would I benefit swapping from a mdxt321 to a billet sc42?
 

would I benefit from the above on my 2005 sti??
im not enjoying the laggyness and I thought the car would make more on this turbo...
i feel that this turbo is more suited for the 2.5.
I think the billet sc42 I will see better results.

craig

there isn't a reliable answer to that and the only way you will find out for sure is to make the swop but I would question the reliablility of the older SC's billet or none billet, as I know two SC46's close to home were the welds have broken up in the exhaust housing, that's in the last year.
Trev

I also know of another one where the welds went aswell :cuckoo:

oh right didnt know this.. are the new ones ok?

Maybe !
You could also look at the MDX321H as that is more like the SC42 than the T is.

I've tried many, many turbos over the years aimed at specific power levels and it usually comes down to far more than just bolting it on and winding the boost up.
Often they won't hit what the makers of them say they will on run of the mill cars, because the figures posted have been done on something a bit fruitier.
The correct selection of supporting modifications can make a huge difference as can proper fuel and of course proper setting up.

We had a Litchfield Type 25 in last year that we cariied out some work on. We tested the car before doing anything and it posted a very respectable 480bhp from its 2.5 Cosworth long motor. However it was very laggy for road use and ran nearly 2 bar to achieve the figures, we thought we could do better. Intially we upgraded it's Alcatek ecu to the latest firmware and remapped it making fairly decent gains in torque from better tuning of the AVCS timing. It still didn't quite perform how we thought a fast road car should so we took the decision to replace the turbo.
We selected a 450bhp rated MDX555 from Turbo Dynamics and fitted it in place of the original unit.
Below are the figures from the original map and turbo, the remapped figures and the new turbo and remap figures.

http://i40.photobucket.com/albums/e2...ps348a9e0e.jpg

http://i40.photobucket.com/albums/e2...psd8db5812.jpg

http://i40.photobucket.com/albums/e2...ps46ab0721.jpg

In my experience, these 420, 450, 500 rated turbos share a common design as of course they would when you think about it.
For instance, a 450bhp rated turbo is likely to be based on a GT30 core and turbine wheel, have a 71mm exducer on the comp wheel and most now come with custom exhaust housings.
In essence the same thing regardless of who makes it, so they should give similar results.

thanks for that. I feel the car is laggy for a rd car. I want s fast spooling car
think ill sell or swapfor a smaller turbo

Martyn that's very impressive spool with the new turbo.
Is that on v-power or with meth ?
What was the original turbo?

I understand the exhaust housing has been changed in the new one's
Trev

I also know of two that were blowing past the welds on the exhaust housing. One was repaired under warranty the other was sent to Turbo Dynamics and had a new exhaust housing.

Yes all of the results were on straight Vpower.
The original turbo was a Litchfield/Turbo Dynamics hybrid with a twin scroll to single scroll uppipe and a 4 bolt flange.

It spooled like a b*****d when it was done :D

Also shows what a properly sorted engine will do on even the most average of turbos.

Nice one Martyn, 500+ with a splash of meth then.

Looks like the turbo I've been look for for my 2.5 to replace my SC46.

Do you remeber if it was standard 58mm inlet?
Is that with 0.60 a/r Comp cover? Would the extra for bronze bearing carriers and ceramic coatings be worth ordering?

Thanks

Easy, could have done 500+ on Vpower with more boost, 1.5 bar max !
I'd look at the rest of your set up first before you go any further, as I say it's crucial. Improve the VE and you'll make more power out of your existing turbo.
Turbo had a 3 inch intake with the .60 a/r comp cover.

What is the spec of the rest of the engine ?

Forged 2.5 (2006 sti), perin inlet, sc46 billet, full 3inch decat, ID1000 injs parallel rails, Japsrpeed FMIC, RCM headers and Harvey uppipe, Syvecs (JGM mapped), wide band lambda, 460+ on Vpower, 500+ on 20% Meth@ 1.6bar.
Just not too early spooling up not pulling full torque untill around 4400rpm
Would like to stay with 58mm inlet would this make much difference?

martyn my spec...
2005 sti uk
mdxt321
perrin inlet
d/v delete
650 injectors
induction kit
fuel lab fpr
parrael fuel rails
full 3" decat exhaust
gt spec headers
harvey smith up pipe
255 fuel pump
3 port
3 bar map sensor
alkatec ecu
japspeed fmic

You both have fairly good specs but I think the real difference between both of yours and the example shown are the flowed heads and cams. As I said, far more to making it really work than just the turbo.

Oiler I think you in particular may struggle to find a replacement turbo that may be any better than you have. The SC46 in my experience is very, very good on a 2.5.

Craig as I mentioned earlier the MDX321H may have been a better choice for you with the benefit of hindsight !

Ok thanks Martyn, it did spool a bit earlier, when it had a smaller exhaust housing that cracked, replaced it with a newer cast housing that was larger and then lost a bit.
What was the spec of heads and cams on the T25 above?
Thanks

The Type 25 had Cosworth CNC ported large valve heads and Cosworth 278/274 camshafts.
You could always have the exhaust housing replaced again with their all new cast 7cm version.

thanks martyn.
anybody want to buy a nearly new mdxt???

How much :)

not sure mate to be honest. I also need to find another turbo