Hay all

Ive done just about everything now to my magna N/A that i wont to do. Only thing i can think of is a RPW manifold ive read through some old threads i mean old and read some good things about them im just wanting some other peoples opinions in this as im getting it tuned after this last mod if i get some good feedback. But yeah peoples let me now wat you think.?

Thanks Kurt

You dared to mention RPW... prepare yourself for comments like it doesn't do anything, it actually looses power & so on.....

From personal experience i got second hand RPW manifold for $300 & yes it did give me some early torque (at least thats how it felt), dont know if it robbed any top end, but my 4 speed auto definitely felt better down low. That said you'd be pretty disappointed if you had to pay $1200 for it, hey thats a price for brand new LSD(i believe this is what they ask for it), $$$ spent makes no sense for the gain you get, so try to look around for second hand unit......

Alright. Wat are other peoples thoughts on other mods or mod i could do before my tune?

Not much buddy. Unless you have alot of money to spend.

have you got a hi flow metal cat?
to do some serious tuning (will probably cost around 800 for the amount of dyno time) get some adjustable cam sprokets.
also, im not sure of the way that the place your going to can do it, but maybey some 380 injectors. not because they are bigger, but because they have more holes, for better fuel injection characteristics. (if the tw engine already had these, dont worry about it.

would it matter if the 380 injectors were installed after the tune? or would the larger cc's change the A/F mix? because when tuned its based off duty cycle

would it matter if the 380 injectors were installed after the tune? or would the larger cc's change the A/F mix? because when tuned its based off duty cycle

Won't matter at all. The flow rate is actually the same; they've just got a different spray pattern. (I'm actually running 1 3.5l injector on my 3.8l as I'm too tight to pay for a new one to replace a dud 3.8l one!)

im am not 100% certain but i think it does matter. with a bigger injector, with a higher flow rate running for the same time as a small less flowy injector,it would matter. when i put 3 380 injectors in my car, and 3 standard ones it wouldnt rev past 5500. it does make a difference, but im not sure how much.

380 injector are 305cc VS 275cc for 3.5 litre, so obviously the flow is about 10% better, its never a good idea to mix injectors. Given that ECU doesn't not know that only one cylinder (or lets say 3) has 275cc which would need slightly higher duty cycle to keep up with 300cc. So you will end up with slightly leaner mixture in affected cylinders.

Please correct me if im wrong, ECU will try ti fix the problem & will increase duty cycle but then you end up with cylinders that are running 305cc injectors having richer mixture then 275cc in order to compensate. ECU can not know which cylinder is running lean or rich, it can only tell overall. So it will not adjust duty cycle for one injector only it will do it for all of them & if you have different flow rates on injectors you will always end up with unbalanced AFR ratios in cylinders

380 injector are 305cc VS 275cc for 3.5 litre, so obviously the flow is about 10% better, its never a good idea to mix injectors. Given that ECU doesn't not know that only one cylinder (or lets say 3) has 275cc which would need slightly higher duty cycle to keep up with 300cc. So you will end up with slightly leaner mixture in affected cylinders.

Please correct me if im wrong, ECU will try ti fix the problem & will increase duty cycle but then you end up with cylinders that are running 305cc injectors having richer mixture then 275cc in order to compensate. ECU can not know which cylinder is running lean or rich, it can only tell overall. So it will not adjust duty cycle for one injector only it will do it for all of them & if you have different flow rates on injectors you will always end up with unbalanced AFR ratios in cylinders

The 380 injectors are the same cc flow rate as the 3.5L injectors, ive had both flow tested and they came back within a few cc's of each other at 3 bar test pressure. Ive also had both types of injectors in my magna, in the same engine and both ran the same AFR's back to back (hence why my car leaned out so much and the only way to compensate for it until i fitted the larger injectors was to up fuel pressure to 55psi at idleand then adjust the AFR's to stop overfuelling down low)

What do 380 injectors actually flow at?

When i had my 3.5l injectors high flowed, in factory form they were flowing 295cc (20cc above what they were supposed to)

What do 380 injectors actually flow at?

When i had my 3.5l injectors high flowed, in factory form they were flowing 295cc (20cc above what they were supposed to)

The set of 380 Injectors that i had flowed 288cc @ 3bar (44.1Psi) of pressure, The higher the test pressure the more an injector will flow (within in reason)

Not trying to offend you in any way, but are you certain they were indeed 380 injectors?

Mine were flowed at 305cc @ 3 bar before I went bigger. Seems depends who tests them what the outcome is ....

Not trying to offend you in any way, but are you certain they were indeed 380 injectors?

Sure were.... They were brand new 12hole 380 injectors from MMAL. The brand new 3.5L CDH275 4 hole injectors that i had flowed at the same time flowed 278cc @ 3 bar

As if i dont know what 380 injectors look like gees..... lol

lol no worries man, like i said no offense was intended

Sure were.... They were brand new 12hole 380 injectors from MMAL. The brand new 3.5L CDH275 4 hole injectors that i had flowed at the same time flowed 278cc @ 3 bar


Out of curiosity, what was the variation from injector to injector like for both types of injectors?

To the OP - individual TB's on each cylinder coming off the top and a custom sock filter and intake with bonnet mods. Will sound brutal.

To the OP - individual TB's on each cylinder coming off the top and a custom sock filter and intake with bonnet mods. Will sound brutal.

For the amount of money needed to get that setup he could get better mods like high flow heads and cams. Much better than an intake mod

Would a set of 380 heads do that.
I don't know for sure, but do 380 heads have 25% better flow than Magna heads?
Comes with roller rockers, amd quite possibly injectors as well.

roller rockers were on the magna heads too

Would a set of 380 heads do that.
I don't know for sure, but do 380 heads have 25% better flow than Magna heads?
Comes with roller rockers, amd quite possibly injectors as well.

3.8L heads on a 3.5L bottom end would drop the compression by a fair amount, due to the 3.8L heads combustion chamber having a larger volume compared to the 3.5L combustion chamber, so to get the compression back up would require a piston change..... easier (and cheaper) to just do a full 3.8L conversion.

the 3.5L magnas had roller rockers from factory as well.

Once you start talking about work inside the engine, really $$$ spent hardly worth it, unless you do everything, like pistons, heads but then expect to spend about $4000

Just to give you an idea, just to take your heads of & rebuilt them to factory level you are looking at about $700, thats given you take heads of yourself. Once you start adding things like oversized & ported valves, shaving heads to raise compression, new valve springs. you would be looking at about $1800 & you haven't even touched pistons or cams yet.

As mentioned above 380 engine is probably best value N/A upgrade you can go, if you start taking about working the actual engine. But given you already have 380 cams again its hardly worth it

Back to OP's topic. You ve pretty much done everything i can think of, without going into ridiculous spending spree for small gains. Like i said before intake manifold is a good thing but i would not justify spending $1200 on it. You are a bit late, i just sold mine few weeks ago since i had no use for it due to sprintex supercharger.

3.8L heads on a 3.5L bottom end would drop the compression by a fair amount, due to the 3.8L heads combustion chamber having a larger volume compared to the 3.5L combustion chamber, so to get the compression back up would require a piston change..... easier (and cheaper) to just do a full 3.8L conversion.

the 3.5L magnas had roller rockers from factory as well.

How would this fair up in a boosted application, would it allow you to run higher levels of boost safely?

I fitted a RPW modified manifold to my Ralliart and had it dynoed before and after.
Result: an increase of about 2hp midrange with no change at top end.
Why didn't I return it? Because it was originaly fitted to my TJ Exec for a couple of years before buying the Ralliart.
Yet the RPW ad claimed large increases in power/ torque (on their twin turbo Magna).
What a waste of $1000 and disappointment.

I fitted a RPW modified manifold to my Ralliart and had it dynoed before and after.
Result: an increase of about 2hp midrange with no change at top end.
Why didn't I return it? Because it was originaly fitted to my TJ Exec for a couple of years before buying the Ralliart.
Yet the RPW ad claimed large increases in power/ torque (on their twin turbo Magna).
What a waste of $1000 and disappointment.

Well the letters RPW says it all...... Say no more.

I fitted a RPW modified manifold to my Ralliart and had it dynoed before and after.
Result: an increase of about 2hp midrange with no change at top end.
Why didn't I return it? Because it was originaly fitted to my TJ Exec for a couple of years before buying the Ralliart.
Yet the RPW ad claimed large increases in power/ torque (on their twin turbo Magna).
What a waste of $1000 and disappointment.


Got to agree, i just bought Andrei1984's manifold as mentioned above and from o nthe road driving, can't really tell the difference although there may be some other benefits, thankfully i didn't pay $1200 for it !!

So is it beneficial at all to fit 380 injectors ?

For the amount of money needed to get that setup he could get better mods like high flow heads and cams. Much better than an intake mod

high flow heads and cams would be needed first - just an FYI, properly set up individual TB's on a strengthened engine and you can get forced induction levels of power. 250+kW should be achievable on a 3.5 V6

high flow heads and cams would be needed first - just an FYI, properly set up individual TB's on a strengthened engine and you can get forced induction levels of power. 250+kW should be achievable on a 3.5 V6

Mines pushing 242kw atw with a stock bottom end and headwork, valves, vlave springs. Adjustable cam gears+ other bits and the sc