hey man while your at it you might as well get rid of the disco brakes and start playing the drums.

 

i've got a 254/260 solid roller cam with the EFI in my car and i have no problems. how big are you talking about going? i have about 600hp naturally aspirated.

 

The smallest cam we have ever ran was a 264/260 isky @.50. With are larger engine we go with larger profiles with .450 lobe lifts. I guess what I am stressing is for a person like me, a racer, that has been around a while, will usually be more familiar with tuning a carbed or mechanically injected engine. Plus most race engine shops that I have visited are way behind the curve on the EFI stuff. Also, most really high end cylinder heads, like the 12X12 RP and the BD 2000 GB 2000 stuff, where the horsepower is really at, take a weird or custom made intake. This may pose some problems for the EFI, I do not know. As for my 434, it's a Rodek 350+ aluminum block, LA Enterprise Kryptonite 6.125 conrods, 4 inch Callies crank, JE pistons, Reed custom ground cam, Jesel shaft rockers, Del west titanium valves, brodix 12X12 RP, total seal gapless rings, and a Weiss dry sump pump with Peterson tank. All in all, too much!!, but to put a number on everything new would be in the $20,000 range. We are in a tear down phase now, I would like to get into an Oliver crank or even a LAE but the costs are pretty high. I would also recommend the carb for one big reason. At least with us, we change cams and gears and all sorts of parts all the time to match up better or to try something new. For the most part we end up close to the original build but we do stray a bit. For the people buying these, tuning the EFI may hinder the development. We try to make a point to grab the latest camshaft tech available every year. I mean, we are probably freaky about that, and it doesn't do much good, but it is something to think about. I have found being flexible to be the biggest advantage, far ahead of power when I go to the event. Sonny, it sounds like you have a great set up! How long was the learning curve on the build and do you think that more is there for the getting, or do you think you are at the limits of either displacement or induction? Sounds cool though I would love to see it run sometime, do you have any track video. I get asked that all the time and the people just stare when I tell them I am too poor for a cam. lol Could the shop that started the post chime in on what their customers are looking to run as far as class and performance. I think everyone here is right, the difference being the performance level that we are talking about. It appears that for the moderate to high performance levels the EFI can work. I would be a tough sell on convincing that this set up would work on our engine though. Oh yeah Road Race all the way for me!

 

haha! i know what you mean about the camera. i have an old hand me down analog hi-8 cam that i got for free... works ok for my purposes but not too easy to post or convert to digital. i'm thinking about a digital cam for x-mas.
i know there is more left in the motor. i definately need some bigger headers and still trying to maximize my tune. i'll be starting over at square one soon, because i am installing a 300hp nos shot for when i am doing land speed racing...
hopefully, i'll have some sweet videos to post in the new year...
see ya!
sonny

 

Nobody can argue the fact that, compared to modern FI, carburetors are pretty crude instruments. Easy for the average mechanic to adjust/tune, but stone-age.
How many moderrn, purpose-built race cars (Audi, Porsche, Saleen, F1, C5R, C6R, etc.) are running Holly double-pumpers??
The lateral loads experienced in road racing dictate FI.

That's why when carbs were first mentioned, I assumed he was talking drag racing.

Larry
code5coupe

 

Yeah but the purpose built cars have the luxury of the money is not an option clause. If your fuel system is up to par you will never starve a carb for fuel. Also, the purpose built stuff has the advantage of taking their engineers to the track with them to set it up, while having many of them back at the plant working on other cars. With F1's budget I would run EFI, but for the performance difference that may be found with an injection system at these levels, I do not think it is cost affective for this application. Just my opinion. Racing is not always about being cutting edge and high tech, look at NASCAR, they run pretty well with their carbureted set ups on little gas eating engines.

 

Talk about lucky! I am so glad I brought up the carburator vs. fuel injection topic.

Obviously, we have very little experience with V8 race motors, and were just assuming that the principles which apply to 4- and 6-cylinders would carry over. But just to clarify - we are not looking for street-style characteristics like cold-starting, smooth idle, or fuel economy.

With the smaller displacements, our experience has been that "stock" FI systems were designed for street driving, and even the "performance chips" available offer only modest power or torque improvements. There are then two ways to circumvent this problem: replace the intake system with carbs (relatively inexpensive, and straight-forward); or build or buy a highly specialized fuel injection system (very expensive, beyond our capability, and difficult or impossible to adjust.)

We obviously need to look more closely at the tuning options available for FI on the LT-1. We welcome all the suggestions.

Incidentally, of those "purpose-built" cars Larry mentioned, I believe only the Formula 1 cars and the Audi (prototype) have the OPTION of using whatever fuel delivery they choose. By regulation, all the others need to use the homologated system that their street "twins" come with. And certainly McLaren or Ferrari or Audi are not taking their injection units off some dealer's shelf, and reprogramming the chip.

Thanks again to everyone - we are headed back to the reference books.

Ed LoPresti

 

Ed,

You have to appreciate that the "stock" FI systems on an LT1 can support upwards of 700hp! They are not weak!!!

All you need to do is install a larger injector to match and remap the fuel curve. A higher volume fuel pump would help, too.

It's really quite amazing what the factory injection system can support.

And even in a race car, drivability is so very important. It's one of the reasons why cars like the Audi R8 is so very successful! DRIVABILITY!!!! 911's are so successful because they are not peaky.

A well tuned FI will give great performance and still be drivable. The last thing I would want, even in a race car, is peaky power delivery and poor tractibility. It means you are fighting the car, and not racing it.

The upside of the later, 1994-1996 Corvette, is that it is programmable via a handheld device. and the CPU is that much faster, too. As is the available memory.

It's not that I don't like carbs (well, I don't, really), but I feel they have their place, and when a good FI system is available, I don't see a reason to go backwards.

I will say this, don't compare the GM FI systems with others... at least not in regards to performance potential.

 

Deak,
Modern FI is not just available to high-budget factory teams...YOU AND I HAVE IT ON OUR CARS!! It works, and works better than carbs.
And don't come back and tell me FI is only required by emissions....emissions (just like driveability and power) is dependant on the perfect fuel mixture at any given moment. Only FI can deliver that.

As far as NASCAR setups and carbs; if you think for one minute that every NASCAR engine builder would NOT go with FI if the rules permitted it, then you are mistaken.

If Ed is more comfortable with a Demon or a Holly, then that's what he will offer his customers. I'm saying some customers might ask for a system that is more up-to-date. I know I would.

Larry
code5coupe

 

My point is just what the shop stated earlier, when you are hardcore racing, not just tooling around on the weekends, parts are going in and out constantly! Changing cams, rocker ratios, compression, fuels... you name it, gets changed for different tracks and regulations. I just feel that using the EFI on this type of app will require a support team. You simply do not have the time to drop the fluids, freshen the engine and fix what you broke the week before plus freshen the brakes and tires and set up your EFI to match any changes that you make. For guys that want to try to have it both ways fuel injection works, but for those of us that just care about running fast, the carb works better for us. As I have said before, I would still have doubts about running a cam that will pull hard to 8500 with the EFI. These cams push a ton of air back up through the intake below 2000 ROMs and have a tendency to freak out the sensors. If there is a way to get around this then it may be worth playing with for a team effort, but not for the individual racer. There are just not enough hours in the day as it is. Also, you are talking as if the carbs will not work or not run, they drive perfectly fine for me and I have had no problems getting around the track.

 

Deak,

But that is SO the advantage of EFI - once you tune for a specific set of regulations, the tune can be updated to match at the drop of a hat!

also, the tune is not so dependant that if you go from 1.6:1 rockers to 1.7:1 rockers that it won't run ok. There might be a few ponies to pick up, but they are not that critical... and I doubt a carb will take better advantage.

As for cams that do what you are describing, EFI can be programmed to get around this... and yes, there are cams better suited to carbs, and you would not use those cams in an injected engine... it's that simple. The same is said for an EFI performance cam... you would not use it with a carb.

I stand by the advancements of EFI.

Also, if you want to learn more about EFI, how it works and why it is better, check out "Corvette Fuel Injection and Electronic Ignition: 1982-2001," by Charlie Probst. The book is avaliable from Bentley Publishing.

Just so you know, F1 uses EFI... and those motors pull to 19000 RPM without sensors freaking. I know... those are hard core systems, but the point has been made.

The only limitation EFI has is a lack of understanding.

 

Here's my take...

1) It's not... For my drag car I've completely eliminated the ABS system, all of its wiring, its accelerometer, and re-plumbed all of the lines... Weight savings of almost 40 lbs. You can simply unplug the system and the pump will no longer pulse the brakes but your "Check ABS" light will come on (who cares?).

2) You can completely remove it and utilize a new accelerator cable from a car that doesn't have ASR.

3) It's not...There are several companies that mfg direct bolt-on coil over kits for C4's. Or you can piece one together from QA1 as several people on here have done.

4) None whatsoever... Unless you plan on keeping a fuel level guage; if you do Auto Meter and other companies make new sending units that are depth adjustable and use a GM voltage signal.

5) Why???? The EFI will give you better economy and more consistency on the track. As far as I'm concerned carbs are nothing more than a big, semi-controlled air/fuel leak sitting on top of the motor...But that's my opinion!
-Jeb Burnett, Pres.
Deep Freeze Cryogenics, LLC
www.deepfreezecryo.com
(866) 324-CRYO

 

You obviously are very unfamiliar with modern EFI systems if you think this way... First, EFI doesn't give a damn if you're running 10k rpm...The maps are scalable up to 20k rpm on most systems. The air being pushed back into the intake is known as "reversion," and is from radical cams with a lot of overlap. It is true that a lot of overlap will throw the manifold air pressure (MAP) sensor into hysterises; but most RACE vehicles do not run a system utilizing a MAP sensor but instead run "Alpha-N" mapping... Alpha-N uses the throttle position sensor (TPS) to determine load; I'm one of those that uses it in fact because of my big-azz cam and heads. Where you have issues with this system is in tuning part throttle conditions for drivability but on a race car there isn't much concern with that.

You make a case that things on a racecar are changed quite often and that is a reason NOT to use EFI... Well, personally I think that is the EXACT reason to use EFI. Lemme give you some background first; I run an NHRA Super Stock Vette and have also (at various times) campaigned cars in the NMCA, NSCA, PRO, and Southern Outlaw series so I know what changing combos for different tracks and thrashing in the pits is all about. It would be a ton easier with EFI, but unfortunately the NHRA simply won't let me use it on a '66 BBC Vette so I'm stuck with a damned DaVinci 780 vacuum secondary (the only carb allowed for the factored engine we run)! Now, on the other cars I do run EFI and it makes tuning much simpler (and cleaner). Let's say the weather conditions change: instead of having to go through my racer's log and find what jets and air bleeds I run for that particular condition and get dirty swapping them out and HOPE the tune is right, an aftermarket EFI system can utilize a MAP sensor (even those running Alpha-N) to compensate for weather fluctuations. Now, let's say you change gearing for an 1/8 mile track and you have to go in and adjust for that...No problem, look into your database for the map you use on this track and hit a key...Voila, instant tune!

Now, the argument that "for those of us that want to go fast carbs are what works" just doesn't hold water. I've spent more hours in dyno cells than most people can even count and without a SINGLE exception EFI has ALWAYS made more average power and torque...Note I said "average" and not "peak;" that's because average power is what wins races, not peak power; particularly road racing! Now, you and I have similar engine combinations and I would bet that my motor not only makes more power but has a BSFC (brake specific fuel consumption) less than 2/3's of what yours is which means more efficiency. Man, I can tune a carb (oops, I mean air/fuel leaker) with the best of them but if given the choice and opportunity I'll take EFI over one EVERY time in a racing environment. FWIW: A couple of my customers are MAJOR, WELL-KNOWN NHRA Pro Stock racers and they've been doing R&D with EFI for about 8 years now in the belief (and they'd know) that NHRA will allow EFI in the next few years for Pro Stock (that is once the NHRA techs figure out how people can use it to cheat). These two guys have been known to spend X-mas morning in the dyno cell, they're that serious (if I could tell you who they were you'd know); they've found more power, more consistency, and obviously more efficiency with EFI and are chomping at the bit when the NHRA says "okay!"

I do have one question for you, Deak... After reading about your combination, which is very nice I might add, are you using a tall-deck block? The reason I ask is that with a standard deck height, it's impossible to run a 6.125" rod with a 4" stroke... That would give you a compression height of .895"... The shortest piston made is 1" so you'd have a "little" piston to head contact...
-Jeb

 

I believe we where talking about the LT1 form of injection. The hilborn injection that is mapped and converted to electronic is good we have just heard that it is hard to map out for the part throttle mixture. In drag or oval track this is not a concern but in Road is tends to be. If we were running alcohol it would be less of a tuning issue but you are right, those systems are very good, I may run one with EFI or a barrel valve next season, it's just hard to find one for the 12X12 RP and may take a while to set up. I think the discussion was on the factory like system and I do not know if it is possible it is to set them up like the aftermarket systems. Are you talking about a LTX system or a converted hilborn or something else? We are not really familiar with anything other than the Hilborn stuff but that was a sprint car setup. Also to answer your question it is a tall deck block, .260 tall if I remember right.... What is your combo like and who did you get your injection through? Also does this run drag or road, sounds like drag?

 

Hilborn? Not talking anything like that; you can map a factory ECU with TunerCat software (for PROM vehicles) or LT1/LS1 Edit and HP Tuners for LTx and LSx... The systems I'm speaking of are just the EMS's themselves, the engine management system, like Accel DFI, FAST, etc.

Why go to the expense of running an IR system? Plumb your intake for EFI; it's just a matter of TIG'ing on bungs and building fuel rails. No sense in going crazy, just use your carb manifold. A single T.B. in the 1300-1500 cfm range will be fine for your combination; either get a 4v model or an adapter plenum for a single bore t.b... Then all you need is the fuel system and an EMS.

My combination is a std. deck block 440" (4.185 bore x 4.00" stroke) Dart Little 'M' based motor running SB2 cylinder heads. I built the engine and fabbed the EFI system as well. I used to run Accel DFI 6.32 (old engine combo) but am now running FAST. The motor is a drag motor set up for N2O... But a cam with a narrower lsa would put it in perfect trim for road racing; hell, the cylinder heads are NASCAR sourced.
-Jeb

 

Cool, how much problem do you think there would be with getting the part throttle operation right though. My engine guy has always steered us away from the injection since it is hard to get it tuned for part throttle. I do spend a lot of time at part throttle especially through some of the tech sections of the courses. As you can imagine, you don't always need 800 hp. My engine guy has voiced concern about this; he feels that over the course of an endurance event we could hurt the engine if the tune is not at least close in these areas. Have you found the part throttle operation to be adequate enough to avoid any damage to our engines? I want to make it clear; this is the only real issue I have with the FI because what I have found/hear is that you cannot easily get the proper tune here. For drag and oval track they are the best, but you are on the throttle all the time so the issue with part throttle does not apply. If we could reliably get the full spectrum tuned out well enough I would jump onto EFI with our budget, but I can not afford to be down much due to breakage as running the car is expensive enough as it is. What is your take on this situation Jeb, it sounds like you have a ton of experience with these systems, can it work well for this app? Are the part throttle issues you mentioned in your first post what we are talking about here and can they be overcome?