wantboost

iTrader: (2)

A local friend of mine has expressed a desire to turbocharge his 2014 K24 Honda Accord. The only catch is it has a CVT transmission... He does tinting, vinyl wraps, and other basic vehicle modifications so he at least knows what's involved with turbocharging and as his car is basically a rolling advertisement and his "company" car that drives the most he wants it to be a bit more fun to drive.

He said he wants a solid 400whp. I think we all know that the K24 is very capable of that in 100% stock form on 93 octane with a proper tune. Obviously though the CVT trans is the Achilles heel.

Now while I'm not very familiar with CVT transmissions I do know that by design they are limited in the amount of torque they can safely handle and they also absorb much more power through parasitic loss than your typical automatic. So my concern, which I told him upfront, is that forced induction would probably be a wash due to basically guaranteeing that the transmission grenades quite rapidly.

I also envision dyno tuning and street tuning to be quite difficult since the CVT transmission tries to keep engine RPM within a certain range and since there isn't really a way to force it into a fixed gear ratio (as far as I know) to take the engine through its RPM range. I have seen a few turbo CVT vq35de nissans that were properly tuned but I can't find any specifics on what was involved. My friend did express a possible interest in converting the car to a 6spd manual but is quite involved with the new cars so I'm not sure how feasible that sounds.

Any opinions? I feel I already know the answer, at least with trying to produce 400hp. Would a lower power goal be possible? Say like that of your typical JRSC or Rotrex kit? While not 400hp I feel that a mild power gain from a supercharger would still give him most of the torque/quickness and fun he is looking for, possibly even more fun if using a JRSC kit since he would basically have instant torque on tap.

TIA

civic-steve-94

Explosion..... I am a mechanic by trade and see soooo many Honda Odysseys and accords with over heated/ destroyed CVT transmissions. Those were the older generations though 08 is the newest one I have seen. I don't know if its the area I live in(which is the middle of the sonoran desert) or what but high heat and CVTs don't mix well. If your friend does decide to go ahead with this project I recommend a vary large external cooler.

wantboost

iTrader: (2)

See I was expecting a large efficient trans cooler and a performance synthetic trans fluid to be mandatory.

I just think the design won't handle any sizable torque increase, at least not the torque at 400hp. I don't see why a basic JRSC kit would be out of the question though

civic-steve-94

I agree Honda tends to over engineer the oem equipment, as long as it stays cool. It would definitely be interesting to see how the vehicle would respond to boost with the CVT transmission. If your friend goes through I think a thread would be warranted for future researchers.

wantboost

iTrader: (2)

You can't really overbuild a CVT transmission. Even the most well engineered unit can only withstand a fraction of the torque production a standard automatic could support. Most aren't rated for more than 175-200lbft depending on construction.

I'm just trying to gauge if even the modest torque increase from your typical JRSC kit would cause an eventual failure.

He's a responsible mature adult and it's a 4dr Accord that's vinyl wrapped and currently lowered on a set of really nice and tasteful 20" Niche wheels although he's about to move to a 19" set. He won't be bearing on the car, drag racing, or doing burnouts and other crap. He just wants a little bit more "pep" out of the car so it's more enjoyable to drive. Given the size and weight of the car 400hp is what he came to for it to perform like he wants. Granted I don't think the transmission is capable of that unless he does a 6spd swap first.

I can't recall what a "standard" boost pressure non intercooler JRSC produces on a K24. I know the Rotrex units make good power but being centrifugal they would lack the low end of a roots blower but have more top end which in the end I don't think he would enjoy as much, at least not during a typical daily commute of stop and go.

Kevinio

The torque on the CVT is one issue, but an other issue is how to program the CVT. I think you have to use EOBD tuning, which is a hell of a job with an automatic transmission (I really hate EOBD tuning). I don't know if there's a stand alone EMS which can control a CVT?

LightningTeg

Why did he get a CVT Accord if he wanted more "pep" lol. Did he not test drive it?

wantboost

iTrader: (2)

There's no way to access and reprogram the module or part of the ECM that controls the transmission. There's also not a lot to be done as far as reprogramming because a CVT trans only works one way. You might be able to change the engine rpm it holds, the rate at which it changes ratios, or the starting ratio, etc but none of that would change the amount of torque it can withstand.

SalvadorSZ

Do CVTs have clutch packs like standard autos? because the tq of a roots charger would burn those in a minute

wantboost

iTrader: (2)

They have a clutch pack that's used to engage the transmission from a dead stop and a clutch pack that engages forward rotation but that's it. The forward clutch pack stays locked up when the car is in drive. As soon as the vehicle starts moving the start clutch locks up.

They use a metal chain that forms a circular belt that sits between two shafts, both of which have conical pulleys that widen or narrow as needed to change the forward gear ratio seamlessly.

Honda CVT


CVT Components


How they change ratios


So you can see why the design is torque limited. There's nothing that indexes the metal chain belt to the pulleys, no teeth or grooves. So if the torque input increases too much they simply slip until something fails. Also most CVTs "push" the belt as opposed to pulling (one Audi CVT does pull the belt) which also lowers torque capacity.

Now there are a few designs that can handle higher torque loads but the majority of those are RWD based. All FWD CVTs tend to use the metal chain

LightningTeg

Yeah a stout CVT that works reliably would be a game changer for IC engines.

wantboost

iTrader: (2)

Apparently Audis pull type is fairly stout for a chain style CVT. IIRC it is an option on the turbo engines.

One company uses a hypoid style that has no belts and can't slip and apparently can withstand all sorts of abuse. I can't remember what brand though and I don't recall if it was a FWD option, I know they are used in that brands RWD platforms.

I'm fairly certain the torque from a 400whp K24 would murder a CVT quite rapidly, especially due to the high amount of power they sap from the crankshaft so it might require well near or over 500 crank hp to see 400whp.

I wonder if I could convince him to run a supercharger. I find it hard to believe that a basic JRSC setup, even one with slightly elevated boost pressure and an intercooler, would generate enough torque to damage the trans. Remember that it's simply a DD, a family car, and his company car/rolling business card so there will be no burnouts, neutral drops, or **** like that. It will be responsibly driven by an adult because with his company info on the car it would make for bad business to drive like a jackass. Now he will occasionally drive the car in a "spirited" manor. Maybe a few highway pulls here and there, trips to mountain roads and meets, etc but nothing that would be considered acting like a hoonigan.

Flr Power

I sure hate CVT, makes the car boring to drive and it is a weak tranny.

But you should tell your buddy to go for the new Acura ILX 8-Speed DCT (Dual-Clutch Transmission).
2016 Acura ILX | Specifications | Acura.com

Now, that's a transmission for the future. But when you raise the stock engine power to higher level, it is fairly easy to burn it or break it.

wantboost

iTrader: (2)

Yea while researching I came upon a video of a turbo vq35de Altima with a cvt trans.

It seemed boring as hell to drive... Push gas pedal, reach "optimum" rpm point, blah. Plus you could hear the cvt flipping out. As soon as the wastegate opene you'd hear what sounded like a dying automatic changing gears followed by random sounds including the blow off valve, wastegate chatter, and compressor surge. This was under WOT too. Plus it seemed like the car didn't really pull or accelerate hard once it made full boost, it just kind of chugged along in an underwhelming manner as the gear ratio constantly changed. None of the typical violent acceleration of a traditional multi speed transmission with defined gear ratios. Watching the dyno pulls made the cvt seem even more retarded.

I would describe it like watching a **** that stops right before the money shot. All that build up and anticipation only to be completely let down and disappointed lol.

I guess with a cvt trans it makes sense to size turbocharger as though it were a constant rpm application because 99% of the time the trans is going to keep engine rpm within a narrow "optimal" range.

ek9+eg6=me

ek9+eg6=me

Y'all keep talking about the CVT trans problem what about high pressure fuel pump on them and special made high pressure injectors, or trans valve body issue , or piston update, I work on these everyday your best bet is to leave it alone

wantboost

iTrader: (2)

You don't touch the direct injection system. You add supplemental port injectors. Granted modifying direct injection systems isn't hard. BMW, VW, and Mazda guys have been doing it for years. HPFP upgrades, DI injector upgrades, etc. It's just getting the software side to support those changes.

I saw him Friday and basically said you're better off leaving it alone. He's waiting to see what availability is going to be like on the 2016 Sport 6spd models.

bsg_75

Sorry to bug into your conversation, but I have an i-4 9th gen coupe with the CVT as well and have been searching for a turbo/supercharger forever, but I realize I might be crazy to want that. I should've got the V6 three years ago, but I was in a different mindset. I'm looking for something modest. Still have my fingers crossed.

Side note: Do you know of any kits that would actually work on the V6 9th gen auto? I *might* trade mine in for a V6 but I'm still unsure.

I did a ktune, exhaust upgrade, RV6 downpipe, and a short ram intake and it's much better, but I want more!

X2BOARD

I am not sure if the CVT design used by Honda has changed since the JDM EK civics, but a friend of mine ran a turbo 00 EK sohc D15b CVT setup, turbocharged for some time, even winning its class in an autocross championship (likely only about 200whp) but the key they claim was religious maintenance with fluid and filter changes. I'm sure an oil cooler couldn't hurt. The car in question is still running as a daily driver without boost, second owner.

but as a daily with a family... i wouldn't spend on the risk...

Tony the Tiger

The CVT transmissions are an item that is very prone to wear and tear so it's like a countdown the first day you own the car. It's not that they are extremely weak, so they rarely just explode due to power, because most of the Nissan ones do hold up with some power and I know a few guys putting some nitrous through them.

The only concern would be a very short service life after being boosted. They slip when being over powered, so my guess it would fail very shortly if your buddy decides to boost the car on a daily basis. However, it he's going to drive normally on his daily commute and only save the car for a few good pulls, I think it will last for a while IMO.

Although with 400WHP, it's a bit much to ask for. Even the regular Honda automatics have trouble with that power, and the CVT can only be regarded as having less holding capability.