NSXGMS]

Headers and exhaust will really wake it up, as it did my 96 auto.

Although this is your personal experience I find that very hard to believe. Do you have dyno results to support this?

The exhaust system on an auto is very free-flowing. It's the engine itself which is maxed at 252 hp. There should be no exhaust bottleneck whatsoever on an auto engine. AFAIK the exhaust system is the same as the 270hp version so clearly 252 hp isn't pushing the limits of the exhaust system.

 

[theman1990]

Well before the headers/exhaust, it NEVER broke the tires loose on the 1-2 shift, now it does every time. Sounds like a difference. Also, given that line of thinking, then for anything below 270 HP, the exhaust is worthless????

 

[nsxtasy]

What is the HP at 7100 RPM of a manual stock engine?

270 hp (for the 3.0-liter).

 

[NSXGMS]

Well before the headers/exhaust, it NEVER broke the tires loose on the 1-2 shift, now it does every time. Sounds like a difference. Also, given that line of thinking, then for anything below 270 HP, the exhaust is worthless????

If "worthless" is that one should not expect a power increase with aftermarket headers/exhaust on an auto that is true. If a different sound is what you're looking for then go aftermarket.

I'm sure the aftermarket exhaust companies will try to tell you it's not worthless...

The OEM exhaust and manifold do not bottleneck an auto engine. I have heard of no one who has installed aftermarket headers/exhaust on an auto that has dyno (not the butt-dyno) numbers showing power increases. If you can find some data contradicting that I'd be more than happy to acknowledge it.

It is my understanding that the cams and ECU do all the bottlenecking on the 252hp motor. It's the engine itself which is limited to 252hp. Not so for the 270hp version. That engine is not limited to 270hp. It is being limited to 270hp.

 

[ACCD]

I drive an auto because of our traffic here in dallas, among other things. All I've done is exhaust and the auto shifts hard and fast. (did make a big difference) Stock to stock there probably isn't enough difference to suffer with a stick in heavy traffic. However, if you want a "killer" then a stick will give you the most flexibility and allow you push out as much horsepower as your check book can handle.. The auto is still a great car, fun to drive and quick. I wouldn't be afraid to go FI and most likely will. It's a personal choice based on needs. There are sources for a beefed up transmission and torque converter if you get over 400HP.. However, I personally feel that I could go another 40 horses without danger..providing I don’t do consistent power braking burnouts or track the car. There's lots of ways to go fast... as they say..you "get there in a car".... you ARIVE in an NSX..It’s just a great, well balanced ride which ever the choice.

ac

 

[nsxtasy]

I wouldn't be afraid to go FI and most likely will. It's a personal choice based on needs. There are sources for a beefed up transmission and torque converter if you get over 400HP.. However, I personally feel that I could go another 40 horses without danger..providing I don’t do consistent power braking burnouts or track the car.

Mark Basch's experience with customer cars who had modifications installed on their automatics and blew their transmissions might make you re-think your "feelings".

 

[dcrandon]

If you have to convince yourself or justify an automatic, I think you'll regret it.

That's what I'm afraid of. Why did Honda dumb down the engine for the auto? Surely it couldn't be because they thought the tranny couldn't take more power or torque?

 

[topman2005]

Mark Basch's experience with customer cars who had modifications installed on their automatics and blew their transmissions might make you re-think your "feelings".

Are those transmissions upgraded by level 10?

 

[nsxtasy]

Why did Honda dumb down the engine for the auto? Surely it couldn't be because they thought the tranny couldn't take more power or torque?

That's exactly why they reduced the power for the automatic.

Which ought to make you think twice before doing power mods without tranny mods...

 

[popsicle]

That's exactly why they reduced the power for the automatic.

Which ought to make you think twice before doing power mods without tranny mods...

all you'd need to do is beef up your tranny. and all you need to do that is the checkbook. a rule with going FI in any platform is to address all the related areas, braking, supsension, drivetrain etc. so i don't see why anyone would not consider beefing up the tranny regardless. it could fail in an auto or 5spd or 6spd. doesn't matter what car it is. yes there are threshold numbers but i like to get everything properly done.

 

[ACCD]

Mark Basch's experience with customer cars who had modifications installed on their automatics and blew their transmissions might make you re-think your "feelings".

Doubt it.


AC

 

[sahtt]

Transmissions have no influence on the power the engine produces. It does produce less whp compared to a 5/6spd due to increased drive train loss.

However, Honda had horrible automatic transmissions in the 90's. Besides the 90-93 accords and some civics, it has been Honda's weakness for many years. It began with the mid 90's accords and peaked with the horrible TL/CL problems that really blemished Honda's reputation in the late 90's.

I have little doubt the engine was detuned in order to add longevity/durability to the transmission. If you do upgrade the cams and adjust the ECU to reach "stock" power levels there is a chance the transmission's durability will be compromised sooner than later. Adding further power will continue to put extra strain on it. What differentiates between the transmissions that last 6 months and 6 years is how they are driven. A 500hp auto nsx that never sees above 10% throttle going to the grocery store and back is going to last longer than a 350hp auto that is driven hard regularly.

For this reason, I'd either be satisfied with the given 250hp, upgrade the transmission and then add power, or simply accept the financial/annoyance risk that comes with driving an auto above stock power hard. That or get a manual :biggrin:

 

[ediddynsx]

Use this for instant power

 

[nsxtasy]

Mark Basch's experience with customer cars who had modifications installed on their automatics and blew their transmissions might make you re-think your "feelings".

Doubt it.

Then you're wrong, as you can see for yourself, in this post. His words:

Ray, for starters, the BBSC is not available for the automatic, because I won't make it because it won't last. The tranny, that is. I have rebuilt three NSX automatica and let me tell you, though they have several innovations not found in other trannies, not even other Honda trannies, it is NOT NOT NOT
up to the task of handling any more power than it already does. That's "NOT", btw.
That is why the auto engine is detuned from the manual counterpart.
I have had this discussion with the engineers at CT, and they disagree though not with any vigor. They do sell a kit for the auto shifter, but it only makes anout 65 hp. My opinion based on the overhauls, and other information and opinions that I have is, don't do it.

Of course, he has only worked on hundreds of NSXs, so what does he know, right?

 

[dcrandon]

That's exactly why they reduced the power for the automatic.

Which ought to make you think twice before doing power mods without tranny mods...

It's surprising to me that Honda decided not to produce a auto tranny that could handle more that 250 lbft of torque. Even back in the 90's it wasn't that much...

 

[ACCD]

Transmissions have no influence on the power the engine produces. It does produce less whp compared to a 5/6spd due to increased drive train loss.

However, Honda had horrible automatic transmissions in the 90's. Besides the 90-93 accords and some civics, it has been Honda's weakness for many years. It began with the mid 90's accords and peaked with the horrible TL/CL problems that really blemished Honda's reputation in the late 90's.

I have little doubt the engine was detuned in order to add longevity/durability to the transmission. If you do upgrade the cams and adjust the ECU to reach "stock" power levels there is a chance the transmission's durability will be compromised sooner than later. Adding further power will continue to put extra strain on it. What differentiates between the transmissions that last 6 months and 6 years is how they are driven. A 500hp auto nsx that never sees above 10% throttle going to the grocery store and back is going to last longer than a 350hp auto that is driven hard regularly.

For this reason, I'd either be satisfied with the given 250hp, upgrade the transmission and then add power, or simply accept the financial/annoyance risk that comes with driving an auto above stock power hard. That or get a manual :biggrin:

well put.

It's a balance between needs/wants/dollars

ac

 

[Hal_396]

From what I understand, It's heat that causes 9 out of 10 tranny failures. If this is the case with the NSX tranny's, then it wouldn't be that big a deal to add a cooler or three. At the very least that's what I would do with my auto before I did anything to the engine.

 

[sahtt]

From what I understand, It's heat that causes 9 out of 10 tranny failures. If this is the case with the NSX tranny's, then it wouldn't be that big a deal to add a cooler or three. At the very least that's what I would do with my auto before I did anything to the engine.

This has some truth to it but also can be misleading.

Let's say a manual transmission fails; is it primarily due to heat as well? No, usually it's due to greater force in the form of torque than the design of the gears/teeth on the gears can support without being grounded smooth or simply shattering/breaking. Obviously it can be more complex than that, but that's the foundation of the problems. It can be caused by driver error in the form of a miss-shift or partial shift resulting in damaging friction, or it can simply be that the materials, the thickness, or their assembly cannot withstand a given amount of torque-regardless of the surrounding conditions.

It is true most well built manual transmissions can handle a huge amount of power if it's not transfered at all during a shift; as in simply WOT during 5th gear. On the other side, frequent hard shifting can cause a stock car's manual gearbox to begin to disintegrate within a few years.

What I'm trying to get at is the automatic also has these issues, but they are further compounded by the increased number of moving parts and complexity/fragility of its design. So regardless of how "cool" you manage to "keep it", the transmission has a given limit to the amount of torque it can transfer to the drive shaft; which is relatively low. When you "beef up" an auto, you are replacing various components such as gears/clutches with higher capacity/stronger parts.

Combine the above with the fact the automatic transmission's shifting characteristics are much harder to predict and manipulate and it's an up hill battle; not to mention you can upgrade the clutch etc. to fortify the manual which is not possible without a high cost on an auto. Whereas it would not be too difficult to shift an overextended manual transmission gently, the automatic does not have this option in most cases, especially when you actually want to use the power.

Cooling the auto transmission will add to its durability, but will NOT increase the ultimate amount of torque it can transfer before basically self-destructing.

 

[Synthesis]

Transmissions have no influence on the power the engine produces. It does produce less whp compared to a 5/6spd due to increased drive train loss.

However, Honda had horrible automatic transmissions in the 90's. Besides the 90-93 accords and some civics, it has been Honda's weakness for many years. It began with the mid 90's accords and peaked with the horrible TL/CL problems that really blemished Honda's reputation in the late 90's.

I have little doubt the engine was detuned in order to add longevity/durability to the transmission. If you do upgrade the cams and adjust the ECU to reach "stock" power levels there is a chance the transmission's durability will be compromised sooner than later. Adding further power will continue to put extra strain on it. What differentiates between the transmissions that last 6 months and 6 years is how they are driven. A 500hp auto nsx that never sees above 10% throttle going to the grocery store and back is going to last longer than a 350hp auto that is driven hard regularly.

For this reason, I'd either be satisfied with the given 250hp, upgrade the transmission and then add power, or simply accept the financial/annoyance risk that comes with driving an auto above stock power hard. That or get a manual :biggrin:

THANK YOU.... damn, i know you auto guys don't want to hear it when it comes to people telling you to buy an manual, which is understandable

but when you're talking about tuning a honda with an automatic transmission... all i have to say is good luck, and don't be too proud to let us know when the thing dies on you... :frown: