7 port head and throttle body design...
Turbo Mini Forums

the injectors look a little on the steep side to me, arn't the meant to be around 25-30 degrees? they look more like 40 to me.

mind you, that may only really apply to NA setups.

I am going to make a new one next year because the fuel rail hitting the bonet. I dont want to have any holes in the bonet. So next year the injectors is going to be 25 - 30 degrees.

Edited by Dars on 16th Jun, 2006.

Just add my bit as Mr Theory Wanker, with regards to the port lengths, the lower the pressure, the lower the resonant frequency of the ports, due to the speed the wave travels, if you jack the boost up, the speed goes up and therefore the amount of cycles per second. I'm not sure how much this is or what order of size, if you were interested in the speed of sound at different densities (pressures), look in the CRC handbook of chemistry and physics. As the "suck order" of the 5 port goes OOXXOOXX it causes the first slug of charge to just get going and when fully going come charging into the next cylinder too fast, hence scatter cams. Whilst I love the fabrication and am very envious/curious, one of the snags must be that running a normal cam means that the 2 end cylinders will suck, followed by the nearest ones, etc, etc. That will set up a kind of resonance by itself, however it will be fucked up because of the boost. I'd expect that the greater the boost used, the higher the frequency and the less resonace effects you'd see. Anyway, it beats a 5 port. I'd say that the different runner lengths would just cause the power peak to be blurred a little.

British Vita had a Weslake head on one of their supercharged minis, the one with a fuck off great big rootes blower under it, they used equal length resonance tubes into a big cylindrical plenum. They were using a 649 cam though !!!! My mates ex-birds dad worked at Leyland ST and was into his blown engines and then fuel injection (back in the old days of big trumpets, etc). They had an 850 mini producing 100hp at the wheels with an aircraft cabin blower in the passenger footwell!!!

Looks like a good project and good luck to you. If you fancy discussing the resonance/pressure aspects of it, I've studied a fair old bit of chemical engineering.

Good Effort, Stu

Bugger off, I'm getting there.

I'm also thinking of a design for a turbo'd 7-port!

PM me and we'll compare notes.

Mark

I donated, but somehow didn't get the label! :(

Well, for my bit... we had a long thread on this one, because I have simlar plans of turbo'ing a 7-port engine... eventually!

I was going to use a plenum with a Toyota Glanza throttle body (based on the Glanza being 1300cc with a turbo, so basically same breathing requirements)

Marcel is using a Mazda 626 throttle body on his Elder 8-port.

An engineer friend of mine advised that for best results, the volume within the plenum had to be equal to the capacity of the engine... 1310cc, which accounts for a very large plenum, personally speaking.

Installation-wise, it could be a good idea to route the charge from the turbo (I'm using a T2 on a Mirage setup) through an intercooler in the traditional rad position, with an MPi radiator up front.

Alternatively, you can have a BIG bonnet vent with a bonnet-mounted intercooler.

Wanna make some cash by producing a second plenum for me?

I donated, but somehow didn't get the label! :(

The throttle body I am using is from a Ford escort 1.6. I found it one the scrap yard. I was only looking for somthing that didn't take up to much space.

I have tried to make the plenum ca 1300cc. But it always a question about space.

The intercooler is in the front position already.

There is some pictures on my web page. But the text is in norwegian.
www.my-minis.net

The port lenght is just a comprimise of the space again.

is your head an akm one or a minisport one?

AKM and MiniSport are the same heads Minisport have bought the AKM rights and toolings :)

www.shag.no

they're not quite the same.

As I understand it Minisport have done some work on the cores,

The inlet ports have been made a bit smaller, and Minisports trapezoidal exhaust ports have been cast into the head. Also after looking at my Minisport 7 port some one who has worked on an AKM casting reckons that the minisport casting is a bit thiner in places, ie near the exhaust seats.

The inlet ports are alleged by those that have worked on them to have been too large on the AKM casting, so Minisport have probably done the right thing there, i think they may have been beter leaving anything else alone though.

OK, I learn something every day :)

www.shag.no

My head would be a minisport head. Still waiting.

I've heard a few people say theres a wait....

is that for a finished head or a casting?

i bought a bare casting (which i recived about a year ago) and have Vmax doing the head work, I think it'll be better workmanship than minisport.

The head arrived 2 weeks ago. This is how it looks in the car. This is just a test. The car is running now but i haven't taken any pictures yet.