My thought process here is based on testing probably 50 different turbo combinations on the LNF motor. I have had at least a dozen different turbos and over 1000 dyno pulls on my car alone. A while back, we did some field testing for Borg Warner on a few different efr turbo configurations. In every situation, we saw significant power gains when we switched to a larger compressor wheel, and little to no gain every time we switched to a larger exhaust wheel. We had the same results on Bullseye turbos. When we ran a larger exhaust wheel in the 252 extended tip, it spooled slightly slower and made no more power. When we switched to a 256et with the smaller exhaust wheel, we picked up 30whp and maintained the same spool as the 252et with larger exhaust wheel.

It is also important to remember that we aren't going to have power falling off at 6k rpm with either of the PTE turbos being talked about in this thread. The reality is that either one will make power up to 7400rpm where the lnf is limited in the ecm, anyway. This is yet another reason to choose a slightly smaller exhaust wheel in search of a wider power band.

 

Thats Heavy, lol

 

Of course you will gain power at the same boost level with a larger compressor wheel at the same amount of boost. That's a given.

I was looking at more comparison of the say for example of a 57mm turbo w/ a .48 A/R and a 55mm turbo with a .82 A/R and comparing power bands w/ the same turbine wheel and just change in A/R on turbine. Of course there are other variables that can effect power delivery such as manifold design, exhaust restriction, IC pipes, IC, tune etc....

 

Yes, all of those things are true in a general sense when choosing a turbo for the job. The point that I am trying to make is that the LNF typically leans more towards choosing the smaller exhaust wheel and larger compressor wheel for best results. This is meant that is is more-so than most other engines. Some of this is due to the properties of direct injection, and some is because of the variable cam timing which allows you to oversize the compressor wheel a little more without running into surge issues.

Once again, I'm not trying to argue what you know about turbocharging. I am only saying to lean a little more in the other direction when setting up an LNF.

 

No harm, no foul. Nobody is arguing. Just trading some knowledge.

 

I think the main question for this thread was to go with a 55mm or 58mm inducer compressor wheel
the exducer on both is 76mm, so which one is better for the LNF.....?
My response was the 55 due to the higher pressure ratio on a compressor map, even though CFM flow lower by 4lb/min.........

 

The 5857 has different flow characteristics than the 5557 though. PTE grossly underrates it. Judging by what I've seen there isn't as much difference in spool time as you'd think. Also put it this way as a rough estimate...every 1 lb/min is 10+hp. Maybe someone wants 550 rather than 500. It all depends on the buyers power goals imo.

 

Kind of same subject area...what changes would happen between a 5557 with a .48ar vs a 5557 with a .63ar.

Obviously it would spool quicker and I would assume power would drop off at the top.

 

What I was taught about smaller ars they decrease spool time but hurts top end

 

what do you mean by the lnf is limited to 7400rpm? do you mean even tuned it cannot exceed 7400rpms?

 

Cam phaser are only good to 7400.... Zzp is working on some new phasers for the lnf

 

so anything past 7400 would mess up the cam phasers or just isnt adjustable after that rpm

 

what about this car Matt? its also tuned by you aint it?

http://youtu.be/0NJ6xz-GFzU

 

Man, wish my car pulled that hard with the BNR. lol. i need a bigger turbo now.

 

Daaaaammmmn

 

That is my impression too. But would a .48ar on a PTE 5557 drop off BAD at the top end? Like significantly decrease in power after 6000 rpms?

 

The ECM disables cam phase control above 7400, so the cams go to max lobe separation. This is not good for power. On a ~450whp car, you will lose around 50whp when the cams park. You will also likely experience some knock under those conditions.

I would assume that this is done as a safety precaution to avoid piston to valve contact in the event of shifting to the wrong gear and sustaining 9000 rpm on accident. If the cams maintained an aggressive valve timing, piston to valve clearance would be seriously compromised due to the valve float(bounce) that takes place.

 

Yes, but what are you asking about it?

 

you answered my question with the first post lol I understand just didnt know what you ment not being able to pass 7400 with the ecu. i guess thats why cmillers car on that video threw a code when he launched.....I bet it had knock

 

Regardless of sized turbo, the turbo manifold design, cams, turbine A/R and exhaust diameter will dictate this more than anything.

Smaller turbine arrangements will be very peaky quick in the power band, and suffer torque fall off more than larger turbine A/Rs.

 

You are a fool if you are questioning zzp.

They went 10s on a turbo that flows 49lbs/min...with FWD...enough said.

 

??? I NEVER questioned anyone....all i wanted to know is what he ment by the cam phasers shut down after 7400, I was curious as to what exactly happens and i just threw in the video because i wanted to know if he ment it hurts the engine or if he just ment all valve timing goes to 0....And he answered my question while you sat and ate pop corn......now do i need to explain myself on my thread any more? or do you understand?

 

troll....smh

 

The 5857 is rated to 605hp, but I believe they discontinued it. The 5858 I believe is rated to 620hp. If your goal is 450whp, then you can go with the 5557, which is rated at 535hp.

 

this is true, wouldnt a BNR get where he wants to be with the revised version?