Do you regret choosing your power adder?

[Wolfys11]

Someone better tell this guy that centrifugals aren't good for drag racing!

Just because it was done doesnt mean its the best way to do it. Your intake can be made from home depot pvc piping and a roll of bounty paper, just cuz ur car made 1000whp doesnt make your intake “great”

A turbo is the middle ground, you get low end power for a launch with 2 step and get high end with the turbos boost

A whipple has a ton of low end, which can be too much since its hard to limit a whipples low end power when you make a ton of power

A centri has trouble with low end power to launch, once its going its good, but its 60’ isnt going to be great unless you launch at an ungodly high rpm which is going to be worse for the engine, the transmission now needs to be running a different way like a torque concerter or a clutch that slips a decent amount in order to make a consistent launch at that type of rpms

While your at it, find me the fastest ecoboost since you know everything about them too, im curious what that community has done since youre so good at clipping the top .01% of cars to make your arguments

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[engineermike]

I do know people are able to do boost by gear with PCMtec. Watched a video in a thread on here where a member has it. So if I go pd, that will definitely help with traction.

Yes, I do boost-by-gear, boost-by-drive mode, and even boost-by-% ethanol. Works awesome!

 

[Wolfys11]

Yes, I do boost-by-gear, boost-by-drive mode, and even boost-by-% ethanol. Works awesome!

Do you tune pd only setups or do you do turbos/ centris?

 

[Milktasd]

Just because it was done doesnt mean its the best way to do it. Your intake can be made from home depot pvc piping and a roll of bounty paper, just cuz ur car made 1000whp doesnt make your intake “great”

I did have a friend with an old 280z make an intercooler piping setup from Home Depot pvc . It actually held up to 7-8psi if I remember. 11-12psi not so much.
Was hilarious. Was before I had a cellphone, wish I had a picture of it.

 

[Milktasd]

out of curiosity since the throttle-body is on the low side of a PD instead of high pressure like everything else, does the ECU feather the TB (and or play with advance) to choke off the intake and thus regulate measured <> desired torque?

you would have to ask one of the tuners who use it, I have no idea.
I’m not smart enough to tune it at the very least too lazy.

 

[Zrussian13]

Just think of how much more valuable research Mike could have done for the 6g community these last two weeks if he wasn't stuck providing facts around his data on this thread.

 

[Wolfys11]

Just think of how much more valuable research Mike could have done for the 6g community these last two weeks if he wasn't stuck providing facts around his data on this thread.

?
Nobody said he has to respond or participate
Nor was it a waste of time for us all to debate 30 pages here
One setup or another, theyre all great and the only debate is if one is .1% better than the other or not. Im sure if he was so busy he wouldve stopped participating a long time ago

 

[Zrussian13]

?
Nobody said he has to respond or participate
Nor was it a waste of time for us all to debate 30 pages here
One setup or another, theyre all great and the only debate is if one is .1% better than the other or not. Im sure if he was so busy he wouldve stopped participating a long time ago

But that's pretty much what he's tried to say over and over. He never said whipple was better but tried to show using "heat soak" as an excuse why cenrtis were better was not the case anymore. He even made the comment in certain cases either one could out perform the other. It's not a clear cut case of one is better than the other. Also my comment was strictly just one guy having a little fun poking the bear. Nothing anyone should be taking too seriously.

 

[robvas]

A whipple has a ton of low end, which can be too much since its hard to limit a whipples low end power when you make a ton of power

A centri has trouble with low end power to launch, once its going its good, but its 60’ isnt going to be great unless you launch at an ungodly high rpm which is going to be worse for the engine, the transmission now needs to be running a different way like a torque concerter or a clutch that slips a decent amount in order to make a consistent launch at that type of rpms

So do you think the fast Whipple cars don't use an aftermarket converter?

 

[Wolfys11]

So do you think the fast Whipple cars don't use an aftermarket converter?

Fast whipple cars use far less launching rpm than centris do

 

[engineermike]

out of curiosity since the throttle-body is on the low side of a PD instead of high pressure like everything else, does the ECU feather the TB (and or play with advance) to choke off the intake and thus regulate measured <> desired torque?

Short answer is that boost-by-gear/rpm/drive mode/ethanol is all accomplished with throttle modulation. The stock coyote ECU (and by extension basically all SC calibrations) are constantly controlling airflow using throttle modulation until about 83% (typical) pedal, where it transitions into pushing the blade wide open regardless of torque request. In order to do boost by gear or drive mode, you have to disable this torque over-ride and have it always modulated to a desired torque. In order to do boost by rpm or %ethanol (flex), you can keep the WOT torque over-ride and use airload limits which also modulates the throttle.

Do you tune pd only setups or do you do turbos/ centris?

I've done mostly PD, followed by NA, then turbo, then centrif. I haven't attempted torque modulation on centrif's though, so it would take some testing. The issue is that the throttle body airflow model has to be very accurate. I usually have to dial in the throttle body model first, which could take 10-30 iterations, before it would work. Furthermore, the PCM logic calculates throttle angle based on TB characteristics, upstream pressure, plenum pressure, and desired flow. The upstream pressure is assumed to be barometric, so with a centrif and turbo this is incorrect. It may not even be possible without throttle inlet pressure (TIP) logic like the ecoboost has.

 

[engineermike]

Just think of how much more valuable research Mike could have done for the 6g community these last two weeks if he wasn't stuck providing facts around his data on this thread.

Lol....not that anyone cares but my control-systems friend and I are trying to see how far a "simpler" fuel system can be pushed on E85 and high boost. As of now, the setup is a single DW400 pump at 22 volts and DW95 injectors running E85. It's a Whipple GenV 3.0 car currently on a 3.0" pulley (18 psi boost) and has some system overhead even in cooler temps. Trying to balance the port injector and fuel pump duty cycles now, which will result in more fuel available still. This setup relies on modification of the fuel pressure feedback control loop.

 

[Angrey]

Actually, I could argue this either way. Take for instance that Whipple's peak efficiency chart shows the 2.9 at 78% and the 3.3 also at 78%. They've said the 3.0 is higher, so let's just call it 78-80%. Of course, we're assuming they aren't outright lying, but the efficiency numbers are in line with what Eaton is telling us and that large OEM-supplier is unlikely to lie about it. ESS doesn't give us any efficiency numbers or maps, but they have told us max cfm and we know the approximate inducer diameter. These numbers line up very well with the Vortech JT-B, which we do have maps for. The JT-B peak efficiency is also advertised at 78% peak. I do realize we don't have great data on either one, but this example just shows the PD can be a little higher, a little lower, or the same.



Absolutely. Once again, we can compare similar units. The Eaton R2650 is run at "peak minus about 2% efficiency" at our pressures/flows/speeds. If you assume the same for the Whipple 3.0, that would put us at 76-78%. With the ESS, again assuming the Vortech JT-B is close, we can plot the operating point on the map and see it's in the 75% range.

If anyone has better curves or more applicable comparisons, please post them up. This is the closest I could find and is only used to demonstrate the point that they aren't very far apart.



Also true! We already showed the difference between 70 and 80% has a fairly small effect on the engine brake power.



For sure!

See, I'm going off my own biases or previous information. I'd find it very curious that any typical centri blower is operating in the less than 80% adiabatic efficiency range.

We are saying its worse because you have to “make it work” with other stuff added, just because you can make it work doesnt mean its a good way of doing it. Il quote you from before, very few record centri setups, one of the reasons is because of the high rpm launch needed

What you're essentially arguing is that the centri is more efficient, but you're leaving out key parts like, you can't just compare twins screw vs centri because each comes with a different intercooling strategy, which serves to either negate or even reverse any alleged efficiency advantages. Then, you're also pointing out that only under very special circumstances (i.e. like utterly heat soaked back to back to back) data is relevant which it is, but again not the entire story.

If I could summarize it this way. A centri is "TYPICALLY" more efficent when operated in certain parts of it's curve. At high rpms and high pressure differential it starts to become markedly more efficient, but if you're not operating it at high output near the peak of it's efficiency, it's not really more efficient and in some cases, like Mike has demonstrated, it may be operating even lower efficiency than other blower systems. Further, when you throw in the thermal advantages of a liquid based cooling system and heat sink, all the sudden the combination of centri+air-air compared to the twin screw+ air-water, and now the PD setup starts to shine in MOST typical street/strip applications, thus not only eliminating supposed advantages by the centrifugal but actually reversing it to be a liability.

I think if you A) Setup a centri to run at very high blower speed/rpm and high output and B) somehow found the practical space to incorporate an air-water system, the advantage would start to demonstrate itself.

However, here's the rub. Some people do actually overspin the blower and then bleed off the excess with a valve. Let's the blower operate in it's sweet spot. However, the increase in efficiency you just created gets blown out the valve so it's kinda counter productive.

And adding an additional cost and complexity of installing a liquid pump and heat exchanger system starts to negate the simplicity and cost advantage of the centri in the first place.

At the end of the day, just about any of the compressor strategies can be made to work to levels WELL BEYOND what the street type chassis can handle anyway.

There was a time when motor outputs where a debate like this would be more meaningful, but nowadays, virtually ANY blower system is going to be able to produce torque and power well beyond what the factory style chassis can handle. In short, power train output is way out in front of a basically traction limited system.

So these debates about which blower is better are pretty much useless. They all make more sauce than the tires and suspension can effectively put to use ANYWAY. And as those outputs grow, sophisticated systems to hobble and limit the torque output are employed (either through boost controllers or engine management) so it really doesn't matter which setup you choose, on race fuel they can ALL outpace what the car can effectively use without spinning anyway.

On pump gas the debate takes on a little more meaning, because everyone is trying to bump up against the limitations of what BMEP will allow and there this might have utility, but even then we're not talking about HUGE swings either way (meaning the adiabatic efficiencies of one vs the other, WHEN FACTORING IN THEIR INTERCOOLING SYSTEMS is likely to produce similar outputs within a handful of hp of each other).

 

[SnowFox]

According to Paul walker neither Centri or PD is the best. It's infact "NOS..two of the bigs ones" obviously is best.

I can only add dry humor when the topic becomes to complex for me.

I have a Centri and love it. I picked it in part because the install seemed more straight forward, and partly because low-end power was less.

Tons of power and grip down low always seemed to cost me lots of money in repairs "your differential center pin is fused inside, we needed to use the plasma cutter and four tips just to cut it out" *gasp*

 

[cbrtrx]

Yeah who needs lots of engine tq when you have 10 gears of tq multiplication for you. That's why I like centris on 10 speed cars.

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