Ok, so I went out and bought an lq4 out of an 02 gmc sierra.
I'm swapping this into my 68 firebird. My goals are to run the stock bottom end with twin turbos for now and see how far I can push it. I'd like to see 500ish rwhp on pump gas and come in around 700rwhp on pump w/ meth injection. I know, ticking time bomb but it's my toy car and I want to see how far I can go for the smallest amount, and I really like the idea of going to the junk yard and picking up my new race motor for under a grand whenever it pops. I'm a little sour after fragging my built ($10g ) pontiac 455 in less than 5,000 miles lol.

Anyhow, here's my plan. Swap in the lq4, add a stock ls1 intake, most likely flipped cts-v manifolds, and do a budget turbo setup. The rest of the exhaust is already 3 1/2" duals all the way out the back.
Here's my questions, I'm thinking used ls6 cam while I'm at it? Is it worth it in terms of power increase or am I only going to gain 15 or 20 horse with it?

Not sure if I'm going to do it now or over the winter but I was thinking of adding a set of l92 heads. would they be worth the expense or would the gain be too small to justify the extra grand?

Lastly, going to go ebay front mount, whatever the largest I can find to fit. Then I'm up in the air on turbo selection. Possibly a pair of stock grand national turbos to be super budget? Or, what would you guys reccomend? Looking for streetable, not a supra like power curve. I'm used to big cube torque and don't mind giving up some top end to get the kick in early. I'm also not against spending in the low 1g area for turbos/wastegates if it gets me what I want. Possibly leaning towards MP 60-1's? Already turbo'd a friends carb'd 383ci third gen with a pair of those and was very pleased with the results. But, if there's a more budget friendly way I'm all ears.

My fuel system is already up to the task, just need to swap to an efi regulator and the rest of the chassis is more than ready. Right now I'm running a built 2004r but as soon as I sell it or find the right deal I'll be going t56.

So there it is, critique away. I want to hear what you guys think and if you have any other input I'm all ears.

 

LS6 cam and quality aftermarket valve springs/pushrods will be a great budget addition to the LQ4. Well worth the effort of installing them.

 

Since you're on a budget, I would just got with one larger turbo. Something along the lines of a Master Power T70.

 

I know a single would be cheaper but I'm concerned with keeping the fastest spool up I can while still hitting my numbers, hence my wanting to go two smaller turbos. I am doing a budget build but I'm willing to spend a little extra to achieve what I'm looking for where I need to.

 

No other suggestions on turbos? Or opinions on l92 head swap?
Figured I'd be swamped with opinions by now...

 

First off, do not waste money on a l92 swap. You will not need it to make the hp you want and also the heads have less deck then even the stock 317's. A Ls6 cam and dual springs will work well. You can keep the truck intake as it works just fine to 1000hp. I would go with a single turbo if you want to keep costs down. Look for my thread with the 825whp GTO in this section, we did this with a stock lq9 long block from the junk yard with just a ls6 cam and dual springs. We used a s374 BEP turbo at 19psi with race fuel and meth.

 

My only concern with not keeping the truck intake is I was told it won't clear the first gen f body hood. I would imagine it would make for slightly better low end power anyhow if I could fit it.
As for the s374 BEP turbo, how are spool times with that unit on the street under normal driving? I'm leaning towards twins cause I'm not a fan of big turbo lag.

 

Believe me there is no lag to speak of, Dave says it comes on way to hard for the drag raidals anyhow lol.

 

I agree here!

 

** ebay link removed **

I was actually thinking about something along the lines of these, only maybe hunt down a set with a T4 exhaust housing? I'm a newb when it comes to AR ratios and compressor maps and stuff. Making them fit and work is easy, making sure I have the right ones is still part of my learning curve lol

Or like I said stock grand national turbo's maybe? Internal gates would definitely help keep the budget down...

Just checked Bullseye's website on the s374 and with what they want for the turbo I'm looking to do the entire system for less. I know it's possible, we spent almost a grand less on a carb'd 383 sbc and made well over 500 on pump at the wheels.

 

Buy a dozen of those turbo's so when they malfuction you can just throw them in the garbage.

 

Having done alot of this here are my suggestions.
Used cam, Z06 is fine, a little bigger would be good too. Will pick up about 50whp with the Z06 cam at 10+psi
LS6 intake, they are alot cheaper now and well worth it for looks alone
Pushrods and a set of valvesprings. Comp 918s or another good beehive type is good enough for now, i run stock springs with .565 lift at 12-13psi still
Turbo- I HIGHLY, and again, HIGHLY suggest a BW s475 with the small 1.1A/R T6 housing and 89 trim wheel. Its $585 brand new from forced inductions>> bottom of page
http://www.forcedinductions.com/productsborgwarner.htm
and spools like mad on a 6.0L. I run the bigger wheel and 1.32 housing and have traction problems on the street, would go with the 1.10 if i did it again and may switch to it anyways next year. You will not be dissapointed i assure you, and it will be way easier to fab the system. BTW, best sound you will ever hear with these BW turbos
Run a 4" downpipe as far back as you can
Either swap to a carb blow through system(preferred) or get the 65# injectors
I run the cheap XO2 racing 60mm wastegate (ebay $150) and it works flawlessly, also their 50mm tial knockoff BOV is very nice and cheap

Any other questions ill try to answer them. I am making 525+whp at 8-9psi and i dont even have an intercooler. just make sure your tune is spot on and you wont have any issues.

 

Hmm, if I got something like the s475 would it be worth paying the extra for a t4 housing?
I'm not afraid of extra fab work by going twins, nor do I mind spending extra to have twins but everyone seems stuck on singles here? My biggest concern is lag. Around what rpm does boost come on and where are you hitting full boost? I realize that's a loaded question with a lot of variables but what are you seeing?

 

At 700whp your back pressure will get pretty high with a t4 back side on that unit with a 83mm turbine wheel(S475). It will respond well though esp. at the 500-600whp range though.

 

I agree, the T4 housing will start to limit at higher power levels. The small T6 isnt much bigger fitment wise. With my big 475 i can get 9psi on the footbrake, 3200rpm. I am into positive boost around 22-2400 driving around town. I get full 11psi around 4200. Also i am well into the 500tq area at as low as 3000rpm. I think you are worrying about the whole spoolup deal way too much. There are alot of people running the 1.1 S475 on 5.3s and they dont complain about it at all. The fact is you have a 6.0L and you are going to have so many problems getting it to hook, you will actually want some lag. I am very happy with the smooth delivery i have as its much easier to keep the tires down.

On a side note, a brand new turbo at that price leaves alot of money for a good intercooler, cam, heads, that will make up for alot more than a couple hundred RPM in spool.

 

So which housing does it come with? When I saw T4 was an extra cost option I assumed it came with a T3?
And yeah, I am kinda hung up on spool times, I'm coming from big cube torque. However judging by your numbers you're around where my 455 was anyhow. I can deal with what you describe no problem. Now you're making it really hard for me to find a good argument for twins besides "it looks cooler" lol.
As far as hooking my car is very well set up and had no issues hooking 500ft lbs. off the line as it sat so I shouldn't have any issues there.
So with that turbo do I have a good shot at making 700rwhp with careful tuning and meth? What about my 500rwhp on pump? Or, should I go slightly larger from that same list and give up a little more spool time?

And is that all you have done to your motor is a cam and springs? All the rest stock? Sounds like you pretty much have what I am looking for.

 

I dont even have springs, just a cam and pushrods, i dont rev it much past 6k as the valves float, lol. The turbo comes with a T6 1.10 housing. IMHO T6 is the only way to go on a 350+ cube motor. I was out tonight with it playing, I switched to E85 yesterday and was getting the tune going. From a dead stop, from idle i get 9-10psi as early as 3600 with the 1.32 a/r housing. also i see that doing this i am over 500ft-lbs as early as 2800rpm, and it never goes below 500ft-lbs, ending at about 515 at 6200rpm. HP gets to the mid 400s around 3k, and gets mid 500s about 4800. I pass 600hp about 5600 with 10-11psi and 18 degrees timing. This is all at the crank BTW and not terribly accurate, but a good reference and tuning tool as i use it. I have a very good setup and can hook this on my street tires to the tune of 12.0s easy enough, thats on a M+S rated tire @3800lbs BTW. 500whp will be no problem at all on pump gas if you run an intercooler, and you should be able to get closer to 550whp. With intercooler and methanol/pump on a completely stock motor with that turbo, i would bet on mid 600swhp on about 15psi quite easily. I personally wouldnt go higher without some upgraded parts though. One thing that i highly suggest is a 160* thermostat, and take the rubber seal off it for more flow. I can pick up .2-.3 just by letting it cool an extra 10-15 min at the track. Keep askign the questions i like to help!
Gary


EDIT: BTW, to put this in perspective, my brother has a 83 cutlass with a 455 olds. Edelbrock heads, huge cam, 2" headers built trans, 9" the whole deal. Basically the exact same car, but his is about 250lbs lighter than mine. This car moves out very good to the tune of high 11s@115 or so on slicks. He drove my car around one day and he said the amount of TQ i had compared to his was unreal. We even lined em up at the strip and he gets me for about the first 100-150', after which i can put major lengths on him. Also i drove my car the 65miles to the track, cruised for 2 hours, and 80 miles back home. Ended up about 8 tenths faster than him, he was a bit upset but was glad to see me do it. If i remember right he did 470whp and 450wtq a few years ago but hasnt touched it since.

 

So, if I go big single is a 4" exhaust enough or will it begin to limit power?
I have a 3 1/2" dual with an x pipe right now. I guess I could go from the turbo as a single to the where the x is and then basically turn that into a y and use my existing back half. Would it be worth my while to squeeze in a 4 1/2" or a 5" pipe off the turbo to my y?
Limiting total power with too small a pipe was another of my concerns with going single over twins.

Grr, from everything else you're saying it sounds like you basically are putting down the numbers and overall driveability I'm looking for. You pretty much just outlined all my goals. I'd like my 1/4 times to be dipping tens but my car also weighs 600 lbs. less than yours (lots of fiberglass ) and low 11's will realistically keep me fairly happy as I'm basically turning it from a track biased car to a stupid fun street toy.

 

As far as blow off valve is this the one you were referring to?
** ebay link removed **

And I cant seem to find the XO2 racing wastegate but I found these:
** ebay link removed **

Would those work? Anything else I should lean towards? I don't mind spending more if it's much better/more reliable but I don't want to overspend if I don't have to.

 

These are the wastegates

** ebay link removed **

They do work well, i have a 60mm, any of them is big enough. Be advised though they have really crappy v-bands and dont seal up perfectly, but that doesnt bother me too much. Do not buy SSautochrome, bad products.
for the BOV i would get a Tial, Turbosmart, or OBX ($100 cheaper) 50mm. here is a good one

** ebay link removed **

For exhaust a single 4" is enough for 1000whp. I think you have a good idea of running it to your X pipe and using that, should sound nice and have no restriction. I run a single 4" front to back. No need to go 5" unless you just have the room, Definately be generous with the exhaust wrap and coatings though!
I think with the smaller turbo i recommended and a similar 3200stall or so you will be way ahead of the game. My best 60' is on the 11.42@119 pass in my sig, only a 1.76. If i can get a 1.55 it would put me at a 11.0 and i was also going into a 45mph headwind. I plan on doing well into the 10s@125 or so on the 17th so we'll see. I think i picked up around 70hp with the E85 so it shouldnt be a problem.
Gary