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Triple Webers on RB25DE is there a point?


DeusEx

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Hi guys,

 

Ive had some interest in selling my engine, and while the engine is running fine i cant help but wonder if the money could be used for another upgrade. And i got to thinking the only thing worth doing for the <5000 bracket is an RB, and i WAS looking at an Rb20DET, but alas, no one would insure me.

 

So what about an NA RB25, makes similar power to mine atm (im getting somewhere around 160 Rw HP). Is there a point in ripping off the EFI and putting on triple webers? (45's 32mm venturis) I mean, it sounds and would look failry cool, but is it a show boat thing? Its there alot involved in ridding the engine of its EFI? would the cam and timing need to be changed?

 

I did a search but could not fine anyone who has actually done it...time is running out help! :lol:

 

Thanks

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After some quick investgation i found that the RB25DE makes 96kw at the wheels. Well shy of my 110kw. So it hardly seems worth the trouble and once again i am looking towards the 2JZ GE, but the gearbox is a problem to find, and it takes abit more engineering. Triple Carb 2JZ GE? who knows, ill keep my eyes out. If only the world would insure a Turbo car....just cause some rice boy in a WRX cant handle his power and smashes into things....

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Guest bastaad525

Seriously... I dunno about YOUR insurance co., but even if my car got hit, who's going to come down and look and see what I've got under the hood? Or even know what the turbo is? As far as having your car covered for it's real value, well, if it's worth more than the blue book you would have to pay extra to cover it for whatever you think it's worth anyways, regardless if it has a turbo, or if you told them that or not.

 

 

Really, I can't think of ANY reason you need to tell your insurance co. what you have under the hood.

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Guest 240zJake
Really, I can't think of ANY reason you need to tell your insurance co. what you have under the hood.

My insurance agent is a former z owner, had to get rid of it because the wife kept getting mad at him tearing it apart in the garage...

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Nope - webers are great carbs... but throttle body injection wins hands down. As an example, two identical 3.1lt L series motors, one on 50mm webers, one on throttle body injection. The carb'd motor made 155kw at the wheels, the injection made 175kw. As for 32mm chokes, I don't believe that you can buy 32mm chokes for a 45 - 32's are the smalllest chokes for 40mm webers. However - it would be different... and probably easier to insure. Speaking of insurance... is there a policy in the world which isn't void when you have failed to disclose modifications? I've heard of someone having their insurance policy revoked because the car didn't have original wheels, and they had failed to disclose it.

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Single throttle body or individual. Oh yeah i definely have 32mm venturies. How much work is needed to convert webers to use EFI and tirn them into "individual throttle bodies" and is the change reversable?

 

yes i was thinking about a 3.1, but its alot of work and money, but hey im up for an increase from 110kw to 175kw :lol:

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It's not TBI, its sequential multi-point or whatever... injector per cylinder with one throttle body.

 

You would most likely lose power if you put carbs on the RB... the EFI system is good.

 

I don't think they would know your car was turbo, anyway...

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I think he's talking ITB's, or individual throttle bodies like this: http://www.twminduction.com/ThrottleBody/ThrottleBody-FR.html

 

The only thing similar between triples and throttle bodies is the intake manifold. Since you would have to make your own manifold, they would have absolutely nothing in common.

 

You might want to try selling the webers to offset the cost of the ITBs if you really want to do this. Just as a reminder though, John Coffey doesn't have ITB's on his 320hp NA L series. I think with a properly sized and designed intake manifold the single throttle body isn't the restriction.

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240zJake wrote "My insurance agent is a former z owner, had to get rid of it because the wife kept getting mad at him tearing it apart in the garage... "

 

If you can't even claim the garage you don't deserve a Z!

 

MY garage and my office are the only rooms I get, but those rooms are absolutley all mine and have nothing of any input by my wife. It's worked very well, but this kind of deal has to be worked out before you get married and before you own a home and every time she comes up with some "great" :roll: idea about redecorating the garage or office, you gotta be firm but true to your claim... Usually works.

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ok so i hate to sound like an idiot but yes i was thinking of ITB. Selling the carbs for EFI was my plan BUT ONLY if i can get more Hp out of it. I know some stuff about carbs, but very little about EFI. I know that ITB's look great and give you more responce but are they nessesary for Hp?

 

If i do manage to go for EFI and have $1000 to spend (say i get that for the carbs) what is a proper setup? Im not too sure what sequential multipoint is...

 

So if i get a decent size throttle body, intake plenum (custom?) i know there is a fuel rail on a manifold, but i dont know much about them, Injectors (what size? 330ci?) and a new ECU?

 

Is this more than 1k?

 

Would i be better off starting from scratch or using a 280ZX platform?

 

Thanks guys, hope i didnt ask too many stupid questions

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Why not just use the stock intake manifold (maybe port it a bit) and run an aftermarket computer? I haven't looked into this too far, but that would be my best suggestion for building on a budget.

 

Something like a Megasquirt N Spark or something, then all you need is a custom header for the exhaust and whatever sensors are necessary for the intake.

 

BTW are you SURE that you have 45 mm Webers with 32mm venturis? You measured the holes on the MANIFOLD side of the carburetors, right??? The carb throat has a bell shape to it and the holes are larger on the air horn side than the intake manifold side.

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I think he's talking ITB's' date=' or individual throttle bodies like this: [url']http://www.twminduction.com/ThrottleBody/ThrottleBody-FR.html[/url]

 

The only thing similar between triples and throttle bodies is the intake manifold. Since you would have to make your own manifold, they would have absolutely nothing in common.

 

You might want to try selling the webers to offset the cost of the ITBs if you really want to do this. Just as a reminder though, John Coffey doesn't have ITB's on his 320hp NA L series. I think with a properly sized and designed intake manifold the single throttle body isn't the restriction.

 

Yep - I meant individual throttle bodies, based on the weber pattern... but in the case of the 175Kw @ wheels, the throttle bodies were custom fabricated and spaced so they gave a straight shot down the inlet port. Nice piece of work.

 

Anyway - tell us more about this 320Hp NA motor! I checked out his web site, and no mention of specifics, and a search of the forums didn't get me anywhere either. Is this a roadrace or drag motor?

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I've seen a few RBs converted to triple sidedraught carbs in Japan, usually performed by ROCKY AUTO down in Kyushu.

 

With modern electronics controlling sparks, as long as the carbs are jetted correctly they seem to run just fine.

 

When installed in an early body ( usually S30-series Z, and C10 or C110-series Skylines ) these carbed RB conversions have something that is often forgotten with all the talk of high horsepower etc - and that's flavour. It doesn't need to be hugely powered to be fun, and the donor engines can be had for a song in Japan - so why not? Its fun.

 

Here's a couple of pics of carbed RBs in an S30-series Z and a C10-series Skyline that I took last year:

 

http://alan-t.fotopic.net/p9592248.html

http://alan-t.fotopic.net/p9592249.html

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Anyway - tell us more about this 320Hp NA motor! I checked out his web site, and no mention of specifics, and a search of the forums didn't get me anywhere either. Is this a roadrace or drag motor?

 

Go here: http://www.betamotorsports.com/products/index.html and click on Stuff for Sale, then click on Sunbelt 320 hp Nissan 3L engine.

 

Very impressive. Wish I had the $$$...

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