Megasquirt for muppets???

Martyn,how are you gettin on with tuning your ms?

 

This weekend has seen me get a whole lot closer to having a running car, as opposed to several large piles of bits I should hopefully be up and running in the new car this week, providing work isn't too busy.

 

Cool! ive been wading through vortex trying to learn as much as i can about itbs! Still unsure wot runner length to use and wether its to include the trumpets

 

Runner length does include the trumpets, it's basically the entire length from the inlet valve back to the bellmouth, providing there are no significant changes of diameter along the way. Tapered bores alter the lengths slightly due to the gas speeds changing along the length, but that's where it starts all going over my head

Have you seen this inlet pulse calculator? It's very basic but should give an idea of where to start. At the end of the day if you want to get it spot on you'll need to do some experimenting with different lengths at the RR.

 

Guys,

You got anymore info on intake ports!!!
Been looking for some today but can't find much of any use!
I have a set of CBR Carbs which I want to stick on a KR motor (if it is reviveable!). I have started to cut down and modify the lower half of the Inlet but now need to make up some pipes to match the inlet to the carbs but don't know how long they should be.

Someone once told me that the longer they are, the better the torque, the shorter they are, more high end power - this right?

 

Yes and no

For a certain length there will be an rpm band (or two) where the pulses in the inlet tract cause an increase in cylinder filling, but there will also be rpm bands where the opposite occurs, and you lose out some. Lengthening the inlet tract lowers the rpm at which these occur, shortening it raises them. The aim is to get a balance between having the beneficial pulses where you want them and the negative ones where you don't really care.

Also worth noting that a similar thing happens in reverse in the exhaust, but not many of us have the capability to play with lots of different exhaust runner lengths.

 

Can you buy the trumpets on there own??

 

Right, but there is no real way of knowing what these lengths are for any given engine/carb/ITB combination...

How about an adjustable manifold? Hmmmm......

Due to the fact that I need to make up my manifold myself for what I am doing, I dont really want to have to make up 3 or 4 different length versions to test which is best!

Oh well, trial and error then I suppose!

One question though. would it make a huge difference to the way the engine runs if the port length on cylinders 2 and 3 were slightly (only very slightly)longer than those on cylinders 1 and 4?
Due to the configuration of the carbs, I may have no choice in this. I am yet to see if the distances between them can be altered.

 

You don't need to bother with the hassle of different manifolds, easiest way to vary inlet lengths is with different length trumpets. Depending how your trumpets mount to the bodies/carbs, you could knock up some telescopic ones using some silicone hose, use them to find a nice lengths on the rollers, then get some more permanent ones made up/bought.

Unequal length runners will have a small effect on the engine, but as long as the difference isn't really pronounced it'll be OK. A lot of DCOE manifolds on the market are 'wonky'.

 

So when you fittin your itbs martyn?

 

er....


They've been sitting on my shelf for over a year now , it took me ages to get round to buying MS and getting stuck in, then as soon as I got that sorted the car failed it's MOT miserably on rust, so got scrapped

The major thing holding me back at the moment is the manifold. What I really wanted to do was use it as an excuse to learn to weld, and fab my own manifold, but this just isn't going to happen fast. I think at the mo i'm leaning towards making up the parts myself then getting it welded for me.

I need to get the car back on the road so I can drive it a bit and get some motivation. Since xmas I've basically had a driveable car for about a week, that was how long it took to get bored of the 8v engine and rip it out

 

Cheers Martyn!!!

 

Will this work??
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&rd=1&item=45 39985113&ssPageName=STRK:MEWA:IT
Edited by: flusted

 

That is a wideband sensor, you'd need a wideband controller to drive it, MS can't do it on it's own. The 7057 sensor is what I have with my Techedge WBO2, and is probably what Keith will get with his Zeitronix too.

 

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