Lude Generation

I have a small turbo from a passett 1.8.

Is there much i would need to change if i run very very low boost?

injectors, management,

AndyPandy1 wrote:I have a small turbo from a passett 1.8.

Is there much i would need to change if i run very very low boost?

throw it away, no use for a small turbo on a H22 engine, they suck in loads of air and require a large or hybrid turbo just to get enough air in.

it sounds like you need to do some reading before you go any further as the H22 moves at least 32lb/min airflow which means a big turbo is needed, problem is getting a small amount of boost from a big turbo makes the turbo quite in-efficient.

search for a book called "Forced Induction & Performance Tuning" by Graham Alexander Bell.

the only turbo book you will ever need.

^ that thought was running through my head, the turbo from a Passat is likely a K03 and they only produce 150PS stock on that engine - the N/A 1.8 20v produces 125PS... The 1.8 turbo lumps can be remapped to a max of about 190PS before the turbo has to be upgraded, so I wouldn't have thought a K03 turbo would be much use on a H22A

if you're looking to run a low boost setup (about 6-7psi 275bhp) you'll still need a big turbo to move the air.

problem you have then is it's a big turbo trying to run at low boost and becomes very in-efficient.

if you check the compressor maps for turbos (Honeywell have all the compressor maps for their turbos etc..) then you see that:

with 32ft/min air required for the engine, and a pressure ratio of 1.5 (around the 6-7psi 275bhp mark) you'll struggle to find a turbo the right size that keeps you within the "efficiency island" on the compressor map.

if you look back at past turbo conversion makers for H22's (greddy, apexi?) you can find what turbo they used, generally they will be big old girls.

the best thing to do is a run a hybrid turbo, ideally looking for something on the T3-T4 size . Kinugawa do some good japanese turbos and you can get a hybrid unit delivered to the UK for about £500-600.

check out the compressor maps for the Holset HX40 & TD05H 60-1, you'll find both of them have some suitability for the H22A but would still really need to be hybrid to get the best out of them.

if you choose to go high boost, then all your turbo options are much easier since a lot more off the bigger turbos would be suitable if you're looking for a pressure ratio of say, 2.0 (400bhp ish).

Just supercharge it. 295bhp @ 6psi

Id stick a gt35 or a hx35 on it and enjoy it

EG_H22 wrote:Id stick a gt35 or a hx35 on it and enjoy it

HX35 doesn't seem to flow enough air to get the most out the turbo, the more efficient it is, the more usable power you'll have to enjoy.

the HX40-B8554M seems to be almost perfect for the application; the calculations put the H22 right at the start of the middle efficiency-island on the compressor map with loads of scope to add more power later and turn the turbo up and still be well within the turbo's optimal operating range.

up to you what you get really but just make sure you realise how much air the H22 requires just to operate N/A, this has a big bearing on the turbo required.

or supercharge it innit.

Im interested in this also

Can anyone tell me what this kit would be like??

http://www.turbokits.com/Honda/Prelude/Turbo_Kits/

MaccaIRL wrote:Im interested in this also

Can anyone tell me what this kit would be like??

http://www.turbokits.com/Honda/Prelude/Turbo_Kits/

looks like a cheap ebay-special turbo kit. i wouldn't touch it with a bargepole tbh.

the turbo is the most important part so don't substitute it for a piece of shiite.

buying the parts individually is a better option, all those ebay kits are rubbish from china.