Best boost tap to use

[NB42]

I'm just wondering what boost taps people are using on their Diesel turbos?
I have an isuzu mu and would like to up the boost a bit, had it open boosting up to 15psi today by removing the wastegate actuator hose and it felt great but would like to do it properly. Cheers

[tweake]

any ball and spring will do the job. i've used nxs http://www.nxsmotorsports.com both the cheap one and the fancy one. both work fine.
only one i wouldn't recommend is turbosmart, simply because its not a ball and spring style its a bleed type with a ball/spring one way valve in it. also they are very $$$.

[johnny262]

Looking at boost taps too, whats the disadvantage of a bleed type tap?

Are these any better/more accurate? http://www.pro-wholesale.co.nz/boost-co ... fb-atomic/

[tweake]

bleed taps work ok but are usually better for petrols.
the problem ball/spring types can have is boost spikes which can be fatal for a petrol engine. but diesels generally don't rev up that quick and a boost spike won't blow up a diesel engine so its not really an issue on a diesel.
the advantage is that ball/spring is a bit quicker in building boost than a bleed.

there is combo units around which is basically a ball/spring for coarse adjustment and fine tuned with a bleed valve.

you don't really need high accuracy on a diesel.

[mudzuki]

Those GFB Atomic taps are regarded as one of the best, ran one on my old car and my friends performance shop wont run anything buy in their builds

[slidenyo]

biggest thing to remember is keeping your air fuel ratio at optimum or as near as possible,
boost by itself is largely irrelevant if the fuel supply doesn't measure up.
talk to your local mechanic about timing the pump, installing a gauge and adding fuel to suit,
look at the nitty gritty like tappet clearance and injector break pressures

[tweake]

biggest thing to remember is keeping your air fuel ratio at optimum or as near as possible,

where talking diesels here. theres no strict airfuel ratio to keep within. as long as you don't go to rich, a diesel doesn't care if you go lean.
as i said before accuracy in boost is not an issue in diesels, if it boost spikes it will go lean which does no damage. petrol engine on the other hand is a different ball game.

[slidenyo]

that statement is fundamentally incorrect^,
afr is just as important in diesel as in petrol,
leaning out or enrichening the diesel afr is no different to tuning a petrol other than the heat causing elements being opposite.
having that 15:1 afr allows the engine to run,
the nature of any hydrocarbon in combustion is that it will require a specific afr to do just that combust,
adding more fuel and boost will increase the rate of combustion, the amount produced and energy output,
but in doing this the afr will still remain very close to the 15:1 for the engine to run.

[tweake]

that statement is fundamentally incorrect^,
afr is just as important in diesel as in petrol,
leaning out or enrichening the diesel afr is no different to tuning a petrol other than the heat causing elements being opposite.
having that 15:1 afr allows the engine to run,
the nature of any hydrocarbon in combustion is that it will require a specific afr to do just that combust,
adding more fuel and boost will increase the rate of combustion, the amount produced and energy output,
but in doing this the afr will still remain very close to the 15:1 for the engine to run.

stick to your petrol tuning.

15:1 afr on a diesel will kill it. 18:1 is about max, around 22:1 safe, about 28:1 (or leaner) at idle. so much for "it needs 15:1 for the engine to run" lol

[slidenyo]

And there we have it you have just proved you know the relevance of afr in a diesel,
sorry to tease it out of you by posting a random number,
afr in diesel will indeed have a rich and lean mixture range outside of which it just won't run.
it would seem you have just debunked your own theory that it isn't relevant,
don't get me wrong I accepted a long time ago that it pays to consider I could be wrong before bowling ahead with loose statements.
especially in regards to advising some young buck to just disregard chemical and physical laws

[zed]

I'm just wondering what boost taps people are using on their Diesel turbos?
I have an isuzu mu and would like to up the boost a bit, had it open boosting up to 15psi today by removing the wastegate actuator hose and it felt great but would like to do it properly. Cheers

+1 for ball and spring type. Work fine on a diesel, as it is less important to control the boost ultra precisely like on a petrol. Some diesels have an ecu cut off at a certain boost level (14.2psi on the 1kz yotamota for example) but it's not hard to get around that. I suspect the isuzu 4jg2 doesnt though. Mattman on here may be able to offer more specific info though.

[tweake]

And there we have it you have just proved you know the relevance of afr in a diesel,
sorry to tease it out of you by posting a random number,
afr in diesel will indeed have a rich and lean mixture range outside of which it just won't run.
it would seem you have just debunked your own theory that it isn't relevant,
don't get me wrong I accepted a long time ago that it pays to consider I could be wrong before bowling ahead with loose statements.
especially in regards to advising some young buck to just disregard chemical and physical laws

thats way over thinking it.

the point was that running leaner due to boost spike won't kill a diesel. its extremely difficult to make them run too lean. even a factory diesel probably would do 50:1 at certain points.
theres no real need for a highly accurate boost controller unless your desperately trying to stay under the cut off point as zed has kindly pointed out.