PD Supercharger top end? Butt dyno question
 

I’m saving for a supercharger kit and supporting mods at the moment—I’ve read every thread I could find but couldn’t find thoughts on this question. Dyno graphs aside, does a positive displacement SC like edelbrock feel weak up top? I know it provides more torque down low as opposed to the JRSC building to the top end but looking for thoughts from anyone whose driven one.

I have EL headers with a modest tune and love the surge up top, but would like more midrange grunt. Five million forum pages later I still can’t decide between Edelbrock and JR—with Edelbrock would I lose that top end “Surge” feeling? I guess as a secondary question is the midrange torque difference with the JR centrifugal sufficient for just a bit of extra oomph in a DD?

I really need to find someone local to try out both options. I apologize in advance if these are dumb questions, I’ve never driven an FI car. I usually keep in around 3500-5500 rpm but love love love hitting redline to wring the power out when I get the chance.

I have the Edelbrock and it does NOT drop off at all up top. Yes, it provides more boost at midrange than the Rotrex blower, but it keeps pulling hard all the way to redline. Based on your described usage, it sounds like you would prefer the Edelbrock over Rotrex.


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Vortech
 

Hey sir

I have a Vortech supercharger and It has what you are looking for It pulls all the way to redline making more boost as the RPMS go up. As for roots style I know the boost is flat so what you feel downlow you may feel the same if not a bit more up top.

As for a centrifugal supercharger Like the vortech kit. The boost keeps building and maxes out at redline.

i ll suggest you the edelbrock, as a owner of a unrestricted centrifugal supercharger with about 1.1 bar of boost at redline

you will love the torque under 4000 rpm with the edelbrock or you will hate the torque under 4000 of the centrifugal

They all build boost with RPM, a centrifugal SC will build boost more progressively though, a PD blower is less progressive but still builds more boost with RPM as you rev out.

a PD blower can flatline torque, and people have made over 400whp on PD blowers.

You don't feel HP you feel torque, the rate of rpm change or acceleration is determined by torque. HP is a derivative of torque. if a car make more top end HP that is because it makes more torque at that RPM.

A PD style blower gives you a lot more options for configuration in how you want your power delivery. you could flatline torque and it will just pull all the way through to redline, you could purposely detune the low/mid range to limit peak torque but then keep top end torque somewhat higher and more closely mirror a centrifugal blowers power delivery.

If both setups make 300whp peak the PD would walk all over the centrifugal.

Is there a torque limit you feel comfortable reaching?

A PD blower is pretty much better in almost every way for a DD/street car

A centrifugal blower will most likely be better for tracking as they are a little more efficient (less work for same power) at top end and you can run an air to air cooler and not worry about heat soak as much like an air to water setup usually suffers from. There are options for preventing heat soak on air to water but it adds cost and complexity.

I’m comfortable reaching around 220lbft once I pull the trigger on a SC. I’m installing a stock clutch atm (current clutch/flywheel is way aggressive for my current NA setup), and hope to run that OEM clutch and stock internals for a while, so 220 will be plenty for me. As I said I love the top end my EL headers are giving me at the moment, so I may enjoy a rotrex unit like a Jackson C30, but low torque sounds nice too. I would love to ride along with some other Seattle-area 86 owners and see how PD vs centrifugal feel first-hand but I have no idea how I’d go about setting that up. I appreciate your input

Thanks for the input man. I do love the top end my el headers give me, so centrifugal is also appealing. I really need to find a way to feel the difference first hand with some other 86 drivers. This decision is stressing me out and I’m not even ready ($) to buy one yet lol.

Air to air
 

You can run pd with a fmic air to air. I did...

Jaden

I mean anything is possible i guess.

Any pics?

There's video...
 

Yeah I made a video and posted it in the car journals...

https://www.ft86club.com/forums/show...55#post3504455

Or here's a direct link

https://www.youtube.com/watch?v=tvuHmT2Q0U4

Jaden

Not your traditional setup, especially for a PD blower, and twin PD blowers at that, pretty unique, that whine is pretty sweet.

So a PD blower provides a set amount of air per revolution, where as a centrifugal blower is progressive, as rpm rises so does the amount of airflow.

Boost is a measure of restriction of the engine. With centrifugal type blowers and turbocharger compressors, they have lesser or greater efficiency depending on the level of restriction of the engine and the rpm. Most producers will run tests and provide compressor maps of their products. This will give you an efficiency level based on the pressure ratio and the rpm of the turbo.

You can determine what efficiency your combination will likely be at by understanding where your combination will fall on the compressor map.

Now, with either type of compressor a lot of top end versus low end power and how it comes on will depend on the N/A power curve. This is because the amount of air the engine can ingest at different RPMs will affect how efficient the compressor is at providing air and what boost the car will be running.

IOW, there will be combinations where a PD will provide higher boost at higher rpm and combinations where it won't. Regardless, with a PD blower, you will know EXACTLY how much air it's providing at any given rpm.

My setup provides 1000cc's/revolution. So everytime it spins over it provides 1000cc's of air.

I was able to use this knowledge to estimate exactly how much boost I would get. This allowed me to choose the right pulley for the superchargers to get where I wanted. With FMIC losses, I max out at about 8 psi. Which is right where I calculated it would be.

So, if your car ingests a disproportional higher amount of air at the top end versus the lower end, then it will have less boost at the top end with a PD blower, if it ingests less at the top end proportionally, you will have more boost, but for every revolution you are getting the same amount of air, it is fixed.

Jaden

my Sprintex 210 continuously built boost as you revved out and peaked at 13psi at redline.
from what I've seen the TVS1320 does the same building boost to redline.

As an Edelbrock owner, I'll say that I absolutely love the way it pulls hard all the way to redline. Mine currently kicks in hard about 3000-3500rpm, and it's just fire the rest of the way through the revs.