Does the IHI have the same lag as a standard turbo?

[virdi]

Hi all,

I understand that the IHI Turbo used in the popluar BT conversions... is Roller Bearing type.

So from what I've been told - Roller Bearing Turbo's don't hardly have any lag.... as they're sposed to spin up very quick etc...? is this true?

So... What I'm trying to get at is... if I went IHI would I get more or less lag than the standard setup in my LCR?

Thanks

 

[Saul]

moved, funnily enough, to big turbo discussion

in answer to your question, yes slightly more lag, its a bigger turbo with a larger capacity, so will take longer to reach full boost compared to the smaller k04

 

[paul26982]

i thought they wernt as laggy, more bottom end than top

 

[minimivic]

IMHO Lags a funny word really.

The way I see it is: a standard car is designed to be smooth and efficient. So when we go big turbo do we really care if the car is as smooth and efficient. Lag is really only relevant when accelerating (using the same gear) so why not just change down a gear and let the revs overcome the lag for us? That what most do anyway when wanting power to overtake. What I mean is if a turbo produces good boost at 3500rpm then don't plant the throttle at 2000rpm and expect it to do anything.
Also if you go BT the car can be driven off boost most of the time making it more efficient on fuel. Its similar to my VTEC mini under 6k and its a normal car above 6k its a race car so most of the time its returning 35mpg but when driven hard it goes down to around 20mpg.

Sorry its a little off topic but I feel its relevant.

Just off to put the flame suit on, but open to discussion.

 

[Feel]

I'm very interested in this. I think that what you're describing is "boost threshold" rather than "lag". Correct me if I'm wrong.

I'd be interested in seeing, somehow, how the different big turbos compare when it comes to the boost onset, i.e. when they start spooling and when they're fully spooled.

Reading between the lines, Vic (?) says, perhaps this is only really relevant on a road car - but that's what I drive

I know that one thing I love about my K04/LCR is how the boost is there from about 3,000 onwards, making 6th gear heavenly, and while more top-end would be nice, I wouldn't what to compromise too much on this boost response.

I've never really seen any graphs/figures/whatever that compare, say (Please shout up if I've these specs if I've got these names wrong):

GT2X Eliminator (280bhp)
GTRS Eliminator (340-360bhp)
GT28RS .62 (340bhp)
GT2871RS (360bhp)
IHI VF34 p18? (320bhp)
IHI VF34 p20 (335bhp)

I know the IHI Boys (VF34 p18) have often said that it spools like K04-023, and while it might "Only" have 320bhp top end, it's probably a better choice, on the road, than a GT2871RS.

I also know that the IHI boys have said in the past that you can sit in top gear (5th for most of them) off-boost and pootle along (60-80) getting, probably, better MPG than a K04-023, where at the same speed, you're on/off boost...

Does anyone have any comment?

 

[ibizacupra]

you will be pulling well from mid 3K rpms on VF34..... and continue to pull more and more to >7Krpm

not as in ya face torue delivery as a chipped k04 would be, and less bottom (sub 3K) punchy, but different league...

and then there's mitsi based turbo's like I have evolved onto these days, which makes vf34 seem like a wheezy k03. 4K onwards manic pull to >8Krpm (but this is for serious modders only, and mandatory internal mods req'd)


cruising on VF34 was as economical if not better when off boost. Normal side effect of mapping anyhows.

 

[Madmile]

I reckon vf34 running quite hard like mine used to 330bhp and a .20 housing version would be 340 ish bhp. The fun does not really start until a genuine 375bhp+ has been achieved maybe even 400bhp+.

 

[ibizacupra]

or even 500bhp..... coming soon to an ibiza somewhere close to me real soon.

how daft is that!

nutts

 

[Madmile]

As a track car when its on the boil all the time its very important. I still think for someone looking for a good road going setup the old Pe1820f had a lot going for it in the 380-390bhp region. Its only what i feel not what i know though.

 

[jonathanp]

bill how does yours compare to the VF34 or K04? Is it a TD unit you're using?

reason I ask is that i've wondered what spool up would be like on a smaller version of your turbo set up to produce around 400bhp at 7-8k rpm

 

[Feel]

Updated my post, but you've quoted me

Where does the p20 spool then? Scotch John seems happy with his, says it's about 3500-4000.

You're all certifiable. 375bhp in a front wheel drive car and traction must be a real problem (even mine can be a handful), 4wd and I bet clutches get a hard time. You can't win.

"I'd be happy with 320-340 ish"* with some decent useability.

*I bet every one of the BT Boys has said that a least once before....

 

[ibizacupra]

As a track car when its on the boil all the time its very important. I still think for someone looking for a good road going setup the old Pe1820f had a lot going for it in the 380-390bhp region. Its only what i feel not what i know though.

not just a track car gary. (there's another road car being built to same spec shortly)
its every bit as drivable as the PE before it with almost no difference in when power starts to pull strong.
sub 4K its slower, but thats only cos its daft as a brush when its up at 4K and beyond.... (off gauge boost from 4K if you want)-30psi gauge and its been pegged to a datalogged 37psi (sensor max). - completely silly levels I would not advise, but when it goes, by christ it goes... I have 10-12psi available from 3500rpm and off gauge from 4Krpm

in fwd its... as you would expect.... traction limited, but no worse (possibly better than PE) as its torque delivery is less aggressive but more sustained. (flat)

PE was working hard to get the high 300 numbers on the JS mani...setup of before.

I changed my mani an turbo so its a combination of parts which give the results, so spool on mine is maybe better due to equal length, but flow ability is massive.

 

[ibizacupra]

Updated my post, but you've quoted me

Where does the p20 spool then? Scotch John seems happy with his, says it's about 3500-4000.

You're all certifiable. 375bhp in a front wheel drive car and traction must be a real problem (even mine can be a handful), 4wd and I bet clutches get a hard time. You can't win.

"I'd be happy with 320-340 ish"* with some decent useability.

*I bet every one of the BT Boys has said that a least once before....

P20 did'nt make much difference to spool.... and side by side you will struggle to see much difference between em.

 

[Madmile]

not just a track car gary. (there's another road car being built to same spec shortly)
its every bit as drivable as the PE before it with almost no difference in when power starts to pull strong.
sub 4K its slower, but thats only cos its daft as a brush when its up at 4K and beyond.... (off gauge boost from 4K if you want)-30psi gauge and its been pegged to a datalogged 37psi (sensor max). - completely silly levels I would not advise, but when it goes, by christ it goes... I have 10-12psi available from 3500rpm and off gauge from 4Krpm

in fwd its... as you would expect.... traction limited, but no worse (possibly better than PE) as its torque delivery is less aggressive but more sustained. (flat)

PE was working hard to get the high 300 numbers on the JS mani...setup of before.

I changed my mani an turbo so its a combination of parts which give the results, so spool on mine is maybe better due to equal length, but flow ability is massive.

Intresting stuff. Must be a fun car to drive.

 

[traumapat]

we are forgetting the smaller ihi vf24. coming from a mapped k03s there is slightly more lag but less than i expected. powers maxed out at 320bhp iirc

the real difference imo is that the power stays strong right through to 7k rpm. it just keeps going. very different car.

 

[ibizacupra]

Intresting stuff. Must be a fun car to drive.

fun as in... scarey to be honest.,
I think I can drive a bit... but this has to be very much respected. On the public road, with cambers, bumps, potholes etc, its lethal! a std ibiza would have me I would imagine. smoother surface all is better but a handfull. traction is better than hoped tho considering the headline numbers, which is down to the torque level being progressive and not high.

revised front end suspension setup completely just, with test day saturday to see if its better.... which it should be.

its daft & very scarey. you would annihalate anything in it up your way.

 

[ibizacupra]

my fear of IHI's given my experience of them is they are fragile when pushed too hard. good package and I rate them higher than a GT28 RS, but they have limits, and eager as they are to produce almost any boost you ask of them mid range, they can eat themselves in the process. ~(bearings or heat damage to exhaust housing)

 

[leonturboboy]

my fear of IHI's given my experience of them is they are fragile when pushed too hard. good package and I rate them higher than a GT28 RS, but they have limits, and eager as they are to produce almost any boost you ask of them mid range, they can eat themselves in the process. ~(bearings or heat damage to exhaust housing)

wow, sounds out of this world. cant wait for my ihi now!

@badger, you building a road car for yourself with same spec?

 

[ibizacupra]

wow, sounds out of this world. cant wait for my ihi now!

@badger, you building a road car for yourself with same spec?

no this is a customer car.

 

[ibizacupra]

some interesting figures... been setting up boost controller so been looking a bit closer.

15psi is showing just about @ 3400rpm, and by 4000rpm, off gauge (30psi) if allowed. spool is looking better than the PE1820 I had on before.(very close on spool considering the huge size difference between them. Mitsi hybrid has massive compressor and enormous turbine compared to the PE/IHI unit)