No where in my posts did I say you were wrong. Just like the tuner in question never said "30 pound injectors will only support 350 horsepower".

and if "he is full of ****" isn't instigating a pissing match, I would like to know what is.

Now if you want to get into a pissing match...
If you were more concerned with providing valid content (which Jesse does) and having a meaningful discussion and less with throwing disparging remarks around and upping your post count, you might have read the complete post.

 

Yep that's me, I'm never here to help, just to up my post count.

Once again I seem to be the only forum member not entitled to an opinion. I'll make your life easier, I won't comment on this thread anymore so I won't say anything that offends you.

 

Guys....I think we are all basically saying the same thing......but something that always gets lost in these posts is the "average guy". Average guy being the guy that builds are get a 383, and is dooped into putting 36# injectors in the car. This average guy doesn't have the knowledge or the equipment/resources to tune the car to the 9th degree to get the bigger injectors to work. It takes a certain skill set and definative game plan to get them to work, and once that is done, they will run fine. But they will not run any better than the 24#er will. They will not give you more or less HP than the 30#ers will. But they will take more of your time, and get MANY guys frustrated to the point they sell their car or dred driving it.

Those are the reasons I try to voice my opinion. Maybe I am lazy or afraid of my wife.. and figure if I can reach my goal with 1/2 the time, why waste the added time it will take, to get to the same point?

If you read my MAF vs SD post, that is the same conclusion I drew with that Testing. Perhaps with another season and 1/2 I could get the SD to do exactly what the MAF is doing. But why? If the motor is running its max, that computer is not going to help it get more air in to make more power. I enjoy going to the track and testing, but I would rather go there, relax and make my time runs - get a good feel for my dial, then go several roungs knocking all-out racecars out of the running in my street driven car and take home some $$. Testing new stuff is exciting and fun, but as I said in the other post, I have over 1500 dollars investing in hardware/travel/entry fees etc trying to make this SD system work. I thought it would have run better. But now I see it as an uphill battle to just back back to where I was at the first time off the trailer.

That is what I believe needs to be EXPRESSED in this big injector vs small injector conversation. Remember not everyone has time/$/resouces / resolve to get their setups running. That to me is a VERY important aspect that needed brought out.

It was a good discussion and both sides have valid points. I always suggest to new engine builder to copy a proven setup. BeachBum had a whole page that I am more than willing to host for him, that had some killer setups. Following these combos save many $/time. Venture ot into no mans land, don't complain when you get lost.

 

Wasn't it Ludwig Mies Van der Rohe who said "Less is more" and It was Bob Weir who said "Too much of everything is just enough"

That is exactly what we have here.

The debate here is going very well, but I think less quoting of other's comments not related directly to the argument in question would be better.

 

I've never quite understood the merit of a roadcourse being different than a dragstrip when talking about vehicle acceleration. If you're coming out of a tight turn at 30 mph, and you have a hard 3000 ft acceleration straightaway, I would think you would want your car to perform to its peak in your 30 - 170 mph dash regardless of if the track you are racing on is called a dragway or a speedway. Most of the same principles that apply at the dragstrip, would apply at your speedway.

I would imagine the differences would be you gear appropriately for the primary track you plan on competing at, of course a really great set of brakes is extremely important on the road course, in addition, the chassis would obviously be set up stiffer, which as we know doesn't work at the strip perfectly, but the motor.... what would you change ?? If you're going from 30-170 mph, you're not working in just a single narrow rpm range... you're obviously having full gear cycles, thus you're using the entire pulling rpm, which will typically be 1500-2500 rpm.... same as your typical dragstrip motor.

I think road course racing is really cool stuff, and for you fellow Corvetteforum members competing in this venue.... I say Good Stuff !!!... and I hope you win. I hope to one day compete in some roadcourse racing as well, but I will say, I'll take my car to the dragstrip first to tune it to "accelerate hard" and base my results more on trap speed than et considering my roadcourse chassis probably wouldn't give up the great 60 ft et's..... once I'm sure I'm getting all I can out of it, I would then logically feel confident I'm also getting all I can out of it at the roadcourse.

Regarding the issue of having to run your car hard for 30 minutes continuous vs 10 or 11 seconds at a time.... this only tells me to run a "darn good" cooling system, and if the temps are still going to climb up to the 220 area, I might want to take a couple of degrees timing out before the session starts and run some good gas..... other than that, what does that have to do with what size fuel injector you're running? Your Fuel Pump and Injector combination either have the ability to provide enough fuel at all usuable rpm ranges... or they don't.

I don't know the answer to which is the best injector for somebody's xyz motor.... but I will say strong evidence is supporting that a 24 lb injector is sufficient to power a 3400 lb 434 equipped 6500 rpm C4 to just about 130 mph traps based upon a couple of forum examples.....until somebody improves upon this performance with the same size motor or smaller with a similar raceweight.... we've gotten nothing else to believe.

But I dunno...

cheers,
Beach Bum

 

I don't ask a whole lot of questions on the forum but the few times I do wars start. I guess it's just me Will switching to sequential injection really give me that much more hp? Should I switch cams to take advantage of the big heads? I don't want to switch heads and manifold. I would like to make this equipment work a little better.

 

Sorry, I neglected to comment on your original post in this thread.... my opinion, 200 cc intake runners that flow over 280 cfm are not hurting your 383, especially one equipped with a miniram that should be revved up a bit. 350 rwhp isn't bad, and quite frankly from a dragstrip point of view is enough to take you into the mid 11 second area if you properly optimize your short times.... but I think you've left some power on the table somewhere, and with 30 lb injectors, thats probably not the problem. (Whoever put those 48 lb injectors on your motor outa have their wrenches confiscated !!) .

I'd look at the little things.... start with valvetrain... which is very, very important, if you have weak springs or lash is wayyy out, this will kill HP, especially above 5500 rpm. Even things as simple as the age old problem.... is the TB opening all the way at wot? This will easily chop away your power.

Without knowing your exact cam specs its hard to say exactly where you should be, but for a reference, if you go to www.tpis.com within their engine development section, the last motor they have listed is a 383, miniram with a ZZ409 cam which is a .520/.520 226/226 @ .050" cam, which sounds like its similar to yours. They advertise a hair over 500 hp with that cam... which would probably be around 400-420 rwhp depending upon variables. Thus, it sounds like you might be missing some power.

Personally I don't think you'll pick up anything going from 2.5" exhaust to 3" exhaust... or at least I didn't with my 383.

As another side note... For what its worth, I've heard nothing but good things about More Performance, although I've never done business with them.

The last thing I have to say.... don't go and spend a wad of cash changing things based upon what a dyno spit out. I've seen big enough variances on dyno's to know that you might want to throw your dyno sheet in the garbage. Instead hit the dragstrip.... that'll tell you without a doubt if you're in the neighborhood of how strong you should be, and it'll be a lot more fun too. I'd personally guess, with a 383 mr, good flowing heads, hyd roller cam and roughly stock raceweight you should be able to trap somewhere around 118 mph to start with... if you can't, then you might want to go back to square one and figure out where that power is.

good luck.

Beach Bum

 

Good Stuff! Let me see if I can answer some of the points.

Very few courses are designed where you are seeing speeds from 30-170mph. Most of the time a Corvette's motor will be at it's upper rpm range. (In my case from 3800-5800 rpm) Very few courses require rowing up and down in gear more than 1 gear for each corner. Driver skill and suspension setup are much more important than maiximum engine performance (99%).

As you mentioned cooling is absolute. Not only coolant, but transmission, oil and brakes. (In some cases differential also). Due to the length of time spent on track, temps are high everywhere to include inside the car and the engine compartment. (coolant 220-230, oil 240-280, brake fluid 300+, engine compartment 180+, etc)

Every piece of equipment in the car most perform consistently throughout. Any minor component failure is normally fatal to a major component.

Speaking of injectors specifically... An injector that is subjected to exteme temperatures at maximum utilization (say 90% D/C or above) is more likely to fail than one that is only working at 75-80%. It doesn't have to be a total failure either. If the motor is tuned perfectly to an injector that is working at 90% and fails to deliver consistently that cylinder will go lean.

Temps that are already high can go through the roof in seconds. Murphy's Law states that will happen when the driver has his concentration "on hitting his line", passing the car he is overtaking, keeping his eye on the flagman and trying to "block" the car behind him.

Now if we were all Michael Schumacher, Dale Earnhardt, Ron Fellows or Boris Said, no problem. The problem is that a lot of people that track their cars only get to the track 3 - 4 times a year, some only once or twice.

The lean condition is not noticed by the computer since it is looking at a 'balanced' output of all cylinders (if at all). The driver is more concerned about the "immediate" needs around him and the rising temps are ignored for the 20-30 maybe even 45 seconds that it takes to get to a portion of the track where he can check his gauges.

In that 45 seconds, oil temps that were already 260 have spiked to 310, oil pressure has dropped to 15psi and goes to 2psi as he enters the last hard left sweeper onto the main straight. (3rd gear 5400rpm under constant gradual acceleration that must be maintained or the car will spin) If a spun bearing is all that happens the driver is lucky. If the motor fails the driver may see some hospital time and worst case, just might not be here tomorrow.

The difference between a #24 and a #30 injector. Is it absolutely necessary? No, but it's damn cheap insurance.

Will it happen to a driver that is as dedicated to his sport as you and Ski and Corky are to yours? Probably not due to the high level of maintainence, dedication and compulsiveness that you put into your setups.

It is a lot more likely to happen to the average guy that just wants to take his driver out to the track and see what it's all about. The guy that went with the #24, had his car tuned right, had it to the drag strip half a dozen times and was amazed at its performance.

Sorry to be so long winded. In some areas I might even have skipped around and my apologies if I did. In case you can't tell, I am as dedicated to my sport as you guys are to yours.

I will also extend an offer to go along for a ride. I'm planning on attending a two day event at BeaveRun in western PA the 4th & 5th of September. I'm not sure where you and Jesse are located but I would be happy to take you out onto the track for a couple of 20-30 minute sessions.

 

Beaver Run? Awsome offer!!!!!
That is about 30miles from pgh.
What is the event? just curious.

 

It is a NASA Ohio-Indiana HPDE, Double Sprint, Three Hour Enduro, Time Trial. I'll be in the HPDE 3 group. For those not familar with it, the URL for BeaveRun is http://www.beaverun.com/ For more information about NASA you can go to http://www.racenasa.com/

 

Switching to sequential injection is not going to solve all of your problems by itself. You're bound to get a few more HP out of the switch, but at this point I don't think its batch mode holding you back. I'm making 405RWHP and 430RWTQ in batch mode on the FAST system.

Ron

 

My apologies to everyone for my part in it.

As for the sequential injection mode, I can't say for certain. I had a bad tune before I went to the DFI. I had a MASSIVE slump in TQ and a significant one in HP between 2500 and 2800 (just about mirroring where your TQ flattens out. My HP curve from 3000-6000 wasn't consistent.

Frustrated, I decided to have John do the entire setup at once. I lost the slump, my TQ and HP curves are smooth and I was able to pick up 35 peak HP more. Much more important to me was that the usable power curve (TQ and HP from about 3200-5500rpm) broadened significantly.

How much of it was tuning and how much was sequential mode control is hard to say.

 

Thanks guys. I am going to try and get more air into the engine and more air out. Other than that, I am just going to drive and enjoy the car for the rest of the season and pay off some of these bills
Maybe over the winter I might try experimenting with different cams and making sure my rings are ok.

 

Can anyone explain why an injector would be more likely to fail at high duty cycle? isn't it just open or closed at the same rate as rpm (or at least based on that) so how does it make a difference if it's open or closed longer, it is still opening/closing the same number of times...and wouldn't the fact that fuel is flowing through it longer at high duty cyles actually keep it cooler? or am i thinking about this all wrong?

sorry to hijack, but i am finding this discussion interesting as i slowly decide what i want to do with my car...

 

konroh,

I am yet to see any evidence or talk to guys at the strip that tax their cars to the hilt, and have someone tell me they locked up a set of injectors....so I think its more myth than occurance. I recall a guy from the TGO stating that he runs his injectors on a testbench at 100% DC and they chatter and heat up. He never did respond back to me when I asked how much fuel he was sending through them, and if he maybe thought that was the reason for all the noise and heat.

Their are comments in this thread that just are not correct. Like moving to sequential possibly making more hp. Sequential gains you pulse width, but if the car is already getting adequate fuel for the incoming air, then its NOT going to make more power.

I think people fail to see the basics of these systems. You have X amount of air, and need Y amount of fuel to reach a certain AFR to get MAX hp. If the 24# injectors are giving you that Y amount of fuel, adding bigger injectors or moving to sequential injection is NOT going to give you more power. If that were the case we would all run the 100# injectors and be making 1000HP.

His tuners are NOT telling him he's lean and the injectors can't supply enough fuel, so the fuel is there to make the power.

Jerkey, you have the right idea - increase the airflow in and out and you will make more power. Plain and simple.

add in: I would however like to clarify the fact that there is a VERY VERY slim chance that sequential injection might be more efficient, due to its firing sequence, HOWEVER, I think the way people are talking about the sequential here has nothing to do with the "efficiency" and more to do with getting more fuel for him. And that is just plain inaccurate and will gain him nothing. Furthermore the gains in efficiency are probably on the scale of <10hp probably more around <5hp. In otherwords incoming clowd cover could pick you up as much at a track.

 

ski_dwn_it, You should move up here to Connecticut so you can tune my car for me No but for real you should.....It needs some serious tuning....My shop wants me to get rid of the FMU from ATI Procharger and use 42lbs injectors( i have stock now)....What do you think??? Plus they never done an LT1 Edit before...the just got the necessary stuff and are messing around wth a workers 1994 vette.....

From the looks of this post 42lbs looks like a bad idea?

 

I would like to move away from the rain, like the driest desert I can find.

i do not have all the specifics of your setup, but I tuned last runner a SC car the guy consulted with me on through the buildup. It was a 355, running 24# inejectors with a FMU. We dialed the car in within an afternoon of tuning the guy was tickled pink with the results and I could not wait to get out of the car, don't mind laying a patch of rubber when i am driving, but not being a passenger.

The guy went to the track and ran some nice 11 sec passes that following weekend, on some 60' that could use some more tire and would greatly increase his ETs. I can't recall the specifics of his times, but I recall us talking about the huge improvements tires would have made. He was VERY impressed with the difference and not being a big drag racer, he never really persued the hook as far as I know.

 

High duty cycles equal longer injector "open time" or duration of time open. The longer an injector is open the hotter injector windings become due to increased time W/ electrical current applied, possibly leading to failure. So the direct answer is fuel injectors can fail due to overheated electrical windings. Increased fuel flow could possibly offset some of the overheating, but it is my opinion that electrical coil overheating is usually very intense and localized.

Most devices are engineered W/ a safety factor, when Bosch rates an injector @ 80% recommended duty cycle to an OEM (GM Ford Etc) Bosch knows full well the injector will run fine to say 85 - 90%, but Bosch can't afford to lose OEM sales due to failed Bosch injectors causing warranty claims over at GM.

Same theory I posted earlier, if an established business makes broad statements, advising clients to use fuel injectors at 95%+ duty cycles, they are walking a fine line with their reputation. If they are making a living out of said business, they will think twice about what they state publicly, especially if the result could be a lean-out fuel condition.

A more responsible position would be to ask the customer to call for specifics, get a feel for the customer and proceed with specific advice accordingly. It appears that is exactly what TPIS has done in the ad posted above.

I don’t doubt some guys are making it work, it would be logical that drag racing would keep the injector at max duty cycle for a very short period of time, before it was allowed to cool. Also a dedicated drag race vehicle would be subjected to minimal time on the street seeing relatively few miles total at max duty cycle thus extending injector life.

BTW, I wanted to add this link to a good cutaway picture of a fuel injector...
http://www.witchhunter.com/injectcut1.htm