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GTRgeoff

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Posts posted by GTRgeoff

    Airbox Vs Pod Back To Back Testing

    in Forced Induction Performance

    Posted

    Andrew, I used one of the stock holes, but enlarged it a fair amount to allow the AFM to fit from underneath as well as have some tolerance for the hard split pipe it attaches to. I'll grab photos later.

    I understand your thinking on the feed to the airbox however I have found that AFMs are significantly effected by water hitting them so I want to have free air traveling to the filter, but don't want a ram effect due to the water problem, especially on the racetrack so this is a straight out compromise for reliable power. If water in large enough particles or mass contacts the AFM it maxes out and cuts power significantly. I discovered this with the HKS pod directly in front of the tyre in the rain. There was enough spray to reduce my speed in a 110 zone down to 60kmh and struggling. So this way the filter gets heaps of air but there should be limited water to deal with, even from a car in front.

    When we discuss Ram-Air effect in turbo cars we are really just nibbling the edges of the problem of air feed. It is more an issue of minimising negative boost or losses. In the GTR33 I'm only making 320rwkw @ 14psi and plan to lift to 18-20psi so the stock airbox in this case is sufficient for my street needs. Consider that a 3.0L engine such as in my track car at 7000rpm needs about 21000L of air per minute, but at 14 psi it now needs around twice that. So that is about 350L per second NA or about 700L per second forced induction. So we are looking at slightly smaller than a cubic metre of air every second which is almost half of the space under the bonnet. If we are lucky we might achieve about 6-10 inches of water of positive feed with a great ram effect. 10 inches of water is about .36psi so really bugger all. I'm just generalising the availability analysis right now. The turbo/s has/have a mighty job of dragging that air in so we do what we can to minimise the restrictions, but using rammed air from a stagnation point has both benefit and significant drawbacks. The fact is a turbo will pull the air in if restrictions are present, just not as well, but the ingestion problems in an AFM equipped car outweigh the benefits if there is a lot of foreign objects to be removed from the delivered charge or there is significant water suspension in the air. We can add direction changes and settling points, or if money and space are no problem then we can add cyclonic settling chambers or such, but most of us are on a hobby budget.

    Airbox Vs Pod Back To Back Testing

    in Forced Induction Performance

    Posted

    It's all good mate, I majored in aerodynamics at the one uni in the country with a Mach 3 wind tunnel or what we call a shock tunnel, amongst other useful stuff.

    While a simple approach would be to say that at least an extra 40rwkw would be available given Marks experience above, it depends on what the turbos are able to push, mass flow wise in Marcus' case. I forget your setup mate, but a fair guess would be a bit is available at that flow rate. Negative boost theories are all well and good but turbos have one simple role and that is to drag air in and compress it for delivery to the combustion chambers so it overcomes many restrictions, up to a point.

    Mark, having a think about this and were any of the turbo inlet hoses constricting? If the restriction to the inlet was enough there may be some cross sectional reduction in the inlets between afm and turbo which is a sure way for the restriction to increase so limiting flow. If hard pipes were used, for example, then they would resist the negative pressure and allow the flow to continue. So just a thought.

    Airbox Vs Pod Back To Back Testing

    in Forced Induction Performance

    Posted

    I strongly disagree that at those power figures that the bonnet open or closed would heavily influence pods at all unless heat was a serious issue, and ACT is still cold. Ther is plenty of available air around the headlight. Clearly the 32 box is a restriction but with modification, say a 90mm water pipe flange and a pipe through the inner guard 33 GTR style it would be more than adequate for most track applications.

    Some pics for Duncan.

    33GTR front and 32 rear

    IMG_0490.jpg

    33 GTR

    IMG_0489.jpg

    32GTR

    IMG_0488.jpg

    33GTR

    IMG_0487.jpg

    My custom box prototype on the track car using the std air filter and an internal bellmouth from the HKS pod on the inside top (the only good part of a HKS filter). It's a tight fit around the filter so the tape is only to hold it in position and the afm is mounted directly to the top. The from bar is intended to have slots to help feed it.

    IMG_0486.jpg

    IMG_0485.jpg

    IMG_0484.jpg

    The Switch Has A New Dyno

    in Queensland

    Posted

    Shootout uses different ramp rates so can effect the reading, but it doesn't say which mode, so I assume if Mick just keeps it right as it is the only comparison is his dyno.

    I note the boost level is up as well.

    Regardless, nice to know you are happy with it.

    So I Pulled My 26 Apart Today..

    in Forced Induction Performance

    Posted

    Here is the ACL RB26 page http://www.aclperformance.com.au/NissanRB2...rgedPistons.htm

    5 thou is the clearance so the build was wrong from the start. Pistons won't shrink. There is no way the bore has worn that much if you can still see crosshatching.

    That ring gap is horrendous.

    Quite possibly the combination of the large clearances combined to induce excessive detonation through high quantities of oil in the combustion chamber. Oil is a detonation contributor.

    I can offer a decent machinist/builder or two in Melbourne if you want, or just send it up to proengines for a good job. Word is he's tip top and has posted a detailed thread on here of one of his engine builds.

    Yo Yo

    in Queensland

    Posted

    Kemp is it?

    Welcome on board mate. Look forward to seeing you out and about. Try not to max the bottom end too much unless you are keen for a rebuild or have a good history of the cars' usage and most recent rebuild as they are getting on now the old 32's.

    Enjoy

    Geoff

    R33 Rb30 Conversion

    in RB30 conversions

    Posted

    Yes, I do. Well done Shane you are paying attention mate :dry:

    I am running a single Z32 AFM as my power goals aren't that extreme. If I do need to step up the grunt then I'll go twins and use an SAFCII or whatever the hell it is to combine the inputs, I'm no expert on that thing though so it could be one of the others. Then of course in the FC Datalogit you can log the output and tickle the ramp rates and the load spread to get better control.

    I do have a custom 1-2 pipe setup to allow a single so if you go twins the SAFCII is probably the easiest.

    The sensors that needed playing with were the O2 sensor, I extended the loom and plugged it in after the Y pipe join for twins but a single avoids this, and the water temp sensor which has a different voltage output, or at least the one in my head setup did so hang onto your water temp sensor just in case.

    R32 4dr Tail Light

    in Queensland

    Posted

    Since this is an easy case to defend in court yourself, and it would cost nothing except some time, ask to discuss the matter with a senior officer at the station this guy works at, ask for some intelligent intervention and state that you will take it to court if necessary.

    I'm pretty certain, if the evidence is presented to one of the older heads that they will see sense in not prosecuting.

    Judges hate to see matters that are just petty, pointless and wrong and will give the coppers a dressing down if they do present this case.

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