I just dyno'd my car on Tuesday the 14th. I made 315 whp, but, I had a major change in slope at 6000 rpm. The hp to rpm rose steadily until 6000 where it broke sharply and continued to rise slowly from there. Is this a typical TVS trait or is this something more specific to my car?

My Atom uses a straight through 3" exhaust that terminates to Supertrapps. The Supertrapps had 10 wafers a piece on them. After the dyno several fingers pointed to the Supertrapps, unfortunately to late for that session. Other than the exhaust, I think that all other items are very similar to what you guys are using in your Cobalt's. 2.0L LSJ, LS4 TB, 60 lb injectors, return style fueling, valve springs, K&N cone filter with about 18" straight pipe to LS4

If this a typical trait, I will quit wasting time to find the anomaly and go straight into the head and cams using tried and true better breathing techniques.

Specifics as to what I am doing are in the thread "Dyno for a Harrop in an Ariel ", response 86 refers to the dyno https://www.cobaltss.net/forums/show...=157228&page=5

 

Oh hi, just stepping in to say

TVS Atom? fapfapfapfapfapfapfapfapfapfapfapfapfapfapfapfapfa pfapfapfap

 

omg. that car must FLY

 

#1. Supertrapps are deadly take them off and attenuate noise differently.
#2 forget the LS4 tb,
#3 fix the exhaust ports in the head
#4 make sure you have the right injectors and PM area47 to tune

#5 q.e.d. Fixed

 

If you could please post a copy of the dyno sheet so I can see it. FYI though 315whp is about average on a bolt-on lsj with an average tuner. Porting the Head is where you will see a HUGE gain.(did i mention HUGE)

winner winner chicken dinner

 

Ditch the supertrapps, port and polish the head.

That car is bad ass! Congrats!

 

are you using the lsj computer? did you ensure the boost control solenoid is not active? What happens to mass airflow, spark timing, and boost?

 

#1 My first experience with Supertrapps on anything that moves a lot of air. I had a PM from someone that track races an Atom and he stated that he is running at least 23 not 10. If I take them completely off, the car is just to loud. Do you know of another attenuation option?

#2 My tuner will be over on Tuesday to fix my drive ability issues, but, I am about ready to take it and drive over it many, many times

#3 I am going to do a fully ported head and just switch them at some point

#4 I have 60 ib injectors and was unaware that Area did mail order tunes

#5 Maybe I am being dense, but, I don't know what you mean here.

Thanks

Yes, we are using the LSJ computer. I am not the tuner, so, I will ask on your other three questions, I can answer that boost remains consistent at 22 lb and that nothing radical is happening with timing

 

John, why don't you like the LS4 TB? you have to set the scalar pretty high but it's not that bad...

 

What pulley are you running?

 

Ok for the head just port the exhaust, for noise attenuation I recommend a cat, the longest resonator/diameter you can package and a Corsa Daytona Prototype muffler and a turn down at the tail pipe....the injectors are okay and I now (after some work here) can say I consider area47 the most awesome of tuners, and for $ he will (maybe) work for you

'Q.E.D.'= Quad Erat Demostratum. : "That which is demonstrated"....goes at the end of every succesful solved equation...

s**t. cant spell it any other way. And the power it adds ? not worth pouring milk on that cereal....

 

80 mm

Good information .... Thank you!

 

from what i've seen it adds anywhere from 7-11 hp al across the powerband. I'll have to get some before and after pulls to really see for myself.

 

just do it and drive it for a couple of days. then you will take it out and someone else will buy it and the circle jerk will continue

 

hahah, ok John. now i know why you don't like it.

 

I haven't given up on it yet, but, just imagine it in a 1350+/- lb car! The little hiccups slam you in the seat and make you look really talented as a driver, ... can't wait to get it tuned right or out of there!

 

my dyno curves run flat after 7400 and hold that power in variance of .3-.5 whp to 8k when i slam into the rev limiter. it is a characteristic of the blower itself. you do not need the ls4 tb to get the power you want.

 

Thanks Area! You have confirmed my thinking.

The Supertrapps need to come off or I need to add a bunch more. The other Atom that uses one use a 5" dia version and I use two 4" dia ones. He uses 23 - 5" discs. This means, .... 2x3.14159x2.5x23=361.3" of total disc circumference for the 23. 361.3/(2x3.14159x2)=28.75 discs for me to achieve the same circumference. Basically to achieve the same flow, I need to add 9 discs, however, I had 20% more air flow at 6000 rpm than the other Atom that dyno'd the same day. This means without anymore gain from the Harrop (which keeps going to 7400 rpm) I need a total of 34.5 discs. I am thinking to dyno with an open exhaust and then with 20 discs per side. I am thinking that this is going to be too loud for my tastes

We will see! Thanks for the information

 

I went the supertrapp route its crap. Sorry. I dyno'd the plates its awful...you gotta find a different way add plates it makes it worse and worse....

 

Exhaust on these things is a real pain. No room! I currently have two 2.5" V-band flanges pointing straight back. I am first going to try to maintain this system, just from a cost stand point, before scrapping the entire mess.

 

send me picktars. Can you mount a muffler transversely?

 

simple question but has the MAF been rescaled? it could just be maxing out airflow at that rpm

 

I am here at the office and I left the Atom at home, because, I got really sunburned yesterday. It is basically a really fast tanning bed ...

These are in my pictures:





I will ask the tuner, very good question!

 

how much was this thing stock?!

 

<3<3<3