mattspik

I hope that you guys can help me with my 1994 z28 M6.
I got the car stock with about 125k miles in good running condition. I decided to built it a little my goal was about 360 RWHP so about 410hp at the crank.

I got the block and heads rebuild by local machine shop (DBA s california)
Block got new bearings(main,rod,cam), new piston ring and oil pump (35% more volume)
Stock heads got port and polish, 3 angle valve job, resurfaced shaved performance spring supporting up to .600 lift
I used .026 head gasket to rise compression a little
I got performance camshaft:
intake lift .510 exhaust .520
intakke/exhaust duration is 230/236 110LSA
On top of that I got 52mm tb, Bosch 36p injectors,BBK short tube heades with off road Y pipe and flowmaster, MSD coil and cables, tr5 plugs. All that was tuned by SALMON.
After I installed the engine I was breaking it in I did thermal breakdown, 30-50mph pulls, drove it 150miles new oil etc. Now the car is not as fast as it should be after all the work done to it( it's same fast as stock lt1 with no cat) besides that it does have problem to start cold/warm I have to crank it 2-3 times to start it. I was searching the forums, I found out about knock sensor and module. I disable the Knock sensor so it is not retarding my timing (I used the resistor) I got few gallons of 100 octane racing fuel, still same thing. It still have a lot of power missing, may be it has something to do with hard starts. What you guys think I spend all my money to make it run good and fast, and it feels like maybe 250hp out of 400hp that it should have. Any ideas?

Puck

iTrader: (17)

Mail order tune? Any datalogs?

Without data logging it any guesses would be a shot in the dark.

lifeisgood

iTrader: (4)

what type of injectors?

tricked94camaro

iTrader: (1)

he said bosch 36p injectors.

how is spark and fuel pressure? does it run smooth?

mattspik

I after it starts it runs smooth. I will check fuel pressure tomorrow it should be 42,5 psi at idle with fpr vacuum unplugged that what salmon (mail tune) sad. I got those injectors used for 90$ Is it possible that bad injectors can affect performance so bad?? I was driving the car 5 min ago on wet street and it can't even spin the wheels in 2nd gear going 30mph and wot! I noticed that when I turn the key 2-3 times on ignition on and off then it stars with no problem.

tehmilz

fuel pump? fuel filter?

speed_demon24

iTrader: (6)

From that build sheet I'm guessing your engine builder has no idea what he's doing. You have my condolences.

Oh and throw it on a dyno and post up the chart.

mattspik

I installed new fuel filter. I will try to check fuel pressure
I will install my friend ls1 injectors maybe it will help a little
One more question after somebody tune your pcm do you still have to adjust TB to hold the idle. When i first started my car i had to adjust the screw to keep the engine from dying

mattspik

"From that build sheet I'm guessing your engine builder has no idea what he's doing. You have my condolences.

Oh and throw it on a dyno and post up the chart."

What exactly you have in mind??
For now I am trying to get it run good I am pretty sure that dyno would show less than 200whp

pro94lt

The older I get the more convinced I get on how critical it is to either have a select few proven people or progams port your heads or just leave them alone. I'm not 100% sure thats your problem but do a search of guys with underperforming cars and you'll usually see that they had a local no name shop port their heads (not that you did or your shop did a bad job) Also do you know for sure what pistons they used?

mattspik

Stock they only replaced piston rings, and honed the block. There was no need go over bore. I am pretty sure that it will ne something with fuel, or injectors. Funny think was when I was driving 6th gear at 75mph I hold my foot still but car was accelerating every few minutes and then slowing down. It felt like i would press 50% wot?? I have no idea what could cause it.

RamAir95TA

iTrader: (2)

Datalog, datalog, datalog.

And a +35% high volume oil pump?! Lyk WOAH.

JAKEJR

Seems like a surge condition. I've only had a surge condition once and it was caused by a lean condition. This happened on a carbed engine and going up one size in primary jets cured the condition.

Your surging could be caused by a lean A/F ratio. You'd need to, first, verify what your A/F ratio is. If it turns out to be lean, there are a few different ways to correct it.

Jake

mattspik

Thanks Jake it sounds very possible. I will check fuel pressure and injectors tomorrow. How do I check a/f ratio with out wideband??

mattspik

Ok I went to my friend mechanic shop to borrow fuel pressure gauge (snap on
This is what I got
43psi@ idle fuel pressure regulator vacuum was connected
50psi@ idle fuel pressure regulator vacuum was disconnected
when i connected the fpr vacuum and open tb pressure rised mabe 3-5 psi up and went down.
Is this how good or not ??

RamAir95TA

iTrader: (2)

Your fuel pressure is just fine.

PS...has anyone mentioned that you need to Datalog?

There is no other accurate way to monitor AFR without a wideband.

chavez885

iTrader: (12)

Sounds like a **** tune, time to buy a wideband or go to a dyno.

hitmanws6

iTrader: (20)

Your tune is probably off. Thats a decent cam, could be better but not the worst. Your exhaust is also choking that motor. You are probably giving up 40-50 easily by not running LTs and running stock cats and a flowmaster.

my1994z28

iTrader: (3)

I would install some lts and get a dyno tune..My buddy was running BBK shorties,it ran ok,but after I installed the Pacesetter lts it was night and day difference..In a good way

marc97taws6

iTrader: (6)

Datalog! Broken record

This build seems to be all sorts of fail. What is the damage to your wallet?