Gtr Joey's R32 Gtr E-Flex, Twinscroll 83/75 Results

[GTR_JOEY]

Yeaaaaaaa. No! I do that for free apparently haha

[Mick_o]

Hmmmmm can i get myself a stroker built for a carton?

[HarrisRacing]

Do you mind telling me exactly what the setup you had previously was? I'm trying to find solid VE data for the RB engines and I'd like to use dynos (like yours) to determine where we are in terms of VE and turbo calcs and how this is applied. Using the defaults in Match-bot seems to make engines seem more responsive than they are in real life.

For your car and the first dyno posted, I came up with the following numbers so far: I simply can't get match-bot to work with your recorded boost, rpm, and power levels any other way than with these tweaked VE numbers, but they sure are close with these VE numbers! stretching from 72 out to 121 seems outlandish..but it makes the data fit and supports the maximum supported airflow of 68 lbs/min that this turbo is advertised at. I am assuming your engine had cams previously?

RPM - VE

3000 - 72

3500 - 72

4000 - 80

4500 - 100

5000 - 111

5500 - 117

6000 - 120

6500 - 121

7000 - 121

7500 - 118

8000 - 115

I do not know the effect that increasing stroke has on existing VE, but I sure would like to know. I'm hoping it increases at low rpms...because if not, Match-bot doesn't think much changes on the bottom end as far as boost threshold goes with these numbers. If you play with it, you will see that going up from 2.6L to 2.75L makes VERY little difference other than overall power. seems that VE drives a ton turbocharged HP calculations.

Sorry for attacking your thread with technical jargon, but I am trying to help you decide how much power you'll get out of the 8375. Sometimes going UP in displacement hurts efficienies, and resulting power. It may be better matched to a 2.6 or 2.75 than a 2.9

Edited April 12, 2015 by HarrisRacing

[Piggaz]

Joeys build isn't about a lag wagon top end screamer. If it makes peak power at say 6500 and comes back 20 kw or so at 8000 rpm that would pretty much nail it.

[HarrisRacing]

I'm going for a very similar build. I guess I'm trying to figure out what cams and additional stroke do to VE tables for engines and I'm having trouble finding it all.

[r32-25t]

Hate to tell you but experience builds good engine combos not a computer program, there will be so many variables that the computer won't take into account that it will be never be accurate

[zebra]

^^

Unless you are real good at Pipemax or Engine Analyzer Pro

which can be within 1-2% or real world results...If your input data is 100% accurate

[GTRNUR]

Do you mind telling me exactly what the setup you had previously was? I'm trying to find solid VE data for the RB engines and I'd like to use dynos (like yours) to determine where we are in terms of VE and turbo calcs and how this is applied. Using the defaults in Match-bot seems to make engines seem more responsive than they are in real life.

For your car and the first dyno posted, I came up with the following numbers so far: I simply can't get match-bot to work with your recorded boost, rpm, and power levels any other way than with these tweaked VE numbers, but they sure are close with these VE numbers! stretching from 72 out to 121 seems outlandish..but it makes the data fit and supports the maximum supported airflow of 68 lbs/min that this turbo is advertised at. I am assuming your engine had cams previously?

RPM - VE

3000 - 72

3500 - 72

4000 - 80

4500 - 100

5000 - 111

5500 - 117

6000 - 120

6500 - 121

7000 - 121

7500 - 118

8000 - 115

I do not know the effect that increasing stroke has on existing VE, but I sure would like to know. I'm hoping it increases at low rpms...because if not, Match-bot doesn't think much changes on the bottom end as far as boost threshold goes with these numbers. If you play with it, you will see that going up from 2.6L to 2.75L makes VERY little difference other than overall power. seems that VE drives a ton turbocharged HP calculations.

Sorry for attacking your thread with technical jargon, but I am trying to help you decide how much power you'll get out of the 8375. Sometimes going UP in displacement hurts efficienies, and resulting power. It may be better matched to a 2.6 or 2.75 than a 2.9

Regardless of head, cams etc and all things being equal except for displacement, the larger motor will always produce more power everywhere in the curve than the smaller motor.

While a VE at a given RPM point may be lower, remember that VE is effeciency relative to volume being displaced. So while a VE may appear to be lower on the bigger motor for a certain RPM/Load point, it is still moving at least as much air as the smaller motor is for that same RPM/Load point.

Whether the engine is under boost or vacuum, more displacement per cylinder will equal more efficent cylinder filling. For a single rotation the larger motor is moving more gas. Without going into rod ratios or any of that other crap, this means a larger motor will pull more pressure differencial relative to the pressure inside the intake plenum than a smaller motor. If you do factor in rod ratios, the shorter rod ratio has benefits there for better cylinder filling too, due to faster acceleration of the piston away from TDC.

Even at the top end of the RPM range when the head is becoming a restriction to allowable airflow, and the power curve dropping off for the large engine will still be a higher output than a smaller motor would for that same RPM. Simply because it is moving more air through the restrictive ports than the smaller motor can, due to that increased pressure differential.

[HarrisRacing]

Regardless of head, cams etc and all things being equal except for displacement, the larger motor will always produce more power everywhere in the curve than the smaller motor.

While a VE at a given RPM point may be lower, remember that VE is effeciency relative to volume being displaced. So while a VE may appear to be lower on the bigger motor for a certain RPM/Load point, it is still moving at least as much air as the smaller motor is for that same RPM/Load point.

Whether the engine is under boost or vacuum, more displacement per cylinder will equal more efficent cylinder filling. For a single rotation the larger motor is moving more gas. Without going into rod ratios or any of that other crap, this means a larger motor will pull more pressure differencial relative to the pressure inside the intake plenum than a smaller motor. If you do factor in rod ratios, the shorter rod ratio has benefits there for better cylinder filling too, due to faster acceleration of the piston away from TDC.

Even at the top end of the RPM range when the head is becoming a restriction to allowable airflow, and the power curve dropping off for the large engine will still be a higher output than a smaller motor would for that same RPM. Simply because it is moving more air through the restrictive ports than the smaller motor can, due to that increased pressure differential.

Perhaps I was unclear.

Your logic keeps the assumption that the turbo isn't at it's max limit. I was studying match-bot when looking at my stroker and made the realization that these new "billet" wheels are adding airflow on top end and in Joey's case I would absolutely recommend him change the compressor wheel and let me explain why.

His cast wheel 8375 is only rated for 68 lbs/min of airflow. Any more than that and it's horribly inefficient and/or at overspeed (dangerous for turbo) and I'm sure is not recommended by BW engineers.

So using his old 2.6L setup (and some VE numbers I have reverse engineered), the match-bot for top end is as follows:

6000, 21 psi, 58 lbs/min, 542 HP

6500, 21 psi, 63.5 lbs/min, 570 HP

7000, 21 psi, 68 lbs/min, 600 HP (Max flow reached)

7500, 19.5 psi, 68 lbs/min, 592HP (max flow held, dropping boost)

8000, 18.5 psi, 68 lbs/min, 542 HP (boost still dropping to maintain max flow)

8500, 18.5 psi, 66.8 lbs/min, 488 HP

So this, to me, is a GREAT street turbo for a pumpgas 2.6L setup. It's sustaining boost to pretty dang high rpm levels and is just at the edge of the compressor map.

Data here

Now the SAME turbo on his new 2.9L:

6000, 21 psi, 65 lbs/min, 602 HP

6500, 19.5 psi, 68 lbs/min, 607 HP (max flow reached, dropping boost to stay on map)

7000, 17.5 psi, 68 lbs/min, 606 HP (Max flow held, still dropping boost)

7500, 16 psi, 68 lbs/min, 594.5 HP (max flow held, dropping boost)

8000, 14.5 psi, 68 lbs/min, 535 HP (max flow held, dropping boost)

8500, 14.5 psi, 66.8 lbs/min, 482 HP

So here you see that at 8000-8500 rpms the 2.9L is actually making LESS horsepower than the 2.6L at the SAME airflow limitations (turbo limits) This is because the turbo is falling off of the map at overspeed and I have to drop the boost to keep it in the safe zone.

Data here

Now the 61.4mm FMW wheel in his existing turbo on his new 2.9L:

6000, 21 psi, 65 lbs/min, 604 HP

6500, 21 psi, 70.6 lbs/min, 634 HP

7000, 21 psi, 76 lbs/min, 670 HP

7500, 20.5 psi, 78 lbs/min, 678 HP (boost lowered, max flow reached)

8000, 19.5 psi, 79 lbs/min, 622 HP (boost lowered, max flow held)

8500, 19.5 psi, 77 lbs/min, 561 HP (boost sustained, max flow dropped)

This is why I suggested that Joey look into changing out the cast wheel for the FMW 61.4mm compressor and housing that is found in the EFR turbo. This will allow his 2.9L to still be on the map on top end (thus making 30-80 HP more from 6500-8500 rpm over his existing cast 8375) since the FMW wheel limit is 79 lbs/min and loses NOTHING to the 8375 on bottom end with the turbine choices offered (hence why the billet wheels are slowly taking over).

Data here

I hope this helps clear up what I was getting at.

Patrick

PS - I would LOVE to see actual dyno results from this swap Joey!

Edited April 28, 2015 by HarrisRacing

[HarrisRacing]

But I wanted to add...

My math all assumes that the increased stroke (and resultant piston acceleration speed per rpm), doesn't affect the VE table. This was the original question I had and lots of internet searching still didn't provide an answer. So yes, you do get more displacement, which should technically help everywhere, but what if the increased piston speed (vs. standard stroke) reduces VE at high rpms? Then effectively you've almost just moved the power band to the left (good thing really) and let the increased displacement of the stroke help in the bottom and mid rpm range (which again I like on a streetcar), yet lost a little VE at top end (which I agree still should make more HP).

Edited April 29, 2015 by HarrisRacing

[GTR_JOEY]

Interesting, thanks for the post mate, obviously a computer isnt 100% correct but I see what your getting at.

Must remember One of the benefits of the stroker is that I do not need to spin it to 8500 anymore as the power and torque band is now wider and boost comes on earlier. Also cam gears will be dialled in for response so it will actually fall over quicker which is fine as I won't be spinning it much past 7500. Good for reliability

I wasn't aware that its a straight swap for the FMW wheel!??

and a back to back would be great! I'm just sick of spending money is all. I also have the option of going to a larger rear housing which would allow boost levels past 25psi.

But let's see what the final result is, it didn't really fall over too much on the last tune and there is a few things I have done to help improve flow..

Time will tell!

[HarrisRacing]

Interesting, thanks for the post mate, obviously a computer isnt 100% correct but I see what your getting at.

Must remember One of the benefits of the stroker is that I do not need to spin it to 8500 anymore as the power and torque band is now wider and boost comes on earlier. Also cam gears will be dialled in for response so it will actually fall over quicker which is fine as I won't be spinning it much past 7500. Good for reliability

I wasn't aware that its a straight swap for the FMW wheel!??

and a back to back would be great! I'm just sick of spending money is all. I also have the option of going to a larger rear housing which would allow boost levels past 25psi.

But let's see what the final result is, it didn't really fall over too much on the last tune and there is a few things I have done to help improve flow..

Time will tell!

I think it is just the FMW wheel and front compressor cover. I think both of these parts are relatively cheap (likely less than $200 total).

You know (based on our previous conversations here) that I was leaning toward the 8375 cast for my build as well since they are $600 US and they would be a great bottom end pump gas setup for a stroker build. I did go overboard on the 8374 EFR simply because I picked one up for $1700 US shipped and the financials just work after pricing in wastegates, FMW turbo, etc. Bad thing is I'm stuck with the .92 IWG housing now unless they release different IWG A/Rs in the future.

Edited April 29, 2015 by HarrisRacing

[Piggaz]

Why don't you change rear housings? I'm sure somethring could be worked out.

After being in a stock 2.6 with a 8374 1.05 AR rear, I'm not sure if the 0.92 is necessary. Definately not on a stroker IMO.

[HarrisRacing]

Why don't you change rear housings? I'm sure somethring could be worked out.

After being in a stock 2.6 with a 8374 1.05 AR rear, I'm not sure if the 0.92 is necessary. Definately not on a stroker IMO.

Tell us more!! Wait...do more...get us video!!!

[GTR_JOEY]

reaper is the man.. Has v cam as well though

[reaper]

My ears are burning

[HarrisRacing]

Why don't you change rear housings? I'm sure somethring could be worked out.

After being in a stock 2.6 with a 8374 1.05 AR rear, I'm not sure if the 0.92 is necessary. Definately not on a stroker IMO.

I'm going for a similar setup to Joey's...bottom end monster. I like the simplicity of the IWG model instead of 2x external gates, dumps, etc. The excessive "Octopus humping a hair dryer" under the hood just wasn't what I was going for on my car.

[Aggroman]

I'm going for a similar setup to Joey's...bottom end monster. I like the simplicity of the IWG model instead of 2x external gates, dumps, etc. The excessive "Octopus humping a hair dryer" under the hood just wasn't what I was going for on my car.

so really your not going similar setup. Just a stroked bottom end

[HarrisRacing]

so really your not going similar setup. Just a stroked bottom end

I was referring to the small(ish) cams, stroker, smaller AR turbine, etc. Looking for nice street powerband. I would say I'm heading in the right track as opposed to super-high-revving. long-duration-cammed, 2.6L. And I don't like the RB30 block idea with the taller deck, etc with the funky fitment issues.

[GTR_JOEY]

So engine has been in for a couple of months now, a few issues needed addressing such as fuel pumps and making a few other things fit

Everything is hooked up and ready for tuning,

Also fitted the AO rear brembos