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We were getting belt slip with a 7.65 crank pulley and 3.9 blower pulley so psi was only 8 lbs at 600 rwhp.
Since then have replaced 7.65 pulley with a CBR 8.65 crank pulley, moved idler pulley on Aster Bracket, and replaced Mishimoto 26 X 12 X 4 inch FMIC with the Camaro Procharger 26 X 12 X 4.5 inch intercooler (see pic below). Also removed two silicone connectors in the charge pipes with welded connections for better flow and less restriction.
I have no doubt that the ATI intercooler will add more boost and is more efficient than the Mishimoto intercooler. The larger crank pulley should reduce belt slip and also increase blower rpm and boost and still be under max D1SC impeller rpm with the 3.9 pulley. Still running the Gates green belt with plans to switch to the Gates RPM blower belt when I finalize pulley size and belt length with the green belt.
Will be interesting to see the results. I'm thinking boost will be somewhere between 8 to 12 lbs.
Goes on the dyno next week. Will report results for the OP when running with cats, a single I pipe and Magnaflow catback. Will get some videos while on the dyno.
Dyno operator and tuner is still the same (Dynojet Eddy Current Load Control two-wheel dynamometer - similar to a Mustang Dyno). So will be an apples to apples comparison when dynoed previously.
ATI Procharger intercooler with AC condenser relocated off the face of the radiator (still run AC and was getting 34 degree at each dash outlet last week with ambient temps at 102 F).
Note: I'm not looking for max rwhp - another 50 to 75 RWHP is enough. Car drives nice with a Yank 3450 blower converter, Performabilt level III 4l60E tranny with 3.23 gears.
Here's a video of my Z28 on the Dyno. I expected more rwhp but was only making about 11 lbs of boost compared to 8 llbs for boost with the 7.65 pulley and Mishimoto intercooler. That said the larger crank pulley and change to the Procharger intercooler added 3 lbs of boost. It started to drop off at 6250 rpm so might have gotten a little more boost at 6500 rpm. At 6250 impeller rpm was:
As you can hear, the vented red race valve isn't nearly as loud the as the big red race valve I originally had installed that is not vented. And there isn't any rasp from the exhaust after adding the shorty Magnaflow mufflers. So it makes nearly 630 rwhp, is reasonably quiet and doesn't wake up the neighbors, no rasp and drives and has very good street manners. Plus the ac blows nice cool air and the engine doesn 't overheat like a lot of Procharged systems.
So to answer the OP's first post - yes you can make over 600 rwhp thru a single three inch catback (Magnaflow) with a decent set of headers with cats (ARH products).
IMO - to make 700 rwhp I need to switch to less restrictive LS3 heads and LS3 intake with a 90 mm TB. Current heads are TSP PRC 225 cc heads with 68cc chambers. Cam is TSP 227/234 600/600 114+4.
Last edited by dlandsvZ28; Jul 7, 2021 at 12:21 PM.
Reason: edit content
Here's a video of my Z28 on the Dyno. I expected more rwhp but was only making about 11 lbs of boost compared to 8 llbs for boost with the 7.65 pulley and Mishimoto intercooler. That said the larger crank pulley and change to the Procharger intercooler added 3 lbs of boost. It started to drop off at 6250 rpm so might have gotten a little more boost at 6500 rpm. At 6250 impeller rpm was:
As you can hear, the vented red race valve isn't nearly as loud the as the big red race valve I originally had installed that is not vented. And there isn't any rasp from the exhaust after adding the shorty Magnaflow mufflers. So it makes nearly 630 rwhp, is reasonably quiet and doesn't wake up the neighbors, no rasp and drives and has very good street manners. Plus the ac blows nice cool air and the engine doesn 't overheat like a lot of Procharged systems.
So to answer the OP's first post - yes you can make over 600 rwhp thru a single three inch catback (Magnaflow) with a decent set of headers with cats (ARH products).
IMO - to make 700 rwhp I need to switch to less restrictive LS3 heads and LS3 intake with a 90 mm TB. Current heads are TSP PRC 225 cc heads with 68cc chambers. Cam is TSP 227/234 600/600 114+4.
Yea that Bypass sounds very quiet! I like it. Exhaust sounds really nice too.
Just for reference Im running a forged 346, 10.1 CR
untouched 241s with double springs
Ls6 cam
Ls6 intake and TB
Pacesetter Lts, 3" ORY into a 4" I pipe, over the axles, back out into dual 3" tails with Dynatech mufflers. 6" long body.
D1SC 8.65" crank, 4.25" blower and I make 15psi (15.7 in 60* weather) thru the twin 4.5" intercoolers
It put down 678rwhp with a fuel issue way up top. I got that fixed now, might be able to squeeze a few more out of it but Im very happy with it for being such a mild build.
I don''t want to go off topic in this thread so am sending you a PM.
If you look at the torque and hp numbers in the dyno graph in the video the torque numbers are way off. Perhaps HP as well. IMO this engine should be making more than 624 rwhp and more boost with the pulley combination and high end ATI intercooler and ATI red bypass valve (it shouldn't leak when making more than 10 lbs of boost).
Last edited by dlandsvZ28; Jul 8, 2021 at 09:37 PM.
Reason: edit content
dlandsvZ28, any power you picked up I'd venture to say was through the pulley change but still seems a little light on what you "should" have gained. Put into perspective, changing from a 4.0 to 3.9 blower pulley would net 1,420 blower rpm increase and I think rule of thumb is around 1psi increase, you gained 6,570 rpm changing from the 7.65 to 8.65 crank pulley assuming a 6250 engine RPM (that is close to 5 blower pulley size changes). I'm sure there is certainly a benefit to the IC change (improved air temps and possibly less psi drop) but keep in mind you already had a large intercooler.
And without a doubt your current combo can make 700whp, there is absolutely zero need to switch heads and cam setup. I'd venture to say if you bumped that exhaust up to 3.5" you'd see a gain with nothing else changed. I think you might see 13-14psi running it out to 6700ish which "should" move that whp # up higher but it's a balancing act trying to get it all through a catted 3" singe exhaust.
30th t/a seems to be more in-line with where you'd be at if you did the above.
Setup I ran:
As built from GM LS2 (longblock untouched other than Katech rods bolts which were probably not needed)
Thunder Racing LS2 cheater cam (VERY mild compared to your cam 215/230 - 600/578-116)
Trunion upgraded rockers
Stock TBSS intake
1-7/8" headers with ORY
4" mufflex exhaust
4L70 auto/3400 converter
13ish psi (Novi 2000 blower which is similar to D1SC)
16-17* timing
93+meth
688whp/579wtq
Last edited by ALL ULL C; Jul 9, 2021 at 12:43 PM.
Thanks for the info - that's what I thought at well for HP.
A very good source who has done 100's of dyno session with Prochargers tells me he thinks the dyno is set up wrong. He doesn't think it's possible for the torque to be 150 ft lbs over max rwhp. Look at the graph at the end of the video for example:
The graph shows that torque jumps to 751 ft lbs at 3500 rpms, but total HP at 5K is only 624. Another source today who has done hundreds of dyno sessions on a Mustang dyno says that the dyno was not set up correctly. That's why the torque numbers are out of line and perhaps rwhp hp too.
And based on his mistake to not understand how to copy in the values for IFR for a boosted motor suggests that maybe his calculation for boost is off as well.
I downloaded the HP custom 98 pcm tune and he did it again. He copied in the values for an NA static FPR instead of one value across the board for my boosted engine with an Aeromotive 1:1 FPR. For my Deka Signature 80 series flow tested injecters the value for 58 psi should be 92.41 in all cells in the IFR table. And he didn't copy over the other tables for 80's either, he left them at 60 Mototron values.
Because we thought I might go above 80 percent duty cycle because of extra boost and increase in HP, I installed Deka 80 series injectors and changed the Hobbs switch to activate from 7psi down to 4 psi. I have Racetronix dual 510 lph fuel pumps good for 1k HP.
So before I go and spend more for upgrades I think I need to find another tuner.
As for the exhaust - I hate rasp. So I might consider true duals. Not sure if I want to remove the ARH cats however. The exhaust IMO sound good now and is not obnoxious with a lot of rasp up to about 40 mph.
Last edited by dlandsvZ28; Jul 9, 2021 at 12:38 PM.
Reason: edit content
I know that typically Mustang dyno's are a little more conservative/stingy on that number so hitting a DJ would probably bump those numbers up. And I would agree that TQ with a centri blower would not over-take HP anywhere in the curve. I like seeing what the dyno #'s "show" but it's always at the track where the tell-tail is in your mph vs race weight.
Sometimes you have to take a step back and look around. Have to protect what you have vested in your ride and some of us put a lot of confidence into someone that they have the same vested interest. I know enough to be dangerous in the tuning department and have a little bit of smarts when it comes to logging and reading what the vehicle is doing.
Yeah I'm more of a deep rumble Magnaflow/Borla XR-1 kinda sound and not Corsa oh my god are you outta your #%cking mind sound. True dual 3" would 100% uncork it if there is any restriction now.
I know back in my Buford (GN) days that ATR's 3" single shot exhaust could be upwards of 600whp but you are also talking 3.8L vs 6.0L.
Thanks for the info - that's what I thought at well for HP.
A very good source who has done 100's of dyno session with Prochargers tells me he thinks the dyno is set up wrong. He doesn't think it's possible for the torque to be 150 ft lbs over max rwhp. Look at the graph at the end of the video for example:
The graph shows that torque jumps to 751 ft lbs at 3500 rpms, but total HP at 5K is only 624. Another source today who has done hundreds of dyno sessions on a Mustang dyno says that the dyno was not set up correctly. That's why the torque numbers are out of line and perhaps rwhp hp too.
And based on his mistake to not understand how to copy in the values for IFR for a boosted motor suggests that maybe his calculation for boost is off as well.
I downloaded the HP custom 98 pcm tune and he did it again. He copied in the values for an NA static FPR instead of one value across the board for my boosted engine with an Aeromotive 1:1 FPR. For my Deka Signature 80 series flow tested injecters the value for 58 psi should be 92.41 in all cells in the IFR table. And he didn't copy over the other tables for 80's either, he left them at 60 Mototron values.
Because we thought I might go above 80 percent duty cycle because of extra boost and increase in HP, I installed Deka 80 series injectors and changed the Hobbs switch to activate from 7psi down to 4 psi. I have Racetronix dual 510 lph fuel pumps good for 1k HP.
So before I go and spend more for upgrades I think I need to find another tuner.
As for the exhaust - I hate rasp. So I might consider true duals. Not sure if I want to remove the ARH cats however. The exhaust IMO sound good now and is not obnoxious with a lot of rasp up to about 40 mph.
If your dynoing the car with the converter unlocked, I believe that will show the torque extremely high compared to the HP, just as it looks in your case. If you lock the converter, your numbers should be very similar to as what a 6 speed would show.
Another member on this site named "AFASTYZFR1"
made 765rwhp with his forged H/C 347 and a D1SC thru his 3" magnaflow catback.
FWIW, I'm currently running a 3 in. exhaust out of my vs racing 7875 turbo with bent *** exhaust to a magnaflow catback. I was making around 770 on 18 psi with some little pcv routing issues. I fixed the routing of my catch can and added a electric cut out. Ended up making 849 RWHP/ 869 Ft-lbs TQ on the same 18 psi.
FWIW, I'm currently running a 3 in. exhaust out of my vs racing 7875 turbo with bent *** exhaust to a magnaflow catback. I was making around 770 on 18 psi with some little pcv routing issues. I fixed the routing of my catch can and added a electric cut out. Ended up making 849 RWHP/ 869 Ft-lbs TQ on the same 18 psi.
thanks for the good info. When I read numbers like this thru a 3" catback, it makes me wonder if the 4" exhaust is needed.
thanks for the good info. When I read numbers like this thru a 3" catback, it makes me wonder if the 4" exhaust is needed.
I mean If your running a turbo you can run into some back pressure issues like my current v1 Huron turbo kit blows collector gaskets all the time when I run it with the cutout closed and try to race. I'm currently swapping over to a Huron v3 kit, and I'm keeping the 3 in downpipe to the cutout because of how quiet it is, but If I was going for max HP, I'd be running the biggest exhaust I could lol.
That’s pretty solid right there! Was the 849 through the cutout or actually through the exhaust?
Originally Posted by Cocaine_Bird
FWIW, I'm currently running a 3 in. exhaust out of my vs racing 7875 turbo with bent *** exhaust to a magnaflow catback. I was making around 770 on 18 psi with some little pcv routing issues. I fixed the routing of my catch can and added a electric cut out. Ended up making 849 RWHP/ 869 Ft-lbs TQ on the same 18 psi.
On another motor setup in an FD RX-7 we built using an LS3 block, stock crank, Carillo rods, Wiseco pistons, ported SDPC LS3 heads, stock LS3 intake, 90mm TB, Precision Gen1 GTS76 (1100hp rating), Treadstone 3.5" intercooler we made just over 1000rwhp with single 3" downpipe that near the rear axle had an e-cutout into a 3.5" pipe. When closed it went thru an ultra quiet 3" RX-7 muffler (Racing Beat twin tip). Car went 9.3@162mph maxed out taking it easy on the launch with this turbo on pump e85. T56, 3.31 gears 8.8" IRS, around 3100lbs with driver. That motor was sold to a buddy and now the car has an LS9 block with MAST LS3 heads and Precision 88mm T4 turbo (1400hp rating) we have yet to max out. Went easy 9.3's@163mph with tons left on the table.
This is a great post and am loving the information, experiences with different setups. Any sounds clips to anyone’s cars? My old setup in my 94z was stock LT1 with deletes, Fuel upgrades , spark, intake ported for 52mm TB, heads ported/polished, S-trim vortech, computer tune. Had Mac midlength headers, 3”ypipe, offroad pipe, into a SLP Loudmouth 1 catback. It was loud as crap and loved it. New motor in the works is a 03 LM7, that will have a blower of some sort, blower cam, headers not sure what size. My goal is 500rwhp-600rwhp. My question is to reach that goal could I reuse the same setup but do 1 7/8 mids, 3” ypipe, off-road pipe and 2 1/2” catback?
Thought about running true duals as well, or 3”-3.5” catback. I’m worried about the sound with any of these setups and don’t want to spend $400.00 and hate the sound. Also love not seeing a muffler! I have the SLP CME tips so I would have to do TD or catback regardless now that I think of it. Would old exhaust be to small?
Lots of good info here. Im going to be running a twin turbo setup and I am trying to decided what to run myself for exhaust. I definitely want it free flowing and have good ground clearance.
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