i have been doing extensive research and asking a lot of questions about going turbo in my vet. i havve finally decided to go rear turbo with my vet and have been in contact with sts turbo systems. going back and forth with them, the kit they have for 3500 includes a garret turbo, electric oil pump system, air cleaner and oil pipe lines and turbo flanges and a waste gate. after discussing this with some forum members, all of you came to the same conclusion. 3500 hundred for a turbo and an oil pump. this does not seem right. the turbo isn't even a ball bearing design. and it doesnt come with piping going to and from the turbo. as of right now, they do not have a specific turbo kit for c4's.
after i concluded that this was way too much for the kit, i asked them if they would just sell me the electric oil pump system, and the flat out refused. they said that the system only comes with the turbo kit.
for 3500 i can get a dual ball bearing turbo ($2000), and fab up my own oil pump kit, and still have 1500 left over for everything else. right about now the c4 turbo kit from hpturbocharged power sounds real good to me. only draw back to that system is what? what do you guys think?
The only picture I ever saw of a HP system had the turbo sitting right where the battery and crossbrace that goes over it are. Right next to the brake and clutch cylinders and where the tires would throw water if you went through a big enough puddle, no matter how well sealed. It just seemed like a really bad spot to put it. But I hear it works well so I guess that is the final thing. Although the 2 month lead time would scare me a bit. I hear they work well though so again. Not sure.
That is what i was wondering, would that air filter get dirty much faster, or wet? I guess it only matters if you are going to only race it. What is the benefit of having the turbo rear mounted? Just space?
That is what i was wondering, would that air filter get dirty much faster, or wet? I guess it only matters if you are going to only race it. What is the benefit of having the turbo rear mounted? Just space?
Two benefits: Space and heat
There isn't much room in the engine bays of the C4's to begin with, and those turbo's are HUGE heat sinks you need to deal with.
Having a turbo sitting by my brake booster, no matter how much shielding, would scare the crap outta me. Just my 2 cents, but that is where I plan on putting my scavange tank for the dry-sump system.
The other thing a rear-mount will do is make it MUCH easier to change plugs. The gyrations needed to plumb a turbo under the hood, and to work on it afterwards, make me look at a rear-mounted turbo more and more.
I can agree, the easiest way to turbo a C4 would be a rear mount.. that being said.. a front mount setup is only cumbersum to work with or around if the design is poor. for example I can have mny turbo and entire exhaust system off my car faster then a regular set of headers and exhaust from a stripped down 96 with long tubes. and if your talking about cast manifolds.. I would change plugs in my turbo car any day of the week and twice on tuesday before wanting to tackle a stock manifolded cars plugs. then again, i took my time and made sure all my connection joints were very easy to get too, the V-band connections are a no hassle one nut removal, plug access was important for frequent plug changes for higher boost needing much colder plugs and then swapping back to everyday heat range that won't foul out. so yes the conventional turbo location in my opinion is still a better choice provided your willing to do the work and plan out what your doing carefully!
Another issue for those with smog tests, is that a rear mount would be considered a CAT back mod, and thus exempt as long as it wasn't hooked up etc, which means that all you'd have to do is disconnect the Turbo's output pipe and reconnect the stock air bridge to pass the visual (along with swapping out a EPROM and possibly swapping Injectors etc), which is simple enough to do every couple of years.
I'm not entirely sure about this but it makes sense (out of sight , out of mind)...
Doug
Quote:
Originally Posted by Joe90
Two benefits: Space and heat
There isn't much room in the engine bays of the C4's to begin with, and those turbo's are HUGE heat sinks you need to deal with.
Having a turbo sitting by my brake booster, no matter how much shielding, would scare the crap outta me. Just my 2 cents, but that is where I plan on putting my scavange tank for the dry-sump system.
The other thing a rear-mount will do is make it MUCH easier to change plugs. The gyrations needed to plumb a turbo under the hood, and to work on it afterwards, make me look at a rear-mounted turbo more and more.
It's really not that hard.
1)you have to build your own crossover to move the exhaust to the drivers side only (in front of the pan).
2)Run single 2.5 (for t4) or 3"(for t6) back to the spare tire area.
3)build a hanger mount from the frame over the rearend with a threaded stud hanging down on either side to attach the turbo cartrige to (if your using the"TV" series garrents) or aother form of bracket to suit your turbo.
4) For street Id use a GT4202R with a 1.01 housing
run single 3" for cold side back up to the engine compartment (using the other side of the exhaust tunnel)
5) cut the a/c box corner and re fiberglass the piece in backwards to make room for the compressor piping (often you'll need a shorty or custom header to make room, but It looks like a roadmaster log would help fix that.
6) the compressor pipe will need to be made oval where it passes by the header-a/c box. Use a 2x4 cut into a triangle at the end and hammer the pipe while working the "tiangle end" in until you have your oval pipe
7) If your car is MAF the BOV must be attached prior to the sensor or she'll stall when you shift/come to a stop
8) tap into the oil pressure at the oil filter pad
9) Shurflo 3 diaphragm 3.4gpm chemical pump. I have tried darn near all pumps availible and this is the only one that lasts. It will handle your return needs, and since it's a positive displacemnet pump it self primes. Use a relay and wire the trigger in with your fuel pump relay. that way if there has been any backup in the line while it was shutoff, the quick prime it gets when you turn on the key will take care of it.
Mount it in the back someplace and return into the oilpan, above the oil line.
10) Unless your an electronics/programming guru Just save yourself the hassel and go aftermarket with your engine management.
11) Have fun!
a few questions, is what are the advatages/limitation of running 2.5 inch piping down to the turbo??? are they much gains in running 3inch??
also how would the GT42 you said compare to the turbonetic T76 (i think) like what the single STS guys are running one the F bodies? and what power could you get out of a GT42 on say a 350?
Not a pain at all!
The Gt4202 (which is the higher flow compressor as opposed to the GT4294) can support well over 1000 hp. That being said they are just as happy at 500 hp.
The Gt4202 has a 74mm inlet,102mm OD compressor. The T-76 has a 76mm inlet and also a 102mm od if IM not mistaken.
I having tried them on a couple different cars and tractors, Id say the "new" Gt series are in everyway superior. You can't believe how fast the BB ones spool.
Check them out at www.turbobygarrett.com. It's the largest BB turbo garrett makes.
The 2.5" might keep exhaust velocity a little higher and make it even easier to package. Not sure when It would become a real restriction.
i spent a lot of time looking in to Evos and know from others results jsut how effective the GT seriers of BB turbos can be! just strange that more people dont use them, but then i guess its less of a probelm!
Have seen an Evo making 988bhp ant the ($ lol) wheels usingone of thoes beats!
BTF, sorry to keep questioning you vast knowlage, but i have been looking and wondering about the GT42 you recomended. i know alot of the F Body guys are running the T76's (similar size to the GT42 right) on their STS setups. the thing is they are running small A/R's. like .64 (i think)! and when they move upto larger A/Rs they are making less bost because the turbos are flowing TOO well.
do you still think the GT42 with the large 1.01 A/R would work????
sorry to question you as i dont know a lot about this, but thats why im asking!
I know that the A/R is not a constant number between turbos meaning the Aspect Ratio for the turbine scroll will have different effects with different turbine wheels. to compare them you would need to be comparing the same turbine wheels for spool characteristics. so for example, I run a .96 A/R on a GTS turbine wheel and spool is moderately laggy compared to the same turbo with a .82 A/R. but it has a higher choke point.
on the GT42's the wheels are quite efficient and will not require such a small A/R to achieve spool.. the benefits to this is a much higher choke point for more power higher in the rev range with comparable spool characteristics of a less efficient wheel and a smaller A/R. also the bigger the turbine wheel the greater the rotating mass is which will contribute to more energy required to get it moving.. but it will allow for greater torque coefficient to be introduced across the longer blades making it easier to turn a larger compressor wheel thus achieving a greater mass flow of air on the inlet side for charging the engine.
so yes, in my opinion even though that is a very efficient wheel, the pumping losses from heat being absorbed and dissipated pre turbo on a rear mount will still be happier with a smaller A/R. I believe on Bruce's setup they actually had to cap one of the turbine inlets to get spool sooner. this effectively made the turbine less efficient running off only one half of the scroll and exerting energy on less area of the turbine blades. but increased spool by increasing velocity of the exhaust energy. a smaller A/R here I believe would have made better use of the turbine side of the Turbo and still not been near the choke point since the air flow had already "shrunk" due to loss of heat. the volume has decreased with temperature drop and even though it is the same amount persay of air, its compressed volume decreased by becoming denser and more compact requiring less of an cross sectional area to allow the same flow. I believe they were having trouble finding a smaller turbine housing for the model they were using, they may jump in to verify that but you have more options with the Garret units then the TV series they were using.. but you will ultimately have a higher initial cost layout for the Garret turbo.
BTF.. feel free to hop in, alot of the info from Bruces car was only from posts made while working kinks out, and its been a while since I read them so my info may be off.. let me know!
Location: Boston, Dallas, Detroit, SoCal, back to Boston MA
If all you need is a scavange pump, if you plug into the engines pressure system. One's available. It's used on LSX drysump systems who's pressure pump is not in the pan.
The detroit diesel series 60 uses a high pressure ratio (BILLET TITAINUM WHEEL!) version of the GT42. If I remember corretly it can make like 5.5 bar absolute.
It has a pnuematic actuator that is augmented by a vacuum pump for vane control, along with a shaft speed sensor. They are T6 flange and have an A/R of 1.72. In my experiance with the WRX VNT, the vnt can simulate a reduced A/R that's roughly 40% the size of the parent A/R. But thats a slighly different design so it might be apples to oranges. We would need to get our hands on a turbine map for it to be sure. It might be large enough that a wastegate would be unnessicary, yet be able to provide an adequate boost threshold.
They go through on ebay every now and again, I have taken the part number to my garret dealer and doesnt come up. Basically I need the Detroit diesel part number to find out what they cost. From what Ive seen on it's smaller GT37 variant it's similar to BB prices.
From your last post on the GT42R, After seeing 2.0L spool them up by 4K or less on the 1.01 housing I think your v-8 would do just fine. As an option, it could be custom machined for a flap on one side of the split tangential. Call it a poor man's VNT.
Chris- I couldnt agree more on wheel efficiencies. By permanantly blocking off one side, It did feel somewhat "corked" right after the onset of boost The housing should be modified for the actualtor and flap that he already bought. Or we can take the whole turbo, replace the hot side backplate, turbine wheel/shaft/bearing, and turbine housing for one that came out of a TV71 or TV66. It has a 35% smaller turbine wheel and the parts should slide right into the center housing. The only custom part might be a ground sleeve to make up the quill Dia difference on the compressor wheel.
Last edited by Baldturbofreak; 06-24-2006 at 09:44 AM.
would be nice to see a 92-96lt1-lt4 kit produced. People seem to forget about the L98's and LT1's and are swamped by all these LS1 guys/gals. No disrespect to the LS1 owners but no everyone wants to buy one and definately don't want to spend the money for the parts for one.
Corvette Store
a different spin on the rear turbo
