Paul Bloomberg

I was checking some hoses around the MAF today and noticed that the little plate on my turbocharger reads- written in with a hand engraver: top line-K26, 2nd-G0600102, 3rd-53269707042M. This turbo replaced a K27#6, I thought it was a K27#8 and I did pick up hp. Could this be some type of hybrid. Do these numbers mean anything to anyone? I am making around 330rwhp, would that be consistant with a K26? Or is could this housing be used to make some type of hybrid? Any input would be greatly appreciated.
Thanks,
Paul

Paul Bloomberg

Just to add a little more info after looking at some other posts. My dynojet chart makes a nice plateau at 4000-6000 rpm@330rwhp. I run 20psi and it will go higher if I put in a smaller jet in the bj bolt and it holds the boost to the redline, even at higher boost levels.
Thanks,
Paul

Danno

Who did you buy your turbo from?

Paul Bloomberg

I'm not concerned about any funny business regarding the turbo or the nationally known shop/person who installed it over a year ago.
When I saw the K26 on the plate. I didn't know what to think. I thought I had a K27(IGNORANCE IS NOT BLISS). I did not know that you could make a K27/hybrid out of a K26. So we live and we learn, hopefully!
Paul B.

Danno

Hmmm, I guess you could take a K26/8 and replace just the compressor side with a K27. So are we assuming that a K26/8 and a K27/8 have the same turbine/hot side?



Hey Paul, what size wheels do you have for those massive 335mm tires on your car anyway? I take it you have a wide-body fender kit back there?

Paul Bloomberg

TOO BIG! The rims are 18/9 and 18/12. The car has a wide body kit. It looks good to me from the side/front, but the view from the rear is ridiculous. If it's a good year I might get the Simmons rims cut down so I can put on 295 or 315's.It's funny the tires still brake loose on asphalt when the boost builds.I can't imagine what some of the stroked and/or bored motors are like with 275's.
Paul
Paul

fletch.

A K27 is much slower to spool up than a K26/6 and K26/8. You may be better off with wht you have.

Paul Bloomberg

Fletch,
The progression went from the stock K26#6 to a K27#6 to a K27#8. I really didn't notice that much of a increase in lag, but I did notice the jump in hp/torque(dynojet)from 280 to 330 at the wheels!. I also had some mild head work done at the same time, so it's not just the turbo making the gain.
Maybe years of riding 2 stroke dirt bikes has programmed me into keeping the car "on the pipe" so that's why I didn't notice the increased lag.
Regards,
Paul

Danno

Well, I think you guys are talking about two different things here; turbo-lag vs. boost-lag. For each turbo, there's a boost-curve of the maximum boost it produces [edit:at full-throttle], kinda like dyno chart like:

• 0psi @ 1000rpm
• 5psi @ 2000rpm
• 10psi @ 3000rpm
• 15psi @ 3500rpm
• etc...

In general, the larger turbos have more boost-lag, which means their maximum boost peak arrives later in the RPM-range. Like a K26 may make 15psi by 3000rpm, but a K27 has to wait until 3500rpm. So the corresponding torque curves also look similar to the boost-curve. Like this comparison between a Turbo and TurboS (both at 15psi @ APE Stg2):


As you can see, the [edit:K26/6] builds boost & torque quicker at low-RPM, but the [edit:K26/8] comes on later, but harder. This is what Fletch is talking about, boost-lag.

However, Paul's been talking about turbo-lag, which is the time it takes for the turbo to build up to its maximum boost when you floor it. Say you're cruising at 60mph in 3rd gear (3000rpm) and you floor it. The max-boost for a K26 at this RPM may be 15psi and K27 is say... 12psi. The turbo lag, then is the time it takes for the turbo to bring manifold pressure from -4psi vacumnn, up to the max-boost level at 3000rpm. In this case, there probably isn't much time difference between the two turbos.

So while the K27 may have a boost-lag disadvantage to the K26, it doesn't have more turbo-lag. Then if you go to a lower-inertia turbo, you may have the best of both.

RIDICULOUS? Paul give us a photo of the rear end (the car's not yours). Most of us are trying to squeeze bigger wheels & tires in, not smaller. If it looks anything like the Lindsey's car, I think that's great!:


Anyway, if you don't like Viper-sized 335mm tires, a 315mm would work on 12" rim just fine (Viper came with 13" rim). BTW, a locked-diff and 20psi tires hook up great!

Paul Bloomberg

Danno,
I kinda get the picture. Thanks for the input. My torque graph looks pretty flat 320@3700rpm-peaking at 348@4500rpm-dropping about about 10 ft. lbs and holding to 5500 or so.
What would be a good example of a lower inertia turbo?
I didn't have a digital pic of the rear end, but it is the same as the Lindsey Racing cars (GT Racing widebody) with 12inch wide rear wheels.
Paul

Danno

Lower inertia turbos have things like ball-bearings and lightweight turbine/compressor blades. Things like titanium axles and Inconel turbines. I think TEC & IHI has things like this, maybe Garrett. The turbo rebuilders like TurboCity would know about all the options available in the industry.

Hey, want to send me a scan of you dyno chart? I'd like to do an overlay and compare it to the stock cars. Thanks - danno

Paul Bloomberg

I don't have a scanner. I will see if I can get the charts I have scanned next week.(stock,K27#6,and the K26, I mean DAH K27#8)
Paul