Currently I have a turbocharged Kawasaki ZX10R engine, Tial 38mm external wastegate with an 8psi spring and a manual boost controller to give me my upper boost setting, low boost 8psi and high boost 15psi.

During a recent mapping session we found that the boost controller wasn't controlling boost as it should, so I'm planning on fitting an electronic boost controller (particularly like the look of the Turbosmart E-Boost Street) and a smaller wastegate spring.

Doing the above would give me 3 boost settings...

1) 4psi from the wastegate spring
2) 8psi low boost using the controller
3) 15psi high boost using the controller

Can you go too small with the wastegate spring in comparison to the maximum boost you wish to run? is there an ideal or maximum ratio between the two? or does it make no difference?

 

Depends on the ability of the EBC and whether or not the physical w/g is correctly sized, or wrongly sized.
If they are at extremes, then smooth control is going to get harder

38mm w/g will be fairly large unless it's making a fair bit of power, but will also depend on turbo etc.

But 4psi to 15psi with a good EBC shouldnt pose any real problems.

 

The EBC is well regarded from what I have read online.

The 38mm wastegate is fitted to a tubular manifold and a GT3076, the engine is a 1000cc motorbike engine and revs to 13500RPM. Last year when setup it was controlling boost correctly, but this time the manual boost controller was playing up, hence looking to swap for an electronic boost controller and lighter wastegate spring.

 

Ive only ever used the E-Boost 2, and it does a superb job. Not sure how the street version stacks up.

It can certainly do no harm to try anyway with the softer spring, and an EBC is definitely better than a simple bleed valve device.

What ecu is in the car ? and can it not control the boost ?

 

as far as i know the low setting will be determined by the spring rate in the wastegate.
the upper will be a blend of spring and bleeding air off in the EBC.
i reckon you could get the 8psi spring to get you to 16 no problem with an EBC, stopping it spiking should be the only concern, but sorted with gain settings and closed loop etv.

 

The Street version should do exactly what I'm wanting, it's just wether the wastegate spring needs to be any stiffer than 4psi to get 15psi max boost.

The ECU on the car is a Power Commander III USB and it hasn't got the ability to control boost.

The EBC spec says it has two boost control settings, so rightly/wrongly I presumed if the controller was switched off you;d get wastegate spring pressure, and with it switched on you'd have a further two boost settings.

 

i wouldn't think a 4psi spring would be great getting to 15psi.
wht not try a 6psi one, then let the EBC go from there, this should be possible as my 8psi spring with my ebc on 90%duty will give 18psi.

 

You can mess about with the plumbing as well as the w/g controls themselves to manipulate the boost levels achievable. But it is a lot of hassle

It's still worth a try with the 4psi spring though. If it doesnt work, just go back to the 8psi spring.

I still dont think it's asking too much to make 15psi though

 

A 4psi or 6psi wastegate spring won't make much difference to me as i'll probably run a minimum of 8psi of boost anyway, but with the 4psi at least i'd have the option to drop the boost right down if required at some point.

Always good to hear peoples opinions on things though, so thanks for the input guys

and if you're interested this is what 8psi goes like with a passenger in the car

 

not bad performance, not too dissimilar to my xr2 with 17psi blowing though it

 

Well I bought the Turbosmart E-Boost Street from Motorsport Developments, free delivery too!



http://shop.motorsport-developments....ler-299-p.asp#

Now i need a new spring for the wastegate and something to replace my 52mm boost gauge.

 

It arrived this afternoon, 23 1/2 hours after ordering it from Motorsport Developments, you can't knock that for service! Thanks

 

love your car followed the build thread, good luck getting the boost setup with the new gear. what boost can it be run upto btw?

 

Thanks very much

A sensible boost limit is around 14-15psi, which is where I will draw the line, this should give around 300-330bhp at wheels, and be plenty quick enough, considering the car is very light.

The parts fitted to this engine are capable of running more boost/power, see the link below

http://www.bigccracing.com/shop/prod...0&source=thumb

but it starts to become less reliable the more you push. Both mappers I've used have told me the same thing, which is "making the power is not a problem, keeping the engine together is!", usually turbo bike engines are fitted to drag bikes and they don't tend to do many miles, so reliability is less of a concern to them as it is to me and my 5000 mile per year road car.

If i threw caution to the wind and ran a bit more boost, it'd make around 420-450bhp at wheels with 28psi, not bad going from 998cc's!