hey dudes! i've got a 94 gt, dart block 347, afr 225 heads, trick flow r intake with 90mm tb opening with a 90mm tb, vortech ys--not ysi, front mount intercooler, 75 tooth crank pulley and 28 tooth blower pulley, fast xfi. with this combo it only made 475hp on a dyno with eddie current pushing 15pds of boost. in good air datalog shows 18-20 pds and has run 10.3 at 134. i've seen other people with less stuff run faster and make more power. what's up?any help pleezzz!!!
not enough hp
- Thread starter shoua50
- Start date
-
Sponsors (?)
When you are going that fast there are alot of variables , what tranny are you running , what stall if its an automatic ? What tires ? Whats the weight of the car ? whats your 60ft and 8th mile times and MPH ?
lentech strip terminator aod trans. foward manual valvebody with transbrake. 3200 stall. 373 rear gear 4500 rpm launch with brake and two step. 1.53 60's, 6.59 1/8 @107mph. 325-50-15 m/t drag radials. vehicle weight with me in it is 3683. running 12-16 degrees of timing on pump gas 93. any more then it pings. air/fuel is 10.5-11.0.
car is a pig , loose some weight somehow , what are the cam specs ? timing is low and air/fuel is WAY FAT , I have seen a stock block 331 with trickflow topend kit with X303 with a D1 procharger make more power on 11lbs of boost with 18 degrees of timing and 11.3-11.5 air/fuel
your eighth mile time is slow especially for that 60ft but your MPH is high for that ET , same with your quartermile , you sure the track was measured right LOL ........
your eighth mile time is slow especially for that 60ft but your MPH is high for that ET , same with your quartermile , you sure the track was measured right LOL ........
can't remember cam specs but lift is 608 on both sides, i'll have to check the cam card. run was made at memphis motorsports park in memphis TN last april. memphis motorsports park is up for sale and going to be closed this year unless someone buys it. THAT SUCKS!!!!! anyway next closest track is holly springs dragstrip in MS, it's also an NHRA certified 1/8 mile track. i guess i'll try leaning on it and play with the timing.
TrueBlue95GT
Member
Is it possible that you're blowing out the spark? What's the gap like? Are you running a cam with overlap?
BlackVert
15 Year Member
i'd check the plug gaps and get multi-spark setup like a MSD or something similar
do you have a wideband? What is the A/F ratio?
do you have a wideband? What is the A/F ratio?
BlackVert
15 Year Member
hmmm, sounds like you have the spark issue nailed. 
you need to get your cam specs. if there is overlap, then boost (aka power) is going out with the exhaust during the overlap period.
from where did it come? was it designed for a naturally aspirated engine?
you need to get your cam specs. if there is overlap, then boost (aka power) is going out with the exhaust during the overlap period.
from where did it come? was it designed for a naturally aspirated engine?
TrueBlue95GT
Member
On top of the loosing air through the exhaust thing, you're engine doesn't know where that air is going and it dumps too much fuel into the engine for the amount of air actually in the combustion chamber. This creates a pretty rich condition that the computer might not be able to overcompensate for.
BlackVert
15 Year Member
TrueBlue, i'm not sure i agree with your statement. the only time the computer would actually give too much fuel would be when the MAF reports that more air is coming in than is actually coming in.
that said, what is more likely to happen is that the oxygen in the unburned air/fuel mixture going out with the exhaust would cause the O2 sensors to report lean to the computer, which would eventually cause the computer to try to richen the mixture, even though there is actually the right amount of fuel for the air.
is the above scenario what you were referring to TrueBlue?
then again, that would only happen when the computer is in closed loop, and it is not in closed loop at WOT, so .... yeah
that said, what is more likely to happen is that the oxygen in the unburned air/fuel mixture going out with the exhaust would cause the O2 sensors to report lean to the computer, which would eventually cause the computer to try to richen the mixture, even though there is actually the right amount of fuel for the air.
is the above scenario what you were referring to TrueBlue?
then again, that would only happen when the computer is in closed loop, and it is not in closed loop at WOT, so .... yeah
TrueBlue95GT
Member
Well essentially, the air entering the exhaust is essentially the opposite of a vacuum leak right? The MAF thinks that K is entering the combustion chamber and X is escaping through the exhaust before the combustion cycle, so therefore K-X is actually burning for a fuel amount calculated for K. Am I off on this thought? Just kind of thinking outside of the box. If this is true, it would affect WOT, because when not in boost, the N/A overlap would not affect the O2 sensors, but at WOT the O2s would be disregarded and the computer would never know that there is actually a rich condition. Maybe I'm just 
BlackVert
15 Year Member
i think it is just the opposite .... here's the deal ...
usually the computer starts the injector before the intake valve opens. so what enters the chamber is going to be a mixture of fuel and air, not just air.
since the fuel is mixed in with the air, don't you think that unburned fuel is also going out with the exhaust, not just air?
now consider this ... in it's stock configuration, the computer will spray most of the fuel on the back of the intake valve before it opens, so when the valve opens, the mixture will be richer with fuel right when the valve opens and leaner later.
now the overlap period (when what is coming from the intake gets pushed out the exhaust) is right after the intake valve opens. so what is pushed out the exhaust during the overlap period will probably have alot of fuel in it, leaving what ends up in the cylinder with actually LESS fuel than it should have.
follow me?
there is a table called the injector timing table which is used to control when the injector pulse happens. the values in the table actually specify when (in crank degrees) the injector is supposed to STOP, so to change it, you kind of have to back into it. i have a big old spreadsheet to help do the calculations for it.
usually the computer starts the injector before the intake valve opens. so what enters the chamber is going to be a mixture of fuel and air, not just air.
since the fuel is mixed in with the air, don't you think that unburned fuel is also going out with the exhaust, not just air?
now consider this ... in it's stock configuration, the computer will spray most of the fuel on the back of the intake valve before it opens, so when the valve opens, the mixture will be richer with fuel right when the valve opens and leaner later.
now the overlap period (when what is coming from the intake gets pushed out the exhaust) is right after the intake valve opens. so what is pushed out the exhaust during the overlap period will probably have alot of fuel in it, leaving what ends up in the cylinder with actually LESS fuel than it should have.
follow me?
there is a table called the injector timing table which is used to control when the injector pulse happens. the values in the table actually specify when (in crank degrees) the injector is supposed to STOP, so to change it, you kind of have to back into it. i have a big old spreadsheet to help do the calculations for it.
TrueBlue95GT
Member
Similar threads
- Locked
- Locked
