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General FI questions - Rod strength and supercharger whine

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Hey all, two quick questions that I couldn’t find a clear answer on. Hoping you guys could help me get to answers please?

1. When using FI on the FA20 what is considered to be the real tipping point where you really start to risk bending a rod? Cosworth appear to say 280bhp at the flywheel is as high as they recommend you should go on a stock engine. But does anyone have any experience or has heard of rods bending below this level of power?

2. Which FA20 supercharger has the best whine? I know there is a lot more to supercharging your 86 than just how it sounds, but whine on a supercharger is a glorious thing. I’ve seen the MRT video for their Sprintex charger which is the best i’ve heard so far. Is this generally considered to be the one with the best whine?

Cheers!

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Cheers guys. So what you say confirms what I suspected SC whine wise from all the time i’d spent googling.

So I just need to decide whether I wanna go Cossie Charger or if its worth paying the extra for the Sprintex whine.

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I think I saw somewhere that a one let go at less than ~280 bhp, and I forget whether it was a turbo or not, but at least there's a sticker for that:

https://mightycarmods.com/collections/stickers/products/rodney-the-piston-sticker

Boost shortens the life of the engine unless it's designed for it or otherwise overengineered, so you shouldn't expect miracles, but supercharging at low boost is probably the least risky version of FI.

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Cheers guys. So what you say confirms what I suspected SC whine wise from all the time i’d spent googling.
So I just need to decide whether I wanna go Cossie Charger or if its worth paying the extra for the Sprintex whine.
Wouldn't go for a sprintex. Abbey have stop using em over issues with heat management

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Sprintex is outdated and was the first SC setup for this car. Has great mid-range but not so hot at the top end. It does whine pretty well though. The water/air intercooler is fairly limited in it's capacity though.  Cosworth don't do the kit anymore, but Harrop is pretty similar. Doesn't really whine though. HKS is my favourite from a driving perspective but some issues over reliablity potentially and expensive parts may put you off.  

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Sprintex is outdated and was the first SC setup for this car. Has great mid-range but not so hot at the top end. It does whine pretty well though. The water/air intercooler is fairly limited in it's capacity though.  Cosworth don't do the kit anymore, but Harrop is pretty similar. Doesn't really whine though. HKS is my favourite from a driving perspective but some issues over reliablity potentially and expensive parts may put you off.  
Still acouple cosworths floating around from other vendors lol. But if they're all gone by then it's harrop for me

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15 hours ago, nerdstrike said:

I think I saw somewhere that a one let go at less than ~280 bhp, and I forget whether it was a turbo or not, but at least there's a sticker for that:

https://mightycarmods.com/collections/stickers/products/rodney-the-piston-sticker

Boost shortens the life of the engine unless it's designed for it or otherwise overengineered, so you shouldn't expect miracles, but supercharging at low boost is probably the least risky version of FI.

I've seen a couple let go with no boost at all, its a total lottery. Some of the US cars are running 400+ bhp on stock rods and I think the TD dev car is currently running ~380bhp on a stock engine.

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The problem isnt as simple as at X BHP a rod will go.

I got speaking to Mike at TD, he was explaining it was more about peak cylinder pressure. This is something that Supercharging has an advantage over turbo as it increases in a linear fashion where a turbo nowadays can push to max boost early on in the rev range. As the car revs up the peak cylinder pressure naturally drops off.

The rods are also sintered which produces an irregular output hence why it is a lottery.

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19 hours ago, matrixprotein said:

Abbey have stop using em over issues with heat management

Only really an issue on track. Still enjoy mine after 4+ years boosted. The charge temps do get hotter than the rest but it is relative, the newer SPS version is apparently better and adds a little extra boost per pulley. The problem is that the cost of a new one means that often people will go to other alternatives, just look at the current discount of the clearance CW or how good value the TD turbo kit is. The Harrop, also being from Aus, is equivalent in price and produces "better" results and does have better heat management.

For a road driven car the Sprintex is just fine. 70mm pulley it makes a lovely whine and puts out similar power to the Cosworth - I reckon mine is ~250-260 hub bhp, so right at the limit of what most would consider "safe". If I were to track it, the output would drop a bit over time as the W2A system heats up, but I'm still not sure it would ruin my fun. A WMI kit soon sorts that out.

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7 hours ago, DevilsCry said:

MIne's got Harrop's and it does not really whine.

Then install aftermarket gearbox/tranny/diff bushings, so that other parts will whine in place of quiet supercharger :)

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The Sprintex definitely has the best whine, its sound is completely infectious. I had one on my CR-Z and it's an excellent linear unit and pretty bomb proof.

There is no doubting that it gets hot, though. Once I got a vented bonnet then the problem went away, as plenty of cool air flowed over it and boost didn't drop even in the hot summer.

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The Sprintex definitely has the best whine, its sound is completely infectious. I had one on my CR-Z and it's an excellent linear unit and pretty bomb proof.

There is no doubting that it gets hot, though. Once I got a vented bonnet then the problem went away, as plenty of cool air flowed over it and boost didn't drop even in the hot summer.

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How do you even clean a car with a vented bonnet xd

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I was just watching the harrop video. Putting all forged internals aside, they reduced pulley size and got the car up to 380bhp.

I know cosworth do their 10% smaller pulley but is it simply reducing its size that's required to get additional boost?

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29 minutes ago, matrixprotein said:

I know cosworth do their 10% smaller pulley but is it simply reducing its size that's required to get additional boost?

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Yes it is or over-sizing the crank pulley is the other way. The tough issues is insuring that the intercooling is up to the job as there will be increased heat generated especially if you start to over drive the supercharger. 

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There's a video thats on YouTube just been uploading by some Aussies. Who have had their rods go at about 400bhp. Pretty interesting watch as they take apart the engine and show you.

If I remember where on YouTube I'll post a link.

I know I'll go supercharger route but thought hmm if I went harrop and eventually wanted more power to do internals and then ask if harrop could make their smaller pulley. Haha now I'm dreaming

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One thing is minding engine only. Imho our engine should stomach some 300whp and higher without any strengthened components. But there is also tranny side. Very possibly at very least higher rated clutch won't hurt to not slip with increased torque, and stock gearbox .. was it 4th or 5th that granaded for several of higher boost builds? If one tracks car and has forced induction, i'd also think of BBK.

I guess, cossy decided to limit boost with stock pulley exactly because much more accompanying mods at higher budget would be needed if one wants reliable / safe overall result.

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