Terbamercherger qwerschunz.

So if a particular individual were to have invested nearly no money into a project that was ripe for adding boost to and that particular individual really wanted the vehicle to go from "Torquey and fast" to "Holy shipsticks will it ever stop?!?!?!?" using boost AND the addition of said boost should be unique in its presentation but absolutely must be OE reliable in its delivery and cheap to nearly free in cost: WWGRMD?

The vehicle in question may or may not have the following specifications:

Weight: @ 2720lbs wet w/o driver Cylinders: 8 totaling roughly 4800cc Gears: 4 forward with 3.42:1 final drives 100" wheel base, fixed roof, two doors, no issues with grip as tires ranging from 205/55r16 to 275/40r17 can be used on all four wheel positions and up to 335/35r17 will technically fit out back if that particular individual, mentioned before, could afford the wheels.

No other answers regarding the vehicle will be provided.

Initial though was a turbocharger properly sized for each set of four cylinders focusing on maximum HP giving up a small amount of torque.

Secondary thought was a turbocharger slightly undersized for each set of four cylinders with a third large unit scavenging the combined exhausts for higher RPM use, in effect creating more power in the middle and higher RPM, without all the pesky lag.

Is the second theory sound? I know twin charging works, but this would be done on very constrained budget... think two Passat/Audi KKK03/04 turbochargers and a bigger Dodge Holset all feeding into a single charge cooler with simple boost control devices.

What would YOU do with, say, an extra $900.00 or so in your budget for this type of modification?

another certain individual will be eagerly awaiting answers to the aforementioned individuals query

"Holy shipsticks will it ever stop?!?!?!?" using boost AND the addition of said boost should be unique in its presentation but absolutely must be OE reliable in its delivery and cheap to nearly free in cost: WWGRMD?

Tell you that "if you have to ask, you cant do it".. at least not for free AND with OEM reliability.

Now if you merely want an attainable result i would say your first decision is between new Ebay turbo and used OEM turbo from a big truck. I would definitely use a single turbo setup for simplicity and cost efficiency. If you really want it to be fast i'd err on the large side as well. A larger turbo is going to be more complimentary to your powerband by spooling later and be more efficient both in higher adiabatic efficiency and lower pumping losses. Remember, a 2700lb car with a 4.8 doesnt need any help down low. You want a setup that will extend your powerband and only give you as much power as you can use at a given rpm. If you try to build the fastest spooling setup possible you will have a crappy powerband and unmanageable wheelspin.

So for a 4.8 you want to be looking at some fairly big turbines. If people are using a turbo on a 4 cyl that spins to less than 9000 rpm, it's guaranteed to be too small for you. Unfortunately retail sellers like to characterize their turbos in HP limits which usually represent the compressor side more than the turbine side. You want what most people would consider a pretty big turbine section. Like a Q-trim T4 turbine wheel in a ~1.00 a/r housing, maybe bigger.

That all depends on what you want. A single turbo will be slightly laggier simply due to time it takes for it to spool. You'll also be running a comparitively larger turbo that say, a twin setup, or a sequential. For the sake of argument, i'm going to go ahead and throw sequential out the door, because that's kind of a pain in the ass to deal with. If you want to spool a big turbo quickly- spray it.

In THEORY- your second idea could work. The piping would be a frickin nightmare, and I don't even want to think about oil delivery. That just sounds like a mess waiting to happen, to me. You're also looking at compounding (see what I did there) WG issues, BPV issues, fuel delivery, and so on. In practice...... yeah. I guess it depends on exactly what this hypothetical vehicle is being designed for. My inkling tells me this is either an SBC OR- a german v8 of some oddball fashion. I couldn't give a more educated answer without knowing more details, but from what i'm reading, your theory is sound.

4.8 has 280 ftlbs torque by the time the torque converter quits helping. One oversized turbo gets my vote.

Best bang for the buck i have done was hands down a single holset on a 302. It had twin td04s at first, but for simplicity and packaging I went with a front mount single. I didn't find a real performance benefit to the twin turbo setup, but that was probably at least partly due to the crazy plumbing.

I've never done it, but I've heard that junkyard mitsubishi eclipse turbos give a good bang for the buck

Most Holsets from 3/4-1ton pickups are going to be too small for a 4.8L gas v8 unless you get one of the early cummins 5.9 ones with the massive a/r turbine housing. They will all flow 5-600hp (the ones that came on 5.9 cummins, i mean), but most of them the turbine housing is way too small for what you want.

Keep this in mind about turbos off of diesels: Diesel motors generally flow like TOTAL dog sh1t. So even thought you might think a turbo on a ~6.0L diesel is big, the turbine is really only appropriate for a high performance gas motor of maybe half the size. If you put one on a gas motor of the same displacement it will spool way too early and peak too early and probably need wastegate mods to avoid boost creep.

So if you're looking for big used turbos off diesels, you're going to have to go bigger than a 1ton pickup in your search for donors. My .02

Well, I have a brand new Garrett turbo from a Caterpillar Marine engine, if you need something more along the lines of "will it ever spool...HOLY F***"

Comes off of a bank of cylinders totalling 16L, so take what you may from this.

sobe_death wrote: Well, I have a brand new Garrett turbo from a Caterpillar Marine engine, if you need something more along the lines of "will it ever spool...HOLY F***" Comes off of a bank of cylinders totalling 16L, so take what you may from this.

I suddenly feel insignificant. Mines from a puny 12L. :(

On the other hand.........I do have two of them.

With a five-liter engine, there is no such thing as turbo lag if the turbocharger is in the engine bay.

An ordinary 305 gave unnoticeable lag above 1500 RPM with a Garrett T6 truck turbo. That was the stall speed of the torque converter, so I couldn't tell what it did below there. Caleb got 300 horsepower at 3600 RPM, and above that the wheels spun on the dynamometer.

You'll want one appropriately-sized turbocharger, placed for convenient plumbing, and the largest intercooler you can feed. You'll also want to duct all of that air out the top side of the car.

Is this for daily driving, autocross, drag racing, or track day?

What did spell check say to that thread title?

A Chevy LS292 with a turbocharger might be an "all-purpose" engine. You could be looking at 550 lbs*ft from 1500 to 6500 RPM. It would be good at daily driving provided proper fuel/spark maps, good at autocross provided you could get traction anywhere, good at drag racing provided you didn't hit the rev limiter in 4th by the end of the quarter, and good at track days provided you could keep it cool.

Garrett TO4B from an International dump truck. It's been done before!

Gearheadotaku wrote: What did spell check say to that thread title?

Just about what you did when you wrote it... "John has been hitting a little of the nitromethane again!"

The plumbing issue and boost reversion have been addressed and are able to be resolved in budget, wether it be one two or three turbochargers there will be room for them and the plumbing. The vehicle may not even need boost after the engine is actually set and running.

Traction is mostly a non issue, but steering it under throttle may be a problem.

Some people will probably think that's a joke based on that little 900-1400hp graph but i think that's appropriately sized for a 4.8L even if you only plan to make 600hp.

Vigo wrote: Some people will probably think that's a joke based on that little 900-1400hp graph but i think that's appropriately sized for a 4.8L even if you only plan to make 600hp.

600 hp is only about 60 lb/min airflow, barely past the surge line for that 5518. Not an ideal choice.

turbobygarrett.com has a "boost advisor". For that application, they suggest just about any 4xxx series turbo.

I'd run a pair of td0413t s from xc70 volvos. Junk yard cheap and headroom for 500hp, small enough to be responsive.

600 hp is only about 60 lb/min airflow, barely past the surge line for that 5518. Not an ideal choice.

That's the problem with buying turbos over the counter. They match turbines and compressors based on very general rules of thumb. If OP wanted to pick a turbo that spools the way i recommended but was also in the compressors efficiency island at the relatively low hp level he's probably seeking, he'd be hard pressed to find an over-the-counter turbo with a turbine-compressor matchup that would do it. If you really want to get something ideal you're better off rolling your own but thats probably out of the budget in this case.

But, to be clear, 60 lb/min is not at the surge line on that turbo until you get up to ~2.7PR. It's not going to take anywhere near that to make 600hp on a 4.8. At 60lb/min and lower PR it's at a perfectly respectable efficiency.

(I think he just spoke Canadian ;) )

I haven't seen it mentioned yet but can the existing injectors keep up? Can the stock computer handle boost?