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View Full Version : First Dyno Experience, HORRIBLE!!!


mojosvt
03-19-2006, 07:30 PM
Well, It was like christmas, I was so excited that I could not sleep last night. Drive to the dyno shop with a smile ear to ear. Swap out the stock pulley for a 2.76, along with the billetflow 4 piece set. No Problem.... Get her up on the dyno, start doing some little check, everything perfect. Start doing some small pulls to 3000 rpm, the a/f ratio, is all over the map. But everything else is near perfect, front os sensors, fuel pressure, maf flows, the power curve was flawless, but still the a/f is up and down and up jumping all over the place between 14 and 11. so we assume that there must be an exhaust leak, and not actually that lean, because the power was perfect. I don't think you could put down 488 rwt @3000rpm with an engine that lean. So we swap out the rear O2 sensor, and swap out the tailpipe siffer and hook it up on the o2's place. Almost exact same line..all over the place. double check and make sure the dyno is ok, put another cobra up, perfect 11.3 a/f line. so wer recheck where the x-pipe meets the headers, no leaks... WTF:mad: !!!!!! So i ended up having to leave without any tuning, just running the Xcal2 tune, with a supposed a/f bouncing between 11 and 14. Any suggestions would be great.Thanks guys, Mike

Dave B.
03-19-2006, 08:09 PM
Ok the RWTQ was 488 but what was the RWHP ???

mojosvt
03-19-2006, 08:51 PM
Sorry, I put down 466 rwhp, and like I said, perfect curve.

Dave B.
03-19-2006, 08:56 PM
Ok so you got 466 RWHP and 488 RWTQ ??? is that correct?
if so, thats about right for a 2,76 pulley, before my stage 4 i had 468 RWHP and 485 RWTQ so what you got would be right on the money, do you have any headers, or a differant heat exchanger ??

cobrabitn
03-19-2006, 10:13 PM
You guys are killing me! Do you know what it is like to read all of this knowing you have Mystichrome in the garage just waiting to be pumped up another 100 rwhp? Sheeshh... I'm choking here! :drool: :doh2: :edmond: :banghead: :retard: :banana: :yup: :flush: :crazy: :burnout: :tongue: :scratch: :touche: :shockwave :starwars: :facedrop: :edmond:

Mike, Come to Charlotte!

Wish we could have got the rest of the Buckeyes to come to Autofair on Saturday and do the AX on Sunday! :thumbsup:

03slidewayzSVT
03-19-2006, 10:21 PM
Tony, Get out of the rocker and get the phone and start ordering some parts hehehehe:D Torrey could you give Tony here a little help here???? sound like someone has tooooo;)

cobrabitn
03-19-2006, 10:26 PM
I already have a 2.80 pulley and a pulley puller that was given to me. I thought I would go with just a lower pulley for now, a 4lb type? What sort of hp increase will I get from that? Do I really need to get different idlers with that set up?

P.S. I just spent 6.5 hours doing the club's financial report, I don't have time to make phone calls... :rotf:

03slidewayzSVT
03-19-2006, 10:36 PM
from what? 2.8 pulley and 4lb lower or just the 2.8??? and nothing else??? :doubt:

cobrabitn
03-19-2006, 10:39 PM
Either or?? With a 2.8 only or with a 4 lb lower only...

spincobra03
03-19-2006, 10:42 PM
cobrabitn I just changed to a 6lb lower and you will need an alternator pulley with the lower changed, as for hp increase with the lower and upper im not sure but I would assume it would have to be retuned. To give you an idea I was 385 rwhp and 405 rwtq and after the 6lb lower I was 465 rwph and 513 rwtq. From what I have been told the lower should give you bigger tourqe increases, slighty more than hp. As I said I dont know about both upper and lower combo, when I spoke to rob at pro dyno he just said it was easier to just change the lower rather than change all the idlers and upper because by just changing the lower I would see the same hp but much more tourqe by going with the lower.

cobrabitn
03-19-2006, 11:30 PM
Do I need to change the alternator pulley with a 4lb lower or will I have charging problems if I don't? If I can get 475 rwhp with a tune and a 4lb lower then I'll be going that route for now till my hp hunger strikes again! :D

03slidewayzSVT
03-19-2006, 11:40 PM
I believe anything more than a 2lb lower you need and alt. pulley. I think there only $25-30 dollars. I think 475rwhp without CAI and exhaust is not happening...:D

cobrabitn
03-20-2006, 04:19 AM
I have a JLT and Magnaflows! :thumbsup:

mojosvt
03-20-2006, 07:44 AM
Yeah, stock headers, and stock HE. I personally went over every single bolt on the x-pipe and the cat back, there are no leaks. Have set up an appt with dan on the 7th of april. Hopefully can get her running right before the 411. Any other suggestions would be great, thanks

Ram77mus
03-20-2006, 12:30 PM
You will need a alt. pulley with anymore then a 2lbs lower. A 2.8 upper work very close to a 4lbs lower. People don't like to spend the money on the lowers because they are $300+, but if you add up all the parts to put a 2.8 on (2.8 =$65+, idlers $150-$250) you end up spending the same amount. SPINCOBRA03 seemed to have very good luck with just a 6lbs lower:thumbsup:

mojosvt
03-20-2006, 01:57 PM
Rob, i talked with Dan yesterday, and set up to see you guys on april 7th with rick as well. Do you have any insight on my issue. I hopefully will solve the problem before I see you guys, but that way you know what to expect

blk04cobra1
03-20-2006, 05:35 PM
Tony, I'll make the same guarantee that I did with Robbie...if you dont like it, we'll buy it from...I guarantee it'll be like driving a new car and you'll never wanna go back...hell, we've got Robbie wanting to do a ported blower now :thumbsup: , but he also needs a few suspension parts to help out with the wheel hop :rotf:

03slidewayzSVT
03-20-2006, 05:47 PM
I just ordered my Steigy. Stage 4 blower today with the 2.76 billetflow pulley. I can't wait 500++ :thumbsup:

spincobra03
03-20-2006, 06:32 PM
I would say def yes on the alternator pulley and he right its worth the 35 bucks for it, but I think you should go with the 6 lb for more tourqe, i would ask rob to see what he thinks, but you are correct I have a k&n intake and only flowmaster exaust and tips, stock h pipe however, but soon I will have a magnaflow cat back system. With a 6 lb lower and the cai and exaust you will easily see 465 and over 500 tourque

spincobra03
03-20-2006, 06:41 PM
hey slideways with all those mods coming and the port, let alone without the NOS are you gonna have to change the injectors, I was under the impression right around 517 rwhp on these cobras thats around the time the injectors have to get changed? But thats only what ive heard

03slidewayzSVT
03-20-2006, 08:06 PM
spincobra, I'll have to see. Rob @ PRO-DYNO is making 530/560 with stock injectors so I guess I'll just have to see:thumbsup:

blk04cobra1
03-21-2006, 09:27 AM
spincobra, I'll have to see. Rob @ PRO-DYNO is making 530/560 with stock injectors so I guess I'll just have to see:thumbsup:
He'll be fine with the stock injectors on the port alone...if he adds a shot of N20, i'd suggest 55lb injectors and a BAP :thumbsup:

mojosvt
03-27-2006, 11:16 AM
Just to get everybody up to speed. During the course of last week, I took of my JLT and found the top bracket to be slightly off the TB, and also the way that the MAF and fliter were sitting, there could have been air leaking in after the MAF and before the intake tube. I got that all straightened out. Then I dropped my x-pipe. Tig welded in a a/f bung, and then used some copper sealant to make sure the x-pipe sealed well with the header to make sure there was no leak there as well.

The results were positive. The a/f stopped drifting lean towards the end of the run, and there were no large lean spots around 4000 rpm. However, we still could not get the a/f really smooth. The only two things that seemed odd to the tuner were that my battery was dropping to 13.3 to 13.4 volts during the run. Is that normal? He also had to bump up my injector pressure to 45# form 40#. As we left it i put down 473rwhp/503rwtq, and my a/f bounced arround from 11.1 to 12. Should I be worried about this? Should I be worried about having to bump up the injector pressures? I was thinking about attempting to change my fuel filter, as I am pretty sure that it has never been changed. Any further help would be great. And thanks again to dynotunemotoersports for there ongoing help with my issues.

spincobra03
03-27-2006, 05:56 PM
mojo call dan at pro dyno and tell him what the deal is. I'm 100% positive he can fix the problem. If you email him a print out of your dyno run he can fix it for you with a new tune. Well that is if you have an XCAL2? either way call him and hell help you a ton.

mojosvt
03-27-2006, 06:24 PM
Actually, I am heading down for a personally session with Dan on the 7th of april. The xcal2 is already in the trunk, along with the stuff for my 411 trip. Can't wait to see if dan can smooth that curve out.


I just was wondering if anybody else had seen this, and a fix for the problem..fuel filter??? injectors??? anything???

spincobra03
03-27-2006, 06:31 PM
i dont think you have enough HP to be injectors, I had the same problem running a little lean towards the end and dan went in and added some more fuel in a few spots and smoothed it out, believe me your in good hands

Pro-Dyno
03-28-2006, 07:51 PM
Dan has Nextel...I can just beep his phone with two way.

Do I need to change the alternator pulley with a 4lb lower or will I have charging problems if I don't? If I can get 475 rwhp with a tune and a 4lb lower then I'll be going that route for now till my hp hunger strikes again! :D
151*131197*23:thumbsup:

mrpork
04-10-2006, 08:58 PM
do you guys know of anyone in the rhode island area that can tune a car

cobrabitn
04-10-2006, 11:36 PM
E-mail Pat Madigan for the Rhode Island answer. pmad300hp@aol.com but I think he would recommend MPE Racing for that?? :scratch: