NSX engine into a different car...

[goldtop]

I have a plan to put an NSX engine ('96 DBW type) into a lighter car. But the chap I was hoping would do the work already has a GT40 job that's turning out to be a nightmare.

So I found another who asked whether the NSX ECU is happy to run outside the car without any connection to all of these fancy bits. If it isn't, it would be very expensive he says - even before driveshafts, exhaust, etc. Nice to have a reality check! :)

So the Q is: can you fool an NSX ECU into thinking it's in an NSX when it isn't? Is it a matter of fixing certain sensors inputs to hi/lo, or is communication to/fro rather more complicated than that?

[havoc]

Kaz is the man to reply here, but I'd imagine, given the '96 engine is OBD-I not -II, that it's not TOO sophisticated, and can be spoofed...especially as people have been using B-, H-, K- and F-series engines in other cars for years...had a ride in an F20'd Westfield back when Anglesey Circuit was the old shape (so >10 years ago)!

Definitely worth checking though...

[drmikey]

Just run a standalone ECU like the AEM - around £1000 and would save you lots of hassle with wiring.

BTW, why put an NSX engine in another car?

[goldtop]

Just run a standalone ECU like the AEM - around £1000 and would save you lots of hassle with wiring.

BTW, why put an NSX engine in another car?

I know that an aftermarket ECU would be possible, but there's a lot of work to do after that, and I want to know about the NSX ECU as-is. If Kaz has the time to post here that'd be great, but I'm sure he's pestered with PMs by just about everyone on the forum. :) I'll ask on Prime, too, where I found at least one thread where someone was picking apart the NSX ECU code.

As for why... why not? ;) It's a rev-happy NA engine that should work well in a 980kg Stratos (replica). I thought I might be the first, but I believe there's already one driving around Japan. I'd love to find out more about that one.

[drmikey]

But with an AEM you can run twin wideband - ditch the secondary O2 sensors, no immobiliser to worry about (as they are built in with the UKDMs), no other multiplex issues to concern yourself about. Simple power and ignition circuit. I believe they even do a sub harness for the NSX.

I do like the "why not" philosophy - I know someone planning a C32 in a 911! And I've done plenty of honda swaps into a variety of cars. Just an NSX engine is relatively expensive and parts very expensive. AS STMPO has proved you can replace a C30 with a K20 lol. K20 or F20 engine can make equal or more power much more cheaply and lots of cheap parts, bellhousings, tuning mods.



I know that an aftermarket ECU would be possible, but there's a lot of work to do after that, and I want to know about the NSX ECU as-is. If Kaz has the time to post here that'd be great, but I'm sure he's pestered with PMs by just about everyone on the forum. :) I'll ask on Prime, too, where I found at least one thread where someone was picking apart the NSX ECU code.

As for why... why not? ;) It's a rev-happy NA engine that should work well in a 980kg Stratos (replica). I thought I might be the first, but I believe there's already one driving around Japan. I'd love to find out more about that one.

[havoc]

Hate to say it, but Dr M has a point - superb sound and excellent build-quality aside, the C30 isn't high-power or light-weight by modern standards, and it IS pricey to maintain/repair for a 270bhp n/a lump...

It does seem like a very nice and suitable alternative to an Alfa V6 for a Stratos kit though...can't argue with that.

[goldtop]

Thanks, guys. The reality check is much appreciated - especially the info on the UK market immobiliser.

I know there are some other V6s to consider, but I've no experience of them. The last Alfa V6 (3.2 GTA, I think) can supposedly be made to make the same power as the C30/C32, and it would be sort-of-correct for the car (Italian) and easier to fit. But is there another transverse V6 that revs so easily and so high? That's the combination I like - revs and light weight. If I didn't love this engine so much...

(Although it was a popular option among early replicas, an I4 into a Stratos doesn't float my boat!)

[Hagasan]

As far as I'm aware this age car does not have any inbuilt immobiliser in the ECU (UK wise anyway). It often had a Hamilton & Palmer (UK made) add-on immobiliser using the little fob. The H&P was marketed as a Honda immobiliser but the same unit was in a Porsche I used to own as well. My 96 car has an aftermarket Alarm/Immobilser.

I think the later cars had a factory immobilser?

[goldtop]

Hi Gary - that's interesting. for sure my '96 targa has a 3rd party fob immobiliser. It would be good if the ECU itself had no immobilising routine to stymie the plans. I read good things about AEM and had considered Emerald (who are quite local to me) but if I can do it wll a la Honda, so much the better.

[Kaz-kzukNA1]

Hi, goldtop.

If you have the will, resource and most importantly, the support from the right people/organisation, anything can be achieved. This is based on my real life:).

At the car manufacture, they are running just the engine without any other bits using the development ECU (additional I/F circuit, etc) so C30A engine can be operated with just the ECU.
If you are on the different type of test rig, then that's a different story.

However, it all depends on what you have at the moment, how far you want to go and your final goal.

If you already have the matching OEM ECU (96 DBW spec), all of the Eng Loom, Control device Tubing/Box (the black case sitting rear left corner of the engine bay), TH Pedal sensor, etc, etc, then it may save you the cost than going down the route of the aftermarket full standalone ECU.


The signal requirement is different depending on whether your OEM ECU (if you already have one) is for MT or AT model.


On DBW model, the TCS operation, cruise control, etc are done within the ECU unlike on the non-DBW model. (For the clarification, TCS calculation is done within the TCS controller but not the operation of the TH body stepping motor.)
02+ NSX-R doesn’t have TCS and it’s DBW so the engine can run without the link to the TCS.
You can’t use TCS anyway unless you implement several sensors inside the cabin/on the chassis as well as signal conditioning circuit.

Personally, I don’t like the software delay/setting on DBW model (on purposely applied for the standard NSX models apart from NSX-R) so if I’m doing this, I’ll swap the whole intake manifold inc. the TH body with the non-DBW one and use non-DBW spec ECU.
Several owners in Japan with DBW model converted there engine to non-DBW one for the exact reason.

Cruise control can be ignored but if you want, there are additional cost and labour involved.

You need the Control device box in order to control the VVIS. Otherwise, you will loose huge amount of torque in the low/mid rpm range.
VVIS will be in Open position if you don't have the chamber control solenoid. By default, it is in open position by the return spring force.
EGR control is also inside there.

You will need to simulate JIS spec VSS (Vehicle Speed Sensor) signal in order to engage VTEC.
Otherwise, you won’t get VTEC and if my memory is correct, I think you will get fuel cut at 7,000rpm.
This is the same if you let the ECU go into failsafe mode. It will cut at 7,000rpm.

Obviously, it’s DBW so you will need to convert the TH pedal angle into voltage. Not a problem if you get the OEM TH pedal box under the bonnet for ease of angle-voltage mapping.


If you are thinking of any modifications in the future or if you don’t already have above parts, then as drmikey mentioned, aftermarket full standalone ECU is more cost effective.

There is no immobiliser chip inside the ECU unless you have Oct/03 onwards ECU for JDM.
For UK spec ECU, the introduction of immobiliser for UK NSX was in 97 the earliest so if you have 96 ECU, there is no chip inside.
Even this can be disabled if you know what to do.


I love challenge so I like your idea but the biggest question is, how are you going to test the car as a package from the safety and endurance point of view?
There are many design limit spec when developing a new car at any car manufactures and NSX was the same.
For example, you mentioned the driveshaft and if you change the spec, layout, material, etc, you need to consider the changes in the reverse torque. Under the extreme condition, you want the driveshaft to break and not the internal gbox parts such as the gear teeth, etc.
You have CL in the middle before the torque reaches the crank shaft but again, you need the consideration.
Please remember that our crank shaft is not symmetrical. There is 30deg offset at the crank pin so you need careful consideration for the stress analysis.
This is the reason why you must use the SST to lock the crank pulley when loosening the pulley bolt and never lock the flywheel side like some people do on other models. It will permanently kink the crank shaft if the pulley bolt was heavily seized and still, you won't see any CEL.

If you change the mounting layout/angle of the engine, you will at least need to study the baffle design that you will find at the bottom of your existing crank case.
OEM oil pump is pushing out the oil at 68L at 6,000rpm and you only have about 5L capacity in the sump.
Therefore, it is super important to let the oil return to the sump close to the entrance of the strainer as quickly as possible otherwise you are going to cause starvation.
Without the dyno facility that can tilt the engine in different angle, it's hard to test and gather the data.

Resonance frequency, firewall/bulkhead design in case of accident, mount strength/frequency, brake spec, etc, etc.
If you think the car as a total package, there are so many things to be considered and tested before you can safely run it on the street unless you are using it as a kit car.

Again, the key is to have clear target/goal on what you want to achieve.
Good luck with the challenge.

Kaz

[NSXGB]

Phew, that saved me a lot of typing ↑ :)

[havoc]

:D

I was waiting for your detailed response Simon...surprised Kaz beat you to it! ;)

[goldtop]

Wow! Kaz, thanks very much for providing so much detail and good advice. For sure it seems like the non-DBW conversion would be the best approach, if I keep it all-Honda. I bought the whole NSX engine+ECU+ancillaries from a forum buddy, so I should have everything to go into the Stratos. This weekend I will try to educate myself on which box is which.

> simulate JIS spec VSS (Vehicle Speed Sensor)

Where is this sensor in an NSX - on the gearbox, speedo, etc? An NSX engine with no VTEC would be no fun.

Dudley at Talon (Hawk's build partner) is the guy who had - by pure coincidence - heard about a Japanese Stratos replica owner who has put an NSX engine into his car. He's going there in a few weeks and may get some more information.

I hear what you say about the extra issues - oil starvation, reverse torque, etc. All needs to be investigated. It would be good if I can mantain the C30A engine angle/etc. Not sure if it's possible with the 90-degree V...

[mjames75]

I'm happy to donate my Honda Beat-Do you think we could find a way to fit the engine??!:)

[britlude]

in my experience, if there's enough will, ability, and money, anything can be made to fit anything!!!! (try to use the first 2, it saves on the third!)

the usual problem i find is the 'somewhere' to do such things!

[goldtop]

Will - check.
Ability - B*GG*R!
Money... er, where can I buy some ability? Cheap.

[Kaz-kzukNA1]

....................
> simulate JIS spec VSS (Vehicle Speed Sensor)

Where is this sensor in an NSX - on the gearbox, speedo, etc? An NSX engine with no VTEC would be no fun.
....................

https://lh3.googleusercontent.com/-gPoY6sh_O2s/U0vDCZLWn3I/AAAAAAAAP8Q/D2ceqDyc4-s/s640/IMG_0160-001.jpg
On the Gbox under the rear bank VTEC Spool valve.
Behind the silver metal shield.



https://lh4.googleusercontent.com/-_agKWReYWVo/U0vDBRwP6SI/AAAAAAAAP8I/SAc30bAL18E/s640/IMG_0162.JPG
It looks like this.
On the very early model, instead of the connector, you will see the fly lead coming out of the sensor.

For the signal, you just need anything above 5kph + rpm threshold + Coolant temperature threshold for the VTEC conditions.

If your base chassis has electrical VSS, then please convert the signal to meet the following JIS spec.
This is the same for any Japanese car manufactures.
I wrote this long time ago for NSX Prime post.

++++++++++++++++++++++++++++++++++++++++++++++++++ ++++++++++++++++++++++++
The distance covered per tyre rotation depends on tyre size and even with the same tyre spec (such as 245/40/17), the actual tyre diameter differs from one manufacture to another.

Therefore, you don’t calibrate the speedo against the tyre size.

In fact, in order to eliminate the variation, the VSS pulse is defined in the JIS.


For 4 wheels car, the VSS must be at 637rpm at 60kph.
The number of pulse generated by 1 rotation of VSS must be 4, 8, 16, 20 or 25.


Honda uses 4 pulses per VSS rotation. Please note that this is NOT per tyre rotation because tyre size will change the number of pulse generated.


JIS defines that the input signal frequency to the speedo must meet the following equation.

H[Hz] = V[kph] x 4[pulse per vss rotation] x 637[rpm] / 60[sec] / 60[kph]


So, at 60kph, the VSS square wave has to be at 42.47Hz and this is what you need to use for calibrating the speedo because this frequency is the same regardless of the tyre size or the car models.


As mentioned above, JIS definition is based on VSS rotation and not per tyre rotation.

Therefore, the number of pulse generated per tyre rotation will depend on the tyre size.

Presuming that you have 245/40/17 tyre at the rear, the circumference is 1972.3mm depending on the manufacture.

Therefore, at 60kph with this tyre size, it is at 8.45 rotation per second.

At 60kph, VSS is at 42.47 pulses per second [Hz].

So, 42.47[pulse per second] / 8.45[rotaion per second] = 5.03

Therefore, you will see about 5 VSS pulses per TYRE rotation for this size.

Kaz

[AR]

http://www.acura-legend.com/vbulletin/f2/first-update-legend-sx-124851/

Quite a story and quite a car, a true labour of love!

[Procar Specials]

NSX engine in S2000

http://www.hondaboard.de/wcf/images/photos/photo-11832-66227fac.jpg

[marvalge22]

Get the full OBD2 engine with wiring, ecu and the pedal as it is DBW and you will be good to go.....or get a replacement throttlebody and a full AEM ecu to get rid of the DBW. If you get a OBD1 engine then you will have the problem with the interior wiring as most of the vacume valves and sensor are connected to that and scatterd around the engine bay. On the OBD2 engine most vac. valves and the map sensors are on the engine itself. I know this as i am at mid build with my swap. Have a OBD1 engine + got the wiringharnes from a legend at first but remaking that to work with the accord was a nightmare .... in the end i swaped most part off of my J30a1 engine + repinned the accord V6 harness to work with the C30a3 engine.... so in a way it is now a OBD1/2 hybrid. Was much easyer and and looks clean. Also got a conversion adapter from OBD2 harnes to OBD1 for the ecu. The OBD2 wiring is so far the best as it connect to the ecu and is not tangle with the interior harness like on the OBD1 variant. Hope to finish be project by the end of this year. Waiting on custom engine mounts so i can weld new mount point on the frame. 12153...... and yes it will be FWD on my project. Need it to be road legal.