TBIThrottle Body Injection discussion and questions. L03/CFI tech and other performance enhancements.
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Roller lifters, roller cam, headers, full exhaust and a tune... 200hp?
I can't afford new heads and the machining involved because I'm going to college next year =(
A lot of people bash LO3's, but honestly, I think they've failed to see the potential one has. GM screwed the motor at the factory: small heads, small cam, restrictive intake and air flow, and restrictive exhaust. They did this to make people shell out thousands more and buy their Z28 for performance.
All you really need to make Z28 performance in an RS is heads, headers, full exhaust, a better cam, upgraded lifters, and a good tune. An open element air filter also helps to get more air into the motor. I've met several people with RS Camaro's with these mods matching 350 Iroc's move for move. I've seen some kick a$$ LO3's with "the usual go fast mods" that I just named.
Now it all depends on what you want to have, street drivability performance, or race car oriented performance.
I have a buddy with an LO3 1991 RS, 5M, he's got 4K into the motor, and he's running mid 14's. That car hauls. Heads and cam are the biggest HP gains, and the priciest, but you can build a 305 TBI to smoosh L98's and LT1's with a pretty laid back budget.
I'm not trying to knock on 350's, I like them, but why swap a perfectly good 305 that can easily be modded to embarrass a 350 for the same amount of money?
go rent a fuel pressure gauge, and get a t fitting to put on your fuel feed line to see if you are getting at least 12 psi pressure under wide open throttle fueling at a high load.
if its not that, it has to be timing. take some pictures of the distributer so we can see if its the correct style distributer for the car. also some pictures of the throttle body with the lid off to see if its the correct tb and the injectors are correct.
off the top of my head im thinking the backyard mechanic may have done a better job that you had thought swapping to carb'd. maybe he put a non electronically controlled distributor in it. i'd set the timing to about 4 to 6 * btdc advanced to if yolu havent.
i had an old l03 that couldnt even go up a hill under 3k rpms when set to 0* btdc but when advanced to 10* it ran like a raped ape. my reason was a worn timing chain/gears/cam drive gear or dizzy gear but you may have something similar bothering yours.
A TIMING light can also be rented from your autoparts store which would also help a lot and it would be free...... you could check to see if it looks like its advanced 25-30* or so when reved up with the connector hooked up and check and reset your base to 4 to 6* btdc. Hopefully this may help as there is a whole lot of misinformation in this thread. if your problem has already been diagnosed or you need clearer details on how to do any on the following pm me and i can break it down a little easier.
Last edited by flaming-ford; 12-16-2008 at 09:12 AM.
i agree with thomas, there's some serious work involved to get the L03 to put out >300hp. anyways, it seems the problem here is that your (Aaron's) engine is not even up to the stock specifications, so tuning & modding advices are misplaced here. nevertheless, the only thing to actually get it fixed is to start working on that dang thing c'mon!
as said you would really need to go into details about which EXACT parts you replaced when you converted it back to TBI! there are numerous things one could oversee when doing this.
if you have no troublecodes at all, as somebody else already stated start, with basic checks like fuel pressure and timing, if the throttle blades are really going to WOT, etc.
btw, what kind of carb was on it? computer-controlled like the quadrajet or a 'real' carb, mechanical one like a holley?
hth, ownor
Wow, thats way off. Ive done all those mods, I know the results, lol. The exhaust will not give you 30hp. Maybe 15 like I said. Trust me, the stock exhaust does suck, but the motor makes such low hp that the exhaust doesent hold it back THAT much.
Headers + Exhaust + Chip Tuning gave me 35 RWHP over what the stock L03 Manual transmission in another post here dyno'd.
My 305 was backed to an automatic though and was an internally stock engine, headers, dual 2 1/2" exhaust, high flow cats, and low-restriction dynomax RV type mufflers. This engine made over 280 RWTQ when tested at a lesser engine speed. Notice how the pull started at 3,500, way higher than the stock cams peak torque over 2,400 rpm.
My 305 was backed to an automatic though and was an internally stock engine, headers, dual 2 1/2" exhaust, high flow cats, and low-restriction dynomax RV type mufflers. This engine made over 280 RWTQ when tested at a lesser engine speed. Notice how the pull started at 3,500, way higher than the stock cams peak torque over 2,400 rpm.
Every dyno will give slightly different results. And check my dyno sheet. I gained VERY little with a dyno tune, upped fuel pressure [wasent running rich] and headers + exhaust.
So I dont see how you did it, maybe you should open your own dyno shop. Because the place I took it too even said that we werent going to get any more out of it then what we did.
Im taking my car to the same dyno again in a week or 2, so I can try to get my tune a little better with my new mods [XFI268 cam and 113 heads], I doubt ill get more then 230whp.
Every dyno will give slightly different results. And check my dyno sheet. I gained VERY little with a dyno tune, upped fuel pressure [wasent running rich] and headers + exhaust.
So I dont see how you did it, maybe you should open your own dyno shop. Because the place I took it too even said that we werent going to get any more out of it then what we did.
Im taking my car to the same dyno again in a week or 2, so I can try to get my tune a little better with my new mods [XFI268 cam and 113 heads], I doubt ill get more then 230whp.
I know, but I gained 25 RWTQ and 15 RWHP on a STOCK L03 by prom tuning. The truck calibrations ran VERY rich in PE and had very little timing. The cars have a very lame advance curve too.
I made 210 RWHP with stock 14022601 heads, on a stock flattop piston 305, with a 204/214 @ .050" cam, through tri-y headers, duals, with prom tuning of course. Basically stabbed a "RV" cam in my stock 1983 Van engine, then dropped a TBI on it and tuned it. When that engine went, I put in a stock rebuild of a L03 truck engine.
I ran a 312 CID BUILT engine with a XFI 276 and slightly re-worked ZZ4 casting 113s and made 423 FWHP @ 6,500.
I know, but I gained 25 RWTQ and 15 RWHP on a STOCK L03 by prom tuning. The truck calibrations ran VERY rich in PE and had very little timing. The cars have a very lame advance curve too.
I made 210 RWHP with stock 14022601 heads, on a stock flattop piston 305, with a 204/214 @ .050" cam, through tri-y headers, duals, with prom tuning of course. Basically stabbed a "RV" cam in my stock 1983 Van engine, then dropped a TBI on it and tuned it. When that engine went, I put in a stock rebuild of a L03 truck engine.
Then you really need to open your own dyno shop. I cant get near those results. Even with my tune now, im having a REALLL hard time getting it to run smoothly, let alone get amazing results. Like I said, im going to the dyno in a week or 2, and I doubt ill see over 220whp.
Then you really need to open your own dyno shop. I cant get near those results. Even with my tune now, im having a REALLL hard time getting it to run smoothly, let alone get amazing results. Like I said, im going to the dyno in a week or 2, and I doubt ill see over 220whp.
One thing that you have to remember is that you need to change both spark and fuel at the same time. Also, the base timing needs to be advanced or retarded (depending on what the engine likes) up to almost 30 degrees. And this is something I have a good deal of experience in. I joined FSAE for the specific reason to learn how to tune. We spent two weeks dialing in our base timing alone. Needed 394.5 degrees of advance and another 18-37 degrees of spark advance. Thats in addition to increasing the IJPW by almost 15% per cell on the fuel map. We're making almost 100hp out of an otherwise stock 600cc motor.
Then you really need to open your own dyno shop. I cant get near those results. Even with my tune now, im having a REALLL hard time getting it to run smoothly, let alone get amazing results. Like I said, im going to the dyno in a week or 2, and I doubt ill see over 220whp.
There is really nothing to it, give the engine what it wants fuel and timing wise. But then again, my current TPI engine hasn't even had a scanner hooked to it. I tuned it all seat of the pants, fuel, ae, and timing, since the ALDL output in my 7730 ECM died.
There is really nothing to it, give the engine what it wants fuel and timing wise. But then again, my current TPI engine hasn't even had a scanner hooked to it. I tuned it all seat of the pants, fuel, ae, and timing, since the ALDL output in my 7730 ECM died.
Could you explain to me what the VE tables are? Are they similar to the fuel map on a Motec?
That spark table looks like it should, maybe a little more tuning in the 70% and higher area is requiered, not sure though.
I am not familar with the Motec stuff, but the factory GM VE tables are used in conjunction with the base pulse width (based off of injector size and engine displacement) and some other adders/multipliers to calculate the actual pulsewidth to the injectors. The VE table will roughly indicate the true VE of the engine. The table is based off of RPM and MAP. The numbers in the table are then interpolated for fuel delivery lookup.
Timing table may seem a little weak off-idle and under heavy loads at light throttle, but this helps de-sensitize the throttle response and helps fuel mileage ever so slightly. I have a chip that lets the 350 burn the tires taking off at anything over about 1/3 throttle. Way too much for a rainy day, or trying to creep through school zones.
Your tables are like, ridiculously smooth.
Thats what the motor likes? I did VE learns and after 8 or 9 of those, I checked it out in tunerpro and manually smoothed it out a little bit. Guess im going to have to go make it totally smooth.
My SA tables right now were the stock ones, but I recently tried the LG4 SA tables that come with the EBL. Really messes up the idle and it stalls a lot more when i come to a stop, but it dident really give me any knock even at WOT. Dident really notice much of a difference performance wise with it though.
[The LG4 SA table adds a lot of SA]
I think ill start a thread in the tuning section, if you wouldent mind taking a look at it [should be up in the next 15-20min]. Ill post pics of all my tables that have been modified.
I am not familar with the Motec stuff, but the factory GM VE tables are used in conjunction with the base pulse width (based off of injector size and engine displacement) and some other adders/multipliers to calculate the actual pulsewidth to the injectors. The VE table will roughly indicate the true VE of the engine. The table is based off of RPM and MAP. The numbers in the table are then interpolated for fuel delivery lookup.
Timing table may seem a little weak off-idle and under heavy loads at light throttle, but this helps de-sensitize the throttle response and helps fuel mileage ever so slightly. I have a chip that lets the 350 burn the tires taking off at anything over about 1/3 throttle. Way too much for a rainy day, or trying to creep through school zones.
So I have to tell the ECU what injectors I'm using and the engine displacement so it can compute the VE table. From there I tune each cell individually for desired results. Correct?
And that makes sense about the spark table. Didn't know it would affect throttle response.
i agree with thomas, there's some serious work involved to get the L03 to put out >300hp. anyways, it seems the problem here is that your (Aaron's) engine is not even up to the stock specifications, so tuning & modding advices are misplaced here. nevertheless, the only thing to actually get it fixed is to start working on that dang thing c'mon!
as said you would really need to go into details about which EXACT parts you replaced when you converted it back to TBI! there are numerous things one could oversee when doing this.
if you have no troublecodes at all, as somebody else already stated start, with basic checks like fuel pressure and timing, if the throttle blades are really going to WOT, etc.
btw, what kind of carb was on it? computer-controlled like the quadrajet or a 'real' carb, mechanical one like a holley?
hth, ownor
Yeah, I'll check it out and let everyone know. The car had a 650 CFM Edelbrock four barrel carbureator on it. Sold it for $300.
Could you explain to me what the VE tables are? Are they similar to the fuel map on a Motec?
That spark table looks like it should, maybe a little more tuning in the 70% and higher area is requiered, not sure though.
GOOD NEWS YOU GUYS!!!
I lost my job. Misread the schedule and didn't show up for work yesterday. My boss called me four hours after my shift was supposed to start, and told me I didn't have a job. Haha... Try finding another good, well paying job with the market like this!
So, I guess the poor Camaro is going to have that oversized TB on it for longer than I expected (I think that's the problem, it makes a lot of sense).
c'mon!
