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Rb26- Enlarging Std Throttle Bodies

XRATED

By XRATED,
in Engines & Forced Induction

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LaurelPWR
LaurelPWR

Hey mate, thread dredging hahah To answer you directly, yes I had my itbs oversized and custom butterflies etc made by EFI Hardware in Sydney back around 2017-2018 if memory serves. My setup

ed_ma61
ed_ma61

really? wow, i didnt know my engine had such problems!?! thanks for the heads up, ill go remove them now

Piggaz
Piggaz

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s2d4 Rising Star

s2d4

Posted
Posted

Awesome questions and answers in this thread.

XRATED, If you don't mind me asking (since I have a habit of asking you things), Which plenum are you using?

I am also be very interested in your quest of the perfect seal with your set up as I would imagine the response should improve, as well as higher power/torque figures.

XRATED Veteran

XRATED

Posted
  • Author
Posted
Awesome questions and answers in this thread.

XRATED, If you don't mind me asking (since I have a habit of asking you things), Which plenum are you using?

I am also be very interested in your quest of the perfect seal with your set up as I would imagine the response should improve, as well as higher power/torque figures.

... ha ha ha no worries mate.

As posted previously, I have a two piece Greddy RB26 plenum.

There are a few 'secret' and not so secret tricks to get tb's to seal... most are well covered in the forum.

There should be some gains... well I hope so! But more top end is not my goal.

J.

ARTZ Grand Master

ARTZ

Posted
Posted
EFI Hardware can do them 0398735400.

Cheers..

Depending on price ,I might give it a go for the fun of it..i cant see how it could hinder performance at all, seems like it would aid flow if anything even if only marginally more responsive. Measuring the stock TB front is 65mm rear is 60 so there is at least 5 mill to be had plus smoothing out the butterfly has got to let it flow better than original...Doesnt it?

I have seen it done once before on a honda ,and it definately didnt make it any worse...

Ill report back with my 50kw gains later... :)

PS

Man i did a search on this the other day and nothing came up so i started a thread...fuggin..

XRATED Veteran

XRATED

Posted
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Posted (edited)
Cheers..

Depending on price ,I might give it a go for the fun of it..i cant see how it could hinder performance at all, seems like it would aid flow if anything even if only marginally more responsive. Measuring the stock TB front is 65mm rear is 60 so there is at least 5 mill to be had plus smoothing out the butterfly has got to let it flow better than original...Doesnt it?

I have seen it done once before on a honda ,and it definately didnt make it any worse...

Ill report back with my 50kw gains later... :)

PS

Man i did a search on this the other day and nothing came up so i started a thread...fuggin..

I did ALOT of reaserch and ALOT of calculations before I had a set of tb's modded.

If you dont have the propper head work and plenum volume mods... you will more than likely go backwards. Or best case not gain anything except a bill from EFI Hardware. Not to mention that you have to permanently modifly your injector/joining manifold and plenum runners to suit... so add another $300 for machine work and $500 for a new plenum, tb's and joining manifold when/if it dosen't work....

I recently had a conversation with a Jenvey rep... they seriously looked at producing an rb26 itb set up and manifold. They couldn't gain much anywhere in the power range OR in response/progression whith they're designs and throttle bodies.... They modelled everything on a simulation program- so nothing was actually built. The only gains they did get was with particular flow rates, with particular variables and a slight increase in tb diameter (49mm). For those who don't know who Jenvey are google it- they're one of the best multiple tb designers/manufactures in the world.

The money is better spent somwhere else... Like nitrous ah ah ah.

Cheers

Justin

Edited by XRATED
Mattw_83 Community Regular

Mattw_83

Posted
Posted
Getting a normal single throttle body is an expensive enough operation. I cant imagine what it would cost to have 6 throttles done at once. I think it might be easier to modify the base plate, weld and match port it to some aftermarket IDF/IDA/DRLA throttles. Injection Perfection does some really nice throttle with trumpets, which you could then build a custom plenum around. Ive seen then in 48, 50mm and larger. Extremely nice quality.

The other options are to have the throttle shafts profiled, or change to these fancy looking things.

http://www.gtr.co.uk/forum/106680-shaftles...s-rb26dett.html

Thatsbloodsport clip is the funniest f**kin thing ive seen in ages..

ARTZ Grand Master

ARTZ

Posted
Posted

Yeah,Rang those guys, its about 250+ for my single, so f**k that..too much for too little..at half the price i may of considered it..research is good in theory, but nothing beats trying it...And ive seen people do it with ok results, But not on skylines..

rob82 Mentor

rob82

Posted
Posted
... ha ha ha no worries mate.

As posted previously, I have a two piece Greddy RB26 plenum.

There are a few 'secret' and not so secret tricks to get tb's to seal... most are well covered in the forum.

There should be some gains... well I hope so! But more top end is not my goal.

J.

I think your being quite ambitious if the goal is not for more top end. I've also done alot of R&D on intake manifold design mostly on aspirated engines but I have tested varible runner length intake manifolds in turbo charged engines with good bottom end turbo responses found (upto 500rpm better spool rates). I've also been involved with the beautiful FR500 intake manifold on both 4.6L and stroke 5.4L modular V8's with various mods.

In alot of boosted applications I've never noticed any tangiable gains in upgrading to larger diameter throttle bodies. I can give you two scenerios that may surprise you:

1. HTV2300 boosted LS1 wih all the fruit - the client wanted a MAFLESS tune in order to get rid of the 78mm MAF and ultise the 90mm throttle body and intake. THe vehicle had previously made 410rwkw with the std MAF, in 4 hours of tuning I didn't see a sigle gain in horsepower at any rpm. It also didn't loose any power.

2. In some XR6T's once the exhuast and Intercooler have been upgraded along with fuel system the vehicles have a tendance to over boost due to the 32mm wastegate port. In these situations I reduce the throttle opening to control the boost. I can tell you that in some situations I have remduced throttle openings to 40% total opening without any loss in horsepower and this is up around the 360rwkw mark with the std(72mm??) throttle body.

I dont know your current setup but a change in runner length may warrant more gain in response and midrange power without a loss in topend power. Note that I'm not discrediting proper port matching as ruducing turbulance in the port can really help.

  • 1 year later...
LotusGTR Veteran

LotusGTR

Posted
Posted

Can anyone contributing to this thread assist with my somewhat related question? Thanks guys.

http://www.skylinesaustralia.com/forums/topic/376280-high-idle/page__p__6001309__fromsearch__1#entry6001309

  • 4 years later...
Chris32R Proficient

Chris32R

Posted
Posted

Sorry to hear bud. Hopefully karma gets the assholes.

I'm looking at getting my set enlarged soon too. Is there anyone other than efi hardware able o get this done for cheaper? Over $800 with postage each way send a bit steep.

  • 7 months later...
Piggaz Grand Master

Piggaz

Posted
Posted
37 minutes ago, eXquiSit said:

Tbh it would be cool if hypertune or plazmaman made larger billet throttles then also one of their plenums to suit the larger throttles

I would buy that!

 

IMG_1079.PNG

  • Like 1
  • 4 weeks later...
  • 2 months later...
  • 7 years later...
Predator1 Rising Star

Predator1

Posted
Posted

bump.

Anyone had this done? either 49 or 50mm? Been pondering what to do while mines in storage. Been thinking of DBW but if I do that, then might as well do this too. Want to retain 6 throttles.

I have a fully build head(CNC, OS valves, 286/278 cams, etc etc still running squish), and a Greddy old school intake with port matching.

Head bench flowed 300cfm. Wondering whether bigger throttles will give me any gains. Makes 563kw.

joshuaho96 Veteran

joshuaho96

Posted
Posted
30 minutes ago, Predator1 said:

bump.

Anyone had this done? either 49 or 50mm? Been pondering what to do while mines in storage. Been thinking of DBW but if I do that, then might as well do this too. Want to retain 6 throttles.

I have a fully build head(CNC, OS valves, 286/278 cams, etc etc still running squish), and a Greddy old school intake with port matching.

Head bench flowed 300cfm. Wondering whether bigger throttles will give me any gains. Makes 563kw.

https://www.gtrusablog.com/2020/03/itb-vs-single-throttle-individual.html

 From the math here and some real world dyno comparisons against a 102mm throttle I doubt it’s worth the effort and expense. 
 

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