New 550 cube 440-1 combo motor, how fast?

Figuring the DA will be 2700 at the time i run, car weighs 3010 with me in it. Methanol fuel. Dynoe'd 926 hp, actual dyno hp with my headers and aircleaner was about 919hp. Torqueflite with 2.45 low, 4.56 gears, 33x 10.5 x 15 Hoosiers, 6300 stall set to shift at 7450. Ok, your best guess? I would think a high 8.7x (8.779?) at 152 would be great with lousy air andxa weak 60 ft of 1.27 or so.

3010@919hp>

60 Foot E.T. : 1.20
1/8 Mile E.T. : 5.46
1/8 Mile Trap Speed : 124.53
1/4 Mile E.T. : 8.65
1/4 Mile Trap Speed : 155
less your 2700DA I'd say your in the ball park.

Gonna guess 8.79???

My guess is 8.68 at 153mph with a 1.24 sixty foot... if the air is at 2,700 feet and humidity is no more then 30%.

My Carr’s best pass was in 14% humidity where the dust hung in the air above the gravel road to the track. Alky cars love dry air!

Good luck Greg!

Well, the first pass was kind of a fiasco and the second was worse. I had idle problems and never got the rpms up on the first launch. 1.278 60 ft, 8.888 at 150.50 mph. Turns out my idle adjustment screw was loose and it backed off causing me to have to fight to keep the motor running. Round two and it blew the tires off and the 60 ft went to 1.334 but the back 1/2 of the run was very close ending with an 8.987 at 150.15. More info later
Da for both 2500 ft

3rd pass at 5pm. 2800 da. Launched fairly hard and moved right. I managed to get it straight but it was almost time to lift. Still went 1.274 60 ft but slowed to 8.948 at 149.71 mph. Vacuum has been 4.2 inch all runs. 1/2 shift at 7540 rpm, 2/3 shift at 7340rpm both on the same timer (rpm set at 7250) and airshifter. I weighed the car again and it said 3035 . Don't trust others to take readings!

I didn't realize you were running such a narrow slick! That is a lot of power to the wheels (4.56 and 3-speed trans) for a 10.5 tire bracket racing.

FWIW,
Using my Logbook power calculation for that run and 3045 lbs shows 860 hp actual (919 corrected to STD) based on the ET. I think the mph is a tad slower than expected.
Weight / (ET/5.825)^3 = 860 hp
I had to make up the weather to estimate the 2500 DA you posted to get the STD correction.
EDIT: Sorry I put in the wrong weight (3035 vs 3045). These Darts can be bricks in the wind hurting mph. But I know you will have better runs. Keep at it!

The Moroso chart shows 795hp for 150.5mph@3035lbs....... and that speed equates to an 8.98 ET.

So, on that day, at that track......... the cars performance is about 86.5% of the STP corrected power numbers from the dyno.

Based on the fuel flow and bsfc numbers on the dyno sheet, the uncorrected hp on the dyno was about 833hp, and the heading shows it was in 3077ft DA air.


Based on how I remember things going for you during some of your last outings, I’d say if everything in the valvetrain is still “good to go”, I think that would be a victory on some level.

Something else I can add.......

I have seen it before where the best tune for power on the dyno didn’t end up being the fastest way down the track.

I think Greg made some fairly sizable changes to his tune on the dyno.

If the numbers from the track don't get to where he thinks they should be, it might be worth trying to move the tune up in the direction of where it used to be....... and see if there are any positive signs on the time slip from that.

Sunday!!
I had a few issues, oil drips, fuel leak, so after spending an hour under the car looking for culprits but not really nailing it down, I decided to run the car with no hood, just the scoop. I didn,t run the base plate for the aircleaner either. The 60 ft was the same at 1.275, the incrimentals are 3.631 330ft, 5.638 660ft, 7.374 1000 ft, 8.854 1/4. So with a 2400 DA it ran 8.854 at a weight of 3012. (no hood, no aircleaner or base,)but the mph is what surprised me! 154.32 mph! 23 pounds less weight wouldn't account for 4 mph, so it sure must like that open terminater/scoop combo.
Launch Rpm was low at 4,000 to stick the tires and it worked. I had the shocks set too stiff on extension for the 8.98 pass and it spun badly. I miss quoted the 60 ft earlier when I mentioned the 8.98 pass and put 1.274 by mistake. it was 1.334
So this is what I take away from the weekend.
1 60 ft probably slow by .02 to .03 because I am not hitting the tires very hard, only 4,000 rpm. Full stall is 6300.
2 I set it up fatter than the dyno for safeties sake, and ran an .084 main bypass. Smallest on the dyno was a .090.
3 shifts happened at 7540 on the 1/2 and 7340 on the 2/3. Trap 7350 on the 150.50 mph run.
Dwayne, I agree there is more there, probably wants to go leaner? I didn't check the lash but since I only put four runs on the car and it ran up to snuff I assume you are right- your method of setting lash may have been what my program needed all along. I in effect set them .005 tighter than I used to. I measured an intake lobe every couple of degrees to learn about the cam. On my cam right at the spec'd lash the ramp speed doubles so now I understand why Jones said no more than .002 looser than spec! Spec is .019 intake hot, I set them .011 cold with a heavy drag, putting me .002 on the safe side.

Nice job Greg...You will get it figured out.. Our track temp was a bit over 150* today and I think the air around noon was 4300 DA...

Too hot!

It was toasty indeed! Jeff and Mike should be getting home soon...

Update----- Air density online says 3113 density altitude 91.22 air density at the time of the 8.854 run at 154.32 mph.. So, My Raceair Pro is reading 613 low at that point? If so that makes me feel better. With a speed of 154.32 and 3113 DA/91.22 AD It sounds like I will be running a fair amount better with some great air , tuning and chassis work! Now if I go on a diet,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

Personally I'd trust my own weather station over Air Density on line.
Doug

question: is 4 to 5 inches of vacuum normal for your engine program?
??

Exactly right.

l must still have air leaks somewhere. Before it was 10 inch.

Glad to see you got it out to the track. Like Dwayne says the dyno tune is rarely the fastest way down a racetrack. Its a good baseline for sure. Interesting the MPH increase missing the hood, scoop but more importantly the base. I would be looking at that combo for sure. It the scoop sealed to the throttle body?

Al, the throttle body is exposed to air from around the manifold, no seal. So i will try it with an aircleaner only next time with no scoop, then the scoop and aircleaner to see what all is making power and what is not.

Nice work Greg! once you figure out the best scoop set-up there's gotta be something more in mph. Even at 1.27 the ET is going to suffer this is probably a combo that would like a taller first gear because i'm sure it's spinning down low.

I agree, it might like less low gear although my experience is limited. My only option would be to drop from a 4.56 to a 4.30 that I have on the shelf, but then I take away from the high gear charge a bit?
The 60 foots were all within .002 so I have to wonder if spinning is an issue. I still haven't tried any other shock settings or T.P. I have 30 inch ladder bars, Afco big Guns set at 10 clicks back from full stiff extension, compression at -6 from full stiff. It carries the fronts almost to the 60 ft clocks, wheeliebars are set very high and don't contact till eight to ten feet out. Car is 47 percent weight on back.Tires are Hoosiers 10.5x33x15. I haven't gotten a clear video from a friend that took a vid of the launch, just a very blurrie version he could text. Before with less motor I saw a best of 1.248 running 8.80s with a 15x33 Goodyear 2078.

Hey Greg, any reason you wouldn’t try a classic 14x32-15 slick? More tread width, less rollout so you can 60 foot better? I am running a 10.5w -31 because that’s all that will fit... With the 4.56 gears and shorter tires I am revving a bit more through the lights, but some say that is the optimum way to ET, by hitting the peak just after 1,000 feet if the motor hold on to the hp on the top...

Just some ideas...

Arnie

I thought I would try some lighter tires. The 10.5x33 tires way 13 lbs less EACH than what I was running. I need a tall 33 inch tire since I have a 4.56 gear. I have 14 inch rims, so my rational was I will be hitting the tire well with that wide rim, almost like the sweet spot of a bigger tire if you follow my logic. The edges on my 15x33s had a funny pattern, at least to my eye. Having put down three runs with 60 fts of 1.276, 1.274, and 1.275 I think it is going to get better. How hard do you hit yours/ Launch rpm off the brake? I only went up to 4,000 rpm this weekend.
The weather station I have is new to me and I quoted what I thought was DA, (2427) but it is listed as "perf density" Then further was a DA number that was higher. Rereading my weather conditions for the 8.854 pass at 1.54.32 I have -a correction of 1.0884, ADR of 90.7, DA of 3275 feet. Can someone shed light on the difference between perf altitude and density altitude?

Call the weather station maker direct and ask them
Please let us know what you find out

Cab, the performance altitude number is a new calculation Computec uses that is considered more accurate than the older Density Altitude. Performance altitude on Saturday at BIR in MN was 2427 ft. BUT the density Altitude, the number most of us are familier with, was 3275 feet! So i am pretty happy knowing i ran what i did and fat as it was tuned.
Computec tech guy said to go by the hp correction factor for best et predictions. For that last run it was 1.0884. Which with sea level conditions would lower my et to 8.704 from 8.854

HP Correction is a good way to compare runs to one another. Its based off current weather conditions against ideal weather conditions. The generally accepted standard being 0 elevation, 59 degrees, 0 percent relative humidity and barometer of 29.92. Many factors change how a racecar will perform for sure. Barometer and vapor pressure, grains of water seems to be the biggest. Obviously altitude plays a role but as you go up in altitude the barometer drops, generally 1.1" per 1000'. So its a very good baseline to compare one run to another. For instance in places like Vegas 1.12-1.15 is a typical HP Corr number. I have seen it as low as 1.09 around the Thanksgiving race and as high as 1.17 in August during the day. Which is mainly altitude and temp related as humidity is generally fairly low. I have never had the chace to run in .999 air or lower but we have come close in the Vette at Norwalk at 1.01. I hear that some of those east coast tracks in the fall see .990 HP Corr days

I have never seen Performance Corrected altitude number. Would be curious what numbers they are using to calculate that and see if the claim is correct. In my experience when it comes to prediction baro, VP and GOW are the biggest contributing factors for my stuff anyway. Outside of track conditions which in some places can be a huge part of it. Also have foudn being on the fat side seems to help repeatability as well.

Very interested to see how your next outings go with the hood/scoop/air cleaner testing. Have you ever considered going to a 16" wheel?

Al, budget limits trying different rims and tires at this point. IYO does methanol react the same way basically as gas, except just less?
One thing about methanol, when humidity gets real hi like over 96 percent, there is a major drop in performance at some point. Like .04 et loss, and no warning when that majic line has been crossed. So late night racing in humid climates can be tricky.
Computecs' comments were that the correction factor uses the same inputs as performance density calcs, and i get the idea that actual grains of water is a much better yard stick than a humidity reading, since humidity is tied to temp and varys a lot from low to hi temps?
I have to say, this info on perf density and correction factors makes me think my combo is close to what the dyno indicates for performance, especisely when you consider the slow 60 ft.
One thing i wonder about; 53.5 percent weight on the front, pulls the front up and carries it to the 60 ft clocks, yet only a 1.274 best 60 ft.
I reserected a post from 2016 where you and Monte both commented at length, and i am trying to absorb some of that knowledge in moving my program forward. I know some or a lot of what i "know" is probably wrong.

What does it 330 ft? Since it carries out to 60 ft maybe its clipping the 60ft clocks with the rear of the front tire. That would slow the 60 ft numbers.
Doug

First pass on sat 8.888
Sunday no hood or aircleaner just scoop 8.854
Both runs carried the front a long way out.
Another pass had a 1.274 but was headed for the wall and lost time straightening it out.

Greg, do you have the other incrementals?...like 330?

8.888 first pass.
8.94 pass car launched to the right, i could feel it slow on the landing, had steering wheel turned slightly to correct.
8.854 pass no hood or aircleaner. Note that it picked up exponetially each increment. All passes within 200 da

How many runs on the motor now?
Is it breaking in the rings still?

Dyno operater said the rings were broken in at 14 pulls or less. Made 24 on the dyno, so they are well past break in. Total of the dyno time, several warmups, and these passes.

For one i would want a back-up verification on the 154mph run...but i def believe the power is there for that and more. Next is the 330 is reflective of a 9.0/8.9^ and as the run progresses the 5.64ish gets into solid 8 zone ET's but that is where it seems to have another 'hurdle' in that something weird is going on with the air inlet track...Of course 60 fts are slower than they should be even for a 3000lb '880 car' ...it's likely spinning to near the 330.

IMO 60's are "slow" because its not with the front tire, speculation based on the distant video but sure looks that way. The converter is not helping with anything down low, especially the 330' numbers. Its clearly way tight for the combo. Better air will help that but only so much. I dont doubt its going to run much better but he has some issues for sure to sort through.

For the mph i ran the car is slow by .264 seconds in the 1/4. It is slow compared to the Walace calculater for 154.32 mph by the following.
60 ft .085
60-330 ft.094
330-660 ft .057
660 -1000 ft .026
1000-1320 ft .020

It really gets rolling at about 1100 feet and the accwleration graph shows it.
Couple of possibilitys. Bad airflow into the throttlebody, or fuel aireation. But the fuel preasure is rock steady on the graph. So,,, gotta be airflow plus maybe too much rpm on the 1/2 shift, as there was a definate drop off just before the shift. Other ideas?

Hey Greg, I have been launching mine at 3,200 rpm to try and slow down the reaction time and ensure it hooks... in 3,000 foot air, I just ran a 8.75 @ 154 w/ a 1.24 sixty foot. Need to adjust a few things to get back to my best times, but cant do much with the Air and higher water grains we are getting.

Cheers,

Arnie

Sounds like my idea of more launch rpm may go too high. Mine seemed to hook fine and carried the front a long way but 60 ft was 1.275.
At 4000rpm. Maybe i should start at 4000 and go lower.

Wont hurt anything to start at 3,200 rpm on the launch and go up by 200 rpm each launch to see where it is happiest... This gives it a run at the convertor which it may like?

If I try to launch it at 4,000 rpm it hits too hard and drives the rims down then when it rebounds, it spins... I need to have my Strange double adjustables, re-valved tighter.

I am done for the year up here in the frozen North. Are you able to get out again and keep testing??

Arnie

BIR Is open this weekend. Rock Falls in Wis goes late into oct i think. So ixwant to get to BIR at least.
Sounds like you need a lot more shock control in back on the hit, or less leverage. Ladderbars?

Look forward to hearing the next results. As Arnie says launch RPM is something to play with and is combo dependent. For instance we launch the heads up car from 39-4200 and that converter flashes to 8800. A lot of factors go into that for sure but it is something to try most definitely. It may adversely affect your reaction times dropping it as well. Just something to be aware of. I woudl start stiffening up those rear shcoks on extension for sure. Try to get some video closer to the car if possible as well.

[/quote]
Sounds like my idea of more launch rpm may go too high. Mine seemed to hook fine and carried the front a long way but 60 ft was 1.275.
At 4000rpm. Maybe i should start at 4000 and go lower. [/quote]

I am about to start experimenting with this. A lot of variables go into what a car likes to 2 step RPM I think. Some like a run at the converter stall and some don't. Converter setup and cam have a lot to do with it too. All my setups seem to get to the point that ET doesn't change but the RT does as you go higher, as long as it hooks, and when you drop RPM you get to the point the cam isnt happy.

Gearing also plays a big roll, trans and rear gearing. If you have a glide they usually dont like having the RPM dropped down so far, why you hear S/G cars at or above 6000. The more mulriplication you have at the hit the more tolerant they are of lowering launch RPM. The heads up car had a 2.24 first gear and 5.14 rear gear and a 29.5" tire, alot of SLR.

I run a Torqueflite and alcohol injection. The combo can launch effectively from idle to 5200 with big tires. But reaction times really slow a lot as rpm comes down i notice. Since I race off a three bulb tree it doesn't matter other than slowing the 60 ft.

For what it's worth my car is foot brake only. Geared 2.45, 4.30, 10.5x31. Leave RPM is how I vary R/T. Usually 2800-3200. This will most often put the R/T average in the .02x range. 60ft depends on how much ballast, track prep, and how good the air is. Sometimes air conditions and weight seem to vary 60ft more than track conditions. Slowed to 9.25 it'll 60ft 1.29-1.32 depending on ballast. Car can weigh from 3325-3500. Flat out in good air 1.25-1.26. My bet is good air is giving it some wheel speed. Pulled back it dead hooks.
Doug