Turbo Tuning advice

[333pg333]

Hmm, methinks some old wives might be chiming in shortly. [] I'm always prepared to be corrected but I have never heard of pros building a new motor with used parts if they have the budget for the latest and greatest. Granted that there are always some commercial interests that come into play. However while I concede that certain treatments (hot and cold) are regarded in some circles as a vital processes I would assume that literally hundreds of thousands of impacts that the rods go through would not be considered a favourable heat treatment imho.

 

[George Elliott]

Patrick,
commercial interests are sure to exist and a new set of carillo's are a lovely idea - I am the first to admit it. They are light, strong, weight matched, etc etc

but in reality, they may not be absolutely necessary.

If a rod component has a 100 tonne tensile and compression load limit, and max torque / revs of a 400hp 2.5L equates to 40 tonnes, then the component is safe indefinitely. It will never deteriorate in that application in maximum load conditions. Porsche made engines like that at one time as you will know.

The day it all goes wrong is when the engine drops a valve - maybe during a missed gear change or a down-shift buzzes the revs to 8500+rpm. That may create 150 tonnes of load and the rod fails. Now if a carillo had 180 tonnes load limit in that application, then in theory it may not fail, but thats a carillo salesman speaking - commercial interest[8|]

George
944t

 

[nick_968]

Stay away from aftermarket (supposedly performance) headers and crossovers. For one most of them are untested. Secondly the SFR ones do not fit and will require almost as much work as getting a set made to get them to fit. If you are serious about this mod you are far better off getting a manifold made by someone here who knows what they are doing. SFR have also had some serious issues lately with parts delivery. The post turbo exhaust system is a far greater restriction that the manifolds.

 

[TTM]

When looking at FS threads on RL for SFR "Stage 2" headers they seem to always be sold by people who bought them new some months earlier but moved back to original headers.
They may be fine for stripped-out racers, but even then, lots of money to be better spent elsewhere before needing them, in my opinion.

 

[PSH]

Well thanks to everyone for all the comments and advice , I'll update you on my own thread when I get closer to the exhaust stage as to what I plan to do, as stated I'll now be using the recently acquired 3" Magnaflow for running in purposes. I also note the discussion in regards to stock vs after market rods and have continued with my research into what's best for my car. I've lost count now how many site's I've read about this subject and depending where you look you'll get different views, but when you step aside from a particular car and the various manufactures, offering their own products for said car and then look into the engineering arguments, things are not so simple. Rod design is critical for a given application, high revving, high torque, dragsters, endurance, I beam, H beam the list goes on and on. So after doing all of this research only one person can make the decision and that's me and although I'm no motor engineer/designer I am more than able to understand the various arguments put forward from all sides.
Therefore I shall be using the stock rods from the 86 year as they are what's best for my car's particular design of engine especially when considering, the intended power output, it's use and the endurance needed.
Oh one other thing I've learnt that i wasn't aware of at the time, I knew the 86 block was stronger and I knew that it's internals were forged but I didn't realise that Porsche also changed the later car crankshafts, I had assumed these remained unchanged throughout. Wrong, from what I've read only early N/A cars, 85/86 turbo and 968 turbo had forged crankshafts although some 87 models may also have them due to surplus stock left over.

you live and learn..

Pete

 

[George Elliott]

Look forward to your updates Pete,

the forged crank info is new to me, I thought they were all forged. I understood the rods went from forged to cast somewhere around the end of 1986.

The crank / bottom end is seriously strong in any event, I have never heard of a failure in that area. Its almost always a holed piston or clobbered valve that starts the fun.

George
944t

 

[PSH]

ORIGINAL: George Elliott

Look forward to your updates Pete,

the forged crank info is new to me, I thought they were all forged. I understood the rods went from forged to cast somewhere around the end of 1986.

The crank / bottom end is seriously strong in any event, I have never heard of a failure in that area. Its almost always a holed piston or clobbered valve that starts the fun.

George
944t

Yes I thought that too George, funny what turns up if you dig deep enough, of course your still relying on old info and who knows how many Chinese whispers may have got in the way along the line, but I found a couple of references to this so who knows. Certainly there's an awful lot of reference to using the 86 block if going for big BHP but no matter what components are used they'll all be for nothing if not set up by someone who knows what there doing, which reminds me, I must give Wayne a call, warn him of what's coming..

Pete

 

[944 man]

Cast cranks? Extremely unlikely Pete. I believe that all 944 cranks are forged, as were the 924s before it.

 

[PSH]

ORIGINAL: 944 man

Cast cranks? Extremely unlikely Pete. I believe that all 944 cranks are forged, as were the 924s before it.

My thought's too Simon, I guess only the designer from that era can answer if there were any differences, like you I think it's unlikely but that's the problem, who really knows..

Pete

 

[simon macturbo]

Exhaust -
does anyone run a screamer pipe - jap cars/time attack and the like run them - basiclly instead of the wastegate exhaust rejoing the rest of the exhaust it goes out a side exit to fresh air.
Any thoughts on this ??

Yes i know some tracks have very low db noise levels so this may be unacceptable

 

[944 man]

Screamer pipes dont offer any advantage, do they? Theyre just an easy way to dispose of the unused gas where large turbos are ditted with external wastegates.

 

[Tam Lin]

ORIGINAL: 333pg333

Hmm, methinks some old wives might be chiming in shortly. [] I'm always prepared to be corrected but I have never heard of pros building a new motor with used parts if they have the budget for the latest and greatest.

 

[Diver944]

ORIGINAL: 944 man

Screamer pipes dont offer any advantage, do they?

The idea is the excess gas being vented from the wastegate is normally plumbed back in to the exhaust line and therefore reduces the amount of flow that pipe can allow. With the wastegate venting straight to atmosphere it keeps the normal exhaust pipe clear to only cope with the gases from the turbocharger itself. I've eard the noise from out cars with the wastegate venting to atmosphere and it's truly horrific []

Lindsey sell a specific small silencer to bolt onto the wastegate to mute this exact nosie

 

[PSH]

ORIGINAL: Diver944

ORIGINAL: 944 man

Screamer pipes dont offer any advantage, do they?

The idea is the excess gas being vented from the wastegate is normally plumbed back in to the exhaust line and therefore reduces the amount of flow that pipe can allow. With the wastegate venting straight to atmosphere it keeps the normal exhaust pipe clear to only cope with the gases from the turbocharger itself. I've eard the noise from out cars with the wastegate venting to atmosphere and it's truly horrific []

Lindsey sell a specific small silencer to bolt onto the wastegate to mute this exact nosie

now this sounds interesting.....

Pete