ZXR750 turbo conversion

Nice job so far, Fro......looking forwards to seeing it run......

Looks quality that Mr Fro, could have made me a new set for mine

Looking good Fro

What'll be the effect of installing the turbo? I assume it's more than simply “the same as before but more so”?

question>

Looks quality that Mr Fro, could have made me a new set for mine

Don't look too closely!

I forgot it was a bank holiday so I'm hoping to get the plenum machined - maybe welded depending how I get on with it. I should have got hold of the oil lines and stuff but.. well... brain fart.

Lats - all you're doing is increasing the intake pressure which will give you more power out of the engine. Should make it quite nippy.

Sounds perfectly straight-forward when put like that! Have you taken some “before” measurements for comparative purposes?

Edit: Yes, yes you have. Of course. 109bhp.

How a turbo works if you're interested

Looking good Mr Fro!

Hard to see from the last photo, but is the turbo offset to the left or positioned centrally?

Just wondering about uneven header lengths to the turbo sucking power..

It's not a great pic - the turbo mouth is central to the headers. I'll grab another snap when I have it off for grinding.

Fro....Is the turbo a variable vane turbo? if so how are you going to vary the vanes?

It's not a great pic - the turbo mouth is central to the headers. I'll grab another snap when I have it off for grinding.

That's should be ok.. looked like it was over to one side which would have been weird with three different lengths headers to the turbo..

Yup, it's a VNT.

I stripped out the original vacuum actuator, fiddled a bit and turned it in to a pressure actuator but it's going to be a struggle fitting it in (ugly too) - might be able to get it in with a linkage in the control arm.

I've got a spare output from the ECU that I can program to switch on and off at a preset value which I can use to drive a servo instead. I'm concerned that it might give me a bit of a choppy delivery though.

If I'd have thought about it when I bought the ECU I would have got the 4 channel version rather than 2 channel which has a couple of variable outputs for EXUP and stuff.

Any bright ideas are welcomed!

some sort of servo control from the throttle linkage?

You mean keep the vanes open with open throttle?

I mean some sort of variable control running off the linkage so you get a steady boost rather than an on and off?

Needs to be linked to engine revs not throttle position.

Otherwise giving full throttle at low revs would cause too much back pressure on the exhaust.

Ideally you need a combination of revs and throttle position to control the actuator servo..

good point there Joe

This might give you some ideas..

http://www.tuning-diesels.co.uk/digiboosters/

Forgot to say that I've got a MAP sensor to slot in to the plenum which will drive the on-off from the ECU...

That box looks promising Joeman - fairly cheap too. Might get that unless I can find someone to buy my ECU so I can get the 4 channel.

Ideally need the actuator to vary the blade geometry with engine speed - not just on/off.

Also with no wastegate you'll need a way to regulate boost pressure otherwise the first time you go full throttle you will overboost and blow the motor.

That is a concern.

The on-off is boost referenced so it *should* maintain pressure. It's not ideal but it'll do until I stump up more cash for a decent solution.

I could fiddle the dump valve so it'll just vent anything over x psi.

On another note, I had a right result today at school - I went and use a chat with the workshop boss. I told him what I'm up to and he's given me free run of the whole show. 20 odd lathes and milling machines, top of the line welding gear and all the consumables I can get through.

I found a place near me that makes up hydraulic lines so nipped in this morning. £50 later I've got some rather agricultural looking oil lines.

I found a recessed bolt at the end of the oil rail and next to the oil pressure gauge which will do nicely for the feed. I'm still scratching my head where to put the return though.

I'm so close to firing it up to check the turbo actually works but I need a 3/8 to 1/4 adapter. I reckon I've got something I can adapt if I can figure out screw cutting on the lathe...

3/8 to 1/4 adaptor you say. Do you need a male/male adaptor?

Yep. I found a bit of brass and made one up. It'll do for now...

I've half sorted the oil drain - there's a drain line going from the pickup cover to the sump that I've been eyeing up for a while. I was going to drill and tap it but I didn't have the right sized tap so I started making one (plus I didn't want to shag the original in case it goes tits up).

Here's the original and some bits I made:

I cut and drilled the flange and turned down some tube which I chopped to give me the correct angle.

Here's the tack up:

You can't really see in the pic but it's an odd fitment as it's a dogleg type thing. I made it a bit longer so I can add a drain tube near the flange.

I just need to drill a hole for the additional drain, weld it up and slap it on. After that I'll get it fired up and see whether the turbo actually spins.

I could get you a proper fitting from work mate, depending on the thread, are they parallel? I could get you some seals too.