Maximum functional HP... where is it?

[TURBO2GO]

Not a very clear cut question, but I am wondering where most people feel is the maximum amount of functional horsepower for a streetable standard body NSX.

Some have gone to 1K, but I know that past a certain amount you just are not going to accelerate faster and are just going to spin left and right. I've seen various tests in like Car and Driver where a modded ford GT with 1400 HP was not much faster than one with 750.

So if we are talking street tires.... whereabouts do you start to lose the gains and you start to just blow money. My guess is in the 500-600 neighborhood. Beyond that and you are getting into a LOT of expense, and unless you are running dedicated tires and off road, you aren't making any real gains.

500+ RWHP and you are at least at 600 crank, somwehere in the neighborhood of a ZR-1 and ahead of something like a 458. You are truly in the big boy territory. 400 seems great but you are still not quite "there". Is there a general ballpark consensus here? I've never been in an NSX faster than my own so I don't have a feel for it although I've been in other cars with that much power.

 

[mr_goat]

This is a very good question that is definitely debatable. I guess there are lots of different opinions and no real answer.

There is this company that build twin turbo Lambos and Ferraris to 1250 whp on pump gas and over 1500 whp on race gas, there are a few vids up on their site and youtube. Here is one example:

<iframe src="http://www.youtube.com/embed/nw-fgKuoiPA?feature=player_detailpage" allowfullscreen="" frameborder="0" height="360" width="640"></iframe>

It appears streetable but I don't know what tires that one is on. I think it all comes down to traction which is a combination of driver skill, tire compound and tire size and one more thing, a decent traction control system. I have read good things about the Racelogic TCS which also has launch control.

Then there is the issue with turbo lag. I imagine a 1000+ hp NSX with it's relatively small displacement (compared to lambos and F-cars) will not be as fun to drive on low rpm's as TT lambos and F-cars appear to be but here is one extreme NSX with 819 whp on E85 that Chris@SOS claims to be "... a car that not only is fast, but actually drivable with this level of power.":

http://www.nsxprime.com/forum/showpost.php?p=1488587&postcount=55

Subscribed to this thread, I am eager to hear from people who have actually experienced the different power levels in an NSX.

 

[sca037]

Obviously, the engine (with internal upgrades) will make massive power under boost.
How much of that is usable when bolted to a relatively stock driveline and chassis is another question.
Cody has shown that a stock transmission (with JDM 2-3-4 gears) is capable of at least 600rwhp, but at 920rwhp will turn 3rd into metal chunks.
Turned down to 600rwhp the trans (stock other than JDM gearing) seems up to the challenge, and since we don't do hard launches and drive it more like a road racing car the clutch, axles and other bits in the power path seem to be holding up well.
This car has a massive turbo (gt45R) so yes there's a lot of lag, but it's far from slow even below 5000rpm- where the hammer hits.
Maybe it's just me, but for a street car, a less-than-linear power curve actually adds to the fun factor of the whole driving experience.....and others that have tried it do seem to agree.
We run 275/35/18's in the rear, and like them being the weak link in the system.......it's cheap and easy to replace tires.

Brian

Lovefab turbo NSX by NSXbrian, on Flickr

 

[jorligan]

I had 610 RWHP on a Mustang dyno with around 490 torque and I agree with the statements by Brian. I could spin the tires in 3rd but with the torque coming on a little later, it was very easy to drive on the street, just watch out at 4500 RPM. I now have a 3.5 with a GT35 and although the RWHP is only 580, the torque is almost 500 but it comes on around 3500 RPM. I turned down the boost at XPO to 12 lbs but even then, I could pull hard in 4th gear.

Functionality of HP is really going to depend where you want to use it, ie which gear. If you are planning on tracking alot, a turbo setup is kinda nice because you can increase your HP with improved driving skill. Let's face it, really high HP is fun on the street but pretty useless except when screwing around or driving in 5th / 6th gear.

The other issue of high HP really comes down to the clutch. I have the SOS twin Carbon and I would heartily agree with SOS when they say occasional street and primarily track. It has a very short engagement point and is really on/off.

 

[mrbozo1]

Dont you think that question really depends on the driver? Some drivers could handle 1000 hp and others get in trouble at 400? The car has something to do with the setup. but as you have probably seen we are all different.:biggrin::wink::frown::redface::tongue::smile:

 

[TURBO2GO]

No I don't want to bring the driver factor into it. Some shouldn't drive at all so where does that get me.

I also don't want to get into something that is not functional on the track. The idea of being able to regulate boost and power levels via a wastegate is great.

Heavy stiff clutches... I would say that's not really streetable. So if that becomes an absolute necessity at some level, then I would say the sweet spot is below that level. I understand the whole need for a built motor at much above 400 with most systems. And I understand that's debatable below or above that for some. Taking that out of the equation too.

Where is that sweet spot where you sorta say the chassis on a street driven and part time track car really is getting close to its useful limits?

 

[jorligan]

No I don't want to bring the driver factor into it. Some shouldn't drive at all so where does that get me.

I also don't want to get into something that is not functional on the track. The idea of being able to regulate boost and power levels via a wastegate is great.

Heavy stiff clutches... I would say that's not really streetable. So if that becomes an absolute necessity at some level, then I would say the sweet spot is below that level. I understand the whole need for a built motor at much above 400 with most systems. And I understand that's debatable below or above that for some. Taking that out of the equation too.

Where is that sweet spot where you sorta say the chassis on a street driven and part time track car really is getting close to its useful limits?

600 RWHP with around 450 torque. With this setup, you might be able to use a more streetable clutch. The previous single disc RPS had a very smooth engagement but was very firm. It handled torque well. There is a modification on the Dali site which reportedly changes the firmness by changing the pivot point of the clutch pedal. The SOS carbon-cabon is very soft, actually softer than the clutch on my 996 turbo but the engagement is off - on. Anything higher than 600 RWHP could be a clutch issue. I am not sure about the clutch on the Lovefab car, will have to discuss with Cody or Brian.

 

[TURBO2GO]

So what is the HP where the clutch is smooth and not with a ton of effort?

 

[E-Nough Logic]

I have the SOS twin carbon clutch capable of holding 700ftlbs, and IMO this clutch is very light, and comparable engagement to other single plate clutches I've used in the past on other cars. I would put the limiting factor on traction and/or drivetrain reliability. Traction seems to vary greatly, while some at 550+ have no issues, many at sub-500whp have traction issues. Proper wheel and tire selection as well as staged boost can help keep the car safe at higher torque levels.

 

[SOURCE 1]

I'll chime in.. I've been in NSX's from stock to 800hp. The two turbo cars I have had were in the 425-450 range in WHP. Honestly you have to have a driver factor in there because people drive differently. I tend to like the fact that with 450ish HP you can still beat on the throttle in corners and drive the car like an nsx was designed for. Seems to be anything more you have to start changing the way you drive your car to handle the power. Some people like to have to change the way you drive the car to handle more power.

So to ME I think 450 at the wheels is just about perfect for the car. It "can" be faster but it changes the "nsx" experience to me.

 

[mrbozo1]

Well then with the driver out of the equation. My car has two settings,one for 630 whp and one for 435 whp. Because I run e-85 I can run either setting on the track or on the street, and have run both on the track and on the street. From my experiences 630 whp on the street is a little tricky,but manageable. On the other hand 435 on the street is very easy to control and is fast enough to contend with most cars. My car previously had 500 whp on the street and looking back that was about perfect. So to answer your question in my opinion 500 is about right on the street. When I had 500 whp on the street I also had the RPS single disc clutch that was definitely a very heavy clutch but had very smooth engagement. Now I have the RPS carbon-carbon clutch which is not a very user friendly clutch.

 

[mrbozo1]

I'll chime in.. I've been in NSX's from stock to 800hp. The two turbo cars I have had were in the 425-450 range in WHP. Honestly you have to have a driver factor in there because people drive differently. I tend to like the fact that with 450ish HP you can still beat on the throttle in corners and drive the car like an nsx was designed for. Seems to be anything more you have to start changing the way you drive your car to handle the power. Some people like to have to change the way you drive the car to handle more power.

So to ME I think 450 at the wheels is just about perfect for the car. It "can" be faster but it changes the "nsx" experience to me.

Well that confirms it. Somewhere between 450-500 whp is about right.

 

[SOURCE 1]

Well that confirms it. Somewhere between 450-500 whp is about right.

:tongue:


Actually I will add another thought.. My opinion is for a turbo car. Supercharged I think it can be more. Because the power is not as violent. I have been lucky enough to have a good amount of seat time in a 555rwhp Supercharged NSX and it feel absolutely perfect. VERY manageable in all aspect of driving. I have not been in a more powerful supercharged car so I can not comment on higher HP than that. I think it's simply due to the fact there is not a rush of power like turbo cars.

 

[TURBO2GO]

The clutch is huge to me. What clutch is truly comfortable and what can it hold? I'm still on my factory clutch with a CTSC and it's fine. Comfortable... I wish the flywheel was lighter. The engine doesn't respond fast enough for me on heel and toe downshifts often. A bit quicker would be a lot better for me, but the clutch is great. So at 500, is there such a thing as a comfortable clutch? If not, what about at 450?

 

[SOURCE 1]

The clutch is huge to me. What clutch is truly comfortable and what can it hold? I'm still on my factory clutch with a CTSC and it's fine. Comfortable... I wish the flywheel was lighter. The engine doesn't respond fast enough for me on heel and toe downshifts often. A bit quicker would be a lot better for me, but the clutch is great. So at 500, is there such a thing as a comfortable clutch? If not, what about at 450?

I'm running the SOS sport clutch. Feels great. Good pedal and no issues even on hard launches at the drag strip with heated up R888's. Drive-able in traffic yet holds the power needed.

 

[TURBO2GO]

I'm running the SOS sport clutch. Feels great. Good pedal and no issues even on hard launches at the drag strip with heated up R888's. Drive-able in traffic yet holds the power needed.

That's only good for 350 though..

 

[SOURCE 1]

That's only good for 350 though..

350tq yes. I am not at that point.

 

[BATMANs]

I feel that 400rwhp is a SOS SC car is good but with sticky and wider tires the NSX can probably be at 450rwhp and still streetable and very fast for the large majority of people.

 

[jorligan]

So what is the HP where the clutch is smooth and not with a ton of effort?

Modified RPS single disc or the SOS Sport 350 / 400. I would agree with MrBozo regarding the clutches. He and I have the exact same experience, original RPS which was very smooth and could hold 450 torque as well as 600 RWHP (Blodi has my old one and he reports excellent success at the drag strip and track) and I currently have the SOS 700 which is the same as the RPS carbon-carbon. Soft pedal but somewhat difficult engagement with shudder, stalling or chirping of the tires. I think that I get a good engagement around 10% of the time, stall 30% of the time, Chirp the tires 10%, and somewhere in between the remainder. It has become more difficult to use since I got the SOS modified AEM vs when I was using an FIC.

 

[RYU]

So you're basically asking for a NSX-R. To me "streetable/trackable" means this.

1. Friendly and tame clutch engagement
2. Street friendly tires (e.g. RE11, StarSpecs, AD08, V12s etc)
3. No crazy aero mods going much further than NSX-R aero goodies
4. Comfortable yet supportive seats
5. The most important one for me. You're friend or neighbor must be able to drive the car and be impressed but not be scared or come close to crashing it.

Therefore, HP for this car should be 350-400 whp otherwise you'll be forced to upgrade all or one of the above criteria and therefore fail my own personal "streetability" test. I believe anyone can build a fast car. It's preserving the balance and duality that's difficult. You don't need massive power to be fast.

The Spoon NSX does 350-400whp on a single turbo, DG-5 suspension, 17/17 Prodrives, no power steering, and lightened chassis. Though I would do w/o the GT body kit personally. That's Tyler McQuarie driving at one of our local small tracks.
<iframe width="420" height="315" src="http://www.youtube.com/embed/IjRNW1Wj4lU" frameborder="0" allowfullscreen></iframe>

 

[L_RAO]

RYU - I completely agree with your assessment. I am trying to build a 300-320 wHP NA motor, with a 2600-2700 lb. car. That should make for a fun combo.

 

[TURBO2GO]

Well the thread subject is maximum functional HP. Note the word maximum. I have 350 now I think the car can DEFINITELY handle more. Another 100 sounds perfectly reasonable to me. Even on the same clutch I feel if you are careful with it. A it sounds like the whole thing is predicated by the clutch? I am definitely not into stalling 30% of the time and chirping the tires 10% of the time.

 

[bruce91nsx]

I'll chime in.. I've been in NSX's from stock to 800hp. The two turbo cars I have had were in the 425-450 range in WHP. Honestly you have to have a driver factor in there because people drive differently. I tend to like the fact that with 450ish HP you can still beat on the throttle in corners and drive the car like an nsx was designed for. Seems to be anything more you have to start changing the way you drive your car to handle the power. Some people like to have to change the way you drive the car to handle more power.

So to ME I think 450 at the wheels is just about perfect for the car. It "can" be faster but it changes the "nsx" experience to me.

I agree.. I have a 2.3 liter supercharger on a built SOS engine, and it is completely smooth coming out of corners on a track. I know how much fun it would be to spin wheels through all the gears, but at 450 rwhp it is completely sticky with Toyota r888 tires on street/track. ...also dynoed at 347 tq
-bruce

 

[brandonsan]

Well the thread subject is maximum functional HP. Note the word maximum. I have 350 now I think the car can DEFINITELY handle more. Another 100 sounds perfectly reasonable to me. Even on the same clutch I feel if you are careful with it. A it sounds like the whole thing is predicated by the clutch? I am definitely not into stalling 30% of the time and chirping the tires 10% of the time.

When I had 400 WHP it wasn't enough. The chassis could handle so much more. My guess is 500 would be perfect.

 

[cptnsx]

I feel that 400rwhp is a SOS SC car is good but with sticky and wider tires the NSX can probably be at 450rwhp and still streetable and very fast for the large majority of people.

This is the correct answer, if you mean streetable in ALL GEARS. Any more power and you will have to feather the throttle in 1st gear. Before I got my Star Specs, I thought that 420rwhp was too much because I do like to hammer my throttle in 1st gear. The tires would spin and the car would wriggle and I would have to modulate 1st gear some. With the Star Specs, none of that. I feel I could have another 30 to 40rwhp and still treat the throttle like an on/off switch.