Here it is, folks! This is really a continuation of my other thread here, in which I documented the build-up of the turbo setup to this point. For those who don't feel like reading through the above thread or looking through my website, here are the essentials of my setup:
SCM61 turbo (GT40 compressor, .60 A/R T04E compressor cover, Garrett Stage V turbine)
Custom 2.5" O2 housing with TiAL 40mm external
Custom 2.5" IC pipes
Spearco 2-216 FMIC
Twin 1G BOVs, modded
3" GM MAF, blow-through config
3" intake pipe with 6" filter (yes I did end up getting rid of that screen)
3" Buschur exhaust
HKS 264/272 cams
Crower valvetrain, SS valves
Stock block
660 injectors/Walbro 255/AFPR
A/C eliminated
These are just some initial impressions, as I don't yet have a lot of performance data.
I got the car driveable yesterday and have been gingerly driving around town. Let me just say that even at the 14 psi I'm running, this turbo is impressive. Now I haven't felt the car in race trim in a while (C-16, 23 psi on the old 16G), but the seat of the pants feeling tells me that the car is almost as fast, if not faster, in its current configuration as it was with the 16G in race trim.
The turbo is very responsive, much more so than I expected. I attribute this to the lack of a pre-turbo restriction, cams, tubular O2 housing, and external wastegate. From a slow roll in third gear, boost begins to build at 3000 RPM. It builds pretty slowly (relative to smaller turbos like the 16G), passing 5-7 psi around 3500 RPM, and finally 14 psi by 4000 RPM or so. You don't hear the wastegate open until boost has reached its peak. Around the top of a gear at 14 psi, I'm seeing about 2400 Hz of airflow on the AFC, and that's with -18% signal taken out.
The power hits hard at 4000 RPM and keeps on pulling/increasing all the way to redline. The experience is quite the opposite of the 16G; that pea-shooter gave all of its punch at once at 3500 RPM and tapered off after that, being practically useless beyond 6500 RPM. The SCM61 is starting to show you its true colors at 6500, and wants to go-go-go without regard to redline or revlimiter. All this at a measly 14 psi! Imagine how it would act with the 25-30 psi it's designed to handle!
The MAF-Translator was truly a plug 'n play affair. I plugged it in, set the base compensation dial for 650s, and the car started right up. I'm still using the AFC (for fine tuning), so when I started to do pulls, I would dial in the correction on the AFC (-18% for Hi, in my case). Afterwards I dialed in the WOT correction factor on the Translator itself (-15%), and put back that 15% on the AFC settings, leaving -3% on the AFC. Did some pulls again and the state of tune was the same, so the Translator correction dials do work. I retained the AFC because it allows me to make RPM-specific changes to the fuel curves. My one complaint about the MAFT is that it really should be in the cabin, not the engine bay, so you either have to extend the wires by yourself or buy their extension harness. I plan to put it in the cabin as soon as possible.
Unfortunately, my testing has been halted because the balance shaft belt broke as a result of one of the pulls. Fortunately, it did not take out the timing belt, and I was able to drive the car home. This is the third time it's happened without harming the t-belt; I've been really lucky. I have tomorrow off, so I'll be rising early to get that belt swapped out (if anyone reading this is in the NoVA area and has a new b-belt laying around, please contact me ASAP!). I know, I should eliminate the balance shafts entirely, but right now I just want to get the car running. It's been down too long for my tastes. Plus that turbo is calling....
SCM61 turbo (GT40 compressor, .60 A/R T04E compressor cover, Garrett Stage V turbine)
Custom 2.5" O2 housing with TiAL 40mm external
Custom 2.5" IC pipes
Spearco 2-216 FMIC
Twin 1G BOVs, modded
3" GM MAF, blow-through config
3" intake pipe with 6" filter (yes I did end up getting rid of that screen)
3" Buschur exhaust
HKS 264/272 cams
Crower valvetrain, SS valves
Stock block
660 injectors/Walbro 255/AFPR
A/C eliminated
These are just some initial impressions, as I don't yet have a lot of performance data.
I got the car driveable yesterday and have been gingerly driving around town. Let me just say that even at the 14 psi I'm running, this turbo is impressive. Now I haven't felt the car in race trim in a while (C-16, 23 psi on the old 16G), but the seat of the pants feeling tells me that the car is almost as fast, if not faster, in its current configuration as it was with the 16G in race trim.
The turbo is very responsive, much more so than I expected. I attribute this to the lack of a pre-turbo restriction, cams, tubular O2 housing, and external wastegate. From a slow roll in third gear, boost begins to build at 3000 RPM. It builds pretty slowly (relative to smaller turbos like the 16G), passing 5-7 psi around 3500 RPM, and finally 14 psi by 4000 RPM or so. You don't hear the wastegate open until boost has reached its peak. Around the top of a gear at 14 psi, I'm seeing about 2400 Hz of airflow on the AFC, and that's with -18% signal taken out.
The power hits hard at 4000 RPM and keeps on pulling/increasing all the way to redline. The experience is quite the opposite of the 16G; that pea-shooter gave all of its punch at once at 3500 RPM and tapered off after that, being practically useless beyond 6500 RPM. The SCM61 is starting to show you its true colors at 6500, and wants to go-go-go without regard to redline or revlimiter. All this at a measly 14 psi! Imagine how it would act with the 25-30 psi it's designed to handle!
The MAF-Translator was truly a plug 'n play affair. I plugged it in, set the base compensation dial for 650s, and the car started right up. I'm still using the AFC (for fine tuning), so when I started to do pulls, I would dial in the correction on the AFC (-18% for Hi, in my case). Afterwards I dialed in the WOT correction factor on the Translator itself (-15%), and put back that 15% on the AFC settings, leaving -3% on the AFC. Did some pulls again and the state of tune was the same, so the Translator correction dials do work. I retained the AFC because it allows me to make RPM-specific changes to the fuel curves. My one complaint about the MAFT is that it really should be in the cabin, not the engine bay, so you either have to extend the wires by yourself or buy their extension harness. I plan to put it in the cabin as soon as possible.
Unfortunately, my testing has been halted because the balance shaft belt broke as a result of one of the pulls. Fortunately, it did not take out the timing belt, and I was able to drive the car home. This is the third time it's happened without harming the t-belt; I've been really lucky. I have tomorrow off, so I'll be rising early to get that belt swapped out (if anyone reading this is in the NoVA area and has a new b-belt laying around, please contact me ASAP!). I know, I should eliminate the balance shafts entirely, but right now I just want to get the car running. It's been down too long for my tastes. Plus that turbo is calling....
