Hello friends.

I am looking for garret based turbo larger (hotside) than a GT4202 in journal bearing, preferably in T4 divided Ideally a GT4508 T4 would be perfect but it only comes in BB and for budget reasons I cannot justify buying a 3k$ turbo at this time. A gt4202 would be on the small side of things but could meet my goals although I might loose a bit of top end powerband. A GTK1000 is BB, in the budget and will flow enough air for the HP level I want but is too small on the rear end for the powerband I seek from the 20B. A journal GT4708 would be ok and similar in size to a GT4508 but it only comes in T6 unless I go with a precision custom unit, which is still quite a bit above 2k, with a T6 and the larger turbine wheel will hurt my spool. I ran into the Precision Turbo PT88, which has an 88mm inducer compressor, is T4 based but has a turbine between the GT4508 and the GT4708. This turbo is only available in open volute but is significantly smaller and promises enough air for my goals, not to mention its only about 16-1700$. Does any one here have any experience with this turbo in Rotary applications? Should I just go with a GT4202 and call it a day? I know about turbo nomenclature so feel free to bring it with your answers, I also know that I want to stay T4 based and divided if possible. The reason I would prefer Divided is so that I can use a "Quick Spool Valve" of sorts...and T4 because of packaging issues, it is not a racecar, I need to optimize space.

Thanks in advance,

Chris

 

I think you should use the T6 Undivided. (GT4708)
Everything else is just too small

 

I see...I think its a little too much for my goals...but the real problem is its size...its tight...and I am trying to stay with something a bit smaller...at least with 5" inlet and not 6". I am worried about lag and the engine will not have agressive porting, more like a mild street port. I am looking for low psi but a long powerband at least to 8500 and that usually takes a large hotside impeller. Any recomendations?(even if not garrett based?)

Also, I called you and didnt get a hold of you last week. When is the best time to call you? I am off at 5pm(6pm your time) and have a long drive home. I want to clear up your ECU and intercooler questions and talk a bit about a gasket that the intake manifold needs before it gets installed onto the Renesis.

Let me know and thanks.

Chris

 

Gt47 use a t6. Gt42 use a vband. Gt47 has turbo lag. Gt42 spools much faster and makes power early. Gt 47 will make more power for drag racing and will have lots in wheel spin + destroyed drivetrain parts. Gt42 would be better for daily, road racing. Depends what u want.

 

See I think of it differently. A harder hitting turbo AKA GT42 will make more torque early and that is what will break parts. A softer hitting(laggier) turbo AKA GT47 will be a bit easier to control and smoother power delivery and less broken parts. It also will not be restrictive at higher boost levels/rpm

What is your HP goals? What Fuel? IF your only shooting for 700 or lower then I would say GT42. Anything higher and the GT42 will really start to backup.
I would 15psi~18psi with the GT42 would be a happy spot and anything higher I would probably look at different turbos.

 

I am looking to stay at or under 700whp at least for now. The engine will be built to handle more but I want to keep it under that since more is not necessary on the street. The issue is that the 20B's I have seen with GT42's fall on their face at about 7500 more or less even at low 12psi boost settings and mid 500whp numbers. I want it to hold its power until at least 8500. I think running less boost but holding torque for a longer period of time is great for putting the power down, especially on the street. To give you an idea, my friend from PR has a GT4788R and he keeps it at 14psi, it puts out over 700whp with a nice flat powerband and it makes power climbing until 9k rpm. But he is also Automatic with long gears so he has no issues spooling, not to mention that his turbo is BB so that helps too. He has gotten the car to the 1k mark, part of the reason he has that turbo. I am looking to stay under 700 for ever so the GT47 seems excessive (at least for now). I want the same power band without chocking on the top end but I don't need as much air as a GT47 puts out...I'm basically looking for a GT47 turbine wheel with a GT4202 compressor and an A/R of about 1.00...that would be ideal, as weird as it sounds.

As for fuel, I live in E85 land (MN) and that is what I was running on the renesis and will run on the 20b. BassicallyI want a very safe and reliable 500-700whp car.

Any recommendations outside the garret family? I know you have experience with the borg warner brand...

Thanks.

Chris

 

Not wierd at all.. But that's the problem the GT42 is just too small turbine wise to work well.

You know what I think might be a better choice is the BW S475, although your back to a T6 housing. You really need the bigger turbine wheel/size of the T6.

BTW I use BW and Garrett .

 

Hmmm...they do make the BW in T4 with 1.1A/R but it gets way expensive compared to the T6 1.32A/R that you can purchase for 6-700$. Who has used these in their 20b's that could comment on spool up?

They do make a T6 quick spool valve...Hmmm....

When is it best to call you to talk about the RX8 install? LMK

Thanks.

Chris

 

Talk to Forced Inductions, they have a few options(http://www.forcedinductions.com/productsgarrett.htm).. or look at the Precision PT88-47. it is a gt47 88mm stuffed in T4 housings.

 

What?!? I could make a liar out of you by changing the hotsides around on the turbos.

What ever happen to comparing compressor maps with your specific engine & porting? Thats part of how you should properly match a turbo with your engine.

 

I am not concerned with the compressor side. If I go by compressor maps then a GT4202 is right on the money for what I want airflow wise. However, I know that the GT4202 will not give me the powerband I am seeking. For this I would need a turbine at least as big as that of a GT4508R. That is my dilema...do I buy a huge turbo for the hotside but then suffer unnecessary lag from more compressor than what I need or do I go the other way?

Chris

p.s.thanks for the replies guys.

 

i have tried a few different set ups and i'm very happy where it is at right now. i run a BW s480 with a 1.10 hotside t6 divided. i start building boost around 3000rpm and full boost around 4500ish all the way to 8k no problem and makes 620whp @ 17 psi.

Call mike turbo in miami http://www.miketurboinc.com/ and ask for Hong and tell him Carlo from orlando with the 3 rotor sent ya he will help you out.

i hope this helps

 

if you really want to pay, you should just go with a tial v-band housing. i know you can get the gt4202 with a 1.0 hotside, and its along the lines of a T5.. lol

 

I'm using a BW with 1.1 A/R T6 housing, it's only $599 from here:
http://www.forcedinductions.com/productsborgwarner.htm

It spools pretty nice and linear, kinda like a T04S or GT35 on a 13B. The 1.32 housing has bigger turbine exducer 96mm vs 83mm for the 1.1 turbine (at least the one they offer), which makes up for the lag quit a bit, I'd venture to guess that the lag difference is not very big between the two.

I think my next turbo may be a S480 with 1.32 housing... But that'll be a while since I'm taking my time getting all the little issues worked out with my car...

 

so running a bigger wheel helps against lag on a larger rear housing?

Id assume the 96mm with the 1.32 would still come on full boost later than the 83mm with the 1.1 turbine though?

 

According to Hong i have a 1.10 milled to fit my 96mm exhaust wheel. the turbo spools a lot faster compared to the 1.32 that i had on there before. Port type and exhaust has a lot to do with it though..

 

So, isn't 83mm on the turbine side smaller than what a GT4202 has for a turbine? hmm...how is your powerband? Where is your peak HP and at what point does it drop off? Very interested...might switch manufacturers if this works...for $599 you can't really go wrong. There is also the 80mm version for 899 with a 1.1, not bad.

Thanks for all the comments.

Chris

 

Chris Call Hong i think i paid $399 for mine

 

You paid 399 for what? the 1.1 housing? why? does it fit the 96mm wheel? Thanks.

Also, I would like to keep it T4 based, is this a possibility?

So between a GT4708 Journal with a .96A/R and a BW S475 1.1A/R 96mm wheel like yours, which one do you think would spool quicker?

Thanks.

Chris

 

Bewtew has the best of the both worlds. You want to maintain a high exducer to inducer ratio before you step down on the A/R, for both response and output.

 

Just off the top of my head, 83mm is just the exducer (comparable to the GT42 or slightly larger still), the inducer is still way bigger than the GT42 turbine at 102mm or something like that.

 

Bewtew, can I get the contact info of this Hong person? Is $399 for the turbine housing or the whole turbo??!!

 

Nice.

On http://www.forcedinductions.com/productsborgwarner.htm they say that for $189 they offer a T4 housing...This means I could purchase the 96mm 1.32unit and pay 189 on top and have a T4 housing wrapped around it...hmm...I will give them a call.

Would you guys recommend the 80mm or the 75 compressor? I am not looking to go above 700whp.

Chris

 

they are two different size turbos.. the GT47 is bigger than the s475 but the 475 will spool quicker it also depends if you are using a twin scroll setup,port work, exhaust system..


i paid $399 for a new housing + having it machine to fit my exhaust wheel of 96mm. the BW s480 with the 1.10 a/r has a smaller exhaust wheel at 83mm. the one with the 1.32 a/r has the 96mm.

http://miketurboinc.com/

that's the website.. they will make you whatever you want.

 

How is the spool with the 1.1/96mm vs the previous 1.32/96mm? How does it compare to the 1.1/83mm wheel?(if you know) And by the spool I mean, at what RPM do you start to see some boost and at what rpm do you see full boost in say...2nd or 3rd gear.

I might go this route, just buy the S475 1.32/96 and get the housing from Mike turbo...if the spool is right.

Thanks...