Thread: Garrett GT28R on 300Tdi

Well, with more fiddling with the injector pump tuning I'm convinced that the GT28R (GT2560R) is, as suspected and suggested here by a few, too big for the 300Tdi. I've managed to get the EGTs down to an almost acceptable level, but it just won't spool up like it should.

So, are any recommendations for a replacement? It seems the GT22V is the ultimate way to go but that's going to require a manifold and exhaust flange change. I currently have a T25 manifold with the 5 bolt exhaust flange.


James.

A discovery TD5 GT2052 will be an improvement over the original.

Just my 2c's worth.

The stock 300Tdi turbo is based on a Garrett T25 core. As is the TD5.
The 300Tdi turbos I have had all had a larger compressor exducer (OD of impeller) than the one used for TD5's.

The GT28 is a replacement for T25's.

Turbo manufacturers make a few changes within each core/family size to make a particular turbo more suitable for the particular engine. For example:

The turbine impeller generally remains the same.

The A/R of the turbine housing is changed to suit the particular engine. Small A/R for smaller displacement engines or lower engines that have lower EGT (diesels). Smaller A/R spins up quicker but at the high end a waste gate is used to prevent the turbo from over speeding and to reduce back pressure in the manifold that reduces performance. For a 300Tdi a GT28 would be better with 0.64 A/R.

On the compressor side, the exducer and trim are tailored for the particular engine. Exducer diameter to suit boost pressure (larger exducer for higher boost pressure - boost pressure is a function of tip velocity squared, because these type of compressors are dynamic compressors). The inducer diameter limits the air flow (larger dia for larger air flow). Trim, which is the ratio of exducer and inducer calculated as area (so square both diameters) affects compressor efficiency (lower efficiency indicates more of the torque from the turbine is wasted by creating extra heat in the charge air - bad). Increasing either, impeller exducer or inducer will require more torque from the turbine so if these are too large the turbo will take longer to spool up.

The TD5 turbo is a GT2052. It is based on the same T2/T25/T28 core as the original 300tdi turbo, but that is only the bearing arrangement. There used to be two very different turbo chassis in the garrett family, but they adopted the simpler T2/T25/T28 style core for the majority of their GT series.

Garretts GT series turbos have better wheel designs than their old T series and can spin quicker, this lets them flow more gas for the same size or in this case, flow the same gas as a T25 but through a smaller turbine. The old T25 size turbine is still used in the GT25 range (two sizes up, there is a GT22 in between).

The old 300tdi turbo does indeed run a bigger compressor wheel than the TD5's GT2052 (54mm vs 52mm), the better design of the GT makes up for the missing mm's.

Normally the TD5 turbo wouldn't be worth the trouble to upgrade, but since you already have a T2/T25 manifold if you can pick on up for a few hundred bucks it'll be your best option. Beyond that it's spending thousands on a VNT turbo.

Originally Posted by Dougal

The TD5 turbo is a GT2052. It is based on the same T2/T25/T28 core as the original 300tdi turbo, but that is only the bearing arrangement. There used to be two very different turbo chassis in the garrett family, but they adopted the simpler T2/T25/T28 style core for the majority of their GT series.

Garretts GT series turbos have better wheel designs than their old T series and can spin quicker, this lets them flow more gas for the same size or in this case, flow the same gas as a T25 but through a smaller turbine. The old T25 size turbine is still used in the GT25 range (two sizes up, there is a GT22 in between).

The old 300tdi turbo does indeed run a bigger compressor wheel than the TD5's GT2052 (54mm vs 52mm), the better design of the GT makes up for the missing mm's.

Normally the TD5 turbo wouldn't be worth the trouble to upgrade, but since you already have a T2/T25 manifold if you can pick on up for a few hundred bucks it'll be your best option. Beyond that it's spending thousands on a VNT turbo.

Vnt's from zd 30 patrols can be had quite cheap one just sold on ebay for $270 it was in very good condition (it was a friends turbo) it had been converted to air can rather then vacuam so that would be a cheap why to vnt 'your' rover.

Originally Posted by Benny_IIA

Vnt's from zd 30 patrols can be had quite cheap one just sold on ebay for $270 it was in very good condition (it was a friends turbo) it had been converted to air can rather then vacuam so that would be a cheap why to vnt 'your' rover.

The patrol VNT should be a GT2052V, the orientation may be a pain, but if you can make it fit it's worth a shot. The GT2256V that's normally used as a VNT is significantly larger, but it all depends what your goals are.

Originally Posted by Dougal

The patrol VNT should be a GT2052V, the orientation may be a pain, but if you can make it fit it's worth a shot. The GT2256V that's normally used as a VNT is significantly larger, but it all depends what your goals are.

yes i beleive a gt22v is fitted to a sprinter?

i would think (no turbo expert) that a zd30 vnt would go quite well on tdi if it could be fitted

This is really, really good information everyone. Thank you so much.

A VNT would be nice, but I'd rather not have to pay for one if I don't have to. I'll keep an eye out for a TD5 GT2052. I'm not chasing massive power and torque. I'm quite happy with my standard 110 Tdi, with a bit of injector pump tweaking, and similar level of performance for the 130 will be fine. I'm planning on an uprated intercooler and perhaps diesel-gas to help compensate for the extra weight of the 130 over the 110.

Thanks again
James.