Installing a SMALLER turbo...

This is an informal poll.

For years the trend was to buy a larger turbo for more power.
Now a days you see many owners buying SMALLER turbos for less lag.

Depending on the model, many experience little or no power loss if their old turbo was a journal type bearing and the new smaller turbo is a double row BB.

How many of you out there wish you had faster spool up even if it did mean a loss of power?

How many have PLANS for a smaller, faster turbo?

What do you think the ideal size is? 6766? 6466? 71mm plus?

And how many are perfectly happy with their 71mm and larger turbos?

First, I have tested and proved that there is virtually no spool difference between a journal and BB turbo.... 70 rpm is the most that I measured and at high rpm the journal actually spooled and recovered faster.

Secondly, with the advent of E85 spool has substantially been helped! How much HP are we talking about? Does anyone really need more than 800 RWHP? The 6466 is the perfect turbo for that!

Originally Posted by Sound Performance

Secondly, with the advent of E85 spool has substantially been helped! How much HP are we talking about? Does anyone really need more than 800 RWHP? The 6466 is the perfect turbo for that!

Will the 6466 make 800WHP without E85 or meth?

Sure on race gas!

Originally Posted by Sound Performance

Sure on race gas!

Anybody tested that? Do you have any links?

Originally Posted by dragosid

Anybody tested that? Do you have any links?

Google 6466. Evo w/800 popped right up.
Bdave - DRIVE your car and decide for yourself!

I'm planning to swap my current 6776s for a 6766 or 6466. Since 110 octane race gas is unavailable here in China and my car is DD, thus I'm definitely in for a quicker spool turbo.

Originally Posted by Sound Performance

First, I have tested and proved that there is virtually no spool difference between a journal and BB turbo.... 70 rpm is the most that I measured and at high rpm the journal actually spooled and recovered faster.

Secondly, with the advent of E85 spool has substantially been helped! How much HP are we talking about? Does anyone really need more than 800 RWHP? The 6466 is the perfect turbo for that!

But, how effective is your QSV? I see only a torque graph on your webpage:



How much power...and how much sooner can I expect spool or boost to come in other just running just a turbo and ex. mani.? Will this be effective with turbos smaller such as the 6766 or 7168 that I am focused on.. I ask because I am stuck at these two very different turbos. Don't get me wrong, I see all that insanely nice torque curve in addition, but for the street and some light drag - Im hopeful of getting the best of both worlds these days with technology and more products being made for the e46..

I just picked up a spare block and crank for my build at the moment and will be running pump (93), pump and meth at most occasions. E85 is hard to find in North Jersey right now and I get worried about actual ethanol content year round to purchase a 55gal drum. Race Gas.. is a big possibility now.

Quicker spooling (smaller) turbo also causes a much larger and earlier torque spike. Much more harsh on engine internals and also harder on drivetrain. In addition, much more chance of detonation, harder to control, and **** can go boom much quicker. On a stock high compression motor, not the best idea to go "smaller." There's a reason HPF chose the turbo's they did, they provide a much more linear and safer powerband while yielding numbers that make customers happy.

On another note, I have an old school journal bearing Precision 74 and love it. Get **** for it all the time since it's not being ran to its optimal range. I've also had one MLS head gasket and put 3x the miles on my car than a few of my buddies cars I've built on their 2nd or 3rd MLS's. Only difference, their cars running 61-62mm turbo's resulting in the same mid 500 whp figures on more boost because of the smaller turbo's. I also have quite possibly the worst rear end/subframe design ever, even worse than the E46, and have managed to keep the completely stock rear end intact for 40k miles with boost, 500whp+. Most people rip welds and diffs out of my car with stock 240hp motors. Later spool, much easier on everything. Know how to drive, the powers always there, you just gotta know where to find it

Originally Posted by Dreikraft

Google 6466. Evo w/800 popped right up.
Bdave - DRIVE your car and decide for yourself!

Oh, I expect to be quite happy with E85 and a slew of other mods that should really help my spool. I think the only thing that I might have changed was making my motor higher compression. I can always do that down the road IF I feel like it. Not loosing any sleep over it, for sure. Under no circumstances will I be changing out turbos.

No, I asked the question because its a current topic and I am really interested in what others are experiencing. I dont always post threads that directly pertain to my build.

I am very surprised to hear SP say there is not much difference between a journal bearing and double row ball bearing. I was lead to believe the difference is substantial. There is a significant cost premium for DRBB too.
I feel justified for having purchased my turbo in DRBB.

While we are on the subject...Nope. I have no regrets at all about my choices. I would have opted for the AEM infinity if that had been a choice. Even that, I have no immediate plans to upgrade. I just cant justify the cost right now. On a NEW build from scratch, of course. Uh uh. I am not changing a thing. My builder did INSIST on upgrading to a riveted feramic disc. I got a stupid low price and NO labor fee on the upgrade, so I cant complain. It got installed today.

I would LOVE to have the AEM Infinity. Just not at the price they are talking about. Maybe in a year's time if there is some super special running.... In the mean time I dont intend to feel deprived because I am not running it. Not at all.

I am finding the responses to this thread most interesting as I hope others do as well.(especially advocates for less aggressive spooling, not that I agree with that necessarily.). Keep the information flowing!

Originally Posted by A4RingedONE8T

I've also had one MLS head gasket and put 3x the miles on my car than a few of my buddies cars I've built on their 2nd or 3rd MLS's. Only difference, their cars running 61-62mm turbo's resulting in the same mid 500 whp figures on more boost because of the smaller turbo's.

Forged>cut ring>peanut butter>mls

Originally Posted by Dreikraft

Forged>cut ring>peanut butter>mls

If it's not abusing the head gasket it's abusing the next weakest link. The S54 doesn't share head gasket problems from boost like the S52 does however the same strain is going somewhere else, I was just using it as an example. I'd much rather replace a $300 gasket in 5 or 6 hours than a set of rod bearings or rings, or worse yet a whole bottom end

I am very surprised to hear SP say there is not much difference between a journal bearing and double row ball bearing. I was lead to believe the difference is substantial. There is a significant cost premium for DRBB too.
I feel justified for having purchased my turbo in DRBB.

There is a difference in transient response (lag). There is not much of a difference in boost threshold.

Originally Posted by SPDu4ea

There is a difference in transient response (lag). There is not much of a difference in boost threshold.

There is a small difference in transient response or recovery which is different than initial lag. Testing on a supra at 3000 or lower the BB had better (a few tenths of a second) transient response. At 4000 they were about equal and at 5000 and above the journal was actually faster than the BB.

every one is talking about E85 and meth injection...im new to FI. what is the difference in an E85 set up. i know water/meth injection cools the air substantially allowing more air to be packed into a cylinder.

I would not mind hearing the science behind the faster spool up with E85. I know the whole Stoich thing is different too. The readings for lean/rich are totally different with E85 than gasoline.
I am not quite sure how or why that factors in.

Larry will know. He seems to be the "go to" guy lately on the forum. When Larry from SP speaks, People listen. LOL. I know I do. Great guy too. He has answered several of my questions(about clutches, manifolds etc) via email which is really great of him. I thought I would give him a well deserved shout out. HPF Chris too...to be fair. These guys take time out of their busy day and give personal attention to members which is really incredible when you think about it.
We are lucky to have such a supportive family who share knowledge, not hoard it.

I will simplify this.... E85 burns cooler and resists detonation. You can run a LOT more timing (10+ degrees) with E85 therefore you are making more horsepower EVERYWHERE. Thus with more horsepower you have more exhaust energy, more exhaust energy spools the turbo faster. Plus you are always burning 30% for fuel with E85 which contributes to additional exhaust energy.


Make sense?

You say when I speak people listen.... this obviously does not apply to my wife!

Thanks for the compliments though, I really appreciate them!

Lar

Originally Posted by Bdave

I would not mind hearing the science behind the faster spool up with E85. I know the whole Stoich thing is different too. The readings for lean/rich are totally different with E85 than gasoline.
I am not quite sure how or why that factors in.

Larry will know. He seems to be the "go to" guy lately on the forum. When Larry from SP speaks, People listen. LOL. I know I do. Great guy too. He has answered several of my questions(about clutches, manifolds etc) via email which is really great of him. I thought I would give him a well deserved shout out. HPF Chris too...to be fair. These guys take time out of their busy day and give personal attention to members which is really incredible when you think about it.
We are lucky to have such a supportive family who share knowledge, not hoard it.

DRIVE your car!

ITT: First time I have ever heard anyone call an HPF power band linear.