Interesting turbo/dyno test tonight= bigger isnt always better

[Otto J]

So Bison and I decided t o do a little playing on the dyno.
We started with his blue street car.
It conists of a stock internal short block with 8 to 1 compression
212 roller cam,stock steel heads with stock valves and some bowl work.
Precision front mount,single nozzle alky control kit,3" downpipe and dual 2.5 exhaust.

ALL TESTS WHERE DONE WITH 27#S OF BOOST 11.0-1 A/F and 21* TIMING.

First test was with a Limit Engineering 61MM P trim turbo with a small garret modified stock ex housing.
This equalled 468RWHP

Second test was with the same turbo and an .83 Housing.
slightly slower spoolup
This test equalled 463 RWHP.

We then swapped a Turbonetics GTK 850 turbo I had here BB with a .63 Precision Housing.
This test equalled 466 RWHP.

This led us to really think about it and we believe that the stock port head with stock valves cannot use the extra air supplied by the larger turbo and the smaller ex housing on the 61mm was not a restriction either.
We ran out of time to throw the 66mm we had on it to ee if this netted the same results but we plan to next week.

I really would like to try the GTK 850 on a car that has a better flowing top end as it obviously has more potential the 466RWHP on a motor better suited for it.

 

[GNBRETT]

Interesting

 

[Otto J]

LOL, this poor car has 54 dyno pulls to 6K rpm on it and still purrs....
and he drives it daily

 

[HighPSI]

hmmm.... How were the inlet temps?

 

[Clark6]

Can't wait for the 66mm results. Man, having your own Dyno has it's advantages doesn't it.

 

[Otto J]

hmmm.... How were the inlet temps?

Funny you ask,actually they where their highest with the GTK turbo,this i am not sure why...

 

[bison]

hmmm.... How were the inlet temps?

Not that good. It actually gained about 5* at its best with the larger compressor. The turbo was good for way more mass flow this engine was using. With the pressure port on the actuator open the engine would only see about 27-28psi. The small ex housing 61 has been over 30psi a few times unintentionally and likely would make 35psi if i wired the gate shut. This engine made over 500whp with better air and more timing. It was surprising to see no gain over what was on there previous. Fwiw this car ran 11.30's with 1.8 60's in 90*+ air the way it was on the 460+hp pulls.

 

[Otto J]

Can't wait for the 66mm results. Man, having your own Dyno has it's advantages doesn't it.

I will be away the next 4 days and can only work 3 days next week as we have the Buick Test day at Cecil County Dragway on sat and I will be tuning on a 10.5 Outlaw car at the Shakedown at Etown on sat-sun next week.

Bison and I plan on testing what ever we can using his car as the the test bed.

I also dyno/tuned Joe Saggiomo's 87 T with Champ Irons and a 71 GTQ and it made 660 through a 2 1/2 inch exhaust at 27#s on Pump Gas
It made 616 on 23#s and we uncorked it at 23#s and gained 6 HP.
I would have figured it would have gained more,but numbers don't lie.

 

[John Wilde]

If I still had my 6265 I would send it to you to try.
I think you have a good candidate there.
Thanks for sharing your experience.

 

[Otto J]

If any vendors want dyno testing done on any products please contact me.
Bison doesnt care how bad we torture his car.

I hope to be doing a back to back test with a TA49 and a TA6265
next week on a champion/iron 212 roller car.

 

[blue-t]

shouldn"t you be unpacking

 

[Otto J]

Packing,not unpacking Paul.

another note,on the results the peak power was at the sam point on all runs at 5150-5200 RPM. The 61 with the small housing showed the best power curve in the tests.I did not expect the the 76MM GTK to be hte best here as it obviously spooled slower.
But it was at peak boost before the peak power point.

also being that the larger turbo requires more air,we actually need to run it with no line on the gate to get the boost to 27#s.
what surprised me a bit was that it only made 359RWHP at 18#s with the larger turbo.

 

[bison]

I will test the 66 turbo on this engine also and probably find the same thing and the same hp. The GTK and the 66 S both have the same ex wheels. The 66 has a Precision .85 ex housing though. It made 413whp on my other car at 13psi. It made 687@24psi. The other engine is actually about 2ci smaller. Im curious to see if the GTK can pick up on the other engine which is a much better test for a comparison to a smaller turbo 76 comp vs 66 comp. I dont think that the GTK with a 3 bolt on it is the correct combo of wheels/housings. It needs a .96 tang 4 bolt to work like the compressor would need to flow the mass flow the compressor could move. Its takes the correct turbo/converter/ compression ratio/cam or you can turn your car into a real turd. All these posts i read about guys making a bunch of power with larger turbos at low boost pressures (sub25psi) is likely a bunch of bullchit and there hasnt been much back to back comparison like this dyno test tonight. The results are very accurate. The timing, a/f ratios, ambient tests and boost pressure were the same and were done within an hour of each other without ever unstrapping the car from the dyno. The boost pressures we used were typical of a street driven car on an aggressive tune. There is no doubt in my mind that if you are building something that you want to haul ass on the street you are better off running a small turbo with a small ex housing and cranking the boost up. This car would be such a turd with the larger wheels that it would have a hard time running in 11's when it ran 11.36@122 with a vacuum launch with the little 61. From what ive seen over the years the p trim turbos with .63 ex housings will take you a long way if you can get the boost up enough.

 

[L8TRH8R]

Subscibed. Great post.

 

[bison]

I also dyno/tuned Joe Saggiomo's 87 T with Champ Irons and a 71 GTQ and it made 660 through a 2 1/2 inch exhaust at 27#s on Pump Gas
It made 616 on 23#s and we uncorked it at 23#s and gained 6 HP.
I would have figured it would have gained more,but numbers don't lie.

I picked up about 10hp when we uncorked my black car on the dyno at around 630hp when i had the 15 year old hooker 2.5" on it. It did spool faster open though. The butt dyno and the real dyno tell different stories

 

[bison]

I hope to be doing a back to back test with a TA49 and a TA6265
next week on a champion/iron 212 roller car.

Id like to get the same 61 on this car to see how it stacks up here.

 

[Otto J]

Id like to get the same 61 on this car to see how it stacks up here.

We would have to speak to the customer.
This would be a lower boost test as we keep his car in the 22-24# range
but for comparison reasons we dont need to push it above that

 

[bison]

We would have to speak to the customer.
This would be a lower boost test as we keep his car in the 22-24# range
but for comparison reasons we dont need to push it above that

I agree. It should make considerably more power at lower boost with those heads. Mass flow will likely still be about the same at 24psi.

 

[Otto J]

I will be making a bung to track back pressure also,would be interesting to see the differences there also

 

[bison]

I will be making a bung to track back pressure also,would be interesting to see the differences there also

we could just drill and tap the plug at my factory O2 location. It has a hex on the outside so it will still be easy to install and remove after drilling through the center. Backpressure will be high on these 3 bolts over 500hp.