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1/4 mile times?????


BillyWhizzz2002

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QUOTE
I'm running a slightly larger turbo than a GT28RS, I've had the compressor and exhaust housing's modified/ ported and also run an external wastegate.

I reckon the turbo I am using is good for 420 at 2 bar.

So like me you've cleaned up the housings, I guess as you say slightly larger than an RS you mean a 2871 or are you using one of he non Garrett models?  If it's the 2871 then 400-420 is right at the top end of it's scope pushing you into the low efficiency areas of the map so I'd be extremely interested to see how you get on.

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A friend of mine made 525bhp at 2bar boost last week on Harvey Gibbs Dyno Cell on a Zetec Turbo running a Turbonetics T66

A T66 is a really huge turbo compared to what you and I are running and 525bhp puts it smack bang in the high efficiency island.  2bar on a smaller turbo will not get you anywhere close but I guess you knew that already.

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The physics behind why you are not getting much more power out of your engine at higher boosts is that the AR ratio is probably small or your trim wheel is a small diameter and cannot release the exhaust gas fast enough, possibly your intercooler cannot cool the air volume above 14.7psi?

I've a huge great chargecooler so cooling isn't the issue, in fact air temps throughout our power runs are more or less constant as the heat just gets soaked up by the coolant and there's enough coolant in the system that we're never recirculating warm water.  What is happening is that it's pushing the turbo into low efficiency areas which increases the losses and backpressure so although more air gets in at the same temperature the parasitic losses also increase so on balance you don't gain anything.  300-320bhp is as much as you can get out of the 28RS, if you can keep the turbo in a high efficiency area then upping the boost can help overcome a poorly flowing engine but only if temps and efficiency are equivalent between the two boost levels.

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Probably the real reason why you noticed  that 1 bar gave the best results is that after this amount of boost you start to get wheelspin on the rollers?

Kit cars are so light that they cannot grip properly on rollers above 300bhp IMO unless you are using 12" slicks.

Get real, you notice wheelspin, it's stinky, smokey and most of all it's blindingly obvious on the dyno plot.  It's also laughably easy to strap a westie down so that wheelspin isn't an issue.  Straps back from the RAC bar clamp it so tightly it really isn't shifting no matter what you do, if you're really paranoid you stick some sandbags on the bootlid and put someone in the passanger seat but it's really not needed.

QUOTE
IMHO the more boost the better for making power if the engine and turbo are spec'd correctly to cope.

More air + more fuel = more power  FACT

That's a huge oversimplification.  It's only true if compressor and turbine efficiencies are equivalent, if charge temps are constant, that you don't have to retard the timing and half a dozen other caveats.  There are cases in which adding fuel and air leaves you with no more or worse less power.  

QUOTE
Andy made over 610 bhp at the wheels at only 2 bar boost with no gas on AET's brand new Dynopack hub dyno which is accurate to 1/4 of a horsepower.

Pet engineer bugbear here, you're confusing accuracy with resolution and ignoring repeatability.

QUOTE
Also be very carefull when porting heads as it is a black art.

I have seen heads that have been ported by so called tuning companies that make big claims only to find that they flow less air than a standard head. This was done on a friends superflow head flow bench.

I'd totally agree that some of the tuning companies are deceitful monkies.  Porting is far from a black art though, it's complicated for sure but anybody that's reasonably smart can understand the principles well enough without resorting to compute farm to model the airflow or vast stacks of heads to practice on.

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(cng1 @ Jul. 05 2006,09:04)

QUOTE

Appologies if my previous remarks seemed like critisism, it wasn't intended.

I'm not here to debate with you to see who thinks they no more about turbo's and the like quoting formula etc etc.

Frankly I don't really care

I'm here only to talk about 1/4 mile times. (were off topic slightly)

Whats the best 1/4 mile time you have acheived?

The proof of the pudding and all that.  :p

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Proof is in the puding indeed but you can't really compare apples with pears, in particular a screened car with a screenless one.

FWIW My car did 12.5 back when it had 75bhp less than it does now http://www.seight.com/perf/jfelstead.html with a full screen, the comfy leather armchairs and all the other "touring" paraphenalia.  On my very first run on my very first trip to a strip with all the tools still in the boot and a full tank of fuel I had the same terminal velocity as Johns 12.5 despite missing the first gearchange and then the boost hose coming adrift as I changed into 3rd leaving me effectively treading water for the last 1/8 mile.  Suffice to say that 12.5 is looking very weak to me if I can be bothered to put up with the queuing and do another trip to pod.

Get your slips off to Ian crocker and you too can get in the listings: http://www.seight.com/perf.html

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BTW I got pulled off tangentally and completely forgot the reason I started posting in the first place Austen.  You say that you are currently running 11s and think that upping the boost is going to get you into the low 10s, what I wanted to make sure that you were aware of in quite how large an improvement that is.

If you'd said that you wanted to get below 11s then that would be a reasonable target, going quicker than that will be very hard work.  It might be an idea to try using one of the performance simulators to help set your expectations as to what may be achievable..

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FWIW My car did 12.5 back when it had 75bhp less than it does now http://www.seight.com/perf/jfelstead.html with a full screen, the comfy leather armchairs and all the other "touring" paraphenalia.  On my very first run on my very first trip to a strip with all the tools still in the boot and a full tank of fuel I had the same terminal velocity as Johns 12.5 despite missing the first gearchange and then the boost hose coming adrift as I changed into 3rd leaving me effectively treading water for the last 1/8 mile.  Suffice to say that 12.5 is looking very weak to me if I can be bothered to put up with the queuing and do another trip to

Was there a head wind too?

:p

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Austin

May i make a suggestion ???

If your gonna continue with this kind of thing fit an RAC type roll bar........

You know it makes sense... :t-up:  :t-up:  :t-up:  :t-up:  :t-up:

P.S. Still gutted that i never got the chance to have a drive when we were over in France.............. :down:

Have to say Austins car is a credit to his attention to detail, everything has been thought about and it looks a peach............ :cool:  :love:  :cool:  :t-up:

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Hi Andy

You have a memory like a sieve

I've already got one fitted, over 6 months ago now.

The sig I have is a year old.

Thanks for your coments

I'll let you have a drive next time I see you,

PS its alot quicker since I took you out in it in France.

Cheers

Austen

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QUOTE
You have a memory like a sieve

Not quite, a sieve serves a useful purpose...... :D  :p

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I did an 11.98 in a with a standard busa engine at Thorney Island.

Would be interested in giving it another go now its turboed !!

Bazzer

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You have a memory like a sieve

Not quite, a sieve serves a useful purpose...... :D  :p

Andy

Will you be coming to Elvington on the 30th July for Ten of the Best to give me a hand? Get all the Manachester / Yorkshire boys rounded up.

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You have a memory like a sieve

Not quite, a sieve serves a useful purpose...... :D  :p

Andy

Will you be coming to Elvington on the 30th July for Ten of the Best to give me a hand? Get all the Manachester / Yorkshire boys rounded up.

I should be there DOG willing....... :D  :suspect:  :p  :D  :t-up:

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BTW I got pulled off tangentally

I think you should keep that to yourself, or we'll all want a go :blush:

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Don't know if anyone has mentioned it yet, but what about a  seven day at Santa Pod, get as many sevens there as possible, a few traders and the like there and all have a blast. It's not just the straight line there now either, they have a drifting area too, maybe a donught of the day competition.  :D Probably won't get many cateringvans there though, don't think it would be there cup of tea, but who knows. I think the seven style car is popular enough to get enough people turn up.

Any thoughts ?  ???

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I'm up for that, the cambs area did a run wot u brung day there last year.  Was pretty cool, neil got beaten by a scooter iirc.
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