Is it worth modifying an Auto NSX?

[rcarlos]

Hey Kiwi,

Where did you get the Sport-shift model from and what year is it? I live in Wpg. and have been looking for one for a long time. I have a 91 auto.

Edit: It's my own fault I don't have a newer NSX. There was a Sport-shift for sale in Van. but I am still making BMW payments and 80k was more than I could afford.

[This message has been edited by rcarlos (edited 14 January 2002).]

 

[RyRy210]

I recently also found out the intake valves are also different in the automatic NSXs. I was thinking about changing my stock exhaust manifold & exhaust for an aftermarket one, but was asking myself many questions that I don't really know the definite answer to. It has become more and more aparent that the automatic was designed differently from the manual. I took a '95 NSX manual and a '95 NSX automatic, and the acura dealer noticed these 2 models DO NOT share the same exhaust and exhaust manifold (part #s are different). Even in '97 with the 3.2L engine and headers, I would think Honda could slap just the new OEM headers on the automatic NSX while retaining the 3.0L engine and gain some hp, but why didn't they? Why is it still rated 252hp after a decade? Why does the new models STILL use a cast iron exhaust manifold? Why does an automatic car and manual car with the same model year have different exhaust components? My guess is that the tranny simply can't handle any more horsepower than it already has, even an OEM '97+ header might put it over the tranny's threshold. Honestly, this really sounds absurd to me, but its enough uncertainty to prevent me from modding my automatic.

Ryan

 

[ilya]

Your tranny can be reinforced to handle the power. If you are dying to modify your car, I wouldn't let that stop you. There are many other highly modified cars with auto trannys out there.

 

[mlambert890]

Originally posted by RyRy210:
components? My guess is that the tranny simply can't handle any more horsepower than it already has, even an OEM '97+ header might put it over the tranny's threshold. Honestly, this really sounds absurd to me, but its enough uncertainty to prevent me from modding my automatic.Ryan

I wouldn't worry that much. It seems enormously unlikely to me that heads/exhaust would be enough to kill the auto-tranny. Those mods just don't make a significant enough amount of power.

I'd have a *very* hard time believing that Honda put a barely adequate auto in the NSX. Handle an extra 100rwhp? No way. Handle an extra 20hp at most? I'd say yes. To be honest, I think Honda just wants to save money on the sportshifts since they figure the buyers won't mind...

By the way, in shopping for an exhaust for my 98 sportshift I was told that the 97+ exhaust is what I should be buying, so there is some difference in the newer 3.0L.

 

[RyRy210]

Originally posted by spookyp:
By the way, in shopping for an exhaust for my 98 sportshift I was told that the 97+ exhaust is what I should be buying, so there is some difference in the newer 3.0L.

I was wondering the same thing. I mean, if you have a '01 NSX automatic, would u order the exhaust/header made for a '01 NSX on comptech's website? I would think that the whole site is geared towards manual cars. That's when I started digging. I took a '95 manual and a '95 automatic, and they share different exhaust parts too! I was hoping the dealer would tell me they were the same, so when I got it I have the peace of mind that it will fit my car, now I'm not so sure what to get. I myself had a turbo automatic car that made 300+ hp to the wheels with tranny mods, but the NSX is not something I really want to experiment with. I do agree that maybe its cost savings for the '97 up automatic NSXs. I mean, a set of OEM headers is $2,444 new and a set of cast iron exhaust manifolds is around $400 new. But if I took a '95 manual and a '95 NSX, both had different cast iron manifolds based on part #. Could it be the location of the auto tranny on the car that requires a different manifold to be made?

 

[mlambert890]

Not sure why the manifold would be different. On the exhaust, I'm sure though. Chris from SoS (hi Chris!) told me flat out that the 1997+ sportshift would require the exhaust for the 1997+ models.

 

[nsxtasy]

Mark Basch (the most experienced independent NSX tech in the country) has seen several automatic transmissions that failed due to the use of aftermarket power additions. On these forums he has STRONGLY recommended against power modifications on NSXs equipped with the stock automatic transmission.

 

[hejo]

While I don't completely disagree with the concerns I can't believe the trany will not handle the 20hp you "might" get from headers, exhaust and airbox upgrades. It just seems like that should be within the design range.

Also the research I did over the past 2 years turbos seemed to be better suited for automatics than superchargers because of how the power comes on. The other thing owners have to do is pay attendtion to the release of the pressure during shifts (up and down). For those with auto's you can do a heel-toe downshift. If you're familiar with shifter karts you'll know exactly what I mean.

Ken do you have any hard data on the number of auto trany's that have failed and why they failed. I only know of one stock auto NSX that failed because the owner put an additive in it. I heard that the original NSX Modified turbo development car was an automatic and this much power blew it out. So I agree that going beyond a ~20hp increase without doing anything to the trany is asking for trouble.

So if you're serious about adding a SC or turbo to an auto .... maybe I should be the NSX rep for levelten but they do make trany upgrades which make automatics bullet proof, http://www.levelten.com/index.html Here's what they did for Team Lexus http://www.levelten.com/pdf/grass_08_00_team_lexus.pdf

 

[nsxtasy]

Originally posted by hejo:
Ken do you have any hard data on the number of auto trany's that have failed and why they failed.

No hard data, just what Mark has posted here.

Darn, where's Forums Nazi when you need him?

 

[RACERnsX]

Originally posted by ilya:
Your tranny can be reinforced to handle the power. If you are dying to modify your car, I wouldn't let that stop you. There are many other highly modified cars with auto trannys out there.

I assume by "reinforcements" you mean upgrades or modifications to clutches etc. What kind of reinforcements can be done and who does them? Not that I doubt that they can be done but I've never seen aftermarket parts available for the auto transmission, only for the manual.

 

[hejo]

Originally posted by RACERnsX:
I assume by "reinforcements" you mean upgrades or modifications to clutches etc. What kind of reinforcements can be done and who does them? Not that I doubt that they can be done but I've never seen aftermarket parts available for the auto transmission, only for the manual.

After market specialist for autos.
---> http://www.levelten.com/store/import/items/pts/ja113_1000_honda_acura_pts.htm

---><A HREF="http://www.levelten.com/store/import/items/converter/ja313_1000_honda_acura_converter.htm" TARGET=_blank> http://www.levelten.com/store/import/items/converter/ja313_1000_honda_acura_converter.htm[/url]

Failures/problems I've heard hear on nsxprime: http://www.nsxprime.com/ubb/Forum1/HTML/000008.html
http://www.nsxprime.com/ubb/Forum1/HTML/000290.html

[This message has been edited by hejo (edited 24 April 2002).]

 

[RyRy210]

I've actually had experiences with auto tranny mods before in my automatic 3000GT in which I turbocharged, and its very labor intensive. Its not like a manual car where u can swap in a better clutch, it a complete dismantling and overhaul of the tranny. For me just finding a competent mechanic that I can really trust and give me that peace of mind that everything is ok is hard enough. Its sorta like taking apart the engine and reinforcing the bottom end, but in this case, the auto tranny.

 

[hejo]

Originally posted by RyRy210:
...For me just finding a competent mechanic that I can really trust and give me that peace of mind that everything is ok is hard enough. Its sorta like taking apart the engine and reinforcing the bottom end, but in this case, the auto tranny.

Levelten says they can do this for the NSX but I don't know if they've actually done one. They have excellent references for work they've done. The ones I contacted couldn't say anything but really high marks for them. One reference told me that they are the only firm in the US that they'd trust to even look at beefing up the NSX auto. Also if you don't want the hassel Leveltem told me they would sell a completely bullet-proof built trany that you can just drop in. I think the price was around $3500. You're right though it's a lot more work. When I did the research I came up with the cost being:
- Performance kit from Level is ~$300
- new PTS™ Torque Converter $500.
- labor ~$1600 (wild guess) based on levelten feedback on hours. I actually increased it by 50%.

Anyway no more NSX for me as I'm moving on to shifter karts for now and waiting for the market to come back so I can get my wife her horse and me my prancing horse

with an F1 shifter.

------------------
Hal - Speed of Heat
Lake Oswego, Oregon (for now)
95T Blk\Blk SportShift - sold

 

[David]

Originally posted by KIWIManson:
An auto SportsShift----is it any less an NSX. Of course not! They are still magnificant fast cars---not as good on the track as the manual OF COURSE, but for fast highway and curvy stuff the Shift is great. .......All serious racing cars have some form of auto-seqential shifters for very obvious reasons,

I don't understand your point. You are comparing an automatic transmission (viscous coupling via torque converter) to mechanical transmissions that are hydraulicly shifted. What is the connection? If you look at the transmisison on an F1 car, rally car or a paddle-shifter Ferrrari, it is the same gearbox they use on any manual transmission car, it just has a hydraulic electronically-controlled shifting mechanism connected to it. They have nothing in common with the NSX auto transmission.