'86 Turbo Dyno ...again
07-31-2007, 02:10 PM
#46
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the 26/6 was/is not efficient in upper rev ranges. that why you see drops of 60+ tq from peak to redline at the same boost pressure. WHen they went to the bigger hotside you gained a little more lag but also a little more efficiency in the upper-end. Thats why 26/8 cars will produce more tq at upper rpm ranges resulting in a larger HP number...
as far as why...the 26/6 is a great turbo for city and hwy driving. lots of low end grunt with minimal lag (as far as turbo 4cyl go). Ran out of breath real fast with the stock wastegate and were maxing out at low psi's with the stock wastegate. The larger turbo (resulting in more air uptop) just made a great car that much better. In reality a stock 26/6 vs a stock 26/8 car will not produce the same boost curve. I believe the 26/8 will have more boost in upper range as well as the efficiency.
as far as why...the 26/6 is a great turbo for city and hwy driving. lots of low end grunt with minimal lag (as far as turbo 4cyl go). Ran out of breath real fast with the stock wastegate and were maxing out at low psi's with the stock wastegate. The larger turbo (resulting in more air uptop) just made a great car that much better. In reality a stock 26/6 vs a stock 26/8 car will not produce the same boost curve. I believe the 26/8 will have more boost in upper range as well as the efficiency.
07-31-2007, 02:31 PM
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jace got it. bigger turbos, even at the same psi, will run cooler than smaller turbos at higher rpm's, netting more power up top.
it has nothing to do with being able to hold boost or not. the k26/6 can easily hold 15psi to redline just like the k26/8. how much power it will make at redline is a different story.
so smokintr6; you're still missing 5psi, start troubleshooting.
it has nothing to do with being able to hold boost or not. the k26/6 can easily hold 15psi to redline just like the k26/8. how much power it will make at redline is a different story.
so smokintr6; you're still missing 5psi, start troubleshooting.
07-31-2007, 02:44 PM
#48
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Nize, A bigger turbo will run cooler, but a K26-8 is not a bigger turbo,... at least not the compressor (the K26 part). A k26-anything with a given amount of exhaust gas flowing through it should run at approximately the same temp.
07-31-2007, 02:49 PM
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Originally Posted by smokintr6
Nize, A bigger turbo will run cooler, but a K26-8 is not a bigger turbo,... at least not the compressor (the K26 part). A k26-anything with a given amount of exhaust gas flowing through it should run at approximately the same temp.
they all add up to net more power at the same psi.
07-31-2007, 03:50 PM
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I'm not going to argue that those points don't have merit... but I will say (and I'm not an expert) that I would be quite surprised to find out that the #6 hotside is the biggest source of restriction in the stock exhaust system, and that changing it would increase overall flow enough to see vastly different temperatures on the compressor side... again, I could be wrong
07-31-2007, 04:01 PM
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Originally Posted by smokintr6
If you can hold 15psi to redline with the stock K26-6, then why the hell would Porsche change to a K26-8, and exchange more lag for nothing? Doesn't make any sense to me. I have personally never seen a stock turbo do that well near the redline... in several cars
So some of these k26/6 that hold 14-16psi to redline are WAYY out of their range so I doubt little if any hp from 5K up is being made; just making heat.
So the #8 holding 16psi to redline might actually make more hp and be a trade off for the lag.
07-31-2007, 04:05 PM
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with lower exhaust backpressure on a turbo motor, the engine's VE gets better, which also increases power. it all adds up.
the bottom line, and the topic of this thread, is that the stock k26/6 can hold 15psi to redline.
some more info on VE;
http://www.epi-eng.com/ET-VolEff.htm
and;
http://www.auto-ware.com/combust_bytes/eng_sci.htm
the bottom line, and the topic of this thread, is that the stock k26/6 can hold 15psi to redline.
some more info on VE;
http://www.epi-eng.com/ET-VolEff.htm
and;
http://www.auto-ware.com/combust_bytes/eng_sci.htm
07-31-2007, 04:09 PM
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Originally Posted by special tool
The 26 is too small for the 951 in all but street car applications - even then its weak.
It makes boost early to satisfy all the magazine readers who are worried about "lag"
Even most of the Porsche tuners make turbo kits to be early spool so they don't "lag"
And if you try to cheat physics - you will get other nasty surprises.
If you want power, you get lag - look at a trans am car, or even a nascar - top end. I guess that's lag.
You guys don't want to know how hard I blow by cars with little turbos - like GT30's - its a joke.
Nothing like a big turbo.
The 951 can spool Heap big turbocharger in time with proper CAMSHAFT TIMING, ignition timing and afr, trust me.
A 7,200 RPM 951 makes similar exhaust gas energy to a 4g63 at 9,000 RPM - something to think about, girls.
It makes boost early to satisfy all the magazine readers who are worried about "lag"
Even most of the Porsche tuners make turbo kits to be early spool so they don't "lag"
And if you try to cheat physics - you will get other nasty surprises.
If you want power, you get lag - look at a trans am car, or even a nascar - top end. I guess that's lag.
You guys don't want to know how hard I blow by cars with little turbos - like GT30's - its a joke.
Nothing like a big turbo.
The 951 can spool Heap big turbocharger in time with proper CAMSHAFT TIMING, ignition timing and afr, trust me.
A 7,200 RPM 951 makes similar exhaust gas energy to a 4g63 at 9,000 RPM - something to think about, girls.
07-31-2007, 04:15 PM
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[QUOTE=tyro]Perhaps some of you recall I dynoed my then stock '86 turbo last fall:
I then pulled the engine for a reseal. I added chips, gutted cat/3" catback, rebuilt the K26/6, wrapped the crossover, TiAL 38mm w/ LBC, 5-angle valve job, 3.0 bar FPR and a Fidanza flywheel.
Check out the AFRs. Way too rich, right? Why? Need more boost, different maps? I'm not much of a tuner.
I don't think correction was added for either run - now/then, and the temps were higher today by 30 degrees. On a cool day, I can get full boost by 2800RPM with the TiAL as indicated by the car's tach and an autometer gauge.
[QUOTE=tyro]
So this was done on a Mustang? If so, add about 10% to compare to dyno jet results that others have posted.
Otherwise your comparing apples to oranges.
I then pulled the engine for a reseal. I added chips, gutted cat/3" catback, rebuilt the K26/6, wrapped the crossover, TiAL 38mm w/ LBC, 5-angle valve job, 3.0 bar FPR and a Fidanza flywheel.
Check out the AFRs. Way too rich, right? Why? Need more boost, different maps? I'm not much of a tuner.
I don't think correction was added for either run - now/then, and the temps were higher today by 30 degrees. On a cool day, I can get full boost by 2800RPM with the TiAL as indicated by the car's tach and an autometer gauge.
[QUOTE=tyro]
So this was done on a Mustang? If so, add about 10% to compare to dyno jet results that others have posted.
Otherwise your comparing apples to oranges.
07-31-2007, 04:26 PM
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Originally Posted by smokintr6
I'm not going to argue that those points don't have merit... but I will say (and I'm not an expert) that I would be quite surprised to find out that the #6 hotside is the biggest source of restriction in the stock exhaust system, and that changing it would increase overall flow enough to see vastly different temperatures on the compressor side... again, I could be wrong
As to making heat (after the intercooler) take a look at my video again (from 1:19 to 1:34): http://www.youtube.com/watch?v=m_UAb6QOknU
But then again, who am I to argue against strong beliefs.
Laust
07-31-2007, 04:42 PM
#56
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Originally Posted by toddk911
So this was done on a Mustang? If so, add about 10% to compare to dyno jet results that others have posted.
Otherwise your comparing apples to oranges.
Otherwise your comparing apples to oranges.
One run was done in the fall - as stock. Temps were in the 50s.
The most recent run was done this past Saturday, and it was 90 in the shop.
Either way, both runs were done on the very same dyno.
Blue=new, green=old:
07-31-2007, 05:34 PM
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Laust,
Very informative. How stupid was I to think that products like the Lindsey 270 WHP kit actually work? It seemed so simple, just improve exhaust flow after the turbo, keep the tired wastegate shut a little longer, and add fuel. I didn't realize that all the restriction in the exhaust system was at the turbo. You should call Dave and tell him what you found. He'll have a hard time arguing with your calculations.
PS I wasn't saying that the bigger hot housing wouldn't help.. I'm just saying that there is a lot more going than just that housing. And I still don't believe that a K26-6 will hold 15 psi to the redline.
In fact, If anyone has an early turbo having only modified chips and boost controler, that can PROOVE that their turbo is a K26-6 (AKA recipt for installation work, or recipt for part and they installed it, or they are the original owner). I will pay for ONE dyno pull in columbus Ohio to prove their claim if 15 psi to the redline. They pick up the tab if it doesn't perform.
Very informative. How stupid was I to think that products like the Lindsey 270 WHP kit actually work? It seemed so simple, just improve exhaust flow after the turbo, keep the tired wastegate shut a little longer, and add fuel. I didn't realize that all the restriction in the exhaust system was at the turbo. You should call Dave and tell him what you found. He'll have a hard time arguing with your calculations.
PS I wasn't saying that the bigger hot housing wouldn't help.. I'm just saying that there is a lot more going than just that housing. And I still don't believe that a K26-6 will hold 15 psi to the redline.
In fact, If anyone has an early turbo having only modified chips and boost controler, that can PROOVE that their turbo is a K26-6 (AKA recipt for installation work, or recipt for part and they installed it, or they are the original owner). I will pay for ONE dyno pull in columbus Ohio to prove their claim if 15 psi to the redline. They pick up the tab if it doesn't perform.
07-31-2007, 06:32 PM
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smokintr6: are you arguing that on our cars a um modded 26/6 cant hold 15psi EVER? or that a stock car with chips and boost controler cant hold 15psi? I can guarantee you that a stock wastegate will NOT allow you to touch 15psi at redline. But like others and I are saying, with a Tial (like tyro has) he should and will be able to hit 15psi at redline as long as he has no boost leaks.
I have already posted my dyno w/boost and that was done with LR MAF, MAfterburner, Tial 38, BLack ****, and B&B exhaust. There are many people on here pushing 15+psi on 26/6's.
Before adding my Tial I was hitting mid 12psi on stock wastegate with a shim at redline. Tial allowed me to hold up to 16.5psi at redline (turbo MAXXED), but I kept it at 15psi max.
I have already posted my dyno w/boost and that was done with LR MAF, MAfterburner, Tial 38, BLack ****, and B&B exhaust. There are many people on here pushing 15+psi on 26/6's.
Before adding my Tial I was hitting mid 12psi on stock wastegate with a shim at redline. Tial allowed me to hold up to 16.5psi at redline (turbo MAXXED), but I kept it at 15psi max.