SonnyinVA

will someone run my setup on desktop dyno or some other kind of program and see what you get?
i'd appreciate it.
i think most everything is in my sig, lemme know if you need anything else.
thanks!
Sonny

MrNuke

You need to give the exact spec of your stroke / displacement and airflow specs if you have tyhem to be exact.


[Modified by MrNuke, 1:12 PM 4/15/2003]

MrNuke

I entered the data vaguely into Desktop Dyno, and it came up with @420HP peak, and @510Lbs Torque Peak.. That cam seems to be a bit mismatched I think.. But liek I said, we need more specifics to be 'exact' besides Desktop Dyno isn't exactly on the $ when it comes to estimated HP..

SonnyinVA

4" stroke, 4.030 bore
ummm what else?
head flow numbers are here...


dang picture won't work. OK there it goes...
the head flow numbers are on the AFR site under AFR LT4 220cc competition ported

anything else?
that cam should be matched to my setup, i talked to dean harvey at comp cams and this is what he recommended. it is solid roller if that changes anything.
thanks again,
Sonny





[Modified by SonnyinVA, 2:42 PM 4/15/2003]

flyersfan1088

You can download Desktop Dyno for free at Kazaa

SonnyinVA

i've been having trouble with my kazaa.
is it too big to send as an attachment?
ashleyparks@***.net if anybody wants to try.

anybody tried pluging the numbers in? what did ya get?

CorvetteZ51Racer

I'll run it on Engine Analyzer Pro (MUCH better than DD) in the next day or two when I have more time...FWIW, that monblade throttle body is WAY too big for this motor. You'd be fine with a 58, and may have gotten away with a 52 (though the custom 54 I've seen before would've been best)

SonnyinVA

i appreciate the input and will watch for the results. what is a good place to get a program like that?
phil tobin put a 1300cfm TB on a similar motor he had in Hoover and picked up a tenth or something like that. i'm sure there is a way to calculate CFM required. anybody know what it is?

MrNuke

:iagree: DD did not change anythign significant as you switched down from the1300cfm to smaller TB..Since DD is pretty CRAPPY and I don't wanna run through hoops setting all the data manually, (nor send it to you as that is illegal), I'd guess you will see just around 500+HP with your setup...Dunno how reliable it will be though.. I will defenately NOT be a daily driver.. :lol:

CorvetteZ51Racer

CFM = displacement * RPM / 3456

This equation assumes that you have 100% volumetric efficiency at peak power, which is not the case on a good motor...a GOOD street/strip motor will have at least 110% VE, so take the above number and multiply by 1.1

SonnyinVA

i wonder if anybody has ever done a dyno test to see if the real world #'s back up that equation?
i think/hope the car will be more streetable than most people suspect. unless 600hp is considered unstreetable... lol (600hp being my goal) :D :D

SonnyinVA

hmmm.... ok 409ci at... let's say 7000rpm (just to pick a number)
i still get less than 1000. i get about 911 using 1.1
supposedly the 58mm flows 1050cfm, right. how accurate is that?

well, we'll see. i'll probably do tests at the track on test and tune night as opposed to dyno time. dyno time is just too darn expensive for that kind of experimentation.


[Modified by SonnyinVA, 12:02 AM 4/16/2003]

SonnyinVA

ok next question...
how do you calculate VE?
is there a good site/link with all these equations somewhere?

sinistervette

I've found that almost every form of equation for figuring cfm requirements for engines to be a joke. They might be fine for bone stock engines, but in the real world dyno testing and track testing I'm not a believer in them at all. There are so many factors that affect what cfm requirments will be that I've yet to see one formula that is right for most set ups. I'm talking carb cfm, but I've never flow tested any carb with fuel flowing through it just air, and I'm not so sure that the "air flow" of a carb is going to be much different than that of fuel injected"dry" set ups. To me air flow is air flow, and you need to have a set amount of fuel in that air flow to reach the correct air/fuel ratio. It should not make much difference if it is flowing through the carb, or sprayed in with the injector other than the fact that the mixture can be controlled better with the fuel injection. I'd like to see the guys that believe in the formulas for airflow try and figure out why my 335ci small block makes the most hp with a 930cfm holley on it. I started out with a mildly moded 750 that lowed 790cfm and switched to a 800 that had been flowed at 870cfm. I ran this setup for two weeks and still was having misfire problems above 7400rpm. Pulled the motor and took it to dyno shop with the origional 750/790 and current 800/870 to test. Found that there was minor loss of torque, which with this small motor torque is not even something to consider, but gained as much as 21hp with the 800 over the 750! Printout was showing a lean condition starting at 7100rpm and getting serious by 7600rpm. Came back home and started modifying and 850 to put on for the next weekends racing. When done my 850 flowed 930cfm, and after some jet changes and air box adjustments I had gained 6-7tenths/lap on a 1/2 mile paved oval. At the end of the season pulled the engine and dyno'd it once again before tearing it down. After 14 weeks of running, the 930cfm averaged 18hp gain over the 800 from 4500rpm to 8200rpm. The engine dyno'd 536.8hp@8200rpm. I can't find my dyno sheet for the 800 but the 750 dyno'd max hp 469@7200. The 850/930 was making 505hp@7200 and 521hp@7800. Once again my experience has been with carburation, but I do not think you will find much of a difference with the fuel injection. What would be cool is someone actually taking a super strong injected setup to the track with a few different tb's to see just what difference there is. Hey lets talk ski-down-it into testing out some different tb sizes on his 406! :cheers:

CorvetteZ51Racer

Wow. Ok, here goes. The reason you made better power with the bigger carb? The air bleeds weren't right for the your air demands on the smaller carbs. When a carb shows non-linear air/fuel characteristics, it's because the air bleeds aren't right. There aren't any off-the-shelf carbs out there (that I'm aware of) that allow you to jack with the air bleeds, because they're damn near impossible to tune properly without data logging, a wide band O2, and either a LOT of track time or dyno time...and air bleed requirements change with atmospheric conditions, just like jets do, so getting them right can't reasonably be done only with track tuning. That's why the Winston Cup teams (for example) spend SO much time in the dyno cell...making sure they have their jet/air bleed cheat sheets right for the track.

One thing that you learn VERY quickly (if you didn't already know it) when doing high dollar research on racing engines is that theory is a great guideline, but may not hold up to reality. But I'll tell you this much...the advancements that have been made recently in engine performance came from engineers using theory to guide the experimentation. On the airflow demands and the equation, IT WORKS IN THE REAL WORLD FOLKS!!!! Engine designers who know how to spec a cam use this as one of the equations in that process, so they can figure out how much air the engine needs.

Think about this...volumetric efficiency is the ratio of cylinder volume to fresh air/fuel charge that enters the cylinder, right? Ok, if you have 100% volumetric efficiency, then you're passing exactly the engine's displacement through the engine for each complete cycle (2 crank revolutions), right? Ok, so on a 350 Chevy, you flowed 350 cubic inches per two revolutions. If you were running at 110% VE, you'd move 350*1.1, or 385 cubic inches. This is the definition of volumetric efficiency. Ok, so how many cubic inches do you flow through in a minute? Well, that would be the number of rotations per minute (RPM) divided by two (remember, one "cycle" is 2 revolutions). Ok, so now we have 350 cubic inches (back to 100% VE) times, let's say, 9500 RPM. That would be 1,662,500 cubic inches per minute. Well hell, we don't talk in cubic inches per minute, we talk in CFM (cubic feet per minute). So there's 12 inches in a foot, so we cube that to convert from cubic inches to cubic feet, and get 962 CFM.

So, for sinister, he would need 335 CID * 7800 RPM / 3456 (that's the 2 revolutions per cycle times 1728 cubic inches per cubic foot conversion) multiplied by, let's say 110% VE. So Sinister's motor needs 831 CFM. Now, if he could find an 850 with proper air bleeds, he'd have the best throttle response he can get and best fuel metering he can get while still having the flow capacity for top end.

On carb flow rates, the carb manufacturers LIE about the flow rates...yes folks, they do. Why? Because there are circle track series out there that require a 390 CFM 2 barrel carb...by rule. The only way they can police it is by running part numbers with the manufacturer. EVERY SINGLE aftermarket 390 2 barrel carb I've ever seen on a circle track motor flowed AT LEAST 525 CFM on a flowbench at 28". The other thing is that there is a decrease in the flow capacity of a wet (carbureted) intake as opposed to a dry manifold.

Getting back to the EFI question, a 58mm TB is capable of flowing 1025 CFM at 300 ft/sec mean velocity. So the 409 spinning to 7000 with a 110% VE needs:

409*7000*1.1/3456 = 911 CFM

Conclusion? Yes, the 58mm would be big enough, and will give you better throttle response than the 1300 CFM monoblade (another discussion altogether).

Beach Bum

Sonny,

I think your set-up is going to be very, very strong....good head flow, agressive solid roller cam and a lot of the little things to make it go. As you know Phil T with Hoover with a very, very similar set-up made just about 500 rwhp with an auto and locked torque converter and a best of 1.45 60 ft, 10.64 et and 128 trap speed. Will probably be hard for you to match that et with your stick, but can probably get within a tenth or two and similar and possibly even better trap speeds..... but will probably take a while. Took Phil a year or two to extract every hp and was accomplished by ignoring old theories and simply letting the track results show the way.

But when you do get it dialed in, you should be in the neighborhood of 500 rwhp give or take a bit and that type of HP is capable of trap speeds of over 125 mph in a 3400 lb raceweight C4.

Regarding the Monoblade TB.... I remember when Phil put it in, he had his doubts, many theories told him not too.... but he did anyway and went out and ran his best et with it, I think 1st time out with it. 7000 + rpm bored and stroked LT-1's like lots of air. As far as throttle response with it.... not exactly sure on that, but 1.4x 60 foot times indicate throttle response shouldn't be too much of a problem.

To answer your original question in this thread.... similar combination has been run on the simulator before, I think you should realisticly expect 550 HP flywheel ponies with that set-up when it get it dialed in.... maybe creep up towards 600 hp.... but dunno.

Good luck and look forward to hearing the results.

cheers,
Beach Bum

black_89_vette

Hi there, I was playin around with my desktop dyno, and who knows I may have input some numbers incorrectly, but here goes.

I got you at 551 hp @ 6000 RPM
I got you at 531 tq @ 4500 RPM


EDIT---had to fix cam profile


[Modified by black_89_vette, 2:57 AM 4/16/2003]

sinistervette

All of the carbs had adjustable air bleeds and were set on engine dyno using the airfilter and air box off of my stock car as well as pulling outside air into the engine while in the dyno cell. The dyno shop was a sponsor of mine as well as I supply him with carbs for his engines that he builds for his customers. I have done some extensive dyno testing to monitor the changes/modifications that I've done to carbs as well as intake manifolds and cylinder heads to see just what benefits or losses are achieved. One other condition that a dyno, chassis or engine, can be misleading from is the fact that some air boxes give a ram effect at speeds on the track or raod that are nearly impossible to duplicate on a dyno. It's amazing at the amount of changes that can be needed to a set up on the vehicle at the track versus the same setup on a dyno. A good ram air setup is one of the major reasons for good dyno tests not actually being the best setups for track performance. At the time that I stopped racing I was working on a ram type outside air source to use on the dyno, but it never got finished. To me data logging at the track is the most accurate, most beneficial way to tune your set up. :cheers:

CorvetteZ51Racer

We've actually done that here. We have a Weiand 6-71 Blower (it was a spare laying around) mounted in the ceiling in line with some ductwork that comes down to the top of the dyno with an electric motor to run it. We have a coupling on a pivot that we can use to directly couple the blower ductwork to the carb and an adjustable bypass on the ductwork to allow us to control the pressure going into the motor to an inch of water.