4doortypels

iTrader: (39)

originally i was thinking about doing a 370 rear mount turbo set up on an 07 ctsv. i ended up getting an awesome deal on a fully forged stroker set up. so i had originally planned on the motor be smaller cubes, but ended up with 408.

its an iron block, eagle forged crank, wiseco -28cc dished pistons, callies connecting rods with arp 2000 rod bolts. Fully CNCed LS3 heads (intake, exhaust ports, bowls, and combustion chambers as well) arp head stud kit, DM performance main girdle with arp studs, tons of other goodies...

Thunder racing camshaft 215/230 .609 .607 117 lsa

already have a ported oil pump ported ls3 intake, ported ls2 throttle body, aeromotive fpr, aftermarket rails resized ls3 83lb injectors...

anyways, i picked up a TC78 with an upgraded f1 billet wheel (new in the box) with .96 a/r. im shooting to make 700 to 750rwhp on a V. its going to be a rear mount set up as you all know front mount is mission impossible 5 (so crazy it skips MI4) im more than sure i will need a larger housing on it... im readin up on 1.15 no split housing, and i thought i saw one with a 1.32 a/r housing. im thinking the TC78 should sufice with a larger housing being a rear mount set up. compression i calculated close to an 8.4 :1

its going to be a street set up, with the occasional track visit just for fun. any opinions on the turbo size for a daily 408 rear mount turbo set up. i want quick spool, but the extra 38 cubes should be nice to have. again this was going to be a stealthy cam with a 370, but the 408 will sound stock more than likely lol...

the cam shouldnt bleed boost, so the turbo should be quick, and a larger frame turbo would probably hang and hit every speed bump.

any thoughts on the rear mount 78 ???

killernoodle

Should be perfect for rear mount with that motor combo.

chris@hps

Alot of rearmount threads lately. We just finished up a custom rearmount on a TA with a forged 346 ,and a 76mm turbo. Made 665rwhp. Your goals are very obtainable, We are pretty close to you as well in powder springs,GA. We have another custom rearmount turbo kit we are doing now as well with a 94mm turbo. You can call me and we can help you with the setup.

Chris

Sarg

iTrader: (6)

Seems like that would add a ton of unnecessary piping and complication to just about any build. You should be able to find room in just about any car to mount it up front and keep the heat closer to the turbo.

4doortypels

iTrader: (39)

ill have to swing up there sometime and talk about it... id love an under the hood set up but the room in the V makes it impossible, ive seen one online, and he ended up switching to rear mount. what size a/r housing was on that 76mm? i think with more cubes id like a little more top end, since the extra 38 cubes over the original 370 will supply the extra low end torque... with the extra torque, the lag should be less apparent. i know turbos like the shorter stroke, but a 408 is a very proven set up as well

Sarg

iTrader: (6)

You would be amazed where you can find room. That is a LOT of heat energy lost going that route.

4doortypels

iTrader: (39)

if you feel like cutting out and welding supports for your frame you can... for a daily set up, it seems rear mount on a ctsv makes the most since... i would love that baby 78mm thrown in behind the headlight for everyone to see... i have seen one under the hood, it looked like a 60-1 where the battery was, and the guy who did it ended up switching it to rear mount due to tunning, under the hood temps, fumes coming through the vents... but as far as building a custom under the hood turbo set up, i have had 6 shops turn the idea down... its not like a GTO or F body set up... it doesnt have the space in front of the motor behind the radiator and all that... if i could do the traditional set up, i would... all i need is piping wastegate and bov. so a rear mount can be had for 1/3 of the price with all i have left i can get a g force 9inch IRS rear end... rear mounts may be down slightly, but they do offer some benifits as well, less **** under the hood during maintenance, lower IATs, own oil supply not shared by contaminated oil from the motor... any turbo system is a system... you are suppose to match parts... just like you would an NA car... my set up is all basically limited to 1100 hp... thats where my turbo is rated to run out, where people start having issues with lifting 4bolt heads, its where my 83lb injectors are high on duty cycle etc... i think my 700-800 rwhp is reasonable, but my biggest restriction i think will be the tiny A/R housing. a lot of guys look at peak to peak numbers, one cam may pick up 10 more hp, but drop 22 tq down low, may not be a big deal if you are running high rpms most of the time, but in a daily, its nice to pick up 20 tq under 3000 rpm and carry across the rev and be down 10 hp peak to peak... that extra 10 hp you pick up at 6500 to 6700 to me isnt work the extra 20 tq that carries from 3000-6500 damn i got way off subject

Sarg

iTrader: (6)

A lot of guys talk about the whole under hood temp thing....yes could could see an increase of maybe 5-10 degrees But provided you have wrap and ceramic coatings, it is minimal. Just remember, your exhaust is still under there...turbo or not!

As for the oil thing and having a stand alone oiling system....that also seems like a lot of extra weight and complication (not to mention more parts to fail) that is not really needed. The effects of a modern ball bearing turbo on the oiling system are minimal. Take for instance the Garret GT ball bearing turbos or the new Borg Warner EFR dual ceramic ball bearing turbos. Their oil use is absolutely minimal compared to the old technology of previous turbos.

Fumes from the vent seems odd to me as well. The only thing I could think of is that they left the PCV system open to atmosphere on a breather system. I really fail to see how adding a turbo could cause "fumes" in one location and not the other. I mean it is not as though a turbo sits there just throwing off fumes by its mere presence, lol. I guess they could have been dumping the wastegate or BOV to atmosphere as well. But there are solutions to that as well.

The packaging of the EFR series also is pretty cool as the BOV and wastegate are all integrated into the turbo itself. While this adds a bit to the length, it saves a ton of space in the long run and no "fumes" under the hood as the BOV vents back into the turbo as well as the wastegate dumping back into the downpipe. My partner is working on putting two of the 1000 hp variety EFR 9180's under the hood of a 2011 Z06 that everyone said would have to be rear mounted

I just feel that the added complication and wasted energy of a rear mount is not worth it. Much slower spool and loss of energy are not benefits to me. But it does cost time and energy to make something custom. It is a shame there is not more out there for the CTSV. That is one of the cooler cars around in my opinion! Seems like someone should make a good front mount kit for it!

Monza355

iTrader: (3)

Lets here more about the rear mount CTS-V. It's like my Olds with very little room up front, yes it has been done but the rear mountis a packaging solution.

4doortypels

iTrader: (39)

i agree... i think he removed the cover in the engine bay for clearance... ii would love to do an under the hood set up... under the hood would be sick and very nice to show off... but my pockets are limited... would have to get a gforce 9in irs set up too lol hopefully this rear mount thing works out unless someone wants to use my car as a test car... but no intrest from any shops lol

Sarg

iTrader: (6)

My guess is that if the rear end needs upgrading, it will need to be upgraded regardless of front mount or rear mount Oh and honestly, no matter what the power goals, that turbo is pretty TINY for your motor...unless you plan on using two of them!

chris@hps

Rear mounts are not all bad if done correctly. I had a front mount setup as well with the headers and wrapped. Still alot of heat under the hood.Also laggy without a t-brake/ 2 step. Also, with the headers and being wrapped under the hood, have your customer change out the spark plugs one time and he will be cursing the car the whole time doing it. . With the rear mount, no heat under the hood, spark plug change is normal, everything under the hood remains the same except for a charge pipe to the TB. I would sacrifice a little lag for the ease in maintance when its time on the engine especially for the person who likes to change there plugs and oil at home.. Rear mounts do make good power and usable power as well when done properly. The oiling for rearmounts, definatly a dedicated tank and its own oil pump in the rear. Some of the fastest mile cars are rear mounted, as is some of the fastest 1/4 and 8th mile cars run rear mounts. They do work, when done properly.

Chris

Sarg

iTrader: (6)

Or ceramic coat and there are no spark plug worries

chris@hps

Just changing the plugs with a set of up and forward facing headers even ceramic coated is a pain in the butt. Especially on a vette. My T/A I had to change all but 3 plugs from the bottom. Ceramic coating is also not enough to keep under hood temps in check ,especially on a streetcar. Ceramic coating plus heat wrap is the best to use to keep under hood temps in check.

Chris

Sarg

iTrader: (6)

Funny I have never had an issue. But then I have access to a guy with all the cool tools As for the underhood heat from the headers, you will have to do something about that (be it wrap, ceramic or both) no matter if it is front or rear. The headers don't go away because you go rear mount, nor does the heat they produce!

Don't get me wrong, rear mount has its place...we are building a rear mount twin turbo car as we speak, but that was only due to customer's preference.