Is there really a differance in performance using the 99 spec vs 93 spec twins?



I want to run 15psi sequential however I know thats pushing the 93 specs pretty hard.. however will the 99 specs hold that better or about the same?



just well I can always rebuild my 93 specs and make them like new, or i can put the money towards getting a good used set of 99 specs from japan to use..



I thought about BNR's however I just dont want um.. I want to keep it stock parts, if anything just OEM rebuild or get the compressors clipped if its possible on our twins..



to run the stock twins at 15psi reliably what do you guys suggest? 99 spec? or rebuild the 93 specs and just have at it!?

AFAIK, the S8 twins are just a bit more efficient but nothing "heavier duty" than the S6 twins. I believe the shaft size, bearings etc. are the same. That's why folks turn to BNRs.



Have fuel, cooling and engine management in place, with a professional tune. https://www.nopistons.com/forums/pub...IR#>/smile.gif

I've been there and done that stock twins on 15-16 psi, it produces way to much heat, and you effi ciancy go staight into the ground. no hot laps with that setup.



single is the only way to go. i dont know if you have ever tried diaging the sequential setup but it sucks. if your stuck on twins at least run them non seq, far



less vaccume lines and a little more reliable. I would also have a couple manifolds sitting on the shelf !!!!!!!!!!

well i have the non seq setup but im going to trade it off for a full sequential setup.. My goal is to hit around 340rwhp while being sequential..



I plan to evenutally upgrade the solenoids to the rob bailey ones i believe there called. and rebuild the twins to like new condition and run a fresh motor.. thats my plans for the future.. but my HP goals arnt sky high like most others I want to keep it very streetable but also close to stock.. I have heard of people making more than 340 at the wheels using stock setup so I dont see why i couldnt with mine.. I just want the best set of twins for the job..

There isnt really any good reason to switch to the 99 spec turbos if your stock units are ok. They are supposedly slightly more efficient but nobody really has ever shown definitive proof of a substancial increase in performance.



If the old ones need rebuilt any way, then whichever you decide is the better deal

I have noticed the 99 specs spool a bit faster then the stock ones. That is not the only one reason I got them. A good set of used 99specs can be purchaced for $900. Considering the **** used turbos people sell for $400 that was enough to win me over.



If you want to boost more go with the BNRs. Anything over stock boost you will need to modify your fuel system and so much other stuff. Is it worth it? For me no, but it all depends (If I had more money it would be worth it hahaha)

issue is if i go bnr's then say f it i want non seq! then i should have just went single to begin with..

You want 15 psi "reliably" but that's 50% more than stock. Even accepting that turbos are a consumable (not unlike clutches, brake pads etc), that's likely to shorten their life significantly. And it won't matter if they're 99 spec or not. You can buy a few sets of used twins and just keep changing them out every year or two depending on they're condition. Or.....IMO, if you want sequential turbos that will deliver at 15 psi reliably, and still keep the car very streetable... re-consider BNRs.

As for staying "stock", other than a relatively simple modification to the 'Y' pipe, I can't think of anything else that you need that you wouldn't need anyway with a single or stock twins at 15 psi.

My .02.

If you want to stay sequential, go BNR's. You can get them sequential. Then run 17psi all day long and have a blast.... Literally... if you don't do the supporting mods.

My 7 has the 99 stock turbos and pumping out 369rwhp at 7psi. Although my 7 has extensive mods. AFAIK the 99 turbos are high flowed.