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I already have a tough time hooking at lower speeds, a PD would only make that worse.
A CSC will never have extra power or much of any power down low. Using a smaller pulley will bring the CSC in sooner as in mid band, about where you are getting good hook.
I want more boost sooner (mid band) but to not go over 750 WHP.
Why does no one use this? Other than me, who wants to throw away power? LOL
I have never liked the idea of a restrictor plate. That is a guaranteed way to create more heat. The air pulled into the CSC is thinner (lower pressure) so it takes more compressing to get the the same level boost. If I remember correctly A&A advises against using a restrictor plate for this reason.
And I do have a **** if I ever want to go for more.
Question is why do you not want to go over 750 rwhp? More power at a lower RPM is harder on things than more peak power at 7000 rpm. Let the centri do what a centri does pulley it to spin passed max recommended impeller speed at your shift point and make all the power it can.
As mentioned I run an 8.25 crank and 3.55 blower pulley spinning it 66,000 rpm which is 4,000 passed max recommended impeller speed what would I be gaining by limiting peak power? Nothing.
Want more midrange or low end with a centri? Either use a bigger cubic inch motor or a different head unit like an F1a or F1a-94 or larger. They have a different step up ratio and will make more midrange power. Stop trying to make a combo do something it isn't meant to do and pick the correct combo to achieve your goals. Everything will be happier!
I have never liked the idea of a restrictor plate. That is a guaranteed way to create more heat. The air pulled into the CSC is thinner (lower pressure) so it takes more compressing to get the the same level boost. If I remember correctly A&A advises against using a restrictor plate for this reason.
And I do have a **** if I ever want to go for more.
First off, no issue with the blower bleed system. I think it is a clever setup and I like the **** - just not something I need right now.
Regarding the discharge temperature, it actually doesn't work like that. If that's what A&A said, they are also not correct. A restrictor plate can cause surge if not sized right, but it won't heat the air more.
Your compressor heat is set by three things - discharge pressure of the compressor, compression efficiency and inlet air temp. The higher your discharge pressure, the higher your discharge air temperature. Running a bleed valve puts a higher discharge pressure at the blower, hence a higher discharge temperature, vs. a setup that prohibits the blower from getting up to the higher pressure in the first place. It gets a little more nuanced than that, but that is the fundamentals.
Isn't the SDCE Crank pulley 7.25" ?
That would put your blower spinning 64244rpm at 6700rpm
I used to think it was 7.25 as well. Not sure of their later stuff. This is one measures out to a smidge under 7" bare. It is about 7" and 1/16th top-to-top with the belt on. The belt guard, top-to-top is about 7.25, but that isnt where the belt runs.
Years ago (2008?) I used to run a 3.3 pulley and stepped down to a 3.1 when I realized the crank pulley measured a little smaller than I thought.
I love the bov/WG idea on centri blowers that don't focus on 1/4 mile racing, especially with a stick. Obviously limiting boost won't win races, but part throttle/tip in is so much more fun having more of a step change in boost than the linear ramp of a centri. Turns the boost curve into a turbo. My turbo ls6 makes way more power than my DD, but the DD is a blast to drive ever day because of the small twin turbos that will make 15 psi at 2800 rpms. No launch control, 2 steps, trans brakes, etc. Big block/PD type torque is fun if you aren't concerned around max ET.
I love the bov/WG idea on centri blowers that don't focus on 1/4 mile racing, especially with a stick. Obviously limiting boost won't win races, but part throttle/tip in is so much more fun having more of a step change in boost than the linear ramp of a centri. Turns the boost curve into a turbo. My turbo ls6 makes way more power than my DD, but the DD is a blast to drive ever day because of the small twin turbos that will make 15 psi at 2800 rpms. No launch control, 2 steps, trans brakes, etc. Big block/PD type torque is fun if you aren't concerned around max ET.
What if you’re already spinning the blower passed max impeller speed? What is to gain by limiting peak boost? I’m already reducing timing down low as I come into boost to aid with traction. Adding more down low wouldn’t help me.
All this theoretical talk, but I’ve not met anyone with a wastegated centri that liked it and kept it that way.
ETa: The race track is an actual measure of performance we can see the numbers and compare with known data. Saying you don’t care about that data and using subjective terms like seat of the pants of throttle response isn’t something we can compare and authenticate online.
I went 6.18 with a 1.4x 60’ on a prepped track in September 2020 at 3900 lbs. Now I have more power at about 5 psi more boost better intake and meth injection yet only went 6.7x with a 1.9x 60’ on my first experience on no prep. That was leaving off idle and rolling into it. Second pass left a little harder off idle just rolled into it faster again 1.9x 60’ but got sideways when I hit wot and lifted. Now I’ve replaced my seats with racing seats and cut some more weight so I may be around 3600 lbs, but hope to hit the track again when it’s prepped to shoot for 5.9x. Low end isn’t my problem tip in on the street results in wheel spin on drag radials in 2nd gear. This is with a setup that is known and admittedly not a low rpm torque monster. At some point over 800 rwhp on the street adding more low rpm torque actually is a negative.
What if you’re already spinning the blower passed max impeller speed? What is to gain by limiting peak boost? I’m already reducing timing down low as I come into boost to aid with traction. Adding more down low wouldn’t help me.
All this theoretical talk, but I’ve not met anyone with a wastegated centri that liked it and kept it that way.
ETa: The race track is an actual measure of performance we can see the numbers and compare with known data. Saying you don’t care about that data and using subjective terms like seat of the pants of throttle response isn’t something we can compare and authenticate online.
I went 6.18 with a 1.4x 60’ on a prepped track in September 2020 at 3900 lbs. Now I have more power at about 5 psi more boost better intake and meth injection yet only went 6.7x with a 1.9x 60’ on my first experience on no prep. That was leaving off idle and rolling into it. Second pass left a little harder off idle just rolled into it faster again 1.9x 60’ but got sideways when I hit wot and lifted. Now I’ve replaced my seats with racing seats and cut some more weight so I may be around 3600 lbs, but hope to hit the track again when it’s prepped to shoot for 5.9x. Low end isn’t my problem tip in on the street results in wheel spin on drag radials in 2nd gear. This is with a setup that is known and admittedly not a low rpm torque monster. At some point over 800 rwhp on the street adding more low rpm torque actually is a negative.
Again, all your data is 1/4 mile related which I specifically excluded in my initial post. You're focused on max boost at max rpm. Of course you'll go faster with more boost at peak RPM....exactly where you race at. How much boost do you make at 3000 rpms? Your response is that you don't race at 3000 rpms and that your torque converter is higher than 3000 rpms so you never see it. That exactly the point of where a wastegated centri setup shines. For people who want low end area under the curve and don't launch the car. It turns a centri setup into a turbo car without all the mess of a hot side and heat to worry about. It's 100% NOT for you.
What if you’re already spinning the blower passed max impeller speed? What is to gain by limiting peak boost? I’m already reducing timing down low as I come into boost to aid with traction. Adding more down low wouldn’t help me.
All this theoretical talk, but I’ve not met anyone with a wastegated centri that liked it and kept it that way.
ETa: The race track is an actual measure of performance we can see the numbers and compare with known data. Saying you don’t care about that data and using subjective terms like seat of the pants of throttle response isn’t something we can compare and authenticate online.
I went 6.18 with a 1.4x 60’ on a prepped track in September 2020 at 3900 lbs. Now I have more power at about 5 psi more boost better intake and meth injection yet only went 6.7x with a 1.9x 60’ on my first experience on no prep. That was leaving off idle and rolling into it. Second pass left a little harder off idle just rolled into it faster again 1.9x 60’ but got sideways when I hit wot and lifted. Now I’ve replaced my seats with racing seats and cut some more weight so I may be around 3600 lbs, but hope to hit the track again when it’s prepped to shoot for 5.9x. Low end isn’t my problem tip in on the street results in wheel spin on drag radials in 2nd gear. This is with a setup that is known and admittedly not a low rpm torque monster. At some point over 800 rwhp on the street adding more low rpm torque actually is a negative.
Agreed on the traction issues. Running a RaceTCS system to stop me from going in the woods at 90 mph. Somewhere in the 700-800 HP power range, low end torque starts to not be helpful - even in with a good tire and suspension.
It's been a few months since you posted this, How has your experience been since? Are you happy with the move to the d1x, or was the car more fun to drive with the D1SC. I'm back and forth on which one to get for my Silverado. I feel like I'm leaving something on the table getting the d1sc, especially given the newer d1x technology
I miss the low-end gut punch of the D1SC. However, the D1x makes traction less of a problem - which is nice. The only problem with the peaky D1x is the boost that I get into now. Car runs ~22 psi on pump gas on a cool day. It is an 8:1 compression motor, so it seems to work fine with 93 and it isn't getting over 20 psi until 6,000+. Beat the garbage out of it all summer and plugs, etc... looked fine with the higher boost. Overall, happy with the swap. The butt-dyno indicates that the car makes notably more power when it is wound out.
Motor is coming out this winter for a freshening. Motor has been putting out ~800+ HP for around 18 years now and ~50k miles.....so it is time.
I can add my input as well. I recently changed from the d1sc to the d1x. My car is an 02 ws6 T/A. 346ci stock bottom end, 11.1 CR, 228R cam, cncd 243 heads, 1 3/4 headers, Magnaflow catback, twin 4.5" intercoolers. I run an alky control 100% methanol system and one 6oz of boostane with every fill of shell 93. I had my car dynoed at new england dyno back a few years ago and put out 601rwhp (spark smoothing was on) and timing didnt have much more than 13-15 degrees in it. That was with the d1sc on a 4.5" pulley making around 8 psi with belt slip. I pullied down to a 4" and did some wideband street tuning and moved it up to 10-11.5psi and added in some timing. The car felt very responsive out of boost and as Nogo said, the low end kick of the d1sc is amazing and something i sort of miss. Fast forward to this past year, replaced my worn out D1sc and upgraded to the d1x. Same 4" pulley, with the d1x the boost moved up to 12.5 psi at 6800 rpm. I have 15 degrees of timing in it at peak boost. The out of boost throttle response is still there because its a 11.1 CR motor but it really needs to wind out to get into boost, above 5000rpm it really wakes up and pulls hard up top. The issue now is my cam, its not evacuating the exhaust and i feel i would benefit from a wider duration cam on the exhaust side to take advantage of the new power up top.
I am in the process of building a forged LS3, 10.1 CR, 224/236 cam and worked PRC cncd heads. I will keep psi around 15 until I go with a FMIC.
In short, the D1x really needs to be spun hard to move the boost up in the lower rpm ranges. Over all, I believe its a great blower with alot of potential. I never did max out the D1sc so I'll never know its true potential, which Is why you cant go wrong with the d1x if your starting from scratch.
before this post i never would have considered a d1sc , i figured id go from my p1sc-1 to a d1x but this has me thinking . I already feel the car needs a little more low end power and if i went d1x i think it might feel like i have to rev it to the moon all the time . Thank you for spending time and doing this . i think a p1sc-1 to a d1sc will be a good choice.
before this post i never would have considered a d1sc , i figured id go from my p1sc-1 to a d1x but this has me thinking . I already feel the car needs a little more low end power and if i went d1x i think it might feel like i have to rev it to the moon all the time . Thank you for spending time and doing this . i think a p1sc-1 to a d1sc will be a good choice.
There are many things to consider. More cubic inches and more compression will move the power curve. Also when you pulley the blower so it's spinning max or beyond max impeller speed you also gain more midrange. With 20 psi peak using a D1x on a 10.6 to 1 377 I'm pulling timing to limit power as it comes into boost and still struggle with traction at the track. I don't feel like more low end would benefit me at all I can spin the tires at will when playing on the street and struggle with traction at the track with a D1x that is not known as a low end torque blower. At lower boost levels the D1x did seem to leave something to be desired as far as low end torque, but once I went to the 377 and 20 psi I was happy not to have any more low end. Car was tuned on the street and track so I don't have any numbers, but mph suggests near 850 rwhp.
From: Saskatchewan, Canada - where arguing "DA" is for the slow and weak...
I have a wastegated (50mm) set-up on my D1SC'd stock long block LS2 TBSS. Works a treat. It is pullied down to bring the boost in quickly to 5-6psi on spring pressure, and if I add manifold pressure to the dome it goes right up to 12psi. The boost/rpm map above suggests it is set up correctly for daily driving and track duty in such a heavy vehicle.
It is also a blow through MAF (hybrid) set up. Just doing everything wrong I guess?
Swapped superchargers from a D1SC to a D1X. I wanted a quiet drive and wanted to put a little more into the car. Ran a couple logs and built what the two different boost curves look like.
D1X setup is with a 4" inlet. D1SC is with a 3.75" inlet. So, not 100% apples-to-apples comparison, but pretty close. If anything it would have made the D1SC more pronounced. Combination is a custom Procharger installation on a 383 all-bore engine with a large front mount (1,500 CFM). Setup makes ~700 HP D1SC and ~800 HP D1x. Boost curves are ambient/pressure corrected to 1.013 bara and a 75 deg F day (former gas turbine engineer, so the correction is actually done right). So, that part is apples-to-apples.
Inlet air temperature rise for the D1SC dT is ~35 deg F and D1X dT is ~25 deg F. So, the D1x does show up as a much more efficient (cooler) blower. From the below curves it can clearly be seen that the D1SC is a much stronger low-load performance blower, while the D1X is more of a 'peaky' blower. The car does feel a little softer down low, but it continues to pull up top where it nosed over with the D1SC - which is exactly what the curves show.
So, in summary - if you want area under the curve and don't care about a peak number, go D1SC. If you want that peak number or do all your business at 5,500+ rpm, go D1X.
did you measure temps after compressor? must be quite a good cooler bringig delta temp down to 25° (from 200°+). what are you using?
Dyno'd the car the other day. This is max speed D1SC to max speed D1x comparison (62k rpm vs 62k rpm). Old setup, 383 all-bore at ~16 psi to 418 at ~21 psi car went from ~700 RWHP to 851 RWHP (same static compression, very similar cam). Had to swap the motor to larger cubes to bring the boost down on pump gas - was running 24+ psi when it got cold out (too much) on the smaller motor with the D1x. Also, ran out of fuel up top (capped out 2x 340's, upping it to 2x 450's) and had a little belt slip, so car should have put down closer to 900 RWHP.
Overall, decent little blower that seems to be worth ~150-200 HP increase over the D1SC.
Nice! I absolutely love the D1x probably the most impressive centri as far as power at its size with low IAT's. I moved on to the F1a-94 and definitely gained significant power from the mid-range all the way up over the D1x, but I don't dyno my car so I can't say how much it actually picked up.
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