put a down draft intake on 300 promax

[demag67]

I am going through my motors right now and was thinking about going to a down draft intake on them. they are 98 300 promax's, what would be involved in the swap and could I use one from a 225 or 250 3l? Would it benefit me at all with it on. not looking to raise compression and I don't want to spin them up over 6200 so not sure if it would be worth it. thanks

[NICE PAIR]

Look up Shaun Torrente Racing/Florida I think.

[Nick225EFI]

Simon Motorsports used to offer a conversion for this and there was one of his for sale on here recently by hydrostream1, if I recall. He had a 300PM and the intake up for sale, not sure if it was sold or not.

[demag67]

no go on simon or shaun.

[Nick225EFI]

http://www.screamandfly.com/showthre...4295-99-300-pm
This is the thread for his 300PM sale, the engine did sell, but it didnt mention the sale of the intake. Drop him a line and see if he still has the intake.

[demag67]

Nick thanks for the reply. Gonna hit him up and see. Thanks

[Lake rat Skater]

Anything ever come of this? I'm curious if any has experience with a downdraft on a 300 promax.

[Chaz]

Still working on a better, less expensive billet piece for 2020 :

[malexie]

Don't do it. Even if you want to increase HP the XRI front works great.

[Chaz]

Don't do it. Even if you want to increase HP the XRI front works great.

XRI .... emm, you do know this a three litre ... right ?
But then, you could call it a "Lazer" .. and still be right .. I recon ..

The four butterfly (antique) has :

More sq/in of butterfly area than the downdraft ...

However, the air must make its way around the VST on the port side and the starter on the starboard side, go in the backside, make a 180* U-turn, fight thru the fuel rail, injectors, injector boss, hoses and wires and then find a butterfly to pass thru.

With all that, the air sees something like this ...



With a view like this, no wonder the 300x made 30 more mules than the 300pm it replaced. Putting a downdraft on an early model will get you most of that. The rest is in the exhaust log.

A few reasons I like the late model EFI's :

The Motorolla that replaced the two pancakes.

No harness modifications, late model to external injector set-up, is plug and play.

Electric oil pump driver ( no stripped plastic gear)

Both heads have temp sensors, instead of one.

Water pressure warning.

No stator.

Six injector drivers, instead of three. Since the twins batch fire two cylinders at a time on a 60* split. Which bank off, one side, the other .. or a little of both ?

Air is pulled into the cawl, then up and over the flywheel area and down the throttle body. The only downside I see to this is that heat rises and that's the path.

The plenum area of the downdraft is aprox 215 ci. The motor is 187 ish. Being oversquare it tends to slow air collum down, providing a bit of "still air box" to pull from instead of a hurricane. With parts out there to do the swap, no need to go over the hill - and thru the woods - to the reed blocks we go ..

Looks to be more of a straight shot to me ...

[malexie]

He did ask if it's worth it. At 6200 rpm's leave it alone. Now if he wants 9200 rpm's I would straighten out the air even more.

[Capt.Insane-o]

Dunno, I installed a handful of 3 lite svs on bass and checkmate type boats. The gains over the box were impressive even on stock limiters. Wish they were still available readily, I could probably do another 5-6 more.

[powerabout]

Hi Chaz
6 injector drivers means sequential injection or not?

[Chaz]

He did ask if it's worth it. At 6200 rpm's leave it alone. Now if he wants 9200 rpm's I would straighten out the air even more.

The downdraft is 30-35 HP better, OP has two .. so if you want to throw away 60-70 HP, using mostly parts off of the junk pile or E-bay, be my guest ...

When you buzz a 3.0 or 3.2 up to 9200 RPM ... do me a quid-pro-quo and shoot a video of it ...

Capt.Insane-o

Dunno, I installed a handful of 3 lite svs on bass and checkmate type boats. The gains over the box were impressive even on stock limiters. Wish they were still available readily, I could probably do another 5-6 more.

If you can stand to lose the "street manors" and make the necessary changes to the fuel curve to match the air volume @ mid throttle, then you can count on one hand the diff between a slide and my favorite of all, the E-tec front that sports an open plenum and a butterfly in front of each pair of reed blocks .. and none of the bad traits of I.R. intakes.

https://www.facebook.com/26293773058...4706700738700/

https://www.facebook.com/26293773058...3846748531541/

powerabout

Hi Chaz
6 injector drivers means sequential injection or not?

Yeeaasssssssssssssss ............

[Capt.Insane-o]

Yes the slides have a learning curve post tip in and lower mid range, stabby stabby and choppy choppy throttle doers had a few surprises lol