100 MPH
08 June 2009, 04:23 PM
#1
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100 MPH
I have a standard top mount on my 97 UK Turbo and I have been told if I stray much over 100 mph I risk engine failure due to temps getting too high etc. I have had a remap and i'm running 319 bhp.
Is a FMIC the only option to resolving this?
Do I need a FMIC to safely go above 100 mph?
Any advice welcome
Is a FMIC the only option to resolving this?
Do I need a FMIC to safely go above 100 mph?
Any advice welcome
08 June 2009, 04:48 PM
#2
Who on earth told you that crap?
Engine failure at 100 is not caused by inlet temps. If anything it will be oil starvation after prolonged high speed that will cause engine failure. This usually happens when people try and " see what it can do" ie what top speed can i get. But a steady cruise will not overheat your engine. If anything inlet temps would be reasonably cool @ 100mph certainly nothing out of the ordinary.
Engine failure at 100 is not caused by inlet temps. If anything it will be oil starvation after prolonged high speed that will cause engine failure. This usually happens when people try and " see what it can do" ie what top speed can i get. But a steady cruise will not overheat your engine. If anything inlet temps would be reasonably cool @ 100mph certainly nothing out of the ordinary.
08 June 2009, 05:12 PM
#3
I've heard similar - there's a thread on here somewhere from about a year ago discussing it - it wasn't engine failure, but something about damage to a couple of bits that could be caused by cruising at that speed because there's a defect with the design of the bonnet scoop on certain models meaning not enough air gets in at higher speeds.
I'll see if I can hunt it down...
I'll see if I can hunt it down...
08 June 2009, 05:13 PM
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I see what your saying. Why is there a risk of oil starvation at higher speeds though? Your at higher revs for longer?
I thought I had read somewhere that the front end wasnt very areodynamic, and that at over 100 mph their is very little air actually getting into the intercooler?
Any truth to that?
I thought I had read somewhere that the front end wasnt very areodynamic, and that at over 100 mph their is very little air actually getting into the intercooler?
Any truth to that?
08 June 2009, 05:18 PM
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One of them SNet things with little or no actual hard proof to back it up.
For sure you will get better airflow through a front mount than top mount at 100mph but then you will at most speeds. Subaru fitted much bigger scoops to the first of the blob eye STI (MY03+) but then got smaller again so perhaps they improved the airflow in other ways but make of that what you will.
For sure you will get better airflow through a front mount than top mount at 100mph but then you will at most speeds. Subaru fitted much bigger scoops to the first of the blob eye STI (MY03+) but then got smaller again so perhaps they improved the airflow in other ways but make of that what you will.
08 June 2009, 05:19 PM
#7
i also heard that the bonnet scoop was not very effective at high speeds, thus increasing intake temps.
jap imports are supposed to be restricted to 112mph and there is a question as to how well they are mapped over this speed. you have a uk car so this does not apply.
i am of the belief that if you do a sustained top speed run i.e 130+ then you are asking for trouble.
jap imports are supposed to be restricted to 112mph and there is a question as to how well they are mapped over this speed. you have a uk car so this does not apply.
i am of the belief that if you do a sustained top speed run i.e 130+ then you are asking for trouble.
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08 June 2009, 05:34 PM
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Well I have a bigger (or rather later one I should say) scoop on my 97 Uk Turbo.
So what I was thinking is right in a way then? But the danger is due to restricted air flow and hence high oil temp/starvation?
I had a big OEM V2 Induction Kit on my Type R to help it breathe better, is there nothing similar for the Impreza that would help? Or do I simply need a FMIC to go over 100 mph with any confidence?
So what I was thinking is right in a way then? But the danger is due to restricted air flow and hence high oil temp/starvation?
I had a big OEM V2 Induction Kit on my Type R to help it breathe better, is there nothing similar for the Impreza that would help? Or do I simply need a FMIC to go over 100 mph with any confidence?
08 June 2009, 05:42 PM
#10
Here we go:
From Damian Harty of Prodrive in 2003:
This one says the problem's more for classics:
https://www.scoobynet.com/general-te...-bull****.html
There's some discussion in the threads below that 100mph+ is fine with a stock car but not necessarily with a modded one, unless you've got a decent set of gauges to monitor it!
https://www.scoobynet.com/general-te...ed-runs-2.html
and this one from 2005...
https://www.scoobynet.com/general-te...er-100mph.html
From which the last post is most interesting:
It does sound like though the main problem is the aerodynamics on the classic not lending themselves to channelling as much air into the scoop at high speed.
From Damian Harty of Prodrive in 2003:
To a point, increasing the height increases the air the intercooler receives.
Two things influence the flow through the intercooler, one is where the air comes from and the other is where it goes to.
If you imagine that the exit air is somehow restricted then you can increase the inlet air (i.e. bonnet scoop) all you like but it won't get any more air out the exit - i.e. through the intercooler. This is a slightly simplified version of reality but close enough.
On the rally car you'll note we put the intercooler right down at the front and exit the air before it gets near the engine compartment, over the bonnet. Ironically enough it exits right into the now-blanked scoop.
This has a lot to do with keeping air out from under the car (important for cutting lift) and a little to do with intercooler efficiency. We sacrifice some radiator area compared to the road car because we don't need to sit in a traffic queue climbing the hill out of Death Valley, which is just about the worst situation a road car is engineered for - low speed, high load, high ambient temperature.
I'm sure the modified scoop on the new car is an incremental improvement although "optimum" suggests to me there's no possible further improvement, and I never really believe that...
Two things influence the flow through the intercooler, one is where the air comes from and the other is where it goes to.
If you imagine that the exit air is somehow restricted then you can increase the inlet air (i.e. bonnet scoop) all you like but it won't get any more air out the exit - i.e. through the intercooler. This is a slightly simplified version of reality but close enough.
On the rally car you'll note we put the intercooler right down at the front and exit the air before it gets near the engine compartment, over the bonnet. Ironically enough it exits right into the now-blanked scoop.
This has a lot to do with keeping air out from under the car (important for cutting lift) and a little to do with intercooler efficiency. We sacrifice some radiator area compared to the road car because we don't need to sit in a traffic queue climbing the hill out of Death Valley, which is just about the worst situation a road car is engineered for - low speed, high load, high ambient temperature.
I'm sure the modified scoop on the new car is an incremental improvement although "optimum" suggests to me there's no possible further improvement, and I never really believe that...
This one says the problem's more for classics:
https://www.scoobynet.com/general-te...-bull****.html
There's some discussion in the threads below that 100mph+ is fine with a stock car but not necessarily with a modded one, unless you've got a decent set of gauges to monitor it!
https://www.scoobynet.com/general-te...ed-runs-2.html
and this one from 2005...
https://www.scoobynet.com/general-te...er-100mph.html
From which the last post is most interesting:
About 3 years ago, I was lucky enough to attend a factory visit at Prodrive, whilst on the tour we visited the customer car baywhich had numerous classic shapes. Someone asked about the TMIC duct, I can remember the answer which cast doubt on its effectiveness on any speed over 90 mph, hence the newer cars have a taller duct.
Rent a windtunnel for £3k a day and have a play, I am planning to modify my original classic one taller, basically the windflow misses it at high speeds.
Rent a windtunnel for £3k a day and have a play, I am planning to modify my original classic one taller, basically the windflow misses it at high speeds.
Last edited by MrNoisy; 08 June 2009 at 05:45 PM.
09 June 2009, 11:19 AM
#13
09 June 2009, 01:27 PM
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I thought they said that at over 12 mph all the air would be sucked out of the vehicle and you'd suffocate.....
LOL
dunx
P.S. Mine achieved well over 150 mph (at Elvington), but was totally standard ! (Indicated 160 !)
LOL
dunx
P.S. Mine achieved well over 150 mph (at Elvington), but was totally standard ! (Indicated 160 !)
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