250/200s sooner than later.....

Power Hungry · Apr 30, 2012

farm boy said:
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 · Apr 30, 2012

ToMang07 said:
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 · Apr 30, 2012

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..

MadDiesel73 · Apr 30, 2012

Yes He did

TrailerHauler · Apr 30, 2012

TARM said:
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.

JAP · Apr 30, 2012

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

Jason?

Lowdown89 · Apr 30, 2012

Groomzybanshee said:
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 · Apr 30, 2012

JAP said:
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 · May 1, 2012

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 · May 1, 2012

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.

MadDiesel73 · May 1, 2012

That's a good point. Bill have you seen any turbo surge or stall/bark with the 1.0 in Jason's truck?

WIESEL · May 1, 2012

Lowdown89 said:
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..

Power Hungry · May 1, 2012

MadDiesel73 said:
That's a good point. Bill have you seen any turbo surge or stall/bark with the 1.0 in Jason's truck?

No, I didn't. Truck pulls great and not the first hint of surge at all.

Lowdown89 · May 1, 2012

WIESEL said:
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..

Your welcome, that's the whole reason why I have tried to make sure everything we do is posted up so everyone can see what works and what dosen't.... I'm not finished with the truck yet, still have the gears to install along with the transmission that bill is gonna do, I also have a sump, fluidampr, new fan and some fancy mishimoto radiator hoses lol that I will prob do after I get the truck back from Bill not that it's gonna add any real performance haha just wanna clean it up under the hood as much as possible

TyCorr · May 1, 2012

Bill, as for.the effects of the bmw has on a 38r, could the reason for the loss in overall performance have to do with the fact that the 38r is EXTREMELY efficient right off the shelf? Its optimized for what we do with it. I personally feel that many of the jb turbos(bw s-series mostly) are seeing such huge improvements because they are leaving so much on the table to begin with with the cast wheels. There may be a reason in that fact.

The 38r is awesome on a stock truck, a stock truck with a chip, a stocker with a fuel system, and an upgraded set of stg IIs are nice with it. I cant wait to.experience it with some hybrids.

Gearhead · May 1, 2012

average said:
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.

It's a shame that the thing didn't come with a bigger exhaust wheel. That would take care of most of the percieved problems with this turbo. You could also use the wastegate at part throttle to dump some extra drive presure just like the factory intended and have the same effect. At the end of the day the 1.15 doesn't make much difference up top because the wheel itself is the restriction. If you drilled the divider and used the wastegate you can have more power everywhere when compared to the 1.15 since you can drop the drive pressure that you can't do with the non wastegated 1.15. I have seen a whopping 6hp gain on a truck with cam and heads that makes extra drive pressure when compared to stock components when swapping to a 1.15 housing.

Power Hungry · May 1, 2012

For reference, I did cross drill the divider in the turbo housing and noticed no gain up top. It may make a difference on the street as far as surge control, but I never really noticed any surge anyway.

JAP · May 1, 2012

Gearhead said:
It's a shame that the thing didn't come with a bigger exhaust wheel. That would take care of most of the percieved problems with this turbo. You could also use the wastegate at part throttle to dump some extra drive presure just like the factory intended and have the same effect. At the end of the day the 1.15 doesn't make much difference up top because the wheel itself is the restriction. If you drilled the divider and used the wastegate you can have more power everywhere when compared to the 1.15 since you can drop the drive pressure that you can't do with the non wastegated 1.15. I have seen a whopping 6hp gain on a truck with cam and heads that makes extra drive pressure when compared to stock components when swapping to a 1.15 housing.

:whs: And while it its on a dyno, now would be the best time to see.

TARM · May 1, 2012

Matt,

Basically we want the specs of some of those "pull off" Garrett turbos, as tend to have the comp wheel size of a 38R but the turbine wheel of the 40 or 42 series depending on which one. Issue of course is they are setup in standard not reverse so we end up being at a T4 mount and then there are many choices.