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Went to the dyno with my new build. Engine is a REW, large street port self designed, s4 scalloped rotors, E30 fuel (mostly pump 93), SXE369 with 1.0ar, Turblown EWG cast manifold, full 4” exhust, Aem Infinity, at 17psi timing went from around 7 to 9 at redline and full boost hapend at 4,100 rpm (has happend as low as 3,850rpm when the weather was 40 deg cooler). Power is going through a 4 speed dog box, 3.5” drive shaft, and a 8.8 rearend. Dyno pull is at 17psi, electric fan kicked on at 5,200 and robbed a little power. Once the engine breaks in a little more I will shoot for 700whp.
Thanks. No boost creep what so ever, boost held solid 16.9-17.1. I will have to dig for the exhaust port pics, they are some old housings I ported 9 years ago (edit: found some). The port opened way eairly, and closed way late...the good engine I have for the car will have the same intake ports but the exhaust ports will not be as big.
Great result, the sustained torque at revs on an extend with the 80mm turbine gives me confidence in the direction I want to head. Do you think your upper manifold is having a significant impact?
Is the rear end a Samburg setup or you did it youself, I think I would like to go 8.8 with something similar to my current 4.77 gears as the osg ratios i have a pretty close to the first 5 in a t56 magnum. A reasonable cruising gear and gearbox/diff that won't explode using semislicks or drag radials and AI/alcohol boost would be nice.
Slides, am not sure what exactly gave it the tq past 7200 but I am thinking the intake has something to do with it. I also have a low temp thermostat (It was heat soked alittle @ 168 f for this dyno pull normally its 155ish) afr was 10.9-11 and intake temps only had a 2 deg rise. The only thing port wise that I did diffrent than my other builds was I scribe the side seal trace and ported all the way to it for the intake port. I did the samberg 8.8 but I was a little un happy with the weld in fittment, I made a set of lasers that I put on the pinon flange and trans output to align everything and then used washers that fit tight on the bolts that I welded in place on all the diff mounting points to keep it from shifting and miss aligning. No vibration at all, i put in 1” of miss alignment in the driveshft so maybe 1.x degree to keep the ujoints happy. The samberg kit came with some verry loose fitting (horable quallity) axle bars, however after showing him in pics and videos of how bad the splines where he contacted the manufacturer and sent me a set from a new batch that where aceptable. I do like the clearance the samberg kit gives, overall I am happy even though it wasnt a (just weld in) affair.
Thanks strokercharged, yea I was scared that it was going to be a 4,800-5,000 turbo but over all I am pretty happy. The 69 is definitely a little slower with transiant throttle than the 66 but should still give me a responsive powerband once I rev it higher. Not sure how it will act at autox around here, I will be in first gear only for one of the tracks so It might hit to hard and blow the tires off.
nice going and lots to like on your setup. i love a combo of gas which has the needed lubricity to help our rotor housing surfaces and alcohol which provides cooling and octane. E30 would be so much better than E85 as you get the benefits of alcohol with reduced wear V E85. i run gas as base fuel and 900 to 1500 CC of meth as AI so i am close to you as to gas alcohol ratio but only in boost.
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i have an excel file of 76 dyno runs, all single turbo corrected to SAE. i have power at 6 rpm points. 5500 thru 7500 and then a total for the 6 numbers.
i also have used the data points to calculate the apportionment of power between the plot points. here's how you compare to the average:
as you can see your setup starts to shine around 7000. obviously there are a number of factors such as the fact you have a 740 rotary rwhp turbo.
the SXE 69 and SXE 66 share the same exducer diameter but the 66 has a significantly smaller inducer area and therefore trim (51 V 57). i am attracted to the 66 as it offers big power BUT has a major midrange advantage
with the smaller inducer. the 57 trim 69 is a top end assassin.
i am currently evaluating my EFR9180 which has the same compressor wheel as yours however you have a better overall output due to the later style uprated compressor cover. once finished with my 9180 i am going to do a
SXE 66 as i want to evaluate the midrange V the 69.
looking at the picture of your engine bay (hotside close to LIM & air intake downstream from heat exchangers) i suggest you take a quick read of my mica heat barrier suggestion found here: SYSTEM DESIGN
you mention IAT only rose 2 degrees... i remember looking at a Power FC log of mine from a dyno run and seeing nothing but 27s (that'd be C of course) for the run. of course that's ridiculous so i decided to actually learn what was going on and switched to a thermocouple similar to how we measure EGTs. Accuracy is is a quarter of a second and +/- .4 tenths of one percent error over the entire range.
Here's a log... IAT goes from 70 to 120 F. around 21 psi with my 9180. note the IAT (third plot) rise stops dead in it's tracks and declines when the methanol starts which is the bottom plot.
This IAT reduction is another advantage of running all gas as base fuel and getting your alcohol thru AI. by injecting it a foot or so upstream of the throttle body the charge air is cooled by almost 100 F. considering compressed air coming out of the turbo is above 300 F, and therefore less rich in oxygen per volume, IAT reduction is money. every degree drop in IAT adds oxygen to the flow. more oxygen, more power.
Last edited by Howard Coleman; 02-23-19 at 04:07 PM.
Damn, the exhaust ports are big as I suspected when I saw the high rpm torque.
I hate how little power under 2,000rpm my engines with big exhaust port had though. You notice that every time you pull out from a stop or crossing streets in the city.
Guess I just need to try 4.77 rear gear next time I do ported build.
Blue TII, I have a first gear that will do 66mph in first gear so its hard to tell how mu h tq I am missing.
Howard, I am in the process of controling the heat as that is one thing that I dont like about this setup is the proximity of the turbo to the LIM. The filter does have multiple fresh air paths and the intercooler is fully boxed in and is the largest I could posibly fit. At this boost level the air temp comping out of the turbo should have been in the 250-260 range. (My 550whp repu sees a 50-70 deg rise during a 4th pull, however its intercooler is a fraction of the size)
I use 0 smothing so I can see misfires, there are zero misfires as I have a m&w cdi and have used this dyno for thosands of pulls so I am familiar with the read out. Mostlikley it was from small bits of spinning as the tires are old and the car is very light coupled with the fact the alignment is off as I just did a quick eyeball alignment based off the front wheels. Most of the time this is just from tires, if it was more dramatic it would indicate a misfire or detonation or just bad tires.
At first i was wondering how the hell is that car 2200 lbs, but i see its stripped out and no cage. Should be an awesome autox and street car, you usually see a much smaller turbo for autox FDs.
Nice results! I will point out that you left 100 ftlbs of torque on the table from 3500-5000 rpms by running the SXE instead of the EFR. Please understand I am not being negative just pointing that out to those lurking trying to understand the price difference between the two BW turbos.
Nice results! I will point out that you left 100 ftlbs of torque on the table from 3500-5000 rpms by running the SXE instead of the EFR. Please understand I am not being negative just pointing that out to those lurking trying to understand the price difference between the two BW turbos.
I get that the lighter exhaust wheel should reduce spool/lag, but will it change the boost threshold? If not the dyno sheet is going to look pretty similar between the two if done in fourth gear.
Originally Posted by djsevenNice results! I will point out that you left 100 ftlbs of torque on the table from 3500-5000 rpms by running the SXE instead of the EFR. Please understand I am not being negative just pointing that out to those lurking trying to understand the price difference between the two BW turbos.
I get that the lighter exhaust wheel should reduce spool/lag, but will it change the boost threshold? If not the dyno sheet is going to look pretty similar between the two if done in fourth gear
If you were on a loading dyno like Dyno Dynamics and had the RPM locked so dyno load kept increasing holding the engine to that RPM then the SXE with the same compressor would make the same boost and torque as the EFR equivalent.
On a Dynojet torque is measured by how long it takes to accelerate the mass of the big concrete filled drum. This simulates actual load on the engine from accelerating the vehicle weight.
Usually Dynojet turbo spool for our cars (vehicle mass close to the weight the drum mass was trying to simulate) really close to what you will see on the road.
For a 6-8,000lb Diesel truck the Dynojet drum mass isn't nearly enough and you have to brake boost it or get the optional dyno brake to get up to full boost.
So EFR 9180 at ~17psi hits full boost on streets/Dynojet ~ 3,500rpm instead of 4,000rpm like your SXE.
That does equate to over 100ftlbs torque at 3,500rpm- and gets the wastegate open sooner as well which sets you toward the upswell of torque you see after peak boost.
So the SXE doesn't catch up on torque right when it manages full boost, it catches up once it gets its wastegate flowing and that is going to be closer to 5,000rpm.
So, the light EFR exhaust wheel allows you to hit peak boost faster and allows more wastegate flow since the it takes less exhaust energy to accelerate the lighter exhaust wheel which also raises engine VE.
Here is a Dynojet graph of EFR 9180 at 14.5psi boost. You can re-scale the peak torque to match yours to make up for it possibly being an optimistic dyno or whatever- its the shape of the torque curve you want to look at since all Dynojets have the same drum mass the car has to accelerate.
My experience on how ports affect torque curve is from running the same T04B 60-1 on huge street port with big exhaust like yours versus small street port with just slightly earlier opening exhaust.
The big port motor made less torque under peak boost, but torque ramped up crazy fast as the turbo spooled to full boost.
The small port motor made quite a bit more torque under 2,000rpm and torque ramped up more gradually as the turbo spooled up to full boost.
Same turbo spool per engine rpm on both ports except near redline where the big street port caused boost to start to creep as the turbo oversped.
So the SXE doesn't catch up on torque right when it manages full boost, it catches up once it gets its wastegate flowing and that is going to be closer to 5,000rpm.
I think I agree with most of what you've said above but I'm a bit confused by this statement. I understand what you're getting at regarding the wastegate and drive pressure, but have you seen any hard data on that? I assumed that the difference in torque would be mainly due to porting.
I get that the lighter exhaust wheel should reduce spool/lag, but will it change the boost threshold? If not the dyno sheet is going to look pretty similar between the two if done in fourth gear.
The torque curve will not look similar on a dyno or feel the same while driving the car. Until you experience the EFR few understand its greatness with the rotary. Unfortunately when the EFRs were released when you google searched them for dyno comparison it always showed the link to Supra Forums where they compared a precision 6266 to EFR8374(going off memory here) and there was little to no advantage. However, on a rotary the EFR is an absolute game changer for power under the curve and low end response. OP is shooting for 700HP so I believe he made the right choice, I was simply pointing out for the average owner the difference an EFR makes. It really is like comparing Sequential to Non-Sequential twins on a bolt on FD. Both accomplish similar results from 5000 rpms and up but its a much more pleasurable driving experience to start the power band 1000-1500 rpms sooner.
The torque curve will not look similar on a dyno or feel the same while driving the car. Until you experience the EFR few understand its greatness with the rotary. Unfortunately when the EFRs were released when you google searched them for dyno comparison it always showed the link to Supra Forums where they compared a precision 6266 to EFR8374(going off memory here) and there was little to no advantage. However, on a rotary the EFR is an absolute game changer for power under the curve and low end response. OP is shooting for 700HP so I believe he made the right choice, I was simply pointing out for the average owner the difference an EFR makes. It really is like comparing Sequential to Non-Sequential twins on a bolt on FD. Both accomplish similar results from 5000 rpms and up but its a much more pleasurable driving experience to start the power band 1000-1500 rpms sooner.
I guess as BLUE TII mentioned above, the shape of the torque curve will depend on the ramp rate. I'm only familiar with Dyno Dynamics which allow you to set the ramp rate manually. Kevin mentioned that he made full boost at 4000rpm here and that looks similar to other EFR9180 dynos I've seen, so in this case there seems to be plenty of time for either turbo to get up to speed. Therefore, I believe that both graphs would look roughly the same.
Of course I agree that the EFR would have less lag on the road, but perhaps for Kevin's application that wasn't a big deal.
BTW BLUE TII, the dyno sheet you posted above seems to be for an EFR8374?
So the SXE doesn't catch up on torque right when it manages full boost, it catches up once it gets its wastegate flowing and that is going to be closer to 5,000rpm.
I think I agree with most of what you've said above but I'm a bit confused by this statement. I understand what you're getting at regarding the wastegate and drive pressure, but have you seen any hard data on that? I assumed that the difference in torque would be mainly due to porting.
On my EFR 7670 with divided manifold and dual 44mm MVR wastegates I ran the turbo without the wastegate boost reference line (no wastegates) and with.
Without wastegates the torque peaks with boost and then boost and torque plummet. You make much more torque with the wastegates open because in order for air to go into the engine exhaust must exit.
mrselfdestruct1994
BTW BLUE TII, the dyno sheet you posted above seems to be for an EFR8374?
That is a big oops!
This one is slightly more relevant. S4 TII streetport though and with 35% Ethanol.
On my EFR 7670 with divided manifold and dual 44mm MVR wastegates I ran the turbo without the wastegate boost reference line (no wastegates) and with.
Without wastegates the torque peaks with boost and then boost and torque plummet. You make much more torque with the wastegates open because in order for air to go into the engine exhaust must exit.
Thanks for sharing that, very interesting. Was the maximum boost limited by the wastegates being forced open, or was the turbine in stall?
Assuming the latter, do you think the effect you saw could be specific to a turbo that was simply too small to achieve the desired boost level?
If the turbine is already maxed out your wastegate is no longer limiting turbine speed, it's just relieving exhaust manifold pressure, which wouldn't be the case with a larger turbine.
I pulled that directly out of my *** so could well be wrong... Just thinking out loud. Interested to hear everyone's thoughts on this as I haven't seen any discussion on it before.
The wastegates stayed shut with no boost reference.
I think engine VE plummets due to high exhaust manifold pressure which lowers the exhaust output to drive the turbo proportionally.
I had the same thing happen on my old T04B 60-1 with 60mm wastegate. It had boost creep with the wastegate working, but if I disconnected the wastegate the engine couldn't even make full boost. On the 60-1 I actually physically deleted the wastegate with a block off plate. Seems counter intuitive.
02-23-19, 12:09 AM
Nice results! I will point out that you left 100 ftlbs of torque on the table from 3500-5000 rpms by running the SXE instead of the EFR. Please understand I am not being negative just pointing that out to those lurking trying to understand the price difference between the two BW turbos.
Interested to hear everyone's thoughts on this as I haven't seen any discussion on it before.