Twincharging discussions.

[NitroDann]

Warren have you guessed who will be supplying all my internals and machine work yet?

I intend to run it blown first, then add the turbo, I can do all sorts of silly stuff with it in the meantime. Including the pre charger WMI (water-meth-injection). I may run it non intercooled in the mean time, but I want to do a V mount as a fabrication and show off exercise.

Im truly surprised that you got 400hp flow out of an SC14. What fuel was it on? Straight methanol? Also whats the reliability of an SC14 spun at 25,000rpm or whatevers needed to get that sort of flow out of it?

Dann

[wozzah1975]

Warren have you guessed who will be supplying all my internals and machine work yet?

I intend to run it blown first, then add the turbo, I can do all sorts of silly stuff with it in the meantime. Including the pre charger WMI (water-meth-injection). I may run it non intercooled in the mean time, but I want to do a V mount as a fabrication and show off exercise.

Im truly surprised that you got 400hp flow out of an SC14. What fuel was it on? Straight methanol? Also whats the reliability of an SC14 spun at 25,000rpm or whatevers needed to get that sort of flow out of it?

Dann

With the E85, you shouldn't need to run any water/meth injection, I would only do that if you intend to run pump fuel (eg: 98).

The engine was a hillclimb engine, so it only ran in short bursts, but having said that we had no supercharger failure at all (apart from when some valve heads went through one, but thats another story!). I can't remember off the top of my head how hard we were turning the engine, or what ratio's we had on the pulleys. The guy that did the developement work will have it documented. From memory it was around 12,000rpm engine, and a slight overdrive on the supercharger.

In relation to the horsepower, the engine was very highly strung. it ran 35mm inlet valves and 30 exhausts (compare that to a std BP!) and big lift cams, and had countless hours of work on the cylinder head (basically a complete redesign of everything, including milling out ports and rewelding in custom units), plus 40lbs boost at times. The fuel we used was a direct copy of Shell "A" racing fuel, which was straight methanol, castor oil (5% from memory) and Acetone (10% from memory). The Castor oil is used to lubricate the blower rotors, and the acetone is used to bring the octane rating back up after the castor oil is blended. I can't remember the compression ratio either, as we toyed around with different boost/comp ratio combinations, but I am sure it was still reasonably high, even with the big boost. It was a hell of a lot of work. These engines are well renowned for making very large horsepower figures in N/A form in the drag racing scene, 400+ horsepower to be exact (thats right, N/A form, no puffer!). The car was a handful, 400kg and 400ish horsepower

Cheers,
Woz

[dbr]

What crankshaft are you planning to run?

[NitroDann]

Prep'd stock.

Stock oil pump, external reg.

Ebay rods/ supertech pistons

Arp

Acl bearings

Whatever headwork/cam combo warren recommends, but I imagine 285ish degree, plenty of lift wide lobe seperation angle.

Probably around 45mm quads with a large plenum in a simple design.

Small maybe stock primary injectors in the head with large pre blower secondaries. That should keep any cylinder/intake manifold flow variances correctly fueled.
Looking at low mount hotside blower with a very forward top mount turbo setup, behind the headlight. Really big hotside A/R.

Dann

[dbr]

Could you suply any details of the preparation of the standard (already hardened) crankshaft. I have herd of people cracking these at lower torque levels than you propose. Higher reving engines (8500rpm) have also cracked their cranks with lighter conrods and pistons than you will be running.

Will you be running the link processor again? I assume it has gennerous tip-in spark retard authority that you can use while you wait for the fuel to get from your secondary injectors to the cylinders.

[NitroDann]

Can you please provide links to said crankshaft damage?

Just lightened and balanced, and machined for fresh bearings.

I wont be using the link, that died in the fire, Ill use MS.

It wont need generous tip in settings because it will have a throttle body just before the injectors-before the supercharger. But if I needed more tip in there are people who can modify the code easily enough.

Dann

[gslender]

But if I needed more tip in there are people who can modify the code easily enough.

...and I be one of them monkeys who can do that for ya ;-)

[NitroDann]

you would be one of the people with skill enough to extend the range of lean tip in yes...

Dann

[dbr]

I don't have any links to stories about crankshafts. The conversations occured off-line in that other world.
I have had the same story from a copuple of sources, but the most prominent was the local machine shop where I had a block machined. He pointed out that a few of his other MX5 customers had cracked crank shafts. Although, I know two of them, I should not publish their names here without their permission. However, they both race, one in baby Sports Sedans and one in Marque Sports Cars.

[wozzah1975]

I don't have any links to stories about crankshafts. The conversations occured off-line in that other world.
I have had the same story from a copuple of sources, but the most prominent was the local machine shop where I had a block machined. He pointed out that a few of his other MX5 customers had cracked crank shafts. Although, I know two of them, I should not publish their names here without their permission. However, they both race, one in baby Sports Sedans and one in Marque Sports Cars.

I've have seen the same, but only on the 1.8, may be a problem on the B6 as well. Went through 3 cranks before I found a good one for my build. Crack test it before you machine it Dann.

On the 1.8, there is what looks like a heat stain in the cast, even on a new crank. It's usually near no4 bigend/no5 main journal. It is a result from what ever treatment they give them from new. It is a weak spot on the crank, and it is a problem even on a new crank (whilst i haven't personally seen it, they have tested cracked from new).

Cheers
Woz

[NitroDann]

Ok Ill get warren to have a look at mine.

I wonder why this has never been mentioned to me before.

What are the implications and cause of the cracks?

Dann

[wozzah1975]

Ok Ill get warren to have a look at mine.

I wonder why this has never been mentioned to me before.

What are the implications and cause of the cracks?

Dann

I hadn't heard of it either mate, it was pointed out to me by a mate who does alot of BP engine builds for race cars a number of years ago.

Whilst neither of us have paid money out to investigate why they crack there, we are both of the opinion that the stain from the heat treating would indicate a problem in the process. On a really bad crank it almost looks like the crank has ran a bearing at some stage (the blue tinge!) and been remachined, but a new crank looks exactly the same. The cranks with lighter staining almost always are the ones that aren't cracked.

A cranked crank will eventually break, especially when stressed. It may run forever in Nana's car though!

Cheers
Woz

[NitroDann]

I wont stress mine, it will mostly spend its life under 400RWHP.

I only want over 400rwhp for one dyno sheet.

Dann

[wozzah1975]

I wont stress mine, it will mostly spend its life under 400RWHP.

I only want over 400rwhp for one dyno sheet.

Dann

[NitroDann]

Come on then, give me a spec sheet for internals on a BP4w build as you would do it.

Do it.

Dann