The Jalopy Journal
Discussion in 'The Hokey Ass Message Board' started by Smoothy, Dec 8, 2018.
Camshaft selection is enormously important in maintaining intake velocity. Remember, in a non-digitally-controlled engine, the cam is the "program" of the system.
Get that wrong, and your fuel will only be properly metered at high RPM's, if at all.
Lazy air flow or busy air flow?
Laminar flow, turbulent flow, the transition between the two, in relationship to the boundary layer.
Science blinded Thomas Dolby
No, the science of woman is different. They suck us in most efficiently. Put that apple and the end of a vacuum.
No, a woman blinded Thomas Dolby, using science.
Don't think anyone mentioned the Holley 660 center squirters. Best carbs for a tunnel ram, I'm told.
There's chemistry involved in the women/blinded situation, fo' sho'.
Violence, too. She did hit him with technology.
For the strip only....
I have often through about getting a tunnel ram, slipping high temperature plastic tubing into the runners, and filling the space in-between the tube and runner wall with high temperature epoxy. Or even create a dual-plane tunnel ram.
By decreasing the runner diameter, the velocity would be increased, resulting in better fuel metering, at lower RPM's.
^^^^^ Tune port
I have seen replacement tunnel ram tops that simply break the top plenum in two, so each carburetor serves only 4-cylinders.
The trouble with that scenario is firing order.
Let's look at the venerable SBC, with its 1-8-4-3-6-5-7-2 firing order.
1: Carburetor 1
8: Carburetor 2
4: Carburetor 1
3: Carburetor 1
6: Carburetor 2
5: Carburetor 2
7: Carburetor 2
2: Carburetor 1
This stacks the firings, and thus one instance three intake strokes on Carburetor 2, where Carburetor 1 has no more than two-in-a-row.
This absolutely will decrease efficiency in fuel delivery.
What effect that this has in the real world, I cannot say, but could make for a funky torque curve.
In the past I've posted several articles and dyno tests with multiple brand engines showing and proving that tunnel rams increase torque over single fours and also showing that the hp difference is negligible.
I ran a tunnel ram just as you intend to do, albeit with closer to 50/50 racing to street duty, and never had issues.
My setup was 383 sbc, 538 lift, 10.5 compression, aluminum heads, TR1X with 450's, full MSD ignition, 3500 stall, th350, 4.11 and 4.57 gears, 2600 lbs with me.
I live in the city so plenty of stop light to stop light driving, worked 45 minutes away which was out of the city so 60 mph driving in stretches. The car pulled the wheels every pass foot braking at the track on 93 octane pump gas.
The new pump gas 489 will also get a tunnel ram on it, if you were closer I'd let you borrow a spare tunnel ram I have to see if you like it or not.
In the Mopar small block world, there is a Hot Rod Magazine article which supports your experience. Steve Dulcich made over 600hp out of a little 340 using iron W2 heads and a tunnel ram. The science here is what others had suggested: keep that air moving!
For big blocks, Mopar has the best of both worlds: a cross-ram six pack! The runner lengths are similar to a tunnel ram but they are sort of laid over so the whole thing can (almost, sort of) fit under a factory hood. DirectConnection made special Holley six pack carbs without the vacuum cans on them. And, as others have said....you gotta play with the underside of the plenum to keep liquid fuel from running into the ports. Mopar used to suggest racers epoxy "popsicle sticks" or build up epoxy walls to herd the fuel puddles away from the runners.
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Alot of the crap talked about Tunnels is due to improper combination of motor and heads and cam. TR on big blocks can be made to perform well, and very street-able... I will say it will be hard to beat your current setup with a TR and 2 cheapo 450 cfm carbs.. If you put some quickfuel 450s on there it will be alot more tune-able. Honestly I think that torker 2 with a 850 quickfuel would bring you up alot also. But Since your rear is weak, Id say don't throw money at motor till you got a tank under the rear.
TR are cool, mostly for looks, big blocks pull them off better than small blocks due to the displacement, the weiand TR are a good piece. Under the carbs put a 1/4" tall, 4 hole poly spacer to get a little better transition, and better throttle response. Either combo you run, TR or Torker 2 you will be there close to where you want to be with heads most likely and a decent bump stick. about 230 @.050 duration and 510-530 lift will put you there. If you used stock oval port heads, with a decent cam you can get by even cheaper.
MoPar slant 6 was a horizontal ram and ran just fine . But I am old and sometimes I don't know what I am talking about . LOL
Dyno run; dual plane vs. tunnel ram on a 400 Chevy.
Looks like you need to subscribe to get that, can you do a screen shot of torque/HP curves?
Weird, that's an old episode and should be free to watch (I'm not logged in, and can watch it). Try googling "engine masters" and "tunnel ram" and follow that link.
Anywho, here are the curves:
Dual plane vs. tunnel ram
It's a Blueprint Engines crate engine, and they talk about all the engine specs before the dyno run.
look for it on youtube, not mtod
Your input has really influenced me greatly. After sitting down and thinking about it the tunnel ran is the way I want to go. Plus, now someone with real world experience with an engine similar to mine has said it works. That's enough convincing for me.
However I think I'll still plan on really dialing the car in with the Torker II and single carb. I'll do it just to make it easier on myself, and not face so many possibilities at once. Luckily enough I'll have a good to hide it hahaha.
By the way, your coupe is awesome.
Moriarty, this is "kind of" the plan. I built the big block before I ever did find out the car was in a few magazines. So, it was hard to convince myself to revert back to a 350 after having already spent the money. The idea behind my take on the car is to revert it back to the way it appeared in the magazines, but with the big block. The tunnel ram shouldn't have much of a visual effect until the hood is open, as the car was fitted with a hoodscoop.
I have had tunnel rams on the street and worked well with allot of carb tweaking.
Was the car faster or quicker? Not really.
Stop and consider this for some time, there are numerous NHRA and IHRA Stock Eliminator cars with Big Blocks that run in the 9-11 second 1/4 mile and this is done with stock configured engines with stock lift cams. I have had 1st hand experience in this.
My point is with factory intake manifolds and a factory tweaked carb, the proper camshaft ( I highly recommend Bullet Cams) along with making the car launch hard, you will be where you want to be.
If the car doesn't leave hard and 60' well, your going to be disappointed.
People have been making street/strip cars work for years, the operative word is "work", the 80% street driving time could be a stumbling, slobbering and all around cantankerous disappointment, it will require all components be carefully selected and skillfully tuned to be enjoyed.
Thank you Captain Obvious ..
Thanks for the kind words.... it's far from awesome but it would be hard to have more fun in a heap like that!!! Build it, beat on it, then make it better! Good luck and please share your experiences. Real world stuff is what we all learn from!!!!
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