When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Just posting this up as a point of reference. As a note, the driveshaft was causing some vibration, so pulls were made in 2nd gear (1.625:1 gear ratio) rather than in 3rd (1:1 gear ratio) to keep the driveshaft speed down. As a result, power numbers are lower.
ECM:
0411 ECM swap
12216125 OS with 2bar Speed Density
EFI Source 3bar MAP
Boost:
Huronspeed V3 AC T4 turbo kit w/ 8psi spring in wastegate
VS Racing cast wheel 7875 turbocharger
Custom 4" cold air intake
Open downpipe exiting under DS floorboard
The plan moving forward is to swap the driveshaft out, put in a full exhaust, and add a boost controller. I want the next dyno test to be done in 3rd gear and see if I the 340lph pump and injectors will support ~15psi on pump E85.
That was just 8psi. From what I’ve read, there’s more parasitic loss through the drivetrain when you dyno in a lower gear, and probably vise versa in higher gear than whichever gives you 1:1. My Trans Am had some clutch issues when I had it on the dyno, and it went from 413whp to about 380whp when we tested it in a lower gear, but that was with a T56.
Sweet setup! Love seeing results of "real world" results.
Maybe I missed it, what intercooler and did you open up the gap on the rings?
I believe the intercooler is from XSPower, as is the wastegate and BOV, which is what came with the Huronspeed kit. The BOV was giving us issues so it was swapped with a spare that the shop has, but I don’t know what brand.
I rebuilt this engine with new rings gapped for boost, somewhere around .020” top and .025” second. I also used coated OEM main bearings from a Gen V LT4 and coated OEM rod bearings from an LS3.
I got a good aluminum driveshaft in and it seems to have fixed the vibration. I cut a hole in the hood and ran a 3” pipe up and out of it with a Tractor Supply rain cap.
TX2k is coming up and I need to get tags and plates on it, so I welded up the full exhaust and got it installed, just waiting on a silicon coupler to put the MAF in so it’ll pass the OBD-II inspection.
It has to do with gear multiplication/leverage and the way the dyno reads/feels TQ. You can run the same car in 3rd, 4th, 5th, 6th, gear and get 4 different power numbers.
You take a car, run it, swap the rear gears to something deeper, put it back on and it will show a lower number.
I have another date with the dyno scheduled for Friday. The car is now in "street legal trim" with a full exhaust and MAF sensor. I put in an AEM boost controller too so we'll see how much this little 340lph pump can support. I have the regulator set to a base pressure of 40psi and I'll put in some 93 octane to squeeze out a little more.
I have another date with the dyno scheduled for Friday. The car is now in "street legal trim" with a full exhaust and MAF sensor. I put in an AEM boost controller too so we'll see how much this little 340lph pump can support. I have the regulator set to a base pressure of 40psi and I'll put in some 93 octane to squeeze out a little more.
New results are 535whp @ 14psi with the little 340lph pump at it's limit. The car was dyno'd again in second gear, not because of driveshaft vibration, but because the rear gear ended up being 2.73:1 which would be about 177mph had it been run in third gear.
Obviously those aren't numbers that are gonna set the world on fire or anything, but it does make for a fun street car. We didn't have time Friday to get tags to make it officially "street legal", but we were able to take it to Houston Motorsports Park that night and set the record for slowest turbo LS.
This is why we don't race dynos lol.
On the first pass (left slip), I left at about 1700 RPM and didn't see 8psi until about 3 seconds out. I tried to leave at a little higher RPM on the second pass, but I think something broke in the rear so I was off the throttle pretty early in the run. I have a 9" rear with a 3.55 gear in it, so the plan is to swap the rear and get back to the track next weekend.
02-08-2021, 11:07 AM
1999 Camaro Z28: Turbo 4.8L 
