con rod bending survey

[ovlov25]

My 2 pence worth

Probably causes of bent con rods (simplified)

1. Detonation through poor DIY tuning
2. Excessive boost (for standard internals)
3. Combination of above or (less unlikely) a faulty engine component.

I did ALOT of research on turbo tuning a few years back when I considered doing a turbo conversion on my old MX-5. Time well spent after seeing how badly a home brew turbo went on a friends car.

For me, at the very least if I ever decided to modify my T5 extensively I'd be looking at the following.

1. Fully progammable ECU, (Megasquirt? has this been done on a T5?) with extra sensors etc for EGT, oil pressure etc.

2. Uprated fuel system, bigger pump, injectors and uprated fuel lines. Not a rising rate regulator.

3. Engine internals. Forged rods and pistons would be a necessity.

Of course further mods compliment everything. Bigger turbos, more engine work, brake systems etc.

More realistically a good remap with a decent operator doing the setup, would IMHO be the safest way to get more power. Even at that things will get pushed on an older high mileage car.

[foggyjames]

I'm not aware that a T5 has yet been run on MS...but Audi 5-pots are, regularly, so it should be possible. One complication is that engines with even numbers of cylinders can run (nice and simple) wasted spark, whereas a odd-number engine needs a cam sensor to determine phase if you're to do coil on plug (and removing the dizzy is a good idea for spark power at high boost). Having said that, with what can be done with the factory management, there doesn't seem like a lot of point in going programmable. Sure, you have to slip Marco a few quid, but if you take him your final spec...it's a one-off payment.

I am convinced that for the more budget-minded tuner, forged internals are non-essential. Of course they're nice (stronger, lighter, more detonation resistant) if you have the budget, but it's not an insignificant sum, and I reckon 400bhp can be achieved from a late 2.3 T5 motor on standard internals...with the right bolt-ons, and the right tuning. Of course for 350+, going forged is the safe option...and what I'd do myself, probably.

The pump and lines may well be big enough (in the 740, we're choked with fuel - if we want to be - with 630cc injectors on otherwise standard fuel system hardware), but injectors are a must-have. You may well want to monitor fuel pressure, just to be careful...

cheers

James

[Chesh740R]

T5 engines have been run on MS, I just missed out on a complete MS 5pot setup that was for sale stupidly cheap considering the amount of head scratching and modifying of the guts to get it to work. Strangely enough though the guy was only selling it to fund the purchase of an off the shelf ecu system.

Hence why i'll go down that route with something thats allready out the box ready to go, and i'll try and see how far i can tune a scrap standard engine before it explodes, which reminds me i need to speak with ryan about an engine.

[foggyjames]

If you want his, it's sat here, waiting for you...the rest of the car goes on Saturday, I believe, but the engine will remain.

cheers

James

[alistairolsen]

So are the rods in the 2.5n/a the same as the t5 rods? in which case is anyone aware of a known safe rpm for them, or for the bolts? (for instance what do aftermarket chips allow safely?)

[tc]

I got told that the rods have the same part number for the older and newer engines.

[foggyjames]

VADIS appears to show the same part number for 850R and 850 T5 engines...but...it is a part number which supercedes another. It may well be that the older part number is the 'skinny' rod.

In the case of the older Redblock engines, when the 'big' 13mm rods came out, you could no longer buy the 'skinny' 9mm rods.

cheers

James