As the title says.

there are a lot of people here who know a lot about turbo's.

So I was thinking could we come to a general consensus on the best turbo for a 2.5 ltr stock internals 951. What hot housing, wheel style everything is the best compromise of little lag and efficiency say to 18 psi of boost?

Is there a magic bullet?

What do the masses think?

 

Wondering the same. I'd like to make a turbo and injector upgrade (while updating my chips) to make some good HP.

Maybe a K27/6? One of the LR turbos? Vitesse??

 

I am not really looking for brands.

I want to know the spec of the turbo. Housing size, Wheels, all the nitty gritty. I know there are guys on here who know this stuff. Cost isn't really an issue for me either just the best for the money you pay.

Dave, Chris, Vick, John you guys know who you are. Share the knowledge.

 

There is no magic bullet.... Here's some turbo's I've either installed or driven in a 2.5L 951.

I have a Vitesse stage 2 and love it. I did a back to back drive of my car and a similarly equipped Tial GT30 car and liked it a lot but stillthought the Stage 2 had the overall edge. The owner of the GT 30 car liked his set-up a bit better (for good reason).

My experience with a super 75 with a #10 hotside is that it's terrible for a street car but is probably okay for a big track.

A Vitesse stage 3 was also nice but I'll never gain enough full use of the top end power to justify the loss in spool over the stage 2 but still a better choice over the super 75 for the street.

A GT25 spools fast but lacks punch and requires a lot of boost to make 400 HP and lacked the pull I was looking for (technodyne car).

I believe a 27/8 is a bit too laggy and a 27/6 chokes off a bit much upwards of 18psi but I like the spool.

So it's really about taste and what your looking for. Many owners are going to give you the same experience with the turbo they selected but fewer will be able to offer the actual experience of multiple turbo's (cost prohibitive).

Also, if you think John, Dave, Tim or anyone else will tell you why someone else's turbo is better, you'll be disappointed. You'll either have to make an informed decision based on you needs (boost, spool, efficiency), customer's feedback, or comfort level with a vendor. Compressor maps can only tell you so much......

 

How would you put a 26/8 in this comparison, S Stock turbo?

 

Mark, before anyone can answer your question, you must define what your requirements are. Spoolup, HP target, transient response, boost characteristics, street, track or both, do you want to be able to modulate the boost?, do you want the engine to feel like a V8?... Many variables to deal with, and there is not one single turbo to 100% meet each requirement.

It's easy to configure:
- a turbo to make huge power with a narrow power band (lag!) or
- a fast spooling turbo that will drop off up top.

Coming up with a turbo that spools up quickly, yet is capable of supporting lots of HP is more complicated (which I like). But will make the 951 much more enjoyable to drive and much faster.
Designing a turbo with a broad power band (large area under the curve) will always make your car a faster car.

As a example, I recently had a customer that for undisclosed reasons wanted to keep the factory look. We built him a cheater turbo that looks identical (on the outside) to a K26/8. While still using the factory CV and KLR chip, a modified DME chip and a restrictor in the banjo bolt we got 14psi max, then boost dropped to 11psi by 4200-4400rpm. Torque was a healthy 340+ and power was around 280 at the rear wheel. With a dedicated boost controller and a steady 15-17psi, the number would have been much better. This configuration was exactly what the customer required.

In my opinion, when buying a off the shelf turbo, there will always be compromises. Getting a turbo to match your requirements as close as possible, will always yields better results and in the long run you will enjoy it more.

As far as sharing the actual components used in a successful turbo configuration, whoever got it right will not disclose it (for the obvious reasons). Each person you ask will give you a different opinion.

I personally recommend buying a turbo based on what performance it provides, this is teh bottom line. Who cares if it's A or B, as long as it performs and meets your requirements. This is where a track record and feedback from actual similar turbo owners comes into play.

Having said all of that, I'm afraid the 951 market is about to have less turbo choices as some of the components may be NLA (at least that's the word from the main suppliers).

 

"Having said all of that, I'm afraid the 951 market is about to have less turbo choices as some of the components may be NLA (at least that's the word from the main suppliers). "

Please do expand on this John!!

 

I have a Garrett GT30R double ball bearing turbo with a 0.63 A/R ratio and love it. I have also had a stock K26/6, LR Super 75/8. The GT30R spools much, much faster than the LR75 and provides slightly more HP at 16 psi boost. Peak TQ also comes on later in the rpm curve and boost doesn't falloff at redline. For some reson, my LR75 started falling off at 6k rpms.

If you want a good turbo for the street, the GT30R is a good choice.

 

+1

PITA installation....... but damn good =)

True GT30R = great track turbo

 

The LR Super 75 is a big turbo. We only carry one bigger. It's for someone who wants to make a lot of HP and/or running a larger displacement engine that can push it into boost quicker. If your expecting to be able to compare that to anything, compare it to a GT35 since it has the exact same compressor
wheel in it. Depending on the turbine and housing your using, will determine more of what happens then the cold side changes will.

"For some reson, my LR75 started falling off at 6k rpms."

Don't know what was wrong with your set-up for that results, because set-up right, that won't happen. Impossible! Especially comparing to a GT30. It's a larger GT wheel, and the turbine is larger as yours is smaller then a Stage 3. Our 75's have had a Stage 5 or P trim and nothing smaller. It will breath better on the top end then your GT30 by far. Something was wrong somewhere. And it's not the bearings!

Many considerations to selecting the right turbo. Best to have that discussion with whom ever your planning on buying it from. Since we all work out of the same pile of parts, contrary to what some claim, it's a matter of which parts combined together work best for your goals.

 

If money really is a concern, keep your eyes open for something used that has been rebuilt. I think I paid $550 or $600 for my rebuilt Super 61 (impossible to tell that it was ever used). Anything reasonably sized will spool "fast enough" IMHO. What's reasonably sized? Any of the standard T04E compressors (50, 57, 60 trim etc). If you plan to play with more boost, you might want to look for something a little bigger. For the hot side avoid anything with a T04 wheel. Also between a #8 and a #10 housing, it really isn't a huge issue because you can swap that later if need be...

Lots of people think of turbos like tailored suits, "It must be exactly the right size." I think they're more like T-shirts, as long as its close to the right size it will work fine.

 

I will say I couldn't be more pleased with my VR stage 2 turbo. I don't know the specs and I don't honestly care. I get full boost by 3050rpms and it pulls like a train all the way to redline. I wanted something with a great powerband that delivers plenty of low end grunt without giving out up top. I'm sure other larger turbine housings would yield more top end power but, I wasn't really interested in that.

As far as outright power its yet to be on the dyno however I will say at 16-17psi its all you'd ever really need in a street 951. On the track this setup would be perfect for coming out of corners fast.

 

It is to my understanding that the KKK replica hot housings are scarce and no idea of future availability (if any).

 

Considering how large the LR75 and how effiecient it should be at high rpms, I was very suprised to see it start running out of steam at the top of the rpm scale. If there was something wrong with the setup it was corrected inadvertantly when the GT30R was installed.

Mike, you were the one who recommened the LR75 for my application and you worked with me for months to try and do something about the lag. The truth is that it was poor choice for my street 2.5L.

Anyway, your customer service has been excellent and my overall LR experience has been positive. You are on my recommended vendor list and I have continued to send customer your way. I just really did not like that turbo.

 

The PITA statement was an understatement.

If I remember correctly, we chose not to install a KKK compatible housing and ended up doing additional modifications to make it work. I don't remember the details, but there were limitations on turbine and compressor wheels with the KKK. If you wanted the latest and greatest turbine/compressor, you had to drop the KKK compatible housing. My mechanic did the work but it was a real PITA.