To IHI or to K04...

[Koomorph]

For the last couple of months I've been collecting all the bits needed for an IHI conversion on my Cupra (K03s), to the point where I'm nearly there and only need the downpipe from Jabba. I've got the turbo, injectors, water and oil feeds/returns, larger MAF, exhaust, FMIC etc…. So the project should be ready to be bundled and mapped in the next month or so. However, the closer I get to D-day, the more I've been thinking whether I'm doing the right thing…. in terms of turbo choice…..
… and I've begun to considering whether rather than an IHI, I should downsize my choice and go for a K04 instead… !

The 2 main resons behind this thinking are - concerns about reliability and potential lag…

I know that with a K04 setup I could be pushing 280+ and hardly have any detrimental affect on when it comes on boost compared to my K03s - which I really like. Plus K04 fitment would be easier (and cheaper) and turbo reliability (plus internals going "crack") would not be an issue. One thing I fear most is the IHI failing and having to spend loads on a new one (as it cannot be rebuilt - although I do plan to only run 1.4bar max). I know that with the K04, I would have a much faster car than I have now, yet have fewer concerns about reliability compared to if I went with the IHI option.

Or should I stick with the IHI plan, and hit 330, and live with the lag and constant fear that something may fail…. But also to throw in the mix is that re-sale values of my car in a year or so would be greater with an IHI fitted that with a K04….

Let me know your thoughts chaps as I'm currently in a state of indecision…

Cheers
Raf

 

[Feel]

Stick to the plan. At 330 I don't think lag or reliability will be much of an issue will it? (I've no direct experience though).

K04 won't give you that much more than the K03S, well not for the amount of grief, anyway. A good K03s car is knocking on the door of a reasonable K04 car. K04 feels faster, but isn't that much faster from A-B in reality.

The smaller IHI cars I've been lucky enough to have a passenger ride in, didn't feel hugely laggy compared to a K04 car (maybe compared to a K03), but the difference in the way it spools etc etc is remarkable.

It seems that with an IHI setup, you'll have more choice of further upgrades in the future than with K04, and as longer your tuner doesn't push it too much the manifold etc should last...

 

[Ruddmeister]

Stick with the IHI plan, you will be dissapointed with a KO4 conversion IMO

 

[Wilko]

If you want K04, don't waste your time converting what you have as it is cheaper to buy a cupra R.
Don't think a chipped cupra R won't break internals, because it's happened.
Modified cars are not for the squeamish.

 

[Koomorph]

Thanks for the input chaps - really appreciate it - and glad that people are saying that I should stick to the plan as I think I was begginning to wonder...

John, noted about the Cupra R, hadn't considered that - and I take your point about internals on chipped cars - I'm far from squeemish, just like to have my cake and eat it...

Phil - how exactly does it spool differently to a K04? - I've not been in a K04 car - have been in an Jabba'd IHI'd 1.8T Lotus Elise...John's 18G'd Golf)

Raf

 

[h17och]

you will always want more (as ive found out) so go big 1st then next time you upgrade it will be a weapon!!

HoocH

 

[Wilko]

Raf
On a 6 speed, the lower gears are so short, that lag shouldn't be an issue with IHI. fully spooled by 3500 vs 3000 on a k04, but it's over a bar by 2800 with the 18 housing.
With a 5 speed and the long gearing lag can be more of an issue, which is one of the reasons for me going 6 speed.

Don't worry. Just bolt it on, run 1.2-1.3 bar and grin, a lot. Internals will be fine.

 

[Feel]

Thanks for the input chaps - really appreciate it - and glad that people are saying that I should stick to the plan as I think I was begginning to wonder...

John, noted about the Cupra R, hadn't considered that - and I take your point about internals on chipped cars - I'm far from squeemish, just like to have my cake and eat it...

Phil - how exactly does it spool differently to a K04? - I've not been in a K04 car - have been in an Jabba'd IHI'd 1.8T Lotus Elise...John's 18G'd Golf)

Raf

If you've been in John's you'll know what I mean when I say that when it spools it goes and goes and then keeps going.

Well, it USED to

Whereas the K04 spools a tad earlier but runs out of puff later on. Don't get me wrong, I like the K04, it spools early and the shove it gives is great/addictive, just that if you've got the IHI kit it's going to be more "special" for your trouble.

 

[caney]

i found going from a ko4 to ihi improved driveabilty! didn't notice any lag at all tbh and although the ihi is a fairly small turbo it's far superior to a weedy ko4. if you're worried about reliability then keep the boost low like wilko says,trust me that guy knows what he's talking abouti recently sold my ihivf34/20g with 10,000 miles done and peaking at 1.8bar,had it fully checked over and it was given a clean bill of health

 

[Koomorph]

Righto, thanks for all this chaps - very helpful. I've decided to stick to the original plan and go with the IHI.

Raf

 

[Triple D]

i found going from a ko4 to ihi improved driveabilty! didn't notice any lag at all tbh and although the ihi is a fairly small turbo it's far superior to a weedy ko4. if you're worried about reliability then keep the boost low like wilko says,trust me that guy knows what he's talking abouti recently sold my ihivf34/20g with 10,000 miles done and peaking at 1.8bar,had it fully checked over and it was given a clean bill of health

Hows the new turbo steve? all mapped and ready to go??? will have to pop up yours one weekend again for a catch up chat and ill take you out in my 100bhp arosa aswell if you take me for a spin in the TT again

 

[Feel]

weedy ko4

Oi, some of us are quite comfortable with the size of our compressors, thankyou

Remember, it's not the size that counts, it's how you use it

 

[Triple D]

Oi, some of us are quite comfortable with the size of our compressors, thankyou

Remember, it's not the size that counts, it's how you use it

 

[Ianb]

Certainly from what I've seen is that the IHI car's seem to spool very well.

I know my APR Stage 3 kit spools much earlier than expected. It's pulling well from just over 2k and by 3K it's flying all the way to 7k.
I have a 5 speed box on my car which isn't a detriment to it's driveability over the KO3s that was in situ before.
I agree that the 6 speed has shorter ratio's which can be of benefit for in gear acceleration though.

Ian

 

[myk3]

it is much better to have a long ratio box like the 5 speed over the 6 speed with a bigger turbo'd motor IMO.

i like to stay in boost longer in each gear

 

[caney]

Oi, some of us are quite comfortable with the size of our compressors, thankyou

Remember, it's not the size that counts, it's how you use it

you keep telling yourself that mate

 

[ibizacupra]

Raf
On a 6 speed, the lower gears are so short, that lag shouldn't be an issue with IHI. fully spooled by 3500 vs 3000 on a k04, but it's over a bar by 2800 with the 18 housing.
With a 5 speed and the long gearing lag can be more of an issue, which is one of the reasons for me going 6 speed.

Don't worry. Just bolt it on, run 1.2-1.3 bar and grin, a lot. Internals will be fine.

Having had 6spd I am more than happy to be back on 5spd and long gears.
lag is only an issue if off boost and at wrong rpm...
significantly faster when not having to change gears so often and the time lost in doing so.
If your after being sub 3k rpm and wanting it to go fast buy a diesel, your in the wrong car

 

[ibizacupra]

I agree that the 6 speed has shorter ratio's which can be of benefit for in gear acceleration though.

Ian

5spd and BT with high power is much better.
6spd is more gear changes and lower geared so spin up is more of an issue.

I'm glad to be back on 5spd box again.
(just need it strong enough tho )

 

[Wilko]

5spd and BT with high power is much better.
6spd is more gear changes and lower geared so spin up is more of an issue.

I'm glad to be back on 5spd box again.
(just need it strong enough tho )

On a track, where staying in boost is easy, I'd agree, but speed through roundabouts is often controlled by the guy in front of you, and exiting roundabouts in second gear can be lag, lag, lag, lag, and then off you go. Second is good for nearly 80mph in a 5 speed, and you're over 30-35mph before you're in boost, so the diesel you were hassling is 3 car lengths ahead of you before you hit boost.

But the diference is only 1-2-3 in 6 speed equals 1-2 in a 5 speed, and 4-5-6 in a 6 speed equals 3-4-5 in a 5 speed. For track work you'd just be using 3-4-5-6, instead of 2-3-4-5, so no more gear changing should be needed.

You can hardly drop it into first for roundabouts, and dual carriageways with roundabouts every 1/2 mile are common around here, and get used for some friendly performance testing against others.

But 5 speed boxes and drive shafts are not strong enough in my heavier car, and a 6 speed using diesel drive shafts is as strong as oem gets, so that's the way i've gone.

 

[Ianb]

Wilko

Have u had a drive shaft failure??

Not heard of that before on the 1.8t yet.

I find my 5 speed box ideal....it's all about planning IMHO....even more so on the road....track work last year on KO3s will be different on this new set up...there was loads of punch in Quarry at Combe exiting in 3rd....just quickly ran out of puff.

Braking will need a re think me thinks