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Discussion Starter · #1 ·
Does anyone here have any experience with hybrid turbos on the 4C? Is it worth it? The new version 2 hybrid turbo kit from alfaworks looks like a super sweet kit. GMS claims to make about 330hp on their 3” exhaust, intercooler, intake, and tune. This is about the same hp range marketed for the hybrid kits. GMS said if you add a hybrid turbo to the previously mentioned combo it would only net an extra 10-15hp (that would be a very expensive 10-15hp). More boost to a more efficient exhaust/intercooler/intake seems like it would be a bigger hit. Sorry for getting off track but any hybrid turbo experience would be much appreciated!
 

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Discussion Starter · #3 ·
What make the turbo hybrid?
That’s just what i’ve seen people calling them when the stock turbo is reworked for better performance. Typically a better/larger compressor wheel and enlarged housing. They spool much faster and make a higher peak boost.
 

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Perhaps I was a bit too enthusiastic comparing two extremes here - stock vs. hybrid. On stock turbo, you can get 330 hp out of it, for the dyno to brag, but it's hard to keep that power all that high constantly due to lots of heat generation as you're pushing the turbo outside of it's optimal efficiency chart and therefore causing even more heat. On stock car with an aggressive tune, IAT can easily reach over 60°C and at that temps the ignition is already retarding heavily, robbing you of power and if still not enough, boost will be limited. If you have a free flowing exhaust, good intercooler and good engine mapping with high rpm power focus, so you don't boost too aggressively at low rpm's, then you can expect to be in a range of about 290 - 320 hp stable. With proper hybrid turbo I'd say over 350hp is doable for a dyno run, and probably a stable 330 - 340hp can be run with same as above supporting mods (exhaust, IC). It doesn't seem like a much of a difference compared to stock turbo, but if you can have your run constantly yielding 20-30hp more, that's a lot on a car like 4C.

1. Just a remap on a bone stock car. In terms of performance / price, just a remap on stock car is definitely the best bang for the buck, but it is impossible to get a stable power over 300hp with just a remap. This setup needs no supporting mods, but OEM exhaust (cat) is the bottleneck and the engine power on a track will be limited once the engine components heat up.


2.Remap + exhaust + intercooler on a stock turbo. Here we have, GMS Stage I + IC + 3" decat. A 15°C ambient temp, with a big cooler feeding air into the IC inlet on the side of the car. We were able to reach such a high rpm power with heavily advancing ignition timing and keeping temps low. Pretty much ideal conditions which you'll never see on a track, so you can't expect to run 334 hp on a track where your IAT is constantly over 40°C or more. On a track, we expect to run at about 290 - 320 hp, depending of the ambient temps.
Rectangle Slope Font Parallel Pattern



2. Hybrid turbo from a 4C owner in France. Intercooler + 200 cell cat (but in OEM diameter of 2.25"). Definitely a less flowing exhaust than in our case (3" decat) and from video of a dyno run I couldn't see any side IC inlet cooling, so perhaps less ideal conditions than in our dyno run. Still, car pulled 340hp very high in rpm range, so I'm sure with a 3" decat and lower ambient temps, it could go beyond 350hp for a single dyno pull, to brag about it. Running effectively and stable on the track, it's probably closer to 330- 340hp. This setup needs, hybrid turbo, exhaust and IC and maybe an uprated clutch.
Rectangle Slope Font Parallel Pattern


3. Custom manifold and turbo. This would be the best solution, but also the most expensive. This setup needs, hybrid turbo, exhaust, IC, uprated clutch, injectors, perhaps even internals (head work - porting, rods, pistons, head gasket) and it is hard to tune it on stock ECU, so this is where things get really expensive and we don't see much of this setups running.

In terms of performance / price, just a remap on stock car is definitely the best bang for the buck, but it is impossible to get a stable power over 300hp with just a remap. From here on, any further upgrade requires supporting mods too, so every additional hp gets expensive. Before going to hybrid turbo or any other turbo setup, definitely OEM exhaust (OEM cat) is main bottleneck and must be upgraded. An intercooler should be a priority too. Once you have these done, then it is maybe time to look into the hybrid turbo. Now back to your initial question. I think the hybrid turbo is not very cost effective, compared to just a remap, but this is the last stage before it gets really expensive and if you're racing then this additional 15-30hp could mean a lot.
 

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Discussion Starter · #5 ·
Perhaps I was a bit too enthusiastic comparing two extremes here - stock vs. hybrid. On stock turbo, you can get 330 hp out of it, for the dyno to brag, but it's hard to keep that power all that high constantly due to lots of heat generation as you're pushing the turbo outside of it's optimal efficiency chart and therefore causing even more heat. On stock car with an aggressive tune, IAT can easily reach over 60°C and at that temps the ignition is already retarding heavily, robbing you of power and if still not enough, boost will be limited. If you have a free flowing exhaust, good intercooler and good engine mapping with high rpm power focus, so you don't boost too aggressively at low rpm's, then you can expect to be in a range of about 290 - 320 hp stable. With proper hybrid turbo I'd say over 350hp is doable for a dyno run, and probably a stable 330 - 340hp can be run with same as above supporting mods (exhaust, IC). It doesn't seem like a much of a difference compared to stock turbo, but if you can have your run constantly yielding 20-30hp more, that's a lot on a car like 4C.

1. Just a remap on a bone stock car. In terms of performance / price, just a remap on stock car is definitely the best bang for the buck, but it is impossible to get a stable power over 300hp with just a remap. This setup needs no supporting mods, but OEM exhaust (cat) is the bottleneck and the engine power on a track will be limited once the engine components heat up.


2.Remap + exhaust + intercooler on a stock turbo. Here we have, GMS Stage I + IC + 3" decat. A 15°C ambient temp, with a big cooler feeding air into the IC inlet on the side of the car. We were able to reach such a high rpm power with heavily advancing ignition timing and keeping temps low. Pretty much ideal conditions which you'll never see on a track, so you can't expect to run 334 hp on a track where your IAT is constantly over 40°C or more. On a track, we expect to run at about 290 - 320 hp, depending of the ambient temps.
View attachment 132704


2. Hybrid turbo from a 4C owner in France. Intercooler + 200 cell cat (but in OEM diameter of 2.25"). Definitely a less flowing exhaust than in our case (3" decat) and from video of a dyno run I couldn't see any side IC inlet cooling, so perhaps less ideal conditions than in our dyno run. Still, car pulled 340hp very high in rpm range, so I'm sure with a 3" decat and lower ambient temps, it could go beyond 350hp for a single dyno pull, to brag about it. Running effectively and stable on the track, it's probably closer to 330- 340hp. This setup needs, hybrid turbo, exhaust and IC and maybe an uprated clutch.
View attachment 132705

3. Custom manifold and turbo. This would be the best solution, but also the most expensive. This setup needs, hybrid turbo, exhaust, IC, uprated clutch, injectors, perhaps even internals (head work - porting, rods, pistons, head gasket) and it is hard to tune it on stock ECU, so this is where things get really expensive and we don't see much of this setups running.

In terms of performance / price, just a remap on stock car is definitely the best bang for the buck, but it is impossible to get a stable power over 300hp with just a remap. From here on, any further upgrade requires supporting mods too, so every additional hp gets expensive. Before going to hybrid turbo or any other turbo setup, definitely OEM exhaust (OEM cat) is main bottleneck and must be upgraded. An intercooler should be a priority too. Once you have these done, then it is maybe time to look into the hybrid turbo. Now back to your initial question. I think the hybrid turbo is not very cost effective, compared to just a remap, but this is the last stage before it gets really expensive and if you're racing then this additional 15-30hp could mean a lot.
Thank you for that very detailed response! That definitely clears up a lot of confusion on my end. I very much noticed the power loss due to heat soak the other day when I was doing some spirited driving down my local country roads. So that makes sense about getting an ideal dyno run compared to real world output. I’m assuming an intercooler is the best effort to mitigate that problem?
 

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Intercooler will more effectively cool down hot air, sure, but it is even more important to not let the charge air heat too much. I'd say exhaust should be first upgrade, followed by the IC. OEM exhaust is very restrictive, due to emission standards so lots and lots of heat is generated there to have the cat work as effective as it can. OEM exhaust flow is ideal for OEM power levels of 240hp by all the calculations and from here on it is the bottleneck. Stock cat, especially. While the OEM Intercooler is not a bottleneck even on a tuned car, the thermal efficiency of quality aftermarket intercoolers is better than OEM, so the air will come out colder. It's like the exhaust is a disease and the IC a painkiller and it's better to cure the root of the issue than patch up the issue.

If your exhaust or the head are not flowing well, then your turbo will work extra hard to reach the desired intake manifold pressure and overcoming the backpressure of the exhaust will require even more work by the turbo, so you're in vicious cycle - you're boosting more but also heating more. Make the engine inlet and exhaust flow better and you'll achieve same results with less boost and less temperature. A hybrid turbo on a stock car would probably be the worst solution.
 

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Intercooler will more effectively cool down hot air, sure, but it is even more important to not let the charge air heat too much. I'd say exhaust should be first upgrade, followed by the IC. OEM exhaust is very restrictive, due to emission standards so lots and lots of heat is generated there to have the cat work as effective as it can. OEM exhaust flow is ideal for OEM power levels of 240hp by all the calculations and from here on it is the bottleneck. Stock cat, especially. While the OEM Intercooler is not a bottleneck even on a tuned car, the thermal efficiency of quality aftermarket intercoolers is better than OEM, so the air will come out colder. It's like the exhaust is a disease and the IC a painkiller and it's better to cure the root of the issue than patch up the issue.

If your exhaust or the head are not flowing well, then your turbo will work extra hard to reach the desired intake manifold pressure and overcoming the backpressure of the exhaust will require even more work by the turbo, so you're in vicious cycle - you're boosting more but also heating more. Make the engine inlet and exhaust flow better and you'll achieve same results with less boost and less temperature. A hybrid turbo on a stock car would probably be the worst solution.
When you refer to OEM exhaust do you mean the race exhaust or the standard exhaust with muffler?
 

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Discussion Starter · #9 ·
So
Makes no difference whether you run standard - muffled or race - not, you're not seeing any changes in terms of performance, because the downpipe and cat are the same - very restrictive.

View attachment 132742
Sorry to get off topic, but you mentioned possibly having to use aftermarket clutches on the setup previously mentioned. How much different does shifting feel with these clutches? Is it very jerky or is the feel very similar?
 

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It's an expensive rabbit hole (just doing it, even more when things start breaking). The benefit is sustained power vs a whole lot more. You gotta first assess your target use of the car.

As a weekend back road driver, I don't need anything more than my remap, intake, exhaust, and wider 300TW rubber. I wouldn't realize a majority of the benefit of further upgrades.

Try an extra car, but a different and faster one if you feel you want more. It'll be cheaper in the when you've had your fun and sell it off (or the 4C if you end up loving it more...)
 

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Discussion Starter · #11 ·
It's an expensive rabbit hole (just doing it, even more when things start breaking). The benefit is sustained power vs a whole lot more. You gotta first assess your target use of the car.

As a weekend back road driver, I don't need anything more than my remap, intake, exhaust, and wider 300TW rubber. I wouldn't realize a majority of the benefit of further upgrades.

Try an extra car, but a different and faster one if you feel you want more. It'll be cheaper in the when you've had your fun and sell it off (or the 4C if you end up loving it more...)
I absolutely love the 4C and i’m in no rush to make a massive change. My last car was a supercharged Shelby GT350 that made about 800hp at the tires, so I do kind of miss the tire roasting power and the punch. I get that the 4C will never be that and i’m glad, but another 100hp never hurts 😉
 

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I absolutely love the 4C and i’m in no rush to make a massive change. My last car was a supercharged Shelby GT350 that made about 800hp at the tires, so I do kind of miss the tire roasting power and the punch. I get that the 4C will never be that and i’m glad, but another 100hp never hurts 😉
Well, until it does. I've lived around these OEM lightweight cars for a good decade now and the one commonality I see is that they only have so much of a threshold for a boost in torque output until things start breaking (forget HP for a minute). The gearing only stays fruitful to a point, heat generation rate climbs everywhere, axles break as you up the stick, maybe you gotta chop fenders to fit enough rubber, etc. You gotta be intentional with where you're adding the extra power too (like maybe on 3/4th gear and beyond).

I see Gale's posted torque curves and they don't look all that different for the work done on the hybrid turbo, but I totally understand, it won't be as heat limited. Also, larger displacement (and more cylinders can't hurt) engines have better scalability when you add boost. Base Corvettes with a blower can make lots of power too for not much relative investment. The nice thing is that the longer wheelbase and the gearing is tall enough to not "hate" living with all the power long term.

I'm not suggesting to shop the polar opposite spectrum, but maybe a GT is more to your liking and pushes total performance another 30% (Evora GT comes to mind) without compromising the 4C.
 

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Discussion Starter · #13 ·
Well, until it does. I've lived around these OEM lightweight cars for a good decade now and the one commonality I see is that they only have so much of a threshold for a boost in torque output until things start breaking (forget HP for a minute). The gearing only stays fruitful to a point, heat generation rate climbs everywhere, axles break as you up the stick, maybe you gotta chop fenders to fit enough rubber, etc. You gotta be intentional with where you're adding the extra power too (like maybe on 3/4th gear and beyond).

I see Gale's posted torque curves and they don't look all that different for the work done on the hybrid turbo, but I totally understand, it won't be as heat limited. Also, larger displacement (and more cylinders can't hurt) engines have better scalability when you add boost. Base Corvettes with a blower can make lots of power too for not much relative investment. The nice thing is that the longer wheelbase and the gearing is tall enough to not "hate" living with all the power long term.

I'm not suggesting to shop the polar opposite spectrum, but maybe a GT is more to your liking and pushes total performance another 30% (Evora GT comes to mind) without compromising the 4C.
Break things and build back stronger? Stop! You’re getting me too excited hahaha
 

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Break things and build back stronger? Stop! You’re getting me too excited hahaha
Hey if you wanna go for it with eyes wide open, we're very excited to hear about the end state of the journey. I love a reliable +100HP in a sub 2500 lb car. I've setup 2 of my Miatas to be right there at +150/200 HP respectively and still be only a strong $50-70 worth on maintenance costs (oil and 300TW B class summer tires).

It's been really hard for me to get excited about anything else beyond my Lotus, 4C, and these 2 toys.
 

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On the issue of exhaust modifications, if you delete the cat doesn't that mean you will fail noise tests on any track? I have the race exhaust and I'm already pushing over 100db. Is there a solution to have a less restrictive box without upping noise?

Many thanks
 

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On the issue of exhaust modifications, if you delete the cat doesn't that mean you will fail noise tests on any track? I have the race exhaust and I'm already pushing over 100db. Is there a solution to have a less restrictive box without upping noise?

Many thanks
You can add a muffler or turn down tips that route the exhaust sound into the ground. Exhaust restrictions like cats near the engine where the exhaust is hottest have the biggest impact. At the end where it is cooler is less of an impact.

Cats in the header are the worst.
 

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The beauty of this hybrid turbo kit is that the power is up by 100 bhp and the car will pass all emissions tests, noise tests and it looks identical to a standard car so there are no insurance issues, its a win, win solution. The kit is bolt on and can be fitted in under 6 hours. I run the earlier kit on my car and have done for six years and I have had no reliability issues. The second generation kit has more top end power than the original kit and makes the engine feel altogether sportier with more top end rush.

I do have some issues with both aftermarket inter coolers and cold air kits that I have seen fitted to the 4C. With inter coolers and intake systems if they are not sealed to the inside of the wing and there are gaps around them where the air can simply flow around the cooler/intake then they are worse than useless. If you look at a standard car both the inter cooler and the engine air intake are in sealed compartments, you can see this for yourself by looking in the scoops, the engine intake is in the outside of the right hand vent, all the air that goes into the side intakes at whatever speed you are doing has to either go into the engine or through the inter cooler and it is forced through there by the velocity of the car, Alfa Romeo did spend quite a lot of time designing both these systems and in my opinion they did an extremely good job!
 
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