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Discussion Starter #1 (Edited)
Putting a Tunnel Ram on Peanut Port heads???

I'm currently running and AirGap RPM intake with a 715 Holley with my crappy peanut port heads on my 454...I want a tunnel ram and I have my eye on one with dual 750's. I wanted to eventually snag a pair of 990's but I dont think Im going to take that leap quite yet. What would happen if I put that much cfm on my heads?
 

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Back2K5, please remember that ANY performance enhancements MUST be compatible with the rest of the package, top to bottom. I would strongly recommend building another engine, from top to bottom, with the T/Ram and the 750s in the plan from the beginning.
Enjoy your boat, "as is", until the monster motor is ready... Pull the existing engine and put it under a bench in complete form. Install the "killer" T/ram'd motor, and step on the gas...... IF you have issues with the monster, (and you will), you can always go back to the "old reliable" engine under the bench..... I would highly recommend NOT putting a dual 750 carb'd intake on that engine even IF you had the 990s.... AND, I'm betting the 715 single carb will out perform the T/Ram'd 1500 cfm...unless you're ready to spend some big bucks internally... Speed costs money, how fast do you want to go?......
Ray
 

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Discussion Starter #3
Back2K5, please remember that ANY performance enhancements MUST be compatible with the rest of the package, top to bottom. I would strongly recommend building another engine, from top to bottom, with the T/Ram and the 750s in the plan from the beginning.
Enjoy your boat, "as is", until the monster motor is ready... Pull the existing engine and put it under a bench in complete form. Install the "killer" T/ram'd motor, and step on the gas...... IF you have issues with the monster, (and you will), you can always go back to the "old reliable" engine under the bench..... I would highly recommend NOT putting a dual 750 carb'd intake on that engine even IF you had the 990s.... AND, I'm betting the 715 single carb will out perform the T/Ram'd 1500 cfm...unless you're ready to spend some big bucks internally... Speed costs money, how fast do you want to go?......
Ray
Right now Im into the late 50's early 60's with a full load...Eventually Id like to be in the 70's to mid 80's but speed isn't my main agenda. I love how T-rams look on boats, If I knew I could put this thing on and not gain or lose a single mph then I would...Yes I know Im shallow:)
 

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Back2K5, please remember that ANY performance enhancements MUST be compatible with the rest of the package, top to bottom. I would strongly recommend building another engine, from top to bottom, with the T/Ram and the 750s in the plan from the beginning.
Enjoy your boat, "as is", until the monster motor is ready... Pull the existing engine and put it under a bench in complete form. Install the "killer" T/ram'd motor, and step on the gas...... IF you have issues with the monster, (and you will), you can always go back to the "old reliable" engine under the bench..... I would highly recommend NOT putting a dual 750 carb'd intake on that engine even IF you had the 990s.... AND, I'm betting the 715 single carb will out perform the T/Ram'd 1500 cfm...unless you're ready to spend some big bucks internally... Speed costs money, how fast do you want to go?......
Ray
X2:)hand And " OBNOXIOUS " has a nice short block which would be a great start for you! He has ported 990's also ,and a pretty tunnel ram. Hit him up one stop shopping Close to you.:D BTW the logs look good Now
 

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Discussion Starter #5
X2:)hand And " OBNOXIOUS " has a nice short block which would be a great start for you! He has ported 990's also ,and a pretty tunnel ram. Hit him up one stop shopping Close to you.:D BTW the logs look good Now
Did you get them all hooked up? Any pics?
 

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tunnel ram add on

Did you get them all hooked up? Any pics?
Another route you could look at,if you really want the tunnel ram on the boat, is to pull the heads and gasket match the peanut ports to large port. And I would try to find a top plate and run one of the 750 but both is a bit too much. Just my (cheap fix) opinion.
 

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I'm currently running and AirGap RPM intake with a 715 Holley with my crappy peanut port heads on my 454...I want a tunnel ram and I have my eye on one with dual 750's. I wanted to eventually snag a pair of 990's but I dont think Im going to take that leap quite yet. What would happen if I put that much cfm on my heads?
One time a friend of mine thought he would gain performance by ditching the "stock" 715 cfm Holley carb off his very mildly build 454 (stock 4.250" bore and pistons, oval heads, zero decked, mild jet boat cam)that I put together for his boat. He bought an 850 Demon without checking with me, 20 foot open bow jet boat with mild pump work, turned around 4900-5000 RPM before and after the carb change, even with lots of time spent trying different jetting.

You can put a tunnel ram on your engine, but I think you will lose some low end performance.
 

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X2 on Moneypit's advice. Your system as it is, is good to about 5,500 Rpm. Depending on your pump impellor you may not be turning that high now. Throttle response and engine performance is a function of flow velocity through the carburetor, intake, and exhaust system. What the other members are suggesting is by doubling your carburetor CFM and going to the tunnel ram with no other changes, the flow velocity is reduced significantly. Means poor throttle response, possibly increased fuel consumption, and loss of engine engine performance until about 4,000 Rpm or so. If it is the look you are after and are willing to suffer the probable reduced performance, the tunnel ram will look good. You just may not be happy with the way your boat runs after making the changes.
 

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Really?

Please explain this! :D
Basic STOCK 454, "with crappy peanut port heads".... Not to mention the extremely MILD camshaft, flat top pistons, and a STOCK bottom end..... Why would anyone want to destroy the drive-ability of a pleasure boat strictly because a T/Ram "looks" meaner? There is a very good reason why it came with the 715, it's called "do the math"......
Ray
 

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Basic STOCK 454, "with crappy peanut port heads".... Not to mention the extremely MILD camshaft, flat top pistons, and a STOCK bottom end..... Why would anyone want to destroy the drive-ability of a pleasure boat strictly because a T/Ram "looks" meaner? There is a very good reason why it came with the 715, it's called "do the math"......
Ray
Well here is what worked for me

100k Mile Stock Suburban Motor
Ok Solid Tappet Cam Nothing Huge
Tunnel Ram w/2 yes 2 750 Carbs
Pretty Much that about it

Went 84mph in a Bahner Jet w/Stock Pump NO Ride Plate, Shoe, Stuffer or non of that fancy stuff there!
Same Combo in a Poorly Rigged 72 Hondo Flatty went 90.0
Same Combo in a Hondo TR-2 went 94.7

OH YEAH PUMP GAS!!!!

And Drivability was awesome!!!
 

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Basic STOCK 454, "with crappy peanut port heads".... Not to mention the extremely MILD camshaft, flat top pistons, and a STOCK bottom end..... Why would anyone want to destroy the drive-ability of a pleasure boat strictly because a T/Ram "looks" meaner? There is a very good reason why it came with the 715, it's called "do the math"......
Ray
Ray...your math is wrong!
Doesnt' matter if the 454 is a stock bottom end or one that is built to the hilt because the cubes are just along for the ride (especially at only 6,500rpm) 95% of the power in any combo is made from the Camshaft, heads and intake system. And Chevrolet put 990's on stock motors. Like Haulinass said, they work great on 8.5:1 compression Suburban shortblocks and 13-1 race motors. Been there, done that. NOthing better than running nearly 95mph with a $1,500 motor season after season on 87 octane (and still running to this day I might ad)

To the original poster: Put the ram on it. You probably wont gain a thing being that you have the small cam and heads but for now it will look cool. Later you can upgrade the heads and camshaft and have some real fun.
 

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L.A. City Schools

Ray...your math is wrong!
Doesn't' matter if the 454 is a stock bottom end or one that is built to the hilt because the cubes are just along for the ride
OK I went to LA City Schools, maybe it's old math, but math doesn't really change. An internal combustion engine is nothing more than an "air pump". An air pump that will only pass "so much" air through it at a given RPM... (Unless it has some sort of "boost")

Simple formula: CID x max RPM
---------------- OR
3456

454x6000
--------- = 788
3456



So, please point out where the equation needs correction? I realize the OP most likely won't see 6000, but it is a nice round number.... (5600= 735)
There is no correction for intake/exhaust, or cylinder head differences because it is based purely on CID. While different heads flow better than others, or different cams/exhaust systems can add/deduct from the basics, it is the actual CID that is the limiting factor when it comes to flowing air through an engine under NA air pressures. OK, Ok, a slight "fudge" from these numbers is apparent in certain applications, but to attempt to DOUBLE the cfm is ludicrous, and will not be anywhere close to the 100% volumetric efficiency standard used above....
Math does not lie...
Ray
 

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OK I went to LA City Schools, maybe it's old math, but math doesn't really change. An internal combustion engine is nothing more than an "air pump". An air pump that will only pass "so much" air through it at a given RPM... (Unless it has some sort of "boost")

Simple formula: CID x max RPM
---------------- OR
3456

454x6000
--------- = 788
3456



So, please point out where the equation needs correction? I realize the OP most likely won't see 6000, but it is a nice round number.... (5600= 735)
There is no correction for intake/exhaust, or cylinder head differences because it is based purely on CID. While different heads flow better than others, or different cams/exhaust systems can add/deduct from the basics, it is the actual CID that is the limiting factor when it comes to flowing air through an engine under NA air pressures. OK, Ok, a slight "fudge" from these numbers is apparent in certain applications, but to attempt to DOUBLE the cfm is ludicrous, and will not be anywhere close to the 100% volumetric efficiency standard used above....
Math does not lie...
Ray
All you did was prove that you can read the back of a Holley box.
Don't base anything on Cubic Inches or use a standard platform for determining intake systems FOR ALL engines with similar sizes. As noted in my previous post, Peanut heads are not ideal for T-ram systems however 990's love them. You stated differently by going off of cubic inches alone. Cubes have NOTHING to do with it while Heads and Camshaft do.
Where your "Basic Rule of Thumb" fails is that it doesnt take into account the most important aspects of making power, Heads, Camshaft, compression etc.
 

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Well then i guess an almost stock 455 that revs no more than 5k would be 'slightly' over-carbed with 2 660's that open all barrels at almost the same time...probably idle poorly, have crummy part throttle response and get terrible mileage.....
I just knew it would when i bought it...I didn't care, i wanted the look
so i bought it.......
And i was right, it ran so bad first try, i drove past the no-wake buoy, turned around and put it back on the trailer.
Took it home....ditched the 40# flywheel for a flexplate, did some sandpaper work on the acc. pump cams, drilled the squirters with the next size up in my tip cleaning set for my torch and locked the dizzy out and set it full advance......
It really surprised me how much better it ran...no bogs/backfires/stumbles or flat spots anywhere. It would idle in gear all day long @650 and if i got caught in traffic in the channel and had to shut it off it would re-light and idle so clean i couldn't even hear the starter. Just a tap on the gas and it would plane @1600 and would rev just as fast as i could move the throttle....

WOT with to much gear and to big of a prop it would just spin 5100, back off the throttle 1/16" was 5k...and usually got 3.5 per gal. And
ran with a stock olds car fuel pump.

I probably just got lucky with the tune...first boat i ever worked on, haven't touched a BBO or a holley in 30 years. And i must admitt that i never tried it with a single 4bl. but i can't see how it could run
any better.

Ditching the flywheel was probably the most important thing, i could see it needing 50cc pumps to cover that amount of weight. The intake runners are about 20% smaller than my weiand for BBC that are on the small side compared to stuff i see at work....

If i were you i would take a run at it....you have some info concerning things you can change to get it to run better....and ya, 750 might be a little big, but they are only big when they are open all the way....... :)bulb
And yes Ray, i know what the math says and i bet my deal would run plenty poorly in a street car...that 1500-2500rpm zone where a street car spends most of it life, is a problem, but boats don't spend much time dogging around in traffic.....:D.:)devil
 

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4bbl carbs are rated at 1.5"hg. Most performance motors are going to spec a carb or tb that will be larger than this and present less restriction than 1.5"hg.

Another thing, say you use a better for performance sized carb and it shows .8"HG.

So, since carbs are rated at 1.5" the bigger carb flows less than it's rated cfm at .8"HG.

SUmmary:
Carbs will flow more than their rated cfm if they cause more restriction than 1.5"HG
Carbs will flow less than their rated cfm if they provide less restriction than 1.5"HG
* Assuming rated cfm is stated honestly.

Don't forget that intake manifold has a huge determination on what size carb to use.
A dual plane can take much more carb than a single plane. on an otherwise identical motor. Dual plane only let's each cylinder see air from two throttle bores vs all four.
A tunnel ram (although plenums are connected) places each throttle bore a short distance from each intake runner. This causes more , but not total, use of 1 throttle bore per cylinder. The closer the carb to the runners (shorter plenum) the larger the throttle bores/carb you'll need. Independent runner intakes (IR) has one throttle bore per cylinder. There is no common plenum(s). These need much, much larger throttle bores and thus way higher cfm rated throttle body / carb then anything else.
 

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Bad advice....?

OK guys, as I read the OP's post, it seemed as though he was asking about a rec port T/ram w/ a pair of 750DP carbs, onto P nut port heads on a basically stock 454. I assumed it was a rec port t ram because he intends to "one day" budget a set of 990 heads for his boat and use this same t ram.... If he runs the rec ported 1500 cfm capable induction on the existing set up he will puddle liquid gas at the intake to head transition, as well as behind every intake valve. While it is agreed his performance will drop off until the 990s come about, the idea of fuel polluted oil, and the resulting bearing damage has been ignored... My first response was a suggestion he start building another engine that is engineered for the t ram and the 990s from the beginning, which, IMO, was sound advice to a fellow boater. Also, IMO, if he puts the t ram and carbs on his existing engine his fun and games will be short lived, which is why I suggested he not mess with the working combination he has now... I have seen dozens of good running boats "fixed" only to have them parked after one or two water trips. IMO, advising him to install the t/ram for the "look" while ignoring the consequences is bad advise.... Granted the math used for computing cfm has a few variables, but to more than double the computed cfm is bad advise. He won't be having fun, and he won't be happy with the results...
Ray
 

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Discussion Starter #19
I decided to not go with the T Ram. Too much money for too much unknown. Im going to take MoneyPits advise and run with the "If it aint broke, Dont fix it". The 454 runs fine as it is and I have plenty of work to do to get it ready for the Lake in the next two weeks without adding stuff I dont know about, like motors:), into the mix. I'll build a nice engine when I actually have money one of these off seasons because I still have to move from the three point mounts to 4 point and do some pump work as well. I appreciate everyones advise. Who ever said boating was cheap??? Oh yeah...nobody.
 

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I decided to not go with the T Ram. Too much money for too much unknown. Im going to take MoneyPits advise and run with the "If it aint broke, Dont fix it". The 454 runs fine as it is and I have plenty of work to do to get it ready for the Lake in the next two weeks without adding stuff I dont know about, like motors:), into the mix. I'll build a nice engine when I actually have money one of these off seasons because I still have to move from the three point mounts to 4 point and do some pump work as well. I appreciate everyones advise. Who ever said boating was cheap??? Oh yeah...nobody.
:)devil
 
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