Smart Car of America Forum banner

Smart HarD Tuning GR may finally address US model Smarts

765 Views 29 Replies 5 Participants Last post by  twcom

This may be what we have asked Smart HarD Tuning of the UK for a while now, some power upgrade for the non Turbo 451 models of the US.

Now reading through most of us looking for this type of upgrade have many items covered already. Ahh then the bigger "throttle bigger".......... Hmmmmm? 馃馃弫?
1 - 20 of 30 Posts
Never heard of the "throttle bigger" before but I was actually working on adding a larger TB to a custom intake manifold myself. Didn't know anyone else had already done it.

I notice the picture shows new injectors and some wiring harnesses as well yet they're not mentioned in the listing. Also, no pricing.

The dyno looks nice but I would've loved to see the "before" curve to get an idea of what the car registered as stock. While 89hp sounds great you really need to see the original pulls on the same Dyno to get an idea of the actual performance delta.

This is only bolstering my resolve in modifying the factory intake manifold for a larger TB. Plenty of cheap Bosch units online that are plug and play. Just need to verify they'll bolt up and the intake opening isn't a bottle neck.

P.s. don't mean to highjack your thread but I went ahead and ordered a spare intake manifold and a few throttle bodies of various sizes for testing and fitment. I'll absolutely do before and after Dyno runs to see if there's anything to be gained from this mod.
See less See more
  • Like
Reactions: 1
2
Never heard of the "throttle bigger" before but I was actually working on adding a larger TB to a custom intake manifold myself. Didn't know anyone else had already done it.

I notice the picture shows new injectors and some wiring harnesses as well yet they're not mentioned in the listing. Also, no pricing.

The dyno looks nice but I would've loved to see the "before" curve to get an idea of what the car registered as stock. While 89hp sounds great you really need to see the original pulls on the same Dyno to get an idea of the actual performance delta.

This is only bolstering my resolve in modifying the factory intake manifold for a larger TB. Plenty of cheap Bosch units online that are plug and play. Just need to verify they'll bolt up and the intake opening isn't a bottle neck.

P.s. don't mean to highjack your thread but I went ahead and ordered a spare intake manifold and a few throttle bodies of various sizes for testing and fitment. I'll absolutely do before and after Dyno runs to see if there's anything to be gained from this mod.
So as Smart HarD Tuning GR is in Greece the translation would be Bigger Throttle.
I have loosely glanced at a few articles on individuals installing larger throttle bodies on Smart cars so I can imagine it not too unlike the days past when carburetors sizes where swapped around. I have not read enough to have a reasonable input about it Smart throttle body swaps.

So with that being said... Note I have been following Smart HarD Tuning and their work with the Turbo Smart engine performance for quite some time. I have had many messenger chats with Them on ideas and help with the USA non turbo Smart versions. I am very pleased to see that they may now provide some Non Turbo 451 smart options the USA 451 Smarts may benefit from.

Disclaimer
** Note Please that I am not reckless with my post that they could lead to some sort of scam or financial loss to someone. I have never made a financial transaction with Smart HarD Tuning GR until today 4/15/2023. I will report on my purchase experience. So feel free to wait until I receive my order and report on it **

I did have a face book friend in Georgia USA .. ( now Resting In Peace ) who built his Smart Turbo engine with help and parts from Smart Hard Tuning GR.

So I am leaning on a little more than faith going in to this first transaction.

I am not debate prices that will be quoted as while money always matters to me, I started my conversations with Smart HarD Tunning GR by asking if they could get my 451 here in the USA to 110 HP. Their focus and development was strictly focused on the EU Turbo Smarts. Fast Forward nearly two years and there is a Stage 1 package for Non Turbo 451's that would support 90 HP and a Stage 2 package that would support 110 HP. Prices will be what the are and as tight fisted as I am, I will either pay the quoted price or not.

So here is where I Start this stage 1 upgrade attempt.

Forge Silicone Hose..... I have one installed
KnN filter in stock air box..... I have one installed
Performance exhaust...... I have one installed
SHT ignition coils...... ordered 4/15/2023
NKG Spark Plugs...... ordered 4/15/2023
Bigger Bosch Injectors......
Bigger Throttle Body........
ECU Remap........

That is the extent of the Stage 1 performance upgrade.
We will see how much I can get done.
Motor vehicle Automotive exterior Vehicle Gas Auto part


Wheel Vehicle Car Tire Vehicle registration plate
See less See more
Yeah. I'd feel pretty confident saying that a larger TB and injectors would go well with the standard bench flashes being sold by everyone.

I looked over their site and the products i'm most interested in are the lightened flywheel and crank pulley. The flywheel drops about 1.5lbs and the crank pulley weight is cut by 85%. I bet that might make the smart rev like a sport bike. However it might also negatively impact the daily drivability with the automated clutch control. Only testing will tell.
  • Helpful
Reactions: 1
I will follow this closely .
  • Like
Reactions: 1
I thought in waiting that "it would be nice to have that valve cover Chrome or painted while it is off."
  • Like
Reactions: 1
I thought in waiting is that "it would be nice to have that valve cover Chrome or painted while it is off."
I was thinking the same thing.
  • Like
Reactions: 1
2
Package delivered 4/20/2023 from Smart Hard Tuning through DHL express shipping. It was very well packaged.

Packing materials Staple food Font Packaging and labeling Cuisine


So I have a set of SHT Ignition coils with connection wires, and a set of NKG spark plugs.

Font Fashion accessory Brand Box Publication


There was also a nice supply Smart Hard Tuning decals.

I will ask if the new spark plugs should be in stalled now or after the remain items including the tune are installed. But Know that Smart Hard Tuning advertised themselves as a a company that supplies products for Smart cars. I made an Order and quickly received the product I ordered without issue.
I do not anticipate installing the new coils until next weekend at the earliest. The plugs. bigger injectors. bigger throttle body and the ecu map my need to be an all at the same time install. I just Drove My car on a 1,440 mile road trip and it performed so well I am in no hurry tamper with it so I will work on buying the bigger Throttle body and the bigger injectors. the ECU tune will be an issue as I would want my ecu tuned in the car rather than uninstalled shipped out then reinstalled after it is shipped back to me. Another point is that my car in 4th gear quickly get the car to its 92 MPH speed limiter so to put on all these goodies to still hit the same 92 mph speed limiter seems a bit wasteful.
But Smart Hard Tuning thumbs up .
See less See more
  • Like
Reactions: 1
I'm very curious about the size of the TB they sell. I'm hoping to do my own tests soon so maybe we could compare notes.

What was the model of plug they sent you? The owner refused to tell me what plugs they still because he didn't want me buying my own locally for less.

I am also interested in actual tuning options for our cars and since I'm planning similar mods we should put our heads together and see if we can't come to a solution faster.

Good luck with everything.
鈥92 mph in 4th gear鈥
鈥hat was the rpm???

jetfuel鈥??
On a flat surface between 4700 to 5000, the steepest hill on the way back took it up to 5700 at the highest. Water temp never was higher than 193 degrees F. It was very happy to be in the higher revs. The 225/50 15 rear tire height has it in a very good place.
I'm very curious about the size of the TB they sell. I'm hoping to do my own tests soon so maybe we could compare notes.

What was the model of plug they sent you? The owner refused to tell me what plugs they still because he didn't want me buying my own locally for less.

I am also interested in actual tuning options for our cars and since I'm planning similar mods we should put our heads together and see if we can't come to a solution faster.

Good luck with everything.
At this point I am going to protect his plug choice especially since I have not install it as yet. The throttle body may be my next purchase. I believe I will collect every thing this summer and in the fall actually install the upgrade. Primarily because my car is running optimally right now and seconderaly A TCU tune is what I need most right now. To throw more energy at my first and second gear shifts would be abusive in my opinion. For now just know with "Smart Hard Tuning" I ordered something and recieved what I ordered quickly without issue.
I don't understand this secrecy around spark plug choices. I was just curious to see if he changed the length of temp range.

I don't think you're going to see any difference (positive difference) from swapping out coils and plugs unless your current units are old or out of spec. I feel pretty confident in the factory engineers choice of plug, unless there's some known issue that I just haven't heard of yet.
  • Like
Reactions: 1
I don't understand this secrecy around spark plug choices. I was just curious to see if he changed the length of temp range.

I don't think you're going to see any difference (positive difference) from swapping out coils and plugs unless your current units are old or out of spec. I feel pretty confident in the factory engineers choice of plug, unless there's some known issue that I just haven't heard of yet.
Well KFC guards their recipe and what is the special sauce on that burger . Lol. As far as plugs go my original plugs were Denso,. I changed to NKG iridium laser plugs. So what the manufacturer installed and why are always a decent conversation. I just do not know if I will put in the new plugs until I install the throttle body, injectors, and have the car tuned.
  • Like
Reactions: 1
It appears stage one is no longer needing the bigger injectors so I will be ordering the throttle body soon. NYC weekend was a rain out so no ignition coil install yet. Check out Stage 2.
  • Like
Reactions: 1
It appears stage one is no longer needing the bigger injectors so I will be ordering the throttle body soon. NYC weekend was a rain out so no ignition coil install yet. Check out Stage 2.
Have you measured the size of the opening in the manifold where the TB bolts to? If it is not as big, or bigger, than the TB you are ordering then you not accomplish anything. In fact the incoming air will hit that lip and setup a turbulence that will in-turn block some incoming air.
You can use a Dremel to enlarge the manifold, just make sure to stick a vacuum cleaner hose in and around your work and put a rag back into the opening far enuff back so as not to catch it with your cutter.
Just saying.
  • Like
  • Helpful
Reactions: 2
Have you measured the size of the opening in the manifold where the TB bolts to? If it is not as big, or bigger, than the TB you are ordering then you not accomplish anything. In fact the incoming air will hit that lip and setup a turbulence that will in-turn block some incoming air.
You can use a Dremel to enlarge the manifold, just make sure to stick a vacuum cleaner hose in and around your work and put a rag back into the opening far enuff back so as not to catch it with your cutter.
Just saying.
I ordered a spare intake manifold and TB. It just arrived today. I'm going to take detailed measurements and cross it with Bosch inventory to see what units fit the mounting points and how much room there is in the i.m. to hog out the opening.

Maybe there's room for improvement, maybe not but I'll document everything for prosperity. This is the only proper way to know for sure
Curiosity got the better of me and I went ahead and cracked open the manifold and TB to see how much room there was to grow
.

The answer is "0".

There is NO reason to add a larger TB without a custom intake manifold. The stock manifold will not allow a larger TB to be fitted. The aperture in the manifold is as large as it can be and the TB is the exact same size as the manifold opening.

Anyone trying to sell you a larger TB should be seriously questioned. A larger inlet means NOTHING if the manifold is the choke point.

Just fyi, this cost me $140 to share this info with you guys. Hopefully it'll save more of you money in the future.
  • Like
  • Helpful
Reactions: 2
Have you measured the size of the opening in the manifold where the TB bolts to? If it is not as big, or bigger, than the TB you are ordering then you not accomplish anything. In fact the incoming air will hit that lip and setup a turbulence that will in-turn block some incoming air.
You can use a Dremel to enlarge the manifold, just make sure to stick a vacuum cleaner hose in and around your work and put a rag back into the opening far enuff back so as not to catch it with your cutter.
Just saying.
I accept what you are pointing out. But I intend to bolt the new throttle body on and see what happens. I will read more on throttle bodies to compare to my memory of carburetors as certain size carbs could interchange on the same intake manifolds. There would come a point where changing the intake manifold would come into play. About a month away for me to order it.
I accept what you are pointing out. But I intend to bolt the new throttle body on and see what happens. I will read more on throttle bodies to compare to my memory of carburetors as certain size carbs could interchange on the same intake manifolds. There would come a point where changing the intake manifold would come into play. About a month away for me to order it.
Make sure you read what M365 found out, you may want to save your money for something that has a chance of improving performance and not subtracting from what you have. A good trick to check if you have a intake (TB) bottleneck is to connect a vacuum gauge to the intake manifold, accelerate in gear to 5K+ RPM, and see if the vacuum gauge reads about 1/2" of vacuum or less (it should take two people to make sure you are watching the road). If it does not read over 1/2" then the intake is proving all the air the engine can use. In a naturally aspirated (NA) engine it take a reduction in atmospheric to pull more air from the TB. Try it with and w/o the air cleaner hooked up. If your air cleaner setup is not causing a restriction then the 2 readings will be very close.

Just some friendly advise...
  • Like
  • Helpful
Reactions: 3
1 - 20 of 30 Posts
Top