Anyone have direct experience with these two turbos (especially on an EVOMS GT700 kit?)?

What's the boost or torque difference at say 3000rpms and 4000rpms? Thanks.

 

Don't know anyone who has had both the old gt-28 hybrids and new tial alphas but there may be someone. I have the newer turbos on an EVOMS kit. The main difference between the old and new turbos is that the new turbos don't die off as much up top ie they pull hard up to the redline. Both turbos require significant supporting mods to be competative with other larger setups.

As far as your boost question, I would expect both turbos to have similar boost at 3 & 4 K. My understanding is spool is similar between the two setups.

Another difference is that the original hybrids were journal bearing and most A28s are ball bearing turbos.

 

I have the older GT28s and have no experience with the A28s - just hoped to run Flash68 for comparison before he went nuts with his additional mods.

I feel like I'm driving a V8 with the low end torque with these snails.

I don't do the high-speed highway pulls, only quick bursts at lower rpm and some track - these are just perfect for my needs.

 

There are three types of the "normal" GT28 turbos (one of which is current and uses ball bearing and water cooling) and one type of alpha 28.

I have the latest 2860RS. They spool like K16s and outperform K24s by a considerable margin. They will easily induce tire spin in 2nd gear without popping the clutch. Just start at 2,000 RPM and the tires will lose traction once the boost builds (around 3,000 RPM). I tested it and it will build full boost of 1.2 BAR by 3,000 rpm in the higher gears.

The Alpha 28 is a much bigger turbo with many of the above characteristics. I drove Yellow Turbo's A28 car at similar boost levels and felt it was comparable. The Alpha will outperform at freeway speeds.

One thing not often discussed is that 1.2 BAR is about the limit of pump gas. maybe 1.3 if you have access to 93 octane.

 

I have like the 2nd of 3 revisions of the EVO KIT. Its the complete center section and front housing of the newest Alpha turbo with just the older turbine housing that is bored out. I have ball bearing turbos with water cooled center section. It will spool at .2 BAR if I'm cruising at 90mph on the highway on cruise control. It does not die up top at all now that EPL has edited the boost maps several times.

The main reason I heard Tial came out with a complete turbine housing is to save on the hassle and time of maching out the stock k16 or k24 turbine housing. At the same time I'm sure it is probably ideal out of the box for flow compared to a Porsche casting that is ported. I love the things they rock out very well.

 

Off hand ... what would the supporting mods for the GT28's?

 

injectors, exhaust, dvs, filter and a tune...
then ICs, plenum....

 

+1 to the alpha's, these are wicked turbos and are featured on our P800 package.

 

all bolt ons... no engine work?

 

I have an all bolt on kit. Dyno and mods all listed in my Sig (91 octane).

Note that a 5 bar FPR will likely fit all your fueling needs for pump gas. That said, Injectors are the "proper" way to do this and is probably worth the ~$700 difference in parts and labor cost.

 

do you know if I can get the old GT28s rebuilt with ball bearings? I have one turbo with bad bearings, trying to decide whether to rebuild both or upgrade to alphas.

 

Upgrade. TOTALLY different turbos. Much more potential.

 

your running modified alpha 30's ?

 

Any idea when these upgrades were made? I bought my car with the GT610 kit on it and I am not even certain what turbo's I have.

 

If you have a purely track car, the old hybrids are not a bad choice, instant spool.

They die out up top but by then you are in the turn, even on big tracks like TWS.