540hp 383 in this month's Car Craft

[grumpyvette]

1fastz

if your making 750hp with a carbed sbc N/A (no nitrous,on high test gasoline with no fuel boosters,non-supercharged) useing 23 deg heads and a single carb , you should post more often , I sure need to ask a few questions btw mini rams are one of the EFI intakes Ive found that don,t work very well, the steath ram is far better

[Guest 1fastz]

the heads are not 23 degree I never said they were lol they are 18 degree heads.. 379 cfm intake 256 cfm exhuast.

 

however I just finished a motor for a customer who has a 13-1 compresion stroker motor..

 

it has 23 degree ponitac heads and makes 718 horses on the motor .. on 112 octane race gass.

[Oltmann]

Originally posted by 1fastz:

1 presure involved is not notworthy. Yes it atomizes the fuel better but it does not allow for time for the fuel to evaporate ..

I don't think that is true.

 

http://naca.larc.nasa.gov/reports/1933/naca-report-435/

 

I also can't see how cooling the intake manifold does anything but take heat out of the manifold, and put it in to the intake charge.

[Guest]

Grump why do you feel that the mini-ram basicly sucks in my eyes.they match those mass produced holleys,1000cfm 4inch runners,and you can close your hood.Myrons test are showing 600hp 350s,with out going to the airport to get fuel and is a VERY streetable set up,only diff I saw was chrome and it stood up pretty high,not knocking you by all means-convince me bro.Im happy with my L-98 going with zz-9x cam,fastburn heads,havent decided to stroke it yet but 550-600hp reliably(street)no trailer Queen,or three gears then go home.Hes already shot down the lingenfelter and holley and performer.I guess his next test should be against the stealth ram.

[SleeperZ]

I as well am doubtful about a cooling advantage the carbs are claimed to have. If the air is cooled by the evaporating fuel in the venturi, one would expect the same from an injector spray (even if it is closer to the cylinder). Once the "stuff" gets into the cylinder I would think it's all the same temperature, as there is no net heat gain or loss - the only exception is an intercooler on a turbo, where you actually are removing heat from the intake charge.

 

If my thinking is in error, please correct me.

[BLKMGK]

Geez, I should've read in here earlier

 

A few comments... First, I love EFI - programmable EFI in particular That said:

 

Carbs beat EFI in a couple of ways. 1) Cost for WOT $. In other words if you only care about WOT max power the carb setup will likely be cheaper. Note I didn't say that it would make more power 2) Carbs are easier to tune than EFI. Throw a few jets in there, twak a few things - that metered fuel leak will get you in the ballpark. For WOT it's likely even easier.

 

So, why do I prefer EFI? Well, a direct back to back carb vs EFI test will prove that the EFI makes more or equal WOT power and provides greater torque properly tuned. A Holly engineer who posts on another board, Grumpy knows him, did this test back to back on the SAME manifold and what I said above is what he found. 99.9% of these STUPID magainze tests use long runner torquey EFI manifolds against short runner single plane carb intakes - duh! Oh, the thing about fuel evaping in the intake to cool the charge is TRUE. The heat goes into the process of turning the fuel into a near gaseops state - same way NOS drops temps when it goes form liquid to gas. However with EFI spraying on the backs of the intake valves you do still get SOME of that effect. Go TBI if you really care about this but wall wetting will take away a good bit of this effect - carbs don't have a really big advantage here. Driveability - EFI stomps a carb. Sorry guys, properly tuned an EFI motor will crank up and run at O'dark thirty in the morning! It will have consistant A/F mixture across the RPM band and won't blubber and choke changing altitudes. Fuel mileage - carbs LOSE bigtime here. The A/F curve on my car onthe dyno was pretty interesting - lot's of dips and curves. Granted, the carb isn't tuned right but even if it were there would still be dips and curves as the various metering circuits and jets did their thing.

 

My car currently has a carb on it simply because it was easiest to setup and run the bugs out of the system that way. I'll be putting on a Stealth Ram or converted Victor Jr. later on. You've got a spiffy carbed intake that flows like mad? Cheap as dirt? Great! Convert it to EFI and reap the rewards. Don't need to worry about single or dual planes either, EFI doesn't care.

 

As for tuning EFI. I'm doing this now with an AEM system in my Supra and I've done it with an older DFI (ick). The newer systems ROCK! FAST is nice but somewhat limited IMO, DFI GENVII is better but support sux (last I looked) and it costs too much. Of the two I'd be hard pressed to choose a winner - support is IMPORTANT. That said - cheap W/B solutions are now here. For about $600 I'll have a full on W/B solution in my car that will read realtime A/F and give my ECU feedback. I'll know where to make changes to get desired A/F and in the future will be able to have the ECU self modify it's own fuel maps if I desire. Yeah, on the street WOT tuning is a PITA but this will help a great deal. Driveability must be tuned on the street anyway IMO, even a loading dyno would be hard pressed to do it "right" IMO. I'll even be able to monitor EGT in multiple cylinders (Ihave per cylinder timing and fuel control), light up warning lites for anything I want (lean A/F or boost too high fo rinstance), run staged injectors, 2step rev limit using fuel or spark, nitrous activation (and can pulse the solenoids if I were that brave), traction control (eventually), control boost vs roadspeed (!), and MANY other things with my AEM. FAST, DFI, and MOTEC have a competitor on their hands and it only cost me $1200! Yeah, sounds expensive but price out the competition For a race unit I'd have paid a little more to get the harness etc. but you get the idea - it's not a $3K+ system out of the box. I have $1800 in mine including W/B. FAST and DFI charge an added fee for their W/B as does Holley too. I smell a priceware coming by the end of the year

 

If all of this is too expensive or complicated look at the Commander from Holley. It can now take W/B too and it has some good features. Not many bells and whistles but it does the job. Once fully tuned it will get great MPG, start everytime, and have as much power and torque as a carb if you want it to.

 

Cost is EFI's ONLY downside, if WOT is ALL you care about then go carb because it's comparable under that narrow condition. On the dragstrip carbs will rule awhile longer (let them control boost and clutch with EFI and see what occurs!) and yeah NASCAR too but ask Formula 1 guys what they think of carbs Ask Rally racers what they think too, especially the turbo guys.

 

If anyone is interested in talking more about the AEM lemme' know in the EFI section. AEM is about to open their own BBS for talking about their ECU and it's going to get technical very quickly. The numbers of things this ECU can do is amazing but yes it has some things that need work - it's been out less than 6months. I'm using it everyday now (shrug). EFI is IMO the way to go if you can afford it, for a street driven car it just makes more sens....

[BLKMGK]

P.S. Is th enew Holley Stealth Ram too tall to fit under our hoods? I was considering that over my converted carb intake but if it's too tall... I do NOT want that super expensive mini-ram! Too much money when you add up the fuel rails and all

[Guest 1fastz]

1. ottman that test says nothig gabout the efect of cooling it is determining evaporation in the COMBUSTION chamber ..

 

the cooling efect takes place before the fuel ever reaches the valve.

 

2. intake wetting actualy cools the intake magic.. not the reverse.

 

fast limited ?

I dont see how you can say that.. you can tune individual injectors without aproblem and with the optional multi coil module individual cylinder spark as well.

There is no need to controll individual cylinder spark .. without we have been makeing 1600 + horses from 347 cube motors useing 91 mm turbos for a couple years now.

 

and a compleat fast system with wide band option is only 1800 .

 

I should know im a fast dealer .. I have a fast sequntial system on my daily driven street car a 900 rear wheel horse turbocharged 95 saleen.

 

as for dfi egen 7.. it SUCKS just like gen 6 .. fast flat out destroys anything i have used out there for tuneing ease.

any average person with decent knowledge of engine functions could tune a fast.

 

and i wont coment on the aem system till I see it in action proven one way or the other..

[Oltmann]

Originally posted by 1fastz:

1. ottman that test says nothig gabout the efect of cooling it is determining evaporation in the COMBUSTION chamber ..

 

the cooling efect takes place before the fuel ever reaches the valve.

That test proves that there is plenty of time for the fuel to vaporize before it is sucked into the combustion chamber. It happens in several ms in a pressurized direct injection environment!

[SleeperZ]

Just to be argumentative, and not leave Oltmann all alone here...

 

EFI vs. carb, if you are taking in the same amount of fuel, the same amount of air, and completely vaporizing the fuel, you will have cooled the air the SAME amount, regardless of the position of the piston as it starts the compression cycle. I know, I have no amazing or irrufutable credentials, but I did pass a college thermodynamcs class, so I believe I have a clue about what I'm saying (but no experience with carbs - and experience counts for a large amount, I know that).

 

In addition, if the vaporizing fuel is cooling your intake manifold, you are actually gaining heat in your intake charge, and the EFI will in fact be cooler than the carb system.

 

We may agree to disagree, and in the end it won't matter, but I think it's a good arguement.

[BLKMGK]

Been awhile since I researched the FAST but... Can it run 10 injectors, 5 coils, 2knock sensors (with each dedicated to specific cylinders), dual O2s (specificly dedicated), and switch from sequential to batch or bank without a trip to the manufacturer? Staged injectors out of the box? While running sequential can it run an idle motor? Can it run an electronic transmission? Monitor 4EGTs? Run a boost solenoid - closed loop? Datalog internally (512K on AEM)? Switch between two boost maps from an external I/O? Allow the user to specify sensor specs and scaling? AEM expects to have traction control in the future and Automodification of it's fuel map too.

 

Anyway, you get the idea. Yes AEM's box does all of that and more, it's a cheap MOTEC! AEM's biggest need right now is docs! When I priced the FAST with the options I wanted I remember it being higher than $1800, if that's the price for a full on sequential system with W/B that's not bad! FAST software is nice too, it's a little more polished than the software AEM licensed and modified (GEMS I think). The math library in the log analyzer application is powerful. DFI's looks good but I've found no user support community for it like I have for AEM, FAST, and Holley's system. Probably a better discussion for the EFI forum (shrug).

 

Gas cooling - yeah it's better for the carb or TBI systems. This has been documented but the superior metering of the EFI overcomes those advantages. Just the fact that you can make an intake without worrying about droplets dropping out of suspension makes EFI more attractive. Carbs have their place and they can make power. All depends on what's most important to you, EFI can meet and beat carb power but it costs. For WOT concerns only carbs make more sense IMO.

[Guest 1fastz]

Sleeper.. the fuel comeing out of a fuel injector is already in a near gaseous state ... and does not nearly cause as much endothermic cooling being converted to a gass as the pure liquid state fuel comeing from a carb does.

 

also the fuel injector will have far less fuel being used at the same power level .. hense the better economy you get with fuel injection.

 

vaporiation occurs as the fuel passes from the carb into the intake and no that in no way increases the heat in the intake..

 

the wet walls of the intake do trasfer some of the heat back as the intake charge comes past it but its been tested time and time again and every supercharger and turbo charger maker on the planet agrees with me that a fuel injected motor can not take as much boost at the same compresion level as a carbed one in a blow through aplication ..

 

and they all agree that the reason for this is the cooling action caused by the conversion of the LIQUID fuel to a gas as it enters the intake. up to 50 degrees of cooling in the case of a large carb and 10 psi + boost < more like 10-15 on a natrualy aspirated moter >..

 

so if you plan to dispute that fact then you better be ready to dispute the engineers at vortech ati paxton etc etc etc.

[Oltmann]

Originally posted by 1fastz:

it proves nothing of the sort i think you should look again..

I feel like I've fallen into a "nuh-uh" contest.

[BLKMGK]

Originally posted by 1fastz:

Sleeper.. the fuel comeing out of a fuel injector is already in a near gaseous state ... and does not nearly cause as much endothermic cooling being converted to a gass as the pure liquid state fuel comeing from a carb does.

Um, I disagree here. It's a spray of liquid droplets. It does convert but not with nearly as much energy transfer to the air. The MPG increase is from more exact and flexible metering. A carb isn't likely to be able to run 16:1 one moment and 11:1 the next. Okay, emissions cars stick to 14.7:1 but you get the idea.

 

also the fuel injector will have far less fuel being used at the same power level .. hense the better economy you get with fuel injection.

Okay, this is closer to my understanding.

vaporization occurs as the fuel passes from the carb into the intake and no that in no way increases the heat in the intake...

INCREASES heat? Someone said that? Umm no, it certainly DECREASES heat as you've said.

the wet walls of the intake do trasfer some of the heat back as the intake charge comes past it but its been tested time and time again and every supercharger and turbo charger maker on the planet agrees with me that a fuel injected motor can not take as much boost at the same compresion level as a carbed one in a blow through aplication ...

First I've heard of this and I'd love to see some proof from a manufacturer. An intercooled forced induction application is going to have air entering the intake at near ambient temps. The fuel distribution issues with a draw through far outweigh any vaporization advantages IMO. EFI is more flexible I think. I know some are successful doing this but I have to wonder if driveability is a PITA.

and they all agree that the reason for this is the cooling action caused by the conversion of the LIQUID fuel to a gas as it enters the intake. up to 50 degrees of cooling in the case of a large carb and 10 psi + boost < more like 10-15 on a natrualy aspirated moter >...

Heh, what's the discharge temp on a turbo? Figure something over 125degrees? 200 maybe? On a hot day a decent intercooler gets you back to ambient with less distribution issues. FWIW I intend to instrument both sides of my intercooler and datalog it to checkout it's effeciency. This monster ought to be awesome

so if you plan to dispute that fact then you better be ready to dispute the engineers at vortech ati paxton etc etc etc.

Umm, draw through vs intercooled or no intercooler? Personally I'll give up a little power to gain the driveability of EFI. I'd love to see some docs on intake temps on a draw through application. If it's below ambient I'll be surprised.

[SleeperZ]

Good debate guys. But I'm not budging on my point about the manifold getting cooler thing - if your intake is getting cold from all that raw fuel evaporating inside it, it is cooling the intake air LESS because some of the heat absorbed by the fuel is coming from the manifold and NOT the air charge.

 

This point I made was dependent on equal amounts of fuel and air between the carb'd seup and the EFI. This is decidedly not the case here though - the carb overfuels to deliver the right mixture in the cylinder, compensating for fuel dropping out of the mixture and not burning properly.

 

I will concede the point that because the carb delivers more fuel it certainly can cool the air more.

 

I guess you can tell which system I favor

[grumpyvette]

IF YOU GUYS WANT TO CUT DOWN ON THE AMOUNT OF TYPING........the short version is...IS SO..IS NOT...IS SO...IS NOT

[Guest 1fastz]

it proves nothing of the sort i think you should look again..

 

it proves that the fuel vaporaizes in the cylinder.. BUT that is when the fuel is being compressed and the cooligng efect because of the compresion is negligble ..

 

better try again

 

Maybee i should explain this a little better

 

WE are refering to the temperature of the intake charge NOT how well the fuel is atomied in the combustion chamber..

 

the fuel that is not alreaydy vaporized in a carbs intake charge will also vapaorize in miliseocnds once it hits the host combustion chamber..

 

HOWEVER the fuel that has vaporazied as it travels to there has caused a large cooling efect.

 

IF you doubt this how about you go here.

 

http://www.procharger.com/chevy.html

 

and i qoute

 

"Carburetors deliver the vast majority of the fuel in a liquid state. As this raw fuel atomizes from liquid to gas, a chemical state change actually occurs. Due to this endothermic reaction, which draws heat and cools the incoming air a carbureted motor can safely run more boost than a comparable EFI motor. The carburetor, in effect, acts like a mini, "intercooler", lowering the temperature of the supercharged air entering the cylinder by 25-50°"

 

care to argue withe the most advanced supercharger company on the market and the engineers who work for them ?

 

the verry aguement you are makeing goes AGAInST YOURSELF fuel injectors deliver the fuel in such a highly vaporized state to start with under high preasure that there is verry little endothermic reaction its almost a vapor to start with..

[Guest 1fastz]

ROFL grumpy

 

Oh and back to the original posters comento n the car craft motor.

 

its a grenade with the pin half way out.. cheap parts at that power level dont live long.. not to mention they left a TON of stuff out on the cost exspect to paya bout 5800 for a motor like the one they built.. starting from scratch and havieng to pay taxes etc.

 

then add in the fact that its being pushed beyond what the parts were realy built for power wise ..

I doubt that motor would live a long life if pushed hard with the parts they have in it.

[Guest Anonymous]

First of guys I want just 10% of your tire bugget. 500 horse power on 2600 lbs street driven car ? Sounds like alot of rubber smoke to me . Now as for the debate of carb vs EFI . Come on TF said no to cumputers for a long time because the rest of the car couldn't keep up . Nascar says no because rules tell you to use this carb number . F1 says use anything you want , and cuntrol power by limiting engine size . If want to get the car on the street run a carb , if you want to spend lots of money and watch "F and F" buy all the fancy stuff . No my car doesn't run yet and no I haven 't pick an engine comb.

 

TM

[Guest Anonymous]

If you wanna see smokin tars check out the thread posted on here " i finally got out there and did it"