How important is torque??

[BlueNun]

How important is torque in a jet?? I see alot of tunnell rams which I know are upper RPM pullers. I am looking at intakes and the Edelbrock AirGap looks descent for a dual plane and it pulls from 1500-5500 I think. Or should I look at the taller single plane manifolds like brodix,merlin, etc??

[pw_Tony]

I thought the RPM air gap went up to bout 6300 rpm or so?

[Sleeper CP]

Need alittle more info on the engine. How high do you want to turn the engine and what is it? What impeller are you running and what do you what to spin it too?
I've had some experience with the small block air gaps for Ford and Chevy the are increadable. On my Engine Master's Sm Blk Ford the Victor Jr. made 30 more HP at 6,500 but the air gap made 50 more lbs. ft at 4,500. The over -all score with the air gap was better. But if I were running a drag car I would run the Victor Jr. it out ran the air gap above 5,500. So depending on your combo and what you plan on doing with it the air-gap might be fine.
I had always thought Tunnel rams on Bblocks turning under 6500 was a waste, but I was proven wrong by my good friend Danny Crower. The dyno at his Dad's ranch was the proof. I saw a couple of BBlock Chevy's make more trq above 4500 with a tunnel ram and a bunch more HP up stairs above 6000. It all depends on the Cam and Heads.
Sleeper CP

[hotbo]

now this is a good question:confused:
everyone wants to beleive that you need want and love tunnel rams:D wrong.i have seen to many and im one of them take out very good t-ram boats with a single or dual plane intake,single carb.imo t-rams are for looks and looks only in a lake boat.key word lake boat.i just got threw taking out a couple of txs with tunnel rams with 650 plus horse with a rpm air gap and a 750 profrom carb.150 shot of nos on top.torque is a huge factor in jets the more torque the better it will luanch.now i know some will not agree so thats my 2 cents worth hope it helps.do not over carb your boat and yes you can over carb a jet:idea:

[pw_Tony]

now this is a good question:confused:
everyone wants to beleive that you need want and love tunnel rams:D wrong.i have seen to many and im one of them take out very good t-ram boats with a single or dual plane intake,single carb.imo t-rams are for looks and looks only in a lake boat.key word lake boat.i just got threw taking out a couple of txs with tunnel rams with 650 plus horse with a rpm air gap and a 750 profrom carb.150 shot of nos on top.torque is a huge factor in jets the more torque the better it will luanch.now i know some will not agree so thats my 2 cents worth hope it helps.do not over carb your boat and yes you can over carb a jet:idea:
If Sleeper Cp says they made more torque above 4500 then he's probably right, he's around all the Smart Guys Like Dan Crower and Geoff Mummert:D .
When Geoff Dyno'd our small block Dodge it made great power with RPM air-gap. Tunnel Rams can work great, just look at the RPM band on Summit's Kit for their tunnel ram. I never understood why so many people use Performer intakes, when I stomp on my gas it's up to 4000RPM in no time at all, with a slug motor. Good luck

[BlueNun]

I know I should have posted some more info when I asked this question My fault
My engine is a fresh 468 and in the process of being built right now. I want a stout lake boat not a 8000rpm race boat. I have not decided on cam specs or really anything yet. I have a callies crank 4.00 stroke,copmstar h-beams and a set of manley domed pistons with open chamber oval port heads. (Laying around)Compression should be around 11-1 or so if I use this setup I really havent crunched the numbers on the domes etc. I would like to see maybe 6000rpm or so with the A impeller I know my bottom end will hold on to that
My pump is a brand new Ji Berk. with an A impellar

[hotbo]

what you hear and see is what you get oh ya ive been proven wrong on the dyno.but dynos are not boats and they have controled enviroments.you do what you feel is best i did what my head told me.and it always comes true.for a motor that turns 6000 or under waste is what i see.but then again what do i know.im not a expert so im just trying to give my bad advice:D later travis

[Sleeper CP]

now this is a good question:confused:
everyone wants to beleive that you need want and love tunnel rams:D wrong.i have seen to many and im one of them take out very good t-ram boats with a single or dual plane intake,single carb.imo t-rams are for looks and looks only in a lake boat.key word lake boat.i just got threw taking out a couple of txs with tunnel rams with 650 plus horse with a rpm air gap and a 750 profrom carb.150 shot of nos on top.torque is a huge factor in jets the more torque the better it will luanch.now i know some will not agree so thats my 2 cents worth hope it helps.do not over carb your boat and yes you can over carb a jet:idea:
Hotbo,
I'm on the same page with you. I'm not a big fan of Tunnel Rams. Check out the picture of my boat : Single Carb 1050 Dominator, cast alumi intake, through the transom exhaust ,dyno'ed at 855 HP at 6,600 rpm's. Tunnel rams look nice but I'm not impressed. Hell blower look nice, but they don't impress me either, cause I still have a 300HP Nos sytem when the 800+ isn't enough. " Going fast is half the fun...What you make go fast is the other half." But, his question was about trq. If tuned correctly you can do it with a tunnel ram. Your average guy is better off running a single carb on a Victor Jr. or Hi Rpm dual plane. Much easier to tune and run, and alot less $, too. All around ski boat I'll take a Victor Jr. single plane anyday and if I'm turning under 6,500 I'll still take a single plane but that's just my taste.
Sleeper CP

[Sleeper CP]

I know I should have posted some more info when I asked this question My fault
" I would like to see maybe 6000rpm or so with the A impeller I know my bottom end will hold on to that"
My pump is a brand new Ji Berk. with an A impellar
If you want to turn your A to 6000 you are going to need at least 700HP to do it(based off of an old impeller rpm chart I have).
I just don't happen to be a big T-ram fan, but "if" tuned correctly they can run with or out perform a single carb set up. I just don't think most guys that run them tune them on a dyno or check the plugs and change jets once they get them on the water, therefore your other average guy like Hotbo can out run them with his single carb set up. I'm not surprised at all. But you can't beat them for show, but take the time to tune the thing if you're going to put one on your engine. That's all.... otherwise a good single plane set up is just fine and for most engines below 6000 would probably be the best and easiest choice.
Sleeper CP

[Sleeper CP]

How important is torque in a jet?? I see alot of tunnell rams which I know are upper RPM pullers. I am looking at intakes and the Edelbrock AirGap looks descent for a dual plane and it pulls from 1500-5500 I think. Or should I look at the taller single plane manifolds like brodix,merlin, etc??
I'm sorry after all of this , your question didn't get answered. Trq is important, very important , but here is the deal, if your jet can pull 5600 when you are cruising at 4000 it is almost freewheeling, it is not against the wall yet. When you hit it and it runs up against the impeller that is when your trq need is high. So most dual planes that will help you make trq at 3500 how much are they going to help at 5600. In that case a good single plane or rpm air gap will do great. I hope that helps.
Sleeper CP

[LuckyDaze]

Im a fan of my t-ram. But it depends on setup and why you are running it. I have a lot of reversion because of my cam and was having terrible distribution problems with my single carb. I got a T ram for cheap and slapped it on, a little tuning and Im good to go. I under carbed it a bit though and am running dual 450's. It runs great.
~Brian

[hotbo]

im with you cp if a person will take the time and tune properly t-rams work good,but most have them for show.im glad atleast someone has agreed with me for once:) my ole man has a victor jr with a 1050 on his 496 works great.hope this article has helped you some:)

[ck7684]

I went with an RPM Air Gap on my 468, but it's not finished yet, so I cant say how great it is. Seems like the best bet for my needs however...:D

[ap67et10]

I'm sorry after all of this , your question didn't get answered. Trq is important, very important , but here is the deal, if your jet can pull 5600 when you are cruising at 4000 it is almost freewheeling, it is not against the wall yet. When you hit it and it runs up against the impeller that is when your trq need is high. So most dual planes that will help you make trq at 3500 how much are they going to help at 5600. In that case a good single plane or rpm air gap will do great. I hope that helps.
Sleeper CP
this isn't exactly what i have been told...from what i know in a jet you are alway under a significant amount of load at any rpm. This is how i understand it and easiest to explain. in a car at cruise say 65mph you are maybe turning 3000 rpm but your load is only 15-20%, in a jet boat that is not the case. as rpm go up and speed go up your load continues to increase. it does not drop off because you are cruising. from what i have heard at a cruise say 45mph at 3500 or so your load could be up around 60%. this makes sense to me if you just think about what happens when you let off the gas in your boat at 45 mph...the thing immediatly slows down and comes off plane. what happens in a car? you coast. this just show the drag that boats have to overcome not to mention the fact that we do not have gears to releive load. Touque is everything in a jet..that is the key reason why most jets perform the best with big cubes...they make a lot of torque right now. hope this helps.
I'm no expert so i may not have all my info correct if this is the case i would love for someone to explain it better.
ap

[Warp Speed]

Torque is everything, cause that is what is turning the impellar. It is where you want this torque that is important. As I see it (doesn't meen it is right) for most jet boats (especialy high performance lake / race ) you want to mash everything into the 4/4500-6/6500 rpm range (the pump is like having a fairly high rpm converter). You don't want it to be totaly junk below this, but it doesn't take much to spin most impellars 4000. That is where a properly tuned tunnel ram will start to shine. With the right combo, you can really get the power/torque curve to bulge in this area with a good cam / tunnel ram / carb selection. Also, they look cool!!!
With a performance jet boat, I will give up 75 lb/ft @ 3500 to gain it @ 5500 any day!!! (unless you are already struggling down there as it is!) :confused: .
My cent and a halves worth anyway!?!
Warp Speed;)

[e514jet]

Torque not hp is what gets you moving. Lots of good opinions here. I agree with most. If your turning hard enough to take advantage of a tunnel ram
(6000+) then it might be worth your while. The harder your turn them the harder it is on the motor. My combo is simple 514BBF, single plane offy portosonic w/850 and I turn an A/B cut impeller 5400 rpm. gets me to 80 on
gps and i still have yet to put the bottle on. Intake, cam, head combo can't be stressed enough. ;)

[thatguy]

Hot rod boats are hot rod boats. Race boats are race boats.
My wife calls the Miller our "show off" boat. If that's what it is, then show it off.
Yes, TR's are definitly in the show off catagory in MOST boats. That is mostly why I have one, BUT it does also work! Most boaters are not racers. MOST jet boats will not run close to the OPTIMUM RPM potential of any TR. I will give up that little bit of optimum performance for the look factor. It still hauls *as, and looks cool as hell. It may be somewhat of a waste, but thats OK. I know it is not the "right" manifold, but it works for Me. Again, if your gonna show off your ride, then show it off right! ;)
Tommy
PS- My fastest boat has a torker and single 750, V-Drive. My jet has TR and 660's. How backwards is that?:D :D
The jet is way cleaner and pretty, gotta show it off.

[squirt]

all interesting enough but if you look at some dyno sheets and compare them to the RPM's the impeller turns, if you shoot for the lower max TQ rpm number with your impeller you will come up way short! This has been gone over tons and tons and will never be resolved, it is good to talk about tho. Pumps WILL turn above the max tq rpm not just to it. If we keep the disscussion to typical jet boat engines (ie not small blocks even tho they are used and rotary's) then the trend will show if proper planing of components are present the engine will spin the pump up closer to the hp#. If the max tq rpm was the ideal goal then most boats would be better suited with a AA or a AAA impeller,this is certainly not true. Since tq is what is used to calculate hp it is and important#, but in selecting an impeller and chosing a rpm for the engine to run max at I'd look at the hp# and work off that. Thats the way I see things after looking into this a ton!

[Sleeper CP]

Squirt,
I'll agree with that; if he is wants to turn an A impeller 6,000 rpm's he is going to need at least 700 hp to do it at 6000. That's what he needs to build the engine for and not worry about the mid range trq. Everything in the middle I look at it as "flash" in a high speed trq converter.
Sleeper CP

[BlueNun]

Well I am gonna go between a dual plane and a tunnell ram and go for a tall single plane manifold. It will give me more top end and be a good mix I am gonna order the Profiler Sniper Jr. and have it port matched to what ever heads I end up with. This thing should pull hard and I bet I will be the only one locally with this on a jet boat....
http://www.profilerperformance.com/bbc-singleplaneintake-206.html

[Outlaw]

That sniper looks like a team G with a carb spacer on it.
It better be good at that price...$450.00

[steelcomp]

Torque is only a force. Power is what turns the impeller. Anyone want to take a stab at the difference between torque and usable power??
BTW...my little 467 makes 821hp @ 7000 and 680 lbs/ft @5500 with a TR and two 1050's. Makes over 800 at 6500, and makes over 600 lbs/ft from 4700 to past 7000. Any of your motors hold better than 3% power over 2000rpm? Like I said, that's with a TR and 2 1050's, and only 467 small-bore inches. :idea:

[steelcomp]

now this is a good question:confused:
everyone wants to beleive that you need want and love tunnel rams:D wrong.i have seen to many and im one of them take out very good t-ram boats with a single or dual plane intake,single carb.imo t-rams are for looks and looks only in a lake boat.key word lake boat.i just got threw taking out a couple of txs with tunnel rams with 650 plus horse with a rpm air gap and a 750 profrom carb.150 shot of nos on top.torque is a huge factor in jets the more torque the better it will luanch.now i know some will not agree so thats my 2 cents worth hope it helps.do not over carb your boat and yes you can over carb a jet:idea: :notam: :notam:

[squirt]

Torque is only a force. Power is what turns the impeller. Anyone want to take a stab at the difference between torque and usable power??
BTW...my little 467 makes 821hp @ 7000 and 680 lbs/ft @5500 with a TR and two 1050's. Makes over 800 at 6500, and makes over 600 lbs/ft from 4700 to past 7000. Any of your motors hold better than 3% power over 2000rpm? Like I said, that's with a TR and 2 1050's, and only 467 small-bore inches. :idea:
What RPM do you spin your impeller and what size is it? I'm sure it's probably a detailed impeller so going by a standard chart really won't hold much weight, but it sure would be interesting to know. I belive I've seen your dyno sheet on your engine thread but I don't recall if you posted RPM's while running in the boat.

[steelcomp]

What RPM do you spin your impeller and what size is it? I'm sure it's probably a detailed impeller so going by a standard chart really won't hold much weight, but it sure would be interesting to know. I belive I've seen your dyno sheet on your engine thread but I don't recall if you posted RPM's while running in the boat.
MPD detailed stainless BC @ 6400-6500

[steelcomp]

all interesting enough but if you look at some dyno sheets and compare them to the RPM's the impeller turns, if you shoot for the lower max TQ rpm number with your impeller you will come up way short! This has been gone over tons and tons and will never be resolved, it is good to talk about tho. Pumps WILL turn above the max tq rpm not just to it. If we keep the disscussion to typical jet boat engines (ie not small blocks even tho they are used and rotary's) then the trend will show if proper planing of components are present the engine will spin the pump up closer to the hp#. If the max tq rpm was the ideal goal then most boats would be better suited with a AA or a AAA impeller,this is certainly not true. Since tq is what is used to calculate hp it is and important#, but in selecting an impeller and chosing a rpm for the engine to run max at I'd look at the hp# and work off that. Thats the way I see things after looking into this a ton!That's basically the key. Torque alone is completely irrelevant as compared to usable power. Usable power isn't always going to be max hp either. The wider you build your power band, the less you have to worry about a "target" power. This is why big cubic inches work so well, and why small cubes typically don't.

[pw_Tony]

Well I am gonna go between a dual plane and a tunnell ram and go for a tall single plane manifold. It will give me more top end and be a good mix I am gonna order the Profiler Sniper Jr. and have it port matched to what ever heads I end up with. This thing should pull hard and I bet I will be the only one locally with this on a jet boat....
http://www.profilerperformance.com/bbc-singleplaneintake-206.html
Might as well get a fockin tunnel ram with how tall that thing is! Looks badass though...:D

[Jetaholic]

In any application, torque is everything. Horsepower is a byproduct of torque. No torque=no horsepower.
Typically you can figure out horsepower at a given RPM with this equation:
(Torque x RPM)/5252
where 5,252 is a constant value...because no matter what your curve or where your peak HP and torque are being made, HP and torque will always equal each other at 5,252 RPMs.
Let's say your engine makes 400 ft lbs of torque at 4,000 RPM. We want to know how much horsepower the engine is making at 4,000 RPM given that amount of torque:
400 X 4,000 = 1600000
1600000/5,252 = 304.64 HP...basically 305 HP
This engine would make 305HP at 4,000 RPMs.
Torque is basically the measurement of how hard the engine can spin its crankshaft. More torque means better pull/push, which means it will be easier for the engine to get the boat moving from a dead stop. Think of it as the "muscle" of the motor.

[steelcomp]

Horsepower is not a byproduct of torque. Torque does not spin anything. Torque is a work force, or a load being applied. In our case, it's measured in lbs/ft. If you have 100 lbs. sitting on the end of a 12" bar, there is 100 foot-pounds of energy being applied to the end of that bar, but it's not necessarily moving. Horsepower is that same force, being applied over a distance and time. (revolutions per minuter) Forget the numbers, and think of the force as it is being applied. The key word here is power. Too many people get cought up in the numbers and names without understanding what it is.

[Sleeper CP]

Torque is only a force. Power is what turns the impeller. Anyone want to take a stab at the difference between torque and usable power??
BTW...my little 467 makes 821hp @ 7000 and 680 lbs/ft @5500 with a TR and two 1050's. Makes over 800 at 6500, and makes over 600 lbs/ft from 4700 to past 7000. Any of your motors hold better than 3% power over 2000rpm? Like I said, that's with a TR and 2 1050's, and only 467 small-bore inches. :idea:
Well built "little" engine, 1.76HP/cu.in! I can't beat your 3% but I can do 5% over 1,800 rpm's max at 710 lbs. ft at 5,800. Or 98% over 1,600. None the less great built engine, how much compression? My revised version will probably be on the dyno next week with the higher compression the trq #'s will be up so will see.
As my first post stated on the subject: If a TR is tuned and is matched to the heads and cam they can make trq as low as 4,500. But they have to be matched . I think to many people put Tr's on mild 454's that only turn an A/B 5,800. I do admit they looks great, but not being used well.
What do you think, if he wants to turn an A to 6,000 should he build it for max power at 6k or more like 6,250 ?
Sleeper CP