Although im no expert on boost yet, it sure does seem that your turbos are too big, tune probably whacked, mig welding cast is a no no probably bleeding boost off too, wrong valve springs, You havent listened to advice of those in the know for this entire build so why are you surprised now that it doesnt make any power?

Get it on a dyno with a reputable tuner/shop and post the graph and we can help from there. If your set on those big screws add some spray

^ sounds like what you asked for

 

If they are real T70s with 70mm inducers you have somewhere near 1400hp worth of turbos on a car that's making what, 400 hp? I think you have both way too much turbo for a low power engine and way to much rear gear for a turbo car. I don't know what the ebay turbos spec out at.

Maybe try just one T70? Even at the same 10psi but twice the mass flow you will be up in a much more efficient range on the compressor map.

 

My goal was to be where the BBC was with better gas milage. The MIG welded cast hs no leaks, I painted with ceramic paint and there are no black spots on the welds. As for the advice of others, I have listened everything everyone has said very carefully and weighed my options with the amount of money that I have. I bought the turbos before I had joined the forum and decided on those after reading Hot Rod articles that didn't give quite all the facts. I put the 3.08s in the car and the thing ran worse than it does now, so I put the 4.10s back in. I don't have the money to buy a bunch of parts right now, this whole build has been done by selling the old engine, side work, scrapping metal, and selling used tires. I have been working on this for well over a year and I will get it right, it will just take time. Thanks for your input.

 

Ahhhh yes hot rod articles.... Well they need to be taken with a grain of salt and that set up had ported heads, an experienced tuner, and a well matched cam and springs.

What you have to understand is matching parts are CRUCIAL to getting any set up to work. My attitude towards boost is simple; Your merely adding atmospheric weight to the engine, the characteristics of the engine do not change by doing so. Considering this I feel its best to build a naturally aspirated combination that works well for your style, THEN add boost to match that combos torque curve. So in your case you need to match the turbos spool, and peak, along with the engines NA curve or it will be under achieving, which is what you have here, BIG time its a slug no doubt.

So you have options. Easiest would probably consult a shop that specializes in boost and get a cam and spring package that will compliment those turbos or at the very least seek out a well respected tuner who handles boosted LS engines and follow his advice.

Boosted builds are typically NOT CHEAP AT ALL especially when it comes to shake downs and retunes and whatnot so considering how far you have come, your going to need to go further to get this thing working right.

Good luck

 

Don't get discouraged 99VetteFRC. I had a "Professional" shop do my work for me and I've been fixing their work since I got it back. I just now (9 months later) got it to a point where all boost leaks are sealed (spools great now!). Again, check all exhaust connections (with the car running) to make sure all the air is going through the turbos, especially the wastegate gasket, that's where I had a BIG leak. Check all the charge piping as well. Other than upgrading the cam, I think you already have a decent combination for the size motor you have. You don't need some custom grind cam spec'd from a specialty shop for the level of performance you're at. GIVEN the combo, something is not right with it. As described, you should be getting better boost, faster with what you've described that you have.

As far as boosted builds not being cheap at all, I think denmah would disagree.

Hang in there. When you find the problem, you're going to be like, "Are you kidding me! THAT is why my setup wasn't working?" True Story!

 

Buying a $20k platform that has 90% of what you need is cheap alright...

Not to mention the HUGE tuning hurdles they had with the 58x ecm and the two years of work and effort it took to sort it out. All thats "cheap" right? Not to mention the engien they grenaded sorting through it.... swapping it out etc.

I love that build btw. One of my favorites but it wasnt "Cheap"

 

I'm the one who street tuned the car for him, and I can tell you the tune is not the problem... The problem is that the turbo's are just plain too much for that little engine. By the time it is making much boost, the 1/4 mile is nearly gone! There are a couple options - get smaller turbo's (or go to a single) - get a bigger engine - get a better cam/spring package for the current engine (and that is only gonna help so much)...

Think about it - 6# of boost (coming in very late) on a bone stock truck motor, in a car that weighs about as much as a truck - it is right where I would expect it to be for that combo...

 

Actually, I had another thought... you are set on the look of twins... is there any way you could run a crossunder pipe from one side to the other and turn one of them into a dummy - blank everything off discretely and make only one functional (keep the other for looks)... just a thought.

 

Yup. ONE of those turbos would wake that thing right up. As for the Denmah comments earlier I had no idea of what he had done with the latest jy builds, impressive on a budget for sure but single and small snail.

It is builds like this that make me hate on HR articles though. I did search that article out again and they had TEA ( one of the absolute BEST ) ported heads on that 4.8 build that got everyone horny for these things and quite a healthy cam as well, plus as mentioned its sitting on an engine dyno not bolted into a tank like a Chevelle.

Stuff a 220 range cam in that thing or similar with one of those turbos and some GOOD valve springs PAC beehives whatever their top ones are nowadays I dont know the pn off hand with some hardened pushrods and this sucker will fly. Sell the other turbo off to pay for the parts and do the hotside re-work and voila. Stay in budget and my guess would be 500 plus whp at minimum. I didnt re-read this thread but the hotside should be 2.5" or even 2 1/4" into a single 3 just before the turbine that outta get it spooling fast.

Plus it will have a nice lope at idle.

As for the "dummy" twin look? Not a fan.... Why front what your not? Nothing lamer imo

 

I ordered 2 turbos last week. Swapped the one I recieved already and it dose make a ig differance. It spools faster now and is skating the tires around 4k rpm now. Waiting for the 2nd turbo to show up then that one will go on and that should fix the problem. Also gonna ask the wife for an LS6 cam for Christmas.

Was thinking of selling the twin setup and building a single setup with either the t60 I have or one of the t70s I'm taking off the car. I may also build a single setup to sell, I have a set of f-body manifolds I may try to use for the single setup. We will see.

 

What turbos did you order? (Getting confused with all these turbos in the thread... lol )

 

Glad to hear that thing is coming around for you. Ask the wife for a custom turbo cam instead of the ls6.

 

Bought 2 of these.

http://www.ebay.com/itm/110768842608...84.m1439.l2649

 

Heard good things about the ls6 cam and I already have the springs in the engine. If I go custom then the wife won't be able to afford all the stuff to go along with it.

 

Make that two of us. Glad shes starting to sizzle the bacon now

 

Sweet! I can't wait to see what results you get with these. I have a feeling they will spool up real fast. Hope they last up top. Keep us posted. Would LOVE to hear good news from such an affordable set of turbos.

I'm looking at doing something similar with a pair of small ebay turbos on a 72 Camaro with a 2005 4.8L motor. (Super T70 T3 V-band Turbo) which are really like 56 mm turbos.

Keep us posted.

 

I'm pretty sure the turbos you just described are the ones I bought first time. Way to big, just won't spool up. If you are set on those I will sell you mine for $300 for the pair, they barely have 1000mi on them.

 

May take you up on that (well, I already have one of them... bought a packaged deal with intercooler, etc a while back... never used it on my 2002 Camaro, went with an On3 Perf 76mm instead). Hang on to them for now until you get the new ones on and get some test time. You may find out that it was not the turbos and want to put the 70's back on.

 

Just getting caught up brother. Sorry to see the Ebay T70's did not work out for you. We have a similar setup but I have a 5.3 with an LS6 cam. Either way after reading your plight it just reconfirms what I had already planned to do. Toss the T70's on my C10 with the 6.0 and run a nice T4 flanged single turbo on the 5.3 in the LeMans. I may need some of the parts you can't reuse on your single turbo build. Just pm me what that may be and I can put some broccoli in your pocket to complete your build.

 

The new turbos actually bolt on where the t70s were. All I had to do was buy the flat 5bolt flange and vband rings and weld them together. Just wish the 2nd one would show up.