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I like talking about my build so wanted to start a thread. It is probably going to be light on the pictures as I'm bad about taking them along the way.
Long story is this: February of 2017 purchased a "built" fox mustang from a guy in vegas. Rod/Piston LS3, built 4L80, Comp CT5x 82mm turbo, holley dominator. Went and got the car in person. It drove great and was fast for a street car. Got it home and had Los Vasquez go thru the tune. Fixed a few things and got it on the dyno. Made 853 rwhp at 20#.
Took the car to the track and it went 6.32 @ 118 with a 1.56 60' and about 14# of total boost with an extremely lazy curve. I was pretty happy and looking forward to turning it up. I'm confident the car would have gone 5.99 easily with just more boost and a more aggressive curve.
Unfortunately before I could get back to the track started having issues with the car. Started by the car randomly dying when coming to a complete stop. I would crank it again, fire right up, and be fine all the way home. Eventually this started happening more and more though to the point every complete stop it would die. Diagnosed that the converter was not coming unlocked. Got a pressure gauge on it and it was extremely low. Tried replacing the converter and main pressure solenoids but no luck. Got it dropped and to a local trans builder and he called with bad news. The trans was hurt in a major way. The pump was basically shot which in turn burned up all the steels and clutches, etc. He said he thought it was a thrust issue, which after researching I agreed with. Since that is what we landed on it was recommended I check the motor as well. Put a pry bar on the balancer and was able to visibly move the crank. So got that yanked out and started exploring my options.
I was looking at spending a good chunk of change refreshing my LS3. Was going to put a forged crank in it, ARP mains, pinned mains, then refresh everything. I just never felt comfortable with that though as I knew I would want to turn the boost up and the aluminum LS3 blocks just aren't built for that. You can do it, but I was never comfortable with it actually being reliable. I waffled back and forth several times between fixing the LS3, going 5.3, Dart, etc. Eventually I did settle on a Dart 388 shortblock from a machine shop in South Dakota (non sponsor).
We completely refreshed my 4L80E - New billet main and intermediate shafts, new pump, all new clutches and steels, and we eliminated lock up. Also went to a PTC 9.5" non lock up converter spec'd for a turbo set up.
Motor will be as follows:
Dart Iron LS Next SHP - 4.125" bore.
Molnar 3.622 Crank
Molnar Power Adder Rods
Diamond Race Series Pistons. H13 Pin, Upgraded Rings, Coated Skirts, etc.
Brian Caskey ported LSX LS3 heads. They flow 365/277 at .600.
Tick Stage 2 Turbo Cam for LS3 heads - 227/235 | .624”/.610” | LSA115+5
Johnson ST2116LSR lifters
I don't have them currently but I checked the heads against a 5/16 pushrod and they have a lot of clearance so I'll be going with 3/8 .135 wall pushrods when time comes to measure for them.
I have someone lined up to purchase the COMP 82mm turbo. If that happens I'll be going with a Forced Inductions S491/100.
My goal is to go 5.50's with this car off the footbrake and with this new set up that should be fairly easy considering the power it will make. Should easily make 1200 rwhp and if I feel like pushing it I don't think 1350rwhp is out of the question whatsoever. I'll try to keep this updated every few weeks but it will be a bit slow going to begin with. Feel free to provide any suggestions or input.
Bumping this back up as I'm putting it on the dyno 4/24.
Only changes from the original post are that I replaced the 3 - On3 340 pumps in the tank with 3 new Walbro 525/470 pumps. Should have plenty of fuel now. Also swapped the single adjustable strange rear shocks for high hp small tire double adjustable Vikings. Personal best this past October (before the vikings, with 3 degrees knocked out of everything in boost, and on a very lazy boost curve) with the car so far is 6.02@119 with a 1.39 60'.
Plan is to get timing dialed in on the dyno and see what she makes. I'd be content with anything over 1,000, happy with anything over 1100 and ecstatic with anything over 1200. This will be on a brand new and properly calibrated Mustang dyno. If the tracks open this year, goal is to go 5.50's or faster with it, and still do all the cruising around town I do.
Good luck. Nice looking fox should be able to run 5.50's easy. I've run 5.40's in my 91 notch with my sbe 6.0 and a CRT billet80. Don't know what you weigh. I'm usually between 3175-3185
I'd guess 1200whp and low 5s is doable. What rpm is cam and valve train setup to handle? What rpm did Jose say turbine would generate 2:1 back pressure? I suspect you may be turbine limited on a 388 above 7500.
Good luck. Nice looking fox should be able to run 5.50's easy. I've run 5.40's in my 91 notch with my sbe 6.0 and a CRT billet80. Don't know what you weigh. I'm usually between 3175-3185
Rick
Thanks! Agree the only thing is it is a footbrake car. No trans brake which hurts a little but I'm able to get it on the 2 step and converter up to 3700 and it makes 11 psi for the launch. The car weighed 3080 before with the aluminum LS3 and lighter turbo. With the iron dart block unfortunately I think it's probably around 3200 now. But whatever, it's a street car first, race car second.
I'd guess 1200whp and low 5s is doable. What rpm is cam and valve train setup to handle? What rpm did Jose say turbine would generate 2:1 back pressure? I suspect you may be turbine limited on a 388 above 7500.
Agree on power and times. The valve train is set up to handle 8,000+ in my opinion. I didn't get into super fine details or honestly any details with Jose. I did a bunch of research on my own and wound up with the 91/102 and standard T6 1.32 housing. Honestly probably because Kenny was so successful with the 88/100 on his 388 and a 91/102 must be moar betta right?? haha
I think the turbine has more to offer than that, but I"m certainly no expert. Kenny Dangler had the 88/100 on his original 388 with a much larger cam (not sure if that help or hurts???) and made 1350 to the tire at 26/27 psi and like 82-8300 rpm. This cam certainly won't rev that high. I predict it makes peak power around 7000. Remember it's just the tick stage 2 LS3 turbo cam....227/234. Most people say the 91/102 should be good for another 50-75 at the tires? We shall find out.
This combo should make more than 1200 IMO but it's not the perfectly "matched" combo so I'm giving myself some headway with disappointment lol. Especially on the Mustang dyno.
Welp I'm happy. Not quite what I was expecting but I can't be disappointed. We had a TON of dyno issues unfortunately. This was all on a brand new, 1 month old Mustang dyno and honestly their new software is a joke. Pretty disappointed in that aspect and the fact a 2 hour dyno session turned into a 5 hour dyno session but such is life. It made:
If you do the math 27 psi would be 1100 rwhp on this dyno which sounds pretty spot on for my set up and a Mustang dyno.
Their new dyno cell is very nice as you can see, the issues we were having with the software was the dyno loading the car down wayyyy too much (Mustang said the load we were using was for a dually diesel) so it was causing the car to just blow thru the converter as it never had the chance to couple up. He called and was on the phone with dyno techs for about an hour and we finally got it figured out.
This is the timing mark from the 22.7 PSI pull and 20 degrees timing with an NGK non resistor 8 plug. Pretty happy with that. I think I'm going to stick with the tried and true BR7EF for everything except "on kill" track passes as the 8 is too cold for anything power wise under this.
I think this post is public. Has a few videos of the action. As you can hopefully see it was spinning pretty bad before we strapped it down more and added 2 sand bags to the back.
Nice numbers. Got any dyno graphs to see curves? I totally missed the cam specs you posted. I figure hp starts falling off around 6000. Not sure what I was thinking on the turbine limits, especially at rpm below 6500. You've got lots of turbo left to produce much bigger #s. Your going to have to turn it up or change cam to get it to rpm +8000 to see what it can really do.
Nice numbers. Got any dyno graphs to see curves? I totally missed the cam specs you posted. I figure hp starts falling off around 6000. Not sure what I was thinking on the turbine limits, especially at rpm below 6500. You've got lots of turbo left to produce much bigger #s. Your going to have to turn it up or change cam to get it to rpm +8000 to see what it can really do.
Dyno had an issue with the RPM pick up on this run so obviously the tq is skewed. Really the only thing you can pull info from is the red HP line.
Agree it has more in it. It will definitely make 1,100 + with this set up. I agree it would really wake up with a bigger cam but honestly I like the driveability of the small cam. Plus it's a foot brake car and it currently makes 11 psi on the foot brake and 2 step at 3700 RPM. Bigger cam is going to hurt that for sure. Plan is to just keep adding more boost. I'll probably get in on a dyno day this summer and see what 26/27 or even 30 PSI will do.
Last edited by blackdak318; 04-27-2020 at 01:11 PM.
What are the specs on your pistons? Interested in your comp ratio and how it drives on the street.
They're a standard "flat top" with valve reliefs. So they're like -2.7cc. Compression ration is roughly 10.3:1. Drive great on the street! That is the #1 intention of this car and I've definitely sacraficed some HP for it but not too concerned. It does what I want it to pretty dang well.
Bumping this up again just to give a quick update on the car (if anyone cares? lol)
I did run the car twice with this new set up. It's been a best in the 1/8th of 6.02 @ 119 with a 1.39 60' and about 17 psi total with a stupid lazy ramp. Ended up hurting the 4L80e again. Had it rebuilt and it was great for about 2 weeks then started making another noise. So out it came again. Luckily it ended up just being a bushing rubbing because against my better judgement I let the person helping me talk me into not using the dowel pins in the block. Easy fix though and while it was out I sent the converter back to PTC and had it freshened and we also loosened it up just a hair as it was dropping like 1500 rpm on the shift. It was a 16-0 stator and we ended up going to a 17-0. PTC wanted to go to an 18-0 but I street drive the car a ton and didn't want it to lose drivability. I was able to footbrake and set the 2 step at 3700 previously. PTC says one change to the stator number is worth about 200 rpm so hopefully I should be able to set the 2 step and stall this up to 3900. Not sure I really needed it but on a good track that should be helpful. I was able to make 12 PSI on the footbrake and 2 step at 3700 with the 16-0 converter.
The biggest change to the car has been the cage though. Last winter when the trans came out for the 2nd time I decided to start taking safety seriously and have a true 8.50 cage installed. The car just had what would amount to a 6 point 10.0 roll bar previously. So around Christmas 2020 I purchased a moly 8.50 kit with all the add ons (rocker bars, rear triangulation bars, and torque box bars) from Team Z on their Christmas sale. I tore the interior out and took it to a local fabrication for install. Pretty happy with the install but life caught up with me and getting the interior back in the car this year has been slow. I basically took this year off which honestly has been kinda nice. I'm back to slowly working on the car and making additional upgrades. I just purchased and installed a holley dominator cage mount from Motion Raceworks. I was not happy with how the holley was mounted in the car when I bought it and this new mount is 100x better. I also just recently stumbled across a set of Menscer front struts for a very fair price and somewhat local to me. So I grabbed those this weekend. Currently just had strange singles so hoping these help with the 60' quite a bit. Last year when the car was initially down I also grabbed a CHE 8.8 brace with their added lower control arm mounting points and the Baseline Suspension Outlaw UCA kit. Oh yeah another thing I did in the summer of 2020 was upgrade to a 14V battery and charging system. During my last trip to the track the data log showed very quick (like .01 time wise) drops in fuel pressure. It was a problem the car had had for a while but I couldn't figure out what was going on. The drops and recovery was so fast it never was enough to impact actual AFR. But after looking at my 1008 rwhp dyno pull and reading both on here and some facebook groups pages I realized battery voltage could be a deal. I was never concerned with battery voltage so while the holley was logging it, I never had it shown on data logs. I opened up my last dyno pull and checked battery voltage and there was a clear correlation between battery voltage and fuel pressure momentary drops. Battery voltage actually dropped to like 10.0 at the end of the run. So long story long I swapped out alternators to a XS volt unit from power master and also changed the pulley as to not over spin the alternator. Also swapped to an XS power 14V battery and adjusted the alternator voltage so it charges at like 16.2 volts. It was a GREAT upgrade. Everything electrically works better, my voltage is rock solid now and so is fuel pressure. The car has electric fuel pumps so I have no doubt those are working better as well (I actually had to go in and reduce the fuel pressure at the regulator because after the battery swap the pumps were making more than my desired 43 PSI of base FP due to the extra voltage).
Sorry kinda all over with the above changes and brain dump. But some fairly significant changes to the car over the past year. I'm 100% committed and will have the car done for this upcoming season. I have a feeling there will be a steep learning curve to get the chassis figured out given the number of changes but looking forward to it. I have some good adjustability now and with the baseline suspensions calculators online I should be able to find a decent starting point.
I'm super confident in the engine/turbo/trans/chassis now so plan on actually pouring the coals to it at the track. Goal is to go 5.50 with it in the 1/8th in 2022 and with the parts and power it has already made I absolutely think that is possible. Only limiting factory will for sure be me and my knowledge base. I do have some friends that are pretty to very knowledgeable I can tap into though. As always the car will still remain a probably 80-90% street car that I drive around for fun and take to car & coffee. Hence why I'm not going too crazy with the drag strip goals as although it is not trending much more towards a drag car I always want to keep that true street car base.
Sounds like a great build, I have read your past updates.
What do you think caused the past issues with thrust, too much line pressure?
Great question. I honestly don't know. The motor and trans were built and part of the car when I purchased it. There were some things that lead me to believe the engine build wasn't the greatest though. Namely when I pulled it apart the caps on each rod were clearly ground down, assume as part of the "balancing" process. That is extremely bush league so who knows if crank end play was even checked or what it was. I never checked any of the converter clearances either so who knows what that was like. I basically bought someone else's "built" car and it bit me a little. I'm not too upset though as I was able to recoup a lot of my money parting things out and I also got a good deal on the car when purchased.
11-19-2018, 12:48 PM
Dart 388 S491 Turbo Fox Mustang 
