V8 Garrett T25 turbocharger

[DanT]

Anyone know if Garrett they are making anymore of these turbo's or where you can get two of them?

 

The Garrett T25 is a TB2531 series
The Garrett PN# is 452218-0001
The OEM Lotus PN# is A918E0060F
The Garrett Cartridge # (CHRA) is 443854-0146
The Garrett Service kit (rebuild kit) # is 709143-0001

[mike_sekinger]

I have two new geniune A918E0060F turbos available of you need them.

I do not think that they are available anymore.

If your turbos are no too bad, then you could probably get an aftermarket CHRA.

PM me if you are need the new units.

Mike S

[mike_sekinger]

Sorted.  Thanks !

[cschriks]

Hello, I need two new turbochargers for my V8. I am not looking for more power, only higher reliability.

What are my options?

[mike_sekinger]

Are your current units fit for a rebuild?

[cschriks]

Hello Mike,

They are still working, but need major servicing at some point. Instead I was thinking of fitting new ones.

Hopefully there are turbo's that have become more reliable. I am reading about these 360 thrust bearings that people seem to recommend.

Can you advise me?

[mike_sekinger]

Genuine new replacements are pretty much unnobtainium at this point.  If yours are still serviceable, then you can have them rebuilt to include a 360deg bearing pad and staggered gap oil seals.  This would be by far your cheapest route.

Try contacting one of these companies:

Turbo Dynamics | Turbocharger repairs, replacements & performance upgrades

Lotus - Ramspott & Brandt, Ihr Spezialist für Lotus-Esprit, Lotus-Elise und alle anderen Lotus-Modelle (ramspott-brandt.de)

[lotuslover1]

hi,i had mine rebuilt and hi-flowed with billet wheels.They come on sooner,harder and longer,i was so impressed.

[mike_sekinger]

Good job.  That`s about as far as you can go with the small frame 0.49a/r compressor housing.

I have the same but also cut-back the turbine side to reduce back pressure.

This is an interim set-up until I can complete the tubular exhaust manifold set-up and install the BorgWarner EFRs.

[C8RKH]

I love threads like this on TLF and am so in awe at how supportive, skilled, and resourceful people are in keeping the older models going better than when they left the factory!

Piccies are good too. Thanks.

[lotuslover1]

Thanks buddy,i did the ECU,injectors and intercoolers and she goes pretty good now.

[MD355]

Since we are on the Garrett T25 turbo subject, there is oil smoke from one of my turbos and probably the journal bearing of the cartridge will need repairing..

A friend told me to check if I can make the stock Garrett T25 turbos ball bearing... Is this possible ?

Has anyone done it ? Is it worth it moneywise ?

Would you do this upgrade in combination maybe of making the turbo hybrid (larger compressor side) ?

Thanks !!

[mike_sekinger]

If you wanted to move to a more modern ball bearing turbo, then you would need a different turbocharger.  You cannot adapt the existing CHRA to move over from journal to ball bearing cartridge.  If you wanted to go that route, your challenge would be to find a small frame turbo that would physically fit with and around the existing hardware, plus likely adaptions to the exhaust flange on your downpipe.

Giving that the engine is not providing optimised power, throwing money at expensive turbos doesn`t make a great deal of sense unless combined with intercooling and other performance upgrades.  I guess as time goes on and the original T25s are becoming more scarse, it could make sense to find a modern equivalant, but it is not likely to be "plug and play".

[MD355]

Thanks for your reply !!

As the Esprit V8 is my first and only turbocharged car, I have noticed over the years of ownership that sometimes the turbos spool progressively and sometimes they seem to take forever to build boost (huge turbo lag).

I read this article regarding the turbo from the 4-cylinder S4 and it explains how ball bearing turbos have very little resistance http://www.wcengineering.com/esprit/turbo.html

Does this mean that if there was a way to upgrade the V8 turbos to ball bearing they would have much less turbo lag ?

By the way, I am trying to understand what A/R means and how it makes a change on engine performance.

I read that A/R is basically Area of turbo inlet / Radius of turbo (is this exhaust turbine radius ?)

What is stock V8 Garrett T25 A/R ?

I am using this thread to learn more about my car, so thanks for your patience...

 

[Thartje]

On 05/11/2023 at 16:06, MD355 said:

Since we are on the Garrett T25 turbo subject, there is oil smoke from one of my turbos and probably the journal bearing of the cartridge will need repairing..

 

 

If you have a turbo that is smoking there is usually an underlying issue. I would see where the oil is coming into contact with the exhaust from and go from there.

 

3 hours ago, MD355 said:

As the Esprit V8 is my first and only turbocharged car, I have noticed over the years of ownership that sometimes the turbos spool progressively and sometimes they seem to take forever to build boost (huge turbo lag).

I read this article regarding the turbo from the 4-cylinder S4 and it explains how ball bearing turbos have very little resistance http://www.wcengineering.com/esprit/turbo.html

By the way, I am trying to understand what A/R means and how it makes a change on engine performance.

I read that A/R is basically Area of turbo inlet / Radius of turbo (is this exhaust turbine radius ?)

What is stock V8 Garrett T25 A/R ?

I am using this thread to learn more about my car, so thanks for your patience...

 

Boost should build the same every time and is based where you are in the RPM range/power band. Flooring it at low RPM and outside of the power band wont build boost. Flooring it at 4k RPM should see pretty instant boost with the tiny V8 turbos. If boost is building slowly you're in the wrong gear.

Converting to a ball bearing turbo would be a pretty minor change in the turbo efficiency. If the turbo is sized correctly for the application you might see the boost from a ball bearing turbo come on a few hundred RPM earlier, it wont be a night and day difference.

A/R concern is on the turbine side. You've got the concept correct on the math. Bigger A/R = more flow, slower spool. Smaller A/R = more constricted exhaust flow, turbine spools earlier, turbo has a lower max RPM.

The stock exhaust AR on the Esprit v8 is .49 A/R. Its incredibly tight, but one of the reasons boost comes on quickly in the V8. Increasing the exhaust A/R on the Esprit might actually net more of a gain than changing the compressor to the largest you could fit... if they made a larger exhaust AR that fit.

[lotuslover1]

When i spoke with the turbo shop,they advised that the design of the original esprit turbos was 30 years ago and that the newer billet designed wheels would flow more and spool earlier.He was right and it made a huge difference.Ball bearing centres would probably improve it even more but would probably be twice the price.

[Thartje]

9 hours ago, lotuslover1 said:

When i spoke with the turbo shop,they advised that the design of the original esprit turbos was 30 years ago and that the newer billet designed wheels would flow more and spool earlier.

It would be interesting to see a dyno comparison with no other changes. Butt Dyno after mods will always add 10-15hp 😂Depending on the billet and cast wheels the billets can be heavier.

 

I'm sure it's an improvement in efficiency but would be interesting to see where the changes are overall.

[mike_sekinger]

Putting the latest high efficiency 11 blade billet impellor and ball bearing cartridge turbos on an 918 engine which does not have any form of chargecooling makes little sense beyond bragging rights.  Given that the engine makes peak power under favourable conditions only.  For those owners that live in high ambient temperature climates, you will feel the difference in power output on cold days.

It is a different world when you are away from the forced fuel enrichment for intake temperature cooling.

 

 

[Thartje]

If PSI is kept the same and efficiency is being improved the 11 blade would bring a benefit of lower IAT and more power. You're not going to be worse off.

If there was a way to tune the car to lower boost you could keep the same power at lower boost and much lower IAT however.

Compressor efficiency has come a long way in 30yrs.

[mike_sekinger]

Don`t get me wrong, I understand that turbocharger technology has come a long way since these units selected.  I also have the 11 blade billet implellor on my hybrids but in terms of "bang for buck" splashing out on a pair of new gen. ball bearing turbos on this stock application would no make economic sense from my opinion unless it was part of a more extensive performance package.

[Steve V8]

My original CHRA's were unserviceable due to wear and corrosion, the parts required no longer available, so I've ended up with these.

Original housings machined out to accept new CHRA,s, with thanks to Tubo Dynamics.

 

[Thartje]

4 hours ago, Steve V8 said:

My original CHRA's were unserviceable due to wear and corrosion, the parts required no longer available, so I've ended up with these.

 

Original housings machined out to accept new CHRA,s, with thanks to Tubo Dynamics.

 

 

What did they end up jamming in there Steve? I have my old turbo's sitting in a box, trying to decide if I should do anything with them.

[Steve V8]

5 hours ago, Thartje said:

 

What did they end up jamming in there Steve? 

Not sure what they are Tom, the difficulty here being the availability of parts, so compatability with the existing housings and oil drain positions being more important than performance gains for me on a factory standard engine.

Having said that slightly larger turbine and impellers have been fitted into the re-bored housings, I'm informed performance gains will be negligible, but reliability will be greatly improved, I'm guessing that refers to 360 deg bearings being used as apposed to ball bearings. 

I should have asked that question.

 

[mike_sekinger]

Turbo Dynamics offered (subject to part availability) various stages of upgrade.  If they are stating negligable performance gains, then it is a mild step-up.

[Jason Rushing]

I had PT Turbo in California rebuild mine and they are basically T28 hybrids now with billet compressors, oversized turbine, and the 360 bearings, plus I asked them to do the ceramic coating to the turbine housing. They had to machine the turbine housing to accommodate the new turbines, mine had some damage and the T25 turbine is not available from what was explained to me and what they installed is used on some T28's so that is why I use the term a T28 hybrid now but all in the original housings. I haven't had the car out for a test drive yet but that should come soon!

Last photo is what the old compressor wheel looks like for some comparison.

 

 

 

 

Edited November 28, 2023 by Jason Rushing
Add additional photo of old turbo