silvrhand

This was a very informative post from another site that I wanted to add here for sake of having the information available:

: Ok, there are a lot of comments about different turbos avalible for our cars here and a lot of dis information floating around so here is my attempt to answer some of those questions, this is all my own opinion and a lot of other experts will disagree with me as they have the right to do, but here is an engineers analysis of the different turbo combos. I know a little bit about turbos, you might have read my series on them in SCC the past few months.
: First I have to apolgize for my spelling, it basicaly sucks and you can't use a spell check here. Anyway, here is my views on some of the most talked about turbo systems out there for our cars.

: Greddy TDO5-16G
: Pros:
: A pretty good turbo system, pretty good efficency, about 76% over a fairly broad range on the compressor side, mid 60's in the turbine. Good flow, about that of a small trim T3/T4 hybrid. The greddy stainless manifold is a huge advantage over the stock POS manifolds. External divorced wastegates are very good for improving discharge flow and tight boost pressure control. Better manifold design keeps these puppys spooling even if they are big. Probably the best all out power combo for the Z32 on the market.

: Cons:
: The manifold is not designed properly for the material selected and thus will eventualy crack due to stainlesses high coefficent of expansion, Needs turbo supports, floating slip joints and bellows to live. Rewelding only delays cracking. The engine has to be pulled to deal with issues. Open wastegates sound like *** (my personal opinion some like the sound) One **** to install. Double Expensive. Mitsubishi technical data like compressor and turbine maps is hard to come by so gotta take the sales guys word for it.

: HKS GT2530
: Pros:
: Well matched compressor to turbine. Very efficent High B width 60 trim T-3 in a large diffusor .60 a/r TO4B compressor housing. About 76% efficent here over a broad range. Can flow about 27 lb/min. Excellent 9 blade NS111 turbine with an excellent 72% efficency and 16 lb/min flow capacity with the .64 a/r turbine housing. Double excellent Garrett double ball bearing floating cartrige center section. One of the best turbos you can bolt to the stock manifolds.

: Cons:
: The stock manifolds suck rocks, full of back pressure and contribute to lag and reversion. Should be made avalible with a .86 a/r turbine housing as an option. That would be good for about 40 more hp and hardly lag any worse, maybe 500-600 rpm more lag. Expensive. Needs custom down pipes.

: JWT Sport 650'S
: Pros: excellent compressor efficency, 77% over broad range, 69% turbine efficency. Compressor can flow over 30 lb's hr and the turbine 19 lbs per hour. Very good turbo, cost is reasonable compared to other two. Better flow than HKS. Better power potential than HKS. The most powerful turbos you can bolt to the stock manifold. Dual Garrett ball bearing CHRA version should be coming soon! A real T28.

: Cons: No ball bearings, needs custom down pipes. Slightly laggyer than GT2530 due to bigger exhaust housings, no ball bearings and less efficent turbine which is almost compesated for by more efficent compressor. Uses sucky stock manifold. With Ball bearings, this should be the ultimate bolt on turbo. More efficent than TDO5 but slightly less flow with inferior manifold probably makes less power.

: Brand X Fake T28 (from various "upgrade" companies including many famous ones)

: Pros:
: Cheap, people on forum with no dyno access think they are good. Bolt directly to stock downpipes.

: Cons:
: A big POS. These are big 65 trim T-3 compressor wheels carved to fit in the stock .48 a/r T25 compressor housings. This sucks as it effectivly eliminates the diffusor section of the compressor housing. About 30% of the air's compression takes place here so it is critcal to maintain this. Old 40's turbos had no diffusor and were less than 50% efficent because of this. This sort of compressor upgrade might flow better but will heat the carge temp to over 300 degrees F at 20 psi of boost. You can see these suckers instantly boil ice water sprayed on intercoolers on the dyno at high boost. Very peaky power output. The turbine is usualy a 68-79 trim (depending on company) T25 "G" (there is really no such thing as this) carved into the stock T2 .63 or worse yet .48 a/r exhaust housing. Although the exhaust side is not as sentive to wheel to housing geometry, the smaller housing flows worse and is less efficent. Poor efficency all around leads to lag and backpressure. Backpressure leads to reversion and detonation. Notice that many people that run these turbos seem to have engine failure? Compressor to turbine mismatch also results in thrust bearing failure.

: The lag and peaky power these piles make fools people into thinking they are fast.

: JWT sport 500, 600
: Pros:
: Correct wheels and housings, with oem like matching of componets to function right. Cheap and relaible. Good on stock motors. good replacments for smoked stock turbos. Sport 500s are direct bolt on replacments.

: Cons:
: Not as much power as other stuff. Not sexy.

: HKS Sport turbo
: Pros: About the same as JWT sport 500. Same internal componets. Sound engineering and matching.

: Cons: Need custom downpipes for 5 bolt housings. Either get sport 500's if you just want a close to sotck upgrade or get the GT's if you want power, not worth the money.


: Other aftermarket upgrade turbos
: Pros: Cheap?

: Cons: Same as fake T28. Conceived by aftermarket seat of the pants kind of guys, not engineers. Turbos are not that sort of product.

: Well here you go, that's about it for now.

: Mike



- john