gtfoxy

I recently aquired an 04 GTO that I am getting sorted out but my plan is to turbo this one like I did my 5.3L Blazer, and every other car I have owned in the last 20yrs. if it didn't come with one, I put one on.

I did the Blazer because I like the Typhon/Cyclones of yesteryear & always wanted a V-8 turbo in a Blazer. So I found a $650 Blazer with a rod knock & the next day was prepping it for a 5.3L.

Well, that's ancient history & I am looking to move on with a Turbo Goat...

I have always been a person who has appreciated the piping simplicity & under-hood appeal of Twins. That being said I have had more single turbo set-ups than twin, so I am not really Biased. But I do like how "Twin Turbos" rolls off the tongue.

So here I am with a 04 GTO M6 that I will assume, for now, has been modded with Ported heads, LS9 cam, LS6 Intake, 92mm TB, TSP headers, ZR1 Clutch, Roller Rockers(I know it has these), etc. I was told it had a 285L/hr pump, but I wont know on a lot of this stuff til I tear into the motor. It is what it is at this point.

Looking at my logs it is reasonably healthy for a HCI LS1. It logs 43-48lb/min from 5-6500RPM Peak airflow was at 6500 @ 47.8lb/min. I was told it put down 400WHP, so with those airflows I would tend to believe it. So top-end wise it should be good for an easy-on-parts-tune of 600-650HP at around 8PSI. The max I would want to push it is 16psi, or around 800FWHP. I also would like it to be at full song (8psi) around 3500-4,000RPM.

Looking at doing the following simple supporting mods;
80lb/hr Inj.
Twin 044's w/-8 with Truck or Aftermarket rails (if needed at this power level) planning on keeping it returnless for now.

Looking at combos I see guys having good results with the s475 & S480, those just are little out of the range I want to spend, at the moment... Many seem to do OK with the On3 76/75. I am looking at used one but a 64mm exducer in a .96 A/R seems a Tad small to me for this application. They have their new 78/75 but it appears to have the same turbine wheel... My other option I have been pondering in a single is the CX 80mm GT45. It has a more substantial flowing 88.9/77.4 turbine wheel in a 1.04A/R Divided. Just not sure if this would respond in a M6 car the way I want. if it is close to a real GT4508 I would be sweeping through the meat of the high-efficiency island around 40-50lb/min & never moving far out of say 74-73% at around 63lb/min (58-63 est. @ 8psi).

In the Twin Territory I was looking at turbos in the 60-64mm range like a GT35 in T3/T4 configuration with a 61/82 Comp & 68/62 wheel in a .63- .81A/R turbine or a Straight T4 with the same size wheel in open .68's . Or I found a 64.5/73.8 Comp with a 82/61.4 Wheel in a .70 Divided.

Plans were to run dual 38mm gates on the twins & a 50mm single. Or should I go bigger?

Also, I have several 5.3's & a 4.8 laying around, for those that remember my V-16 insanity thread, so I can go with a Iron block right off the bat if I should just go that route.

What say you all?

gtfoxy

Nothing? Not even a titter? No?

Tough Sub...Ha!

Maybe this will peak some of your interests, maybe not: This is for round one testing. While tuning on this is being completed I will be preparing another engine for a tad more compression... ~14:1. & with a new fuel delivery system.

To be ran mostly on pump gas...

IronBlocked

It just looks like you've got it figured out, an iron block and a good ole spinny muffler (which you've selected pretty well) and you're good to go

gtfoxy

Well, thanks for the words of confidence. It is much appreciated.

I am hoping I was getting close on my selections here. This is my first time going big on an LS & want it to be as close to right as the budget will allow.

mkvamso

iTrader: (2)

https://ls1tech.com/forums/forced-in...win-gt35s.html

Here's my twin turbo build thread
I was happy with the results for no more than i spent on it
Made mid 700s at 17psi

Ran it up to 25ish a handful of times on the street and it didnt seem out of turbo yet

They would spool lightning fast on an ls1 but i think they would carry well still

gtfoxy

Thanks for dropping in.

I checked out your thread & will watch the vids when I get home.

Looks like the CX set-up worked well for you. I have seen those & will probably do something similar if I go the twin route ( pretty sure I will). I saw you went with the ball bearing units. Are the turbine housings .68 A/R's?

coltboostin

Twin On3 67's. stock Ls1 M6. Very happy with spool and power

https://ls1tech.com/forums/forced-in...7-turbo-s.html


To give you an idea of how it spools on the street

gtfoxy

I checked out your thread & I have some q's I didn't see answers to.

I also couldn't see your tach in the vid, but in a post you said it made full boost at 4,800rpm, correct? Is that just on the dyno or does it respond the same on the street? What A/R are the turbine housings?

It's awfully coincidental you drop in as I was actually strongly considering going 66-67mm comps, if I go twins. I have looked at both the on3 & CX 67's. CX has a billet 67 also but I was not planning on a billet. Would be nice but it adds a tad more cost than I want right now. Don't get me wrong, I know it's probably the wiser choice, I just have to stick to a budget to begin with & I may end up going the upgrade route later, & if I do I will know what the gain actually was over a standard wheel.

I'm still really up in the air on a set of 67/.68A/R P-trims vs the 80mm 77mm 1.15A/R Single. I can easily do a crossover & log header & not deal with trying to work around the A/C, but I am leary how it will respond compared to the twins. Add: I also saw they have this available in a T4 & T6 configuration. Same A/R. What is the expectation of response time between the two, if anyone can share their experiences on going from a T4 to a T6. I'm leaning toward the T4 for space considerations.

With the .68's I should see 8psi around 3,000RPM. That is where I do most of my driving & I have always enjoyed the low-end squirt of low RPM response for a daily driver.

Last turbo set-up I had would jump on the converter at 3,600 & instantly peg 7psi then a by 4,200 was at 13.5psi (a fraction of a second in real world time). If it were a manual I would expect it to "feel" a bit laggier than it was.

gtfoxy

I think I have done a 180 & decided to try an on3 78/75 .96 A/R. I could not get an answer as to what the turbine wheels actual dims are but I will measure it when I get it & post it up. The guy I talked to was super nice compared to CX that never returned an email... Too bad, so sad...

It has snowed here so I have a few things to do & a few logs to gather then tear it down & find out my specifics & start building a turbo system. I'm getting pumped to see what this baby will do.

coltboostin

Sorry I am seeing this late! If you watch the video, the tach is directly behind the steering wheel, and the number at the 12 o’clock position is 50k (5000 rpm) You can see even in 1st gear (worst case) its at 10psi well before 5k. Also this is a VDO tach that is famously slow and inaccurate on stock LS1 ecu drivers. In my case, its much slower than an Autometer I tested it against, and rear 300rpm lower than reality. So full boost in 4th comes around 4200 on the tach-so figure 45-4600 in reality.

Yes, this would be substantially better with an Auto, and a better gear. Remember this is with a 4.10 rear.

Glad you went with On3. you won’t be disappointed!

gtfoxy

Thanks again for sharing.

Can you perhaps take a screen shot of a log showing MAP trace vs RPM where you are pulling from say 3,000RPM?

I'd probably have gone with the CX but they didn't email me back, so too bad so sad for them.

Forcefed86

iTrader: (4)

You're wanting to make a relatively small amount of boost/HP. The .63 Gt35's would work great for your goals IMO. Smaller compressor units will spool up faster. No need for 1000+crank hp worth of 67mm turbo to run 8lbs (or 16 occasionally) on a fun little street toy. I go with a pair of the cheapo GT35's like so...

http://www.ebay.com/itm/GT3582-GT358...lVeoPn&vxp=mtr


Pump/race gas or E85?

Twin 044's seems like overkill for pump. I see zero reason not to run a single 450 walbro in tank on the OEM fuel system. Denmah does this with great success, doesn't even use a 1:1 FPR at over 700whp. 450 is a great pump, very reasonably priced, and quiet.

Good luck!

gtfoxy

I totally agree with you as I was looking at those 61mm's to begin with. They would certainly spool very well. I was more concerned with pushing them too hard later & just making hot air. While I don't have an exact compressor map I have researched similar turbos & where in the maps I would more than likely land. 4Jenna is running twin 67's & is making on a carmed 6.0 about what I was looking to do. That's why I was thinking 66-67mm & have room to grow later.

All that kind of went out the window when I decided I did not want to mess with the A/C or having a time trying to work around it. There's more room on the drivers side to mount a nice sized unit that would save me time & money by not having to either buy headers or make them. Truck manifold on the pass. side feeding a log on the drivers will be easier & cheaper & should support my power goals.

I am conservatively realistic when I estimate power. That way I am always pleased when I make a tad more than expected & not bummed when I dont.

It's going to be a DD that I take to the track maybe once a year, so I really would like to keep it. We now have 1/8mile radar runs once a year at the local airport so I will probably do that for the fun of it. I am just too busy during the nicer months & the closest track is 3hrs away in any direction. When I lived close to a track & had weekends off I went every week. I'm not trying to set records or boast track times, I just want, like you said, a fun street toy that makes a good amount of power.

I will run it primarily on pump. This is phase one. Phase two will be more of a comparison test on things I am working on. That's when the compression will get cranked up & things will start to get real interesting. No more manifold pressure, just quite a bit more power & efficiency.

I'll consider the single in-tank pump, thanks!