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Akrapovic adapter prototype finished. Now off to production...

With this adapter you can keep your Akrapovic rear exhaust while replacing the rest of restricting, stock exhaust system, with GMS 3" Modular exhaust components. Just plug and play.

View attachment 109807
Are Akrapovic actually for sale if you don't have it OEM ?
 

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Are Akrapovic actually for sale if you don't have it OEM ?
Hello, found this exhaust which looks like a Akra set up, but its not. It seems to be an oem set up.

Mabe Rene @ Qverde can chime in for more info????

 

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Biggest advantage of an Akrapovic is its a valved system imo. As I use her as my daily, I dont want noise all the time. And I expect more and more tracks making issues of loud exhausts, dont they Olo?
 

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Discussion Starter #327
GMS 3" Modular exhaust system adapter for Akrapovic rear exhaust silencer and for stock rear silencer or stock race exhaust, now available, on stock.


AKRAPOVIC ADAPTER 1.jpg
 

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GMS 3" Modular exhaust system adapter for Akrapovic rear exhaust silencer and for stock rear silencer or stock race exhaust, now available, on stock.


View attachment 110339
YES!
 

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Discussion Starter #329 (Edited)
On tuned engine (basic tune, usually named stage I from different vendors, designed to work with stock engine and turbo), 275hp in my case, without any additional mods to the engine or engine map, a 16hp increase with GMS 3" decat and 11hp increase with GMS 3" 200 cell cat was gained, which is the result of free flowing GMS 3" exhaust and lower backpressure. In my case that was 291hp with stage I map and GMS 3" decat system. The lambda values are still within the closed loop "self-adjustability" range, so the car runs without any issues, without any additional engine mapping. The heatsoak is significantly reduced and power curve moves slightly towards higher rpm range providing a decent and stable track setup. Wise choice for those who already have tuned engines.

Next step, we installed bigger IC (from Scara73) and measured the exact same setup again (stage I remap + 3" GMS Decat) and we gained another 14hp in the upper range and even further reduced the heatsoak with better IC cooling capacity. Dyno measured 305hp and 390 Nm.

Now the good part. We cranked the boost, advanced the ignition timing and leaned the fueling a bit as the engine felt stable and we got 430Nm and a whooping 342hp at 5900 rpm. Due to safety reasons, we lowered the boost in mid range, got rid of the low rpm surging and kept it high in upper rpm range re-added some fuel and ended with 380Nm and 335hp at 6400rpm. I'd say a nice gain over stock 239hp we have measured. It's the same 1.75 Tbi engine with only GMS 3" exhaust, IC and GMS Stage I tune (in development), but now pushing safely 335hp with higher rpm powerband which is exactly how I wanted the track engine to be like. Not too much of instant torque at low rpm to prevent transmission issues and higher rpm peak power providing more racey engine characteristics.

So we finally got the dyno numbers and proved the result of hard work on the GMS 3" exhaust components. More on ECU tuning will follow and dyno measurements and videos will be posted. Stay tuned.
 

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On tuned engine (basic tune, usually named stage I from different vendors, designed to work with stock engine and turbo), 275hp in my case, without any additional mods to the engine or engine map, a 16hp increase with GMS 3" decat and 11hp increase with GMS 3" 200 cell cat was gained, which is the result of free flowing GMS 3" exhaust and lower backpressure. In my case that was 291hp with stage I map and GMS 3" decat system. The lambda values are still within the closed loop "self-adjustability" range, so the car runs without any issues, without any additional engine mapping. The heatsoak is significantly reduced and power curve moves slightly towards higher rpm range providing a decent and stable track setup. Wise choice for those who already have tuned engines.

Next step, we installed bigger IC (from Scara73) and measured the exact same setup again (stage I remap + 3" GMS Decat) and we gained another 14hp in the upper range and even further reduced the heatsoak with better IC cooling capacity. Dyno measured 305hp and 390 Nm.

Now the good part. We cranked the boost, advanced the ignition timing and leaned the fueling a bit as the engine felt stable and we got 430Nm and a whooping 342hp at 5900 rpm. Due to safety reasons, we lowered the boost in mid range, got rid of the low rpm surging and kept it high in upper rpm range re-added some fuel and ended with 380Nm and 335hp at 5900rpm. I'd say a nice gain over stock 239hp we have measured. It's the same 1.75 Tbi engine with only GMS 3" exhaust, IC and GMS Stage I tune (in development), but now pushing safely 335hp with higher rpm powerband which is exactly how I wanted the track engine to be like. Not too much of instant torque at low rpm to prevent transmission issues and higher rpm peak power providing more racey engine characteristics.

So we finally got the dyno numbers and proved the result of hard work on the GMS 3" exhaust components. More on ECU tuning will follow and dyno measurements and videos will be posted. Stay tuned.
Did you also install the Scara73 aluminum intercooler pipes?
B5ECE7A5-ECA7-440F-A4D8-CCE59023AC7E.jpeg
 

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380nm, smoother/longer-lasting transmission, corrected/improved heatsoak, and likely bellissima musica from the pipes... What a talent of parting me from my money.
I still haven't decided between the Nitrons or Intrax or go full Ohlins, and now you have me certain I have to do an engine once-over before tuning the dampeners, along with the turbo to IC pipe and Oil Catch Can. Added up, that's nearly $10k all in - and here I thought the 4c was a bargain sports-exotic.
Well - it is, given you can Scara73/Koshi carbon everything, have 3g's + of smooth suspension, and make 1990's "V8" power of ~350hp in the midship, all handmade in Italy by the oldest marque, for less than $100k. Some people would say, such a machine can be classified as a true Demi-Pagani... Half Pagani for 1/15th the price and still wears the Alfa Romeo badge (isn't a kit car)? Hell yeah.
Damn Rudy, you're killin' (me) with them white-hot mods!
 

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@OriginalForza - Yes he is! I have gotten the Rear Arms, Exhaust, Engine mount, & Big Brake Kit from him in the last 3 months... Plus got the EuroCompulsion Intercooler last night because the Black Friday had it down to $1600, which is a much more reasonable price.
 

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Will you be able to give all dynos overlayed so that we can easily compare the different options?
 

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Discussion Starter #339 (Edited)
Did you also install the Scara73 aluminum intercooler pipes?
I run GMS turbo to IC pipe and Samco silicon hoses.

380nm, smoother/longer-lasting transmission, corrected/improved heatsoak, and likely bellissima musica from the pipes... What a talent of parting me from my money.
I still haven't decided between the Nitrons or Intrax or go full Ohlins, and now you have me certain I have to do an engine once-over before tuning the dampeners, along with the turbo to IC pipe and Oil Catch Can. Added up, that's nearly $10k all in - and here I thought the 4c was a bargain sports-exotic.
Well - it is, given you can Scara73/Koshi carbon everything, have 3g's + of smooth suspension, and make 1990's "V8" power of ~350hp in the midship, all handmade in Italy by the oldest marque, for less than $100k. Some people would say, such a machine can be classified as a true Demi-Pagani... Half Pagani for 1/15th the price and still wears the Alfa Romeo badge (isn't a kit car)? Hell yeah.
Damn Rudy, you're killin' (me) with them white-hot mods!
I appreciate your thoughts. Believe it or not, positive feedback and desire for GMS parts makes me happier than the sales itself. I take the sales as a "must", to keep the funds flowing for development and 2020 is really a breakthrough in terms of development. I'm so happy that I have managed to get all the right people cooperate with GMS. The ECU team, the carbon team, the welder, CNC machinist. The picture is really coming together and I really need to hold back myself not to do something too crazy, because I know we can do it, just don't think it is time yet.

@OriginalForza - Yes he is! I have gotten the Rear Arms, Exhaust, Engine mount, & Big Brake Kit from him in the last 3 months... Plus got the EuroCompulsion Intercooler last night because the Black Friday had it down to $1600, which is a much more reasonable price.
And more upgrades are coming... o_O

Interesting. Curious to read figures :)
Any update on the anti roll bar fix in the meantime ?
More testing needed. On the bench, everything good, but I want more track time testing. It's a 2021 release date.

Will you be able to give all dynos overlayed so that we can easily compare the different options?
I have all the graphs saved, but cannot overlay all of them as I have changed the ECU team in the past year so some graphs are from previous dyno. The graph comparisons are only valid if they are all done on the same dyno, same operator and exact same setup of dyno run (length, tire pressures, tire diameters, temps, etc.). Having same car on 2 different dynos will never show same results. It doesn't really matter how high the figures are, but how much of increase there is from one mod to another. This is the only valid point, measuring the increase, not the end figures. But as the customers tend to make a decisions which tune they'll buy, according to the dyno numbers - the one that shows the most gain, obvious, the dyno graphs are in 99% cheated. Tires overinflated, extremely low IAT, short runs and altered ignition timing to make a single pull dyno queen. You can get serious hp out of stock 4C for a single dyno run without any mods at all, but on the track you'll fall behind against properly modded 4C with lower hp, but stable tuned engine map so much that it will be embarrassing. Now back to the point. I have all the important graphs done on the same dyno and dyno setup, so the results can be compared and I'll make an overlay of it, although the lap times is the thing I'm looking forward to confirm the dyno results.

@GMS If the tail center exit exhaut is without resonator. will it sovle the sway bar issue?
Thanks
Yes, it will.
 

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I have all the graphs saved, but cannot overlay all of them as I have changed the ECU team in the past year so some graphs are from previous dyno. The graph comparisons are only valid if they are all done on the same dyno, same operator and exact same setup of dyno run (length, tire pressures, tire diameters, temps, etc.). Having same car on 2 different dynos will never show same results. It doesn't really matter how high the figures are, but how much of increase there is from one mod to another. This is the only valid point, measuring the increase, not the end figures. But as the customers tend to make a decisions which tune they'll buy, according to the dyno numbers - the one that shows the most gain, obvious, the dyno graphs are in 99% cheated. Tires overinflated, extremely low IAT, short runs and altered ignition timing to make a single pull dyno queen. You can get serious hp out of stock 4C for a single dyno run without any mods at all, but on the track you'll fall behind against properly modded 4C with lower hp, but stable tuned engine map so much that it will be embarrassing. Now back to the point. I have all the important graphs done on the same dyno and dyno setup, so the results can be compared and I'll make an overlay of it, although the lap times is the thing I'm looking forward to confirm the dyno results.
Completely agree, absolute numbers does not matter much, and there are several ways to "cheat". But dyno is the best(or should I say least bad?) reference we have, we can only hope suppliers are honest when testing. So if you run before and after numbers with nothing else changed, it should give a pretty good idea how performance is changed. Then, if two 4C with same driver, and only main difference is in power, and still has the same laptime, we know that one of the suppliers are giving optimistic numbers.

Must say, I like your approach of not maximizing low end torque for several reasons. Slower of the line in a drag I assume, but better to drive at the limit, more engaging and saves trans.

If I was developing, I'd put some effort in making throttle response more linear as well. AW Race ECU was in my opinion a big improvement in this regard, just for reference.

Are you planning to deliver a cloned ECU as well, so we can keep OEM ECU as a backup?
 
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