SBC tunnel ram

General engine tech -- Drag Racing to Circle Track

Moderator: Team

555RAT
Member
Member
Posts: 75
Joined: Wed Nov 21, 2007 8:38 pm
Location: Redmond,OR

SBC tunnel ram

Post by 555RAT » Sun Dec 09, 2018 11:35 am

After much research on tunnel rams it soon became obvious that much of the info is related to running a TR on the street. This topic is for a drag race only tunnel ram. My combo is a 414 sbc in a 1750lb dragster, 3.800 stroke by 4.165 bore, 13.9:1, afr 227 non eliminator done by epd a while back, 276/284@.050” on 108lca with a 104.5 icl, 1.6 t/d’s, 1.875” to 2” headers with 3.5” collector, 1.80 glide with 5800 converter and 4:30 gear. For comparison, with a Holley Dorton intake with mild porting and 1.45 X 1.75 carb I’ve run a best of 5.28@129 shifting at 7300 at my local track with a 1.19 60’. This track typically has around 4500’ da. The tunnel ram is an Edelbrock victor ram with 2 of the same 950 carbs I built to mirror each other with 1:1 links. I’m starting with 84 jets, .059 iab, .032mab(I’ll try and get .028), .029ifr, 2 emulsion at .028, .120 N/S, angled floats with the angle at the rear, BG 4 port regulator in front of the ram and planning on 5.5psi. My goal is to determine if the use of a tunnel ram can not only be faster but as, or more, consistent. Does anyone see anything that sticks out as “wrong”?
Keith

Newold1
Guru
Guru
Posts: 1952
Joined: Fri Apr 08, 2016 9:50 am

Re: SBC tunnel ram

Post by Newold1 » Sun Dec 09, 2018 12:32 pm

Be interesting to know what a dyno will say. Know that adyno is not the answer to translating power to the track, but seems like your dragster is probably pretty well dialed in from a chassis standpoint and the only unknown here is how much more power , where, and torque is going to be increased with the use of a more complex intake and carb setup?
If plenum size is holding your engine down a little and it can eat and use the extra fuel then the dyno should show that. If it shows no plus or no change then just look at the old KISS theory in my opinion. There are also some tall, bigger plenum, straighter runner intakes out now and some great single big cfm carbs that work.
The Older I Get, The Dumber I Get :wink:

555RAT
Member
Member
Posts: 75
Joined: Wed Nov 21, 2007 8:38 pm
Location: Redmond,OR

Re: SBC tunnel ram

Post by 555RAT » Sun Dec 09, 2018 12:50 pm

Thank you, unfortunately I won’t have before and after results and the only dyno near me is a chassis dyno but should be able to get me a baseline. The time slip will be my primary indicator of results as that is what will tell me what I’m after.
Keith

User avatar
Dave Koehler
Guru
Guru
Posts: 4257
Joined: Mon Oct 04, 2004 11:19 pm
Location: Urbana, IL USA
Contact:

Re: SBC tunnel ram

Post by Dave Koehler » Sun Dec 09, 2018 3:27 pm

No more fretting, Stick with the TR.
Dave Koehler - Koehler Injection
Fuel Injection - Nitrous Charger - Balancing - Nitrous Master software
http://www.koehlerinjection.com
"Never let a race car know that you are in a hurry."

wheelsup330
New Member
New Member
Posts: 25
Joined: Thu Jun 27, 2013 7:02 pm

Re: SBC tunnel ram

Post by wheelsup330 » Fri Mar 01, 2019 6:03 am

555RAT wrote:
Sun Dec 09, 2018 12:50 pm
Thank you, unfortunately I won’t have before and after results and the only dyno near me is a chassis dyno but should be able to get me a baseline. The time slip will be my primary indicator of results as that is what will tell me what I’m after.
My own on track testing with a 406 combo that was nearly identical cam specs, 14.7-1 compression, ported 227 heads / going from a Victor with an 850 to a Victor Ram with 660's was nearly a full 5 tenths in a door car. 10.10 to 9.60 (1320FT) Ran 9.60-9.62 all day long. (da-averages 200-350)
But Throwing away Gas and Carbs - Putting on a Bug Catcher and running alcohol made it a full second gain. 10.10 to 9.02 and never even need to change pills unless its almost raining. Dead Consistent. Some combos really like the airflow and the methanol.

555RAT
Member
Member
Posts: 75
Joined: Wed Nov 21, 2007 8:38 pm
Location: Redmond,OR

Re: SBC tunnel ram

Post by 555RAT » Fri Mar 01, 2019 9:14 am

Thanks for the info wheels! While I don't expect that kind of improvement it's good to hear that's possible. Hopefully this month we'll get to the track and see what we can do. One thing that is noticeable is the improved throttle response! Can't wait to get to the track.
Keith

User avatar
MadBill
Guru
Guru
Posts: 14122
Joined: Tue Nov 15, 2005 10:41 am
Location: The Great White North

Re: SBC tunnel ram

Post by MadBill » Sun Mar 03, 2019 9:30 pm

wheelsup330 wrote:
Fri Mar 01, 2019 6:03 am
555RAT wrote:
Sun Dec 09, 2018 12:50 pm
Thank you, unfortunately I won’t have before and after results and the only dyno near me is a chassis dyno but should be able to get me a baseline. The time slip will be my primary indicator of results as that is what will tell me what I’m after.
My own on track testing with a 406 combo that was nearly identical cam specs, 14.7-1 compression, ported 227 heads / going from a Victor with an 850 to a Victor Ram with 660's was nearly a full 5 tenths in a door car. 10.10 to 9.60 (1320FT) Ran 9.60-9.62 all day long. (da-averages 200-350)
But Throwing away Gas and Carbs - Putting on a Bug Catcher and running alcohol made it a full second gain. 10.10 to 9.02 and never even need to change pills unless its almost raining. Dead Consistent. Some combos really like the airflow and the methanol.
To me, Rat's 7300 RPM target seems a bit low. What revs were you using with the Victor Ram?
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.

User avatar
af2
Guru
Guru
Posts: 6474
Joined: Sun Jan 28, 2007 4:42 pm
Location: Grass Valley, CA :Northern Foothills

Re: SBC tunnel ram

Post by af2 » Sun Mar 03, 2019 10:11 pm

MadBill wrote:
Sun Mar 03, 2019 9:30 pm
wheelsup330 wrote:
Fri Mar 01, 2019 6:03 am
555RAT wrote:
Sun Dec 09, 2018 12:50 pm
Thank you, unfortunately I won’t have before and after results and the only dyno near me is a chassis dyno but should be able to get me a baseline. The time slip will be my primary indicator of results as that is what will tell me what I’m after.
My own on track testing with a 406 combo that was nearly identical cam specs, 14.7-1 compression, ported 227 heads / going from a Victor with an 850 to a Victor Ram with 660's was nearly a full 5 tenths in a door car. 10.10 to 9.60 (1320FT) Ran 9.60-9.62 all day long. (da-averages 200-350)
But Throwing away Gas and Carbs - Putting on a Bug Catcher and running alcohol made it a full second gain. 10.10 to 9.02 and never even need to change pills unless its almost raining. Dead Consistent. Some combos really like the airflow and the methanol.
To me, Rat's 7300 RPM target seems a bit low. What revs were you using with the Victor Ram?
THAT!!! I don't understand the low rpm?
GURU is only a name.
Adam

wheelsup330
New Member
New Member
Posts: 25
Joined: Thu Jun 27, 2013 7:02 pm

Re: SBC tunnel ram

Post by wheelsup330 » Mon Mar 04, 2019 4:33 am

MadBill wrote:
Sun Mar 03, 2019 9:30 pm
wheelsup330 wrote:
Fri Mar 01, 2019 6:03 am
555RAT wrote:
Sun Dec 09, 2018 12:50 pm
Thank you, unfortunately I won’t have before and after results and the only dyno near me is a chassis dyno but should be able to get me a baseline. The time slip will be my primary indicator of results as that is what will tell me what I’m after.
My own on track testing with a 406 combo that was nearly identical cam specs, 14.7-1 compression, ported 227 heads / going from a Victor with an 850 to a Victor Ram with 660's was nearly a full 5 tenths in a door car. 10.10 to 9.60 (1320FT) Ran 9.60-9.62 all day long. (da-averages 200-350)
But Throwing away Gas and Carbs - Putting on a Bug Catcher and running alcohol made it a full second gain. 10.10 to 9.02 and never even need to change pills unless its almost raining. Dead Consistent. Some combos really like the airflow and the methanol.
To me, Rat's 7300 RPM target seems a bit low. What revs were you using with the Victor Ram?
My Stall (Flash on the T-brake) went up from 5500 with Carbs to 6700 injected, and shift was 8200-8300. Pulled hard to 83-8400
Im guessing also that 7300 would be low, but a Ram designed for the 427-454 would probably fall down close to his range unless it was hogged out.

555RAT
Member
Member
Posts: 75
Joined: Wed Nov 21, 2007 8:38 pm
Location: Redmond,OR

Re: SBC tunnel ram

Post by 555RAT » Tue Mar 05, 2019 10:49 am

That 7300 rpm was not a goal, that was with the strip dominator intake and 950 carb. It didn't make much difference if I shifted at 7600 or 7300 so just stuck with 7300. I'll probably start at 7600 with the victor ram and move up from there to find the sweet spot. Got to wait till all this snow goes away to get to the track though!!!
Keith

555RAT
Member
Member
Posts: 75
Joined: Wed Nov 21, 2007 8:38 pm
Location: Redmond,OR

Re: SBC tunnel ram

Post by 555RAT » Tue Apr 23, 2019 10:36 am

Well I finally got this to the track, not what I was expecting. On Saturday it made nice clean runs from A-B and the 60' were on average a bit more consistent which was nice but the MPH was on average a 3 slower and consistency was no better than with the single four. I gained MPH when I lowered my shift rpm from 7800 to 7400 on Saturday. :shock:. On Sunday I changed the MAB from .031 to .026 and jetted up from 84 to 86 and was a bit more consistent and MPH averaged about 1 better, still slower, and the 60' stayed the same at 1.14 however the ET would jump from 5.18-5.20. Thinking back I should've raised the shift after increasing the jetting. Weather conditions were about 20% more humidity and the DA was roughly 300-500 higher when I ran 5.13-5.15 with 1.14-1.15 60' and 134-135 mph. . This was comparing runs from the same track last September to last weekend. I was a little disappointed at first but by the end of the weekend and runner up by .0008 seconds I can't complain I guess. The lower mph is what's got me baffled, just the opposite of what I expected. The real test will be at my home track this coming weekend!
Keith

555RAT
Member
Member
Posts: 75
Joined: Wed Nov 21, 2007 8:38 pm
Location: Redmond,OR

Re: SBC tunnel ram

Post by 555RAT » Tue Apr 30, 2019 12:46 pm

Back at my home track last weekend and suspecting my valve springs may be an issue I lowered the shift to 7200 and ended up running pretty much the same as last year on. After the first time run on Sunday I found the tunnel ram top just snug to the lower piece and one bolt had fell out. The first time run on Sunday before tightening the bolts was a 5.29@129.9, right on par with my best runs. The next run was a 5.24@131 still shifting at 7200. The next 3 runs were 5.25 and then the last 2 runs were 5.24. It has a bad bog so I'll try larger shooters first but may go up on the MAB a bit also. I'll change the valve springs before the next race and raise the shift rpm back up and see if it maintains that consistency and run a little quicker yet which was the main purpose of trying the tunnel ram.
Keith

Walter R. Malik
Guru
Guru
Posts: 4283
Joined: Tue Jul 24, 2012 11:15 am
Location: Roseville, Michigan (just north of Detroit)
Contact:

Re: SBC tunnel ram

Post by Walter R. Malik » Tue Apr 30, 2019 6:51 pm

If tuned correctly, the dual carb, tunnel ram will be much more consistent over different weather conditions simply because it won't be as sensitive to density changes.
http://www.rmcompetition.com
Specialty engine building at its finest.

randy331
Guru
Guru
Posts: 3242
Joined: Mon Dec 04, 2006 7:30 pm
Location: N.W. MO.

Re: SBC tunnel ram

Post by randy331 » Tue Apr 30, 2019 9:53 pm

555RAT wrote:
Tue Apr 23, 2019 10:36 am
Well I finally got this to the track, not what I was expecting.
What were you expecting ?

Randy

rustbucket79
Guru
Guru
Posts: 1629
Joined: Fri Apr 07, 2006 8:23 pm

Re: SBC tunnel ram

Post by rustbucket79 » Tue Apr 30, 2019 11:37 pm

I compared my 406, super victor 4500 with a 1050 Holley and a victor ram with twin 950 ultra hp Holleys, made the same hp with the nod going towards the single plane having a much fuller power curve compared to the tunnel ram.

Trying these combos at the track I assume would show a trend similar to what the OP experienced.

Post Reply