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More Huge Thanks to SSA - new 6766 results...

8.1K views 114 replies 40 participants last post by  grandporschegt  
#1 ·
So I'm a bit of a turbo whore lately, and I'm trying to ring the last drop out of my stock motor. I recently upgraded from my DBB 6765 .84 divided to a DBB 6766 1.15... and the results frankly are a little bit shocking. The results are below.

I apologize for the photo - the printer was down, was the best I could do ;)

Other changes to the system.

1. Moved the BoV as close to the TB as possible (it was on the hot side in the passenger vent hole like most)
2. Replaced my TB coupler with a wiggins style clamp because I kept pushing that pipe into the fans and it had caused a hole in the radiator
3. 2PSI bump in max boost (36 to 38)
4. 1 degree of timing increase (1 degree produced over 20hp gain) - we could have gone more but as i state below, we're already pushing it on the stock internals.

I will admit that it's possible we fixed a boost leak, however I was holding 36psi to an 8000 rpm redline with the 6765, so I find that a bit unlikely...

The REAL gain came from drastically reducing back pressure - on the 6765 with smaller AR, at 36 psi I was at 56 psi of back pressure, on the 6766 with 1.15 I was at 38psi of boost and 46 psi of back pressure - there is no doubt I could have made 40-45 psi of boost with this turbo and setup, but frankly we're already flirting dangerously with the stock rods limits, and while I am planning on building a motor - I wasn't prepared to send a rod through the block last night on the dyno.

Net gain was over 100hp and 79 ft/lb of torque..

Thanks again to SSA for their expert guidance in turbo selection, they took a bit of a gamble on this one, they knew I wanted to make over 800 on the stock setup before building my motor and insisted that freeing up back pressure was the key, I was very worried that the 1.15 would be laggier and slower even with the newer more efficient 66 wheel, both Precision and SSA assured me it wouldn't be and they were both right.

I take back everything negative I've ever said about the 67s, because at this point I'm a solid 200 hp beyond what I adamantly felt liek they were capable of about a year ago.

Solid line is the new 6766, dotted line is the 6765, both were DBB turbos, and both are divided setups, on full-race header, dual tial gates, recircd into 4" dp/mp, and hks Ti 4".

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#2 ·
oh, I will also add that at this point we have maxed out my fuel system lines, I am running a -8 into dual -6s to the rail, at 38psi we begin to see fuel pressure NOT keeping up with boost. Base pressure is 43.5, at 30 psi we were right at 73.5 psi of FP, at 38 we were starting to see drop off and were only making 75.5 psi of FP. Still with in the tolerance level for proEFI to correct but not optimal to be sure. I'll be replacing the -8 with a -10 feed and splitting it into at least two -8s I may just run -10s the whole way on the feed side.
 
#3 ·
I would have never expected to see a 67mm turbo make over 800whp, and it is spooling faster then the 6765, I am very impressed.
 
#4 · (Edited)
honestly when I saw the dynos side by side, I was shocked... I think the results are a tiny bit inflated because of the temperature last night, it was in the 50s when we dynod, BUT when we dyno'd the 6765 right before the mile it was in the 70s, and my logs show AIT's with in 10 degrees of each other so perhaps not. at 15psi the car made 520whp, which was 30 more than the 6765 (spring pressure), and spool was similarly quicker even at that pressure. I would have expected the 6766 with the same AR to be faster, but never would I have guessed that with a 1.15 it would STILL Be faster, sorta messes up everything I thought I knew ;P

Edit: this is the dialed down number too - once we discovered the FP dropping we decided to back off a little, we were initially going to throw some e98 in the car, run 40psi and ramp the timing up a bit... We "settled" at 38psi with only a single degree of advance. I have no doubt I could make 850-900 on this turbo with some good rods and pistons... and it'd be an absolutely street raping machine.
 
#9 ·
Ha, congratulations on the new results man!

Wanted to chime in here as a recent ProEFI/PTE 6_66 convert myself. Your experience and sentiment sounds very similar to mine during the recent build regarding playing the "guess what it made NOW" game - Larry would call and tell me' "guess what it made at Xpsi." I would gues, he would add 100whp to whatever I guessed, and then we'd exchange "wtf's?", and sit there going :scratch:

Lol.

Glad you're happy with your new setup bro. I'm thinking seriously of coming down to run the mile with you next spring.


Craig
 
#10 ·
what cams/intake/ic are you running?
 
#13 · (Edited)
Those are crazy numbers. 38psi is a lot of boost on a stock motor. You are brave my friend.
How u gained 300rpm spool going from 84a/r to 1.15a/r I dont know. Maybe the cooler weather gave the spoolup gain but in hotter weather that would mean you spooled the same. Absolutely amazing.

Is there another graph posted I am getting 2 red X's on the screen.


What happens after 7K rpm? Does the power die off or stay flat?

I might have missed it but what fuel is this on?

Any chance of hitting a dynojet?
 
#16 ·
We only ran to 7000, redline on car was set at 7500 - the ONLY time the car ever sees higher than that is at the mile events. However it seemed to be staying flat. The weather I think is negligible - It was only 20 degree different, if it were 50-60 degrees i'd think it'd be a bigger deal - but in addition to that, my AIT's, the actual temperature of the ingested air was only 10 degrees diferent, and by the end of the pull they were nearly identical.

is anyone else NOT seeing the graph?

I'm on e85, according to my ethanol sensor I was at 86% ethanol last night. I concur with you on the spool - I can't explain why I picked up 300+ rpm of spool on what I would consider a gigantic change in AR, I fully expected to LOSE 500 rpm and move my power band more to the right, that's not what happen at all - I picked up power across the entire range and more than 100 hp at peak while still increasing the power band.

just to clarify both pulls were the same gear correct?
Yes, fair question - all my dyno tuning and dyno pulls are in 4th, unless we're trying to specifically tune for weird part throttle issues. To be clear the previous turbo and power got my car to 201.7 at the mile.

That is a fantastic powerband!

Ian
Thanks... I haven't really felt it on the street yet because it's frankly a bit silly...the car is an absolute monster.
 
#14 ·
just to clarify both pulls were the same gear correct?
 
#17 ·
I've found frequently that, at times when reducing backpressure, allows more air/fuel charge into the motor. When this happens you physically have more exhaust energy. Now why this happened somewhat on a base percentage across the entire RPM band, is probably an amalgamation of factors including a 20 degree change in temp, perhaps removal of a boost leak, and more exhaust effiency on that 66 wheel.
 
#18 ·
agreed - I have detailed logs of all the pulls, just haven't had time to go truly anlyze them compared to other logs, even at RPMs from vacuum the car was making more power. I want to reiterate that while it was cooler it wasn't like it was 110 degree heat vs 55 degree - it was just below 70 degrees on the 6765 and 52 degrees last night - both sessions were done at similar times, about 6:30pm, and my logs show the actual AIT variance was even less, 10 degrees at the start of the pull and less than 1 degree at the end of the pull.

I would point out those numbers are NOT weather corrected, so the variance may be less significant, however the butt dyno tells a whole new story, including some brown skid marks - the new turbo makes the car damn near unstreetable with my normal PS2s on - where as the 6765 I could easily control it... I Realize that's totally annecdotal, but I beat my car up nearly every time I drive it and the raw feeling of power delivery is significantly different - and literally scared me which is a first in a very a long time.

Also, I believe that I could have significantly reduced boost, and increased timing and made similar or better results, we spent a ton of time tuning the 6765 and optimizing the timing curve for it's power delivery, last night we spent maybe an hour on the dyno making sure the boost curve was controlled, and then turned to timing, where a single degree picked up 20+ hp in the mid range. That tells me there is a lot more power to be made in timing.

Because my plans include building a high compress 3L we didn't truly optimize the tune last night, as my goal was to be over 800hp and we did that with ease. I'll spend the money on the dyno after the built motor and run this thing at 40+ psi ;)
 
#26 ·
awesome #'s Zach and props to Chris D. for his excellent tuning ProEFI skills. I can't wait to get the full potential on my set-up!!! He'll have his hands on my car soon!
 
#27 ·
He did a great job with my car too...props to ss and Chris!!
 
#30 ·
Nice results! Thanks for sharing, makes me think about my own plans for sure. I have a non-billet 6765 currently with a .81 non-divided housing but since I have a Greddy divided manifold I am strongly looking at the new 6766 with a divided housing... I was looking at the 1.00 and hadn't considered the 1.15. Probably running pump gas primarily unless I can find a way to get E85 more readily available in my area.
 
#34 ·
If you are running pump gas dont expect to get numbers like this. The E85 fuel is the biggest factor I personally think in these high dyno numbers. SP's own test showed 33rwhp difference in E85 vs pump and that was only on 19psi. Im sure the gains are more with higher boost. I want to pull the trigger but dont think I am yet not until I see some C16 numbers or something. Plus 38psi is tooo much especially if you dont have E85 at your local gas station.

Dre99gsx im glad you chimed in. I know you have been considering the switch also maybe someone local can lend you their unit...haha