Rpm

« **on:** June 23, 2014, 07:02:58 PM »

Got a chance to put those Demon 1904 750 carbs on my boat. Instantly the boat idled and a little more adjustment it was ready for the lake. On the lake the boat runs great!!! Pin the throttle on the boat without the nitrous and I'm only getting 5200 rpm max. The boat is easily doing 70 plus no problems there. I guess my question is with the jet built correctly with your engine hrspwr is it normal to be running that low of rpm? I estimate my engine to be between 500-550 hspr without the bottle.

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« **Reply #1 on:** June 23, 2014, 07:17:49 PM »

What impeller?

« **Reply #2 on:** June 23, 2014, 07:19:40 PM »

5200 seems a little low for 70, was that on a GPS?

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« **Reply #3 on:** June 23, 2014, 07:20:25 PM »

And why does it take 2 750s to make 500hp?

And why does it take nitrous to do better than 70mph?

What's your engine combo? Unless you've got a barge...sumthang ain't right.

« **Reply #4 on:** June 23, 2014, 07:40:39 PM »

Nitrous a side haven't used it yet. I'm still tuning the engine so I can use it. I'm not sure what impeller it is bought the boat with the pump in it. The guy who had it before me had a 496 in the boat. As for the carbs I had two edelbrock 650s that wouldn't idle for anything. I decided to go with the 750's on the recommendation from the guys at Mondello. Plus they supply better vacuum. I'm running a 455 olds with Edelbrock rpm aluminum heads, dual quad tunnel ram, forged speed pro pistons at about 9.5 compression and a few other upgrades such as ignition and oil pan. The pump has a droop and a loader grate along with a place diverter. I thought the rpm was a little low but the boat runs fast and no hesitation. Thought it might be the rev limiter on the Mallory 6al box but on the trailer I can get it to rev way past 5200 rpm.

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« **Reply #5 on:** June 23, 2014, 07:50:36 PM »

Wtf are those cans over the carbs inside the scoop?

« **Reply #6 on:** June 23, 2014, 07:51:20 PM »

What kind of hull is that..looks bieser-ish

« **Reply #7 on:** June 23, 2014, 07:51:55 PM »

Find out what impeller you have in there. That will tell you why your not spinning that thing past 5200. Nitrous on a 455?

🙀🙀🙀🙀🙀🙀🙀

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« **Reply #8 on:** June 23, 2014, 07:52:55 PM »

Lol they are just carb covers for when it's stored so nothing gets down into the engine. It's a 75 hornet.

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« **Reply #9 on:** June 23, 2014, 07:53:00 PM »

And get of those PCV hoses...huge vacuum leak. Run 'em into a puke tank or the headers.

« **Reply #10 on:** June 23, 2014, 07:53:44 PM »

Does the dash have glassed in angled gage bezels?

« **Reply #11 on:** June 23, 2014, 07:53:56 PM »

Quote from: jyeager on June 23, 2014, 07:51:55 PM

Find out what impeller you have in there. That will tell you why your not spinning that thing past 5200.

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Is there an easy way to finding out without taring the whole pump a part?

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« **Reply #12 on:** June 23, 2014, 07:54:30 PM »

Angled bezels.

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« **Reply #13 on:** June 23, 2014, 07:57:11 PM »

Sorry glassed in angled is what it has.

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« **Reply #14 on:** June 23, 2014, 07:58:50 PM »

I had one of those for a couple weeks...cool boat

« **Reply #15 on:** June 23, 2014, 07:59:14 PM »

Quote from: Xthaspot on June 23, 2014, 07:53:56 PM

Is there an easy way to finding out without taring the whole pump a part?

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No. Pull the bowl and the impeller.

« **Reply #16 on:** June 24, 2014, 09:10:25 AM »

If the pump is tight, and running 5200 r's, and an 'A' Impeller, your at ~500 hp
With a "B" impeller more like ~425 hp

70 @ 5200 is not unrealistic
My bbc ran 71.8 @ 5300 r's, gps'd at Laughlin, Nv. (460", Vic jr., 750 holley, bassetts, heavy azz hull)

Dan'l

« **Reply #17 on:** June 24, 2014, 10:09:01 AM »

Quote from: mash on it on June 24, 2014, 09:10:25 AM

If the pump is tight, and running 5200 r's, and an 'A' Impeller, your at ~500 hp
With a "B" impeller more like ~425 hp

70 @ 5200 is not unrealistic
My bbc ran 71.8 @ 5300 r's, gps'd at Laughlin, Nv. (460", Vic jr., 750 holley, bassetts, heavy azz hull)

Dan'l

Yea I'm leaning to its normal. Talked to a Berkley tech and he basically said the same thing. I am within reason and it's not unusual. Thanks for your help.

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« **Reply #18 on:** June 24, 2014, 01:10:40 PM »

Quote from: mash on it on June 24, 2014, 09:10:25 AM

70 @ 5200 is not unrealistic

Dan'l

mis read it.

X2

80 plus is not unrealistic.

GT

« **Reply #19 on:** June 24, 2014, 01:20:13 PM »

Quote from: Xthaspot on June 23, 2014, 07:02:58 PM

Got a chance to put those Demon 1904 750 carbs on my boat. Instantly the boat idled and a little more adjustment it was ready for the lake. On the lake the boat runs great!!! Pin the throttle on the boat without the nitrous and I'm only getting 5200 rpm max. The boat is easily doing 70 plus no problems there. I guess my question is with the jet built correctly with your engine hrspwr is it normal to be running that low of rpm? I estimate my engine to be between 500-550 hspr without the bottle.

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I had a 454, 425 hp...ish, 5-5200 rpm go 74 mph.
Not out of reason, but at the lower end of the spectrum for sure.

-beerjet-

« **Reply #20 on:** June 24, 2014, 06:43:34 PM »

Put a straight edge along that ride plate....let's see how much hardware you're dragging in the water. Can't tell from the pic. That looks like an old style nozzle, I bet you're dragging the reverse outlet...probably pick up 5mph or so if you chop it off..maybe more. Got any pictures of the boat running? How wet does it run?

« **Reply #21 on:** June 25, 2014, 12:31:33 AM »

Quote from: lbhsbz on June 23, 2014, 07:50:36 PM

Wtf are those cans over the carbs inside the scoop?

lol I have to laugh for you not even know what those caps are for. But anyways the boat is with in range and spec for the pump. What you are running is about right on with HP specs with the pump.

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« **Reply #22 on:** June 25, 2014, 08:09:29 AM »

Quote from: lbhsbz on June 24, 2014, 06:43:34 PM

Put a straight edge along that ride plate....let's see how much hardware you're dragging in the water. Can't tell from the pic. That looks like an old style nozzle, I bet you're dragging the reverse outlet...probably pick up 5mph or so if you chop it off..maybe more. Got any pictures of the boat running? How wet does it run?

Don't have any footage of it running in the water just out of the water. I will check that nozzle for sure. Didn't think to look at that thanks.

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« **Reply #23 on:** June 25, 2014, 09:09:51 AM »

Quote from: Bigblockchevy1691 on June 25, 2014, 12:31:33 AM

lol I have to laugh for you not even know what those caps are for. But anyways the boat is with in range and spec for the pump. What you are running is about right on with HP specs with the pump.

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I've never seen 'em, I always just stuffed a towel in the scoop

« **Reply #24 on:** June 25, 2014, 01:16:10 PM »

Them caps are nice to have and work good

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Xthaspot

lbhsbz

Riverlife_

lbhsbz

Xthaspot

lbhsbz

lbhsbz

jyeager

Xthaspot

lbhsbz

lbhsbz

Xthaspot

Xthaspot

Xthaspot

lbhsbz

lbhsbz

mash on it

Xthaspot

GT Jets

beerjet

lbhsbz

Bigblockchevy1691

Xthaspot

lbhsbz

Bigblockchevy1691