Garrett 38R 1.0 vs 1.15 dyno test

Power Hungry

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Moderator Note: This was originally part of another thread that was kinda of buried in a conversation that hit upon several topics. I felt it was worthwhile enough information to merit a separate thread in the event others want to discusss it further of find this information later

Tom S





Hey all. Sorry for the delay. I need to take some time yesterday to go through all the configurations and datalog every run to make sure that I am providing the most accurate information I possibly can. I appreciate everyone's patience while we took time to review and process this information and hope that everyone finds it to be useful. Now, on to the good stuff.

First, the question was asked about the part number for the exhaust housing. That number is 70213-0005 which is a true 38R 1.15 A/R housing. With that out of the way, let's move on to the testing.

In case it has been overlooked, the test vehicle used is as follows:

Ford F350 Super Duty CC DRW, A/T with 4.10 gears
Engine rebuilt in May of 2011 - .030 overbore, new Mahle pistons, forged rods, stock camshaft
Injectors - Full Force Diesel 250cc/200% Single Shot
Turbocharger - GPT38R w/1.00 A/R Wastegated Housing
HPOP - DieselSite Adrenaline
Fuel System - DieselSite CPR w/Walbro fuel pump, regulated at 70 PSI
Exhaust - 4" Downpipe back

All dyno runs are performed locked in 3rd gear with the torque converter locked to provide a 1:1 ratio through the transmission with no slippage or shifting concerns. Also, the engine speed is stabilized at 1400 RPM before starting each run so that spooling characteristics can be accurately compared.

All our original runs and datalogs were produced with the standard GTP38R turbo with the 1.0 A/R Wastegated Housing. Our best run (on 04/18) produced 566 HP and 1189 Ft./Lbs. TQ after correcting the fuel pump problem we had where pressure dropped to 25-28 PSI during the run. Even with the pressure dropping we were still in the 540's at around 1140 Ft./Lbs. TQ range. For a stock 38R I though this was rather impressive, especially when the truck starts and drives like a factory 7.3L truck, at least until you stuff the accelerator to the floor. Here are some notable points from this configuration:

Dyno Run - 04/17/2012 - GTP38R, 1.0 W/G housing, Stock compressor wheel
(All values rated at 3500 RPM)
  • Max Boost - 34 PSI
  • Max EBP - 47 PSI
  • Max EGT - 1300
  • Peak HP - 566 @ 2613 RPM
  • Peak TQ - 1189 @ 2512 RPM

On 04/22 we performed a pre-run to establish a base to take into account current weather conditions. Ambient temp and humidity were relatively similar to the prior runs when we installed the Walbro fuel pump, and as expected the base runs were within 5 HP and 10 Ft./Lbs. TQ of the original runs on 04/18. We removed the turbo, changed the exhaust housing to the 1.15 A/R housing and installed the BatMoWheel (BMW). Several runs into the new configuration we immediately observed a sharp drop in performance. Boost was down, EGTs were up, and HP & TQ were down. Notable points from this configuration:

Dyno Run - 04/17/2012 - GTP38R, 1.15 Non-W/G housing, BMW compressor wheel
(All values rated at 3500 RPM)
  • Max Boost - 31 PSI
  • Max EBP - 44 PSI
  • Max EGT - 1400
  • Peak HP - 522 @ 2621 RPM
  • Peak TQ - 1058 @ 2593 RPM
  • Net HP Loss - 44 HP
  • Net TQ Loss - 131 Ft./Lbs.

On 04/28 we performed an initial base run to verify that the current power output matched the last run we did the previous week. HP and TQ curves were comparable. We removed the turbo and re-installed the 1.0 W/G housing, leaving the BMW in place. Subsequent runs indicated that while there was a 3 PSI increase in exhaust backpressure, there was no appreciable increase in boost and power did not improve. In fact, the dyno runs from switching to the 1.0 housing were nearly identical to the 1.15 housing. Notable points from this configuration:

Dyno Run - 04/17/2012 - GTP38R, 1.00 W/G housing, BMW compressor wheel
(All values rated at 3500 RPM)
  • Max Boost - 31 PSI
  • Max EBP - 47 PSI
  • Max EGT - 1400
  • Peak HP - 525 @ 2689 RPM
  • Peak TQ - 1055 @ 2575 RPM
  • Net HP Loss - 41 HP
  • Net TQ Loss - 134 Ft./Lbs.

After letting the engine cool down, we again removed the turbo, re-installed the factory 38R compressor wheel, re-installed the 1.15 non-W/G housing, and then performed a series of runs. There was an immediate improvement in lower RPM spooling along with an improvement in overall performance. Notable points from this configuration:

Dyno Run - 04/17/2012 - GTP38R, 1.15 Non-W/G housing, Stock compressor wheel
(All values rated at 3500 RPM)
  • Max Boost - 34 PSI
  • Max EBP - 45 PSI
  • Max EGT - 1300
  • Peak HP - 542 @ 2620 RPM
  • Peak TQ - 1141 @ 2433 RPM
  • Net HP Loss - 24 HP
  • Net TQ Loss - 48 Ft./Lbs.

At this point, we've removed both the 1.15 A/R housing and BMW and reinstalled the original 38R components. Power is back up to 561 HP and 1178 Ft./Lbs. TQ and boost is still at 34 PSI. The 2-3 PSI drop in EBP from running the 1.15 housing does not justify the expense of the housing, especially since the stock 1.0 housing produced 20 more HP, 45 more Ft./Lbs., and spooled more quickly than the 1.15 housing.

This is the final comparison between the stock 38R compressor wheel and the BMW with both the 1.0 and 1.15 housing. Please note that the HP scale is on the RIGHT side of the graph and the TORQUE scale is on the left side.

(click on image to enlarge)
jason_seay_bmw_test_sm.jpg


Our overall impression is that in this configuration neither the BMW nor the 1.15 housing performed as well as we had expected. The drop in drive pressure from the 1.15 housing, while causing a noticeable drop in peak performance, didn't have as significant of an adverse an effect on spooling characteristics and low RPM power. However, our testing and observations indicate that the BMW suffered significant losses in both peak performance and spooling characteristics, with extremely noticeable lag, higher EGTs, and more smoke throughout the RPM range.


Now for the disclaimer: I strongly urge everyone to please keep in mind that while the turbo modifications didn't offer any improvement in this configuration, it doesn't mean that there aren't applications where the modifications would offer some benefit. These are simply our observations made on a single vehicle with specific modifications and tested in a controlled, consistent environment. We offer this information as a general reference, and while we make every effort to provide accurate and unbiased data, we do not accept any responsibility for how the data we have provided is interpreted or misinterpreted. Other individuals may chose to perform their own tests and draw their own conclusions. If any manufacturers would like to receive copies of any of the dyno or datalog information we have produced from our test procedures, or if there are any questions about the test procedures themselves, we will be happy to provide that information upon request. If you are not a manufacturer, please do not request any further data outside of what has been posted in this thread.

I hope this information is helpful and informative.
 
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MadDiesel73

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Well this confirms what my pro sotp meter has been telling me. Looks like I'll be calling bullseye turbo in the morning.... Thanks bill for your professional analysis of all the configurations. This is super informative and pretty much puts to bed one of the most common mod discussions for the old 7.3. Matt @ Gearhead has told me a few times theres not to much point going to the 1.15. And this proves that with numbers and graphs in a controled test like we havnt seen yet but desperately needed. Great work bill.
 

Aaron S

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Very cool tests and thanks for performing them for our benifit.

Ive got a question about the egts. With the horsepower your making id imagine your running the injectors to there max, as in not detuned at all. The egt seems incredibly low for that amount of fuel, is it just the fact that it is a quick dyno run? I know its been talked about in the past that larger nozzles will produce higher horsepower with lower temps so it kinda makes sense. The next question is, what kind of temps do you see on the road under a full throttle run?

Thanks for the info again.

Aaron
 

farm boy

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Thanks for all the great testing info.

Whats hard to understand, is the fact that these 2 runs had the same max boost psi, only 2 ebp psi difference, and the same max egt's, but yet a 24hp loss. I would love to hear everyone's theory on why the loss of Hp & Tq.

Thanks again for all the time put into this.

Dyno Run - 04/17/2012 - GTP38R, 1.0 W/G housing, Stock compressor wheel
(All values rated at 3500 RPM)

Max Boost - 34 PSI
Max EBP - 47 PSI
Max EGT - 1300
Peak HP - 566 @ 2613 RPM
Peak TQ - 1189 @ 2512 RPM


Dyno Run - 04/17/2012 - GTP38R, 1.15 Non-W/G housing, Stock compressor wheel
(All values rated at 3500 RPM)

Max Boost - 34 PSI
Max EBP - 45 PSI
Max EGT - 1300
Peak HP - 542 @ 2620 RPM
Peak TQ - 1141 @ 2433 RPM
Net HP Loss - 24 HP
Net TQ Loss - 48 Ft./Lbs.
 

MadDiesel73

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I think it might have something to do with spool times. I'm just guessing but my thought is the faster it spools the sooner it makes power the more rotational volocity and other (air volocity) the more power is pushed so to say.. I dunno just a guess.. School me
 

TARM

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I wonder if where everyone sees the benefits for the 1.15 is going from a non waste-gated 1.0. That would explain why some get a noticeable benefit and then others do not. Add in differences in tuning and parts.
 

ToMang07

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I wonder if where everyone sees the benefits for the 1.15 is going from a non waste-gated 1.0. That would explain why some get a noticeable benefit and then others do not. Add in differences in tuning and parts.

Is there a non-wastegated 38r? Or are you just saying in general?
 

Power Hungry

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Thanks for all the great testing info.

Whats hard to understand, is the fact that these 2 runs had the same max boost psi, only 2 ebp psi difference, and the same max egt's, but yet a 24hp loss. I would love to hear everyone's theory on why the loss of Hp & Tq.

Thanks again for all the time put into this.

Honestly, I'm rather curious as to the reason for this myself. I'd have expected to see some loss of boost to coincide with the change in EBP, but really didn't see it. I know there's a big consideration in regards to the spooling characteristics and how that carried into the power curve, but once spooled it really shouldn't make all that much difference. Keep in mind that I am using a mechanical boost gauge to measure the boost and it's only as accurate as my videos of the gauges and what I see when I'm running the truck. I *could* be a pound off here or there but still think the data we've seen is still quite accurate. The overall thing is the dyno plots and they unequivocally show that the configuration we ran suffered a significant performance loss.

I'm still cruising through the datalogs and processing the information to see if there is anything else that may explain the difference in power output, but as of yet I have no reasonable explanation. All I can say is that when we put the 38R back together, the power curve returned. If anyone has any interesting theories, I'd love to discuss them.

Take care.
 

TARM

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Is there a non-wastegated 38r? Or are you just saying in general?

Yeh I could have put that a lot better. In general I guess is the best way to say it. What I was thinking is most never adjust the WG properly or have it set to be shut much the way many do with the stockers.





Bill,


Did you try to make any fueling adjustments when you had the 1.15 on there and the stock wheel to see if you could squeeze any more out of it or what it just left as it was for the original setup.
 

Groomzybanshee

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Matt Robinson has said the 38r will make more power with the 1.0 housing for the past 3 years.. At least I think it was him..
 

TrailerHauler

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Bill,


Did you try to make any fueling adjustments when you had the 1.15 on there and the stock wheel to see if you could squeeze any more out of it or what it just left as it was for the original setup.

I know this wasn't directed towards me, but I believe if you look back over the last couple pages Bill was saying he altered a few things to try and get back that peak HP number they hit first.
 

Lowdown89

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Matt Robinson has said the 38r will make more power with the 1.0 housing for the past 3 years.. At least I think it was him..

I have seen other folks say that,then I have seen just as many people say that the 1.15 housing should have come stock on the 38r because of how well it runs.... Seeing as how there seems to be such a variation in the way these trucks run even with the same combos it seems that testing it out first hand is the only real way of knowing for sure..... But then again that's just the thinking of a simple minded redneck like me lol
 

Lowdown89

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Time to cut and drill that 1.0 housing and see what happens...

Jason?


Lol that's bill's doing... He is the one who has my truck lol... I would like to see how it does with it but I'm not gonna ask bill to pull the housing off again I think 4 times is enough for now, maybe in the future Unless I figure out how to win the lotto then I doubt I will still be messing with the 38r haha
 

TARM

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Is it me or does the HP peak look a bit low in the RPM band? OR this a case of the effects of using a load dyno vs inertia? With 200% nozzles I would have thought we would see HP peak into the 3K range

Is it possible that the WG was able to bleed off enough BP while there still being plenty of exhaust energy to extend the peaks not only higher but further up in RPM? You can see they run almost linear to each other but where the 1.15 stops I can only assume the ability of the WG allows the 1.0 housing to keep a more positive boost : BP ratio until it peaks a 142 RPM and 24 HP higher.

You would think with the dif in TW peaks that this would play out in HP peak as well even to a bit of a greater extent but this could be because maybe they are both by that RPM reached the point where efficiency is declining. Point being the added benefit of the WG is great than the top end gains of the larger ratio housing alone.
 

average

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Interesting numbers! My old SOTP meter didn't notice a huge performance when I went to the 1.15 but the EGT drop alone was worth it for me, along with not having to hear that flutter sound whenever I got on it good. Sucks that I might have lost 20 or so hp doing so.
 

WIESEL

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Lol that's bill's doing... He is the one who has my truck lol... I would like to see how it does with it but I'm not gonna ask bill to pull the housing off again I think 4 times is enough for now, maybe in the future Unless I figure out how to win the lotto then I doubt I will still be messing with the 38r haha

Maybe we can get enough guys to throw down and get that done. I would throw in a lil $$ to see numbers, I am goin with a similar injector setup with my 38r and will be putting my stock housing on, after seeing these results.

Thanks for posting all this, been a good read..
 

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