LRA Snorkel: my experiences.

[Lucus]

(As posted on Aulro, just thought i would put it here as well)



Hi Guys,
yesterday i installed a Les Richmond Autos snorkel to mmy 93rrc. Heres what i discovered.
( i am able to read all these parameters on my wolf 3d ecu screen)

Pre snorkel
Ambient 30deg c
Intake air temp (at 70 k's per hour) 65 to 70deg c
Coolant temp 95 to 99 deg c dependant on load (ie up or down hill)
AFR at 70kph cruise set 15.1:1
Vacum at W.O.T. at 70kph 20 to 25kpa.


Post snorkel:
Ambient 44(phreaking hot!!!)deg c
Intake air temp (at 70 k's per hour) 45 to 49deg c
Coolant temp 92 to 95 deg c dependant on load (ie up or down hill, remained below thermo fan cut in temp at 70kph)
AFR at 70kph cruise set 16.2:1(lots more air!)
Vacum at W.O.T. at 70kph -02 to 00kpa.

To say i am happy is an understatement. I tested the before and after runs on the same 30km route between mny house and my fiance's house.
I went 4wding today in 33deg c heat and the hottest the car got was 102deg c and that was after about a 2km slog in 3rd gear low range at 40kph in the sand. The car would normally reach 108+ doing this. I also managed to banish the dreaded pinging i had in load range at high low but i also ran octane booster so i will have to retest the car again minus the o2 booster. But the 20 deg reduction in intake air temp had got to help. Btw the car had a totally standard intake system prior to fitting the snorkel and is fitted with a 4.6ltr.

cheers
Luke

[DiscoDino]

Interesting

[RangingRover]

The fact that you had vacuum at WOT previous to installing the snorkel is interesting - WOT should be atmospheric pressure - ie. No vacuum. I wonder if the air being so hot meant it couldn't actually draw enough in with the lower density, and caused the vacuum.

You should notice a pretty big performance gain once the ambient temperatures get down below 20 degrees also, as it seems that once the air gets above about 25 degrees you start to lose a little grunt.

But the 20 deg reduction in intake air temp had got to help.

Actually, it's probably more like 30 degrees My car seems to pick up about 5 degrees over ambient just through heat held in the intake piping, but thats it - if you check your intake on another 30 degree day, you'll probably see between 35 - 40. And that definitely makes a big difference, and the ram effect at speed helps too!

[Lucus]

Does your 4.6 still run a rover round canister aif filter? I sumised the air being drawn into the housing and stricking the front of the filter before being drawn around the edges into the filter probably wouldnt help. It now has a 3.5" hole in the side that exposed alot more of the filter to the airflow.

I know the intake system is a restriction. When the car was dyno'ed last (and it still had the afm fited as i hadnt modified the intake to delete it) it pulled 2"of HG at wot. I think the intake runners are too small for a 4.6 and the plenum volume is too small. Im toying with the idea of making some 1 and 2" spacers to spacer the top half of the plenum up to increase the volume. I would also like to add and isolator (again 1 or 2") between the lower part of the plenum and the intake manifold. Im keen to see what difference the extra plenum volume and intake runner length would make to the torque of the engine. I will probably have to wait till the body lift is fitted for bonnet clearance tho.

Rangin do you have access to a video camera? i would love to see a vid of how responsive the megasquirt is when you crack the throttle wide open from idle. I get a small pause and then the revs take off. There is also a noise from the intake manifold that sounds to me like the motor starving for air then catching up with itself.

Does your car do this?

[RangingRover]

mine has the round canister with the LRA style fibreglass doohickey on the side of it. The biggest gain on mine was hoicking the AFM, as I had a flapper, and if you look up the guts of that, its about a 40mm square.

My car under load, with a standard 3.5 plenum/throttle body and somewhat ported intake manifold, 3 inch pipe between throttle body and airbox and then snorkel, doesn't show any vacuum at all under wide open throttle.

Spacing between the two halves of the intake manifold will bring the peak torque down a bit, and is one of the things that AMV do with their modified setups. It won't increase throttle response, but its something I've been meaning to do for a while to see if it goes better. As far as plenum goes, I'd remake it to be wider at the top, rather than spacing it up, that way you can put as big a spacer in the two bits of manifold as your bodylift. This may have some effect.

Re your 'starving for air' noise - without hearing it, I'd take a stab at your acceleration enrichments needing a bit of adjustment up or down. I don't recollect mine ever making that kind of noise.... That said, my quad throttled Alfa squeals through the intake under light throttle for some reason.

When you say responsive from idle, do you mean taking off, or just free revving? I don't think I really get any pause in mine when free revving, but I know that many standard 3.9s seem to do a kind of "foop" noise before they rev up, despite everything being setup correctly.

[Lucus]

Ranging, i meant free reving. "foop" pretty much sums up the noise perfectly...

[RangingRover]

Well, if you are fooping around , I'd definitely suggest playing with your acceleration enrichments to see if you can tune it out - you shouldn't have any trouble getting rid of it on your 3.9 gear, especially if you've removed your AFM - I think its mildly improved from the 3.5 gear I'm using.

From memory (haven't heard the noise for a little while), it sounds like it needs to have a bit more fuel to cope with the influx of air on harder throttle tip in. I'm pretty sure I've improved it on a stock car by richening it up a bit also. Point to note here though is that way too much accel enrichment sounds the same as too little, so if you increase it a lot and nothing happens, try going back the other way.

Other thought that occurs to me - vacuum advance? Is it connected on your car, or do you control spark? I don't have any vac advance on mine, but my ecu controls my advance curve anyway. Could be worth a fiddle.