robbo_64

Had a Dawes on my car and set it up for 16psi, (just under fuel cut) and car felt much, much better in the 2750-4500 rpm range but then the boost deteriorates (rapidly) to about 10psi by 6000 rpm whereas under control of the ECU it only tails away very slightly. Not sure if this is normal or a feature of the bleed hole in the Dawes.
Is the solution to holding boost higher up in the rev range to get a proper Electronic Boost Controller or is there something else that can be done to improve this?
Can someone help?
Ta,
Neil.


[Edited by robbo_64 - 1/27/2003 3:02:27 PM]

john banks

What turbo and actuator? What size bleed hole?

robbo_64

John,
it is a standard MY98 UK Turbo, (not sure what turbo)with 1.5mm bleed hole, what do you think? Car is running K&N panel filter, Scooby sport DP, decat centre and Scoobysport BB
Neil.

[Edited by robbo_64 - 1/27/2003 3:13:10 PM]

john banks

The TD04L turbo you have is small, the exhaust housing doesn't flow well so at high RPM the wastegate is blown open. Mine was quite weak and losing boost from 4500 RPM.

You can tighten the actuator by removing the heatshield and the circlip and undoing the 10mm nut on the arm, and then tightening say 2 turns at a time. You will then bring up top end boost relative to midrange. You will have to slacken off the Dawes though to stop midrange overboost.

Stop when you see 14 PSI at 6000 RPM in 4th gear.

Usual disclaimers apply, get it wrong and your turbo or engine will blow up. As always check/consider detonation, fueling, injector delivery, fuel pressure, intercooler, plug heat range and gap, boost pipework and engine breathing, as well as potential boost leaks. Boost pressure is not a substitute for airflow.

[Edited by john banks - 1/27/2003 3:30:27 PM]

robbo_64

Thanks, John,
is it viable to get the exhaust housing ported etc. or is it a lot of expense for not a lot of gain. Is the real answer a hybrid turbo or such like, or should I buy a MY99/00 car and get it remapped etc. !!!
Neil.

john banks

I had a TD04L hybrid with a bigger compressor and clipped exhaust wheel and it was a moderate improvement in power, but only really up to 300 BHP. Think about a front entry TD05 for up to 350 BHP.

robbo_64

John, which way is it to tighten it or is it obvious when the heatshield is off/lock-nut undone?
Thanks,
Neil.

john banks

Shorten the rod to hold the wastegate shut longer.

Claudius

I really like the AVC-R because you can fine tune the boost so well, over the whole rev range, according to gears, start duty, etc. and virtually eliminate response time. A bit pricey, though.

I am getting a MY 97 (tomorrow, hopefully) and have already ordered a turbo kit and ECU for it. How about that? £4000 and you have a car that accelerates better than any later model scooby.

markwild

Stupid Question Warning :-

John, what do you think the limit (BHP ) for the 98MY standard turbo is ?

I've taken your comment to be 300BHP for a modified one, therefore standard is lower.

Having fitted ITG Panel Filter, de-cat centre and Backbox and about to fit DP, am I at the limit ?
I don't fancy messing with the wastegate, but I could get someone with experience to do it...

Or am I just missing the point and should go back to something I know about, like ...err...err...

Cheers,
Mark

carlos_hiraoka

Claudius, hope the turbo kit comes with bigger injectors as a stock MY 97 comes with 380cc grey injectors

john banks

Mark, depends on whose rolling road, but I would say 270 BHP tops.

markwild

John,

so what would you say to this ?

(Particularly, the saving up for something else part ? - or is a DP a good next step ?)

TIA,
Mark