tunnel ram results

[prairiehotrodder]

For anyone thats been following my progress with my pump gas 540 BBC in an 81 malibu, I have some results to report. The car is 3400 pounds with 4.10 gears and a glide with an ATI 5200 convertor.
The motor is 10.0 CR with AFR 335 CNC heads.
Last season I bought an old used Lunati cam to replace my Straub cam (should have kept it) and ran a best of 9.94 at 135 mph in decent air with 10.0 at 134 being much more normal.
The Lunati cam was 274/283 110 LSA #50214 and i was using an edelbrock super victor with a QFT 1050 dominator.

In my quest to be more solidly in the 9's and just go faster i decided to try a tunnel ram and a different cam (I know, don't do 2 things at once)
The cam is an Erson 274 / 278 with .740 / .740 108 LSA
The tunnel ram is the weiand with a pair of 750 holley track warriors.
It took me some time but i think i have an idea now of what these carbs want. Here is the results :
Today I went 9.84 at 135 in the morning and 9.90, 9.91. 9.93 all day in the heat. I am happy that the car stays in the 9's now. I basically gained .1 of a second and 0 mph. Maybe there is more to be gained and maybe some of you have some suggestions for me (Feel free to let them fly). I think what happened is i gained some torque in the midrange but no horsepower on the top end. Does that sound reasonable ? And i don't know if thats more because of the t-ram or the cam swap.
brian

[GARY C]

At that CI I would want to try bigger carbs and maybe even more gear and or converter to favor all the big parts.

[F-BIRD'88]

Keep workin on it. You're doing great. Rome was not buolt in a day.. Wondrr why no gain in mph...,

[F-BIRD'88]

Could be carbs need more tuning... or car needs some low cost areo/ mph tricks. or both. Right from the late great Joe Sherman's play book. He was a master on this.

[prairiehotrodder]

At that CI I would want to try bigger carbs and maybe even more gear and or converter to favor all the big parts.

John at AED specifically told me that a pair of 850's would be to big for this motor. Other carb guys suggested a pair of 1050 dominators. Hard to know what to do and to exspensive to experiment with parts like that. I think the car would like a little more gear, maybe 4.30's.
I'd like to find some mph or know why.
Brian

[GARY C]

At that CI I would want to try bigger carbs and maybe even more gear and or converter to favor all the big parts.

John at AED specifically told me that a pair of 850's would be to big for this motor. Other carb guys suggested a pair of 1050 dominators. Hard to know what to do and to exspensive to experiment with parts like that. I think the car would like a little more gear, maybe 4.30's.
I'd like to find some mph or know why.
Brian

I just seems you have a borderline 8000 rpm engine with 6500 rpm worth of compression and carb. It's hard to know what will work best on a mismatched combo.

[Casper393W]

Congrats! What was the weather conditions for this time vs last time out? I too believe with your CI larger carbs would definitely make more power!

[steve cowan]

Brian,
my calculations you are around 640-650 hp
what rpm do you shift at and also across the stripe
great bracket car to say the least,we can all say it needs more compression ,bigger carbs,the tunnel ram is better for high rpm etc etc etc,but sometimes we have to do the best with what we have on hand at the time.
PS - you need a 3 speed auto cause car bit heavy LOL, could not resist sorry !!!!!

[vortecpro]

"Find some MPH"

You need to work on the car not the engine. 1320/135 = 9.77 and that's just a starting point, you can do better. Steve's right.

[Frankshaft]

What's the 60? Do you street drive it at all? Trap rpm? More converter and gear would definitely help, but it's running good. But like Mark pointed out, its at least a .10 off from the mph.

[Steve.k]

I went to dual dommies and tunnel ram on my 438. We dynoed engine afterwards and engine picked up 54 peak hp at exactly same rpm 6700. The real nice thing is the 35ftlb tq it added through the low end. No other changes once so ever to engine.

[Frankshaft]

I went to dual dommies and tunnel ram on my 438. We dynoed engine afterwards and engine picked up 54 peak hp at exactly same rpm 6700. The real nice thing is the 35ftlb tq it added through the low end. No other changes once so ever to engine.

Define low end?

[Old School]

I went to dual dommies and tunnel ram on my 438. We dynoed engine afterwards and engine picked up 54 peak hp at exactly same rpm 6700. The real nice thing is the 35ftlb tq it added through the low end. No other changes once so ever to engine.

How did the track et change before and after the dominators? What carbs did you have on before? How did the mph change? What kind of car was this engine in?

Thanks

[RW TECH]

The heads are pretty small for 540 CID at 6700-7000 RPM, and chances are the 750 carbs are also a choke.

You can put a vacuum gauge on one of the base plates & aim a smart phone at it to video record it during the run. A thin piece of yellow tape on the bezel, positioned at 0.5", would be a good reference in case the needle flutters around a bit. If it's pulling vacuum it's choked.

The moves you are making with the cam are basically insignificant, especially if the heads are as much of a choke as I believe they are. As an example, here is a dyno plot from an engine with big intake port area/small exhaust port area. Two cams are compared, one with 252°/276° duration @ .050" and 112°/112° lobe centers and the other with 248°/288° duration and 112°/108° int/exh lobe centers:

[F-BIRD'88]

Post all the data from your recent time slips.
May be some info there, to see what the car is doing,