Well, what kind of heads are you advising ?? Spec C ? But with higher RPM turbo will have a difficult job...

 

John,

Increasingly I am seeing people say that turbo XYZ is too small because it chokes at 5500, 6000 or whatever. I don't get this. Too small for what exactly? To me the ability to maintain power to 8000rpm (or whatever) means flexibility, not being forced to change gear and so on.

Shootout will reveal some interesting and varied setups.

Paul

 

I think 2200 RPM before the rev limiter for peak power is a bit early, very flexible yes, but the standard car peaks 1400 RPM before its rev limiter. I think we are asking a bit much from a TD05 exhaust housing and turbine wheel, it just gets octane hungry, we're only talking about 1.1 bar at the very top here.

 

Paul, sounds like Im not the only one who want to hang on to the power curve for as long as possible.

 

If you want to max out a turbo in the midrange, it will always drop power at higher RPM while the max flow capacity of the turbo is reached (and VE of the engine is dropping)! If you would use for example a TD05/06 20G at 1.0 bar, I think it will give max. power at about 7000 RPM on a 2 liter. I don´t understand why you would have max. power at a higher RPM, it is only possible if you sacrifice midrange.

P.S. It could also be the case that the turbine is too small compared to the compressor, than you will see quite a drop in power at high revs because the ignition has to be retarded quite a lot to keep it det free.

Mark.

 

I fully understand the reasons why it happens, I am just not so sure it's such a bad thing, provided you get a good usable power band.

 

It is just turbo sizing, I would have thought I tend to go for something too small and screw the ***** off it, not usually suggested I go too large

 

it depends where you want to make your power really does it not?

David

 

That's not the sort of attitude I expect from someone as respectable as you, a Doctor for heaven's sake!

Paul

 

Mark

Yep, bigger 14mm bolts and retapped block. Just decided to go bigger after all the troubles so the ******* would'nt come loose

 

There is some debate as to whether my setup can ever be a reliable daily driver.

So far I've had the headgaskets fail (but Scott had this twice with head studs), exhaust manifold has cracked. The clutch and 6MT seem to be doing alright.

9000 miles on the engine so far and it feels brilliant.

An honest 450/400 on an iON turbo which is more than big enough for the job (hopefully at 1.3 bar) seems sensible enough to me given that most of the use is on a scamera infested cruise anyway? 180BHP/litre - can it be reliable? With the occasional foray to 7500 RPM?

Would you do a preventative rebuild of the engine with stronger internals or would you see if it breaks?

Personally I was just going to try it Happy to pay if it breaks and have another car available at short notice.

 

John, you are the absolute contrast of a friend of mine, who is a GP, he is happy to drive around in a Citreon C2 1.4

 

lol..

It has to be said I really cannot see my doctor getting in anothing other than a shopping trolley let alone doing what you have John.

You must get some really classic comments on call outs etc..

Simon

 

john.. fix it when it breaks.. if it aint broke dont fix.. give it a while for the groupbuyers to realise whats involved and pick one up for a bargain..

I dont think the block is up to too much power.

PS how do proven and honest HP's compare? like US and UK?

David

 

I suppose we are talking UK figures then

What do you call "too much"? as you are far more power hungry than I My "too much" would be 500, yours would probably be more?

Seems odd to me to start changing things when we don't know what the weak point is yet.

 

Who built the engine for Scott's car? Was it down to procedure or what??

 

The official ARP procedure was used for my original build, but I don't know if the torque wrench was recently calibrated. When they came off they were all similarly loose, to about 50 to 60% of the specified torque IIRC. However, Quirt Crawford who designed them for the Subaru application said there was no issue with them. After Scott's very similar story I didn't want to risk it again to the point that when I heard I had the engine stripped again having been rebuilt to swap to bolts. The bolts don't seem to be a problem, so another thing maybe I was trying too hard to "improve". A mystery I suspect.

 

500 isnt too much... 600 isnt too much.

when you get proper levels of torque, they arent enough..

Question is where do you go???

800+ bhp

David

 

450 BHP please. Says so in my thread title

 

It would be very simple to start another thread with a revised title

 

Daily driver 2.5 project - target 650 BHP/600lbft reliable

Like This? Won't be long eh John?

 

more like 700 with a little bit bigger turbo

 

LOL.

The P450 is further delayed (ordered 48 hours after Prosport dyno day), so we'll keep the 450 target for now

 

and there was me thinking the 450/400 target was built around a warranted gear box , clutch and an engine with uprated internals. now you have an untested standard block with a standard box and clutch rated to 340lb/ft

lets hope it is not rod failure due to the 7500rpm limit , be a shame to loose those pavlo heads and the ion core.

still , it would give me chance to use my new tow bar

 

LOL

 

The standard box has taken far more punishment than the guaranteed one though, I am only running a third more torque than stock on a car that weighs 200kg less. So it has a chance? What alternative can I use for a road car?

RCMS recommended the clutch to 440 lbft though and Harvey's 10mm smaller diameter version of the same seems to handle 464 lbft. There is an alternative that handles another 10-20lbft, they recommended not to bother.

Axis are using the standard rods with CP pistons for a 7500 RPM limit.

I am a hooligan but not like the guys running 2.0 bar and higher rev limits in the US and getting away with it.

So I'm running a 2.5 engine and box at 33% more torque than they are designed for to OEM warranty standards with 10000 mile oil changes, regular gas, cats and 3 year gearbox oil change intervals. Hardly makes me a mad irresponsible modifier does it?

Meanwhile many routinely run a UK engine and box at 40% more than they are designed for, the engines have a laugh at that, and the boxes sometimes last at that level but are a very old design notorious for breakage with small gears, no gearbox oil cooler and poor case rigidity.

 

Yeah on their VF22's LMFAO..

since when did the 6psd have an oil cooler?

David

 

RCMS now have an AP twin plate combined with a 5.2kg flywheel which will handle 500 / 550 lbs/ft so at least the clutch is available for the next stage

Hope the Ion arrives soon - it'll be interesting to see how it performs on a 2.5. Do you have a lb/min rating for it?

 

Only 40% ?

Better start worrying then....

 

Callum

Available and fitted to my car