Track times on new setup. Help me find my bottleneck!

JDSfastGN

Well-Known Member
I went to the track for the first time in about 5 years this past Saturday. Weather was good for this time of year at about 900-1000 ft DA.
My previous best had been an 10.70@127.8 on a basic combo.
Girdled 8.8:1 234 ci,
ported stock heads with bigger valves,
210/215 FT roller, PTC 17 blade,
6776 23/21 timing and 25 psi.
Home-made FMIC (ebay core w/no leaks)
Alky/93.
28x9 Hoosier bias ply slicks
3.23 gears

After hurting my old setup I came across a fresh 249 setup I couldn’t pass up. My new goals were a 10.20@132
My new combo is a 9.0:1 249 stroker
“THS special 6768 dbb with a 3”x2” cover
21/18.7 timing with 28-29psi
1.65 roller rockers
Same iron heads freshened
218/212 roller
Full -8 feed, -6 return dual fed fuel system
PTC was tightened to a 16 blade with a sprag added to try and help it to couple efficiently.
28x9 MT ET Pro Bracket radials
Dual nozzles added to alky
3.23 gears
All runs were off the Tbrake
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Saturday I started off poorly with the car surging through every gear and ran an 11.3@114 with a 1.58 60 on 23-25 psi
I turned the alky down from 6.5 to 6 and took some fuel out of the base fuel setting on my TT 6.1 chip. (My powerlogger didn’t record so I couldn’t see what was happening BLM wise at WOT so I took a chance. Scan master showed 10.5 a/f as the leanest with 1* knock

Next pass I cut a 1.52 and it went 11.00@122.5 and boost was 24-25 down low and 26-27 in 3rd . The mph seemed really low for the boost and combo so I went and tweaked the fueling again
IMG_5164.JPG


I pulled alky back to 5.5 and made a pretty clean pass and a new best by a hair. 10.61@127.43 with a 1.49 60 ft launching at 13-14 psi. This time I actually got my powerlogger to record and I saw it was actually trying to add roughly 10% fuel throughout the run.

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10.61 PL.png

I added base fueling back into the chip and added a 1* of timing overall. I ended up getting on the brake but had to back off when the other driver had issues with the tree and pushed through so the trans probably got warm. This run felt weird and fell off significantly to a 10.955@122.9 despite 28-29 psi and a consistent 10.5+/- a/f. The BLMs this time were starting to peg out at 170 to try and keep in line with my target a/f ratio. I knew something wasn’t quite right but really wanted to compete in class racing that was about to start so I went to make one more pass to see if I was gonna stay and compete.
10.95 PL.png



I added base fuel up to 22% and left it all alone. I let it cool off for about 30 minutes or so and put my fuel pressure gauge in the windshield. The car left hard and pulled another 1.49 60 ft with about 15 psi off the trans brake. The car was pulling smooth and strong but what I assume was around the 1000 ft mark I saw my a/f ratio take a dramatic turn upwards to 14.1:1. I reacted slowly and kept in it through the run I’m pretty sure looking at the logs. Car seemed fine and registered 0 knock during the incident. The BLMs were pretty solid at 124 until it went lean and it tried to react. I tried to read the fuel pressure gauge but it had slid down a bit and the lighting was so poor I couldn’t see if it had dropped or not.
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10.67 LEAN.png


The bottle necks I can think of
Ported 62mm stock TB and matched plenum- not sold on this being an issue as many have gone much faster

Ebay intercooler (slightly bigger than an RJC) IATs are kept in check and generally drop from a bit over ambient to below ambient mostly due to Alky. I don’t know if the turbo is pushing 40 psi to get to 29-30 in the plenum

Big Valve Ported Irons, I really thought 28-29 psi would put me in the 6768s sweet spot but would I need 31+ to reach my goal on Irons?

Converter- Despite being a tight 16 blade with a sprag added 9.5” PTC I am seeing slippage up near 14-16% using the TCI calculator and my trap speed (Ignore any power logger mph since it’s based on my 25.7” tall street setup) On the higher boost settings im seeing about 500-650 rpm drop down to 4950-5000 rising to 5700 or so through the traps.

Shift points- I could probably benefit from taking some weight off the governor and getting shift points up near 5900-6000 but I’ve never had it on a dyno to see where it peaks and starts to really fall. I’d imagine peaking at 52-5300 or so. I can feel the 1-2 shift during the runs but it’s not very obvious on the logs as it shifts a bit earlier around 5200-5300. The 2-3 was between 5500 and 5700. The trans felt solid throughout the evening.

*All passes have been done on a 3” MAF pipe and 3.5” LS1 sensor and translator and TT 6.1 chip.
 

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JDSfastGN

Well-Known Member
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rag231

Well-Known Member
The gears are working for your combo but why did you pick 3.23's. When I tried those my car just didn't 60ft well. 3.73 created too much tire spin ( and shufflin') and trap rpms. The car just operated better with the 3.42, I am using a turbo 350 tho. What is your launch rpm?
 

JDSfastGN

Well-Known Member
The gears are working for your combo but why did you pick 3.23's. When I tried those my car just didn't 60ft well. 3.73 created too much tire spin ( and shufflin') and trap rpms. The car just operated better with the 3.42, I am using a turbo 350 tho. What is your launch rpm?

A combination of wanting to race the car on the short 315/35r17 drag radials I run on the street and not having to shift into OD combined with the NL converter it makes for a nice highway cruise rpm still. The difference is pretty small comparing a 3.42 to the 3.23 and can be made up for with a 27" stall tire if need be. Launch rpm showed to be around 4200 or so at 13-14 psi.
 

getdowngranny

Mr. Fix It
Do you have the alky off or the speed turned down during staging?
Are you opposed to turning up the boost?
AFR readings seem a high.

I would lean out the launch, pull timing on the top end, and add boost (2-5psi) after verifying your AFR is tracking as it should.
 

JDSfastGN

Well-Known Member
Do you have the alky off or the speed turned down during staging?
Are you opposed to turning up the boost?
AFR readings seem a high.

I would lean out the launch, pull timing on the top end, and add boost (2-5psi) after verifying your AFR is tracking as it should.

Alky is on the whole time but is progressive and smooth. It doesn't give any issues building boost or down low. Im happy with the 60 ft. The car is not the greatest setup for drag racing but I have no doubt i could have launched even harder and the tires would have held. AFR is 10.5 througout most of the runs with the exception of the end of the 10.66 pass. Ive always targeted 10.4-10.5 in high gear. Im not opposed to turning up the boost once i get a 4 bar map hooked up but I feel like its a bandaid for a setup that should run more mph at the current 28-29 psi.
 

getdowngranny

Mr. Fix It
Alky is on the whole time but is progressive and smooth. It doesn't give any issues building boost or down low. Im happy with the 60 ft. The car is not the greatest setup for drag racing but I have no doubt i could have launched even harder and the tires would have held. AFR is 10.5 througout most of the runs with the exception of the end of the 10.66 pass. Ive always targeted 10.4-10.5 in high gear. Im not opposed to turning up the boost once i get a 4 bar map hooked up but I feel like its a bandaid for a setup that should run more mph at the current 28-29 psi.
The alky pac controller has a purple wire that if you wire a relay to ground the wire while building boost at the line (t-brake/two step button) it'll slow the pump down and keep you from over alkying it at the launch keeping the correction down. You can see on the log that its leaving fat.
 

JDSfastGN

Well-Known Member
Im curious why you think valve springs? These were setup to handle the cam and the car shows no signs of valve float? K750s have always worked well for me. These are iron heads, not aluminum that would need a lot more seat pressure.
 

JDSfastGN

Well-Known Member
Search spring pressures and Bison...

I will see what i can find as Ive done tons of reading over the years with regards to Bison. He knows his stuff but again there is no sign of any issues with the springs... I'm not hitting a wall or having it stutter like you would expect, in fact it revs just fine to 6000 at 130 mph on my street tires. These springs were installed at 1.65 and had over 145 seat pressure if I remember correctly I had about .056 before coil bind even with the 1.65 rockers. Thanks guys, keep em coming.
 

Boost231

What's An Intercooler
Staff member
IMOP don't worry about a bottle neck find out what's wrong with your car. I would start with verifying fuel pressure and checking your alky pump pressure. I can't see your logs but lack of tunning knowledge will get you in trouble. Ypur making very large changes.

Sent from my SM-G935T using Tapatalk
 

Pronto

Chaos is a ladder.
The BLMs are super lean. Like above check fuel and alky. As far as boost, bet that Ebay intercooler is restricting 5psi. Turn the boost down and take that timing out until you find why you suddenly went lean. Again, start logging fuel. Much better than trying to look at a gauge on the windshield.
 

JDSfastGN

Well-Known Member
IMOP don't worry about a bottle neck find out what's wrong with your car. I would start with verifying fuel pressure and checking your alky pump pressure. I can't see your logs but lack of tunning knowledge will get you in trouble. Ypur making very large changes.

Sent from my SM-G935T using Tapatalk

Lol I consider myself an above average tuner, i just don't post much anymore. Ive had this car for 18 years and the changes to the tune were overall minimal as the chip has the ability to add 33% fuel to reach my target a/f. I only added fuel to the starting point of the chip so that the chip could track the Wideband easier. The chip would benefit from Eric adding more fueling into the base map but on a cold morning Ive seen it add 20% fuel on a pull and then when its 78* on the way home its pulling out 4%.
The most i did was add a degree of timing to see how it responded. Not until the last run did something drastic happen to either the alky/fuel pump or the wideband sensor. I will get to the bottom of the fuel issue but I am more concerned with the lack of overall mph on the earlier passes where there was no issue. I expected 105mph 1/8th and 130mph 1/4 at least from 28-29 psi with a billet 6768. I do have both a new map, and fuel pressure to wire into the powerlogger in the next few weeks though. Thanks!
 

marleyskater420

still needs to learn
What is your suspension setup on the car? Front and Rear.

If you are running a 3.5" MAF with a 3" maf pipe, that definitely is not helping. Lookup on Ebay the seller Earlbrown (also a member of this board) he sells a complete 3.5" MAF pipe kit for like $75 I believe, which is a solid $30-40 cheaper than most other places. Buy that kit and install it. That will remove the most glaring bottleneck that I can see.

Are you able to monitor what your backpressure is on the headers right before the turbo? That is something that I would also have installed. Here is a link to a good, affordable pressure transducer that you can install in your headers. It is $50 for the sensor and the plug/wiring. https://perfecttuning.net/en/accessories/49-pressure-transducer-sensor.html#/15-cable-yes Here is a link for a good stainless steel 1/8" bung to weld onto your headers: https://finishlinefactory.com/product/npt-weld-bung-stainless-steel/

Do you have a pressure transducer to monitor your fuel pressure? You can use that same pressure transducer I posted above for your fuel pressure transducer.

If your concern is that the FMIC you have is a bottleneck, I would install this MAP sensor in 2 spots; 1 spot right after the turbo in the pipe going to the intercooler. The 2nd spot in the pipe coming from the intercooler to the throttle body in the same location/ near where you would have your alky nozzles, but do it BEFORE the alky nozzles so that they do not interfere with the reading. This way you can monitor the pressure drop across your intercooler core and see how restrictive it really is. If you are seeing any higher than a 6psi pressure drop, you should consider buying a new core or complete FMIC kit altogether. Here is a link to the MAP sensor I am telling you about: https://perfecttuning.net/en/gauge/323-100-psi-map-sensor-7-bar-18-npt.html#/15-cable-yes now you can also use the pressure transducer I posted above, but you have to remember that the pressure transducer does not factor in the atmospheric pressure, whereas the MAP does. So the pressure transducer might read 34.7psi coming out of the turbo and 30.7psi going into the throttle body. Since the pressure transducer does not take into account the 14.7psi atmospheric pressure, you have to remember that for whatever reading it gives you..so that 34.7psi is really 34.7-14.7=20psi, you follow?

If you intend on getting a few of the MAP/Pressure Transducers, let me know, I'm a dealer for that company (and the Finish line Factory that sells the NPT Bungs) and I'll help you out on pricing so you don't get hit with such a high cost merely because you're trying to tune your car in a more informed manner.

Just something to keep in mind on a side note, if you're looking for something to not only help you monitor your sensors, but also help reduce the amount of gauges you have, checkout this gauge: https://perfecttuning.net/en/gauge/69-universal-gauge.html It can monitor up to 3 different gauges/inputs along with the battery voltage. You can setup pre-determined alarms for each of the 3 inputs in case your car goes out of what you would deem "safe"- so you can set up the boost pressure input (if you choose to have that as an input) so that if your car makes over 20psi the gauge's alarm will go off, notifying you of this so that you can abort the run and re-tune your boost controller. Same goes for all 3 inputs you have to the gauge. It is a pretty cool gauge that allows you to monitor multiple inputs with just 1 screen, helping to reduce all the clutter of having multiple gauges for monitoring purposes. Plus it has an analog output to connect to something like an external ECU or a Powerlogger (if you have any available analog inputs on the PL left).
 
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