Offroad-Express

has anyone on here done this?, i have a spare cherokee that i want to make go better for mud drags and just playing around with, its not my usual cherokee that i use for my 4x4ing so not worried about fuel consumption or anything like that, i have both a td05 turbo off an evo and a supercharger off a yanky thunderbird, the fabrication part is not an issue as i will be doing all myself, only looking at 6-8 psi at this stage .the jeep is already stripped down and has no roof just a cage ,bigger injectors and a rising rate fuel regulater will do for a start otherwise ive got a megasquirt ecu i could use,

normally i would say I'm not sure that a turbo for a 2 litre will be ideal for a 4 litre motor, however, i guess it will spool real early so you have low down torque, and at 6-8 psi you won't ouflow the power potential of that turbo anyway( I have seen 260rwkW from one on a maxed out evo). Might need to port the wastegate to help control boost though, as 4 litres gives a big volume of exhaust gas(which will make the turbo produce more boost, unless you can divert it through the wastegate first.)
one advantage of the supercharger is less heat.(everywhere)

I suspect you could probably get about the same power from each unit assuming the supercharger is an Eaton M90. The supercharger will give you good throttle response when compared to the turbo but it will be harder to tweak as more boost will require a different pulley. Installation will probably be harder with the supercharger as well.
In saying that good throttle response would benefit off roading.

fit both, i dare ya.

we all thought it.
Crash said it!

BlakeNZ wrote:normally i would say I'm not sure that a turbo for a 2 litre will be ideal for a 4 litre motor, however, i guess it will spool real early so you have low down torque, and at 6-8 psi you won't ouflow the power potential of that turbo anyway( I have seen 260rwkW from one on a maxed out evo). Might need to port the wastegate to help control boost though, as 4 litres gives a big volume of exhaust gas(which will make the turbo produce more boost, unless you can divert it through the wastegate first.)
one advantage of the supercharger is less heat.(everywhere)

The exh housing will be way to small for a 4l engine and will just end up choking it

i agree, so if he wants to try running it, he has to stay low boost and big wastegate.

did think that about the turbo,now that youve confirmed my thoughts ,ill go looking for a bigger one, the blower is a m62, so designed for 2.5-4litre.came off a 3.8,i myself prefer the turbo option mainly for the sound and a bit easier to fit, ive got a few intercoolers to pick from,ill see what i can find next week for a turbo , cheers for that

You could always run a pair of small turbos

I've always thought the a 200hp 2.0l will flow about the same amount of exhaust gas as a 200hp 4.0l engine so you would use the same turbo for each?

Correct me if I'm wrong as I've never had experience with swaping turbos.

churchill wrote:I've always thought the a 200hp 2.0l will flow about the same amount of exhaust gas as a 200hp 4.0l engine so you would use the same turbo for each?

Correct me if I'm wrong as I've never had experience with swaping turbos.

Think you need to look at it mathmatically.

Dont know each engines rpm to hp output
So just working on a std 4000rpm for each motor

4000rpm/2 = 2000×2 ltr= 4000 ltrs of air per minute

4000rpm/2 = 2000rpm ×4ltr = 8000 ltrs or air per minute

So running the 4ltr at 2grand it would then flow similar to the 2ltr at 4grand which would make the 4ltr quite tourqey but could well run out of puff at higher revs

Altho if the 2ltr was designed to rev to 8grand then it may well slot onto the 4ltr motor quite confortabley

Again its all to do with air flow and engine air consumtion.

Fuel is a seperate issue as bigger jets and higher flow/pressure pumps will sort that out

But if you want to create 200hp in each engine you would need to inject the same amount of air and fuel assuming the same thermal efficiency and 14.7:1 fuel air ratio? You would just need no boost on the 4.0l and boost on the 2.0l to get to that 200hp?
I see where you are coming from in terms of air in but if both engines are the same design the 4.0l would just make twice as much power as the 2.0l at the same rpm.

churchill wrote:But if you want to create 200hp in each engine you would need to inject the same amount of air and fuel assuming the same thermal efficiency and 14.7:1 fuel air ratio? You would just need no boost on the 4.0l and boost on the 2.0l to get to that 200hp?
I see where you are coming from in terms of air in but if both engines are the same design the 4.0l would just make twice as much power as the 2.0l at the same rpm.

mudlva wrote:

churchill wrote:I've always thought the a 200hp 2.0l will flow about the same amount of exhaust gas as a 200hp 4.0l engine so you would use the same turbo for each?

Correct me if I'm wrong as I've never had experience with swaping turbos.

Think you need to look at it mathmatically.

Dont know each engines rpm to hp output
So just working on a std 4000rpm for each motor

4000rpm/2 = 2000×2 ltr= 4000 ltrs of air per minute

4000rpm/2 = 2000rpm ×4ltr = 8000 ltrs or air per minute

So running the 4ltr at 2grand it would then flow similar to the 2ltr at 4grand which would make the 4ltr quite tourqey but could well run out of puff at higher revs





WOW both of you guys are correct. but add this to the mix.
a NA motor is running under vacume, say a good motor is running at say 85% of 0 or 1 bar or atmosphere.

so there is the first 15% of power

secondly. the smaller motor a 2ltr to produce 200hp will need more than twice the boost than say a larger motor 4ltr. so for arguments sake, a 4ltr at 6psi = 200 hp, where a 2 ltr would only produce 150hp at 12psi boost and would more than likely need 30 psi boost.

there are two reasons for this. pressure multiply heat, linearly and then there is the mechanical induced heat, turbine sheer etc, that's why we have inter-coolers.

the second, rule of thumb, if boost pressure is at 15 psi, then exorcist pressure will be at 30 psi. or just a hell of a lot higher.
in the combustion chamber the inlet pressure must overcome the exorst pressure. simple to work out with a diesel as there is no valve over lap. but harder with a petrol.
thats why on NA motors we fit header pipes. but with a turbo it has the opposite effect.

so that's where both the above two arguments are correct but incorrect, logical but lacking information thus wrong.

there is more to consider than just what i have written. but i hate typing

Sorry, so off topic.

I think I get it. Because the boost will be higher in the smaller engine the turbo will perform differently hence why you have to match the turbo compressor maps to the flow and boost you are running. Suppose the same goes for the exhaust side of things as well.

churchill wrote:Sorry, so off topic.

I think I get it. Because the boost will be higher in the smaller engine the turbo will perform differently hence why you have to match the turbo compressor maps to the flow and boost you are running. Suppose the same goes for the exhaust side of things as well.

yes snap.

i like the Clarkson explanation.

look both posters posted logical and factual arguments, but they were incomplete. having said that if the two posters can figger out as much as they have posted they are more than capable of understanding more.
so you need to do some ground work first

look for a air temp / pressure / displacement chart
and understanding of the middle ages Monk named Joule work = heat = energy
and a good understanding of cavitation, as in boats , propellers. and every movie you have seen of a submarine.

after that, which is quite easy, every thing else slops into place

if you want to go hard, mud is all reves so think of this Garrett GTX3582R

or a hypergear ATR45

but realy on a budget and not wanting to pop every thing else in the drive train, look at an ebay job. ..6 - .65 AR

85County wrote:

churchill wrote:Sorry, so off topic.

I think I get it. Because the boost will be higher in the smaller engine the turbo will perform differently hence why you have to match the turbo compressor maps to the flow and boost you are running. Suppose the same goes for the exhaust side of things as well.

yes snap.

i like the Clarkson explanation.

look both posters posted logical and factual arguments, but they were incomplete. having said that if the two posters can figger out as much as they have posted they are more than capable of understanding more.
so you need to do some ground work first

Chillax.