Got car to the track this weekend- not very impressive times

So took the car up to the track this weekend to try and get it running better. Was running very lean so we ran a couple vent tube extensions- it went to running rich with no other changes.

Opened up the carb and changed the jets. Problem is when we changed the vent tube extensions we didn't get to run it before my nephew (the blow through carb guru) had to leave to get his car. He met us at the track- well we changed out the jets and it was still running rich - even worse than before. Seems like we forgot to tell him it was running rich after the vent tubes so he put in bigger jets. Oops. We then pulled the rear vent tube off and it was a lot better- but it was bogging down on launch. Well we had been wrenching on it for a long time and the A/F was 10-14 thoughout the range (even when bogging down on launch) so we all three took our cars for a 1/4 mile run. My time was a horrid 16.1 @ 92 MPH with a 2.5 60' time. I could only go 1/2 throttle without it bogging down- we changed the jets a little smaller and it was running better on launch but would still go faster at 3/4 throttle than full, but even at 3/4 throttle traction became the limiting factor. I am still on street tires (Eagle GT radials)- I had hoped to get some slicks before the weekend but they fell through on Friday night.

Second run I had a better 60' time- 2.4 and 14.2 @102 MPH but at 500 RPM she was breaking up. This was my first time ever at a drag strip so I was too busy keeping my eyes on the track to look at what the A/F was doing when breaking up.

Third run we had it running even better- full throttle response was OK (not great but better- it was not picking up speed like it should but was not bogging down) on launch- I did another 3/4 throttle launch then mashed it once got rolling- just spun the tires.

Got 2.4 60' again and ended up 14.8 @ 94 MPH - it was breaking up worse and was starting at 5000 RPM- I was looking at the A/F this time and at WOT in second gear I had A/F of 10.X and third gear just after shifting (when it was breaking up at shift point)- I had a 12.X A/F.

I am getting some 28X9X15 slicks today and next weekend hopefully we can spend some more time on getting the jetting right- we did a bunch of other work this time to get ready for track (fix leaky valve covers/put in new temp sending unit/replace a couple intercooler couplers that were a complete PITA).
Getting better- when we started on Saturday morning it was super lean and would die out when you gave it gas. It is now OK to drive but needs some fine tuning to build more power.



Just thought I would share- I kept track of all the jet/power valve changes (carb is a Quick Fuel 750 blow through) but left that slip in my parts box in the truck. I will update with the jet changes later but I know we changed the power valve from a 8.5 to a 5.5

 

I don't know how that is high tech, but since you posted here I'm going to yank your chain a bit

Jets? Vent tube extensions? Power Valves? BLAH! EFI baby, datalog the run, see what's going on, punch a few keys on the keyboard, be back in line for another pass in ten minutes or less.


Oh, and if you are running that rich and bogged the engine down, the plugs could be fouled and no amount of screwing with the carburetor will work around a fouled set of plugs. The plugs need to be cleaned, changed, or ran on the highway for a good while under fairly lean conditions to clean them up.

---------- Post added at 08:29 AM ---------- Previous post was at 08:27 AM ----------

Oh, I see it's got a set of turbo's on it. Sounds like you have a lot of work ahead of you in the tuning department.

---------- Post added at 08:33 AM ---------- Previous post was at 08:29 AM ----------

What are you running for the ignition system? Spark plug gap? Boost level? Your AFRs will read leaner than they really are if you are getting spark blowout or other mis-fires.

 

MSD 6AL with boost retard box for ignition. We were pulling plugs (granted only two) to check between runs- 7 PSI of boost but it does build boost faster than it can dump at WOT I am seeing 10 PSI. I am working on being able to data log- still need a TPS and tach that will give a digital output or a different digital MSD box. Not enough money in the budget for that yet...

Lots of room for improvement and lots of tuning ahead. Haven't seen an EFI setup that will work on a DIY twin turbo V-8. That would be sweet-

 

Need lots more on your setup.

My first guess you are starting at the wrong end of the tuning spectrum. WOT is the last place to start tuning. Here are a couple of links that may help: http://www.v8buick.com/showthread.php?239017-Blow-through-carb-thread&highlight= and the source http://www.burtonmachine.com/documentationtechnical/

 

$350 will get you an assembled megasquirt box that will do rudimentary fuel and spark and if you have a laptop or netbook strapped in the car it will datalog for you. Then of course you have to DIY an intake for some injectors if you want it to actually control fuel (base model can control spark with minor common mod's). You can still use the carb for the throttle body.

Since I'm spending your money I'd go right to a megasquirt 2 ($432 assembled) or Megasquirt 3 with onboard logging and pile of extra features ($640 assembled). I don't know what you expect to pay for a datalogging system and/or second MSD box, but I would consider that cost versus the MegaSquirt and the megasquirt's expandability.

---------- Post added at 11:05 AM ---------- Previous post was at 11:02 AM ----------

Wait a minute, isn't this a Chevy engine? There are tons of junkyard EFI intake options out there the megasquirt would wire right up too.

---------- Post added at 11:39 AM ---------- Previous post was at 11:05 AM ----------

Sean runs a blow through carb and conventional distributor, but has the MegaSquirt datalogging his AFR's, RPM, etc.

 

I agree that an EFI system would be a great idea!

If you do stick with a carb tough read the instructions part way through this thread:

http://www.v8buick.com/showthread.php?239017-Blow-through-carb-thread&highlight=

Also google "the turbo forums" and they will help you with the tune as well....

For sure get the TPS on the carb! This will help HUGE in your tuning!!!!!!

 

I agree with said above, but lets work with what we have.

First hook up a vacume guage to the intake to see what you have at idle.

Tell me about you ignation system.

Tell me about your whole fuel system.

What carburator are you using?

 

EFI would be a sweet setup but I haven't seen any setups that handle boost well (granted I am only a few weeks into this whole turbo V-8 thing in practice, and only a few weeks of research before that)- none of the junkyard EFI setups will handle 10PSI of boost, will they?

I was thinking more along the lines of a good tach that will have a shift light and digital output- my current setup is a 3" Sunpro Supertach II. I am also wondering if the Sunpro is under reporting actual RPM and the breaking up at 5500 could actually be the "soft" rev limitter of 6K from the MSD box- need to figure this out more.

We have the idle dialed in- it is pulling ~20 inches at idle. WOT launches it was going super lean and backfiring out of the carb until we added the vent tube extenders. Carb hat design has two inlets, one on either side of the front vent. With the extender on it ran much better- but I believe it is going rich at WOT now and bogging down. We re-jetted down on the secondaries but didn't get another run in (as it was I didn't get back from the track until 1:30 AM).

I will have to go take a look at what my fuel pump is- I know it is a high quality mechanical pump that sells for $350 and supports up to 1200HP. Like I said- I just bought the car and am learning all this stuff. My nephew who is helping me tune had built 3 turbo fox bodies that all run 10s or less and is a mechanic by trade.

>>> First hook up a vacume guage to the intake to see what you have at idle. 20 inches at 700 RPM idle

>>> Tell me about you ignation system. MSD 6AL (6K rev limit chip) going to factory HEI dizzy

>>> Tell me about your whole fuel system. Fuel pump I will have to get make/model- but it is running through factory line from tank to engine bay, then 6AN fittings from firewall to pump and pump to carb. Putting in a bigger fuel line is something on the short list of things to do.

>>> What carburator are you using? Quick Fuel Blow Through 750 with Annular boosters. Carb still had factory jetting/squirters and power valve- have upped squirters from factory 33s to 37 primary and 35 secondary. Can't remember the current jetting but have it all written down at home.

Thanks a ton for your help everyone- I am still learning, but I do have an expert in my corner, too bad he is 2 hours away.

Engine is a ZZ4 crate motor that as far as we can tell is still stock. Has two T3/T4 50 trim turbo chargers w/ 2.5" pipes going to big 31" intercooler. Dual exhaust also 2.5" with Flowmasters-

PS>> I have been reading a ton over at Turbo Forums- have not created an account over there yet but been reading for a month or more. Still a ton to learn, obviously!

 

20 inches at idle is pretty good. Tells me some about the cam.

Your right, you need to get rid of the factory fuel lines

The carburator you have is fine just some tuning is needed.

What I am wondering about is the "vent tubes" you talked about.

Maybe you have the floats set to high. Do you have jet extenders on the rear jets?


The factory HEI is not a very good choice, the coil will not produce much current.

What coil do you have ?

Look at your plugs and tell me about them.

 

All megasquirts will take at least 21psi of boost with their built in MAP sensor, and upgraded chips (like the ones I use) will take well over 40psi of boost. All injectors are just a boost referenced fuel pressure regulator away from being boost ready. Almost all EFI fuel pressure regulators will work with boost if I'm not mistaken, at least the aftermarket ones.


As for your current combo, listen to Michael and Sean!! They do know what they are talking about.

 

I have no idea what coil is on there- I guess I will have to check that out. Cam is a complete unknown- I bought the car from a guy who bought it from the guy who built it. He was supposed to get me the builders number but hasn't gotten it to me yet-

Yeah bigger fuel line from tank to the front we talked about this weekend. Just takes money and I don't have much at the moment (just buying the car and all). I believe we are just some tune and tires away from a fast car, LOL. Also it has an exhaust leak on the drivers side manifold- going to replace that this weekend (maybe even the other side if the first one isn't too much of a PITA). The side with the leak had the O2 sensor on it but there was a bung on the other side so moved it there- didn't see much of a change though in the A/F gauge- Car did not have an A/F on it when I got it, and the tach was not working.

 

Do you have a boost referenced fuel pressure regulator? make sure you get a larger return line than your fuel supply line or you will have issues. I know you are short on cash but do not blow up your car due to not having these simple things done right.

 

Yes car has boost referenced fuel pressure regulator and inline FP gauge.

Return line is also factory- again, need to upgrade the lines to and from the tank (as well as put in an easier to reach inline filter).

I just ordered new gaskets for fuel bowls/metering block/carb hat/exhaust headers - and got some slicks so there goes all my extra money for this week.

Wife has me on a short money leash at the moment after spending $10K on the car.

 

Kevin,

How much boost are you making?

Two important guages you need to keep your eye on is a boost pressure and a fuel pressure.

Like Sean said on the fuel lines, the fuel pressure (and fuel ratio monitor) will help you keep from leaning out and buring a piston (s) and/or valves.

Send me some pictures if you can to: sunbuick@aol.com and let me know where you stand.

 

What is your plug gap???

When you say it is rich or lean, can you quantify that??? Jet extensions should only make a difference if you are sloshing all your fuel away from the jets. I don't think you are pulling enough Gs to do that. Something else is going on.. Where are your float levels set??

Jay

 

Sadly I have no idea what the plug gap is. When we pulled the plugs at the track was the first time I ever had them out (remember, I bought the car 3 weeks ago). That is something else I will have to check-

I have wideband installed with AFR gauge right next to the tach- only problem is I am too new at racing to watch it during a run. When messing around in the pit area and launches during warm-up no problem. AFR Gauge/Wideband is an Innovate MTX-L. I also have mechanical boost/vacuum gauge just to the right of the AFR- down below the dash are temp/oil PSI/volt. Fuel pressure is under hood (ideally this would be in the cab, yes).

I have to fix the exhaust header leak- I know that will kill some of my boost- but right now it will build (per the gauge) up to 10 PSI. I thought the internal wastegates were set for 7PSI but found the specs on my turbos today and they are actually 8 PSI.

This winter the plans are external wastgates and boost regulator, roller rockers and some other goodies.

Right now it is running at 13.X at idle, 12.X at moderate throttle and 10.X on WOT- jumps to 16.X or so when coasting. It still isn't building power off the line like it should, but we did bring the jets down a bit after the last run at the track so I believe it is better than it was.

I also got my slicks mounted today- gotta try and get back to the track this weekend to do some more tuning (after putting on the new exhaust gaskets).

Let me know if I can get you guys pics of anything or any other specifics you want- I also have a 1" carb spacer coming- mostly to get rid of the four gasket spacer on there now. Without the gaskets the front accelerator pump hits the intake at rest! I have hood clearance to do a 2" spacer but not sure if the plumbing would allow that much without some modification.

Engine is ZZ4 crate motor with fast burn aluminum heads. Turbos are T04E T34 hybrid- .50 A/R Compressor, .63 A/R turbine side- 50 trim. Sadly, I'm not sure exactly what most of those numbers mean...

The vent tube extensions are 3/8" brake line bent to give a good charge of air to the vents that stick up from the carb- the front vent tube is in a dead spot right between the two inlets of the carb hat, and the carb hat sits very low. The 3/8" brake line slides right over the vents that stick up in the center of the carb- bend in a nice loop and extending the vents 6" down the air inlet piping and lets them get a good charge of air (in theory). That is a trick learned while tuning his two cars - learned from Turbo Forum. Not sure what it does, but it did bring my AFR from lean to rich by just doing that (no jet or power valve changes).

 

Vent tube extensions.. Thought you were talking about jet extensions.. Jeeze how lean does it go without the extensions?? Maybe a couple of more jet sizes on the secondaries would solve that without the extensions. 10.X is rich but should still pull OK..

Those #s aren't perfect, but something else is keeping you from making a big grin..

My car will scream anywhere fron 10.X to 13.X.. I keep it at about 12.3 though..

 

My thoughts exactly- something else is going on. If I thought just messing with the jets would fix it I wouldn't post here I would keep playing with the carb.

We only vented the front due to the dead spot in the carb hat- see pics above. Without the vent tube when you stepped on the gas the AFR was going into the high teens! Trying to go to WOT from idle would backfire and usually die. With just the vent tube we were at 12.X. - bumping up the jets two sizes got us to the 10.X we are at now (we actually went higher first then pulled back one size) on part throttle and 14.x at WOT and no more backfires. WOT was still bogging down- backed off the secondary jet size and still bogs down a bit but not as bad...

BTW- thanks for your help everyone! I don't even pretend to be a mechanic- I am a computer geek by trade.

I am wondering if the exhaust leak (I know the drivers side is leaking bad, passenger side where wideband is on could have a small leak you can't hear because of the big leak on other side) could be messing with what we are seeing on the AFR. New gaskets should be on the way... Nephew said his car with a header leak went from really fast (10.5 in the 1/4) to OK - 12 second car. His car is a whole different beast with 347 stroker motor and one huge turbo.

I will check plug gap- also need to check the coil- but I do not see one at all, only the MSD box and HEI... where would the coil be hiding???

 

First off nice car, with alot of potential. I love the sleeper setup this car has.
Now onto my observations.....I've read through all your posts on the car and notice quite a few things.

First being a ZZ4 motor...10.1 compression, this is alot for a street driven car like yours without a really good tune. I know this motor has aluminum heads and such, but you need to get the tune up running just right before trying to make full passes at the track.

Second you need to get a quality set of spark plugs in this motor, I would suggest 3 heat ranges COLDER then stock, gapped between .025-.030

Ignition timing, be conservative now until your getting close with your tune. About 24-26 degrees total timing.

Fuel, octane what are you running? I'll assume 93. Wish it were alittle higher or better yet E85, is this available in your area?

Boost control, high end controllers are really nice, but lets be realistic. You think the boost is going to high right, well unhook the E clip on the swing valve on both turbos and go for a ride. How high is the boost now? If it still creeps up past 8 then you should consider external gates. With the turbos you have there you should be able to control them down to what you want with just some adjustments you have available now for FREE! You can ajust the tension on the diaphrams on the turbos to make them looser allowing more exhaust to flow around the turbine, lowering the boost level.

As for the turbos you have on there, they are sized good for a street car. I've used just one of those turbos on one of my turbo cars and it would run in the low 12s. So 2 will work nicely. You should be able to tune your car into the mid to low 11s, once you have it all sorted out.

You have an HEI distributor, the coil is inside of the cap.

I will follow along and help as well, I've been running turbo cars for about 15 years now.

Good Luck again and enjoy the car.

 

With the "stock" coil you have I would set the plug gap at 0.027 as long as your running seven pounds of boost at the maxium.