TransAmcoupe98

iTrader: (10)

Guarantee its the injectors...shouldnt be ran the high of a DC

Bradlyj8Z28

iTrader: (4)

Subscribed to see your results!

STREETSLEEPER

iTrader: (6)

A little late but you need new injectors like the post said earlier. When your injector duty cylcles are at 100 percent they are continuously spraying. And that is the physical limitations of the injector. Botttom line the engine will not make **** more untill you listen to the tuner. They can build enigins better than you can shop at summit. You need at least a set of 42's at the minimum. Now when that happens the injector can spray more fuel with each burst and have a break in-between pulses. I maxed out my injectors with a cam and set of headers on a stock bottom end ls1. If you are running out of power the simple fact is those injectors are to small and that cam will not work on that map.You can mod these engine untill you are blue in the face but it simply won't work right untill you get those duty cycles down and re-map for that cam. But you are asking your tuner to ring power out of an imcomplete build. You can't pick and choose the area's you want to mod and the one's you don't. If the tuners says do somthing about it do it and don't ask questions. Hate to come off preachy but it's the truth.My stock cube ls1 put out 400 RWHP and 370 RWTQ with cam and headers. With the heads and all the other mods it made 440/384 ( without nitrous ) on a nitrous tune ( three degrees pulled out via HP tuners instead of the Nitrous controller). If would made a **** ton more power at 28 degrees total timing instead of 25 degrees. Now I did pull out 401/391 on a stock ls1 with a 228 cam, headers,28lb injectors instead of the stock 26 pounders that come stock on the 99 models. My point is you should be making well over 400 with that set up. PERIOD

jthunderz28

Take it to the track, too many variances on Dyno's especially when you Dyno it a year and a 1/2 later.

Trap speed won't lie to you. Dynos just have such a high level of variance when taking into account all the variables that could happen regardless if its the same tuner person.

I was a bit dissapointed with my EPS Cam in terms of the trap speed as well. I dynod 390/365 with a 222/226 cam and after countless passes at the strip, my best trap was 112 mph. For a cam/header car putting down a supposed 390/365 that just seems low.

I will say its daily driving manners are superb and it passes smog here in Cali, once I remove my headers of course.

Hope you figure this out though, I agree you should be putting down better numbers than that.

Dynos can lie but the track never lies.

STREETSLEEPER

iTrader: (6)

The part that gets to me most is the torque numbers on that motor. It should be over 400 I would imagine with those cubic inches at your disposal. Especially with the present camshaft. I would like to know the size of injectors he has at present. I know the cost is a issue but I do think that might free up some torque and HP. They are stupid easy to tune on HP tuners so don't let that hold you up.

LilJayV10

iTrader: (39)

Did anybody actually read that his transmission went out or is everyone just repeating what has already been said earlier in the thread?

ZNix

iTrader: (1)

What converter did you use?

Bumpin' Yota

Nope. No one read that his 3-4 clutch pack was slipping and that the torque converter blew up. Like the bullshit about the injectors being the issue. Weren't helping being at 100% but certainly not the cause of this.

LilJayV10

iTrader: (39)

You are definitely right about them being at 100% isn't helping.

odarabla

iTrader: (1)

There are a few problems I think you need to clear up with your setup before blaming the person that speced your cam.. Just a thought.. Address your issues then redyno. Be sure to post the results along with an i'm sorry letter..

redtan

iTrader: (5)

Help me understand this for a sec. Say that a certain motor makes best power/torque at 12.8 AFR across the board.

What is the difference between stock injectors @ 95% duty producing 12.8AFR vs. bigger injectors @ 80% duty producing the same 12.8AFR?

If the stock injector can deliver enough fuel to get the desired AFR, why would it being at 95% duty make a difference vs. a bigger injector delivering the same amount of fuel but at 80% duty? By that thought process, a humongous set of 142lbs injectors delivering 12.8AFR while at 20% duty will make even more power no?

Bradlyj8Z28

iTrader: (4)

Duty cycle affects the spray pattern which affects the efficiency of the burn.

zacht

iTrader: (18)

im in for results too!

wildcamaro

iTrader: (15)

I am def curious to see the result after the Trans/injector issue is dealt with...should put down over 400+ tq no doubt

Bumpin' Yota

The duty cycle of the injectors is in relation to how long the valve is actually open (roughly). Thus having an injector spray at say 95% duty cycle means that it is essentially spraying enough fuel, as commanded by the ecu, to maintain the commanded AFR. It just so happens to get enough fuel, the injector has to fire continuously for essentially 95% of the time the valve is open. A bigger injector firing the same quantity of fuel can do so more quickly, and earlier in the valve opening, thus more of the sprayed fuel charge actually is pulled into the cylinder rather than the last bits of the 95% duty cycle getting trapped in the intake runner.

This is also why you can have a 120% duty cycle on injectors... ...it's very far from ideal, but it still works.

redtan

iTrader: (5)

Right I get that, but AFR is measured after the fact...so even if some of the fuel from the last bits of the 95% duty cycle is getting trapped in the intake runner, enough fuel is making it into the combustion chamber to create a 12.8AFR.

So small injector is spraying a lot of fuel and some gets leftover in the intake runner like you said, then the rest goes into the combustion chamber to create a 12.8AFR. Bigger injector spraying the same amount of fuel but in a quicker shot that none gets leftover in the intake runner and it all goes into the combustion chamber to create a 12.8AFR.

So in your example, both injectors deliver the same amount of fuel to the chamber (by the 12.8AFR) while one wastes some fuel back into the manifold and the other doesn't.

So we can say that in your example, the only drawback of the smaller injector is waste of fuel because some of it is lost back in the intake manifold. But they both deliver the same amount of fuel and create the same power.

speedtigger

iTrader: (16)

Good fuel atomization is important, but I have never seen any evidence that injector timing, on an intake port injection system, has any measurable effect on WOT engine output. If you have any tests to the contrary, I would be happy to look at it. The idea these fuel injectors are perfectly timed to spray fuel precisely and only when the intake valve is open at all RPMs and all conditions at WOT is highly unlikely. Even if that would be engineered in, it would all likely be lost the minute tuners started changing injectors, fuel pressure, fuel curves etc.

sman

iTrader: (4)

Wow did this thread take off. Been extremely busy and finally had the trans redone and new converter in.

Also picked up a set of GM ASA 42lb injectors.

Going to try and finish getting the spray wired up and the 42lb'ers in this weekend after the Woodward dream cruise. If thats the case possibly get it back to the tuner and make some pulls by next weekend.

Mike454SS

iTrader: (4)

I thought EPS inspected his cams before shipping. Maybe it was an option that I paid for and forgot it was optional...but his inspection report is a lot more detailed than what I can tell from a degree wheel. I still advocate using the degree wheel to know that the timing set is putting the cam where it needs to be...but unless you're running something adjustable, you can't fix anything either.

stinkybutt

I never would have believed that injector timing can make a diference in power. IT DOES. On our dyno we played with a 331 Ford twin turbo. Car made 720rwhp using 91 octane fuel,19*timing and 10lbs boost. AFR 220heads, Comp solid roller. Anyway the car has an Accel DFI set-up. We were just playing with the injector timing, moving it back and forth 5* then 10*. You could hear the engine change @ idle. Then on power pulls it made close to 35ft/lbs @ 4,000rpm diference. We spent a day just toying with this. I never thought that a few degrees in injector timing would make that much change. You think that we are talking miliseconds. BUT we tried several times and plus driving up thru the gears the part throttle was more crisp.
The car is a 65 Comet with a viper 6 speed. and is 3,000lbs.