SERIOUS problem: tuning gurus needed.

[disco stu]

FWIW this is the rail I used on my car with tons of 14x MPH passes on it.

 

[Otto J]

If its got an original High Mileage inj harness,get rid of it and I prefer the injectors o be hotwired also

 

[disco stu]

If its got an original High Mileage inj harness,get rid of it and I prefer the injectors o be hotwired also

I agree.

 

[bison]

I agree, I'm kicking myself for not doing so. I thought it looked good enough on the street and went for a full pass. I was wrong.

Running retarded timing will raise EGT's but lower cylinder temps and pressures since more of the heat is getting let into the exhaust.

Its hard to say whats going on in the cylinder as the egt's start to climb. Id re-flow at 75psi and analyze that data. Maybe the valve is getting hurt before the cylinder is getting hot or maybe a bad ring seal on that cylinder letting some oil in? Oil in the cylinder will raise the temps.

 

[Otto J]

After installing an inj hotwire harness from Caspers,everytime i have had to retune as the car runs rich in all areas

 

[disco stu]

Its hard to say whats going on in the cylinder as the egt's start to climb. Id re-flow at 75psi and analyze that data. Maybe the valve is getting hurt before the cylinder is getting hot or maybe a bad ring seal on that cylinder letting some oil in? Oil in the cylinder will raise the temps.

True, but the last tear down revealed that the intake, runners and bores were spic and span. 5% leakdown as well. Everthing seems tight as far as cylinder sealing is concerned.

 

[bison]

True, but the last tear down revealed that the intake, runners and bores were spic and span. 5% leakdown as well. Everthing seems tight as far as cylinder sealing is concerned.

You stated you lost 50 psi on that hole

 

[disco stu]

You stated you lost 50 psi on that hole

Well, I meant that the combustion chambers elsewhere and otherwise looked clean burning engine. No oil, carbon or any sign of cantamionation anywhere. 5% or less leakdown everywhere before problem. I did loose 50 psi on that hole. When it happened the first time it hurt the hear between the valveseats and burned a little aluminum off the piston edge.

I don't know what it looks like now, but I am willing to bet the same thing or something similiar happened.

 

[disco stu]

You stated you lost 50 psi on that hole

Well, I meant that the combustion chambers elsewhere and otherwise looked clean burning engine. No oil, carbon or any sign of contamination anywhere. 5% or less leakdown everywhere before problem. I did loose 50 psi on that hole. When it happened the first time it hurt the hear between the valveseats and burned a little aluminum off the piston edge.

I don't know what it looks like now, but I am willing to bet the same thing or something similiar happened.

 

[Blazer406]

1st thing you need to make sure your fuel pumps are flowing 1.5 gal /per minute @75 psi, not 45 psi. If not go to a big external or put a kenne bell boost a pump on it and reflow.

We just went thru this... battery hooked up to the battery charger... we got 1:23 sec for 1 gal at a little over 70 psi..... on each Walbro 255 LPH pump. Together... we get about 47 sec to fill one gal.

.......On my car i am adding 20% more fuel to Cyl #1 to keep the egt's within 50 degrees of each other

Holy smokes!

What intake?

 

[norbs]

Hogan Sheet metal, I don;t know how to explain it but that cyl is really lean on my car. I swapped injectors from another cyl, same thing.

If you are flowing 1 gal in 47 seconds this comes to 1.28g/min. x 60 min = 77 gph.

77 gph x 6.2 lbs per gallon= 477 lbs/hr


If you had 83's at 100% duty cycle that pump setup won't be enough.........for example.498 lbs/hr

 

[John Wilde]

After installing an inj hotwire harness from Caspers,everytime i have had to retune as the car runs rich in all areas

That is interesting and scary at the same time!

 

[norbs]

I would suspect that the head was damaged the 1st time and your repair is still in the weak spot and failed again. You may have to replace the head, I'm thinking

 

[Otto J]

That is interesting and scary at the same time!

You can't trust 21 year old wiring.

 

[Louie L.]

I would certainly look at the Inj harness and pumps but.......

Cyl 1,5 an 6 on my car were like that when i used a stock intake. It would destroy 5 and show lean on 1 and 6. I started adding fuel to those 3, up to 5% on #5 and it stayed alive.

 

[Blazer406]

Hogan Sheet metal, I don;t know how to explain it but that cyl is really lean on my car. I swapped injectors from another cyl, same thing.

If you are flowing 1 gal in 47 seconds this comes to 1.28g/min. x 60 min = 77 gph.

77 gph x 6.2 lbs per gallon= 477 lbs/hr


If you had 83's at 100% duty cycle that pump setup won't be enough.........for example.498 lbs/hr

This was our results with twin in tank Walbro F20000169's....which are supposed to be equivalent to the 340's...... however they seem to be having a widespread issue with cartain dates of manufacture.......

Anyway... we are also running a volt booster now.... and alky..... so I think we are good to mid 9's anyway...

I'd be curious what yours flowed....

FWIW....we are installing a Weldon 2015 before next track outing....

 

[TURBO 6]

Post a pic of the plug if you can.

 

[KL Mallender]

I'm sure that your tank is vented properly for that much fuel "Removal" during operation

Kevin.

 

[disco stu]

I don't have my camera right now, the plug is torched. Electrode, ground, and ceramic. It's nuked.

Tank is vented.

 

[lazaris]

I think theres something to that cylinder shown while on the 2 step. I dont think that its a coincidence that particular cyl is low during the 2 step operation. Also the sudden sharp rise in EGT is out of no where. Where you always running alcohol even when you had the first failure? Where are you injecting the alcohol?