Suns_PSD

* see final dyno printouts below*

Hey guys. I wanted to use this post to document the results of this (the final) round of mods to my 2008 Z51 LS3 M6 in the hopes that others can gain some knowledge, as I have gained much from this forum.

Here are the mods that my car started with as I bought it already with some nice mods.

My car already has a Vararam intake, LS7 manifolds, a baby cam 219/ 231, a 10% under-drive pulley, .040" Cometic headgaskets, roller rockers, Ti retainers, and a tune for 93 Octane fuel. The car runs great as far as I'm concerned but I was looking for a bit more.

The previous owner of my car (forum member 'Gotcha') had shared with me these dyno graphs that showed the car stock, and mostly as it sat when I received it. Basically it showed a peak 78.7 rwhp gain with nice solid gains everywhere over stock.



The above dyno chart indicated a very solid improvement in how my car runs over and above stock. Afterwards the previous owner had tweaked the tuning for a bit better performance but never redynoed the car so maybe it had a couple of more hp.

I bought the car in IL and brought it down to TX for track days and general fun about 5 months ago. Once I added Toyo R888s the car went from feeling like a beast to a pussycat so the desire for more power kicked in. Unfortunately all of the cost effective mods had been done and I didn't want to spend a fortune. I was trying to pick the most cost effective NA mods and also trying to consolidate some tuning and install costs to save a bit.

I spoke to a handful of people and met some great guys along the way, a couple of them in the end I trusted their work and tuning but they were not able to quite offer the entire package that I desired. It wasn't about price and in the end I didn't chose the least expensive. I felt like quite the jerk for not using 2 vendors I had spoken to several times each. If you are reading guys, sorry.

I settled on really just 3 mods that I felt would give me the best bang for the buck and remain within budget. Headers, CNC OEM heads, and a Flex-Fuel conversion. I also feel that some improvement can be had in the tune. The old tune had perfect manners, but the car (see dyno charts) was also very flat up top and that annoyed me. MPG was also quite poor. I felt that these aspects might be improved with a cleaner tune. Because I already had LS7 manifolds with a Dr. Gas X Pipe, and bumped compression heads, I will not see the gains others see from these exact same mods unfortunately.

Also I have what can only be called a baby-cam and I will make less peak power and maybe have less synergy with my other free flowing mods. But $ was running out and cams are apparently a mod that the bigger you go, the trade offs become greater. Drivability and valve spring life are big concerns of mine as I plan to tour with my lovely wife with this car someday with the top off (the car, not the wife).

I am going to add to the cam discussion that I spent a good bit of time studying this article from Super Chevy where they compared many cams.

http://www.superchevy.com/how-to/eng...ft-comparison/

One thing I realized is that the 2 small cams that were closest in size to my specs, actually made more power than even the most aggressive cams up to about 6K rpm! And after that the more aggressive cams would only make 13-22 more hp tops. If I was buying a new cam for some reason, I'd go slightly bigger, but this one was close enough to give me good power under the curve (and it was already in the engine!) Also, small cams have more dynamic compression, and that means E85 will be more effective as a power adder.

1) After a lot of going back and forth I settled on new Kooks 1 7/8" headers from Maryland Speed. They weren't cheap, but the quality is very very good. The headers arrived ceramic coated inside and out, with cats, merge spikes, ball and seat mounting, with a substantial SS hardware kit, extenders, OEM gaskets, etc... Once I added all that in, I felt like I got pretty much the top product in this category for a small amount over what the Chinese headers run once you add all the hardware in and I'd make the exact same purchase again. I included photos of what I considered to be the important stuff.










The used LS7 manifolds are for sell here btw:

https://www.corvetteforum.com/forums...ets-350-a.html

2) For the heads I felt most comfortable with CNC ported heads from Late Model Engine in Houston. When I spoke to Bryan I felt like they clearly articulated what about there work was different and I knew just enough that the points they made, were exactly what I needed to hear. It was also a benefit that they had core heads in stock and could began the work right away and could effectively reduce my down time.




3) I encountered the guys that are doing my install, tuning, and fuel system mods by chance having contacted them with the intention of just purchasing Flex-fuel conversion parts. Some of you guys might have heard of Dave Steck who puts together all the Flex-fuel kits that everyone uses. The previous vendor I had spoken with was clearly not as knowledgeable about the Flex-Fuel set up I wanted. Pricing and parts suggestions were all over the place. I sort of had a $/ hp I was willing to spend for this mod so I needed clarity on this topic and I sure got it from Dave. The dude quickly told me what I needed and added in some items others had not suggested (an E85 specific filter and a % Ethanol gauge) and had some important suggestions that only come about with massive experience. It didn't hurt that it flat cost less money for that portion (the Flex-Fuel conversion) of the build from Dave, while utilizing better parts. After looking at my fuel system the guys at Dedicated didn't really approve of the in series routing of my fuel system (modified from stock by original owner) so they are going to convert that to a parallel system. This is the Flex-fuel sensor:



Here is a photo of the Ethanol Display Sensor mounted in the center console. (ignore the random junk in my center console, I have a lot going on in there unrelated to the new Ethanol display)






I was tickled when I realized that they had a new shop very close to my home, just up in Pflugerville, TX so I went to check it out. The guys (Andrew, Matt, and Dave are my contacts) at Dedicated Motorsports had a very clean large shop, and some serious equipment (5 axis lathes, 3D printers, hub 4 wheel dyno, several lifts) and some very expensive fast cars in their possession. It seems they specialize in GTRs but I was relieved to find the parking lot full of LS engine GM products driven mostly by the owners. After some time touring the shop, I knew I had found my guys. Their professionalism was notable. Everything was very clean, I instantly received a computer generated quote laying out exactly what I would be getting for my money. That was important to me. They set me up on a password protected website where I could get all updates on my build with photos, videos, and notes. When I dropped my car off they even checked it in, verified any preexisting damage with photos, and cataloged my parts, all online with a link they sent me. I thought that was professional and helps remove any uncertainty. This is one of about 8 photos they took when they checked my car in.




So my car is now at Dedicated Motorsports getting disassembled and they have gotten started. I told them no rush but they seem to think it will be completed early next week.

Dedicated Motorsports did begin by dynoing my car as it sits. According to them, it's a strong one.

I don't love the way their dyno chart is formatted. The numbers my car put out were very similar to what it put out on the previous dyno for the previous owner. Here is the dyno chart from Dedicated.




Once the car is completed I am to get a graph as the car as it started, overlay a graph with the car tuned for the new hard parts but on 93 octane (or E-10!), and a final number for the tune on E-85. The below photo is just a photo of my car with the heads pulled. Dedicated also took it upon themselves to double check the cam, lifters, and a few other small things to prepare for assembly and double check for wear. Dedicated already 2 day aired some Cometics in and they might be replacing my pushrods as well. They will just measure and decide from there.




I'm going to give approximate costs cause I know people are going to ask the costs. Your deal might be better and these are just approximates with shipping and taxes. Catted coated headers about $1,700. CNCed heads with new springs about $2,000, Flex fuel conversion all labor and tuning about $3200. Misc. spark plugs, oil change, possibly shorter pushrods, etc... about $600.

The engine is put back together and the Flex-Fuel sensor is installed and the fuel system mods are added.




I'll likely have dyno results late Friday, 1/ 29/16.

Here is the short version but I'll post dyno graphs as soon as I get them.
My car was making 455 hp/ 412 tq when it arrived. With the addition of headers and the built heads and proper tuning it made 482hp/ 436tq. That's a 27hp/ 24 tq gain for those parts. My small cam reduced the power potential of these parts. On E-70 (anything greater than E-70 gets the full timing) resulted in 499 hp/ 448 tq, another 17 hp/ 12 tq gain for the Flexfuel conversion. I'm told the gains under the curve are more impressive than the gains at peak, but I haven't seen the dyno graphs yet, or driven the car, to comment.

One interesting thing I considered is that the car is making 35% more rwhp than it made stock. It also has about 60 more rwhp than a stock C6Z, and about 80 more rwhp than a stock C7, and I have much shorter gearing to boot. Those were both other cars I was close to buying.

Picture on the dyno:




The midrange power gains were massive. A function of my small cam no doubt.

Just heads and headers and a fresh tune. I am left once again with the opinion that my LS7 manifolds with Dr. Gas X pipe made within 5-10 hp of the full Kooks system (sorry Joe!). BTW those parts are now for sell!




Gains just from E-70 which puts me at full timing advance:






Total gains:





When I first heard the numbers I was a bit disappointed given the money spent, but after seeing the torque curve and midrange power and thinking about how much time I spend there, I expect that the driving experience will exceed my expectations. A bigger cam would have complemented these parts well and would have given me 520+ imo. But I also have to remember that I have a cam that drives 99% like stock, I have cats, and I have a 500 rwhp car with a massively wide powerband. That's pretty impressive.

The other thing I've really noticed looking at the new powerband is that at redline my gains are actually 53 hp/ 36 tq as stock the car fell off after 6100 rpms. That will help at the track for sure and represents a large difference in my book.

sevinn

What did the previous owner do to your fuel system?

If I'm reading between the lines correctly, you're getting an entire e85 friendly fuel setup correct?

They sound like a very professional shop to do business with. Sounds like you chose well. Dave is the one that championed the way for us to even have flex fuel stuff setup in the tune at all!

Suns_PSD

SEVINN, I just noticed we have incredibly similar builds, except you have a larger cam and I have the flex-Fuel conversion. Otherwise, sure is similar.

The previous owner routed the fuel flow in one end of the passenger side fuel rail, then used a cross over to the other cylinder bank fuel rail that then dead headed. The concern is that 7 injectors have already gotten their fuel before that fuel gets all the way around there to that last injector and you don't want an injector sucking hind tit.

So the fuel supply with have a Y where the ethanol composition sensor will reside, then feed each bank equally.

The entire fuel system does not have to be rebuilt to run Ethanol, not at my expected hp level anyways.

At the rate they are completing the work, I'd expect results later this week in all likelyhood.

sevinn

Thanks for the explanation. Sounds like the way most aftermarket rails are installed with the stock returnless setup, I just wasn't sure before.

Can't wait to see your results.

GS_DAN

Solid build man. Looking forward to the gains with the Heads, headers, and e85.

What injectors did you end up going with? Staying with the stock fuel pump?

Thanks,

Suns_PSD

I think I chose quality parts, but I have to be careful about thinking I will gain as much as others since my baseline dyno included some mods to the exhaust system and heads already.

Dave Steck speced the injectors. I learned a few things. Mainly that you need to be careful with aftermarket injectors, as they have problems with matching that often effects tuning. So much that I was told they would not tune my car unless it had ID, or OEM injectors in it. The injectors he chose were some OEM injectors out of a Flex Fuel GM engine. They cost way less than ID's, they are of the highest standards, and they are enough injector for a max of about 550 rwhp on E85. So they were a good fit for my build. The intention is to use the OEM fuel pump and it should be fine. But once tuning begins, they could always discover that I have a weak pump and that could change, which would not be pleasant for me. They are also installing an E85 specific filter post fuel tank per Dedicated's recommendations. Something about the solvency of the E85 possibly sending mess in to my new injectors.

emoFTW

In for results

Suns_PSD

Results in post #1.

Wallacefl

Please give us some further specs on the cam including the manufacturer.

timd38

Very nice! We have the same machined alternator bracket! Not many of the around.

Joe_G

Great results! Nice write up too.

How do you figure you only got 5-10 hp from headers?

In my experience you got most of your gain under the curve from the headers, the ported heads will only come into play above 4500 rpm.

Suns_PSD

It was speced by PatH for the previous owner. Comp Cams built it to spec. It's a 219/ 231. I can share the entire cam card if you like on Monday.

Suns_PSD

Thanks!

You make a valid point about the rpm of the heads. Based on all evidence however, I think the headers gave me less than 10 hp near peak. For instance CNC heads are good for 15-17 rwhp at peak on a stock cam. I gained peak 27 rwhp already having a cam, and adding headers + heads.
But you are right that the headers were probably good for most of those low end gains all on their own.
I pick up the car on Monday. I suspect with all of the midrange gains it's going to feel very strong in day to day driving as well as at the road race track.

emoFTW

17whp gain going to e85. That's a nice gain to me. What did it pick up in the midrange? Hard to tell with that graph. Congrats on the new power.

Suns_PSD

My E-85 gains didn't translate all the way thru the powerband as I've seen with other Flex fuel adopters. DSteck would have to explain why but if I were to guess I'd say it was because he was unable to add additional timing down low to take advantage of the Flex-Fuel. Maybe because my 93 octane tune was already maxed out on timing? HP gains started to ramp in at about 3800 rpm but tq gains were across the board right from when the dyno ran began.

At about $800 with injectors, an external filter, and a gauge inside my center console all installed, and no additional tuning costs, I felt the Flex-Fuel was a reasonable value. I suspect the gains are higher during the TX summer as I'll maintain more of my hp when IATs go way up. The fuel is across the street from my office for $1.26 as well so it's very available. Also it runs cooler at the track which could come in very handy.

I'll pick up the car today and will report back.

I also have a business trip thru East TX later this week. Lots of curvy empty roads to enjoy. I'll take the Vette and report back on mpg and overall performance.

Suns_PSD

I'm going to provide a small update. I drove the car 45 miles mostly on a toll road. It runs very well. It revs quicker but it feels just like a stock car, but way faster. There is absolutely no weirdness at all. When I close my NPP exhaust it is almost as quiet as it was before which is to say Honda Accord quiet, very quiet. It pulls like an animal everywhere, at all places. from idle on up.

With the NPP open the Kooks headers with hi-flow cats are a similar volume to my old set up (LS7 manifolds and Dr. Gas X-pipe) except there is actually no drone, where-as previously there was a lot of drone.

I got my car back with new coolant, new oil, new plugs, and new plug wires. Dedicated Motorsports dyno tuned on it 1 cold and 1 warm day and it's dialed. I'm thrilled with the service I received from the shop.

One thing I never considered even for a moment is that the Flexfuel conversion, might actually result in some minor fuel cost savings. I drove the 35 miles out there on 93 Octane with cruise on 86 mph on the toll road and the car averaged 19.8 mpg. I drove it back at the exact same 86 mph but with E-72 in the tank and averaged 17.1mpg but this time it included 3-4 full throttle runs. That is a 14% reduction in mpg. I filled the tank up near work cause it was pretty much empty and it cost less than $20, but also the fuel cost me 35% less than SuperUnleaded at pretty much the least expensive station around for SuperUnleaded. Nice benefit.

I'll update the original post with a photo of the installed Ethanol Content display which I had installed in the center console. At this point, I'm VERY pleased.

sevinn

Would it be possible to get a few close up pics of how your fuel lines are routed now? I'm going to be ordering injectors soon and have some Holley fuel rails that I want to hook up at the same time.

Joe_G

^^^ Nice report Suns, thanks for keeping us in the loop.

You realize that you'll get substantially lower MPG the more alcohol you mix in your fuel, correct? It's a cheaper fuel but the math never worked out for me with the price vs. lower MPG. The additional octane is a great advantage if the car is set up for it.

Does TX have 80 mph speed limits now? Been a while since I've been there.

sevinn

There are actually some stretches of road with an 85 mph limit. Alot of cars probably drain their fuel tanks pretty quickly on them haha

Suns_PSD

No problem.

Fuel enters the engine compartment at driver's side firewall. This is where the oem flex fuel sensor is located:




That leads to an ethanol specific fuel filter upfront next to the Vararam, we are going to relocate this to fit around the Halltech intake that is on the way:




The fuel line then leads to a 'T' at the front of the engine where there is a fuel pressure gauge, and it splits to each bank of cylinders and then dead heads at the back of the fuel rails.