VincentT

Hey everybody, I don't know for sure if this post belongs here or somewhere else (Forced Induction, maybe?), but I'm looking for advice on a project I am planning.


I’m fairly knowledgeable in the ways of good ole SBC Chevy technology, but LS engines and forced induction are fairly unexplored waters for me. As a med student, I am still very much in the research (aka “I’m way too poor for this”) stage. But I start my residency next year, so the poverty hurdle should be cleared soon. Plus, as a budding medical professional, my obsessive personality can’t help but research every possible aspect of a project before moving on it. This is why I’m posting about this without having bought any parts yet. So, if you don’t mind helping a newbie out, let me know what you think of not only my equipment choices, but of my thought process. Also, as a warning, this is rather long, so if your attention span is short, you might pass.

The car is a 2004 CTS-V. It’s got 120k on the odometer, which I know is plenty. It has been my faithful daily driver the last two years in med school, and now I’m formulating plans to make it into a toy. I’ve read plenty of advice on here saying, “Get another daily driver” and that’s what I plan to do; get a hot hatch or something. I want this to be mainly a street car that I can take to a grudge match occasionally. As such, I want to make it as bulletproof as possible. I’m thinking rear mount twin turbos for this and shooting for around 600-700 rwhp, which according to Garrett’s handy-dandy boost advisor (you work with what you’ve got, right?) means around 15psi. I say rear mount because I don’t think a traditional twin setup is feasible with the cramped engine bay of the V. I don’t plan on making this a drag strip monster, so the added lag isn't as much of an issue. I’m a patient guy, so I don’t mind waiting and taking the time to do this correctly rather than slapping a Maggie on it and making an extra 100 hp at the flywheel. I’m planning on doing the project in a certain sequence so that the car will be a reliable driver up to the point that I move on the turbos and perform the changes involved with them. I’m planning on using pump gas, and am becoming less opposed to methanol in light of that. I also want the car to be a sleeper, so I want it to look, sound, and feel as stock as it can considering what I’m doing. As a side note, I’m not going STS for two reasons: 1) I want to do a lot of fabbing myself, 2) They quoted me $11,000 just for their turbo kit.

I plan on doing the project in such a sequence that early on, it will still be a reliable driver. That way, if there is a good gap in time before I put the turbos on, I can still enjoy it. Also, the things that I’m planning to keep are just as important as the things I’m planning to change/add. So, at the end I’m going to make a list of that too.

I plan on using the sponsors on this board as much as I can for parts because I pretty much owe all that I know so far about LS engines to this board.

-Tick Level 2 T56 rebuild: I figured this would be a good option since the transmission in the car is only a couple of years old and I have treated it kindly. Apparently the upgrade will handle 700rwtq. I would go level 3, but I don’t think $500 for an extra 50-100 ft-lbs is worth it.
-Clutch: Not sure what to go with here. Centerforce 12” clutch looks promising, but I’m just not sure yet.
-Timing Set: Upgrading to double roller. Don’t know if this is worth it or not. I hear it is.
-Valve springs: I’m thinking Comp Cam double springs, but other suggestions are welcome.
-Head Gaskets: Most of what I’ve heard is “Go LS9.”, and that sounds good to me, but I don’t know if there are other options that are better or at least equivalent.
-Tuning unit: This is truly the hard part for me. I figure I will go with HPTuners early on and learn as much as I can about tuning before I actually put the turbos in.
-Head Bolts: ARP 2000
-Rear diff and axles: I think I’ll just have to bite the bullet on this one, because there aren’t a ton of options that I know of for the V1. I think I will go with Creative Steel’s 8.8 rear kit, because GForce’s kit is just too expensive at over $6,000. Plus, I doubt I need a 1,000rwhp IRS. I’ve seen some guys fab up their own braces/girdles that keep it steady when wheel hop ensues, but I don’t know if I trust that or if the diff is strong enough even if it is stable.
-Mufflers: I personally think it strange to put mufflers behind a rear mount, but I want to keep it quiet. I’ve seen the STS vid of the twin turbo V revving and laying down rubber. I don’t want my car to sound like that. I would think a muffler could flow more easily than the turbo itself anyway.
-Rotating Assembly: Eagle Forged crankshaft, Wiseco dished pistons, Eagle rods, main bearings, rod bearings. For this particular part, I could probably use some advice. Mainly because of the pistons. I’m planning on using dished pistons to drop my CR(rather than get new heads) and decrease my reliance on meth. I know that will drop my non-boost power, but how much is the question. Every plug-and-play CR/HP calculator says I'll lose about 25hp, but I doubt that translates into real life. I am planning on getting around 9:1CR (whatever dish amount that requires). I know I could drop the CR with the heads too, but I explain that later. Is that too low of a CR? Also, I thought about converting to a 383, but I’m not sure if the cost/benefit will justify that. To be honest, I haven’t investigated a 383 conversion much as far as reliability goes.
-Turbos: At this particular moment, I’m thinking Garrett GT2871R, but my thoughts change daily. I’m open to other suggestions for sure.
-Cam: Comp Cams Part No: 54-480-11. 227/223 LSA 112. Not sure what to think of this cam, but I am sure it will be much better than sticking with the stock cam.
-Intercooler: A 32 inch by 6 inch fits perfectly behind the bottom grille of a V, but I’m wondering if that would be overkill.
-Boost Controller: AEM Tru Boost
-Filters
-Tubing: I would like to fab the tubing myself. I’ll probably hit up stainless works for that.
-Fuel Pumps: Twin 255’s. Would that work?
-Fuel Injectors: 80#.
-Scavenge Oil Pump or pumps
-Gauges, Sensors, Etc.
-Methanol kit if necessary.

What I plan to keep. Feel free to critique what should stay vs. what should go.

-Block, obviously.
-Intake and throttle body
-Cats
-Heads: I plan on keeping the heads because, from what I know, the LS6 heads have good flow. I know I could get new heads to drop my CR, but I am going to need a new bottom end anyway, so why not drop CR with dished pistons?
-Peripherals(pulleys, oil pump, water pump, A/C, Power steering)
-Ignition system
-Fuel rails? Not sure about these with twin pumps and 80# injectors.
-Rockers, lifters, valves? With 120K on them, should they be replaced?
-Exhaust manifolds

I hope that covers everything I wanted it to. Sorry if that is unnecessarily long. Also, if this needs to go into the Forced Induction thread or somewhere else, I will gladly move it.

Thanks in advance for your advice.

A.R. Shale Targa

iTrader: (2)

Dished pistons are a good way to go since you're freshening the engine any-
ways. Compstar rods are a nice upgrade as well. Your cam choice is decent
although I'd widen the lobe separation to 114-116 range.
Lastly turbos operate on exhaust energy whereby the gasses flow their high-
est velocity when hot and near the engine. Because of this I'm not a fan of
the rear mount stuff although I understand the whole packaging issues.
Try looking at a T4 housing Garrett or Turbonetics where you could package
it underhood in the 66mm to 74mm range with a .96-1.1 range AR and easily
meet your power goals of 500-550 rwhp on low boost and 700ish at 15 lbs.

VincentT

Thanks for the response and thanks for reading all of that. I've done plenty of looking in my engine bay trying to figure out whether or not two turbos would fit in there without doing a lot of cutting and refiguring. In order to front mount with turbos that are of any appreciable size, you have to move a lot of stuff, including losing the A/C. I know that a lot of guys frown upon remote mounts, but with a V, it's also tough to do a traditional mount turbo and keep a stock look. I'm still debating whether or not to put the turbos next to the tranny. That would be a lot of heat on the tranny and floorboard though. Ground clearance also isn't the greatest from what I've seen. I want to do what I can to to liven up the lower end of the RPM range since I plan on doing a remote mount. Hence the twins for quicker spool, smaller LSA, and I'm going to wrap the exhaust pipes and put blankets on the turbos to retain what heat I can.

PS: Thanks for the advice on the turbo sizes.

legen-waitforit-dary

iTrader: (1)

A twin GT28 would have a fairly quick spool. As far as an exhaust system goes you want the least restrictive flow out of it. You may want to get a full custom setup I would recommend a no cat system and the least restrictive mufflers that you can find. The intercooler is big but the more cool air you have in your system the better the performance, plus it will look mean behind that grill. Also like you said wrap everything you can; I understand the money issue but it's like you said you're about to start making money finally so don't take a cheap route that could risk the performance or reliability of your car.

DMM

Go with a 224/224 on 114*...will make tons of turbo HP and will also make lots of NA power while you do the work. You can get them used on the cheap...all you need is the GM LS2 timing chain for $25 and reuse your existing gears with .600" lift valve springs. I would stay stock short block for the time being as turbo's are easier on the internals than any other FI system. Granted, eventually after you work out the bugs go ahead and build with lower CR...but I would not bother with it initially...it's just not worth the expense while experimenting with a new build/design.

I would look into oil-less turbo's also...no scavenge system and spool much quicker. This is what I was attempting before I got my E-Force...the GT-35R compressor map is ideal for twins on a 347. I never had any luck getting info on what was an oil-less equivelant so I gave up and went a route that I knew better.

Good luck!

heavymetals

iTrader: (3)

The only turbo setup that I saw was a ******* joke.

Kept claiming no spool up problems having the turbos in the rear.

IMO, and not to throw cold water on your project, but knowing what I know, I would go big displacement instead.

If you start there, goosing it with FI later is even more fun and a bigger project.

VincentT

Thanks for the advice, everybody. And thanks to whoever moved this thread. I was getting no love where I posted it first.

legen(awesome handle, by the way), I know what you mean about getting the right flow and everything fitting a muffler back there, and a good flowing one at that, is going to be a challenge, but I looked at some novel stuff from Spintech today that may just work. And I totally know what you mean about cheapness. That's what I have all of these mods in mind. I want it to be reliable.

DMM, I still have plenty of cam research to do. I just figured the guys at Comp know what they're talking about when they have a cam just for remote mounts. I think I probably agree with you on an LSA of 14 though. I'm undecided on oil-less though. Pretty expensive stuff. I also like your idea of putting the turbo on before the rotating assembly, I would just limit the amount of boost I run. (I'm afraid I would be too tempted to turn it up though!)

heavymetals, I only plan on taking it to the strip occasionally, so the few tenths of a second of lag that I will lose is acceptable for me. I may go big displacement one day on another vehicle, but that just isn't what I want to do with this one.

Thanks guys.

DMM

With the cam you will never really feel any difference in .003" of lift or 2* difference in LSA as these are nearly within the machining tolerance's. You'll feel a difference in your wallet though.


Ya think?

VincentT

In regards to oil-less turbos, cooling is an issue. I know that some guys on here threw around ideas of self contained oiling systems in rear mounts, and some pulled it off, but what about a self contained water system? I'm imagining a small tank in the spare wheel tub, a small electric water pump, hoses, a heater core, and a small fan hooked to a thermostat. Is something like that feasible? I know it probably wouldn't be if the turbos were near the engine because there would be too much heat for such a setup. But with the rear mounts far from the engine and in an ambient temp environment, would such a thing work? And on that topic, since the turbos are in an ambient temp environment, is cooling even needed?

Dmax/04V

Even with the location of the turbo's you would have some decent heat buildup in the compressed air between the act of compression and the driving force behind the turbine itself.. At the rate the air moves through a system like this it doesn't have time to cool before being consumed.

VincentT

I guess I wasn't clear on it. I'm still going to go with an intercooler for sure for the charge air. I'm going to do quite a few things to keep the charge air cool; turbo blanket, coolant flowing through the center housing, oval charge tubing(greater surface area to volume ratio than circular pipe means better passive cooling on the way to the engine), and an intercooler will do great for cooling the intake temps. I was mainly meaning heat from exhaust gases transferring from the turbine into the center housing. Oil-less turbos have ports for coolant so the bearings and center housing stay cool. They're designed with placement in the engine bay in mind, where temps are high and there is not much airflow. But, in the rear of the car, ambient temps are relatively low and there's plenty of airflow when the car isn't stationary. I'll still go with coolant in some form, I just was curious.

BudRacing

iTrader: (3)

If I were to attempt it, placing them where the stock cats are would be my preference. Sounds like you've done some fair research on the project though and you also sound like an anomaly among BMW crazed med students/MD's who view working on their own car as either beyond their skill level or below their social status. Best of luck!

VincentT

Well thanks. I just can't wait until I can start.

jrane

iTrader: (10)

1. Your rotating assembly is fine
2. The cam I would have a wider LSA 114-116.
3. Dont use a double roller no need C5-R chain is fine
4. Use Arp Head Studs
5. I wouldn't do a rear mount becasue the 3 gto's that I know of that have have done rear mounts have huge problems after 600rwhp. Mount them where the cats would be that would be a better setup.
6. Run your compression around 9.1-9.4
7. Send your tranny to Jason at TDP he's awesome and prices are better than Tick
8. Use a twin disk clutch I have the Ls9 and love it and takes all the abuse I can throw at it.
9. Find a 8.8 out of a cobra and just buy the partial kit Max at Creative Steel
10. Use precision 5858 Turbo's you will plenty happy get them with V-bands
11. For fuel I would use a Surge tank because our fuel tanks are kind of a pain in the *** and not really mod friendly.

Other than that everything looks good to me. Also Since your in San antonio why dont you run E85? You can run more boost make more power and run cooler temps.

itsslow98

iTrader: (18)

As with any build, building from back to front is the way to do it. Start with the rear, fuel system, trans, and then motor. Few things I would suggest, go with a twin disk clutch like MCleod RXT. Don't go with twin rear mounts either if your doing a custom setup stuff them by the transmission or figure a way to get them in the engine bay. For the motor do a stock crank, callies compstar rods, and diamond or wiseco pistons and stick with 9.5:1 compression if your running 93 octane. IF you do E85 I might even look into 10:1 to help spool the turbos. I would sellt he 243s and pick up soem Trick flow or AFR heads because they have a thicker deck more suited for boost.

VincentT

jrane, what sorts of problems have you seen with rear mounts?

I've heard about our fuel tanks. Doesn't sound fun.

And sorry, in St. Louis, not SA.

jrane

iTrader: (10)

My bad for some reason I thought you were in SA.

The problems with rears mount turbos is there good for like 600rwhp then after that you have problems with oiling issues, boost leaks, pressure drops, and just a lot more can go wrong because everything is so far apart basically is the easiest way to explain it. About the only thing rear kits seem to work ok on is Vette's but thats because everything is real close. There are better ways than a rear kit granted it's a cool design and sounds cool, but in my experiences generally stay away from them especially if you want 600whp or more.

The fuel tank isn't that bad and lowering the subframe isn't really very hard at all just takes a little time. Make sure though when you drop your tank you unhook the vent tube to the charcoal canister that's above the diff. If not you will be buying a new gas tank (ask me how I know ) It's hard to see though unless you pull the subframe completly out, so be careful when you go to pull the tank, and the bolts that hold the gas tank straps are ridiculously long.

Also if your goal is 700rwhp out of your car, your 243's are fine just have them freshened up probably will want new exhaust valves, and also do the trunion upgrade to your rockers. After about 680-700rwhp though you will want to port the heads or get a better thicker deck head like AFR, Tricklows, etc. When you start pushing right around the 700rwhp mark on 243's will find out how well your tune is because you can push water, and have other not so good things happen if something isn't right. I've seen 243's and 317's pushed past 1000 rwhp on meth. Just depends on how well your engine is put together, and how good of a tune you have. Your stock crank is good to over 1000 on a turbo setup so on stock displacement/crank you will easly make 700rwhp especially with twin precsion 5858's or 6262's on stock manifolds. If you really want a 383 though then just buy a Eagle Crank, and save your money for other parts. No need for all the expensive Callies rotating assembly or super expensive billet stuff. I don't care what anybody say's (Eagle, callies, and scat) are all made in china, and all quality checked with some final finishing here in the US. Unless you get a "Dragon Slayer", "Lunati", or some Billet crank which are actually made in the USA. You don't need one of those though, it would be complete overkill so Eagle is just fine.

What all your going to need is Motor & Tranny mounts (if you haven't done them yet), LS9 head gaskets, (Cam/pushrods/Springs/Lifters) either get a custom spec'd cam (Pat g, Ed curtis, etc.) or (Speed Inc.'s "TU1 Turbo Cam") it's a good off the shelf cam for your goals, Eagle H-beam rods w/2000 bolt, some "Wiesco" or "Diamond Pistons", C5-R chain or comparable with new timing gears, "ARP" head studs, new oil pump either a Melling "10295" or "10296" (it honestly won't make a difference if you get a high volume pump or not especially if you goal is 700 rwhp). Make sure though you get a new oil pump though! Do not reuse the old oil pump!!!

Also for safe insurance but it's not needed are some ("ARP" mainstuds). They're only an extra $60 by the time you buy the regular main cap bolts, I highly recommend though that you get the ("ARP" mainstuds) though.

Also get a better radiator (Alradco or Ron Davis) the factory raditator sucks especially with the plastic end caps. I had mine crack and break so that's why I now have a ls3 instead of a ls2 long story short.

Your also going to need piping, wastegates, blowoff valve, intercooler, a downpipe, exhaust, oil pump for turbos, along with the oil lines, two turbo's. I think you would really like the precision 5858's journal bearings they would spool quick, and make plenty of power for what you want, best part they're not to expensive.

You also with need a Wideband o2 since your boosted, for your Fuel system 80lb injectors with be fine, your fuel rails though will at the limit along with your fuels line around 700rwhp so you may want to consider a return fuel sytem once hit 650rwhp. Your options are basically to do twin walbro's, have Lonnies do your fuel system, or do a surge tank which will probably be the easiest of the three, and you can keep you stock fuel tank setup pretty much.

A Twin disk clutch you can get a Ls9, McCleod, or any good twin disk clutch (but do not get a single disk if you are wanting to make big power!).

A built Transmission (I would say Jason at Texas Drivetrain Performance) hands down best guy in my opinion, I have yet to see a negative review, and all the tranny's he's done for me have been flawless and taken lots of abuse with no issues. Also if you happen to have anykind of problem whatever it may be, he will get it fixed ASAP! He also has better prices than Tick last time I checked. He may not though answer the phone right away if you call unless he's got another secretary, but leave a message and usually will get back with you by the end of the day. (Turn around is usually about 3-5 days minus shipping time).

Lastly make sure you have a 8.8 or 9in because the factory diffs won't last as I'm sure you know. Your best bet is to just get the partial kit from CS with the upgraded CV's (the factory outter Cv's will break around 550ish) it will be $3100-3200 shipped to your door for the partial kit with upgraded CV's, and you need to source a 8.8 diff. which is usually $300-$1000.

All in all you will spend an easy $12-$14k minimum even if you do most of the work yourself. There is just so much that has to be done to these cars to make them handle lots of power without breaking expecially anything over 600 rwhp. I think though I covered most everything thats gonna need to be done. If you have anymore questions just ask

VincentT

Yeah, I really wish I could go engine bay. Replacing the cats is an option, but I want to "keep" the cats for inspection purposes. Plus, the ground clearance is an issue for turbos by the tranny that I haven't figured out yet. I'm pretty dead-set on going rear mount to start. But, now that you've said this, I will probably pay much more attention to detail with it. If it goes wrong, I give you permission to rub it in.

Good to know about the oil pump. Hadn't thought about that yet. Does your oil pump advice still apply if I go oil-less? I'm assuming it does.

That's also great to hear about the crank. One less thing to replace. I plan on not going past 700rwhp, so my heads should work. Assuming the blanket 15-20% loss from rear to wheel, that's well over 800 flywheel. That works great for me. I also plan on ARPing everything.

Sounds like Jason at TDP will be getting a call from me.

Excellent advice all around, good sir.

jrane

iTrader: (10)

You can mount the turbo's where the cats are, and put some bullet style style cats behind them. It's been done before with great success. In cadillac forums under "My twin turbo 408 is almost done" thread.

You will still need a new oil pump regardless if you go oil or oil -less turbos. If you don't use oil-less turbos you will need a auxiliary oil pump to feed and the oil to the turbo's because you won't be able to gravity feed the turbo's

VincentT

That's a good idea and very similar to the other builds like that I've seen, and I certainly see the merit of having such a setup. If I was just going to cruise this car and take it to the strip every once in a while, I would do that. I just think the rear mount fits my plans better because I don't trust the ground clearance and heat of those other setups. I want to be able to drive the car to work any given day, even though it won't be my daily driver, and calling the roads around St. Louis "challenging" is a generous assessment.

Thanks. Yeah, I've read up plenty on the scavenge pumps and everything. As such, I'm thinking that oil-less turbos, while more expensive, will be cheaper for me in the long run. But new oil pump it is.