GTK650 vs GTK850
 

do you think stepping up from a .68 to a .81 will make much of a difference in lag? been running the gtk-650 but thinking about moving to a 850. boost psi will be the same. due to the larger AR i am affraid the lag will be bad. anyone have any thoughts on this with this motor. max rpm is 7100

yes changing AR will increase lag but give you more room to breathe top end. slightly interested in those turbo specs. turbine to compressor wheel is almost 1:1. id possibly recommend going with something with a similar turbine wheel size but a bigger compressor. do you have any logs/dyno to show spool and flow on that turbo?

as far as big turbos for our car, its what you prefer, instant torque or top end? im running a 6031, full spool at 4k rpms and peak power at 6500 rpms. in the end its how you want your car to preform

I'm not familiar with either of those turbos, but just keep in mind we don't rev out very high up top to make a huge turbo worth it...
Edit: what are your boost targets/power goals? If the 650 has you at that goal it may not be worth the lag and shorter amount of time in boost from the 850

men are speaking, go back to your room

Sorry daddy chinkus

i prefer top end. right now im spooling at about the same as you full boost is in by 4400. lord knows bottom end is almost a waste when trying to get these things to stop spinning. i have some lag now but it is not bad and still has room to grow. but heat is a issue and was thinking that a little bigger might ease the work it is trying to do. here are some specs for it.

GT-K 650
Turbonetics GTK-650 66mm Dual Ball Bearing Turbo GTK650 [11262] - $1,487.49 : Real Street Performance Engine Parts, Pistons Rods Cams Valvetrain and More


boost targets are between 24 and 26 right now. any more and temps climb to the point of getting knock and pushing it harder yelds no returns. was really looking to see if you think the AR difference will be a plus of just stay where im at

this turbo was for a ls1 project and was adopted for this. been running it now since march. besides being a little rich it runs well. street manners are getting there slowly with tune but will still be awhile before it close to perfect

http://www.mazdaspeedforums.org/foru...2/#post1445664

you went big turbo that fast? what manifold are you running? there are a handful of t4'd turbo 3's and i have yet to hear of one on a genpu. im startin to smell fish, that or hamilitons mom just joined the forums. show me pics of your build

obvious fag is obvious

Nig is running 25psi and thinks he's making 550+whp.

wenis

well at 32-36 it is making 552hp and 436tq heat is making this a one shot run with those numbers that is why i was wanting to ask if that AR difference would make the thermal efficiencies increase and the compression ratios of the housings drop to help ward off heat build up so fast. at a point the system becomes too heat soaked to provide stable combustion conditions. just because it can make those nubers does not force me to push it that hard all the time. thus the lower numbers i wish to keep all the time and turn up for dyno or drag racing.

thanks for the wonderful posts i am done with this forum. and for the record it is not the first gen 2 to make over 550 horsepower. there at 2 out of houston pushing the 600 mark. manifold is hand made. same way builders have done it for years. cut your flange off and make your own to fit anything you want. daddy chinkus thanks for your input and may the pistons always stay in the block.

open the flood gates

I hate when my turbine housing gets too hot too. Makes my combustion unstable as well. ???? Anyways dynoplots, vids, datalogs.

boost numbers are generated by a restristion in the intake track, if you get your readings from intake side. less restriction lower boost numbers. so boost PSI is not a accurate measure potential of power unless you are measuring in the cylinder itself. for a turbo forum i expected more than relating the entire HP production by a guage that isnt accurate but close enough to get by.

thanks for all the fun

when comparing same motors with same displacement, head, and similar sized turbos, boost is a great indicator. Youre preaching to the choir on fluid dynamics here.

From car to car, mass flow is a better comparison.

Ill throw you a bone assuming everything you said is true....but you still need to post evrything ive stated.

If you go up to the gtk850...youre going to shift your powerband a thousand rpm over. You will have better exhaust flow at the cost of response. If we had an evo and had various aftermarket head modifications...and we could rev to 8500-9000+rpms then maybe sure. But with that turbo lag will be pretty crappy, making a dyno queen and quartermile beast. Both of which are not easy to do on our platform.

So how are you making this power. Mods, dynos, videos, etc. post them and stop whining.

im in Houston and know at least 10 different mazdas from various groups and have not heard of any 600 whp gen 2s... the only shop i've even heard of working on them is SSP and no ones mentioned any high horsepower cars from them, they basically tune bolt on cars on e85, and i think 1 or 2 BT cars that i know of off the top of my head.