I recently swapped out my Performer RPM, .5" open spacer and stock steel hood for a Vic Jr., 1" open spacer and Glasstek hood. All things equal the glass hood is ~30lbs lighter.

With the old dual plane setup I posted my best ET's ever November 8th at Jackson, Sc. During this time the density altitude was ~600' above sea level. Yesterday I ran my car with the new setup at Montgomery Motorsports Park in Montgomery, Al. This is the first time I've ever raced this track so I have no baseline data for it. As near as I can tell the DA yesterday was ~1,000' BELOW sea level.

Here are my best passes from Jackson (dual plane) and MMP (single plane) respectively:

60' - 1.497
330' - 4.368
660' - 6.789
MPH - 101.36
1/4 - 10.685
MPH - 124.64

60' - 1.503
330' - 4.366
660' - 6.794
MPH - 100.87
1,000 - 8.908
1/4 - 10.707
MPH - 124.82

On these two passes most everything was the same. Carb jetting was 76p/77s with f/r PVs. Timing on the dual plane was 37T and timing on the single plane was 41T. Suspension, tire pressure, staging temps, etc..., were all the same.

They had open time runs yesterday before the bracket race so I got to do some tuning with the new combo. I tried jetting up from 76/77 to 78/79 with little change:

1st pass with jetting changes:

60' - 1.516
330' - 4.381
660' - 6.801
MPH - 101.16

2nd pass with jetting changes:

60' - 1.519
330' - 4.388
660' - 6.815
MPH - 100.85

I then jetted down to 77 square. First pass with leaner jetting:

60' - 1.508
330' - 4.385
550' - 6.820
MPH - 100.54

All 4 passes from above were made launching between 1,200-1,500 RPMs (where I normally leave). I then tried leaving at 2,500 rpms thinking it might respond better with the RPM range moving up 500 rpm with the Vic JR. Results were:

60' - 1.530
330' - 4.420
660' - 6.860
MPH - 100.53

I obviously got some tire spin on that pass, so I went back to my tried and true launch rpm of 1,500rpm or less. I later moved the timing back to 39 degrees with little or no change. I never tried any more than 41 degrees. Horsepower was very consistent as always. Trap speed for all time trial passes were (in order):

100.87, 101.16, 100.85, 100.54, 100.40, 100.53, 100.53, 100.65

ET's for all time trials were:

6.79, 6.80, 6.81, 6.82, 6.83, 6.86, 6.83, 6.80, 6.85, 6.85, 6.89, 6.81

The three next to the last passes were braking during eliminations. I ended up going out in the fourth round. Too bad becuase there were only 6 cars left when I went out.

In summary, as near as I can tell I was running in 1,500' better air yesterday with the single plane yet my ET's were the same or even slightly (.01-.02) slower. Granted I didn't get to tune every ounce out of the new combo but on the surface it appears to be SLOWER.

The decision I'm faced with now is whether to keep the glass hood and intake, or scrap one or both. I really like the hood. It gives me more than 2" of additional clearance and I think once painted it will look primo. I am concerned however that my car seemed to vary by as much as .05 yesterday. Last outing with the dual plane it ran within .01-.02 through the 1/4 vs. the 1/8 (harder to do) ALL DAY LONG. In all fairness, however, I wasn't making changes with the old setup as it was dialed in therefore the variance I saw yesterday was likely due to so many changes (jetting, timing). It is possible that the new hood is creating some turbulance but I sort of doubt it. I think I will proceed with getting the hood painted. I will also leave the Vic. Jr. on for the time being. In the early spring I will take the car back out to some tracks I'm familiar with and do some more tuning with the Vic Jr. If I can't get the ET's to come around I'll be putting the dual plane back on along with a tapared/open spacer combo. Right now I'm running a 1" drop base breather and a 3" element. I could stand a little more breather. I've NEVER tried to run my car without an air filter. Perhaps I should have tried that. Maybe next time.

There you have it...

Thanks for keeping us informed.

Ken, your conclusions sound about right to me. Looks like your a little slower with the vic. I would say you could have run some real LOW 10.60's (and probably high 10.50's)in that air with the rpm set-up. Personally, I'd keep the hood, run a 4" element, and run the rpm. Running w/o the element will require a re-jet and then you'll have alot more turbulence over the top of the carb to deal with. I never saw any improvements running w/o the element with my old 355 so now I just don't do it.

What did you decide about fresh air ducting?

Hey Ken, good post.

I don't know this for sure as I don't own a good weather station yet, but according to a post I saw on DRR, 200' of DA is supposed to be worth .01 in ET.

So, your recent outing had a DA of 1600' less than the previous best, so you should have run .08 quicker in the same dual plane configuration.

Given that, it appears as though the single plane configuration is a tad slower than your dual plane runs.

What I find strange is your MPH did not pick up much at all...would have assumed you would see a good 1 or 2 mph with the dual plane, but maybe sacrificed a bit of 60' and 330'. I'm wondering if your jetting with the single plane needed to be tweaked a bit more?

I'd say to keep tweaking the combination and see what the new configuration will ultimately do. Give it a half a season of runing in all the typical race conditions before deciding whether it worked or not and if the dual plane was indeed better.

I'm guessing that with todays excellent dual planes that the performance difference (fron single to dual or visa versa)on track is minimal from the 330' timers on...60's should be stronger with a dual plane, but every combination will respond differently.

John,

I'm with you. I think the car had a low 60's or high 50's pass in it with the dual plane. As for the cold air box, I've decided to hold off for now. I'll probably get bored over the winter and end up welding something up myself. Might be fun to pass the time.

Todd,

Yes, defintely a tad slower. As for the tuning, as I mentioned I'm sure I could get it to run a little better getting the timing/jetting dialed in like I had done on the RPM, but I don't think the short times would be the same. I knew that the result could end up this way, but in all honesty I expected it to gain ET and MPH. Mike with the 69, etc...) have posted great results using single plane intakes. The reason I thought I would gain is because my converter stalls so high. Everything I'd ever heard indicated that the Vic would outperform the RPM from 4,500-5,000 onward. With my converter stalling at 5k I figured it was a sure thing. Oddly enough I checked my stall yesterday with the Vic Jr and it was ~200 RPMs lower (4,800) than before. Less torque? Maybe Vic Edelbrock should change the name of the intake to the "Outperformer PRM", lol. Many others here with similar combos (FatRat70, Like you said, every combo responds differently. As for tuning during next season, ain't gonna happen. I plan to compete in the Summit points race at Commerce. That means I have to dial my car in before the season starts then leave it alone. I'll get a couple of saturday sessions with the Vic Jr in early spring, but in all likelyhood the RPM will be back on for the next season. Hey, I wonder if I should try an air gap instead... Nah, don't want to spend the money.

I do like the hood. So that's another 30lbs off the front. It was pulling the wheels a little again yesterday, so once I get the low end torque back it might launch real good.

I have found that even with a 5000 convertor a BB likes a dual plane unless the car is very light or the motor very big. I have not tried a Victor Jr but if a 5000 convertor is stalling less you are looseing torque even at that high an rpm.

GateWayRacer are you reading this :D Time for you to get a performer intake!

Ken,

I have Two, 1 I had and 1 from Cable "Bluerebl" coming soon. I am thinking of trying one box stock and then one port and gasket matched to my heads next year.

Good post Ken. Not surpirised it didnt respond to richer jetting. Would it mind a bit more fuel on the initial shot I wonder? Or a bit less plenum volume ( .5" spacer)? I'll stay tuned ,,,

Originally posted by 427L88:
Good post Ken. Not surpirised it didnt respond to richer jetting. Would it mind a bit more fuel on the initial shot I wonder? Or a bit less plenum volume ( .5" spacer)? I'll stay tuned ,,, I forgot to mention earlier. One of my open time run tuning tricks was to go from .035 squirters to .037. No difference :(

You might try a 4-hole spacer on the Vic Jr. When I tested the Team G this summer, a 4-hole spacer made a sigificant improvement.

Numerous times I've been told the air-gap rpm outperforms the non air-gap version, I wish somebody would do some dyno testing to prove this. If the regular rpm runs stronger than your single plane I wonder how the air-gap would work. :confused:

Congrats on the times and on winning a few rounds Ken. Looking forward to running with you next season at Commerce. Sounds like you must be getting more comfortable with the tree. Everytime I think I'm getting good on the tree, I get up there and red-light smile.gif

ken about the air cleaner, mine slows up about 3 hundreds with air cleaner on with paper filter.congrats on winning a few rounds suprised you got to run it wasnt very good weather sat. here.if you have a steel front bupper lose it and gain about a tenth at least .mine didnt seem that heavy but i guese it was where it was at

Originally posted by baddbob71:
Numerous times I've been told the air-gap rpm outperforms the non air-gap version, I wish somebody would do some dyno testing to prove this. If the regular rpm runs stronger than your single plane I wonder how the air-gap would work. :confused: Bob, This is a false rumour going around. The air gap design will allow a cooler intake charge. But all you need to do is run a GM oil splash shield ($12) between the lifter valley and the bottom of the intake with this snap-in-place part There is no measureable difference betwen the two intakes.

Anyone claiming a performance gain between the two did not do a controlled test.

You also have to factor in that some people need to justify their expenditure and claim better results.

Some racers in very hot climates have said that the airgap helped to reduce the chances of vapor lock in the fuel system and fuel boiling in the carb. As I have never personally experienced this phenomenom, I can see where this may be possible especially if they don't have some insulator (phenolic or wood) between the bottom of the carb and the intake.

Bottom line, if you find a deal on a "Regular" RPM, buy it and use it confidently knowing your not giving up anything to the Air-Gap model.

If you like the looks of the air-gap as many do, then definetly get one, they are a great looking manifold and worth the extra bucks many times just for that reason alone.

Ken

I am confused with the launching tech. you used for the single vs dual plane intake. Did you try the 2500 rpm for both intakes or just one and which one? Have you tried the 2500 for both? I think you should be getting alot more out of your suspension. I would work on suspension before the engine changes. Make sure the suspension can handle the engine changes that way the suspension isn't putting any unseen varibles in the equation. The victor may have out performed the dual plane but the suspension didn't allow it to.

todd

Ok, A couple thoughts.

1.) Roll out. Each track is different. Although they are SUPPOSED to be 21", its all in how they measure it.

2.) Traction. Its different compounds/density due to several factors. Ratio of street rubber to slicks. Type of traction compound. Ambient temps affect traction compounds as well. Nothing works below 50 degrees. Although the tires aren't spinning, they CAN slip. The playback recorder on my drag sled will show up to 3% slippage when comparing the GPS and the jackshaft speed sensor. My numbers matched on 330', 660',1000' and top end, so I'm comfortable with the data.

3.) Are you compensating with gears to make up for a higher shift point? You know you lose torgue on a single plane, so you have to run high ratio gears to compensate for running higher shiftpoints. Otherwise, your only using a % of your added power.

Sorry it didn't work out quite right for you. Which jr. did you get? If my memory is correct I believe there are 3 different bbc jr.s I would think the one with the shortest runners would be the best one for your ride.It looks like your still a little rich on the tune up, as you leaned it down it was responding.Maybe even try the smaller one's like the team g and holley strip dominator, hey it's only money tongue.gif As far as the air filter goes, by the x-treme top from K&N it helps immensely when there is not enough room for a big filter, mine runs the same with the 3" and top as it does with no filter.With the solid top and 3" it is .07 slower.

Tom, do you know the part number on the GM splash shield??? thanks

A couple thoughts come to mind real quick... where do you shift your combo at and did you try ditching the spacer? I have found that too many people try to tweak a combo for hp with a BBC, when they don't run the rpm to really worry about it. Especially for a heavy door slammer/street car torque curve is far more important. Secondly the spacer could easily be giving you too much intake volume. It is pretty simple to pull her out for a run and see how she does.Some combos perform with them and some don't.

The lack in mph gain on the upper end is interesting. Definetly keep tunning her and see where she starts making a dent. I'd be real interested to see how you run at the same track between the two.

Very interesting reading though... I will be playing around on the dyno this spring and alternating between my Brodix dual plane and a undecided single plane. So we'll see how my combo fairs.

Originally posted by 66chevelless427:
Ken

I am confused with the launching tech. you used for the single vs dual plane intake. Did you try the 2500 rpm for both intakes or just one and which one? Have you tried the 2500 for both? I think you should be getting alot more out of your suspension. I would work on suspension before the engine changes. Make sure the suspension can handle the engine changes that way the suspension isn't putting any unseen varibles in the equation. The victor may have out performed the dual plane but the suspension didn't allow it to.

todd Todd,

I have tried numerous different launch RPMs with my ride, all the way up to 2,900 which is where the brakes give up and the car starts to push through the lights. With the old setup I found that my 60' times were best leaving just off an idle, say 1,200-1,500 rpms. With the vic jr I thought it might like a little more rpm (since it makes less torque) so I tried anywhere from 1,200 - 2,500, but the results were similar to the dual plane. Now having said that, the temperature Saturday was low 40's and the sky was overcast, therefore the track surface wasn't very hot. Perhaps on a hotter track surface the starting line would have held the higher RPM and the 60' times would have dropped. I wo't know until I try again next spring.

Jeff,

I hear ya on the rollout and variance per track. That's why I stated "This is the first time I've ever raced this track so I have no baseline data for it."As for gearing, I'm running the same 4.11 gear I had with the dual plane. I really don't want to gear the car down any more. I'm trapping about 6,600 rpms at 124-125 now with my 4.11's and 28" tires.

Pat,

I bought the 2902 Vic Jr. As far as I know this is the only rect. port Vic Jr. Edelbrock makes. They make a Vic "R" that has a little higher RPM range and more plenum volume. I do think the tune was a little rich. What's weird is that I have more vacuum with the Vic Jr. (10-11" vs. 5.5"), so I would think it would have liked more jetting. After running all day the tail pipes were darker than they normally are, they are usually a light tan color when the car is running tops. I do feel I'm not getting adequate air to the car. The drop base breather makes the effective volume of the element 2" rather than 3". I seem to recall reading somewhere that 4" was the minimum recommended element size for a 454 turning 6,500 rpm. My next experiment may very well be in that area.

Originally posted by CaptCrunch:
A couple thoughts come to mind real quick... where do you shift your combo at and did you try ditching the spacer? I have found that too many people try to tweak a combo for hp with a BBC, when they don't run the rpm to really worry about it. Especially for a heavy door slammer/street car torque curve is far more important. Secondly the spacer could easily be giving you too much intake volume. It is pretty simple to pull her out for a run and see how she does.Some combos perform with them and some don't.

The lack in mph gain on the upper end is interesting. Definetly keep tunning her and see where she starts making a dent. I'd be real interested to see how you run at the same track between the two.

Very interesting reading though... I will be playing around on the dyno this spring and alternating between my Brodix dual plane and a undecided single plane. So we'll see how my combo fairs. Capt'n,

I shift at 6,500-6,600. No on ditching the spacer. The Vic Jr. intake doesn't have a hole drilled for a vacuum fitting. I needed a vacuum connection for my power brake booster. Rather than drilling an intake that I might or might not be keeping, I opted to drill my $22 1" phenolic spacer instead. Therefore removing the spacer to test wasn't really an option, unless I didn't mind trying to stop the car with no assist from the booster that is smile.gif

Ken.....Did you pick up ET when you shifted at 6500-6600 compared to say 5500-6000.....

Bob,

For Big Blocks GM Part Number as shown. This is about $15. Equalizes the RPM and the RPM Air Gap.

http://www.boomspeed.com/mc71454/splashshield.jpg

Word of warning,
that spalsh shield will not clear Crower SD roller lifters.

He' ken,
I'm learning a lot of this dual/single plain talking!!
Just a small differents in your combo!
I need a vacuum-connection too, VICTOR JR hasn't?

EDDY(riedijk)merlin.

Originally posted by jakeshoe:
Word of warning,
that spalsh shield will not clear Crower SD roller lifters. Jake,

I'm running this same piece with my Crower SD rollers with no problems???