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Discussion Starter · #1 ·
Hi guys.

I have a ongoing enginebuild, and wondered if someone could tell me the advantages/disanvantages of a sheet-metal tunnelram.
Is the powergain worth the money, and what will a typical gain be over a single plane intake.

Living in Norway, a tunnel ram will cost me alot more than in the U.S due to taxes and freight costs.

Engine is a 4.60"x4.375" bbc.
-Heavily ported ProTopline 360cc.
-Venolia gas ported pistons. Aprox 14:1 compression.
-Bullet solid roller cam (builder wont give me the spec's, but they say it's fairly aggressive).
-Jesel Beltdrive & valvetrain.
-Moroso external wet sump oilsystem and Moroso vacuum pump.

This will be a dragrace engine only, and will not see the streets at all.

Living in Norway, a tunnel ram will cost me alot more than in the U.S due to taxes and freight costs.

Cheers. And sorry if my English aint top stuff :D
 

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A tunnel ram will make more power on your combination if it is properly built. They are not all created equal. If the cost is that much higher for you, you may want to stick with a single 4. The best type of tunnel ram is a sheetmetal design, but it needs to be properly built for your application. It is not just the intake, but the linkage, carburetors, shear plates, etc..it all adds up. and you may need a looser converter, gearing, etc.. It is expensive in the U.S. so I can imagine how much more it would be for you, and may not be worth the money. Keep in mind, they may make more power, but the e/t difference may not be there if the car isn't set up right with converter, weight, gearing, etc...I have seen mph increase alot, but in some cases in the wrong car or if it is not setup for it, only see a tenth or two in worst cases. I would probably spend the money elsewhere.
As for not knowing what camshaft you have, that is kinda silly when you are the one who paid for it, no? Especially since whoever builds the intake if you decided to go with it will need that info.
 

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Discussion Starter · #3 ·
Hi, and thanx for the respond. :)
If a tunnel ram is to be bought, the shop guys will do it for me. They have some deals with CFE i think.
As i understand, my cam is a customgrind without serialnumber and everything. The reason i think, is that the racing community here is quite small, everybody knows everybody, and with an increasing amount of people building engines, I do understand that some will keep their combos to themselves.
My goal is to run in a heads up class with a 7.60 index, but i am concerned that my little engine wont do the job if i dont get as much power as i can. It will be on the bottle tho.
Most guys running the same class, have bigger engines or big chiefed stuff.

Thanx again :)
 

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If on the bottle, I wouldn't spend the money on a sheet metal intake. Cast 4 intakes can make a lot of power if they are ported correctly then you add nitrous and you should be able to make the power you need.
 

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^^^^^^^^^^^ The Mystery cam is getting more popular all the time. It is stupid like you can't send it out and find out or degree it yourself and plot it, but "Sonny More Money" has done this for years
 

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It's one thing if the CUSTOMER knows and doesn't want to say... it's another thing if you have a serial number in your hands and nobody will give you the specs if YOU own it. Otherwise that's why we have Cam Doctors!
 

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Discussion Starter · #8 ·
From the builders point of view, i can understand this. Why spread your skills and knowledge in the hands of your customers and trust they "wont tell"?
I really dont mind this. I trust and have a great relationship with my enginebuilders. As they are in racing themselves, being at the track, they become something more than just business partners, you know? :)
Anyhow.. Any to recomend a cast single intake? Super Victor?

Thanks for the input. Great forum :D
 

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I would agree with everyone on the cam issue thats just dumb its your cam you should know if not put it on a cam doctor. As far as the sheetmetal manifold goes this depends alot on you how much you want to spend to pick up!! If you dont mind spending the $$$ then yes I would do it as long as its for your applacation and not one bought off of racing junk for a big block chevy convantional head, You should see a good gain but dont expect a huge gain over a well done cast manifold but their is some there and I agree all your other stuff needs to correspond with each other to get the full value of it or its a waist JMO.
 

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Had a 598 bbc once with heads and super victor intake both ported by EAGLE RACING ENGINES. Installed a sheetmetal intake that a friend of mine had laying around then had two dominators done for the motor by AED 1230 cfms. Car picked up O et at the track. The problem was probably what these guys are saying the intake was not built or the combination.
 

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A properly built intake will make more power. Period. Like I said though, if the car is not set up for it, you may not see a change first time out and blame it on the intake setup, which I see guys do over and over, and that is not just with intake setups. The fastest point from A to B is in a straight line. If the intake is built correctly, airspeed and airflow will go UP through the intake, as we all know, it goes DOWN with a 4 barrel intake due to the turns, as air dowsn't like to turn. Tunnelrams often require more rpm as well, which means the converter, gearing, shiftpoints all need to be altered and if not, you may not see a difference in e/t. A healthy 582 inc combination should love a custom sheetmetal intake, built right, with proper carburetors an in my preoffesiional opinion, is worth it. But don't expect miracles as you may need to adjust other parameters of the combination. If you stick with a single carb deal, go with the Profiler intake and good dominator. I am a big fan of a properly built T-Ram setup, but the single four is often more consistent and easier to tune. If you are looking for every bit of power, I would look into doing the twin dominator setup. And if it makes more power n/a and runs faster, it will do so on the hit as well.

As for the camshaft deal. Every builder can tend to be sneaky so to speak, I am guilty of it as well sometimes, but only if the combination is making so much power due to the grind, over and above what most are getting from the combination. Otherwise It doesn't matter. BUT, not telling the customer who actually paid for it is a little silly. That is done just to keep them from going and asking for help from anyone other than the guy who built it..All it takes is to degree it to know what it is.
 

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I get these type of phone calls regularly, and I'll give you the same answer I give to those who call me:

Tunnel rams work best on raised port heads. OEM type V-8 port locations (i.e. port floor very close to deck) almost always have too low of a trajectory to utilize the correct runner length before the right bank intersects the left bank leaving no room for the plenum. When you tilt or "bow" the runners upward to prevent this, performance will suffer. I've experimented with tilting runners up (and down) in 1 degree increments and seen 30hp losses with only 1 degree of change from the optimum trajectory. Your only other option is a shortened runner, which will also hurt performance unless it is a very high-winder. Either way, there will probably be some serious compromises. This is the reason raised port heads make the power they do with a good tunnel ram. Blanket statements like "a sheetmetal manifold is worth 50HP" can really disappoint you on a conventional head application. Keep your money, and start saving for a set of raised port heads. Then a well-designed tunnel ram will really shine.

www.swartzracingmanifolds.com
 

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I don't think the statements would be blankets if the dyno shows they make more as does the e/t slip when it goes faster down the track. I do agree, the raised runner type heads will benefit more, but a properly built intake will and has, made more power on a given combination. Might seem like a waste of money to some, but when you are looking for every bit of power, you spend the money.
 

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it depends on the level of power and how good the fuel distribution is.

a LOT of times a custom made intake is altered internally just to correct flow areas that a cast manifold cannot achieve.

there are JUNK performance level sheet metal intakes. many are able to flow the air and fuel,...but just do not mix or carbureate very well to ALL of the cylinders.
the visual of what is INSIDE the flloor and plenum area is the KEY.

sometimes it is best to BUY what someone else has allready tested and accomplished, and then if you see fit, then you alter.
 

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You are correct. That is the difference from a basic sheet intake and one custom built for the application, taking into consideration, std heads, rpm, camshaft, operating range, carb sizes, compression, etc etc just to name a few things. It is just one of those "design" over flow things again..It is a known fact air doesn't like to turn and the fastest way from A to B is in fact a straight line. Now once you have that straightline, the right intake will get the air through it in a hurry, and the wrong one won't. But it is like anything else, nothing is 100% guarenteed and may need to be altered from the base design, but as long as you know what you are looking at and can work with the builder, you will find the sweetspot. Same holds true for Converters..never 100% out the gate. I am just a big fan of a well built tunnelram.
 

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Discussion Starter · #17 ·
Thanks for great answers. WOW never knew that it was so important to have just THE right intake for an engine. Thought it was the straight runners, and increasement of the space before the intake runner in the head that did the trick.. Guess i really need to think this over. The profiler cast 4 intake aint cheap as well. Thanks
 

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...It is a known fact air doesn't like to turn and the fastest way from A to B is in fact a straight line....

My point exactly. But on a low port, you can't fit a straight runner of the correct length into the package. The exceptions would be:

1 - an engine with excessive deck height (not exactly the trend)
2 - an engine that operates at 9000+RPM (short runners)
3 - a cross ram runner arrangement (not easily fabricated, among other problems.)

Air doesn't like corners, but more importantly, fuel HATES corners. When you tilt or bow the runners upward, it "throws" the fuel out of suspension and crashing into the port floor. All the plenum "tricks" in the world won't fix that. And then the problem is compounded by the fact that the runners are pointed back up at the carbs, which causes reversion problems. When you look at a good performing tunnel ram, look at where the runners point when the charge bounces back into the plenum. The runners will point back at the opposite corner of the plenum, not at the carb base. On the other hand, this is why fuel injected applications (with port or down nozzles) can get away with the "banana" runner (i.e. sprint cars).

Single plane manifolds have curves, but they curve front-to-back, not up-and-down. This doesn't seem to hurt as much as throwing it into the floor. In fact, most sheetmetal manifolds have some tilt front-to-back to accommodate the stagger from bank-to-bank and to position the runner openings under the carbs.

For the most part, manifold design is a "packaging challenge"...simply squeezing what you need into the space you have. A low-port carbureted combo is the worst possible scenario. Consequently, the hunt for a gain can be elusive (but not impossible). This guy is concerned about the cost of taking ONE wack at it. I do this every day, and I can't tell him for sure that I could do it on the first shot. Can you?

www.swartzracingmanifolds.com
 
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