Im kinda frustrated and need to know where to start. My 86 Z-28 is not nearly as fast as i think it should be...14.4 in the quarter. Monster bottom end torque, but feels like its sluggish and looses power through the RPS's...Any suggestions? Could it be because it was originally a 305 and maybe the computer is doing somthing? UGHH im frustrated, but dont have the cash to take to a mechanic. Any help would be greatly appreciated.

Heres whats done: ZZ4 crate 350, ported & polished TPI, oversized injectors, Fairbanks 700-R4 race trans, BBK/Edlebrock throttle body, SLP CAI, SLP exhaust and headers.

 

That's an awfully big question. And you provide such little detail.

First start off with the entire timeslip. 14.4 doesn't mean a damn thing.

Second, things like converter size and stall speed, rear end gearing... etc.

Then we'll get the details like the ECM and chip swap, injector size, fuel pressure, the list goes on.

You do know that TPI setup won't make power past 5000RPM in stock trim right?

 

okey doke couple things
first post all the times you have 60 foot, quarter etc
second i dont believe the 305 and 350 chips are the same that could definitly kill your performance.

Also what gears do you have that might be killing you too? With that combo and some 3.73's you should be nicely down into the 13's with traction

 

Would you be willing to swap to an LT1 manifold?

My last car was probably the same as what you're dealing with. New 350 bottom end with TPI up top. 1.80 60 foots and a solid 14.40 timeslip. Huge torque, no HP past 5000rpm. A better intake, gearing, and torque converter selection can REALLY wake things up like these guys are saying.

 

HMMMM, Like the others said, more info is needed,60 ft times and MPH would give a lot better indication of whats going on.I have a similar car, 86 Z ,ZZ4 motor,19lb injectors,3:73...(too much gear fot a TPI),2500 converter,and a DIY chip.With 275/60/15 street tires best I have run is a 13.70@102.7..going through in 4th, this is on a 2.10 60 ft,leaving @ idle and flooring it aprox 30 ft out.

Good luck

Greg

 

fuel pump??
You need a gage to check on a run for pressure drops.
Timing can also affect that.

 

MAf car right? Did you have the MAF calibrated for the larger injectors? If not, you are going to have problems, and I would say it is too small for that crate anyway.

 

Cant find my timeslips, and havent recalibrated the MAF. How do you recalibrate? Or who would be able to do that for me.

Im actually thinking about selling the car now...I have to many projects and want to buy a house. And work wayyy too much!

 

The chip should help more than anything. Oversized injectors are getting the same pulsewidth as the old ones. The car is probably way rich.

Also, 3.73s would be great behind a stall.

 

Yeah, MAF cars are very sensitive to injector size. If you switched from stock 19lb units (on a 305 TPI they used 19s- 350 TPIs had larger 22lb units) to 24s or larger you'll be running fat. Chip programming is the only way to really fix this right. A custom chip would probably help quite a bit with your combo.

 

GM MAF sensors and injectors are not calibrated like Fords are. The stock MAF sensor is fine.

The problem has to be in the tuning.

 

Basically you threw a replacement 350 in there did minor mods (porting) and picked up .5 in the 1/4 from what a stock motor would have done. I don't see that there is that big of a problem here. Now if you had done all the work I have to my car and still run 13.7 @ 100.3 mph... that'd be a different story. The problem you have is your headflow and intake flow characteristics for going faster. You're not gonna see a whole lot of gain until you get a nice .500 lift ~220* duration cam in that motor. I bet ya that cam,headers, reprogramming, gears will get you to the 13's. It got me there.

 

Been a while since I have owned a TPI car