how to get around 300+ rwhp NA?

[BATMANs]

I gotta say Bat your posts of late are sounding more on point/relevant/and civil. Of course still sprinkled with your fascination of medical oddities/ male -female genital issues.Well done.

As of late?

 

[L_RAO]

As an FYI, I am really excited about the potential of HyTech's N/A kit, if/when it ever happens.

Their header design alone, with the anti-reversion chambers & (proprietary) collector design, should/could be worth up to 10 wHP over any other design that 's currently out there.

Because of how well their headers worked on F22s and K20/K24s, they were actually able to run "smaller" cams (i.e., there was nothing gained by going to "bigger" cams). Speaking of which, I'm still fascinated (though its luster has worn off) of the Toda cams.

John's general impression of the C motors is that it is very much like the B, with "heads that flow more than most people will ever need." Speaking to that, I still haven't seen anything that has proven that the volume & velocity of airflow through the C heads improves with headwork.

As to my RDX injector project, ProSpeed is still working on the VTEC map that seems to be rejecting the bigger injectors. I do have a backup plan to go with the AEM EMS, but I still want to see if ProSpeed can come up with a chip that allows for NA1 owners to do the swap "affordably."

RDX injectors + hardware = $400
ProSpeed chip = $350

vs.

AEM EMS Series 2 + harness = $1500
AEM UEGO = $500
Optional (AFR gauges, either run 2 in the car or just have the tuner monitor it at their shop)
Tuning

 

[JLCoolman]

great summary Honcho, you hit the nail on the head

fwiw my now departed 96 engine with the cams ect did run lean above 7k rpm,that was with oem fueling, ecu ect.

yikes!

As an aside I think we have a subset of owners who actualy won't be satisfied with thier car until they have modded it to be unreliable and finnicky,kinda like Dave(turbo2go). It is a kooky way of adding more exoticness to the otherwise rocksolid nsx.

I'm trying to refrain from going down that road with the NSX, as I've already gone of the deep end with my Civic, lol.

This thread should really be:
2. renamed " How can i get the most HP outta my NSX without FI and/or cracking open my block?

+1
I know I've talked about a lot of randomness in my posts so far in this thread, but that title sums up what I aim to do, as did Honcho's post.

Agreed. There should be a "Natural Aspiraton Power" Subforum for threads like these.

I always wondered why there wasn't a Naturally Aspirated subforum on Prime for the NSX which is N/A in its purest form and probably most appreciated when N/A tuned.

 

[Ric]

^^^^ is that section called " general owner discussion" ?

 

[greenberet]

Injectors. Stock injectors are running 95%+ duty cycle at max RPM's so larger injectors are needed to maintain stoichiometric(sp?) balance.

Since 1995, my NSX has been running Comptech’s high-lift camshafts, ported cylinder heads milled for a slightly higher compression ratio, a polished intake manifold, plus the usual I/H/E mods. I had a chip custom-programmed for my car’s PGM-FI and the guy who did the tuning never mentioned that my stock 3.0 injectors are close to maxing out their duty cycle.

Aftermarket ECU, which means pre 1995 car. Cannot adjust timing and fuel enough to safely go high HP.

My NSX has been completely reliable for the past 17 years with the modifications it has and a chip programmed for the stock ECU. I was present while my engine management chip was being programmed with the car on a dyno and the guy who did the tuning never mentioned that the timing and fuel were being limited by the stock ECU. It would be interesting to get ProSpeed's or sr5guy's insights into the injectors' duty cycle and the limits the ECU places on ignition timing. The PGM-FI with a custom chip seems to work well for my engine.

Throttle body, heads and intake are good enough stock.

I’ve heard from informed sources that the stock throttle body does start to choke the engine when you [edit: get to about 250 rwhp]. If you look at the cross section of the intake tract from the intake ports all the way through to the intake snorkel, the throttle body does have a smaller effective cross section than the things upstream and downstream of it. Also, the intake opening of the stock intake snorkel is smaller than its exit so that does not sound ideal from a flow perspective, either.

 

[GhettoRacer]

Since 1995, my NSX has been running Comptech’s high-lift camshafts, ported cylinder heads milled for a slightly higher compression ratio, a polished intake manifold, plus the usual I/H/E mods. I had a chip custom-programmed for my car’s PGM-FI and the guy who did the tuning never mentioned that my stock 3.0 injectors are close to maxing out their duty cycle.


My NSX has been completely reliable for the past 17 years with the modifications it has and a chip programmed for the stock ECU. I was present while my engine management chip was being programmed with the car on a dyno and the guy who did the tuning never mentioned that the timing and fuel were being limited by the stock ECU. It would be interesting to get ProSpeed's or sr5guy's insights into the injectors' duty cycle and the limits the ECU places on ignition timing. The PGM-FI with a custom chip seems to work well for my engine.


I’ve heard from informed sources that the stock throttle body does start to choke the engine when you go above about 235 rwhp. If you look at the cross section of the intake tract from the intake ports all the way through to the intake snorkel, the throttle body does have a smaller effective cross section than the things upstream and downstream of it. Also, the intake opening of the stock intake snorkel is smaller than its exit so that does not sound ideal from a flow perspective, either.

Do you have any dyno results for your NSX and/or drag strip results?

 

[L_RAO]

greenberet: How many miles have you put on the Comptech valvetrain? And, have you inspected the cams/cam journals for wear?

 

[greenberet]

Do you have any dyno results for your NSX and/or drag strip results?

I haven’t taken my car to a drag strip but I have put it on dynos. However, I didn’t do a baseline dyno run without modifications and immediately thereafter do another run with the modifications, so I don’t think the dyno figures are worth very much on their own. A Bosch FLA-203 dyno said my car puts a corrected 201.6 kW to the wheels, or about 270 rwhp. A Clayton Hydrokinetic chassis dyno said my car puts out 408 rwhp. Uh… yeah.

However, that Clayton dyno had previously measured a stock NA1 and said that puts out 304 rwhp. If my car put out 34.1% more than a stock NA1 and a stock NA1 really puts out 235 rwhp, that would give mine about 315 rwhp.

When I got my car modified in the Spring of 1995, I bought all the horsepower-related modifications Comptech offered. In that configuration, Comptech said the engine would produce 358 crank hp, or about 312 rwhp – which is pretty close to the 315 rwhp the Clayton dyno implied mine put out.

Looking at it another way, when my avatar picture was taken, the car had engine modifications but no undertrays. With a stock 5-speed transmission and 245/40 17 rear tires, it pulled to an indicated 8000 rpm in one direction on the Autobahn and 8050 in the other. If there were no tire slip, if the tachometer were perfectly accurate, etc. 8025 rpm should have been 188 mph given the gearing. However, since there must have been some tire slip, etc., the “real” two-way top speed was a bit lower.

According to Honda, a stock NA1 is supposed to have a top speed of 168 mph and according to the NSX Prime Wiki, they put out about 235 rwhp in stock form. With 270 rwhp, the same car should be able to go about 176 mph. My car went faster than that, so I think the 270 rwhp dyno figure was probably too low. With 408 rwhp the same car should be able to go 199 mph so that dyno figure is way too high. With 312 to 315 rwhp, the same car should be able to go about 184 or 185 mph so those figures seem to fit the top speed I’ve observed in my car pretty well.

greenberet: How many miles have you put on the Comptech valvetrain? And, have you inspected the cams/cam journals for wear?

I had the full mods installed at 37,834 miles and now my car has 138,683 miles, so the modified valvetrain has about 101,000 miles on it. I believe the camshafts have the stock low-speed lobes and that Comptech only modified the high-speed lobes. At the last service, I asked the mechanic how the high-speed lobes look and he said he couldn’t see any wear on them. The camshafts haven't been removed to measure them or check the journals, however.

 

[JLCoolman]

I had the full mods installed at 37,834 miles and now my car has 138,683 miles, so the modified valvetrain has about 101,000 miles on it.

That is awesome!!!

 

[GhettoRacer]

I haven’t taken my car to a drag strip but I have put it on dynos. However, I didn’t do a baseline dyno run without modifications and immediately thereafter do another run with the modifications, so I don’t think the dyno figures are worth very much on their own. A Bosch FLA-203 dyno said my car puts a corrected 201.6 kW to the wheels, or about 270 rwhp. A Clayton Hydrokinetic chassis dyno said my car puts out 408 rwhp. Uh… yeah.

However, that Clayton dyno had previously measured a stock NA1 and said that puts out 304 rwhp. If my car put out 34.1% more than a stock NA1 and a stock NA1 really puts out 235 rwhp, that would give mine about 315 rwhp.

When I got my car modified in the Spring of 1995, I bought all the horsepower-related modifications Comptech offered. In that configuration, Comptech said the engine would produce 358 crank hp, or about 312 rwhp – which is pretty close to the 315 rwhp the Clayton dyno implied mine put out.

Looking at it another way, when my avatar picture was taken, the car had engine modifications but no undertrays. With a stock 5-speed transmission and 245/40 17 rear tires, it pulled to an indicated 8000 rpm in one direction on the Autobahn and 8050 in the other. If there were no tire slip, if the tachometer were perfectly accurate, etc. 8025 rpm should have been 188 mph given the gearing. However, since there must have been some tire slip, etc., the “real” two-way top speed was a bit lower.

According to Honda, a stock NA1 is supposed to have a top speed of 168 mph and according to the NSX Prime Wiki, they put out about 235 rwhp in stock form. With 270 rwhp, the same car should be able to go about 176 mph. My car went faster than that, so I think the 270 rwhp dyno figure was probably too low. With 408 rwhp the same car should be able to go 199 mph so that dyno figure is way too high. With 312 to 315 rwhp, the same car should be able to go about 184 or 185 mph so those figures seem to fit the top speed I’ve observed in my car pretty well.

I had the full mods installed at 37,834 miles and now my car has 138,683 miles, so the modified valvetrain has about 101,000 miles on it. I believe the camshafts have the stock low-speed lobes and that Comptech only modified the high-speed lobes. At the last service, I asked the mechanic how the high-speed lobes look and he said he couldn’t see any wear on them. The camshafts haven't been removed to measure them or check the journals, however.

That sounds about right...

Any dyno sheets online? I would like to see your torque curve. Also, what rpm limit do you use? Are you running stock bottom end?

 

[dablackgoku1234]

Are there any "cheap" engine performance mods that can be done while the engine is out for a timing belt/water pump service?

 

[Honcho]

Degree the cams so you are getting max performance out of them. Also, ATI damper and light flywheel.

Are there any "cheap" engine performance mods that can be done while the engine is out for a timing belt/water pump service?

 

[dablackgoku1234]

I looked at SOS's site, do these do anything in terms of adding performance?

Valve springs: http://scienceofspeed.com/products/...s/NSX/ScienceofSpeed/valve_springs_retainers/

LMA: http://scienceofspeed.com/products/engine_performance_products/NSX/ScienceofSpeed/LMA/

 

[greenberet]

Any dyno sheets online? I would like to see your torque curve. Also, what rpm limit do you use? Are you running stock bottom end?

The dyno sheet showing 270 (corrected) rwhp is here: (Bosch) NSX Dyno sheet 1997.pdf. The Bosch dyno didn’t print out the torque curve, but you could calculate it based on the horsepower curve. The dyno sheet showing 408 rwhp isn’t online but if you PM me your email address, I can send it to you. I can’t attach the .pdf file to the thread myself because my attachment limit has been reached and I can’t upload it to my NSX Prime photo album because that doesn’t accept .pdf or .zip files.

Regarding the rpm limit: I asked the guy who programmed the chip to keep the rev limit stock so that the engine would have a long, healthy life. And yes, the bottom end is completely stock and has never been opened. So my engine still has the stock pistons, rings, cylinders, connecting rods, crankshaft, bearings, etc. And also the stock valves, valve springs, retainers, catalytic converters, and throttle body.

… do these do anything in terms of adding performance?

Short answer: no.

Long answer: stiffer valve springs keep the valves in contact with the cams even if you increase the engine speed, the lift of the cams, etc. Those things can help you make more power and stiffer valve springs can make them possible. The downside is that stiffer valve springs increase friction in the valvetrain, causing increased parasitic losses and decreasing camshaft life. Ideally, you want your valve springs to be as stiff as necessary but not stiffer than that. Aftermarket valve springs can also allow for more valve lift before they “bind”. If you leave your rev limit where it is and keep your stock camshafts, stiffer valve springs that allow for more lift won’t increase horsepower. Probably the opposite.

The lost motion assemblies simply keep the high-speed cam followers lightly pressed against the high-speed cams at low engine speeds, preventing them from rattling. The original oil-filled LMAs are prone to sticking as they age, causing a kind of rattle in the engine. Honda got rid of that problem by simplifying the design of the LMAs, turning them into little springs. The SoS kit allows you to run the latter rattle-proof LMAs in earlier NSXs. They'll help your engine sound better, but they won’t increase horsepower.

 

[dablackgoku1234]

Thanks for the detailed explanation! Will look into degreeing the cams and an ATI damper. I probably won't be touching the clutch/flywheel yet. Will replace the whole assembly with an SOS sport clutch when this OEM one goes.