serge1

Greetings,


I am planning to get the 99 spec turbo. Do you like them?? How they boost? How much power over the stocker??

Thanks
Serge

MazdaMike

i love em, im running a 10-8-12 pattern and they very resonsive. no complaints as of now
-mike

t-rex7

i tried to do a search on this but you can't use '99' and a spec turbo will bring up everything. How are the '99's better? what is different? how much? is it better to get aftermarket twins instead (like m2 or pettit)?

Thanks

`s

Dan

i just talked with jeff at pettit and he said they dont carry their turbos any more. He said all they sell is rebuilds or upgraded 99 spec. He told me that the 99's are still basicly the same turbos as compared to 93-98?. He said that the compressor wheels are the same and that the only diffrence is the housing. He told me that the old ones have a 90deg. bend on the exhaust side that cracks over time, and the 99's have a more smooth of a bend so that the air flows better. The only other thing is that they are now ciramic coated.
If I were you I would check into bnr turbos. On their site they show the diffrence between the compressor wheels. They are also alot cheeper and come with a warranty.
good luck, and when you make this leap, make sure you tells us. Their is alot of people on this forum in your place, either to go with upgraded twinns or a single.

Coulthard Fan

I like Jeff a lot, but he was either on the rock when you spoke to him or you confused what he said. I have the 99 turbos and like them for their responsiveness more than anything else. I'd say top end power levels are slightly higher than the 93-95... but I've told many people that if you are looking for a lot more top end power a single is a better choice.

Here is the scoop on the differences in the 99 turbos from Jack Yamaguchui (author of the RX7 book):

"The turbocharger, two of which are used in the sequential setup, is a new Hitachi instrument with an abradable compressor sealing and an "ultra-high-flow" turbine design. ...

[There is] a new built-up construction of the compressor housing. A formed plastic inner sealing element is bolted onto the main housing, and then machined. The turbocharger is assembled, and run up to 100,000 rpm, abrading the inner surface of the plastic seal, obtaining the closest clearance between the compressor and housing. The new abradable turbocharger has an 80%-plus efficiency, whereas a typical instrument's efficiency is about 75%, according to a Mazda designer. This brings down the compressed air's temperature by 10 C, or about 10%, at the exit of the compressor. Air temperature is still in the region of 110 C (230 F), which is further cooled down by the air-to-air intercooler in the RX-7 installation.

... The [new turbos use a] "ultra-high-flow" turbine, with its blade length extended and its shapeless acutely curved, enlarging gas passage and reducing flow resistance. Turbo response in the low speed zone has been greatly improved. The turbocharger adopts a smaller diameter turbine, 50 mm (1.9 in.) now versus the previous unit's 51 mm (2.0 in.), again reducing inertia mass. The new "ultra-high-flow" turbine realizes about a 10% gain in efficiency, according to Mazda's turbo engineer. The twin ultra-high-flow turbochargers supply a maximum boost of 74.7 kPa (10.8 psi) at 6500 rpm to the previous high-flow instruments' 62.7 kPa (9.1 psi) at the same rpm."

Word.