So I've taken the car to the track twice now and would like some feedback on if it's running what it should. I not so worried with ET at this point since i'm just running 245/45/17 street tires. I've only been able to muster ~2.2 60' leaving at idle and rolling into the throttle over about 1 second (verified with datalog). I know the tune is concervative still whcih is holding it back a bit. I drive this car daily so i've been sneaking up on the tune slowly. All runs were on 93 octane.

Quick car specs: Full weight 90 Notch, 351 w/195cc Darts and standalone, C6 w/2200 stall, 60/.63 T3s with large front mount IC.
Build link: https://www.theturboforums.com/smf/index.php?topic=117054.0

First time out: 5psi, 21* total timing, 10.6 A/F. Air was ~68* and dry with a slight cross wind (track is at ~980ft). Made 7 runs all within about 0.02 sec and 0.4 mph
60' - 2.196
330 - 5.891
660 - 8.781 @ 85.98
1000 - 11.237
1320 - 13.313 @ 109.16

I was pretty pleased with the first time out for only 5 psi. Last night I put about 75lbs in the trunk to see if I could leave a little harder on the street tires. I only got two runs in before it started to sprinkle and they ended the test and tune.

Second time out: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

Leaned it to 11.2 for 2nd pass (late into 2nd and bumped rev limiter).
60' - 2.169
330' - 5.679
660' - 8.447 @ 89.26
1000' - 10.814
1320' - 12.817 @ 112.9

I was hoping that with 9 psi and a little less conservative A/F that I would have picked up more than 4 mph. Does that sound right? The goal was to get this car into the 10's with slicks and ~14 psi but I'm a little concerned that 5 more psi is only going to get me to maybe 120 tops which probably isn't quite going to be enough.

Steve

 

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

Well if this makes you feel any better we ran mid-low 10's with a 3000lb Capri with a 351w, out of the box trick flows and those same turbos. I think best mph was 131. They spooled quick but really choked the motor up at the top end of the RPM's. Its in there just ease into the tune.

 

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

First put some damn sticky tires on it!

Just seems to me you should be running those times N/A. From what I see, you would be in the 14's if it was n/a?

That setup without turbos should be in the 12's by itself. Adding boost should definitely get you into the 10's.

I would see what your back pressure is. Something is not right at all.

 

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

I know. I have a set of 26x10 slicks sitting in the garage but still need to get some wheels to mount them on.

I haven't checked back pressure but I do have a boost gage set that I use to read either compressor out pressure or turbine inet pressure. I haven't checked turbine in pressure with 9 psi but at 5 psi of boost I only saw about 7 psi of turbine in pressure. I'll swap the gage around tomorrow and read the turbine at 9psi.

Anybody have experience going from crappy 60ft's on street tires to better 60's with slick that can share how much MPH they picked up? Once I get sticky tires on there will the MPH still stay 113-114 or should I expect to see a few MPH once the 60ft times are where they should be?

Steve

 

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

You might actually drop MPH while getting a better 60ft.

Also depending on how bad you were spinning.

I cut a 1.97 60ft and ran 94MPH in the 1/8. After that run the track cooled down and I couldn't do better than a 2.2 and my MPH dropped to 90-91mph because I was spinning to about 80mph.

 

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

i had a turbo 2.3 5 speed car that ran 8.4 @87 at 18psi and 8.00 @ 91 with stock head and cam and intake with a 57mm holset turbo so yes that seems like something is wrong slicks will tell you alot better story .

 

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

put some timing in it , lean it out , 12-13 lbs ,need looser converter
you are leaving a lot if you want a time slip but if you want a fun driver
lust a little timing will make it a little better.
btw what exhaust is on the car????

 

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

Well the mph is down quite a bit so it doesn't look like it's making much power. What are the inlet temps? My guess is it's either the tune, or those t3's are too small. Imo that thing needs larger turbos.

 

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

I know that my combo isn't ideal with the C6 and low stall both of which hurt me some. However the cars primary purpose is to be a fun but reliable daily driver and a 1/4 mile car secondary. When at the track I'm not actually spinning at all off of the line. I've been rolling into the throttle as quick as I can to maintain traction with the street tires. Intake air temps after the intercooler have typically been no more than 15-20F hotter than ambient and only climb a few degrees during a full pass. I don't think the T3's are quite out of steam (yet!).

I did check turbine inlet pressure at 9psi and i'm seeing about 17-18 psi so while not great it isn't way out of line. I'm only running a 2.5" exhaust with turbo mufflers (I know there's room for improvement there) which run over the axle and out the back. I also took the car to the local landfill and drove it across their scale today. Found out it's a bit of a pig. Scales read 3540lbs with me in it (210lbs) which means with the 75lbs I had in the trunk for traction I was acutally sitting at 3615lbs. Pretty heavy for a notch with aluminum heads and a tubular K-member isn't it? I guess between the subframes, C6, full interior, and all of the turbo/intercooler/plumbing I've added some weight.

I'm not trying to set the world on fire with this car but was hoping that it would get into the high 10's at least by the time I get to 14 psi. I've seen plenty of others here run that or better with less displacement. I'll have the slicks ready for next spring at which point I'll take the boost higher and work my way up in timing and leaner in A/F to see where that gets me. I may have to put it on a bit of a diet this winter too.

Steve

 

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

That is a pretty heft Notch.

I would just wait to do anything until the slicks are on and you get some good numbers.

I know a better stall would be a night and day difference.

 

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

i had almost the identical setup. differences below

vr jr intake
8.5:1 cr
383 not 351
c4 3000 stall
N/A no turbo yet
3.55 gears
ms2
voodoo 276 cam
85 capri w/ junk in the trunk.

heres a vid of a good run with it
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same engine in a gutted car
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Re: Seems a little slow. Am I expecting too much?

not trying to bust your balls but trying to shave a second and a half off with 5 more psi will be hard unless you put that car on a diet

 

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

He has about 6-7 tenths from putting a sticky tire on it and getting the 60 down to at least the low 1.70's.

 

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

Mabey u need more turbo/boost. I m running a bone stock 90 hatch with a 60mm 10 psi same shitty tires leaving at idle (traction issues when the boost kicks in to) and Im running 13.2@109mph at 3800ft granny shiften the old t5. I feel right now slicks would cut off a good second. Hows your car spool up? Is it pretty slow or more like instant boost? 351 with heads I would think u whould be more 120ish at 9psi even with shitty tires

 

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

http://tomak3.tripod.com/page5.html

Link to a local guy that runs an old icon kit at 9psi. 12.2@125 with mild 302 and street tires. I dont know if your exhaust would hold u back much duel 2.5 turbo mufflers should do the job. Although I had 2.5 inch flowmasters (wich suck) when I first went to the track they felt like they were holding the car back. Just for comparison sakes I cut them off just added staight pipes. Exhuast is full catback and tail pipes MPH went from 105 to 109 same 13.2 though, stupid tires. Best 60ft with the old kumhos was 2.189 but usually in the 2.2 to 2.5 range.

Just read your build thread. Sweet diy on a buget you have some skills. Clean looking stang, I like the intercoole, its hudge . Do u have any overheating problems on the hi-way? IT looks like the intercooler blocks the whole rad off. How much hp can twin t bird turbos support?

 

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

The difference my car sees from a good launch to a bad launch is alot. When I was tuning at 5 lbs of boost, I could footbrake the car to a 2.05 60' and go 8.00 ET in the 1/8th. Now on a better 1.5X 60', the same tune would go 6.90s. Thats 1.1 seconds faster in the 1/8th which would be about 1.7 seconds in the 1/4 mile. On paper it doesnt make sense but thats what happened.

 

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

Well I have a few changes planned for the winter. The first change is some slicks . 26x10's on 15x9 Convo Pros so leaving under boost now should be an option. Fitting of the rimss also revealed that the cheap Summit 2.5" tailpipes wouldn't allow the slicks to fit. The tail pipes rubbed even though I barely have to touch the inside wheel well. So since the exhaust has to modified anyway I decided to upgrade to 3" from the transmission cross member back. I'd like to do full turbo back but the 3" would be tight with where I have the down pipes routed (damn giant C6 trans pan doesn't help either).

The other big change will be the throttle body. I knew the stock 65mm TB I used from a 2V 4.6L was small but I didn't realize how much. I had noted that I was dropping 3 psi from the compressor outlet to the manifold. For the size of the IC i'm using that seemed like quite a bit. I found some flow figures online and it turns out that it only flows 500CFM @ 20" of H20. I have a twin 57mm TB from a 4V 4.6L which according to the same site should flow over 900 CFM. I think that should make a significant difference.

Turbo5point0, with the e-fan on it stays cool on the highway. I took a bit of work though. I've sealed the entire nose of the car so that all air entering must go through the IC and then the rad. I'm working on improving the cooling this winter as well as I'd really like the fan to mostly be off anytime I'm moving over 30 MPH. I think part of the problem is that now the hot air coming off of the rad is getting pulled out to the fenders where the air filters are at. During cruise the IAT is warm (20F over ambient) but when I open the throttle the temps drop instantly by 15F.


Steve

 

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

Steve, Something we did to my brother's car may help your clearance issues. We cut the trans crossmember just to the Left side of the mount & welded on another "large hump" from the Right side of a spare crossmember.The bracket on the floorpan needed moved toward the outside (you can see the weld where it was put back together) & the floor bumped a bit with a rubber hammer. This allows a straight shot for a 3" or 3 1/2" pipe to run past a C-6. If your going to go to 3" pipes back behind the crossmember...just do it right now & be done with it. Leaving the smaller pipe from the turbo to the crossmember is defeating the purpose, the backpressure is still there. Hope this Helps, Lorne
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Re: Seems a little slow. Am I expecting too much?

I like those Convo Pros, I was looking at picking up a set. I was thinking more like 15x8.5 with some 275/50/15 et streets

 

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

You seem to have your timing real conserative also, crank it up some and just set the AFR at 11.5 and forget it.

My combo on 6 psi i used to run 27* under boost.