turbo-ing the NSX?

710

710

Experienced Member
Joined
19 December 2004
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937
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Belgium
Can some of you guys please give me some links to turbo charging my NSX relating to the below info? I have done a search, but it comes up with way too much general info.

I want to keep the cost down. This is not a race car, it’s my daily car (1991 3.0 stock). I would like to keep the engine safe and reliable. I want low down-time too.

I have decided to try to get around 400hp. I have looked at supercharging but for several reasons have decided on turbo-ing. This is based on a couple of assumptions (feel free to correct me, please):
Assumptions
-no lag because engine stays the same as now, stock compression etc..
-$1000 for headers, gain 15hp. Waste of money, better turbo and keep the cast iron exhaust manifolds. Get more than +15hp.
-0.3 bar is not much more strain on engine especially if the impellers are big, so less heat is generated / more volume
0.3 bar (4.2psi) will give about 100hp increase in power?
Change the VTEC point to about 4000rpm?
I assume the stock manifold and throttle body is sealed enough to suffice?
Would the stock clutch take 400hp. I am very soft on clutches, they last a long time with me. But does the stock one clamp hard enough? Anyway, I could upgrade…

I would:
-leave engine the same, change the ECU (I have experience with ECUs and mapping)
-2 small turbos something like the garett T25 (I have a few new T3 lying around and would like to use them in someway. I could have them changed). Each has a waste gate. Actuator type?
-the T3s that I have are water cooled, but I would not need to use that?
-2 turbos is a more elegant installation that one turbo.
-2 or 1 water/air intercoolers, I have found someone to make them cheaply, they will be of the contra-flow type. (I already have the water pump and front radiator lying around)
-stock manifold and throttle body.
-may have to change the injectors?
-may have to change the fuel pump?
-will have to change the fuel pressure regulator, needs a vacuum line
-one adjustable blow off valve before the throttle body (already have)
- a electrical oil scavenge pump to get the oil back into the sump (already have). I can easily fabricate the rest. Where do I drill a hole to return the oil to the sump. I don’t want to take the sump off, is there an existing hole somewhere?
-I would take the oil pressure off the oil pressure sensor or something like that. Would it flow enough for the turbos?

Lag is my biggest concern, but if there is no boost, then won’t the throttle response be the same as my car now? Maybe a little less because of the restriction in the exhaust manifolds (the turbos are sitting there), but essentially the same. True or not?

Thanks
Peter
 
headers make a huge difference on a 91, do that mod first wtih an exhaust. you will notice a change.
There is "NO CHEAPO ROUTE" to turboing an NSX. You will spend more money than you think one way or another. Sure you can get a turbo on an NSX for under $5000, but it wont be reliable and it wont hit 400 at the wheels. To get that # you will have to go with a standalone system.
For cheap, reliable,fast power, do I/H/E and a 75 shot. You wont be disappointed. I ran nitrous for years with no problems. Good Luck
BTW many people are getting around 400hp with the Comptech SC and AEM. Seems to be a pretty solid alternative.:cool:
 
peter. you are going to get FLAMED for this post but you are pretty close on your numbers (except the 400 hp w/ .3 bar and small turbos) you even metioned big props.. ??..

if you already have 1/2 the stuff like you have said i dont see why adding fuel to the increase in air will not result something positive.
 
There is NO low end turbo setup for NSX. Maybe for civic but not for NSX. I was where you are 2 years ago, and after going the cheap route I spend $15,000 on my single turbo.

At the end of the day you will spend more then you think and when you think you got it just right something goes wrong. OEM pistons are not too good for turbo FI the ringlands on pistons will crack if not tunned right. Supercharger is easier on them. But I think you are on the good path with parts. New clutch and headers are good start. Turbo generates more TQ then supercharger and oem clamping pressure will not hold oem clutch. You should be fine with those twin turbos. Cut in to the oil pan as high as you can over oil line. I would go with RC550s, and new fuel pump with new FPR, water/intercooler, And don't forget to get Wideband Controller and stay in 12.5a/f It is all doable if you have the time for it.

Good luck
Dave
 
If you don't have at least 12k dedicated to get this turbo project rolling... DON'T ATTEMPT.
Like most here will tell you, it can't be done cheap.
 
710 said:
?
Lag is my biggest concern, but if there is no boost, then won’t the throttle response be the same as my car now? Maybe a little less because of the restriction in the exhaust manifolds (the turbos are sitting there), but essentially the same. True or not?
Click to expand...
Not sure if you have driven turbo car before, lag is a misconception, obviously there will be huge lag on big turbos that make 600~1000rwhp. For the 400rwhp~500rwhp level, small turbo will do the job with minimal lag to NA V8 like powerband. Here is a dyno sheet of a turbo nsx, it makes as much low end just as stock NSX:
http://www.nsxprime.com/forums/attachment.php?attachmentid=21848&d=1130863903

People who never driven one, always say there is huge lag on turbo charged cars. Even some nsx owners have told me about that, imho many nsx owners are very biased when comparing NSX to any other cars.

In reality not every turbo charged cars are equipped with large turbos. There are small turbos that makes 250rwhp~300rwhp from as low as 3500rpm on a 3.0L motor, and it will reach maximum boost way faster than any superchargers.

If you keep the stock compression ratio, I doubt you will lose any low end torque.
 
The only off the shelf twin turbo kit that I have found is the Cartech Twin turbo kit. It uses two T28 internally wastegated turbos. Comes with muffler,BOV, intercoolers, and AEM EMS for obd1 applications. I think the website is www.cartech.com. The kit sells for $7995.00 with EMS and is capable of at or above 400hp at the wheels with stock internals if tuned properly. I talked to a shop in CA that did an install and they are the ones that told me that the car dynoed at over 400 at the wheels, however, they said the install for the 3.0 was not direct bolt on a few parts had to be fabricated because the kit was designed around the 3.2 liter exhaust system. But still seems the best route to go if you want the twin turbo setup.
 
bpiddy said:
The only off the shelf twin turbo kit that I have found is the Cartech Twin turbo kit. It uses two T28 internally wastegated turbos. Comes with muffler,BOV, intercoolers, and AEM EMS for obd1 applications. I think the website is www.cartech.com. The kit sells for $7995.00 with EMS and is capable of at or above 400hp at the wheels with stock internals if tuned properly. I talked to a shop in CA that did an install and they are the ones that told me that the car dynoed at over 400 at the wheels, however, they said the install for the 3.0 was not direct bolt on a few parts had to be fabricated because the kit was designed around the 3.2 liter exhaust system. But still seems the best route to go if you want the twin turbo setup.
Click to expand...
The Cartech kit is FAR from an off the shelf kit, it doesnt even come with bolts to hold the parts together and there is alot of extra fab and parts needed. The piping welds leave lots of room for improvement too. The only installation instructions that are available are a group of 10 outdated pics of the original kit on a 3.2ltr car. You can easily spend $10000 to have the Cartech installed correctly.:frown: Ask me how I know.
 
I have alway felt the NSX, a cutting edge car, should use turbocharging, a more advanced forced induction system, than supercharging. I would use the cartech system over a self made system. Or at least get their fuel management system and over enrich it untill you can safely get it to operate in a safe zone. If you've never built a turbo system, and I have not, the NSX may not be the place to start.
 
710, you say better turbo and keep the cast iron manifolds. I believe you will need new "turbo" specific manifolds or manifold flanged for whatever turbo/s you plan on using , t3/t4 for example.
 
Look at spending $25,000.00 + to do it right....I have seen some set ups in the $50k plus range.
 
Whenever i talk about turboing to racers they always say they'd rather have an N/A 300bhp car to a 400bhp turbo car. Besides, performance Honda's are all about N/A baby!

Get throttle bodies and revel in that induction snarl!

Jenvey could probably do you a custom job, with some nice carbon fibre trumpets. http://www.jenvey.co.uk/

-Rob
 
Wow, thanks for the info and opinions. I really appreciate it. One of the major reasons I bought the NSX was because of the support on this website.
Your posts are all very helpful. Thanks.

I see and understand all of your points, the NOS, the supercharger, pros and cons etc. and also the “disgrace” of turboing our great little responsive car. I also would not normally turbo the NSX, but the power is not as befits this car. Needs more.

And normally, introducing lag in this car would be very bad, a real disgrace. The car’s response and sound is too nice to ruin. But because I would not be changing the compression ratio, I believe the car would be just as “sharp” with a turbo system as without it. I mean, it has huge turbo lag at the moment, you can wait forever for the lag (because it doesn’t have any turbos on it…). So I’m reasonability sure the response would be almost identical to now because the power at low/no boost would be what it is now.
The induction sound should remain the same too, since I’m not changing the inlet manifold. But we will see (or hear, rather).

The only difference would be more power. Mapping the engine properly should be easy, like it always has been with other cars.

So I feel I would not be “ruining” the car or the way it feels. If that were the case, I wouldn’t do it. I’m not even going to cut the wiring loom, I can still use it if I make an adapter to go between the stock plug and the new ECU. I won’t cut up the exhaust or anything else either.

But it needs more power. And since I drive it daily, a supercharger would introduce generally lower fuel mileage and unreliability (I think). Do you know how much gas costs over here? Ok, you say, buy a Mini. But, no, I drive the NSX everyday to work, rain or shine, 33,000miles a year. And the mileage now is very good, even at the high speed I use it at everyday (100mph for about 30-40 minutes constant). So I don’t want to introduce a 10% fuel drain because of the SC. Anyway, I don’t have a supercharger in stock.

Post #4 about the piston crowns being fragile, that really worries me. Are the pistons fragile? The boost would be about the same as a supercharger kit, do they use the stock pistons? I’m heading over to their site right now… I need to know at how much boost the pistons become a problem.
Also it was mentioned that supercharging is easier on pistons. Can you tell me more, because I don’t get it. If my turboed air is the same pressure and temperature as with superchargered air, how do the pistons know the difference? Is it because the boost from a turbo is lower down the rev range, so the stresses are more. Or is a supercharger boosting lower down the rev range?
Or is it because the guys breaking pistons are still using the stock ECU and the air/gas mixture and ignition timing is all wrong?
The cost I have at the moment is (assuming the pistons are strong enough for moderate boost if mapped correctly):
--Turbos- rebuild mine into hybrids (like the T25 for example): $400x2 =$800
--Machine and construct adapters for mounting the turbos on stock manifolds: myself
--Stock muffler: have
--catalytic converters?? Don’t know yet. Has to get through the yearly inspection, so needs cats. But they can be empty. A special ECU map will get me through the inspection. But maybe I should buy aftermarket CATs…
--Fabricate exhaust pipe from turbos to muffler: myself / have many parts
--Crank trigger disk: Make myself
--ECU including crank sensor and loom: have
--make adapter for stock ECU connector so use most of the stock loom
--Replace water temp sensor and air temp sensor (maybe): $100
--MAP sensor: have
--Intercoolers water/air: $360x2= $720
--front radiator and water pump: have
--Fabricate inlet tract: make myself / have many parts
--Fabricate oil collection: make myself / have many parts
--Oil scavenge pump: have
--few hours on dyno for mapping $400
--bigger injectors: maybe needed
--Bigger fuel pump. Maybe needed

Did I miss anything?

Comes to $2020. plus my work. Plus some extra bits.
That’s a just a little more than the price for headers. And I get way more power.

Judging by some of the last posts, I didn’t make it clear that it needs to be remapped. So throw away the stock ECU, I mean completely change the computer for another one. That’s easy these days, there are many on the market, and I have a couple here already from the rally car.
I can’t accept that people put a SC etc on without changing the computer and mapping completely. THAT would be disgraceful.

Peter

PS: Rob, hey we have to get together some time. I missed you at the Autosport show last week! And I already have a Jenvey setup for the Elan, nice!
 
Last edited:
ediddynsx said:
Look at spending $25,000.00 + to do it right....I have seen some set ups in the $50k plus range.
Click to expand...

Cost is directly tied to the amount of power you are looking to produce. Going the FI route is by far the more economical way to produce power, and in our opinion the most fun way:)
 
robfenn said:
Whenever i talk about turboing to racers they always say they'd rather have an N/A 300bhp car to a 400bhp turbo car. Besides, performance Honda's are all about N/A baby!

Get throttle bodies and revel in that induction snarl!

Jenvey could probably do you a custom job, with some nice carbon fibre trumpets. http://www.jenvey.co.uk/

-Rob
Click to expand...

If you plan on having a dedicated NSX race car or track rat, NA is a good route. If you are primarily a street driver with moderate track use, FI is incredibly addictive. We speak from experience as we have built and driven damn near every power adder for the NSX with the turbo system being far and away the most fun.
 
SNDSOUL said:
Sounds like you have it all figured out…
Click to expand...
Not quite.
I don’t know if the oil port where I will take the oil from will flow enough for 2 or even 1 turbo.
And can the oil pump in the engine cope with the loss of oil or can I change the relief spring in the oil pump to make it cope?

So to make it even more complicated, but maybe better, I can separate the oiling of the turbos completely (since I already have separated the scavenging of the oil), by putting an oil pump driven by an electric pump. Then the pump can start 1 second before I turn the engine on and stop 1 minute after I turn the engine off. That way the turbos keep getting oil after the engine is stopped, protecting the turbos. And the engine oil isn’t contaminated by burnt oil from the turbos.
But I don’t know if anyone even makes that type of oil pump. It would have to be pretty strong I guess.
And furthermore, maybe cold thick oil is not good for the bearings in a turbo. Or maybe it is better. I don’t know…
Do any of you guys know where I can look for these points?
Peter
 
I think making the car turbo will in fact sap some power from stock, as opposed to 710's assumptions. The turbos are a huge, giant blockage in the exhaust route, so when they're not yet doing their job of boosting, they're just getting in the way of the engine's exhaust. With properly sized housings and wheels, the wait for boost can be minimized to almost nothing but will never be lag-free and will change the character of the motor when off-boost as well as on.

J
 
Andersons 911 book says to use Jabsco 16360-0003 electric bilge pump motor/impellor for transaxles, should be OK for any lubricant.
Or use 0 weight synthetic oil like the twin turbo RX-7 guys do; keep it simple.
I'd go with a single larger turbo with monster intercooler to keep intake temps down so detonation with high compression pistons less of a factor.
Feel like experimenting ? Reno air racers use up to 50/50 fuel to water injection on their 100+ in/hg engines.
Keep us up to date.
 
710,
It sounds like you're going after a set-up with similarities with mine however I have a built engine.
You will need a water tank and pump for the intercooler. And don't forget all of the plumbing for a watercooled twin turbo. To make yours an "elegant" installation, will take a lot of time and patience, but it can be done. The NSX has limited space for all of the components you will be installing. I also went for an "elegant" installation for my watercooled twin turbo. People are surprised at how "clean" and "OEM" mine looks considering all that it has in it.
If you go with small twins you shouldn't experience much lag.
I don't. I can get boost as soon as 1,800 RPM.
GOOD LUCK!!!
 
stevenlee said:
710,
It sounds like you're going after a set-up with similarities with mine however I have a built engine.
You will need a water tank and pump for the intercooler. And don't forget all of the plumbing for a water cooled twin turbo. To make yours an "elegant" installation, will take a lot of time and patience, but it can be done. The NSX has limited space for all of the components you will be installing. I also went for an "elegant" installation for my water cooled twin turbo. People are surprised at how "clean" and "OEM" mine looks considering all that it has in it.
If you go with small twins you shouldn't experience much lag.
I don't. I can get boost as soon as 1,800 RPM.
GOOD LUCK!!!
Click to expand...
Thanks for the info Steve, The turbos I have can be water cooled. They are from a Cosworth Escort and because of the work they are doing (high power and boost) 1.3 bar etc so they should be cooled.
But for my low boost NSX I didn't know if I should bother with the water cooling of the turbos (saves on pipe spaghetti etc). Because my oil pump will continue to circulate the oil after I stop the engine. Do you think I should also hook up the water cooling?
Do you have any photos of the underneath of your car? I have done some measuring and I think there is just enough room at the front of the engine for a turbo. I even considered getting a second cast iron manifold from the “rear bank of cylinders” and putting it on the front bank. Because it comes out the middle. Do you know if that will fit?
What compression pistons do you have? How much boost?
And most importantly, does it give the car an impressive increase in acceleration? Up to your expectations?
Peter
 

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