I need help ! AVY at 8.000 rpm

[unora]

My GTi is putting 159 bhp at 7480 rpm, it cuts at 7.500 rpm so I think It can go futher, perhaps It can reach 8.000 rpm but I read in this forum that valvetrain can not.

Does anyone knows what I need to change ? Springs perhaps ?

I am loosing my mind in next step trying to choose between ITB or supercharging.

Thanks in advance.

[nfbr]

Sorry i cannot answer your question, but out of interest, what work has been done on the engine to give you near 160bhp?

[luke's lupo]

pritty lairy cams for a start Al

Edited December 21, 2006 by luke's lupo

[Dubya]

You don't need to change anything mate. The 'speculation' about the rockers is all bull... The valve train will more than handle 8000rpm style="vertical-align:middle" emoid=":)" border="0" alt="smile.gif" />

Edited December 21, 2006 by Dubya

[Tigz™]

Will the rest of the engine Dubya?

What would be the problems with a high rev limit?

Need to decide on one for the 1400.

[unora]

Sorry i cannot answer your question, but out of interest, what work has been done on the engine to give you near 160bhp?

BMC CDA. 4-2-1 exhaust manifold, camshafts and custom remap. I was thinking about port and polish head the cost is high and gain is low.

Dubya, Are you sure ? Reading VW Motorsport pdfs, motors in Lupo Cup championship reach 8.500 rpm but isnt explained if changes are made on valvetrain.

Edited December 22, 2006 by unora

[Clouseau]

the gti engine would be a pile of crap if it couldn't take 8000rpm as standard block. most NA engines from over 10 years ago should easily take 8000rpm without having to strengthen any internals. unless they are made by a poor manufacturer.

[Dogwood]

You don't need to change anything mate. The 'speculation' about the rockers is all bull... The valve train will more than handle 8000rpm style="vertical-align:middle" emoid=":)" border="0" alt="smile.gif" />

You absolutely sure about this ie. can you back it up?

I had a lengthy conversation with the Schrick people at Autosport last year and they said the reason they don't do any cams bigger than they do is because the standard roller rockers are made from rubbish and cap engine revs at 7800 max.

[Dubya]

You absolutely sure about this ie. can you back it up?

Think about it logically for a moment. VW design a motor to be run by everyone from your gran to your spotty faced boy racer, and each motor is good for atleast 200k miles. For this reason, everything is massively over engineered for what it needs to do - look at the openings in the head for a start. Basic engineering tells you, that if your stock motor needs to run at a reliable 7k revs for it's entire life, then the safe working load of the rockers and head assembly HAS to be 9/10k revs. If it wasn't, you'de be rebuilding the head every few 1000 miles! (if it couldn't rev to 8k revs, your rockers would be weakening every time you revved it to 7k revs).

The only limiting factor on the GTI motor for making it rev, is the weight of the crank counterweights. For it to rev more, you need to reduce the weight - sacrificing idle smoothness, for revving ability.

My NA tuned GTI runs custom cams, and a 7500k rev limit. Do you not honestly think I'd be running that, if I hadn't researched it before hand? Rothe Turbo conversions run stock head internals - and they now have to cope with boost pressure! The 20v motor, will run a massive amount of boost and rev to 8/9k revs reliably, with very little work. Turning the limiter up, so that your GTI motor will rev another 1000 revs is **** all in terms of motor stresses.

Like matey says, if the GTI motor couldn't do it... There'd be little point in having a GTI motor to begin with.

style="vertical-align:middle" emoid=":)" border="0" alt="smile.gif" />

[Jez]

I thought the Stock revlimiter was 7200 in the lower gears? my rev counter sails past 7k on stock ecu?

A poorly selected downshift when the brakes are dead will see the motor doing a good deal more than 8k!

on a motor that might touch 8k every now and again may very well be ok

but if its going to be doing it very often and exceeding it, is a totally different story

Also the same reason i thought that the motors in the lupo cup used different heads?

and ive never seen a Berg cup car with a lupo head!

Shall i post pics of the inside of the head of the polo gti motor i took apart? some of the tappets were in the sump....

[noddy]

I thought the Stock revlimiter was 7200 in the lower gears? my rev counter sails past 7k on stock ecu?

A poorly selected downshift when the brakes are dead will see the motor doing a good deal more than 8k!

on a motor that might touch 8k every now and again may very well be ok

but if its going to be doing it very often and exceeding it, is a totally different story

Also the same reason i thought that the motors in the lupo cup used different heads?

and ive never seen a Berg cup car with a lupo head!

Shall i post pics of the inside of the head of the polo gti motor i took apart? some of the tappets were in the sump....

i thought that the cup cars ran the head off a polo 1.4 16v (sorry dont know engine code) as the valve train was stronger than the lupo and polo gti's style="vertical-align:middle" emoid=":confused:" border="0" alt="confused.gif" />

[Jez]

i thought that the cup cars ran the head off a polo 1.4 16v (sorry dont know engine code) as the valve train was stronger than the lupo and polo gti's style="vertical-align:middle" emoid=":confused:" border="0" alt="confused.gif" />

Yea

all the pics ive seen of they do yea

[nfbr]

i thought that the cup cars ran the head off a polo 1.4 16v (sorry dont know engine code) as the valve train was stronger than the lupo and polo gti's style="vertical-align:middle" emoid=":confused:" border="0" alt="confused.gif" />

As far as i'm aware the UK lupo cup cars were all 1.4 16v's anyway

[Dubya]

A poorly selected downshift when the brakes are dead will see the motor doing a good deal more than 8k!

There is no rev limiter active on down shift. Select the wrong gear at the wrong time, and it'll just scream it's head off... literally.

I was led to believe the cup cars ran a tuned 1.6 AVY GTi motor with 170 hp, and revving to 8500rpm. The motor itself being made up of original VW parts, and running ACS management. That's my understanding of the regulations, anyhoo style="vertical-align:middle" emoid=":)" border="0" alt="smile.gif" />

[unora]

There is no rev limiter active on down shift. Select the wrong gear at the wrong time, and it'll just scream it's head off... literally.

I was led to believe the cup cars ran a tuned 1.6 AVY GTi motor with 170 hp, and revving to 8500rpm. The motor itself being made up of original VW parts, and running ACS management. That's my understanding of the regulations, anyhoo border="0" class="linked-image" /> border="0" alt="" />

[unora]

As you can see, AFH has not camshaft adjustment valve (N205) because has not variable distribution, and if you read VW Motorsport pdf about Lupo, you can see a photo of the motor in which shows this valve:

border="0" class="linked-image" /> border="0" alt="" />

So my question is: If the roller rocker fingers put the limit to 7.500 rpm ... Does exist any replacement for them ? style="vertical-align:middle" emoid=":coffee:" border="0" alt="coffee.gif" />

[LINCOLNSHIRESLUPOGTI]

My Gti revs to 8000rpm with the throttle bodies and the internals are standard (apart from headwork but that is irrelevant to rpm). I would like to add some more clarity to this discussion though.

While it appears fine to rev the AVY to 8000rpm I think the main issue is the cyclic fatigue life of the rotating components. They may well be able to take the rpm but I am certain that higher rpm will lower the fatigue life of the parts meaning you may well see an engine fail much sooner than with lower rpm. Put basically...where as we expect our engines to do 150,000miles, do we really think they would last that long if we drove them flat out in first gear all the time. Obviously not, the engine would carry out far more revolutions making the milage it would reach much lower.

So yes 8000rpm does seem fine, but perhaps you should expect an engine failure at a lower milage than the "average" lifespan of the same engine.

[ArosaMike]

I fairly sure it will rev to 8 or 8.5k but as Lincolnshire says, engine life will be reduced quite a bit. Increasing the revs into the 7s is generally fine and probably won't have much of an effect on engine life, but it's a fairly well known fact that due to the frictional forces in an engine, past 8k you run into a few problems as engine wear increases pretty dramitically past this point. If you're happy to face the prospect of rebuilding it at some point during your ownership then it's fine. It wouldn't surprise me if the Lupo Cup cars did indeed run to 8.5k but then they probably would need rebuilding after maybe 20 or 30hrs which is actually very long as race engines go.

[Dogwood]

Not wishing to rain on anyone's parade or anything, but i've seen an awful lot of totalled so called race engines that were built on the assumption that the OE manufacturer had built a substantial safety margain into standard components.

Applying some of the thoeries in this post to a CTR motor would have it revving to 10k no worries. So how come i've seen plenty go bang in race conditions using standard revs. And that will be why most teams running a CTR have a space motor sat in the van just in case.

You will no doubt get away with limited use ie. road work at say 8k for a GTI motor on most occasions.

I'm only quoting from a conversation I had with an expert in the valvetrain field who is familiar with the product.

I've also had a few good chats with the bloke who ran the BRC Polo S1600 cars. They revved to 9250 (standard crank by the way) but only after alot of re-engineering of the valvetrain.

Throwing money at an engine built on assumption and so called logical thinking rather than knowledge and facts is foolish imo.