Hi 380heads,

Wondering if anyone is keen to give me a closer look at the inlet manifold - notably whether the 3.8 shares the plenum of the 3.5 & 3.0. The lower inlet manifold looks remarkably similar to the 3.5s offset one (the 3.0 is different to the 3.5). Keen to see a gasket or otherwise.

Here's hoping my soon to be developed replacement manifold can be adapted to the 380 with similar gains to the magna.

Thanks in advance. :cool:

Here's hoping my soon to be developed replacement manifold can be adapted to the 380 with similar gains to the magna.


Hey EZ,

Great to see you in here, pimpin the new EZi Breather (for the heavy breathers!) :P lol

If it enhances the low to midrange on the G75 as well, we are truly going to have a torque monster :cool:

I'm hoping the top end will benefit as well. If you look at the engine graphs (NZ Intake thread) the midrange has dominance and the top end is well and truly throttled. Torque drops off very suddenly after 4000rpm; doesn't look normal compared to the G74 and on the road I can really feel it. Waste of time taking the revs past 5000rpm, engine thrashing away not giving any extra torque and feels flat. Considering the Ralliart cams and roller rockers that's frustrating :confused: .

Problems might be a bit more complex with EGR or whatever arrangement it is now, clearance with the strut brace and cruise control. I found researching the exhaust that there are a lot of sensors that need to stay for the engine management, but anything can be overcome.

I probably can't help you here in Brisvegas, might be other members close to Newcastle?

If it enhances the low to midrange on the G75 as well, we are truly going to have a torque monster :cool:

I'm hoping the top end will benefit as well. If you look at the engine graphs (NZ Intake thread) the midrange has dominance and the top end is well and truly throttled. Torque drops off very suddenly after 4000rpm; doesn't look normal compared to the G74 and on the road I can really feel it. Waste of time taking the revs past 5000rpm, engine thrashing away not giving any extra torque and feels flat. Considering the Ralliart cams and roller rockers that's frustrating :confused:

Not wanting to chase low rpm with sacrifice to mid and top as the current trialled concept of the manifold. Low rpm is hard to change on the Magna due to stroke:bore and cam profile. The 3.8L is obviously a stroked 6G74 and hence aquires more low rpm torque. The downside is the higher piston speeds as rpm increase and the battle to make useable power efficiently with high component speeds increasing friction and decreasing efficiency at those rpm. The motor was of course designed to have low rpm torque and hence better fuel economy. If the manifold replacement can maintain the current low rpm torque or enuf of it to not be missed BUT allow the motor to pull harder longer then the peak power figure of 175wm can be increased. I think it would crack 200 with a manifold and breathing mods as well as extractors. The 2x oxy sensors in each of the exhaust headers can still be retained - they're there to measure the ratio of combustion byproducts so why would the ratio in a single runner in an extractor manifold be difference to the collector of the oem manifold? Beside obvious engineering deficiencies and other sacrifices of economy - but you know what I'm getting at....


Brisvegas

Good onya! lol

I think it would crack 200 with a manifold and breathing mods as well as extractors.

I have a feeling you're right. I'd say part of the sharp drop off in torque up-top in the 6G75 is the restrictive exhuast system.

The 3.8L is obviously a stroked 6G74 and hence aquires more low rpm torque. The downside is the higher piston speeds as rpm increase and the battle to make useable power efficiently with high component speeds increasing friction and decreasing efficiency at those rpm. The motor was of course designed to have low rpm torque and hence better fuel economy.

Yep, hear what your saying re the characteristics of long stroke versus a more square design. Having a look at the comparison-

Bore × Stroke

G75;
95.0 × 90.0

G74;
93.0 × 85.8

Some other engines;

Ford BA -
92.3 x 99.3

VE -
94 x 85.6

The BA has a very long stroke design but has been very successful with reviewers not noting any shortfall in the upper rev range - twin cam head would help tho.
But the G75 has the hardware to breathe in the upper range; roller rockers, good cam and 12 hole injectors.
So, hopefully we can get to the point where the G75 will feel as free revving as the G74 with strength from low to high rev ranges.
In fact, thinking about it, the G75 does rev quite well high up - it just doesn't feel like it's making any real power whereas the 3.5 feels strongest in the rev range from 3500 upwards.

As you say, everything about breathing needs to be improved to see what power is really available.

Yep, hear what your saying re the characteristics of long stroke versus a more square design.
The BA has a very long stroke design but has been very successful with reviewers not noting any shortfall in the upper rev range - twin cam head would help tho.


Well personally when I drove a rental BA XT, I found the top-end quite strangled feeling, it become quite harsh and felt flat over 5000 rpm.

To me it seems you don't hear about complaints from reviewers regarding this, because for a motor with such strong bottom-end and midrange, you'd expect the top-end to be lacking. The Ford I6 is regarded as a "workhorse" motor, not a "fun" free-revving motor, so I don't think it running out of revs is generally considered much of an issue.

Then again, maybe I just had a trashed rental car.

Fair enough. Nice to see you in here Chisholm.

Looking at the 6G75 tho it doesn't look an overly long stroke compared to bore so I'm hoping there is still a reasonable top end to liberate. If not, so be it, a solid midrange is more desirable for the road.

Looking at the 6G75 tho it doesn't look an overly long stroke compared to bore so I'm hoping there is still a reasonable top end to liberate. If not, so be it, a solid midrange is more desirable for the road.

I can almost guarantee there would be a fair amount of top end potential. Now obviously the engine will not like to be revved too far, but I'd imagine the current breathing restrictions are playing the bigger part in the lack of top end then the bore to stroke ratio.

It will be interesting to see what can be done with the 6G75 once more people start playing with it, my feeling is there's quite a bit of potential there.

The 10:1 compression ratio and larger capacity is a big help, in that you should be able to run a relatively agressive cam in there without losing driveability or needing to swap pistons - which brings down the price of extracting decent power greatly.

its more cubic inches and not too long in the stroke. should have good potential, just need to spin it a little faster with the right cams.

disappointing that the TMR380 barely made more power than s/c 6G74.

its more cubic inches and not too long in the stroke. should have good potential, just need to spin it a little faster with the right cams.
disappointing that the TMR380 barely made more power than s/c 6G74.

I agree. The Ralliart Magna made 180kW with it's cams on a 3.5, it'd be safe to say that they now might be adding to a restriction uptop on the larger 6G75, since we are trying to draw in a larger volume of air/fuel (0.3 increase in capacity) at a faster rate (longer stroke, larger bore) through the same amount of lift.

Free up the breathing, and slap a cam in there, and I'd be surprised if you didn't see significant gains.

Force the air in it'll rev out easily then, mine revs like **** now