7A Exhaust Cam

[newsh]

Guys, how about a laymans guide to the numbers and what they mean? and some of the terms, like exducer?
I've only been driving turbo quattros for 20 yrs and I don't know squat.

I take it the stock S2 turbo is a kkk K24. What's the RS2? What are the actual differences?

What would be the best turbo for making say 350 - 380 bhp but still boost up at 3k? (Sounds like Mark's hybrid?)

[Mark Halligan]

Mmm.. probably did'nt explain myself very well, what I was trying to say is that a turbo (whatever the make) with an exducer bore the size of Doug's, i.e. around 56mm would spool up a LOT quicker than the present 4.2K rpm with the ceramic bearing option fitted, based upon, mine being 63mm and producing 1 bar at 3k rpm, both with #8 hotside, although mine has been 'altered' slightly , its started out a #8 and the work done to it (bigger exducer bore) would theoretically slow the spool up down?

Mark.

[Mihnea]

On a real K26 @8 it is 56mm or thereabouts, Doug, what about measuring it so we know once and for all BTW???

FWIW, an RS2 K26 #6 exducer bore is 54mm.

[Mark Halligan]

Mihnea,

help me out here, what size is the exducer bore on the K26 #8 hotside?

Mark.

[Mihnea]

Mark, you're cheating man your exducer bore is as big as a KKK27 #7 hotside, same as the one used in sport quattros

but yes, ball bearings are cool, but beware of the big bad surge line!!!

[Mark Halligan]

Gents,

I know that this started off about the 7A cam, but its sort of turned into a turbo discussion.
I feel I must point out that it IS possible to get a relatively quick spool up with less lag using the #8 hotside.
The turbonetics T3/T4/KKK hybrid fitted to mine has the ceramic ball bearing option and I have 1 bar at 3k rpm and a mentally fast spool up from then on, I believe this is a good part of the reason why the power delivery has been described as 'brutal' by a few people before, this is quick, especially because I am also using a large turbine at 63mm (turbine housing reworked to take it) which you would think would slow it down even more?

I suppose what I am trying to say is that there is more to life than the KKK, nowadays there really is so much available, that we are not so limited in our choices of turbo.

Josh said:

So much to learn!

Too right brother , there definately is, but its fun doing it (if not a bit expensive ).

It's too soon for me to comment upon the longevity of the ceramic bearings, but but if you want a quick and hard spooling turbo, they'll do it for you.
Like I said I am still learning, so if I'm talking ******** please tell me, but be kind when doing it...........its Christmas .

Regards,

Mark.

[Josh-stateside]

Thanks Mihnea


So much to learn!

Cheers
Josh

at least I am on the right track

[desmo888]

Originally posted by Mihnea
Dave,


Don't, I'm saying don't ever put a K26 on your engine. a K26 can only do about 290 HP with MUCH MUCH MUCH more lag than a K24, thus it's not really worth it.

Depending on the octane rating that's available where you live, 300 HP is more or less a dream on a K24. Personally, I've never done more than 280 HP on a K24, and that was already running pretty close to its reliability limits, but not beyond. My advice: use the stock turbo for now, then when you have the dough, get yourself either an RS2 (370 HP are possible) or a K26/27 or K26/27/29.


HTH,

Mihnea

THANKS Mihnea!!


That is what I needed to know. Of course I do not understand the designations of the turbos you described but I will when the time comes.

[Mihnea]

Originally posted by desmo888
What about this unit?

http://cgi.ebay.com/ebaymotors/ws/eB...category=33742

********e, it has an integral wastegate and thus you can't use it on your 3B. Chances are also that it might even give less HP than the stock unit!!

[Mihnea]

Dave,


Don't, I'm saying don't ever put a K26 on your engine. a K26 can only do about 290 HP with MUCH MUCH MUCH more lag than a K24, thus it's not really worth it.

Depending on the octane rating that's available where you live, 300 HP is more or less a dream on a K24. Personally, I've never done more than 280 HP on a K24, and that was already running pretty close to its reliability limits, but not beyond. My advice: use the stock turbo for now, then when you have the dough, get yourself either an RS2 (370 HP are possible) or a K26/27 or K26/27/29.


HTH,

Mihnea

[desmo888]

What about this unit?

http://cgi.ebay.com/ebaymotors/ws/eB...category=33742

[desmo888]

On the subject...

I have a K24 with 235k miles on it (or at least on the car it was removed from).
There was no problems with it when it was removed removed from the 200TQ. The orevious owner had the car for 3 years in which time he had NOT had the turbo rebuilt.

The shaft is very tight and everything seems to be fine. I am not sure which direction to go when I install my 3B engine in my Coupe.



1. Put the K24 on as is

2. Have the K24 rebuild and install it ($350-$400 quoted)

3. Buy a lower mileage K24 ($125 quoted)

4. Buy a lower mileage different turbo (K26???)

I am going for a daily driver with about 300 hp. Upgrades later are possible (to 370 hp or so).

Any suggestions would be appreciated.

[Mihnea]

Originally posted by Josh-stateside
I'm curious about this too.


The idea is that the 7a cam will push more exhaust gasses through which will spool the turbo faster. Isn't it like having more displacement? I am thinking for this applications something like a k26#8 hotside housing with this cam will make it feel more like a k26#6 with stock cams?

Lately that's the direction I am thinking of heading.

Seemingly this cam is not necessary with stock applications or a k26#6 in my opinion.

It's not a matter of how much horsepower it can produce but rather how much it can compensate for the slow spool of a larger exhaust hot side housing and turbine?

Not to get too technical. But it's nice to say the actual reasons it might help vs just saying it will add more hp.

I don't know.. Still learning but thats how it makes sense to me.

Cheers
Josh

Josh,

A K26#8 turbine will still remain a #8 turbine and won't make much boost below 4k RPM. Ask Doug, his was only working from 4.2k and I hope the 7A exhaust cam will reduce this a bit to about 4k.... the #6 turbine makes good boost at 3.3k and full boost from about 3.5k RPM-on.

So, if you're after pre-4k performance, definitely go for a #6 hot side, if not, #8 is for you


Cheers,


Mihnea

[Josh-stateside]

I'm curious about this too.


The idea is that the 7a cam will push more exhaust gasses through which will spool the turbo faster. Isn't it like having more displacement? I am thinking for this applications something like a k26#8 hotside housing with this cam will make it feel more like a k26#6 with stock cams?

Lately that's the direction I am thinking of heading.

Seemingly this cam is not necessary with stock applications or a k26#6 in my opinion.

It's not a matter of how much horsepower it can produce but rather how much it can compensate for the slow spool of a larger exhaust hot side housing and turbine?

Not to get too technical. But it's nice to say the actual reasons it might help vs just saying it will add more hp.

I don't know.. Still learning but thats how it makes sense to me.

Cheers
Josh

[Mihnea]

Greg, this works like this and some people even use both 7A cams, so I wouldn't say it's THAT bad.... the overlap is minimal and having cams with 0 overlap is virtually impossible... also, don't forget that once the engine is at high RPMs and also due to lifter clearances, the static duration/lift are a bit messed up....