turbo 4.0 questions - Page 2

GIJohnnyB · 07-15-2010, 05:47 PM

My old ride.

1992 Toyota MR2 Turbo

Fully built motor, JE Pistons, HKS Metal headgasket, Custom tubular exhaust manifold, Turbonetics external wastegate, Garrett T4 turbo, and on, and on.

Best 1/4 mile = 13.12 @ 107MPH

flatlander757 · 07-15-2010, 05:47 PM

I'll also add that Unlimited04 is right... a correctly sized turbo will work much better and work and spool quickly and very likely outperform a supercharger.

For a VERY good build up and info on turbocharging... look here:

400HP pump gas friendly 4.5L stroker - Pirate4x4.Com Bulletin Board

But keep in mind you can dump all the time and money you want but if you don't regear it will still be a big slow POS and you'll look like an idiot going "PSSSH" in a Jeep that can't crawl a moderately sized rock without either killing your clutch or cooking your auto trans fluid.

LKrux · 07-15-2010, 05:47 PM

Quote:

Originally Posted by freeskier93

Good luck finding a turbo that will spool up fast enough to be of any use while crawling at 1-2 mph. Supercharger might be of more use.

But if you're going for Mall Crawler status by all means put in a turbo. If you want to beat the ricer honda civics then buy a prius.

Edit: OK, maybe mall crawler is a little harsh because who doesn't want a turbo in any car?

a turbo can spool up fast enough to be usefull offroad. it depends on your rpms and the size of the turbo....

in 4lo your rpms get pretty high sooo im sure a turbo would kick in fine. It also depends on the size of the turbo.a smaller one would probably work awesomely.

this has been done, but i think its too much work for minimal gains. sure its badass and id love to have a turbo jeep but im not sure how long the stock internals would last due to that extra pressure.

id rather re-gear and get a nice exhaust

and if your feeling froggy, swap in a v8

**freeskier93** · 07-15-2010, 05:50 PM

I stand corrected.

**Unlimited04** · 07-15-2010, 05:53 PM

Quote:

Originally Posted by freeskier93

What kind of torque are you getting between idle to 1500?

it aint mine...ask scrapinrocks'. i know lots of turbo builds are on Pirate4x4, and if done properly, a 4.0L turbo will run like a scalded dog.

never monday · 07-15-2010, 05:55 PM

Quote:

Originally Posted by freeskier93

OK, maybe mall crawler is a little harsh because who doesn't want a turbo in any car?

me

GIJohnnyB · 07-15-2010, 05:57 PM

There are plenty of turbo's that will spool at low RPM. But then what? You'll have boost as soon as you hit the pedal and nothing up top...it wouldn't be much of a daily driver at that point. Turbo's are meant for RAW power as where a supercharger is belt driven and can be more controlled by throttle and gives a nice addition to your torque all the way through the RPM range.

LKrux · 07-15-2010, 06:03 PM

Quote:

Originally Posted by GIJohnnyB

There are plenty of turbo's that will spool at low RPM. But then what? You'll have boost as soon as you hit the pedal and nothing up top...it wouldn't be much of a daily driver at that point. Turbo's are meant for RAW power as where a supercharger is belt driven and can be more controlled by throttle and gives a nice addition to your torque all the way through the RPM range.

this is just speculation.
i agree a supercharger is more "even" in delivering power.
and once the turbo spools, it keeps spooling. the more you give it gas the faster the engine shoots out exhaust, which turns the turbo.
so the more you use the skinny peddle the faster the turbo spools as the rpms rise..

but it all varies in different setups. depending on the size of turbo used and what not

**freeskier93** · 07-15-2010, 06:08 PM

Quote:

Originally Posted by Unlimited04

it aint mine...ask scrapinrocks'. i know lots of turbo builds are on Pirate4x4, and if done properly, a 4.0L turbo will run like a scalded dog.

Oh, okay.

flatlander757 · 07-15-2010, 06:14 PM

Quote:

Originally Posted by LKrux

this is just speculation.
i agree a supercharger is more "even" in delivering power.
and once the turbo spools, it keeps spooling. the more you give it gas the faster the engine shoots out exhaust, which turns the turbo.
so the more you use the skinny peddle the faster the turbo spools as the rpms rise..

but it all varies in different setups. depending on the size of turbo used and what not

And that is why you need a correctly sized turbo.

At some point the exhaust side of the turbo will get "backed up" and power stop building as rapidly with RPM because the exhaust gases can't escape through the hot side of the turbo quickly enough.

Also people think "OMG 20psi awesomezors!!" and they're idiots.

PSI = a measurement of restriction.

If you bolt on a decent turbo and build say 8psi at 3000rpms(for examples sake)... then you port the heads and/or install a larger A/R exhaust housing on the turbo(A/R = cross sectional area ratio) you may be building 6psi at 3000rpms now... but you'll be making more power.

Why?

8psi may be 100CFM going through a 0.48" A/R housing

6psi could be 130CFM going through a 0.60" A/R housing.

Since the housing is larger... more air can pass through at a given time at the same or lower pressure.

It's not boost that makes power... it's AIRFLOW!

And that misconception is why everyone is generally retarded when they talk about turbos

edit:

Also, you need to look at turbos and their compressor "maps" and know how to read them so you can stay in the range where they are efficient. At some point in all turbos they will become "efficient" as they get enough exhaust flow for a given engine size and exhaust housing. Also at a later point they will start building heat and become inefficient because they start building more and more pressure(which adds exhaust backpressure = strain) and all it will do is become stupidly H-O-T air. They get to a point where the intake air isn't supplying enough CFM to adequately get through the motor fast enough to pump on the exhaust side of the turbine to make more power.

My $0.02.

jwcardy · 07-15-2010, 06:23 PM

Quote:

Originally Posted by flatlander757

It's not boost that makes power... it's AIRFLOW!

And that misconception is why everyone is generally retarded when they talk about turbos

I have been trying to preach that for years...
-wes

**chmo** · 07-15-2010, 07:07 PM

is the RIPPMOD ripp SC for the TJ finally available ?
additional 100hp on the rear wheel ... continuous torque and HP build up ... washer methanol water intercooler

search for RIPP SC

GIJohnnyB · 07-15-2010, 07:35 PM

Quote:

Originally Posted by LKrux

this is just speculation.
i agree a supercharger is more "even" in delivering power.
and once the turbo spools, it keeps spooling. the more you give it gas the faster the engine shoots out exhaust, which turns the turbo.
so the more you use the skinny peddle the faster the turbo spools as the rpms rise..

but it all varies in different setups. depending on the size of turbo used and what not

It isn't speculation, its fact. Yes the turbo will still be spooling but it can only spool so much and depending on the size it will only push out so much PSI. With a smaller turbo, that will spool at a lower RPM, once you get to the higher range of RPM it isn't going to provide much power, the turbo just isn't able to provide the airflow.

**Sundowner** · 07-15-2010, 08:28 PM

I'm surprised there hasn't been more discussion on how a 4.7 stroker might work...

With that said, I used to be of the opinion that a turbo was a very, very bad idea in a Jeep. However, I have to admit: it can work, and quite well at that. As has been said, it all has to do with airflow and proper sizing. Turbos can make some serious power...however, there's just one more small fact that the OP needs to consider: THE REST OF THE DRIVE TRAIN.

If you're going to put 250+ to the rear wheels, then you're going to have - in my opinion - to do some serious beefing up, or parts will start failing...especially if you're driving it hard on the street.

rubidriver · 07-15-2010, 08:58 PM

Quote:

Originally Posted by GIJohnnyB

It isn't speculation, its fact. Yes the turbo will still be spooling but it can only spool so much and depending on the size it will only push out so much PSI. With a smaller turbo, that will spool at a lower RPM, once you get to the higher range of RPM it isn't going to provide much power, the turbo just isn't able to provide the airflow.

Na man its speculation.

First, yes the turbo can only spool so much.. what is your alternative? A supercharger? Ok, lets stick a small pulley on the SC to make tons of boost and blow it up before it gets out of the shop.

Second, your acting like there are just big and just small turbos out there. If sized right you can find your medium and it will make more than enough power.

Third, if your not happy with my "second" then you need go ahead and get together with the guys from Porsche and get you a variable speed turbo, so you can have the best of both worlds and be happy. Just a little warning tho, you arent going to come back bragging how cheap it was to us later with this choice.