If the valve job on your heads is factory you shouldn't have to worry about shimming. Unless you are turning 7000 or so rpm

 

Ok cool, ill forget about that then

 

I'm sure the Borla straight pipe axle-back will gain you some power, but I'd still hold off installing it, at least until after you've eliminated PR length and possible worn/weak valve spring from the equation. This way if you do gain power from the shorter PRs and possible new valve springs, you get a more accurate estimate of what was really holding your power back.

 

Imo, If you have access to a Valve Spring Height Micrometers you can either barrow or rent I'd do so. Even if you have to buy one they only cost between$40 -$75, and the shims are fairly inexpensive to. You might find out your valve springs might not be at the recommended seat height, or they might be spot-on, but you'll never know unless you do check.
The only question is, do you prefer to guess, or know...?

 

I get what your saying, they only thing is that Im assuming the Borla's wont gain me much, not like say headers would or something. But Im trying to save myself from going to the dyno over and over cause its 75 bucks each time and ive spend enough on this project. I could have bought gears and a new nitrous kit by now lol.
Ive known all along that my pushrods were on the longer side so there isnt a question on that. I originally was going for more preload for quiet valvetrain but I overdid it. as of right now, the springs being worn isnt for sure but once I get them tested ill know for sure. I was only at 75% on my injectors so im pretty sure its not a fueling issue but I also purchased a Fuel pressure gauge so I can rule that out. Im really hoping its just the pushrods but It just seems like too easy of a fix and so far that hasnt been my luck

 

I think you are correct in that opening the exhaust might help some, but it isn't the root issue. the original question was - why didn't you get the power out of the cam that you expected, and I think you have what you need in this thread to answer it.

if you really want to know what it was, I would try the pushrods first, springs second, etc. if you just want to get it done in one shot, do both. if you still don't get the power, you'll have to look at the heads. your intake and headers should be flowing enough to keep the cam breathing.

 

Exactly. good thing I hate my stock mufflers anyway. Ill keep you all updated. springs will be tested this week

 

Update here.
I got my springs checked and they came out perfect in terms of the factory specs. I also checked them all for cracks or defects. At the same time I installed 7.400 pushrods instead of 7.450 so I should be around .070 preload with my ls7 lifters.

I was surprised that my valvetrain is actually quieter with the shorter PR's. The car seems to run a little stronger in the upper RPM so I really hope that this fixes my issue.
Next im going to install a cutout or those borla straight pipes and then its back to the dyno.. Even if I could get around 380whp id be happy, atleast Id be on par with other cars that run stock heads and similar setups. Then id know my heads are the next upgrade. I also installed a fuel pressure gauge to rule that out when it comes time to dyno


Anyone that has a cutout, did you gain anything? or just lose tq with the drastic decrease in backpressure

 

When do you plan on getting back to the dyno

 

I didn't install cutouts, but I did have my y-pipe come separated, which acted like a dump at the headers. Didn't notice any loss at the low end, but it felt faster at WOT.

My neighbors loved it, too, which is why I reconnected my exhaust.

 

Little update. I installed my 7.400 pushrods and the car seems to have more power throughout the rev range. hopefully its not all in my head. I ordered parts for cutouts that ill be installing on saturday. Borla straights fell through but I think ill be happier with cutouts anyway.
I had my valve springs tested and they came out perfect. full pressure on both intake and exhaust
Im starting to think that my tune could be part of the problem. When I had gripes about my dyno number the shop said 2 things. They said that 29 degrees of timing is way too much and that my BBK intake is just for looks and is no better than the LS1 intake.

Both of these statements are bullshit!!

A quick google search will tell you that numerous people are running 29 degrees at WOT and im at 27 now..

This article disproves any gripes about the BBK intake being worthless. yes a FAST is better but at my power level, this intake should flow more than enough

http://www.superchevy.com/how-to/vem...take-manifold/

These guys were able to hit 343/353 with nothing more than 1.85 rockers, CAI and an axleback. how could my fairly big cam, headers, intake and more only be worth 20hp over the car tested here.
http://www.superchevy.com/how-to/090...installed.html

Im honestly very let down by the shop that did my tuning. Everyone locally said to go to them and that they'd give me a solid tune. but for them to try and disprove every point I made when it comes to my low dyno number just pisses me off and to top it all off, they wont give me a copy of the tune file so I can get some other opinions.

After I get my exhaust done, it will be back to the dyno. Ill post numbers then

 

Where are you located? Maybe there are other shops/tuners in your area that someone could recommend.

 

There are other shops. Everyone said these guys were the best. Im sure 99% of their customers are not involved in the tuning process and dont realize how much of an effect it can have. Ive done all the work on my car myself and im not a noob when it comes to this stuff.. Im not about to spend another 400 bucks for a different shop to do the tune and register my car on their cable ect... so basically im stuck with these guys

 

One option might be to buy a copy of something like HP tuners AND tuning support from somebody like PatG. Then, you can have the software to really analyze for yourself what's going on and some expert support for a few tunes.

it would be a $700-900 investment, but you would be able to tune for yourself and just pay for dyno time, so in the long run would be cheaper.

For me to have the car dyno tuned three times, I would be at almost $1200.

 

Oh I would absolutely love to do my own tuning and while I know some stuff, I dont really trust myself with it. Unless someone can point me in the right direction of a good place to learn? any books? or instructional videos?

 

I'm having the same problem. I live near NicD, so I don't expect to be as good as him, but I've thought several times to pay him to teach me. I saw a deal on PatG's website to bundle tuning service and software purchase, and I thought about it so that I could learn, but still have a safety net.

 

5200 feet of elevation and they put 11 degrees of overlap in the cam??

Just wow....

the torque curve is expectant of the evo event of the camshaft.

 

Can you explain why overlap is bad for high altitude?

In my head I feel like I have a pretty good idea as to why but before I say anything Id like to hear your opinion