quick.... closed cutout = a lot faster.


I've been disappointed in my heads/cam 847 car for a while now, so today I decided to close my cutout and see if there was any difference. There is a huge difference. Before the car felt like it was back to bolt-ons plus a NX 75 wet kit with the cutout open, now with the cutout closed the car feels like it did when it was bolt-ons plus a NX 150 wet kit. Which is exactly what I was expecting out of the car.


All I can say is I am happy with the car again. With the cutout closed I did a slow roll down a back road near my house. Rolling at 30mph I stabbed the gas and the Mickey Thompson DR's did there job and hooked untill the car hit 5200RPM from there it spun the tires threw 6800 where the car shifts in to 2nd and continued to spin the tires almost until the car shifted in to 3rg gear. It put a big grin on my face!

 

It probably just feels faster because its alot quieter.

 

Ummm.... no. Huge difference and it really isn't much quieter at all.

 

guess every car is going to be different depending on the mods. I gained 15rwhp with my cutout open. Glad your happy with your car again.

-brian

 

<- Not a big fan of cut-outs

-Dustin-

 

Closing the cut-out lowered your RPM band a little giving you a little more SOTP feel, I bet you actually lost peak power though. Depending on the use for the car, a lower RPM band may suit you well Glad you're enjoying your ride

 

Does nobody read here? lol... With the cutout closed the car has a lot more power all around, ESPECIALLY up top.



But whatever, I am just happy with the car again.... for now, lol.

 

Hopefully I will be able to go to the track Wednesday and find out for sure. I was gonna go tonight but it started pouring out...

 

According to the ***-dyno mine feels softer with the cut-out open. Even up top it feels no different. When I go to the dyno I will be getting a pull with it open and closed.

With my stock all bolt on motor I gained 2 RWHP with it open.

 

Yup

-Dustin-

 

^^Thank god I'm not the only one^^ When I bought my car it had one......and that was the first thing to go

 

I think what some of these guys are getting at is do you have dyno numbers to prove this theory? With the cutout open I don't think anyone has lost power, some may gain little to none depending on what catback you have, but I don't think a loss is going to happen. With the cutout open and the car louder, it gives the illusion of being slower, when it is actually faster, probably causes very slight upward shift in the powerband too. Just like a stock LS1, some think they feel slower due to the LT1's low end and flat torque curve, however we all know that is not the case. I thought the same thing when I put my cutout on, loved the sound but didn't feel as fast, however ended up dynoing it both open and closed and I gained 8 rwhp and 5 rwtq on the dyno with only a catback and CAI. Point is, whether or not the 'butt dyno' shows a change for the better with it closed, that doesn't mean that is the case.

The important thing though, is that you're happy with it.

 

I am curious...what kind of exhaust do you have in the back? Also its quite possible your cutout isnt placed right for the pulses in the exhaust. Anyhow..congrats.

 

Thats good your happy with your car again. I installed a cutout on my car, because it was supposed to be good for somewhere in the neighborhood of 7-10rwhp/tq. I only pick up 2hp/3tq with mine....which is absolutely nothing for SOTP. Like others have said, my car does feel slower with it open but I think its just because it so obnoxiously loud...and the only time it sounds good with the cutout open is idle & WOT. I wonder if maybe your knock sensors pick up the excess sound as knock and retard the timing with with your cutout open....that would explain a loss in power.

 

Maybe with it open, it is so loud that you are picking up false knock and getting knock retard. That could be one explanation for the change, and possible improvement with it closed.

Edit: I see that 89385formula beat me to the knock retard possibility...

Dan