Turbo Choice
 

I'm almost ready to order my new big single , for those who dont know I run a semi peripheral ported 13B REW with a Pro jay intake etc , I plan to run 25 - 30 psi boos max.
I've posted asking what turbo I should get a few times but havn't gotten the response I hoped for , so Im asking one more time .
The choice is between a GT4508R , GT4708R or the GT4718R , I am leaning to either of these because of the huge turbine wheels they use , I know this would be ideal for my p port . I know the 13B will spoll a bb GT45R without any problems, 'cause I'v seen it happen , but I'm wondering about the GT47 , would this one be too much of a good thing ?
Please let me know what you guys think and please lets try to keep this one as factual as possible , I can get all three of them at the same price so I naturally want to make sure I'll be getting the most I can for my money, thanks in advance guys.

Thanks alot everyone !

I've started to realize that if you want a question answered, or even viewed, by more than 2 or 3 people you gotta hit up the general forums....

Let me know how it turns out Marcel, because when I am done shooting through my GT4202 (T51r SPL) - I may go with a GT45r myself. I want to see some actual results though, so please keep us posted =)

have a little more time before I actually order (minor set back) , so I'll bump it up to the top.

i may be speaking out of turn here, but my sense is that you haven't gotten any responses because not many people have the experience with those units. shit, i don't think many have experience with semi-peripherals. people see someone with something that yields good results and they jock and try to copy it - hence, your HBPs with 42Rs hanging off of them. oh and before someone decides to take offense to that statement, i'm not bagging on HBPs with 42Rs, i'm just saying that many people like to follow, not lead.

personally, i wish i could give you some experience-based advice on the semi-peripheral setups, but you're well ahead of me in that respect. i guess that's why i'm watching you so much. :)

Why only 25~30lbs?
If that's really your limit then i would suggest the 45R out of those listed..

Have to agree and even then for that low of a boost pressure on gasolene you're going to be better off with a 42r especially for a street car. But I guess to each their own.
Instead of basing turbo size on boost probably you should set your horsepower goals and then pic the turbo size to accomodate.

Great , finally some responses !


25-30 sounds like a good amount of boost , but I may be going above , since I'm going "all out" with my build . But why would you suggest the 45 doesnt the 4708 have the same compressor , the only difference being the larger turbine ? I would think the larger turbine would be good for the semi. pp , do you think I would have difficulty moving the larger turbine wheel ?

If I could get a GT4202 102mm compressor with the GT4708's 92.7mm w/ 82 trim turbine , I think I'll have the best choice

I am currently building(buyin parts) a Half-bridge 45R. My goals are 740whp at 30lbs. I am not sure how far off I am on my calculations(guesstimations), but a semi pp on the same size turbo @ 30 lbs, I would like to guess that you should make at least 40 whp that me. I would also assume, you are reving higher than me as well.


Ty

U plan on getting 740whp and U think I'll get 40 more than U ? I wish , hope and pray !!!! , but realisticly I dont expect anything above 600 ! I look forward to being PLEASANTLY surprised though !
Dono how much you're going to be reving but I plan to go up to about 9500 .

go with a bw diesel turbo. gigantic hot sides, make a ton of power, durable, and cost less than half the price of the gt turbos.

I 've been hearing from Mr Alex Lopez (indirectly though) , that the Puerto Ricans are getting very good results with the GT4718 .

I wouldn't bother with the bigger turbo's if your not going to run more than 30psi. I know what your trying to get at with the bigger turbine. I had made a 4202 with the larger 90+mm turbine for a customer, I have no idea what he did with it or if he has even used it yet. I was lucky enough to source a wheel and get it together. I say run the 4508 and call it a day if you keep your boost that low. The turbo side is much larger dimensionally when stepping up to the 47,55 etc.

-S-

Thanks for expressing your views Zero , I will keep them in mind . The 4508 seems good , but the larger turbine of the 4708 can only be a benefit to mo motor and it retains the same 108mm compressor of the 45 , I am more or less set on one of the 47's because of the bigger turbine wheels , but I am still trying to decide which compressor to go with , the 108 or the 118 . If there was a 4202 with the 94mm turbine of the 47 s I think that would be ideal.

I don't like the 45 turbine wheel for a street setup especially at low boost meaning 30 psi. That's low boost with the size turbos you're suggesting.
Plus you're not going to make any more useable power at that boost level anyway over a 42. The 45's are more suited for alcohol applicatios in the 38psi plus range.

Actually I'm also doing a single turbo set pretty soon, and I'm looking at doing the gt4094, which is the upgrade from the 4088. I think you might wanna give that a try, especially with that type of port you have, you should go with a larger turbine a/r. Well that's my suggestion.

I totally understand where your coming from with it, but I see no benefit at the levels your shooting for. I have two cars here both run alcohol both need the larger turbo your looking at, you do not at those boost levels on gas. Chris is right, it's not going to net you much of anything other than weight and turbo envy ;) I wouldn't go any larger than the 4508R and probably say 4202R is enough. If your not stuck on a BB unit I can more than likely get what you would need to run the 87mm turbine with the 102mm compressor I wouldn't go for much more than that at 30psi and lower. Look into those bigger turbos in the 40psi and up range.

Pic of the 1.8ltr alcohol car we tuned on saturday :)

I to understand what you're saying , but what I cant figure is why you would recommend the 4508 as the largest choice , but not the 4708 . Both turbos share the same compressor section , as you know.. is it that you think the 94 mm turbine wheel is too large and would hamper the turbos performance? I am trying to choose a unit that will allow lots of flow through the tubine to keep engine back pressure to a minimum , I am thinking , if I go with the larger , higher flowing turbine , the boost "kick in" point can be easily set pretty low in the RPM range by using a smaller a/r , like the 1.23 (, which by the way , outflows the GT45's largest housing - a/r 1.44 ) and the roller bearing option.
I have repeatidly seen guys try to get the flowand power out the turbo by going with rediculously huge a/r's , but this , as I am sure you know , results in excessive lag , I really don't think this is the way to go .
As for the ball / roller bearings , I will not buy another "sleeve bearing " turbo ! I was fortunate enough to experience both bearing types and I am now TOTALLY sold on the former , I am quite aware of what some people say , but I know differently .
Chris , why don't U like the 45 turbine wheel for a street setup ? can you explain a bit more ? I guess if you dont like the 45 , the 47 would be out of the question ?

30psi that is why, your idea of bigger better flowing turbine is sound, but there comes a point when your not getting much better for the price paid in size and weight or response. The difference is size between a 45R and a 47R is the same as a 42R to a 45R you will be stepping up the hotside quite a bit. I'm all for big wheel smaller housing, versus smaller wheel big housing, that's just me, so I agree with you there. What I'm saying is your getting a turbo that is just not needed for the boost level you want to run. You will be trading some response trying to get better response is what it looks like to me. It's equivalent to saying I would rather run a 42R@15psi than run a 35R@15psi the gain is minimal at 15 psi but the overall feel and such of the car is far different. Yet when you turn the two up to 30psi there is a huge difference. Your wanting to use a turbo that works well at 40psi+ where it is not needed. And keep in mind I'm pretty sure your comparing T4 versus T6 flow on those maps, I would need to confirm it, also A/r is a function of wheel diameter to some degree, so a 1.15 on a 82mm wheel is far from the same as a 1.15 on a 93mm wheel. Of coarse the 1.23 will outflow the 1.44 it's based on a wheel that is 11mm larger which in turn is then requiring the larger "frame" (for lack of a better way to put it) A/r. If you want to run it hey I'm not saying it wont work, however you have two pretty knowledgeable guys (Enzo,Chris) and myself(like to think I know a thing or two) saying there is no need if your not pushing 40+psi. You will have more than enough turbo with a 45R, Personally I tend to agree more with Chris a 4202 would be plenty
for 30psi or less pick you hp number then start there.

-S-

If your not stuck with ball bearing, then their are units like you speak of. One of my buddies from Puerto Rico bought 2 of the 102mm compressor units with one running an 87mm turbine and also one running a 94mm turbine wheel. They are GT42 sized and the units use T6 housings.

I would really much prefer the BB option , I guess I'll have to start looking around for a shop who has started to custom make me one of those units.

Ok Zero , I understand U ....If I cant get a custom unit put together , then I'll go with the 45R and call it a day . Thanks for your help.

Just so you know, I'm not in any way knocking your idea, I think the 42R with the 87mm turbine is perfect. It has a very nice wheel ratio. While not stepping up to the very large(dimensionally) turbo's.

-S-

You do know that there are non ball bearing units that out spool a BB Garrett?
Not to mention you can get any combination of compressor and turbine section to suit your needs.

http://www.bullseyepower.com/
http://www.bullseyepower.com/S400.asp

BTW. 99% of the quickest cars run those not that it have any bearing on your setup and goals but I just thought I'd mention it. :lol:

Excuse me Marcel for a sec.:)
 

https://www.rx7club.com/attachment.p...7&d=1185845310

And?
Spill the beans Sean!!!