We had five different single turbo FD's on the same dyno, same day, same tuner (Steve Kan) last weekend here in Florida. Besides my GT4082, there was an Apexi RX6, 60-1, T04e and GT40R. I would have liked a few more turbos in the mix but the results are interesting none the less. The GT40R's results were less than spectacular, not due to the turbo, but to a substandard engine with low compression.



The 40R did produce boost sooner than the 4082 and I'm sure it would have continued that way had the engine been healthy. My own engine, while not injured, is less than perfect. Apparently the mixture of Atkins apex seals with their smaller corner seals, and used rotor housings in good condition are not a good mix. It allows for compression blowby in a nutshell, something that's audible to those in the know such as Rolo and Jesus Padilla who were in attendance (and Steve too). Undoubtedly, I'd produce stronger numbers with better spool with a fresh, well built engine and new housings. My exhaust manifold primaries are quite large as well, larger than the current GReddy T78 manifold. Smaller primaries will waste less energy through expansion and help with spool as well. There's always something, right? Split was kept at 14 degrees. There's probably another 10hp messing around with split. One thing to note is the dramatic increase in midrange torque. I compared a dyno run I did a while back where I tuned with Steve's session. At one point I'm making about 60hp more in the midrange. Crazy. Car is much faster than before and a beast between 4 and 8K. Notice my power doesn't fall off past 7K like everyone else. This is due to the lower intake manifold being ported. I only did about the last 5" and it took me an hour to do. A good mod.



I've labeled each turbo next to it's peak hp reading number at the top. Steve tunes for 11:1 a/f ratio.



It's no wonder people say the RX6 is a great street turbo. I don't start to surpass it until after 4K rpm. All turbo numbers are within 2psi. I believe the 60-1 maxed out at 14psi while everyone else was around 16. No dyno graph for the T04e as I left before I could get a printout of that tuning session. I believe it maxed out at 330rwhp due to boost controller issues.



Anyway, enjoy and observations welcome.

 

I'm going to make that dyno graph a bit bigger for everyone...

 

Here's the difference between me tuning my own car and Steve tuning it. Although I did not spend any time on my midrange like Steve did, I'm sure he would kick my butt regardless. They're on different dynos but I believe the numbers are relevant. Each are the uncorrected numbers. I now believe the Clayton is reading high, which makes my results even more impressive.



RPM Me Steve Difference

3K 80 72 -8

3.5K 117 109 -8

4K 174 160 -12

4.5K 215 240 +25

5K 230 280 +50

5.5K 280 322 +42

6K 309 365 +56

6.5K 340 379 +39

7K 380 390 +10

7.5K 391 390 -1

8K 401 394 -7



Different dynos, different days. Definitely hotter when Steve was tuning. I plan on hitting the Clayton again soon to see how much of a difference there is. I have a feeling there's about a 8-10hp difference between the two which would negate any of the lower readings from Steve's tuning.

 

Here's the GT40R vs. the 4082. One question I do have is whether the 40R is the larger 88mm wheel? Looking at the inducers, the two turbos look identical with the compressor covers on. Naturally, Russ' numbers with the 40R would be MUCH better with a healthy engine.

 

My best run, uncorrected numbers.

 

That's pretty dissapointing on the GT40R. How bad was his compression?

You'rs is verry impressive! ...only 200rpm's later then the BB 40R.

Nobody had the new R85?

 

michel my rx6 was running 14psi and i hit better numbers than that actually. i got 351.8whp and i believe it was about 299.6 torque. not suure on the torque number but it was above 296 and below 300. i am sure about the whp number though because harrison wont shutup about him beating my car by one horsepower! steve said i would have been able to hit about 370 whp but i was having some injector breakup and i didnt want to push my luck anymore that day.

 

LOL, we'll have to put the smackdown on Harrison



I believe your higher numbers were the uncorrected numbers. It's strange as it was fairly hot that day. If anything, I'd think the corrected numbers would be higher, not lower.

 

I don't want to say too much about the 40R until we find out why it was loosing compression. It was pretty bad though. Enough that it would make a huge difference in the final dyno numbers.

 

Michel, I think it sucks for you to have done all that work only to get shot down by some old housings and some corner seals. Thanks for sharing your dyno sheets. I only get more excited for a r85 with each post.