tricky tricky... might be a fun one to figure out

 

Yea...tricky indeed. Either way im happy, car is at 25* timing and no knock and low iat2...that tvs just wants to keep making power. Cant wait till next year when i build the engine up..lol

 

Nice build man.

Im not sure how strong the Cobalt axle shafts are, but if they are anything like a Cobra shaft, any wheel hop will kill them.

I have DR's for the street, and it doesnt seem to hop, but for a hard launch at the track like 4.5k RPM, I have a set of Bias Ply ET Streets. They will absorb the shock of the drive train, where as a stiff sidewall DR will not.

1 tenth in the 60ft is good for at least 2-3 tenths on the big end.

 

yea i need to get my 60ft better. i launch at 2000rpm and no wheel spin or wheel hop...had abit of wheel up when i tried to go up to 2500 but i think it was just cuz i accidently dumped the clutch

 

Ok so i just dynoed the car. iiunno if its abit low or what....i was hoping 300whp. I always did 3rd gear pulls before....this time we did 4th gear pulls so i dont know how that effects the change. Anyways the car put down 281whp and 249trq @ 7000rpm...the power never dropped either so it can make more power at higher rpm but thats as far as im pushing it on stock internals. I had them load the dyno graph on my usb flashdrive but it got fucked up so ill go back there tomorrow to get a print out and post it. Honestly im not really happy with what its putting down, considering how much money i put into this thing. So iiunno what the future has in store for the cobalt. This past year i really been leaning towards a nissan 350Z or 370Z since those are now out. So im thinking next summer i might sell the cobalt and get a 350 or 370...iiunno tho. Uploading a video now of the dyno pull.

 

Were you monitoring the car with hpt during the pull? I would maybe suggest doing 2nd, 3rd, and 4th gear pulls on the dyno, and maybe 2 pulls in each gear to compare.

It would be nice to monitor conditions on the car while on the dyno.

What are you commanding for afr at WOT? How much timing advance? What kind of dyno were you on?

 

im commanding 11.9AFR and 25* timing at the top of WOT. We did 3rd and 4th gear pulls and it only changed by 4whp...and no i wasnt monitering it with hpt during the pull...just the dyno jet stuff.

 

The gear is not going to make much of a difference, I would not give up on it yet. It seems that you love your car as you had plans to build up a motor over the winter, I would keep it and work with what you have, rome wasnt built in a day. I can tell you too, from the stock pulley to a 2.9" pulley the gain is very noticeable. Problem with the stock pulley is the slow build in boost and lack of low end torque.

 

i agree on that...but i put alot of money into the car already and if i do what i wanted to do, its going to be another $7000...give or take. Even then i would maybe see 350-380whp. Not worth it...i love the looks of the 370z so im gonna go that route

 

Try bringing the commanded afr down to 11.2 or so and retouch the afr error and timing to correct and then re-dyno.

 

nah...even then man its not worth it. I spent way to much money on a 2.0L 4 banger...i want something better.

 

Ya for sure. Does this mean you're going to be keeping the m62 then?

 

yup...for this reason. I knew if i sold it and then wanted to sell the car it would kick me in the ass. Question though. 3.0" pulley should run fine on stock injectors right?

 

Wouldn't risk it. stage 2 pulley is a tiny bit bigger than that, and stage 2 runs 42 lb injectors.

 

true...hmm..but if the tune is changed around then it should run fine on stock injectors with a 3.0...just change the afr and lower the timing.

 

I dunno. You can try it and see. After retuning it, do WOT pulls and watch inj pulse widths. You can watch inj duty cycle %, but its highly inaccurate. Steve should know all about this, And he's prolly gonna retune you anyways, so make sure you check with him. I think its 20 msec's where injectors max out.

 

well we will see...if i dont get a offer on the 60lb that r in the car right now ill just leave them in. The question is...can a meth kit work on the 370z..lol

 

If it's not boosted, I doubt there is any point.

 

Selling the TVS then??

 

hmmmm if you part out i might be interested in the rotated mounts

 

heading to the dealership after PT this morning so ill be making my mind up shortly

 

we used to be in the low 11s on his first tune.
after we bumped it up it definately made more power.





snake do you have any previous results from that dyno?
anything to compare it to?
dynoing once means nothing without a point of reference.

btw whos dyno was it?

 

we did 4 pulls. 1 in 3rd gear to compare to what the car did in NS and the other 3 were in 4th gear. When i dynoed the car in NS it was all in 3rd gear. Like i said the file got messed up so i cant post what i did yesterday. But the AFR was better then when i had the car tuned from the other car. Between 2500rpm and 4500rpm the AFR is what we commanded it to....11.9 But then after 4500rpm it goes to 13.0 on there wideband. Which is about 12.5. As for the dyno graph itself. Remember that issue u fixed at about 3500rpm? well its still showing a little drop in power at that point. Back in NS it goes up and then at 3500rpm it drops 50hp and then goes back up. Now that the car is retuned and new parts it goes up and at 3500rpm it drops about 20hp...cant notice it while driving but the dyno shows it. Maybe thats why im seeing 281hp and not 300hp like i wanted.

And i dynoed at horsepower solutions (dynojet)

 

that is likely the tipping point for PE showing up
below that RPM it will stay a bit leaner so that you dont bog, then past that it will go to full power enrich.
it could also very likely be your meth kicking in, which will cause a quick richening up of the fuel mix.
if you want to keep that HP, your likely going to have to run increadibly lean.
which will probably feel great.
for about 3 days


but the point with dynos, is that your numbers mean absolutely nothing, without a point of reference.

if you havent dynoed there, or know of another stockish cobalt that has dynoed there, then its hard to give any relevance to the numbers at all.
if the graph said 305hp what would be different?


edit: did some digging to show what i mean.
2005 6.0L GTO with CAI at HP solutions 335hp

same type of car, on different dynos:
2005 6.0L GTO stock 355hp
2005 6.0L GTO stock 353hp
2005 6.0L GTO stock 322hp
2005 6.0L GTO stock 368hp

see how pointless the numbers are?

 

yes it will. but will you be able to tune for it