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ok ive been lookin into buying an upgraded turbo for my rex and still have no clue. Which ones the best with the least amount of lag and that will give me alot of hp and tq. i know the bigger they are the more lag u get but so many turbos and so little data on any like; greddy, hks,vfseries,avo,peseries,16g 17g 18g or 20g. i probably missed some but i want a direct replacement that will give me the best performance at a reasonable price. i guess im more concernced about getting more power with least amount of lag. please help me out, i have searched on this site i-club, noaic, and others but have really not found any real good numbers from these turbos. gabe
 

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The VF34 spools very nicely i hear.
 

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Yeah at a good price I would go with the vf30 or vf34 they both have good spool up under 3000 the diff is the vf 30 spool a tad bit slower with more top evd than the 34 both the both still spool fastet than the vf22 either way your be increasing your top end. I would like to add that both still fall off a little near redline and I think you should concider spending the extra money on a PE1818 for very good spool up the the best top end out of the 3 and it pull hard till redline and beyond..

FF
 

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I thought the PE's didn't spool until well after stock times...
 

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They don't but the pe1818 spool up farely quicker than the pe1820 which does't hit max boost till 4000 rpms.

FF
 

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Here's the physics controlling this situation...

Bigger mass requires more force to move.

Therefore, the bigger the turbo, the more exhaust pressure you have to produce before it starts moving.

So, you have to decide how you want this car to respond. Do you want it to be quick off the line? Or do you want it to have a deep top end? Bigger turbos mean slower spool up. Smaller turbos mean quicker spool up but less power at the top. Choose your poison.
 

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but, is there a way to have both worlds? Maybe dual turbo, one lightweight for fast spool in low end and a heavier one for high end? Does anyone know of a larger turbo made from lightweight material such as titanium innards? This would allow it to spool faster yet retain high end boost... just a thought
 

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There's a good sticky at the top thats got flow rates for many different turbo's. Check that out to see which one will fit you best.

IMO, the vf30 or vf34 will fit most people's need for a larger turbo. The PE1818 is a reworked turbo with much better internals, but you'll pay a lot more. Depends how much you wanna spend...
 

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The VF30 does NOT have full boost at 3000, more like 4000. The VF35 and VF34 have better spool up but obviously more expensive. The VF35 is smaller but of course no top end power. The VF34 a little bigger, not bad power but still dies out at high RPM. The PE1818F has about same lag as VF30 but HUGE increase in top end power over the VF series. Not too much ore than a VF34 and full ball bearing on both the turbine and the compressor unlike the VF34.
 

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Why is the vf34 is only ball bearing on one side? I learned that recently and Im trying to understand why... why isn't both sides ball bearing? Anyone have any insight into this?

I have to agree that my vf30 really starts to spool a little under 3000 and full boost at around 3600-3800.
 

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MY Bust !!!

I should have more clearly stated that the start to boost at or around 3000 RPM'S... Sorry

FF
 

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hey there

hey,
my wrx is the first turbo car I have owned, but from what I know even the slow spooling turbos on a wrx don't spool so slow compared to other turbo driven cars. We must get spoiled because of it. I really don't think that lag is an issue cause once you build up your boost in the gear you start in, you're set. I think that with turbos, the issue is more of how much horespower you are going for.

In general, the quicker a turbo spools up, the less efficient it will be at higher boost levels which limits the amount of boost that you can run. If you get a really quick spooling turbo and run 22psi of boost, the air will probably get so hot that you will melt your pistons. Also your turbo will get really hot (compared to normal)from working harder than it was ment to.

like I said in th other posts about turbos on here, I like the avspec sr40. To me it seems like the most efficient turbo for a moderately tuned wrx(wrx withought new pistons and such).
 

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Re: hey there

hippy78 said:
but from what I know even the slow spooling turbos on a wrx don't spool so slow compared to other turbo driven cars. We must get spoiled because of it.

Where does everyone hear this from?
My Mom's old turbo Volvo = Same spool as the WRX
1.8T VW/Audi = way faster spool than the WRX
2.7T Audi S4 = a little faster spool than the WRX
2L DSM's running all kinds of different turbos = consistently spool 500 rpm faster than a WRX with the same turbo/supporting mods

Why does everyone say the WRX spools so fast? I honestly don't think it does! Perhaps compared to a T78 equipped Supra, yeah, but otherwise I think the only WRX that can be called "quick spooling" is a stage 2 one:(

Sorry, I'm just pissy cause a V8 firebird got the jump on me today with his incredible 'no-spool' ability while I was caught in too high a gear ;) I'll be quiet now
 

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hey

sorta sucks when you can't go faster than a car you know you can beat. maybe it's the way you drive and not how quick your turbo spools:). My point was that if you are in the right gear, you get past the lag in about 2 seconds, and you are set til you wanna slow down.
 

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Re: hey there

hippy78 said:
but from what I know even the slow spooling turbos on a wrx don't spool so slow compared to other turbo driven cars. We must get spoiled because of it. I really don't think that lag is an issue cause once you build up your boost in the gear you start in, you're set. I think that with turbos, the issue is more of how much horespower you are going for.
you are correct. but remember, as for streetability, more lag = less comfort. you said it, the rex has almost no lag as fas as the rest of the turbo world goes. in contrast, it also has a pretty standard redline, so not hitting full boost till 4000+ rpms, means you're eliminating the fun from 2/3 of the gearing.

dR
 

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God said:
The VF30 does NOT have full boost at 3000, more like 4000. The VF35 and VF34 have better spool up but obviously more expensive. The VF35 is smaller but of course no top end power. The VF34 a little bigger, not bad power but still dies out at high RPM. The PE1818F has about same lag as VF30 but HUGE increase in top end power over the VF series. Not too much ore than a VF34 and full ball bearing on both the turbine and the compressor unlike the VF34.
Dan, I'm sorry, but we both know this depends largely on exhaust. My VF30 is at full boost by 3500rpm. If you are catted and muffled, you can expect less perform from any turbo.

As we always say, if you don't like lag, save the headaches and keep the stocker.

-Jim
 

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hey

how long it takes for any turbo to get to full boost depends on many many things. The most important in my mind would be the exhaust and intake like ^he said. Then the boost controller, if you have a car that is tuned conservatively for reliability it will obviously spool up slower than a car running 100percent solonoid duty cycle til you hit full boost.

I have a vf34, and lotsa people tell me it takes til 4000 to get full boost. I am running a utec engine management at 30 boost gain(which is something like 70 percent from what I know). If I start in 3rd gear at 2000rpm, by 3000 I have full boost. If I shift when I get to full boost, in fourth I get full boost by 2700.

I am not saying that is how to drive fast, because it it's, but it shows that you can set the boost gain to 1 instead of 30 and get better spool up results(higher boost at lower rpms)....not that it would necesarily make your car go faster. I mean, if you wanna get boost quick, and your movin you just downshift so your boost builds up quick and you have more power at high rpms, then within a second you are past the lag pount and the turbo just starts building boost consist

The only time that lag is really an issue is when you wanna go really fast from a dead stop and don't wanna ruin your tranny or clutch. I never wanna go so fast that I am willing to screw up my car intentionally and that is what I think people do by droppin the clutch at 6000rpm on a stock tranny and clutch.

Also, if you start off from a dead stop, you just have to wait till about 3000 for the boost to push you past the other car. Even if you aren't at full boost, the building up of the boost gives you a lot of power in first gear, and the only reason the boost meter doesn't read full boost in first is cause there is less thermal density in lower gears. That means that the turbo actually has to flow more air to get the same boost in boost in first gear as it does in 3rd.

I really don't see lag as being a problem, like I said, most people don't make quick spooling turbos spool up as quick as they can unless they are racing. The same is with bigger turbos, so if you bump up the boost gain on a bigger turbo, you will get good enough spooling results in my opinion.

Like I said b4, it's all about how much power you want, and how conservatively you want to achieve that power.
 

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I have a friend in Japan who has put together a one of a kind turbo. IHI RH5FH VF38, titanium turbo.. It came with a twin scroll housing, and he changed it to a single scroll housing for wrx. The housing is not even for sale anywhere. He got it through a contact at Subaru. Anyone interested?
 
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