Re: Seems a little slow. Am I expecting too much?

Your 60ft SUUUUUUUUUX. Without that your ET will not be that great ever. Get it down with those tires. You could see as high at 30 deg or iming, maybe a touch more with only 5 psi and an IC and that real 93 you got there. Biggest thing is tires. Las outting with some sticky, but not drag tires I was easily down 10mph in the 1/8. If your spinning, your not spooling, or moving forward.

 

Re: Seems a little slow. Am I expecting too much?

Well I finally got a chance to get the car out to the track last night. Changes made since last year.

-Larger TB
-Dual 3" exhaust from transmission back (striahgt thru mufflers)
-Fixed leaky exhman flanges (huge improvement in boost response)
-275/60 BFG drag radials on 15x9 Weld RTS

The best time from last year before the above mods (copied from original post above)

9 psi, 20* total timing, 10.9 A/F (accidentaly short shifted first a bit). Air was about 55* with about a 10mph head wind
60' - 2.223
330' - 5.766
660' - 8.531 @ 89.26
1000' - 10.9
1320' - 12.886 @ 113.73

The best pass last night

9 psi, 22* total timing, 11.5 A/F, ~75F air temp
60' - 1.927 (Trying to get boost build against the convertor. Could only build maybe 2-3psi before it would start pushing the front tires)
330' - 5.407
660' - 8.145 @ 91.15
1000' - 10.482
1320' - 12.452 @ 114.63

It deak hooked every pass but the best 60' I could get was a 1.904. The convertor was stalling to about 2200-2300 RPM at the line (at 60% throttle according to the data log) but I could barely get 2-3 psi which seem pretty poor for 60/.63 T3s. I could feel the car finally spool up and take off about 60' ft out. I know I need more convertor for sure but shouldn't I be seeing bosot come in faster? These are dinky turbos that should spool nearly instantly. Can the convertor be killing it this bad?

On top of that with better breathing (TB and exhaust), more timing, a leaner A/F, and a 3 tenths better 60' only netted me 0.9 MPH (I was up almost 2 MPH at the 1/8th). WTF? Something just doesn't seem right.

Steve

 

Re: Seems a little slow. Am I expecting too much?

I think your problems are the internal wastegates and the way you have your BOV's mounted, I think switching to external W/G's and mounting the BOVs on the cold sides instead of in front of the turbos. I could eaisly see a 1/2 sec gain by changing those 2 things

 

Re: Seems a little slow. Am I expecting too much?

I got the car out for some passes again last night and made some decent headway. I've figured a few things out since then. I did a compression test after the last track outing an while the numbers were very even from cylinder to cylinder the average was only about 140 psi. This seemed a bit low since I set the car up with 8.7:1. Or so I thought...

I dug back through my math from when I was machining the dish in my pistons and found a calculation error. As it turns out I'm probably actually sitting at right about 8:1. That explains a bit as 22 degrees of timing is probably quite a bit retarded from where it should be. So I started ramping up the timing as I drive it back and forthe to work each day.

Last night I started in with the full load timing map set as follows (22@2500, 25@3000, 26@3500, 26@4000, and 28 at 4500 and higher). With this map I ran the following.

8psi, 28* total timing, 11.5 A/F, 93 pump gas
60' - 1.928 (I REALLY need a higher stall convertor)
330' - 5.368
660' - [email protected]
1000' - 10.332
1/4 - [email protected]

The ET still sucks as the car just will not 60' with the current convertor. I was pleased to see some MPH. It picked up 3 MPH from the last time out. After a few passes I decided to try a few more degrees. I changes the full load timing as follows (23@2500, 25@3000, 26@3500, 27@4000, 29@4500, and 30 at 5000 and higher). Run came out as follows.

8 psi, 30 total timing, 11.5 A/F
60' - 1.945
330' - 5.349
660' - [email protected]
1000' - 10.276
1/4 - [email protected]

I still wish it would ET better as it's probably close to a full second off where it should be but the MPH is starting to look better. I think the ET will come once I get a better stall. I recorded IAT during this run an only saw a 6* temp rise (113F peak) at the end of the 1/4. The IC looks to be plenty efficient.

The piece I'm still missing is that the HP seems to be way off where it should be for the airflow it's moving. My MAFs are telling me that it's moving 57 lb/min but the MPH says I'm only making about 475 fwhp or so. From the HP estimate based off of the MPH it says that my BSFC is only about .64 lb/hp*hr (it was .68 when the timing was 22 degrees). This just seems a bit low. I know you see people say that turbo cars typically run in the .55-.60 range. Does anybody have actual BSFC measurements from a dyno run or something they could share?

Steve

 

Re: Seems a little slow. Am I expecting too much? (Update: Now it's coming around)

I'm digging this one back out of the grave to keep the history going rather than starting a new thread.

After sitting out all last year off due to a dead ECU (My fault. R.I.P SpeedBrain) I finally got the car back on the track. I'm a bit out of practice but after a few runs managed to get a time I'm a bit happier with. The new converter seemed to be the key as the tune is essentially the same even though it's a different ECU. You can see that 0.6 of the 0.7 I gained was by the 1/8 mile, and of that 0.5 was gained by the 330'. Kudos to Pete at Hughes . It wasn't the cheapest converter out there but the stall and resulting performance is right where he said it would be.

8.5psi, 27* total, 11.5 A/F, 92 pump
60' - 1.755 (Leaving with 0psi still)
330' - 4.832
660' - 7.401 @ 95.64
1000' - 9.621
1320' - 11.493 @ 120.23

I think if I load it up a bit harder so that I'm actually leaving under boost it'll be down low in the 11's with no additional boost.

Steve

 

fascinating account ,thank you .more boost should make a big difference .(stating the obvious lol)

 

Just goes to show how iterative in nature this sort of thing can be. Can't wait to see you keep going.

 

Check my sig, I ran 12.6 @ 117 with a soft launch and easy shifting @ 5800 ft near Denver. I don't build boost either just let it sit at 1700 rpm in a t5. I also run a 3" down pipe and dual 2.5" cat back. I use a .81 a/r which I know is too small. What gears are you running?

 

I forgot to mention that I'm running e85as well. I didn't do my own tuning, and I was so excited to drive my car I forgot to ask what the final timing was, but he did tell me he had to take out 8 degree more timing from my 91 octane tune, 91 being the highest here in Denver. And I have a diablo chip with 3 banks and a switch to change the tune on the fly in case I can't find an e85 gas station, which happened twice.

 

Steve,
What tires, rpm leaving at, what rear gear?

 

That's much better. What stall are you running now?

 

NIce!

 

Why is your top speed so low? what gears are you running? The turbo capri on the toohighpsi di 10's with the same setup but had 3.08's

 

I'm running a 3.27 gear and 275/60/15 BFG drag radials on 15x9.25 Weld RTS wheels. The new converter is a Hughes 9.5" that flashes about 3000 RPM when the hammer is dropped. On this pass I only had it at about 40% throttle waiting for the lights to come down which gave me about 2700RPM. I was slowly working my way up on the throttle to see how hard I could push it before it overpowered the brakes with each pass. If I sat there a just bit longer it would have started building boost.

I'm not sure if the top speed question was for me or not but you're correct that my setup is similar to that from toohighpsi. They ran in the 10's on like 15-16 psi with a 351. Once I crank it up to similar boost levels I should be well in the 10's as well. At the boost level I'm running my mph is actually a touch high for the ET. A 120mph trap speed is more typical of a low 11.


Thanks for the positive comments. It's nice to finally get it running respectable numbers. It's took a few years of working out the bugs to get it this far. The converter seemed to be the final piece to unlock the magic. The boost knob will be getting cranked up a bit now (to ~12psi) and the tune dialed in prep for heading back to the track in a few weeks.

Steve

 

i love threads like this keep making progress you will be in the 10's before winter

 

Re: Seems a little slow. Am I expecting too much? (Update: It's come a long way)

Back once again for another update. I ran the car late last year but driver errors prevented me from making improvements. I was able to determine that my low RPM powerband (it starts to fall off at 5400RPM) combined with about 14% convertor slip meant that I was out of gear by ~122mph. So over the winter I changed the 3.27s out for 2.73s and went from a 275/60/15 to a 275/40/17 tire. With the same convertor slip this would net me 131mph capability. It would also greatly improve street cruising which is 99.9% of what this car does.

Anyway, I got it to the track last Friday with the new gears and 10.5-11.5psi and 24* total timing on 92 pump. Car weighs 3600lbs. A/F was still a bit fat at 11-11.2.

60'- 1.64 (left on ~8psi. Foot brake)
330' - 4.627
660' - 7.121 @ 98.3
1000' - 9.283
1320' - 11.110 @ 123.5

I know it's pretty slow compared to many here but it takes me to and from work 5 days a week and can still take corners like the best of them. I'm loving the 2.73s on the street and am amazed that it makes enough torque to pull a 1.64 sixty foot at 3600lbs. I think with a bit cooler day and something closer to 11.8A/F should be enough to get me a 10.999 which is the goal I had set out when I built the car.

Steve

 

Good to see you're still making progress. I've been wanting to try 2.73's, but the consensus was that they would slow the car way down.... Your et, and 60's make me think they'll work good in my 3200 lb car.

 

Thanks. I do think they probably hurt me just a touch in the first 1/8 mile or so. If you have a lazy turbo or a tight converter it probably wouldn't work at all. My 3000 stall (which pretty much held right there with the 3.27s) now pushes up to 4500 in first once I mash the throttle the rest of the way when the light turns green. You can really feel the converter fighting the tall gearing. My turbos are tiny (0.63 A/R stock T3s with GN compressors) and will build full boost before 3000RPM.

Steve

 

Don't worry about the converter slipping... It will NEVER couple with the short gear in it. I ran mine with a 2.76 gear in it for a while, and the slip numbers were crazy at the big end.

Just enjoy what you built it for... if you want it to go quicker... just turn up the boost!

Three weeks ago I ran my 3700lb small block with a S475 on 7~8psi and 16 degree's of timing for some shakedown runs. Leaving at 5psi it went 12.50's. Last weekend I got it back out and turned up the wick. 15~16psi and 18 degree's of timing with a hard launch netted a 9.89@136mph!!!

Just turn it up to overcome your gear... it'll get to 10.99 easy.

 

Have you thought about wiring up a two step?

I've had a few friends that do not have a trans brake and have the same issue pushing through the brakes. So they set the two step right before it starts pushing, usually helps build a few more lbs of boost as well.

It's great to see the improvements from where you were, keep it up!