Turbocharging a 4.6 V8
#22
07-16-2015, 07:44 PM
So, I've been chewing on this idea for quite some time. I've done about all the research I can on my own and now I'm looking for some actual help.
I want to turbo my 4.6. Right now it has a Kent H180 cam, Rhoads lifters, Port and polish, intake, and exhaust. It runs like a top and I love driving it. Until I have to tow anything. Then, even with light loads (less than 3k lbs), it becomes the most sluggish thing you've ever seen, barely climbing the smallest of inclines without shifting to second and turning half a million RPMs. This wouldn't be a problem, but I pull quite a lot and I live in the Appalachian and it's far from flat here.
Here is my plan as of right now and I'd like feedback. I don't want much boost, just enough to give it a little kick. I'm thinking 3-5 lbs. Maybe run it at 3 and kick it up to 5 when I am pulling, supplied by either a Garrett t3 or t4 turbo. That would be coupled behind a set of P38 shorty headers (will these fit a Disco?), 2.5" pipe all the way, no cats, and back to my Borla muffler, and then dumped out in front of either side in front of the wheels. Intake piping would run from a custom snorkel, down to the turbo, to an intercooler, then up to the MAF and into the throttle body. Id like to leave all the stock electronics for simplicity sake and maybe throw in some 24 lb injectors. Then go to an electric water pump to get more consistent and higher flow speed, a full size chevy truck radiator, and dual high flow electric fans with an in line thermostat mod to keep everything running nice and cool.
Thanks for any feedback you all have.
I want to turbo my 4.6. Right now it has a Kent H180 cam, Rhoads lifters, Port and polish, intake, and exhaust. It runs like a top and I love driving it. Until I have to tow anything. Then, even with light loads (less than 3k lbs), it becomes the most sluggish thing you've ever seen, barely climbing the smallest of inclines without shifting to second and turning half a million RPMs. This wouldn't be a problem, but I pull quite a lot and I live in the Appalachian and it's far from flat here.
Here is my plan as of right now and I'd like feedback. I don't want much boost, just enough to give it a little kick. I'm thinking 3-5 lbs. Maybe run it at 3 and kick it up to 5 when I am pulling, supplied by either a Garrett t3 or t4 turbo. That would be coupled behind a set of P38 shorty headers (will these fit a Disco?), 2.5" pipe all the way, no cats, and back to my Borla muffler, and then dumped out in front of either side in front of the wheels. Intake piping would run from a custom snorkel, down to the turbo, to an intercooler, then up to the MAF and into the throttle body. Id like to leave all the stock electronics for simplicity sake and maybe throw in some 24 lb injectors. Then go to an electric water pump to get more consistent and higher flow speed, a full size chevy truck radiator, and dual high flow electric fans with an in line thermostat mod to keep everything running nice and cool.
Thanks for any feedback you all have.
#23
07-16-2015, 07:50 PM
Knew it was coming, suprised we got 3 pages in before it was mentioned.
I understand that's a risk, but to be honest I just don't believe it's as big as its made out to be. Especially not at such a small amount of boost. A naturally aspirated engine is constantly running at approx 14.7 lbs, so an additional 5 lbs (less than 1/3) shouldn't be too much extra strain on the engine. That said, if I'm wrong I'll admit defeat and just throw in a 5.3 Chevy.
I understand that's a risk, but to be honest I just don't believe it's as big as its made out to be. Especially not at such a small amount of boost. A naturally aspirated engine is constantly running at approx 14.7 lbs, so an additional 5 lbs (less than 1/3) shouldn't be too much extra strain on the engine. That said, if I'm wrong I'll admit defeat and just throw in a 5.3 Chevy.
#25
07-18-2015, 04:32 PM
#26
07-18-2015, 07:18 PM
Three Wheeling
Join Date: Dec 2012
Location: Whitecourt Alberta Canada
Posts: 78
Likes: 0
Received 2 Likes
on
2 Posts
????
Knew it was coming, suprised we got 3 pages in before it was mentioned.
I understand that's a risk, but to be honest I just don't believe it's as big as its made out to be. Especially not at such a small amount of boost. A naturally aspirated engine is constantly running at approx 14.7 lbs, so an additional 5 lbs (less than 1/3) shouldn't be too much extra strain on the engine. That said, if I'm wrong I'll admit defeat and just throw in a 5.3 Chevy.
I understand that's a risk, but to be honest I just don't believe it's as big as its made out to be. Especially not at such a small amount of boost. A naturally aspirated engine is constantly running at approx 14.7 lbs, so an additional 5 lbs (less than 1/3) shouldn't be too much extra strain on the engine. That said, if I'm wrong I'll admit defeat and just throw in a 5.3 Chevy.
Just checking.
#27
07-18-2015, 08:08 PM
Common misconception. It's 14.7:1 Air to fuel ratioil otherwise known as the stoichiometric ratio for gasoline. All he wants to do is increase the ratio of air to fuel. Increase the ratio , more power
#28
07-18-2015, 08:36 PM
Recovery Vehicle
Actually he is talking about ambient pressure. 14.7 PSI at sea level. 5 psi more is 33 % increase in air pressure leading to greater volumetric efficiency. See engines run by decreasing pressure in the cylinders so that air rushes in. When you put a higher pressure on the outside you can get a larger VOLUME of air into the cylinder, then you can clean burn a larger amount of fuel. Turbocharging is not a death sentence, you are just making the engine more efficient.
#29
07-18-2015, 08:38 PM
Edit: Looks like myself and Rover Master Mechanic answered at the same time.
Last edited by Alex_M; 07-18-2015 at 08:43 PM.
#30
07-18-2015, 08:52 PM
Close. With a turbo you actually keep the stoichiometric ratio. If you increased (or more correctly, decreased) from 14.7:1 you would be running lean and melt the pistons. When you turbo, you also have to increase your fuel output.