Few questions about BIG turbo conversions

[Grant]

I have a few questions about big turbo conversions.

The A3/S3 has forged pistons, conrods and crank as standard. However, the conrods seem to be the weak link in the engine. Is it the actual conrods themselves or is it the rod bolts that are weak over 335lb-ft?

Also, why has nobody gone for more than 340bhp - there are turbos out there like the GT28R (good for about 370bhp) or T30 that is good for about 470bhp.

Surely with uprated conrods it would be possible to get over 400bhp safely - no?

 

[Ess_Three]

[ QUOTE ]

The A3/S3 has forged pistons, conrods and crank as standard. However, the conrods seem to be the weak link in the engine.


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Apparently so...
Although to what degree, I'm unsure.


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Is it the actual conrods themselves or is it the rod bolts that are weak over 335lb-ft?


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It's the small end of the con-rod.
I've seen bent rods...only the small end goes...where it meets the piston.

According to Mick Truluck of Jabbasport, the later 210 and 225 engines are reliably good for 300 lb-ft...whereas the earlier engines like yours Grant, are apparently a bit stronger.

I have to question his reasoning though...myself / David have been consistantly running over 300 lb-ft for years with no problems (no engine problems anyway!)

I've never heard the 335 lb-ft figure mentioned...unless that's the accepted figure for the earlier 210 engine?


[ QUOTE ]

Also, why has nobody gone for more than 340bhp - there are turbos out there like the GT28R (good for about 370bhp) or T30 that is good for about 470bhp.
Surely with uprated conrods it would be possible to get over 400bhp safely - no?

[/ QUOTE ]

I think you'll find Bill Brockbank is / was well over 400BHP on his Golf Mk4.

 

[Grant]

Ok, so it's the conrod itself that bends - anyone know where you can get steel conrods? Would stronger pistons and crank be needed also?

The 335lb-ft figure is mentioned on Jabbasport's website, under "Turbo Kits" then "Technical Spec".

 

[Ess_Three]

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Ok, so it's the conrod itself that bends


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Yup...bends the small end.
Not pretty.


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- anyone know where you can get steel conrods? Would stronger pistons and crank be needed also?


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Crank...no, not always. It's pretty strong.
Conrods will need uprating and lightening, pistons should be forged and lower compression if you are getting silly with power levels.

As for where to get parts...I'd speak (did) to Mick at Jabba...
Or Bill Brockbank at Badger5...


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The 335lb-ft figure is mentioned on Jabbasport's website, under "Turbo Kits" then "Technical Spec".

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That makes sense...
I have doubts about that figure though...my S3 apparently wouldn't take any more than 300 lb-ft...that has been proven to be incorrect.
Even the 335lb-ft 'limit' of the earlier engine I've ran very close to with no problems at all, engine wise.

 

[s3bow]

@ Imola, how much power you thinking of having ? MTM don't change any internals and theirs are 330 lbft. What turbo you thinking of using ?

Chris.

 

[RichA3Turbo]

If you are aiming for 400, best ones to use are the IHI VF22 or GT3071R (from what ive read on the net). The IHI VF22 is used on the Ex-Jabba golf (which is now on a new engine!) which was pushing a realistic 390bhp. Some say over 400, but again it depends on whos dyno. Either way, its one damn quick car. Its got a very tidy intercooler on it too...MASSIVE!

Rich

 

[s3bow]

That is indeed a nice intercooler. Neat welding and fab on the pipes too.

Chris.

 

[Rob W8]

I wont that one

 

[Grant]

I was thinking of 400-450bhp. I don't see the point in spending £4k or £7k in MTM's case to get 340bhp, where you could spend approx £3-£4k on a custom kit and get up to 400/450bhp.

The turbo I was thinking of was a GT30, however I'm unsure of spool up time for this turbo, maybe slightly smaller like the GT28RS.

Replace OEM conrods with Pauter rods and ARP bolts, new forged, lower compression pistons (lower compression from 9.0:1 to 8.5:1) and uprated valves.

Bill of Badger5 said:
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The valvetrain is a weakness on the 1.8T with failures of valve heads dropping, destroying the engine completely. We have uprated valves available in one piece nimonic stainless steel, black nitrided for inlets, and inconel exhaust valves which would give peace of mind for the top end reliability. Its pointless building a good bullet proof bottom end if the top end punches a hole in the bottom end when a valve breaks. (been there myself) - These uprated valves are £450 the set.

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Maybe I should wake up and stop dreaming... but I think it is possible to safely get 400/450bhp for the same price as the Jabba IHI kit.

 

[Ess_Three]

The HGP R32 wasnt/Isnt, neither is the HPA motorsport R32. Both of these cars are running in excess of 600bhp. Obviously there is alot that has been changed, but nothing drastic...only the basics. Its still using a haldex, other OE drivetrain. Maybe a 50/50 controller, but other than that and uprated thing like clutch, flywheel its all original. The S3 and R32 cant be far different can they? gearbox maybe slightly different, but all the other running gear will be identical or only slight differences. Sportec do a 450bhp conversion for the S3 which on a recent car, put out over 480bhp...it handles is fine.

Rich

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Indeed...
But what damage after a few years use?

I KNOW what was worn out on my S3...as does David who is having to contunue the trend of replacing knackered bushes, track rods etc.

Just because it works, doesn't mean it'll last...believe me...after 3 1/2 years I'm fully aware of what is starting to age / requires replacing.

You cannot take a chassis designed for 100 BHP engines and make it happy with 500BHP...you have to re-engineer EVERYTHING.
Will it wirk...year.
Will it last? Probably not...on smooth roads, maybe a bit longer than on the UKs finest back roads.

With regard to handling, power has nothing to do with it...i'm quite sure the Sportec conversion handles just fine...but that doesn't mean it isn't virtually undrivable.

320+ lb-ft of torque through an S3s drivetrain with a well sorted chassis is a handful...any more (I've tried 330+) and it's dangerous in the wet by virtue of the unpredictable Haldex control.

Anyone who actually drives a 500BHP/400+ lb-ft S3 is a better man than me...if for nothing else than for their ability to keep the damn thing on the road...the chassis isn't designed for it...and it won't do a particularly good job of coping.

Of course, if it's a straight line queen, or posing chariot, there will be no problem with bushes and track rods wearing out...
However, if it's a car that will be driven, in my view, the S3 in 270 BHP/300 lb-ft spec is already pushing the limit of the suspension and steering design spec.

 

[RichA3Turbo]

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With regard to handling, power has nothing to do with it...i'm quite sure the Sportec conversion handles just fine...but that doesn't mean it isn't virtually undrivable.

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Sorry.. I meant "it handles it fine" refering to the power, not the handling..I aint that silly /ubbthreads/images/graemlins/tongue.gif

I agree, it certainyl would need bits replacing on a monthly basis, but you cant get that much power from a car without having to shell out for worn/broken parts regularly... Which, I agree, does ask the question of "what is the point" when you could go and get a car with that much power from the offset and can handle it.

Rich

 

[Ess_Three]

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I agree, it certainyl would need bits replacing on a monthly basis, but you cant get that much power from a car without having to shell out for worn/broken parts regularly...


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Indeed you can...just as long as people know that a simple re-map won't kill the rest of the car...but once you go further, you get into changing clutches, tyres, track rod ends, suspension bushes and the like with alarming regularity.

There is a limit to what the standard stuff is happy to work at...above that you will be replacing fairly often.

[ QUOTE ]

Which, I agree, does ask the question of "what is the point" when you could go and get a car with that much power from the offset and can handle it.
Rich

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Good point Rich...but you are as bad as me...we all want our cars to be different and individual...so we modify and tune.
In that respect, there is a valid point...

But, there is also a point where an S3, for example, with 270 BHP and 300 lb-ft of torque is just as quick point to point, if not quicker, than an S3 with 400BHP and 400 lb-ft by virtue of the fact that it's earier to drive and doesn't try to spit you off at every opportunity.
The lower output car could be just as well set up suspension wise and braking wise, and be able to be driven pretty much flat out everywhere...the higher output car you simply couldn't do that...you'd be fighting to keep it on the road too much to concentrate on going quick!

The S3 is not especially predictable at high power outputs where the Haldex is being worked hard...lots of power and torque (too much) could make for a nasty car to drive.

Maybe a Haldex controller would calm that trait though...?

 

[robthehungrymonkey]

[ QUOTE ]


The S3 is not especially predictable at high power outputs where the Haldex is being worked hard...lots of power and torque (too much) could make for a nasty car to drive.

Maybe a Haldex controller would calm that trait though...?

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Probably irrelevant, but when QST put the RS4 engine in an S3 they also used the Torsion 4WD too. Would that be due to the above point? or is it because of compatibility

 

[Ess_Three]

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Probably irrelevant, but when QST put the RS4 engine in an S3 they also used the Torsion 4WD too. Would that be due to the above point? or is it because of compatibility

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Probably a bit of both!

 

[Ess_Three]

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I'd stick with 350/360bhp max on the stock tranny.Use a turbo that maxes at this level,there's been a few mentioned.Performance is never cheap and there are no short cuts.As Glen has stated a 270bhp 310lb/t s3 is a fast car.

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Personally, I think about 330 ish genuine and reliable BHP with approx 300 lb-ft of torque, but coming in slightly later and better regulated than with a max'd out K04, would make for the perfect usable S3.
You'd be able to actually put that power and torque down with minimal problems, and the car should be alive, but not a handful to drive.
This would have a big appetite for bushes and bearings though!...and probably clutches and tyres too!!

I honestly believe that in the UK, with out less than perfect roads, a 330/300 S3 would be faster point to point in the real world than a peaky 450/400 monster S3.