karmadhi

I am trying to decide between these 2 turbos, similar price journal bearing. I am trying to find out a dyno comparison over the 2 interested in spool differences.

S400 67mm comp 83mm turbine 950hp

PT6768 67mm comp 68mm turbine 935hp

Is the precision unit overrated power-wise?

ashtons300zx

The spool difference is significant. Your talking a 68mm exducer on the turbine vs an 83mm on the turbine if your referring to the s400sx billet 67mm Didnt think there was an option for a 74mm turbine.

Either way i used the s400 on my built SR20VET and it was pretty laggy and required revving to the moon to give a good fat powerband. Im switching it up to a 6768 billet t4 .81. I was using the 1.10 housing on the BW.

I didnt make full boost until about 6800 rpm and was revving out to 9700 on the dyno, then later raised it to 10,200 and the oil pump didnt like that.

As for my gearing and everything, i dont need to rev past 9700 to trap 165mph on a 24.5" slick so stepping down.

As far as power goes, its not over-rated. If anything under rated as Ive seen dynos topping 935whp on a couple cars using the 6768.

So base it off what your going to be revving to or willing to rev it to to give a nice powerband. My motor is a 2.0L motor 9:1 compression.

Full-Race Geoff

you should have been using a twinscroll divided manifold for the S400SX, thats why performance was off. If you want to use it on an undivided manifold a smaller a/r than 1.10 would be suggested since that the same thing your doing with the .81

karmadhi

Yes you are correct it is infact 83mm turbine wheel, huge. So you used the S400sx 67mm the revised version with the FMW, what housing and flange type?



Do you have any dyno results to see spool ect? I am looking to stay within 9000rpm limit in terms of spool. Would be great to see some dynos of both. I am coming from a s366 BEP T3 turbo, had full boost at 5800rpm.


I was thinking of the crazy idea that later I could add a second smaller turbo and do a compound setup on the BW but as of now I want to run it as is, it looks like its gonna be big for my rpm, I am using a 2l 16v motor, 9:1, 4" exhaust, methanol fuel 50/50 mix.

ashtons300zx

Here is my graph



29psi of boost. Got limited by my wastegate spring. Original intention was to hit around 850-900whp by 40 psi which may have been possible.

Geoff, I know I could have increased the spool time a little bit by using a twin scroll manifold. But not 1000 rpm worth, lol. I went with the 1.10 housing to help out as much as I could and seeing how many honda guys have done the same, using an open scroll manifold on this same turbo I figured why not. I figure with a proper twin scroll maybe would have seen boost 300 rpm sooner. Which still wouldnt have been enough in my picture. It was great and at this power with 15psi in 1st, 20psi in 2nd and 29psi in 3rd and 4th the car went an easy 10.5@150mph with a very bogged launch and baby through 1st gear and into 2nd.

The 6768 will get me where I want to be, making full boost by 5800 and hold power to 9500-9700 or so depending on what I go with. The cams im using help a lot on holding that power. The VE head is pretty efficient as well so the VE of the motor is pretty good in retrospect. Again, just need a smaller turbine wheel. No big deal.

tagperformance

1. You can also improve spool time by increasing your compression ratio to 10.0:1 or higher and also getting a turbo diaper or blanket which can increase the heat in the turbine housing and drastically improve turbo response and your powerband. I also think the borg warner has a better center section when in comes journal bearing durability. If you can get your hands on a billet precision 67mm compressor wheel and have it installed and balanced then you will have a bad *** turbo on ur hands.

ashtons300zx

Yeah, I understand that. There are only two off the shelf CP pistons for the VE, 9:1 and 12.5:1, so yeah wasnt gonna go with a custom piston when the 9:1 will and has done just fine. I was using a turbo blanket as well.

Key is matching the turbo to the setup and what your wanting for a powerband rpm wise. For high revving motors the BW is great. If I could have revved my VE to 11k it would have had a great powerband being at 10,200 it was still holding peak power without a sign of dropoff.

narfdanarf

Actually that's about what a lot of people pick up...800-1000 rpm...even more with a better set of cams.

karmadhi

Is that true, would love to see some dyno results.

Bizarre

This is exactly what happened with my car after a Full-Race divided manifold.

karmadhi

What rpm where you spooling before and what was the change?

Here is a dyno from an evo using the 67-66 PT at 6000rpm he has over 650hp! .82 T3 also, with a divided T4 maybe even better spool?
http://forums.evolutionm.net/evo-dyn...br-6766-a.html



The other dyno is of the S400 67mm fmw just over 340hp at 6000rpm I believe it is a divided T4 1.25AR


New graph hpagt4294jb


Uploaded with ImageShack.us

g-tuned

Considerable difference in spool there! Isnt the 66mm turbine wheel on that precision the new revised thinner wheel?

Boostedld9

Maybe look into a 6466 if your looking for a quicker spool.

ahobbs

I know its not an option, but I can't help but throw it out there. I just finished testing the forced performance 4294hta. I tested the journal bearing and the ball bearing. Didn't notice a diff. The car made right at 950 on the Dyno and I ran a 9.0@159 crashing through the traps. Mph was actually at 170 around the 1000ft before the crash. (logs)


There are more reliable options
Here's a link to the graph.

http://store.forcedperformance.net/m..._Code=Turbo-FP

karmadhi

Is that your actual power graph?

So this is another 67mm compressor, what size is the turbine wheel? What setup did you use (housing and flange type)?

It does seem to have slightly lazier spool to the 6766 but more power up, I am guessing this is using like a 74mm turbine wheel?

Power graph




Uploaded with ImageShack.us

karmadhi

I am just trying to compare all the options and pick the best one for my setup. I am not limited by wheel size or any class rule so I dont want to fall in that category.
I want to get best powerband and peak without having to rev passed 9200rpm on my 2l setup, with goals of a low 8 second setup.

By the looks of it the s400 67mm spools too late for my engine setup, it just seems to be more geared towards higher cc or high rpm engines with its huge 83mm turbine wheel and limited to the 67mm class.

The 6766 precision is making great power and it spools much better than my old s366 (66mm comp 74mm turbine) setup by the looks of it.

The precision 7175 is another turbo I want to get some info on how it behaves on a 2l dohc motor but havent been able to find anything. The new revised precision CEA turbo wheel does it come in other sizes than the 66mm?

I dont see much hype on the new BEP batmo turbos over here LOL.

There are so many options!

ahobbs

What late spool are you seeing? It's 800hp by 7k. It's a 42r wheel t4. So whatever a 42wheel is. If you are talking about mm size on a turbine are you referring to the inducer or exducer of the turbine wheel? Remember they are opposite of a comp wheel. If you are using it for drag racing, which I assume you are, spool means nothing. You will stay in the power band and the diff between having a ball bearing and a journal Bearing turbo is transient time between shifts. With My driving style, I didn't notice a diff and I used both bb and JB. More than anything you get a tried and true Garrett chra and that can not be denied.

Dyno shows loyd of wheel spun btw. Yes that's my Dyno graph.

lugnuts

[QUOTE=karmadhi;48095889]I am just trying to compare all the options and pick the best one for my setup. I am not limited by wheel size or any class rule so I dont want to fall in that category.
I want to get best powerband and peak without having to rev passed 9200rpm on my 2l setup, with goals of a low 8 second setup.

The precision 7175 is another turbo I want to get some info on how it behaves on a 2l dohc motor but havent been able to find anything. [\QUOTE]


I have some info for you. We ran the 6768 T4.96 and a Precision 71GTS(much older version of the 7175) back to back, the 71 re-spooled virtually the same, even with a journal bearing(6768 was BB) the car picked up 3.5 MPH too, back pressure was lower for the same boost. This was a 2.0 liter 9-1 cr on E85, revving to 9100-9200 rpm.

This same 71GTS turbo made 934 whp on a 2.1 liter on alcohol 3 years ago.

When you are looking at the BW turbine wheels, "83mm" is the Inducer (overall diameter) - so 83mm is not "huge". The Exducer on the BW wheel is 74.3 mm, so it is pretty close to the Precision "75" which they measure by the exducer.


Like ahobbs said, in drag racing you can make big turbos work that might not "spool" well on the dyno/street.
The better the driver/shifting is, the better your results will be with larger turbos. The opposite is painfully true as well.

itspools

My s400 67mm makes 40psi by 5400 on my 8.5:1 compression SRT-4. It's still a 2.4. Manifold is a twin scroll one I built and the hotside is a 1.25.

Edit: this was before using co2 and installing the NLR AMS 1000

karmadhi

Ok guys I think I got a few things mixed up here, let me clarify myself.


I can go from my previous setup that I got used to and had good results as far as powerband went and here it goes

S366 cast old turbo full boost 5600-5800 T3 BEP housing
Compressor: 66 mm inducer / 91.4mm exducer
Turbine: 80 mm inducer / 73 mm exducer

S400 67mm FMW
Compressor: FMW 67.7 mm inducer, 91mm exducer
Turbine: 83.5 inducer, 74mm exducer

S400 71,4mm FMW
Compressor: 71.4 mm inducer, 100.8mm exducer
Turbine: 83.5 inducer, 74mm exducer.

PT6766
Compressor: 67mm inducer exducer?
Turbine: inducer ?, exducer 66mm

PT7175 ...


How much lag is there between the S400 67 vs the 71mm?
The BW 67 seems closer spec to the S366 in terms of turbine wheel size.

6766 makes 920 or so whp has a better powerband

BW 67 is a nicer more manly unit to look at will make more power 40-60hp than the precision 6766 at 1500 rpm later.

Someone should give me BW67,71 and pt6766 to try lol.

ahobbs

I think you are worried about numbers too much.

People's cars all breath differently and you are really comparing apples to
Oranges. Your motor may not produce tons of back pressure. Cam profiling and compression beadwork all makes a huge diff in that. Just buy what other have proved and tested to work for your personal power goals.

Once again, power bands need nothing, to an extent and from what I see you won't notice a diff
With what you are doing.

karmadhi

I might just go with a s400sx3 72mm and if it wont spool I might add a smaller turbo in compound setup or zap it with a 50 shot or so. I drive this car on the street sometimes so would be nice to have a broader power band, I guess you cant have it all!

karmadhi

So are precision turbos prone to leaking oil then, thats all I keep reading about!

Full-Race Geoff

I respectfully disagree with everything you just wrote - and i strongly believe a smaller turbine wheel is the *wrong* direction for anything that wants to make serious power

+1

+2

I agree, however most important is using the correct manifold for the turbo...

For motors with proper manifolds, the BW is great.

disagree - ive never seen increased compression spool a turbo faster, and ive not seen a diaper or blanket show drastic improvements in response, it reduces underhood temps (definitely a good thing)

karmadhi

Well I went with PT got a good deal, went for the H ported compressor housing, will be testing the T3 and T4 divided turbine see what will work best for my setup.