40 replies to this topic

[KernowCooper]

Okay, aside from having my mind slightly blown by the second half the first bit made sense, I think.

So lock up is the point where you have full drive engagement, thus adjusting the convertor for higher lock up would mean you could figuratively slip the clutch longer to give you drive against high load until the engine came 'on cam' ?

Or am I miles off?

Unless anyone has bulit or knows otherwise I'm guessing I'll have to use a slightly sporty (1500-6k) cam like and SW5 or a 274SP to get the sort of numbers I'm aiming at.

Spot on
So lock up is the point where you have full drive engagement, thus adjusting the convertor for higher lock up would mean you could figuratively slip the clutch longer to give you drive against high load until the engine came 'on cam' ?

[Ethel]

Or forced induction, more cc's or nitrous. Performance is about getting more oxygen into the cylinders in a period of time so you can burn more fuel - more in each filling of the cylinders or more fillings.

[Skortchio]

Funny you say that Ethel, I was pondering the turbo idea.
I can lay my hands on a pretty fresh 1293 - rebuilt about 18months ago but not used, so the engine build cost could be put into a turbo set up.
How they would work with an auto I'm not sure but I would imagine fairly well as the car would have normal drivability before boost.

Don't know if any convetor or whatnot changes would be needed though.

[KernowCooper]

Your turbo application normally has a reduced compression ratio so i effect be a very soft engine at idle, be interesting conversion mind you but would take some careful planning on the correct air/fuel ratio

[Minidarren83]

I am by no means even remotely qualified for this topic but would a sc be best for this application as boots is produced from the off so a soft engine at or around idle wont be an issue or am I wrong? Lol either way dibs on first ride please Dave 100bhp+ auto mini hell yes

[Skortchio]

Haha, sold Darren!

It won't be a 100bhp mini though, 100ftlb perhaps - much more exciting!

I've been having a read up on low boost turbo set ups, a notch above the old MG turbo but still sub 10psi mostly. The advantage of them is they don't require any great engine work or modification and run fairly stock comp ratios, which would keep the inital pull away a bit more normal. Plus because they run smaller turbos they spool up fast coming on tune lower down which lends itself well to my modest rev range.

I know less about SC than I do about turbos and that's saying something. Not sure on the relative costings and adaptations needed for them, if only there was an "Idiots guide" book.
And to think I started out just wanting a camshaft.

[MRA]

WIth a turbo Automatic you have to consider the turbo characteristics and build your engine accordingly.....

Similar issue to the camshaft issue above, if the turbo doesn't boost till 2500 rpm then you really want a stall speed that is closer to this point than to the tickover point.

However, Nos is similar as you can't switch it on at low revs .... or shouldn't :-(

The best by far is more CC's.... 92mm crank 74.7mm bore giving you over 1625cc's

Or a turbo/NOS/SC with a higher stall speed convertor.

[Ethel]

My thoughts were to build the engine for low down torque and use fairly light boost to make the power where a short duration cam starts to gets wheezy. This is essentially what the Metro Turbo did, and with a not particularly suitable turbo. They ran 9.4:1 CR, and without an intercooler. You could even play around with wastegate actuation to tailor it around the auto gearshifts.

My other thought was nitrous to boost the bottom end to get a wilder cam up and running, apex over elbow to the norm, but similar to how it's used on some turbo applications. The downer would be squirting some of your nox straight through the exhaust overlap. It could be fairly economical as it would only be used in short blasts to to accelerate you by, say, 500rpm . Though you wouldn't want to rely on it and get stranded by an empty bottle.

[Skortchio]

A 1.6 A series you say, hmmm.

Realistically though, my aims remain the same to build (by whichever means) an engine to produce a wide flat torque curve north of 90ft/lb peaking somewhere above 95. This should give an really fun to drive mini with power delivery that lends itself to the auto box and avoids hunting for the power.

It essentially comes down to economy and application. If all routes can be made to work well enough with the auto box which one makes most sense, cost effective.
My budget isn't 'tight' but nobody wants to pay for caviar when peanut butter will do.

I've been quoted approx £2k for a 1330 build with head.
I can lay may hands on a fresh 1293 that would work for a turbo, leaving most of the budget left over for the turbo install itself.
I have no idea the relative costs involved in SC or things like 16v head conversions.

The gearbox upgrade will be done regardless so that's accounted for either way.

[Ethel]

You are pretty much describing a turbo installation. Maybe you should have a look at WilH's road going 998 for inspiration.

[Skortchio]

I'll give it a nose now, cheers Ethel. Getting a touch dizzy from trawling build threads endlessly looking for the important bits. Glad to be pointed in the right direction.

*Edit* Can't find a build thread. Where would I see this car?

Edited by Skortchio, 22 February 2013 - 02:53 PM.