Backwards Air Scoops ??

[MidnightMantra]

Ok people fill me in here. I am finishing up my very first jet boat and should have it water ready in another two weeks. I baught an Dooley Type Air Scoop and was wondering why some people have them mounted on thier engines backwards? With them facing foreward do they catch to much air? What is the reason behind them facing to the back?

[RiverToysJas]

You don't have to have any sort of flame arrester if they face backwards, and they don't catch any water. ;)
RTJas :D

[fourspeednup]

Same reasons as stated above and...
Once you get going real fast(around 95 I think), those types of scoops start messing with the vacuum signal to the carbs because of all the air passing over the top.
There was a thread on HBJet's ride with that topic:cool:

[TRG]

you kno...i was noticing the other day...most olds motors that ive seen in the past seem to all run with them backwards more so than CHEVY or F@R*$, could this have something to do with the desing of the olds or just a figment of my imagination? lol

[MidnightMantra]

Well thanks for the input, I guess it's just going to have to be trial and error thing. Don't think my boat is going to reach 95 gps though. I am running a conservative 468Ci Roller @ 650hp, desktop says 749hp in a 18' mantra with a early style dominator pump "A" cut impeller. The Engine in my race car pulled to 7500 rpm's at the shift which now that engine is freshened up and in my boat. I have set the limiter for 6500 rpm's for the boat. My first jet boat, first test run in two weeks after I get my Banderlog Valve in thats on back order. What kind of speeds do you think I will see? Hull is semi-v. Picture of boat with old stock 454 enclosed

[MudPumper]

Are you running a loader, shoe and rideplate with that setup?????
And what kind of impeller, Al, Bronze or SS???

[Taylorman]

Originally posted by toddnjuzz
you kno...i was noticing the other day...most olds motors that ive seen in the past seem to all run with them backwards more so than CHEVY or F@R*$, could this have something to do with the desing of the olds or just a figment of my imagination? lol
Yep its a figment of your imagination. No dissing on the Olds guys. Running them backwards may have its purpose but it sure does look gay. If your running it that way for the backfire reason, buy a flame arrestor, they are only $25.

[TRG]

actually taylorman, i was getting to the point(but left it out of the story, lol) that a couple of buddies run the 455 and the motors run much better with the scoops turned around, like between 1-300 rpm diff. i tried to do the same with my BBC and the motor did not like the adjustment!

[Taylorman]

Really!! Why is that?:confused:

[Ken F]

Not to burst your bubble at all, but having a jet pump hooked to the back of your engine is like having it bolted to a
dyno. You probably aren't going to see 6k rpm with an A impeller. It'll run, but you probably aren't going to get into peak power on your cam if it's still the one you had in your race car.
However...take it out and run it, have fun with it and see what it does! then you will begin to understand what needs to be different on a boat engine..
Ken F

[TRG]

i truly do not know why!
can you enlighten me?:confused:

[Taylorman]

Im not trying to be an ass. I truely don't know and was asking you.

[TRG]

to fu@#ing funny,...were like the blind leading the blind!! lmfao
i never took it that way!
its funny how we as typists mean one thing and it get misconstrewed as another!:D
if you come up with an answer,... help a brutha out!
todd

[MudPumper]

I think the answer you are looking for guys is.........Because Chevy's kick ass and Olds suck ass!!!!!
Mud<Hoping you guys don't have an Olds :confused: >Pumper
:D

[TRG]

thats funny too!!

[DeltaSigBoater]

Originally posted by MudPumper
I think the answer you are looking for guys is.........Because Chevy's kick ass and Olds suck ass!!!!!
Mud<Hoping you guys don't have an Olds :confused: >Pumper
:D
A couple of years ago I was at a boat swap meet and this guy had a set of un-used log exhaust manifolds with risers, gaskets, & bolts. I asked the guy how much & he said $200 for everything.
“These are for a 455 Olds, huh?” I said.
“Yeah, how’d you know that?” the guy said.
“If they were for a Ford or Chevy you’d be asking way more than $200.”

[Taylorman]

Originally posted by MudPumper
I think the answer you are looking for guys is.........Because Chevy's kick ass and Olds suck ass!!!!!
Mud<Hoping you guys don't have an Olds :confused: >Pumper
:D
Hey, how fast is your boat with that pretty Chevy?
I agree and Olds is not a Chevy but im keeping my Olds because of sentamental value. My dad owned it for years and i learned to ski behind this boat. Besides, my hull (Taylor SJ) is not make for speed. Im trying to get it to 70 and I'll be happy.

[Nucking futs]

Well i also had the very same experiance with the scoop on an olds. it ran 300-500 rpms more with it backwards.Second,the olds we had no one could beat for 2 yrs straight in ndba river racer class.so i cant bad mouth them but i love my cheby.oh and for the people who want to know what boat,mike stamps war horse,19ft southwind tunnel dragster.put the same engine in a cal. perf. hull and it went even faster,hate to say that cuz i am a southwind owner/operator!!!:cool: