M20 ITB's

[SkiFree]

it's still subjective and typically optimistic. There are so many more things at play that affect drivetrain loss.

also, what it makes at the crank is much less relevant than what it really makes at the wheels.

Certainly, I'm sure you'll agree its equally as subjective to make claims or generalizations about an engine/car that you (speaking generally) know no specs or details on other than the limited information I've listed.

[nando]

it's still subjective and typically optimistic. There are so many more things at play that affect drivetrain loss.

also, what it makes at the crank is much less relevant than what it really makes at the wheels.

[SkiFree]

A little more, not just based on internet spatter. It'll be the car-of-the-month for December, will have plenty more info.

It is calculating the lost of transmission when you go lower in speed.. And it gives you directly the power of the engine.. It's not a bosch device being to optimistic.. This one is a real one.. >From the technical engineers school..

And in action, skip ahead to the one minute mark.

http://www.youtube.com/watch?v=L28umKnmIMY

[nando]

yeah, they often have BHP converted #s. the problem is it's not easy to measure the real loss, and the curve isn't linear, so if you apply a straight 15 or 20% or whatever you feel like, you can get any number you want.

[digger]

Wow, is that 270hp ATW at 6500rpms? Looks like it from that chart. Even if that dyno is a bit generous, that is a very healthy M20.

Got any more info on the build? For example: what head was he using, what cam and what size ITB's...?

270bhp actually, being Europe they all convert to crank hp using varying correction factors. using the 16% stated it is 220-230whp which is about 10 more than what a cast manifold can do with a 'streetable' camshaft.

The headflow capability of the M20 head means that much more than 280bhp is a tough ask, i am talking a genuine number not a chassis dyno spitting out fantasy numbers and using bogus % losses.

you can tell bogus numbers by looking at the the BMEP at peak torque rpm and peak hp rpm and comparing to highly developed engines with similar configurations.

[clarkson]

Wow, is that 270hp ATW at 6500rpms? Looks like it from that chart. Even if that dyno is a bit generous, that is a very healthy M20.

Got any more info on the build? For example: what head was he using, what cam and what size ITB's...?

[SkiFree]

Even a well-choked 45 will be a bit much for street M20's. I've been playing around with hypothetical carb setup for the DCOE40's, will be happy to email the final settings. Digger's caveat holds true **if setup well**

A challenge with 40's is that most ITB manifolds sit at an angle parallel with the engine, starving the float bowel. Solutions are a bit Jerry-rigged. The other challenge is most ITB manifolds are cast/machined for 45's.



As a side note, customer in Switzerland running an IE 3.1 stroker with ITB's, he's coaxed quite a bit out of it.

[digger]

there is not much point running a carb on the street you'll only be better off at WOT peak hp if at all. Carb's (if setup well) often have better fuel atomisation compared to a relatively budget OEM style fuel injected setup and that is why they can make more peak hp, but you'll still need ignition control in which case at worst an AN would be pretty simple to setup. I ran AN with my stock manifold and TB setup and it worked fine and was liveable, albeit not as refined as a properly setup SD system. Using throttle bodies that are too big would also hinder tuning (not just midrange) as you would lose some resolution of the throttle

[whodwho]

Yup seen a few of them there, got to hear what lots of RPM sounds like on the dyno! I didn't get to see the final sheet but had seen it over 250 in the middle of the session.

[slippery]

Coming from the S2000 world, Church's dyno always reads extremely high. Great tuner though, he has tuned a lot of S2000s.

J

[LJ851]

I was involved with a Dyno tuning session this weekend with a M30 with ITBs, started out SD and ended up Alpha-N.

It did have one, it's just with a big cam and ITBs it has such a high kpa at idle there is not much to work with between idle and WOT. It dialed in nicely using Alpha-N and a Dynapack, turned out a beast 8^)

What were the final #s on the beast M30?

[whodwho]

It was being tuned at Church Automotive, that was the first I had met Shawn and it was a really busy day and didn't get much time to talk. I was just happy he worked with Megasquirt in the first place and not sure if he has worked with that mode. We were having 3 cars done and this was the last one and it was already dark and getting time to close. After seeing those Dynos in action I would never have anything tuned on an inertia one... great shop and highly recommended!

[nando]

did you try the ITB mode? Just curious, always wanted a reason to give that a shot.

in any case, there's many ways to skin a cat, no reason to go back to 1950s technology just because you have ITBs

[whodwho]

It did have one, it's just with a big cam and ITBs it has such a high kpa at idle there is not much to work with between idle and WOT. It dialed in nicely using Alpha-N and a Dynapack, turned out a beast 8^)

[nando]

you need a Vac log for it to work

but even doing Alpha-N should be pretty quick with a wideband and VEAL. and your tune won't change with the weather.. mechanical setups FTL. :p