Finally...twin turbos for my LFX

[alice]

Jantzen, Everything looks like it is coming together really nice for your project, quite impressed. If I may have some input here and I'm not trying to tell you what to do on your project but I would like to suggest this, possibly for down the road. In my 45 years of building and racing pro-street cars, most of all were FI, I found out several things I would like to share with you. Much of it, on the smaller displacement, FI engines, including the 5th Gen Camaro. When reducing CR on an FI engine in order to increase boost pressures, you certainly gain a bunch on the mid to top end performance, no question about it. But, the low end, non-boosted mode suffers and sometimes significantly. Now, the following statements I am applying to the smaller displacement FI engines because larger engines always tend to have plenty of low end torque, even when lowering compression ratio.

Here is what I have learned on smaller FI engines and applies to the DI Camaro engine. You will find that just 1 point in lowering CR in you engine will be very noticeable in your low end power, and it will take a tad bit more time to spool up turbos as well, though that is insignificant as compared to low end torque loss. This is an obstacle you will want to overcome once your project is up and running. I'm sure you will notice the launch difference. Throttle response suffers a bit, as well.

With that being said, it is my experience to overcome these issues in order to gain back what I would have lost in lowering compression. The approaches I have taken is, as follows; first, higher stall torque converter, (which you have already done) and second and a really important one is rear end gearing. (further torque multiplication)

These little 3.6's, especially when turbocharged, love higher stall and higher numerical gearing. Brings back the losses and even adds a whole bunch low end and throttle response depending on your choices in numbers. I believe that your rear end gearing screams higher numerical ratios, given your particular build specs and the vehicle. I would suggest a minimum ratio of upper 3's to mid 4's. You will gain much more low end then you took out and you will be amazed at the hole shot performance. Makes a little motor perform big! With the .67 OD in the tranny, you will still be able to cruise at freeway speed easily and you will be surprised how little you mileage will suffer.

I have changed gears in my 2010 LLT Limited Edition Twin Turbo 4 times, increasing ratio each time and realizing HUGE gains in low end performance that matches the top end performance. If you do the math with varying rear gear numbers you will find you can run pretty tall gears and still be extremely streetable. My little 3.6 with 4.88 gears will annihilate SS's off the line. It really is pretty funny. I still, only turn 2625 RPM at 70 and 2250 RPM at 60, still real easy RPM for a street machine and I only lost 2.5 MPG at 60 MPH!! Getting 25+ MPG. Now, I'm not suggesting this tall of gear for your project because I was forced to purchase a Hammerhead differential for added strength and gearing choices but if I were you, I would consider taller gears for sure. When you get your project completed, you will see what I mean about the low end issue. I'm sure you will have a great performer no matter what you choose to do.
I will be following your build, good luck!

[ghosted]

Originally Posted by JantzenOKC

What could cause you to need dished pistons? I lowered my compression all the way down to 10.5 and still running a domed piston.

Well, what I should have said was that my plan leaves my open to the possibility that I may need dishes pistons, not that I'm planning to use them already. I'll send you a PM in a bit.

[JantzenOKC]

Originally Posted by alice

With that being said, it is my experience to overcome these issues in order to gain back what I would have lost in lowering compression. The approaches I have taken is, as follows; first, higher stall torque converter, (which you have already done) and second and a really important one is rear end gearing. (further torque multiplication)

These little 3.6's, especially when turbocharged, love higher stall and higher numerical gearing. Brings back the losses and even adds a whole bunch low end and throttle response depending on your choices in numbers. I believe that your rear end gearing screams higher numerical ratios, given your particular build specs and the vehicle. I would suggest a minimum ratio of upper 3's to mid 4's. You will gain much more low end then you took out and you will be amazed at the hole shot performance. Makes a little motor perform big! With the .67 OD in the tranny, you will still be able to cruise at freeway speed easily and you will be surprised how little you mileage will suffer.

I have changed gears in my 2010 LLT Limited Edition Twin Turbo 4 times, increasing ratio each time and realizing HUGE gains in low end performance that matches the top end performance. If you do the math with varying rear gear numbers you will find you can run pretty tall gears and still be extremely streetable. My little 3.6 with 4.88 gears will annihilate SS's off the line. It really is pretty funny. I still, only turn 2625 RPM at 70 and 2250 RPM at 60, still real easy RPM for a street machine and I only lost 2.5 MPG at 60 MPH!! Getting 25+ MPG. Now, I'm not suggesting this tall of gear for your project because I was forced to purchase a Hammerhead differential for added strength and gearing choices but if I were you, I would consider taller gears for sure. When you get your project completed, you will see what I mean about the low end issue. I'm sure you will have a great performer no matter what you choose to do.
I will be following your build, good luck!

Yeah I'm prepared for a loss of power when not in boost. And I've thought a LOT about gearing. Some people think lower is better and some think higher is better. In the end I decided to get a 3.27 diff because it was a smoking deal at $280 with 9k miles and its the same ratio I was already running. I hate to be changing TOO many things at once and just be all over the place. I'll see how it goes with the compression change and convertor first, and make some 1/4 mile runs. Then I might experiment with gearing. Could always try the gm 3.91's. That's also why I decided to not do the posi mod or trutrac right now and just run the diff as is. If I want to re-gear it later it would be a good time for a truetrac and some billet caps.

[alice]

I agree with your decision. Get the project up and running, then evaluate any next moves. The car will certainly be a beast and 1/4 mile times should be impressive. Just be reasonable in expectations of ET's. I believe breaking into 10's will take some pretty tall gears along with high boost. If you can break anywhere in the mid 11s, I would be a very happy camper. And That would be worth all of your efforts and money expenditures. Again, I am so impressed with your build and I add Gretchen to that list. I followed his all out build and he certainly had my attention.

[JantzenOKC]

Originally Posted by alice

I agree with your decision. Get the project up and running, then evaluate any next moves. The car will certainly be a beast and 1/4 mile times should be impressive. Just be reasonable in expectations of ET's. I believe breaking into 10's will take some pretty tall gears along with high boost. If you can break anywhere in the mid 11s, I would be a very happy camper. And That would be worth all of your efforts and money expenditures. Again, I am so impressed with your build and I add Gretchen to that list. I followed his all out build and he certainly had my attention.

Oh I'll be happy with mid 11's, as long as I can beat Gretchens best time and be the fastest recorded V6 5th gen(as long as MagnumForce doesn't beat me to it). I dont think mid 11s will be that hard. I was running consistent 12.1's at 120mph and that was with terrible 2.0+ 60ft times. Also there at the end I think I was losing some power, probably bending rods little by little as oil was ingested until the final point of failure. The reason I think that is because the last two times I went to the track I made big weight reduction improvements but gained no E.T. The second to last time I went I had removed my passenger seat and rear seats which was about 100 lbs. That should have equated to a tenth in the 1/4 but gained nothing. Then the next time out I had my new TSW Nurburgring wheels on which saved over 7lbs weight on EACH wheel, so that was 30lbs of rotational weight which should be similar to removing about 180lbs from the vehicle. But yet again NO gain in E.T. with the same weather and DA at the track. I was also seeing my AFR going more rich than in the past which I didn't understand at the time but now it makes sense.

I'm trying real hard not to do ricer math but I feel like with just keeping everything the same but with a fresh motor(without bent rods) I should be running 11.8-11.9. Then add all my current upgrades. If this convertor and drag radials can get my 60ft down to 1.7-1.8 then mid 11's should be a piece of cake. And now I will have the ability to turn the boost up and make more power too. Then I can always play with rear gear ratios like you mentioned.

I'm exited!!

Edit: and if I ever did run a 10.99 it woudnt be consistently but some kind of hero run. I don't think the trans could take many passes like that lol.

[JantzenOKC]

Finally have all my stuff at the machine shop. But not the one I was planning on though. The guy that was supposed to be doing it quoted me a time frame of 12 weeks before he could touch it. I about fell out of my chair lol especially since before Christmas he said two weeks. Obviously that wasn't going to work so I ended up going to Boyd's Racing Engines in Norman. I went and talked to them about it and they were into it, they also gave me a tour of the shop which was very impressive. Ended up leaving everything there and I'm also going to let them assemble the short block. It'll be worth it for piece of mind as they can check and verify everything much better than I can. Plus if I do the assembly I would have to buy a rod bolt stretch gauge and a ring filer and that would probably be a couple hundred bucks

[derek1387]

So Jantzen, my plan was to be boosted by the end of the year....and my wife put a veto on that till we move into a new home.

So, that being said, what things would you wish you would have done first before going boosted? Things that I can work on doing now, gathering parts, installing this or that..while I am waiting for the OK?

I just finished the 1LE kit and Toe Rod install, and just got the car out after the long winter. So I am back in the "throw money at the car" mind set.

Thanks! And love following your build!

[JantzenOKC]

Originally Posted by derek1387

So Jantzen, my plan was to be boosted by the end of the year....and my wife put a veto on that till we move into a new home.

So, that being said, what things would you wish you would have done first before going boosted? Things that I can work on doing now, gathering parts, installing this or that..while I am waiting for the OK?

I just finished the 1LE kit and Toe Rod install, and just got the car out after the long winter. So I am back in the "throw money at the car" mind set.

Thanks! And love following your build!

There really isn't much you need with the kit. It's pretty solid as is. Maybe a boost gauge and AFR gauge. I bought the AEM tru-boost boost controller because it comes with a gauge that doubles as the controller which is nice. And you probably dont want to run the v6 trash can mufflers as they are pretty restrictive, but if your buying a turbo kit I would imagine you would already have exhaust.

[JantzenOKC]

Just ordered a full set of OE rod bearings and main bearings from the dealer. Surprisingly they aren't that expensive. $8 for each 2 piece rod bearing kit, and $12 for each 2 piece main bearing kit... So under $100 for ALL the bearings. Mine looked ok but it's cheap insurance I think. And head gaskets are like $13 each.

[JantzenOKC]

Rod & main bearings

[JantzenOKC]

Tires made it in.

[Twin Town Terror]

Originally Posted by JantzenOKC

Tires made it in.

Ooh you went big. Mine showed up today too!



275/50/17

[djcolopi]

Originally Posted by Twin Town Terror

Ooh you went big. Mine showed up today too!



275/50/17

come on guys you can go bigger lol

315/40/18

[JantzenOKC]

Originally Posted by Twin Town Terror

Ooh you went big. Mine showed up today too!

Nice!

305 is probably a little overkill but oh well. They feel so soft though, I can't wait to hook these things.