1/4 mile tuning help

[thbjcb]

Went to the track for the first time in 25 years. Car ran a 12.5@117.4 mph. Goal was to get into the 11’s which it should have done but my 60’ are terrible at 2.5. For some reason when I try to build boost at the line the RPM will not go any higher than 2600 even with my foot to the floor for a few seconds. Once I hit second gear it the thing takes off.
Mods are as follows 3” DP, alky, 60 lb inj, home P&P heads with bigger valves, old school 208/208 cam, 62-66 turbo, Dave Husek trans, 9” Full Throttle TQ converter, stock rear end, 26” tall tires, SST drivers replacement header (no gasket) and crossover pipe

Things I am going to look at
Exhaust leak on the drivers side from the old felpro gasket, idle FP, recheck turbo waste gate alignment


Looking for any other recommendations.

 

[TexasT]

I think it is obvious but maybe not. That 2.5 60' ain't gonna cut it even with the freight train top end. sounds like the converter is stalling at 2600 rpm. Not sure how you have your alcohol set up but you could be "drowning" it . Are you logging these passes? Just getting the 60' into the 2.0 range will get you an 11sec slip but with the 117 mph there is a LOT more in it.

You need some traction. You don't say it is spinning but if it isn't that is quite a bog.

 

[thbjcb]

Tires are not spinning. Boost sits at 4 psi until about 25 mph then rises. Alky doesn’t start until about 7psi. I attached images of the data log so hopefully you can see what I am talking about.

 

[Sweet6]

Usually a bog is from an exhaust leak. But make sure no leaks then look at fueling, But usually Erics chips are spot on.

 

[mblum]

Looking at your trap speed and the terrible turbo lag on your 12.5 run, if you get it sorted out you probably have enough for a low 11 sec run without trying hard, but you need to get that turbo lag figured out. I'd have to assume this car on the street is very slow to respond to boost by looking at the screen shots. How responsive is it on the street say rolling into the throttle in 1st gear at 15 MPH? It should light up that turbo in no time.

If you have the powerlogger can you post it up? The file itself, so others can open it and look at more than just the screen shots.

As mentioned, you need to check for exhaust leaks pre turbo. That is at the cylinder head to header, closely inspect for cracks on both drivers and passengers side heads, make sure the cross over pipe is sealed up, and the drivers size header to turbo connection. Small leaks after the turbo are not as critical other than smelly exhaust fumes . It doesn't take much of a leak to kill the spool time and responsiveness.

There needs to be ZERO leaks. This is where a smoke machine is super helpful.

I know you listed some mods, but post in your signature all your mods, everything from chip type, MAF, how your controlling boost, basically anything that is not stock/original.

 

[Reggie West]

Ill bet your alky kit is kicking in at as it should at 8 psi and its running rich. Check your instructions for it, there is a way to set up a switch off of the brake so it will stay deactivated when torque braking the car off the line. You should be leaving the line at 10 to 12 psi at least. Once you launch, the car should not get out of boost out all. You should leave the line under full power and you should cross the finish line under full power.

 

[THensley]

He broke the sprag in the converter Id bet a 6 pack of good beer on that.

 

[THensley]

look at the log its flat at 2500 at part throttle, he gets it rolling converter is not working 1-2 shift it goes flat again look at MPH no converter slip, but RPM is high enough for it to pull through

 

[thbjcb]

Data file attached. (Couldn't get to attach using my phone for some reason)

Other mods - Turbo tweak chip 5.7, newer style MAF and translator, Stock style wastegate setup with HD actuator. Brass manual boost controller. I did add a new alternator this spring and the voltage went from 13.1 to 13.9 at idle. Hot wire running from the alternator to the fuel pump. Fuel pump is a Detchworks 300. I tried pulling 10% fuel out in 1st gear on the data file attached but didn't help. It's never been this kind of a dog out of the hole. 25 years ago I pull 2.0 60' on street tires.

 

[thbjcb]

Checked fuel pressure with and without vacuum and the value is the same at 41 psi using my Ken Bell hood mounted fuel pressure gauge. Not sure why that is. Any ideas? How much different should they be with and with and without vacuum ? Would this cause my issues?

 

[THensley]

its 41 because the return line is to small for that pump. It works for some and some it dose not. Yes that is a problem but not your lousy 60 ft problem. I bet a 10 lb boost fuel pressure is around 50

 

[TireFryer]

Sounds like your converter is too tight. Or the turbos too big to spool and “get on the brake”.. basically not enough power to get into boost on the brakes for a leave.

 

[THensley]

Checked fuel pressure with and without vacuum and the value is the same at 41 psi using my Ken Bell hood mounted fuel pressure gauge. Not sure why that is. Any ideas? How much different should they be with and with and without vacuum ? Would this cause my issues?

41 vacuum line on or off is because return line is to small it should be 43 line off line on it should drop to around 35 all cars are different
At 0 boost it should be 43 and rise with every pound of boost 10 psi boost =53 psi fuel pressure.
I truly don't believe that's the problem,
I broke a sprag in the converter and my car went from a 1.75 60 to a 2.5 Do the Google such on broken Sprag you will find you have the same symptoms
That turbo with OE D5 will perform better than that and Fullthrottle would have spec the right converter
Im no trans expert but you might want to call one.

 

[SCOOBY DOO]

I looked at your file.

BLM at idle is 141...you have a pre turbo exhaust leak(s), vacuum leak(s)
You left the line a 2475 RPM's...which is your reason for your poor 60 foot time
02's in high gear were were 756 which is getting lean

Park the car till you get your BLM's sorted out. I have vids on how to change head gaskets if you don't want too.

 

[SCOOBY DOO]

Find out from FT what the stall is for that convertor.

 

[thbjcb]

Took off the passenger side exhaust manifold and the 15 year old gasket is showing signs of leaking all over. Also found the turbo flange to the manifold had some serious leaks as well. Waiting for copper gasket to come for the turbo flange and reinstalling manifold with no gasket using the high temp permatex like I did on the other side with SST replacement header. I will check with FT on the stall.

 

[Chuck Leeper]

Look for fine cracks in the bottom of the bellows...

 

[THensley]

I looked at your file.

BLM at idle is 141...you have a pre turbo exhaust leak(s), vacuum leak(s)
You left the line a 2475 RPM's...which is your reason for your poor 60 foot time
02's in high gear were were 756 which is getting lean

Park the car till you get your BLM's sorted out. I have vids on how to change head gaskets if you don't want too.

Hi BLM at idle fuel pressure is high
Sprag broke
lean at top because fuel pressure is low at boost because he only has 41 lb vacuum line off so at best his fuel pressure is 51 at 10 lb boost and not 53 witch will make 02s lean
with enough power to go through the traps @117 and a 62/66 turbo a D5 will flash higher than 2500
I would like to see a older time slip of this car I'm sure the 60 was not this pitiful

 

[SCOOBY DOO]

Set the fuel pressure to 43 line off. It'll drop to about 38 when you reattach the line. I assume you have the Translator set correctly. Also, I assume that chip is burned for your EXACT combination and you told Eric you were gonna run over 25 PSI of boost. Erics chip has aggressive mode. Just jump the low gear timing 1 degree. Read up on it. It's in his instructions at the bottom. Verify what the stall is for that convertor.