big power no lag?

[midnightsliding]

just wondering i did a search but i couldnt find the info that i needed, or maybe im a dumbass and cant use a computer but anyways, i was wondering what a good turbo set up would be for the RB25Det. i want to make around 450rwhp ish. what turbo would i need (exc. like Trim and A.R) and what PSI. i found some info about RB20 ake like 380ish on 20 PSI but their full boost was like 5300rpm i want something that has more midrange to top end power . is this possible? thanks for any info you guys provide me with.thankswes.

[T4 RB25det]

your going to be kinda hard pressed to hit 450 with a non laggy turbo without running alot of boost. im running a t4 gerrett gt35r with 1.04 hotside, to4r compressor side, and q trim wheel. hitting full boost around 5,000 rpm

[Yellow4g63]

You could use nos to spool the turbo faster

[Carl H]

You could use nos to spool the turbo faster

heh, whats a bit of laughing gas between friends.but yeah to make that much hp you are going to need a fairly large turbo to do so, and that means lag any way you cut it.if you want quick spooling 300whp easy slap on a hks gt2530r proven to be excelent on spool and power on the rb20.

[rbsileighty]

For what you want... I'd say a new intake mani and cams are a must (mid-top range power... I hear pistons should be included on a 25... might drop the CR a bit while you're doing those... wouldn't be a bad idea)...

as far as turbo... I'd say run a 35R w/ a 82mm wheel since it has such an eff map for what you want at only 1bar boost...

With the flow output req from the 25... I might suggest a .82 or maybe a .63... testing would show best (backpressure testing would be the way to know for sure)

Don't skimp on a dump pipe as the change in pressure across the turbine is vital for eff... so lowest restriction possible... few bends... straight and big

Don't underestimate cams and the intake manifold... you can throw whatever you want on there all day long, but with a long runner manifold and stock cams your peak power will stay at the RPM range it is... might grow... but remember the equation for HP... function of RPM and TQ... RPM goes up.... so does power

Might consider pistons with a higher power 25... just a note

hope this helps

[Nameless EJ6]

Instead of asking what turbo you "need".. try asking what we recommend.

Just a thought, because personally, I don't do other peoples homework when it comes to upgrading.

Try the skyline forums.

http://www.skylinesaustralia.comhttp:// ... nunder.com

.. I seem to find more information on those forums than any US based resource forum. Esp with RB's. Now SR.. you'll find good info almost anywhere.

Sorry I couldn't help with your specific Q. I'd go with an HKS or garrett compressor tho.

[midnightsliding]

thanks for all the info guys, im looking for big power b/c its going in a big heavy car. but 450 itsnt that big i jsut want something somewhat responsive and not have to beat it of rev limiter to keep it in the power band. i know jspec sell an intake manifold for the RB for like 680ish, what cams would u guys recomend? thankswes

[Andrew85cm]

When I first read the heading "big power no lag" I kind of chuckled to myself because in order to have big power you are going to have lag. In order to get 450 hp out of that rb25 at a reasonably low boost pressure, ie less than 20, you will need a decently large turbo such as a gt35r as stated above. This is a pretty big turbo and will be a bit laggy but will easily get you to your power goals without trashing your head from running so much boost pressure. The dual ball bearing factor will be helpful in responce but I would imagine you wont see full boost til about 4500-5000 either way. I would say cams are a must for you to have a nice top end that won't die off on you. What is this motor going into that is so heavy?~ANDREW~

[rbsileighty]

256's or 260's seem to be popular with the guys on the AU board... don't forget cam gears since you'll need to degree them. I could run some calculations for you if you can get runner length, area and plenum volume values to me just to make sure this puts power where you want it.

Carl's running 260's I think... might ask him how it idles to see if that's something you want.

Don't forget pistons... look up a guy named Fito on this board and you'll see why.

What's your budget by the way?

Ok... well I was interested myself so I guess I saved you the time... have to help out a fellow North Carolinian anyhow

zerothread?id=48748

zerothread?id=54405

I still think the GT35R is the right turbo for you vs his setup... quick calculations put you at 1bar at or just below 4000.

You can see in those posts how pistons are a good idea. Another option would be to run a full GTR bottom end (stock crank/rods/pistons) since they should hold up to what you want to throw at it and more. Might cost less since they are stock equip...


Modified by rbsileighty at 11:06 AM 9/21/2005

[T4 RB25det]

yeah as stated its going to be even harder to get to 450 on stock IM and stock cams. Cams wont help your spool, but much more top end. Intake manifold could cause more lag, but more top end. better exaust manifold will help spool since the stock one flows like ***. other things like size of intercooler core, intercooler piping, throttle body diameter, exhaust piping diameter will effect spool time as well

[midnightsliding]

money might not be a big porblem i have none right now but im planing on coming home with alot. im wanting to run power FC is this alright for the RB25?i want this done right, and i know the rings re the weak pont on the RB25, same as the KA24. and im wanting to run the HKS bottom mount turbo and exhaust i will make a streight as possible 3.5 DP ,test pipe, and cat back. the only thing im worried about right now is fitement issues in the car that i want to put it in. and as far as idles not a big isue with me as long as it dosent drop off too much and cut off. RB sileighty jsut a ? what part of NC are u from i live in winston-salem.(kernersville) iv meet carl H about a year ago right when he got his new s14.thanks guys for all the info.

[Wulfgang]

Aren't you the guy with the Q45? And you're asking about big power and low lag (I assume you probably mean low boost threshold rather than low lag)?

So, as others have said, anything you do to the RB25 to increase it's power will also increase boost threshold with 3 exceptions: 1) increase displacement, 2) use ball-bearing turbo, 3) raise compression ratio.

But you already have an all-aluminum 4.5L V8 under the hood with high compression, probably already making around 300 hp. Just put a pair of turbos on it. You won't need much boost at all, so you won't need to build up the engine. Even on a bone stock Q45, 7 psi could put you at 450 hp right there.

[midnightsliding]

Aren't you the guy with the Q45? And you're asking about big power and low lag (I assume you probably mean low boost threshold rather than low lag)?

So, as others have said, anything you do to the RB25 to increase it's power will also increase boost threshold with 3 exceptions: 1) increase displacement, 2) use ball-bearing turbo, 3) raise compression ratio.

But you already have an all-aluminum 4.5L V8 under the hood with high compression, probably already making around 300 hp. Just put a pair of turbos on it. You won't need much boost at all, so you won't need to build up the engine. Even on a bone stock Q45, 7 psi could put you at 450 hp right there.

Q45 yes. i want to do any RB just b/c its different and the Q im geting dosnt have an engine, but i want to make its like a crazy hybrid, i dunno y, jsut want to be different, and i would rather use a turbo engine from the factory, and fabing up a kit for the 4.5 would be too much work for me.(just kiding but that my excuse) and im wanting to drift the Q so i want somthing that i can beat on and it take it, theirs not a lot of info on the 4.5. plus i have always have this love for RBs and 4 doors so i want to put it together and have a desecint car. i love the s13 but its been trough alot and i want a new project. look that the feed back that i get when i ask a question in the RB fourm, if i asked this in the Q section they would be like wtf its a luxray car y would u want to do that. and i think everyone for giveign me all this great info.

[Wulfgang]

theirs not a lot of info on the 4.5.

And wouldn't that make doing a turbo Q45 something "different?" Besides, what info do you need? Adding 7 psi of boost is sooooo easy. KA people do it all the time. The only major issue with the V8 would be plumbing.

Don't get me wrong, I like RB's too. But the Q45 has 80% more displacement. That's almost twice as much horsepower on otherwise equal engines. And although the RB is claimed to be "race bread", the Q45 shares blocks, bores, valves, etc. with a real-live Indy car engine.

There is also the $$$. Q45 would be cheaper, hands-down.

Do it. I want to see this thing pull up trees by the roots when you're finished.

[SeVa-S13]

JGS Tools custom log manifolds, twin T3/T04E's (maybe .48 vs .63 if you really need super low threshhold), some headwork and custom ground cams to offer a little better power up high. Mate it to the Z32 5spd box and destroy all...but that's not as cool as having the same engine and setup as 100's of other people, but in a different car, right?

[midnightsliding]

.but that's not as cool as having the same engine and setup as 100's of other people, but in a different car, right?

i would rather knock some else's set up and make a dicent amont of power and have the same engine that many other ppl already know i dont want to be a pioneer of the 4.5 or the rb i jsut know ppl make good power on the RB and they can handle the abuse. i dont wnat to dumb money into the 4.5 and be pissed when somthing****s up on it. and dont compare its to the KA b/c i have blown 5 bone stock KAs in under a year 1/2,( non of the engine had over 60K on them except one and its lasted the longest for sme reason.) so im not looking to sawp the 4.5 out liek i already have in the s13, plus once agine the car im looking to buy has no engine so their for i would alridy have to dump out like 3grand on a stock used engine. and the fab up the twin turbo kit, and find a z32 gear box. and then i would have the worrie about it poping.( i also worrie about the RB blowing too, dotn get me wrong) i jsut dont like the idea of turboing a NA engine , i had a 96 GSX and i was making 293 hp in that and i raged the piss out of it took the beating and even the i was runing the 7bolt engine and i had to worrie about crank walk. i dont know im not going to force u to like it u can falme me all you wont i dont really care but im not saying anything about the 4.5 i really dont have a clue could be the best engine in the world i dont know i havent even touched one much less drove one.

[Carl H]

how did you blow 5 ka motors in that span of time?im willing to bet it was due to improper warm up and driving an engine hard when cold.when i got my s14 i drove the everliving **** out of it and then sold the still insanley good engine to a friend, and he hasnt had a problem since.i think the vh45de gone tt is the best way to go, its in there, no harness swap and you can mate it to the z32 trans with some love.......

[midnightsliding]

the KA has such a long strock, keeping it in the high reves wars them out much faster haha, anyone ever snaped two conecting rods. this engine had right arond 85K on it. ^ look near the engine mount on this side.WTF and i took care of them i use good oil filters and castrol 20w50 and they all got changed ever 2500mile intverals.

[SeVa-S13]

i would rather knock some else's set up and make a dicent amont of power and have the same engine that many other ppl already know i dont want to be a pioneer of the 4.5 or the rb i jsut know ppl make good power on the RB and they can handle the abuse. i dont wnat to dumb money into the 4.5 and be pissed when somthing****s up on it. and dont compare its to the KA b/c i have blown 5 bone stock KAs in under a year 1/2,( non of the engine had over 60K on them except one and its lasted the longest for sme reason.) so im not looking to sawp the 4.5 out liek i already have in the s13, plus once agine the car im looking to buy has no engine so their for i would alridy have to dump out like 3grand on a stock used engine. and the fab up the twin turbo kit, and find a z32 gear box. and then i would have the worrie about it poping.( i also worrie about the RB blowing too, dotn get me wrong) i jsut dont like the idea of turboing a NA engine , i had a 96 GSX and i was making 293 hp in that and i raged the piss out of it took the beating and even the i was runing the 7bolt engine and i had to worrie about crank walk. i dont know im not going to force u to like it u can falme me all you wont i dont really care but im not saying anything about the 4.5 i really dont have a clue could be the best engine in the world i dont know i havent even touched one much less drove one.

I'm sorry but I can't really read that. I'm also not trying to flame you, just giving you another idea. And HOW THE HELL did you blow 5 KA's? You must realize that's the driver, not the engine, right?

[T4 RB25det]

heres a pic of the turbo i am running to give you an idia of the size needed to make the power you want

[midnightsliding]

its like i said im not ur average driver. all i do is work and go drive, and i never looked into upgrade b/c a stock KA felt nice, kinda like a AE86 ( no power jsut beat the piss out of it.) i jsut keep them in the high revs im not sdowing the KA i love it sitll have it and plan on keeping it. my car had 58***mile on the car when i bought its about 2 years ago and not its about to hit 195***miles so im not ur average drive im always in the car driving.

[Wulfgang]

ANY engine, whether KA, RB, VH, NASCAR, or F1, will blow up if you over-rev it. So NO, the RB can't "handle the abuse" as you said. Nothing can. A cast-iron block may handle more boost than an aluminum block, but over-revving it will destroy the rods all the same.

And you are correct. You are not an average driver. The average driver knows that the little red strip on the tach means either upshift or get your foot off the gas.

[Carl H]

exactly.......course since i redline at 8 i have to go past the red.......anyways the only time ive seen a ka eat rods and bearings is when the motor is driven hard when cold, ive got a buddy with a crazy kat and he revs that crap out to 7k all day without a problem and has done so for the past 3 years........

abit OT:t4 rb25det - that looks an awful lot like a rb20 and not a rb25.........whats goin on here?

[Kansei240sx]

That is a 20....... wtf?

[T4 RB25det]

That is a 20....... wtf?

valve covers, coil pack, and ignitor got fubared during shipment. the only things i could get were from an rb20. but they didnt fit all the way down. thats why there is the welded hump on them. Block code says rb25 tho. It has also been converted to top feed injectors

[SeVa-S13]

The intake cam gear and fuel rail seem...off. (20)

[krayton]

valve covers, coil pack, and ignitor got fubared during shipment. the only things i could get were from an rb20. but they didnt fit all the way down. thats why there is the welded hump on them. Block code says rb25 tho. It has also been converted to top feed injectors

haha that looks awesome. really does look like a rb20 wanting to be a rb25. but nice work. sure once u clean it up and throw some paint, itll look good.

[T4 RB25det]

yeah the

The intake cam gear and fuel rail seem...off. (20)

yeah, it is converted to top feed injector. i am running adjustable cam gears, that pic was taken when i was putting the IM, fuel rail, new turbo, cam gears, cams, new turbo mani, and some other random ****. i was in the process of removing the cam gears at the time, thats why the vvt sensor thing isnt on anymore, also why the timing belt cover is off if it bothers you that much i can get you a pic of the block code

[gawdzilla]

heres a pic of the turbo i am running to give you an idia of the size needed to make the power you want

nice custom work, way to work with what you had. is that the SSA manifold? did you do anything to beef it up or support it? hows it holding up?

[T4 RB25det]

its a manifold from thialand. i had origonaly bought the ssa mani because its the only one i could find. but my freind who is from thailand said he could get me one much better, and would come in a t4 flange instead of me having to weld a new flange on the already flimsy ssac mani. looks the same, but it weighs about 4x as much. that pic is kinda old, but yes i did support it. holding up great for me